The International Potato Center (CIP) is a not-for-profit, autonomousscientific institution established in 1971 by agreement with the Gov­ernment of Peru. C1P is one of 16 international research and trainingcenters supported by the Consultative Group on International Agri­cultural Research (CGIAR). The CGIAR is sponsored by the Food andAgriculture Organization (FAO) of the United Notions, the UnitedNotions Development Pragramme (UNDP), the United Notions Envi­ronment Programme (UNEP), and the World Bonk, and comprisesmare than 45 countries, international organizations, and private foun­dations. The information and conclusions reported in this publicationreflect the views of CI P.

Cover art based on a 9x12-inch mixed postel titledPartnership by Josephine Dell' Orco Prain

PROGRAM REPORT

INTERN

I

1995-

CENTER

Internatianal Potato CenterApartado 1558Lima 12, Perucip@cgnet.comhttp://www.cipotato.org

International Potato CenterProgram Report1995-1996

ISSN 0256-6311

September, 1997, 2 M

Copyright © International Potato Center 1997

The International Potato Center. 1997.Progrom Report 1995-1996. Lima, Peru. 323 p.

II

Overview of ClP Work in East and Southeast Asia and the PacificPeter Schmiediche

Alleviating Poverty Through Research Partnership

ConREPORTPROGRAM

Providing Better Access to CIP ResearchHubert Zandstra

RegionsOverview of CIP Work in Latin America and the Caribbean

Fernando Ezeta

Overview of ClP Work in the Middle East and North AfricaAziz Lagnaoui

Overview of ClP Work in Sub-Saharan AfricaPeter T. Ewell

Overview of CIP Work in South and West AsiaSarath lIangantileke

Program 1: Production SystemsThomas s. Walker

Prospects for Sustaining Potato and Sweetpotato CroppingSystems in Southwest Uganda

Jan W Low

Risk Analysis of Potato Production in the Altiplano:Quantifying Farmers' Beliefs 29

R. Valdivia Alatrista, R. Quiroz, R. Valdivia Fernandez, and V. Choquehuanea

Analyzing Potato Productivity in Farmers' Fields in Bolivia 34F. Terrazas, V. Suarez, G. Watson, G. Thiele, T. Walker, and A Devaux

Preferences of Urban Consumers for Andean Roots and Tubers in Ecuador 40P. Espinoza A and e.e. Crissman

Selection of New Sweetpotato Varieties for High Dry Matter Content in Indonesia 45II-Gin Mok, Lisna Ningsih, and Tjintokohadi

Collaborative Sweetpotato Breeding in Eastern, Central, and Southern Africa 49E.E. Carey, S. T. Giehuki, P.j.Ndolo, G. Turyamureeba,R. Kapinga, N.B. Lutaladio, and j.M. Teri

Tradeoffs in Agriculture, the Environment, and Farmer Health 58e.e. Crissman, j.M. Antle, and S.M. Capalbo

Program 2: Germplasm Management and Enhancement 67Ali Golmirzaie

Advances in Potato Cryopreservation by Vitrification 71AM. Golmirzaie and A Panta

Genetic Diversity Analysis in a Cultivated Andean Potato, S. phureja Juz. et Buk. 77M. Ghislain, D. Zhang, D. Fajardo, Z. Huaman, and R. Hijmans

DNA Markers for the Introgression of Late Blight Resistance in Potato 84M. Ghislain, B. Trognitz, e. Herrera, A Hurtado, and L. Portal

Identifying Duplicates in Sweetpotato Germplasm Using RAPD 90D.P. Zhang, M. Ghislain, Z. Huaman, F. Rodriguez, and j.e. Cervantes

RAPD Variation in Sweetpotato Cultivars from South Americaand Papua New Guinea 97

D.P. Zhang, M. Ghislain, Z. Huaman, A Golmirzaie, and R. Hijmans

Sweetpotato Breeding Strategy and Germplasm Testing in Southeast Asia 104II-Gin Mok, Tjintokohadi, Lisna Ningsih, and Tran Due Hoang

Advances in the Morphological Characterization of Oca, Ulluco,Mashua, and Arracacha Collections 11 0

e. Arbizu, R. BIas, M. Holle, F. Viva nco, and M. Ghislain

iv

Program 3: Disease Management 119Luis F. Salazar

Developing Horizontal Resistance to Late Blight in Potato 122}.A Landeo, M. Castelo, C. Forbes, }.L Zapatat and F.}. Flores

Resistance to Late Blight from Diverse Wild Sources 127B. Trognitz, M. Eslava, L. Portal, and P. Ramon

Evaluation of Late Blight Resistance in Populationsof Diploid Potato Hybrids for Genetic Mapping 132

B. Trognitzt M. Chislain, C. Forbes, P. Oyarzun,M. Eslava, R. Herrera, L. Portal, P. Ramon, C. Chacon

Host Specificity of Late Blight Pathogen on Potato and Tomato in Ecuador 138C.A. Forbes, P.}. Oyarzunt A Pozo, and M.E. Ordofiez

Use of Natural Resistance Genes for Transgenic Resistance to Potato Viruses 144M. Querci, G. Brigneti, }. Carda-Mast and D.C. Baulcombe

Encapsidation of PSTVd in PLRV Particles and Its Transmission by Aphids 150M. Quercit R.A Owens, and L.F. Salazar

Progress in Identifying Viruses Infecting Andean Root and Tuber Crops 156C. Lizarraga, M. Santa Cruzt and L.F. Salazar

Program 4: Integrated Pest Management 159Fausto Cisneros

Integrated Management for the Potato Tuber Moth in Pilot Unitsin the Andean Region and the Dominican Republic 162

M. Palacios and F. Cisneros

Integrated Management for Andean Potato Weevils in Pilot Units 169}. Alcazar and F. Cisneros

Developing IPM Components for Leafminer Fly in the Cafiete Valley of Peru 177N. Mujica and F. Cisneros

Large-Scale Implementation of IPM for Sweetpotato Weevil in Cuba:A Collaborative Effort 185

}. Alcazar" F. Cisneros, and A Morales

Integrated Pest Management for Sweetpotato in East Africa 191N. Smit and B. Odongo

Farmer Field Schools for Sweetpotato in Indonesia 198AR. Braun, E. Priatna, R. Asmunatit Wiyanto, Y. Widodo, and E. van de Fliert

v

Developing Weevil Resistance in Sweetpotato with Genetic Transformation 205D.P. Zhang, A. Colmirzaie, C. Cipriani, A. Panta, M. Chislain,N. Smith, I. Rety, and D. Michaud

Program 5: Propagation and Crop Management 211

Mahesh D. Upadhya

Simultaneous Selection for Yield and Stability in Hybrid True Potato Seed Families 214M. Upadhya and R. Cabello

Temperature and Moisture Affect Dormancy and Deterioration ofTrue Potato Seed During Storage 221

N. Pallais and R. Falcon

Frost-Tolerant Potato Varieties for the Andean Highlands 227E. Carrasco, A. Devaux, W Carda, R. Esprel/a

Sweetpotato Seed Units for the Dissemination of Planting Materials ofImproved Varieties 233

E.E. Carey, S. T. Cichuki, O. Hidalgo, and D.P. Zhang

Program 6: Postharvest Management, Marketing 239Cregory }. Scott

Making Sense of Agricultural Marketing in Asia, Africa, and Latin America 242C.}. Scott

Perceptions Versus Projections for Potatoes: New Estimates Point toa Changing Global Research Agenda 244

C.}. Scott and A. Coccia

Sustainability of Potato Consumption in Developing Countries:The Case of Bangladesh 249

C.}. Scott and H.E. Bouis

Improved Rustic Storage in South Asia 256S.C. Jlangantileke, V.S. Khatana, }.P'Singh, and D.Kumar

Recent Advances in ClP's Strategy for CollaborativePostharvest Research on Sweetpotato 264

C.}. Scott and C. Wheatley

Enhancing the Role of Small-Scale Sweetpotato Starch Enterprisesin Sichuan, China 270

C. Wheatley, Lin Liping, and Song Bofu

Feasibility, Acceptability, and Production Costs ofSweetpotato-Based Products in Uganda 276

V. Hagenimana and C. Owori

vi

The Potential of Root Crop Processing for Rural Development in VietnamG. Prain, C. Wheatley, and Nguyen Day Due

Perspectives on Sweetpotato: Dual-Purpose VarietiesC. Le6n-Velarde, }. Roea, j. Arteaga, L. Quispe, and A. Parraga

Crop Growth and Starch Productivity of Edible CannaM. Hermann, R. Uptmoor, I. Freire, and j.L. Montalvo

Cross-Program Training Courses 1995-1996

Scientific Publications 1995-1996

CIP Board Members 1995-1996

ClP Staff in 1995-1996

Acronyms and Abbreviations

282

291

295

303

305

313

314

320

vii

ever, that CIP research is in a period of tran­sition following our 1995 external reviewand because preparations for the initiationof the Center's 1998-2000 Medium-TermPlan were advanced by one year. Theseevents, combined with more comprehensiveimpact assessment and priority setting, haveled us to make some strategic adjustmentsin our research programs.

IX

The 1995-96 report also points to how OPwi II conduct its research under its next

For example, readers may note that thisreport contains more articles in the area ofbiotechnology, particularly in our DiseaseManagement and Germplasm Managementand Enhancement Programs. This representsa shift in OP research emphasis broughtabout by the recommendations of an exter­nal review and by a recognition among CIPscientists of the urgent need to avert a lateblight emergency in developing countries.In addition, readers can examine theprogress being made in virology, as CIP sci­entists are employing genetic engineeringin their work to incorporate naturally occur­ring virus resistance into advanced breed­ing lines.

Providing Better Accessto elP

Technically, our Program Report coversCIP research conducted in 1995-96 underthe able leadership of Dr. Peter Gregory,former Deputy Director General for Re­search. Readers should keep in mind, how-

OP's Program Report, published every twoyears, takes on a new look for 1995-96, andis more comprehensive than ever before.Previous reports covered scientific projectsso that they could be reviewed quickly, butrequired many readers to request follow-upinformation. In presenting this new report,our intention is to provide research partnerswith a fuller understanding of OP science,so that our work can be more easily repli­cated. The new format is intended to be moreuseful to a broader spectrum of scientists,including our traditional partners in nationalagricultural research systems, and research­ers in advanced laboratories and the privatesector. Together with our science reports, wehave included regional overviews of OPwork worldwide, which provide some of theneeds assessment and rationale for our re­search strategy. Presented here in publishedform, the entire report is also accessiblethrough CIP's home page (http://www.cipotato.org) on the World Wide Web.

Medium-Term Plan. As we gear up for astreamlined project portfolio that will be­gin in January 1998, the Center is adjustingits work programs, physical plant, and bud­get and management systems to accommo­date new priorities and initiatives. The Me­dium-Term Plan-which received highmarks from the CGIAR Technical AdvisoryCommittee-gives high priority to lateblight, the development of sweetpotato cul­tivars with higher dry matter content, andvi rus diseases.

In keeping with the Center's miSSion,these priorities are heavi Iy weighted to thoseregions of the developing world with largenumbers of poor people. Without exception,

x

the research covered in the report favorslow-income-especially women-farmers,labor-intensive technology that encouragesrural employment, and urban consumerswith limited funds for purchasing enoughnutrient-rich foods. CIP research emphasizeswork in and for those regions where agri­cu Itural productivity is threatened by envi­ronmental degradation and, conversely,where inappropriate farming practicesthreaten the natural resource base on whichagriculture depends. I believe that our newreporting format will assist our many re­search partners, and will help bring intogreater focus the need to meet these chal­lenges.

Hubert ZandstraDirector General

XI

throughout much of the Center's researchportfolio. In the case of late blight disease,our number-one priority, this includes a pro­gram of recurrent selection and multi­locational testing of host-plant resistance,complemented by diploid prebreeding,marker-assisted selection, and direct genetransfer.

The feasibility of this approach was il­lustrated over the past two years by Centervirologists working with partners in ad­vanced research laboratories. As a result oftheir collaboration, we now have availablea genetic map that provides the precise lo­cation of resistance genes for several keypotato viruses. Projections indicate that thecloned genes can be successfully intro­duced into advanced breeding lines andvarieties and made avai lable for testingwithin three years.

In the case of sweetpotato-now theworld's seventh-ranking food crop-OP re­search was directed toward a significant,but more limited, number of objectives. CIPsocial scientists, working closely with col­leagues at the International Food PolicyResearch Institute and in China, estimated

The 54 papers presented in this program re­port document a large segment of the ma­jor research initiatives conducted at CIP in1995-96. Center scientists from each of oursix program areas-together with represen­tatives from the consortia and advancedlaboratories with whom we conduct our re­search-share authorship for these reports.

Introduction: AlleviatingPaver Throu h

Research

Potato and Sweetpotato

The papers present various aspects of theCenter's research agenda, particularly thoseelements of our program focused on envi­ronmentally friendly production systems andthe many yield-reducing factors that affectroot and tuber crops. ClP's research also em­phasizes developing technologies that pro­vide farmers with greater access to morediversified markets and, at the same time,protect endangered upper watershed ecolo­gies.

In pursuit of these goals, ClP began to shifta higher percentage of its resources intoupstream research in 1995. The blending ofconventional and molecular approaches inCIP's breeding program, for example, illus­trates the important changes taking place

that sweetpotato production in developingcountries wi II increase at an average an­nual rate of 1 percent for the period 1990­2020. This calculation is consistent withlong-term trends and emerging evidencefrom several countries, which indicate abottoming-out in the decline in area plantedor, as in the case of sub-Saharan Africa, asharp increase in production.

After more than five years of diagnosticwork in genetics, production and food sys­tems, and socioeconomics, CIP researchersformulated a renewed sweetpotato researchagenda. The new strategy is based on thehypothesis that production and use in sub­sistence farming systems are constrained byvarieties that are poorly adapted and low indry matter. In response, CIP scientists be­gan to use the high-dry-matter accessionsfound in Center-held collections for varietalimprovement targeted at poor countries insub-Saharan Africa and Southeast Asia, andthe poorer provinces of China. This workshould produce high-quality sweetpotatocultivars suitable for direct consumption andfor use as animal feed, starch, and flour prod­ucts.

In addition, ClP scientists began to screencultivars suitable for production in areassubject to drought. A major objective of thiswork is to make sure that farmers, particu­larly in the harsher environments of sub-Sa­haran Africa, have enough seed cuttings forplanting once the rainy season begins. TheCenter's sweetpotato breeding program inAfrica also reflects the crop's potential tooffset the impact of cassava mosaic virusand black Sigatoka, diseases that nowthreaten food production in much of east­ern and central Africa's most populated ar­eas.

Genetic Conservation

The work reported here on genetic diversityanalysis is the first use of molecular mark­ers at ClP to fingerprint an entire cultivatedpotato collection (Solanum phureja Juz. etBuk.l. CIP scientists also developed a cost­effective protocol for genotyping large

xii

germplasm collections using RAPD tech­niques, or randomly amplified polymorphicDNA. Integrating these and other molecu­lar methods of germplasm management­together with more conventional conserva­tion methods-could lower germplasmmaintenance costs 30-40 percent, and al­low greater investment in evaluation andutilization.

Along similar lines, cryopreservation re­search begun in 1995 should provide long­term solutions to the problem of maintain­ing vast numbers of traditional root and tu­ber varieties in conventional gene banks.ClP continued its work through national sys­tems to safeguard nine exotic Andean cropspecies for farmers working in marginal ar­eas, especially in the highlands. By the year2000, Center scientists believe it will bepossible to reduce investments in conserva­tion and shift emphasis to research on utili­zation and marketi ng.

CIP has also begun efforts to support com­munity groups that wish to conserve theirgermplasm in situ, and works to improvelocal varieties through participatory plantbreeding programs. We expect these initia­tives to reduce pressure on conventionalgene banks, encourage natural evolution,and contribute to genetic diversity.

Natural Resources Management

Though less advanced than our work onpotato and sweetpotato, conservation oflesser-known Andean genetic resources isconducted through CONDESAN, the Con­sortium for the Sustainable Development ofthe Andean Ecoregion. In 1995-96,CONDESAN involved work by more than100 public-sector organizations, universi­ties, and NGOs from seven Andean coun­tries. One particularly important study com­pleted in 1995 presents startling informa­tion on the health risks associated with in­secticide use and provides policymakerswith new methods for assessi ng the tradeoffsbetween agricultural productivity, environ­ment, and health.

CONDESAN, working in the establishedtraditions of other ClP-coordinated researchnetworks and consortia, is also a key ele­ment of the CGIAR's Global Mountain Pro­gram. The Program's goal is to compare landuse patterns and provide technological op­tions that can be used across the world'sgreat mountain systems. As with all CIP re­search, the overriding objective is to seektechnological solutions that help alleviatepoverty through increases in productivityand the enhancement of natural resources.

We ask readers to recognize that ClP sci­entists work from the premise that the poorshould benefit proportionally more fromCenter research and training activities thando others. Implicitly, gender and povertyconcerns strongly overlap with this goal.Although the reports presented here may notalways explicitly express these concerns,the research behind them is geared exclu­sively toward improving the lives of the ru­ral and urban poor in ways that are effec­tive, equitable, and ultimately sustainable.

xiii

Overview of CIP Work inlatin America and the Caribbean

Fernando Ezeta1

Regi

CIP Progrom Report 1995-96 1

gains are better varieties, access to qualityseed, and improved agronomic practices,including dose and timing of fertilizer ap­plication. In spite of the obvious progress inpotato agriculture observed over the pastfew years, average yields per unit area re­main well below productivity levels in in­dustrialized nations. Several constraintscould be removed to increase overall po­tato output, basically via increased produc­tivity. Over the next few years, ClP wi IIconcentrate efforts in developing technol­ogy and assisting Latin American and Car­ibbean NARS in improving potato pest anddisease management, improving seed qual­ity, and introducing processing attributes tonew varieties.

REPORTPROGRAM

Potato production in Latin America has grownat an average annual rate of 2% over the past30 years. This expansion of the total outputresulted mainly from improved productivitysince the area in potato remained stable atnearly 1 million hectares for the region. Butthe aggregate regional figures do not reflectimportant differences among subregions andcountries. Productivity gains have been greaterin the Southern Cone countries and CentralAmerica than in the Andean region. Expan­sion of area was observed in Colombia, Cuba,Ecuador, and Mexico only, whereas in mostother countries of the region potato area de­creased or remained the same.

Among the technological interventionsthat have led to remarkable productivity

1 Regional Representative, Lima, Peru.

Disease Management

Late blight (LB) is the main constraint topotato production in most of Latin Americaand the Caribbean (LAC). OP's breedingprogram for resistance to LB with testing inPeru, Mexico, and Colombia (Rfonegro),which led to population A, has producedseveral LB-resistant varieties for the region.In Costa Rica, three clones of population A,introduced in 1991, were released as vari­eties in 1996. About 50% of the potato areain Costa Rica is now planted to these newvarieties that are rapidly replacing cultivarsGranola and Atzimba, which are extremelysusceptible to LB. In Panama, two varietiesselected from population A were releasedby IDIAp1 • One of them, named IDIAFRIT,has excellent attributes for the french friesindustry. In the Andean countries, ClP's LB­resistant clones have been released in Bo­livia, Colombia, Ecuador, Peru, and Venezu­ela. In the Southern Cone, clones of popu­lation A have been used as progenitors inbreeding programs. Direct adaptation ofclonal selections from Andean environ­ments to the growing conditions of the South­ern Cone has been limited by the demandthere for earliness and good tuber appear­ance.

The spread of a new, more aggressive popu­lation of the LB causal agent, Phytophthorainfestans, together with growing environmen­tal concerns have triggered regional efforts tosupport the Global Initiative on Late Blight,sponsored by CIP. The principles of searchingfor durable resistance without R genes andintegrated disease management (lDM) arewidely accepted all over the region. Argen­tina is actively screening R-gene-free popu­lations adapted to long daylength. OtherSouthern Cone countries are equally interestedin early screening of R-gene-free populationsin the search for well-adapted, early LB-resis­tant materials. It is expected that PICTIPAPAand the potato research networks of the re­gion will support research for durable resis­tance in their subregions.

1 Acronyms cited in this section can be found written out inthe section Acronyms, p. 320.

2 LAC Region

The introduction of virus resistance is alsoof high priority in the region. Several breed­ing programs are making intensive use ofCIP's PVX- and PVY-resistant populations tointroduce resistance into their populationsthrough conventional breeding. In Uruguay,variety IPORA, generated by INIA, incorpo­rates PVY resistance from ClP's PVY-resistantpopulation. The in~roduction of virus resis­tance is likely to have a remarkable impacton seed renovation rates, especially amonglow-income potato producers.

Bacterial wilt continues to be an impor­tant constraint to potato production through­out the region. Movement of large quantitiesof seed from infected areas seems to be themain dissemination mechanism. Over thepast three years, ClP has organized workshopsto alert research institutions and governmentplant health services to the problem. Theseworkshops provided the opportunity to rec­ommend actions to reduce, or possibly elimi­nate, the problem through IDM, quarantine,and the production of healthy seed.

Pest Management

Progress on integrated pest management(IPM) in LAC has been outstanding. In theAndes, pilot projects for control ofthe potatotuber moth (PTM) and the Andean potatoweevil have proven the viability of the inte­grated approach to keep these pests beloweconomic threshold levels. Technology com­ponents developed at ClP have been testedin farmers' fields to evaluate not only the tech­nology itself but also training and communi­cation materials. The program had a strongtraining component that reached techniciansas well as potato farmers at the communitylevel. In Peru, incorporating NGOs into theprogram increased the dissemination of IPMpractices through extension services.

The successful application of IPM tech­nology to the sweetpotato weevi I (Cylasformicarius) in Cuba and the Dominican Re­public must be highlighted. The sweetpotatoweevil had gotten out of control in Cuba un­til the IPM program began. Now, the programis expanding rapidly, thanks to a well-orga-

nized extension service and well-defined in­dividual control components. Among thecomponents are effective sex pheromonesthat attract males into traps where they areeliminated by physical methods or by local­ized pesticide applications.

Significant progress has been made in con­trolling the leafminer fly (LMF) through IPM.In the central coast of Peru, where potatoesare grown in the winter, farmers have beenable to reduce multiple insecticide applica­tions to only two by adopting IPM practices.The use of yellow traps to catch adult fliesdramatically reduces LMF populations. At thesame time, the reduction in pesticide appli­cation favors biological control, which hasproven to be extremely efficient.

Planting Materials

Although seed production technology is quitewell disseminated in the region, the progressof seed production systems is below expec­tations. Public efforts to create a certified seedsystem have been unsuccessful in most casesbecause of the strong informal seed systemsthat supply seed to commercial growers. Nev­ertheless, in recent years the seed businesshas attracted the interest of the private sec­tor. Private seed growers are adopting mod­ern seed technology for rapidly multiplyinghealthy seed stocks. The progress made inpathogen detection of viruses and viroids isalso a major contribution to improved seedquality standards. In summary, thanks to pri­vate efforts, local capacity for seed produc­tion in LAC has expanded in recent years.

True potato seed (TPS) as an alternativesource of healthy planting material has beensuccessfully used in Nicaragua and Peru.Other countries in Central America are ex­ploring its potential. In Nicaragua, potato pro­duction depends on imported seed, which isexpensive and physiologically immature. Theexperience with TPS has been rapidly assimi­lated into the production system of Nicara­gua with good market acceptance. In the Pe­ruvian highlands, the experience withChacasina, a hybrid of a Peruvian variety andClP clone 104.12 LS, has been so successful

that farmers now have 200 kg of TPS as asource of seed for the coming years.Chacasina is a high-yielding TPS progenywith good acceptance among the consum­ers of this remote highland region, wheregood-quality clonal seed was extremely dif­ficult to get before the project started.

Changing Markets

All over Latin America there is a growing in­terest in improving the processing quality ofpotatoes for chips and fries. The rapid expan­sion of the fast-food business in the regionhas created a demand for precooked frozenfries that, with few exceptions, is being metwith Canadian imports. Most countries, how­ever, would like to substitute locally producedpotatoes for imports. Dry matter content andfrying quality of advanced clones have beenconsidered as important selection attributesin most breeding programs of the region. Withthe present rate of development of the potatoprocessing industry in LAC, varietal accep­tance is likely to be closely linked to process­ing quality in addition to agronomic traits andpest resistance.

Globalization and free-market economicsare introducing important changes in potatoproduction systems and markets of LAC. Theprogressive removal of trading barriers be­tween countries within subregional commonmarkets is increasing trade and competitionamong them. This more competitive environ­ment poses a threat to small farming units andfavors large-scale, high-input productionunits.

On a more global scale, LAC potato agri­culture may face severe competition in thefuture from producers in industrialized coun­tries. Production costs in most LAC countriesare usually higher than in North America, anissue of major concern as LAC economiesopen up and reduce trading tariffs.

Collaboration

Collaborative potato research networks inLAC (PRECODEPA, PRAClPA, and PROClPA)have confirmed their validity as mechanisms

(IP Program Report 1995-96 3

for the horizontal transfer of technologyamong members. Although at present onlyPRECODEPA counts on external funding, thelinks established between researchers inPROCIPA and PRACIPA continue to facili­tate the exchange of research results.

Electronic communication is essential intoday's research and development efforts.

4 LAC Region

CIP is therefore fostering the consolidationof an electronic information network,INFOPAPA, that aims to link potato re­searchers of all research networks withinLAC. We expect INFOPAPA to acceleratethe exchange of knowledge and informa­tion among members efficiently and inex­pensively.

Overview of CIP Work in the Middle Eastand North Africa

Aziz Lagnaoui1

The close proximity to Europe, the relativewealth of the Middle East and North Africa(MENA) region, and the strong commercialappeal of potatoes make this commodity moreof a cash and export crop. Up to 75% of Dutchseed exports, out of Europe, are destined tocountries in the MENA region. These samecountries are in turn potato exporters duringthe winter months, mainly to the United King­dom, France, and Germany. The special tradearrangements between the European Commu­nity and several MENA countries will certainlycontinue to influence this trend. ClP's com­parative advantage is the potential to increaseyields by concentrating on crop and pest man­agement research.

Our Regional Action Plan and priority-set­ting for 1995-96 focused on reducing environ­mental hazards of potato production systemsby developing and disseminating biologicalcontrol methods for major pests. CIP has aclear comparative advantage in these activi­ties and research results can be effectivelyused immediately. ClP showed impact inactivities and places where a staff scientistwas posted to work closely with counterpartsin the national program. In response to ourchallenge to "focus on fewer things in fewerplaces," areas that held uncertain promisesof success were avoided and promising re­search was continued to avoid a dilution ofeffort. The research team concentrated on in­tegrated pest management ((PM), true potatoseed (TPS), and healthy sweetpotato plantingmaterial.

With the strong belief that IPM is at thefoundation of sustainable agricultural devel­opment, we continued to implement CIP's IPM

1 Regional Representative, Tunis, Tunisia.

strategy through participatory research andtraining, promoting public awareness of thebenefits of IPM, and involving policymakers.

Integrated Pest Management ofPotato Tuber Moth

Our IPM strategy was to implement a processwhereby potato growers in the MENA regioncould begin to substantially reduce their de­pendence on toxic pesticides for control ofthe potato tuber moth (PTM). Over the pastfew years, ClP and its partners in the Tunisiannational program have developed effectivepractices for controlling PTM, the insect pestmost responsible for significant losses in theregion. Implementing the PTM managementstrategy was basically reduced to an educa­tional process.

Recognizing the considerable opportunityto alter present PTM control practices in bothTunisia and Egypt, we invested our efforts in

• demonstrating advanced IPM technologieson-farm;

• promoting national policies that supportthe use of IPM; and

• training national scientists and extensionspecialists to implement IPM on a largescale.

By capital izing on the soundness of the IPMstrategy in Tunisia, we achieved a gradualshift in priorities as the Tunisian national pro­gram was encouraged to begin the large-scaleimplementation of IPM. We worked to deter­mine the best way to extend IPM practiceson a larger scale and to accelerate adoption.

In Tunisia, adoption of improved controlpractices has all but eliminated unnecessary

(IP Progrom Report 1995-96 5

insecticide sprays for PTM control in fields.The adoption of Bacillus thuringiensis (Bt) andgranulosis virus (GV)-based insecticides issteadily increasing.

Complementary research focused on en­hancing GV activity by formulating it withvarious compounds to put an additional stresson the insect. That should reduce the timerequired for the virus to kill PTM and lowerthe pathogen dose needed.

Improving traditional storage structures wasalso deemed necessary, so we called on OPstorage specialists to design an improved tra­ditional storage facility. The Tunisian Minis­try of Agriculture is funding the constructionof pilot storage units in the major potato-pro­ducing areas.

The involvement of policymakers, includ­ing the President of Tunisia, generated unprec­edented excitement for IPM in the researchand extension community. That is likely toaccelerate the adoption of IPM. As antici­pated, the success of the Tunisian project isproviding the foundation for the adoption ofIPM in the other potato-producing countriesin the MENA region.

In Egypt, a ban on the most widely usedpesticide for PTM control in storage precipi­tated interest in the use of B. thuringiensis andgranulosis virus. As a result, mass productionof GV and Bt is increasing and quality is im­proving. In addition, 400,000 capsules of PTMsex pheromone for use in pheromone trapshave been produced. Off-farm implementa­tion is a trend in newly reclaimed areas. Grow­ers contract with agencies or companies tocontrol PTM using Bt and GY. A similar sys­tem was used in the past in the cotton IPMprogram, which is mainly designed to protectfarmers from crop losses.

Integrated Disease Management

Causal agents of soft rot and dry rotA survey of potato diseases in fields and in

summer rustic stores was conducted in Tuni­sia to identify the main pathogens responsiblefor storage losses.

6 MENA Region

No incidence of soft rot or blackleg wasfound, although Erwinia carotovora and E.chrysanthemi were isolated from importedseed lots. In traditional stores, watery woundrot (WWR), also called potato leak, causedby Pythium aphanidermatum and P. u/timum,was prevalent. Tubers exhibited a discolora­tion similar to the pink rot symptom. AlthoughFusarium roseum var. sambucinum was iso­lated from imported seeds, it was dry rotcaused by F. so/ani that showed a high inci­dence in stores. Losses in summer rustic storeswere correlated to the seed health status ofthe previous spring crop.

In the field, wilt was caused by soil patho­gens such as Verticillium dah/iae and F. so/anivar. eumartii. P. aphanidermatum was alsoisolated from wilted plants; losses at harvestwere mainly due to WWR. Wilt incidencewas not correlated to seed health status but tothe cropping system (successive planting ofsolanaceous plants), thus showing the impor­tance of soil infestation in the transmission ofdisease.

Watery wound rot managementPythium aphanidermatum and P. ultimum

were found to be seed-transmitted as well aspersistent in Tunisian soils. Because of the highincidence of these pathogens on-farm and inlarge-scale stores of the Tunisian seed program,we investigated various components of inte­grated management of WWR.

Comparison of varietal susceptibility. Wedeveloped a method to assess susceptibilityto WWR and tested several European variet­ies from the national list. Among these, onlyvarieties Korrigane, Superstar, Safrane, andYesmina were found to be moderately suscep­tible.

Biological and chemical control. Seedtreatments with the antagonistic soilsaprophyte Trichoderma harzianum or withfungicide solutions of Ridomil (metalaxyl10%, mancozeb 48%), mancozeb, maneb,or hymexazol efficiently controlled WWR de­velopment in the laboratory.

Disinfecting soil by solarization. Popu­lations of Fusarium solani and of Pythium sp.were significantly reduced by soil mulching.The benefit of the method on potato growthand weed control was demonstrated in ex­periment station and on-farm trials.

Baiting technique. A simple baiting tech­nique using oat seeds to detect and quantifysoil populations of P. aphanidermatum wasestablished. A detection threshold of 1-10oospores/g of soil will allow us to identifynoninfested soils for local seed multiplication.

Research begun on the control of WWRwill help to formulate effective integratedcontrol recommendations for local seed mul­tipl ication.

All surveys and research efforts have beenperformed in collaboration with the staff ofthe Tunisian seed program and the Ministry ofAgriculture. Extension specialists have beentrained to improve their ability to diagnosestorage disease. The identification of the mainpotato pathogens in Tunisia also permitted usto establish tolerance thresholds for certifica­tion schemes and importation agreementsmore appropriate to local conditions.

Furthermore, these findings will greatlyassist scientists in formulating integrated dis­ease management (I DM) approaches for po­tato soft and dry rots.

Sweetpotato in Egypt

Newly released varieties Kafr EI-Zayat I andKafr EI-Zayat II, varieties Jewel andBeauregard, and the selected advanced cloneA 193 were produced in large quantities in thenewly constructed screenhouses at ClP's KafrEI-Zayat station. So far, 300,000 healthy plant­lets were produced at the CIP station and dis­tributed to farmers by the national programfor on-farm evaluation; over 2 million plant­lets were produced by the private sector. Asimilar operation is being set up in Syria(spinoff effect), where local planting mate­rial is degenerating. We will continue to em­phasize the quality of planting material andpromoting wider use of the crop.

True Potato Seed

The performance of TPS hybrids and recentadvances in TPS use led to greater transfer ofthis technology to Egyptian farmers. A num­ber of entrepreneurial farmers started to pro­duce seedling tubers from TPS at 50% the costof locally produced seed tubers. Our liaisonoffice in Egypt is catalyzing interactions withthe private sector and government organiza­tions. Already a spinoff effect is taking placein neighboring countries as Syria has begunexperimenting with promising progenies.

The Future

Over the years, CIP has ensured greater im­pact on-farm by strengthening the researchcapabilities of our national partners, by en­couraging farmer participation, and by en­hancing communication between the researchand implementation institutions. In the yearsahead, we will focus on the transfer and imple­mentation of acquired knowledge on IPM andIDM to ensure greater impact on-farm andcontribute to the sustainability of productionsystems in key countries in the region (Egypt,Tunisia, Morocco). We will also seek to pro­mote linkages with institutions in countries ofthe Middle East Uordan, Yemen, Syria).

Persistent challenges in the region are theever-increasing threats posed by potato tubermoths, whiteflies, and leafminer flies as a re­sult of intensified potato cropping in severalMENA countries. Furthermore, special empha­sis should be placed on the evaluation of thepotential contribution of biotechnology topotato and sweetpotato production in the re­gion. In accordance with IPM principles andbiosafety guidelines, transgenic material willbe carefully evaluated for its effectiveness andeffects on nontarget species before deploy­ment.

The most important challenge is to en­sure long-term continuity of CIP's work inthe region and to respond to new requestswhile maintaining a minimal physical pres­ence. One way of meeting that challengeis to develop special country projects asneeds are identified and defined.

CIP Program Report 1995-96 7

Overview of CIP Work inSub-Saharan Africa

Peter T. Ewell!

Sub-Saharan Africa is a large and diverseregion. Of its 47 countries, 36 report potatoand/or sweetpotato production to the FAO.In the aggregate, food production has failedto keep pace with population growth, andper capita production has declined. Chronicdeficits are made up with imports and foodaid. According to the World Bank, 21 of the30 poorest countries in the world-with GNPper capita per year below $430-are in sub­Saharan Africa. Natural environments, cul­tures, and economic conditions vary mark­edly among countries. Vast regions aresparsely populated deserts and forests. Semi­arid lands, subject to periodic droughts, ac­count for large areas. Both potato andsweetpotato are grown primarily in denselypopulated, intensively cultivated highlandand mid-elevation zones. They play impor­tant, contrasting roles in the food systemsof the region.

Potato and Sweetpotato in Africa

Potato is a short-season, high-value crop,grown as a cash crop and for household con­sumption. According to the FAOSTAT data­base on the Internet, about 400,000 hectaresare harvested in sub-Saharan Africa. Potatoproduction reported in Africa as a whole hasnearly tripled over the past 35 years, from 1.3million tons in the early 1960s to 3.7 milliontons in 1996. This growth has been consis­tently and sign ificantly higher than that of thepopulation. This reflects the crop's growingimportance as a food in rapidly growing ur­ban areas.

Broadly speaking, there are three majorpotato systems:

1 Regional Representative, Nairobi, Kenya.

8 SSA Region

1. In the densely populated, high-poten­tial highland areas (1,800-2,750 m) of east­ern and central Africa, potatoes are grownby small farmers (0.5-2 hal both for themarket and for home consumption. Yieldsvary between 5 and 20 t/ha, with a mean of8-1 0 t/ha. Rates for chem ical ferti Iizer andfungicide use vary widely among countriesand production areas, but are generally lowbecause farmers cannot afford chemicalsand supplies are unreliable. Seed is obtainedprimarily from informal, local sources andaverage seed quality is low. Late blight andbacterial wilt, as well as viruses, causechronic, significant yield losses.

2. In southern Africa, particularly in SouthAfrica, potatoes are grown on a relativelylarge scale in the modern farming sector. Irri­gation is becoming more important, good­quality seed is available, inputs are used in­tensively, and average yields are high-from15 to over 25 t/ha in South Africa.

3. In Cameroon and Nigeria, potatoes arean important smallholder crop in higher ar­eas. Elsewhere in West Africa, the crop isgrown on a very small scale as a high-valuevegetable, usually under irrigation.

Sweetpotato is an important food securitycrop grown in almost every country on thecontinent. Approximately 1.5 million hectaresare planted, primarily in rural areas for homeconsumption. Although the overall growthrate in reported production has fallen behindtotal population growth, sweetpotato has sig­nificant potential for increased use.

Sweetpotato is a low-input crop, easilypropagated from vine cuttings, that is grownunder a wide variety of conditions, from in­tensive irrigation to commercial rainfed fields

and to millions of small plots in and aroundfields of other crops, along roadsides, inbackyard gardens, and in urban plots. Thecrop is most important in eastern and cen­tral Africa, including Cameroon, in denselypopulated, intensively cultivated mid-eleva­tion (1,200-1,800 m) areas, slightly lowerthan where potatoes are grown in most ofthe same countries. Elsewhere in eastern andsouthern Africa, sweetpotato is an importantsecondary food in diets featuring maize andother cereals. The crop is important in cer­tain regions and periods of the year, such asin the "hungry months" when stores are ex­hausted and the next grain crop awaits har­vest. Diets in the lowlands of West Africaare dominated by cassava, yams, and otherstaples, and sweetpotato plays a minor role.

Research in Partnership withNational Institutions

CIP set up its regional program in sub-SaharanAfrica in the mid-1970s. The goal has beento work with national potato and sweetpotatoresearch programs and other partner institu­tions on key issues facing increased produc­tion and use. In 1996, nine CIP internationaland regional scientists were working in theregion: five in Kenya, three in Uganda, andone dividing time between Cameroon andNigeria. These scientists were directly in­volved in core-funded, collaborative researchwith national scientists in Kenya, Uganda,Cameroon, Ethiopia, Tanzania, and Nigeria.

Strong links were maintained with otherpotato and sweetpotato programs throughthe PRAPACEl network for central and east­ern Africa and the SARRNET network for theSADC countries of southern Africa. Thesenetworks provided the context for CIP's par­ticipation in seed relief and program reha­bilitation projects in war-torn Rwanda andAngola. More limited contacts are maintainedwith countries that are not network members,for the distribution of information andgermplasm.

1 Acronyms cited in this section can be found written out inthe section Acronyms, p. 320.

Collaborative research is concentrated insix major project areas:

1. Potato late blight. Late blight is thesingle most important potato disease in theregion, particularly in the tropical highlandenvironment of central and eastern Africa.Temperatures in the major production zones(1,800-2,750 m) are relatively even. Therainfall pattern is bimodal, and inoculum isalmost continuously present. Farmers do nothave the income to spray fungicides regularly,and the disease causes serious yield reduc­tions in most years. The disease is less signifi­cant in the drier areas of southern Africa.

Over the past 20 years, blight resistancehas been the principal trait of new varietiesadopted by farmers in countries throughoutthe region. Several advanced clones are nearrelease and are expected to do well, althoughR genes are present and their resistance islikely to break down eventually. Sets of geno­types from population B, with better horizon­tal resistance, are in the early stages of selec­tion in Kenya, Uganda, and Ethiopia. As theGlobal Initiative on Late Blight develops, CIPand its national partners will increase theirinvestments in research, particularly to pro­mote integrated disease management on­farm.

2. Farmer-based potato seed systems inKenya, Uganda, Ethiopia, and Cameroon.Farmers need healthy seed, which is avail­able on their farms at planting time, in theright physiological state, at a price they canafford. Centralized systems for seed multi­plication and certification modeled on thosein Europe and North America have provendifficult to implement and maintain in pub­lic-sector institutions in Africa. An alterna­tive is to provide selected farmer-multipli­ers with clean starter seed stock, and sup­port them to become special ized in themultiplication of seed for sale to other farm­ers in their area. This also provides a mecha­nism to get new varieties to farmers.

The facilities that ClP developed overmany years in collaboration with the PlantQuarantine Station in Kenya for the intro-

CIP Program Report] 995·96 9

duction and testing of germplasm for re­gional distribution have been converted intoa seed unit. The best available varieties aremultiplied in vitro as "starter stocks" for seedprograms in target countries. Linkages havebeen developed with NGOs with contactsin pilot potato-producing communities tofacilitate selection of suitable farmers, train­ing in seed techniques, and support for con­structing diffused-light stores.

'!!

3. Integrated disease management forpotato. 10M is the only practical approachto bacterial wilt, as the disease organismpersists in the soil, is carried by infectedseed tubers, and cannot be controlled withchemicals. In Uganda, CIP is collaboratingwith NARO, the national research institute,in the African Highlands Initiative, anecoregional program linked with the GlobalMountain Initiative. Its purpose is to take amulti-institutional, multicommodity approachto improving resource management in the in­tensively cultivated high-potential areas of thehighlands.

One project is the integrated managementof diseases associated with increasing landuse intensity and decreasing soil fertility. Bac­terial wilt is one offour diseases being inves­tigated. A full-time regional scientist attachedto CIP to work on the project has shown thata package of improved rotation, clean seed,tolerant varieties, and improved on-farm sani­tation reduces losses, even on very smallfarms. Strategies for improved managementprovide an entry point, to encourage farmersto improve their land use management, withimmediate payoff in increased potato yieldsand longer-term payoffs in stable soil fertility.

4. Sweetpotato improvement. From thelate 1980s, ClP's regional program has im­ported advanced sweetpotato cultivars fromthroughout the world for distribution andevaluation. At the same time, true seeds pro­duced from crosses made by Uganda's na­tional program and from elsewhere are be­ing tested at a few locations.

Farmers grow diverse combinations of lo­cally adapted varieties, which tend to be late-

1OSSA Region

maturing and low-yielding. Planting mate­rial is exchanged informally among rela­tives and neighbors, and only a few intro­duced varieties have become establishedin sub-Saharan Africa over the past 25-30years. African farmers are interested in newvarieties if they meet certain criteria: highyield, earl iness, and persistence of plantsin fields so that planting material is avail­able for the next season. Drought-tolerantvarieties would permit the expansion ofsweetpotato cu Itivation in drier areas anddrier periods in the year. Good taste is veryimportant both for home consumption andfor sale in the market. Consumers like rootswith high dry matter (usually at least 27­28%) and moderately sweet taste. Resis­tance to or tolerance of viruses, weevils,and other pests and diseases could help ex­pand the range of the crop and increaseyields.

New varieties for new or expanded usesalso have significant potential. Most Africanconsumers prefer roots with white or cream­colored flesh. Orange-fleshed varieties canprovide significant quantities of vitamin A,which is critically short in the diets of manyrural people, particularly children. Prelimi­nary evidence shows that mothers will grow,prepare, and serve new varieties, if they un­derstand the implications for the health oftheir families. Sweetpotato vines are high inprotein and are an excellent forage for ani­mals, particu larly for weani ng calves and kids.They are currently fed as a by-product, butdairy farmers will plant new varieties withhigh forage yields specifically for this purpose.Varieties for processing will be planted if se­cure markets become available.

5. Integrated sweetpotato crop manage­ment. The most Widespread and damagi ngpest in eastern and southern Africa, particu­larly in dry areas and in dry years, issweetpotato weevil (Cylas spp.), a focus ofCIP's collaborative research. A number ofother insects, viruses, and fungal diseasesare important in certain areas. Collabora­tive research in Uganda and Tanzania, withassistance from the Natural Resources Insti­tute, has isolated sex pheromones of all three

species found in Africa, and is testing theiruse for monitoring and possibly mass-trap­ping. Several cultural practices, such as main­taining an adequate separation betweensweetpotato fields, careful hilling, and re­moval of all residues from plots after harvest,have been shown to reduce damage.

Pilot projects are being established inUganda to work with farmers to see how thesecomponents can be adjusted and combinedto provide effective protection against wee­vil damage. Most successful IPM programshave been adopted by farmers because theyhelp to reduce pesticide applications, therebyreducing costs. As pesticides are not used onsweetpotato except by a small minority offarmers, the challenge is to develop packagesthat increase yields sufficiently to justify theincreased labor, cash costs, and managementattention. Broadening the approach to includeadditional key constraints in an integratedcrop management package is a key to suc­cess.

6. Expanded postharvest use of sweetpo­tatoo In Africa, sweetpotato roots are con­sumed almost exclusively in fresh form;most are usually just boiled. In other partsof the world, particularly in Asia, use ofsweetpotato as a raw material in the pro­duction of processed foods, feed, and indus­trial products has increased significantlyover the past 40 years. The adaptation ofknown products and processes to African

conditions could open up new markets forfarmers. The use of a locally grown, low­input crop in processed products could alsoreduce the countries' need for food importsto meet the needs of rapidly growing cities.

Collaborative research in Kenya andUganda has demonstrated that a ready mar­ket exists for homemade products such asflat bread (chapa tis) and doughnuts(mandazis), which substitute cooked andmashed sweetpotato for a certain proportionof the usual wheat flour. Farmers in someareas cut roots into chips and dry them inthe sun to preserve them. These processesare being improved so that the dried chipscan be ground into a high-quality flour, whichcan be easily stored and transported, andused in mixtures with wheat and other floursin baked goods.

Other Activities

CIP's regional office provides a link be­tween scientists working in national institu­tions and research throughout the world.Courses, short-term attachments, and studytours provide training in research and ana­lytical techniques. CIP scientists act as ad­visors for many student thesis projects. Sup­port for networks and a number of bilateral,regional, and multi-institutional projectshelp ensure that researc~ responds to theneeds of potato and sweetpotato farmers inAfrica.

(IP Progrom Report 1995-96 11

Overview of CIP Work inSouth and West Asia

Sarath Ilangantileke1

The largest potato producer in the South andWest Asia (SWA) region is India, followedby Bangladesh, Nepal, Pakistan, Sri Lanka,and Bhutan. Sweetpotato production ismainly in India, Bangladesh, and Sri Lanka;production in other countries is localizedand of little significance.

Potato

The SWA region produces about 21 milliontons of potatoes on 1.3 million hectares. Inthe past decade, total potato production inIndia has increased rapidly, with compara­tively slower increases in Bangladesh,Bhutan, Nepal, Sri Lanka, and Pakistan. In­creases in total production in countries otherthan India and Bhutan are attributed moreto a gradual expansion in area than to sig­nificant yield increases. Among the six re­gional countries, India currently has thehighest national yield average (16 t/ha),whereas Nepal has the lowest (8.3 t/ha).

Potato is used mainly for the fresh market.However, local and multinational snack andfast-food industries are developing rapidly inthe region, and India is striving to providepotato for the domestic processing industry.Estimates indicate that about 9,000 tons ofthe crop are now processed annually in theunorganized sector alone in India. Tradewithin the region in seed and ware potato isexpected to increase in the future with newtrade agreements between the SWA coun­tries. Demand for selected processing andhigh-yielding varieties will therefore increasesteadily.

Problems of cultivation in the region, al­though similar, are location and ecoregion

1 Regional Representative, New Delhi, India.

12 SWA Region

specific. A major problem is the availabil­ity of high-quality local seed for ware andprocessing. Countries outside India dependon either imported seed or low-quality lo­cal seed. But late blight and bacterial wiltsignificantly affect yields in all SWA coun­tries. Postharvest problems of storage andmarketing already exist and may becomemore pronounced with increased productionand future trade in the region. The intensi­ties of problems differ significantly.

As a regular major activity, potatogermplasm was distributed from ClP-Limaand the regional office to NARS, networks,NGOs, and private-sector organizations in theSWA region. This catered to the increaseddemand for germplasm for specific breedingrequirements such as processing and diseaseresistance.

Development of healthy seed material isan important activity. Increased interestamong farmers in TPS technology has resultedin a remarkable increase in crop productionarea in different agroecological regions ofIndia. In addition to domestic use, large quan­tities of TPS produced in India have been ex­ported to Vietnam, Egypt, Indonesia, and thePhilippines outside the SWA region, and toBangladesh, Nepal, and Sri Lanka within theregion.

Regular farmer training programs and ex­tension activities by NARS in collaborationwith CIP have helped increase TPS produc­tion and use in Bangladesh. TPS demonstra­tion projects and farmer trai ning on loca­tion-specific agronomic practices in Nepalhave resulted in increased use of TPS in themid-hills and lowlands (Terai region). Al­though production of true seed in Nepal is

limited, use of TPS from India has shown anupward trend. The Asian Development BankTPS project in Sri Lanka has provided assis­tance in evaluation and farmer demonstra­tion trials. Research on TPS continued fordeveloping earliness and disease resistance.

Training in the region has been dominatedby TPS-related training, a major reason forthe rapid increase in TPS use. An interre­gional workshop on TPS production and useheld in India had participants from China,Vietnam, Sri Lanka, Indonesia, the Philip­pines, Nepal, Bangladesh, and India, as wellas scientists from CIP-SWA and the ESEAPregion. The private sector, progressive farm­ers, and NGOs were also represented. CPRIand ClP-SWA jointly gave field training onTPS production and use to scientists fromSri Lanka and Bangladesh. Individual andgroup training activities on TPS in the re­gion included training on hybrid TPS pro­duction and use for research workers, farm­ers, agricultural officers, field assistants, andNGOs in India, Bangladesh, and Nepal.

The search for new areas for potato pro­duction in India has resulted in the use of ri­verbeds to cultivate potato in Orissa, withassistance from ClP. We have already ob­served an increase in production area. Thistechnology targeted specifically to resource­poor farmers and to the use of underused landresources is gaining popularity and has pro­vided significant increases in potato yields.

Seed and ware potato storage performsan important function in the production andmarketing of the crop in the region. In In­dia, large quantities of potato are stored incold stores immediately after harvest. Farm­ers unable to avail themselves of cold-storefacilities store the produce on-farm untilprices begin to increase two to three monthsafter harvest. Storage in heaps and in tradi­tional structures results in losses. Researchon an alternate method of storage using rus­tic evaporative cool stores was continuedin three large potato-producing districts. Anational workshop on problems of potatostorage in India was held for scientists, farm­ers, policymakers, and cold-store owners as

a way to identify future strategies for stor­age research.

In the future, ClP needs to address sev­eral potato activities in the SWA region:varietal improvement for end use, diseaseresistance, and productivity; availability ofhigh-quality seed and efficient seed sys­tems; postharvest and marketing; and de­velopment of human resources.

Sweetpotato

The SWA region produces about 1.6 milliontons of sweetpotato on 0.2 million hectares.India accounts for 68% of the total produc­tion, followed by 27% in Bangladesh andabout 5% in Sri Lanka. Sweetpotato is animportant crop for Sri Lanka and occupies1.1 % of the total cropped area, followed by0.5% in Bangladesh and less than 0.1 % inIndia.

Although production area in Pakistan isinsignificant, yields of more than 10 t/ha arereported, followed by 9.5 t/ha in Bangladesh,8.3 t/ha in India, and 6.5 t/ha in Sri Lanka. InIndia, yields have improved since the mid­1980s, whereas yields in other countries havedeclined gradually after the respective peakyield years.

Use is limited to consumption as a veg­etable in all SWAcountries, with an insignifi­cant quantity of processed snack food, lim­ited to India, followed by Bangladesh. Indus­trial use is nonexistent.

A major problem is the availability ofideal varieties for different agroecologiesand different cropping systems in the region,where crop duration influences yield poten­tials. High incidences of sweetpotato wee­vil and other pests and diseases limitachievement of maximum yields, while alack of postharvest utilization methodologyand marketing chains limits enthusiasm toelevate the crop beyond its present statusas a "poor man's" crop.

The production and use of sweetpotatoin the diets of people of South and West

(IP Program Report 1995-96 13

Asia are expanding. The striving to popular­ize the use of sweetpotato in diets has re­sulted in the exchange of germplasm fromneighboring countries. Sweetpotatogermplasm distribution was done in vitro andas stem cuttings, as requested by NARS ofBangladesh, Nepal, and Sri Lanka; networksof different organizations; and NGOs andprivate-sector organizations in the region.Varieties having high carotene content weresupplied to a USAID nutrition project inNepal. C1P-SWA supported travel and atten­dance at international seminars and confer­ences.

Sweetpotato breeding in collaborationwith NARS of India has resulted in a transferof advanced clones for evaluation toBangladesh and Sri Lanka, and to researchorganizations in the sweetpotato-growing ar­eas of India. A sweetpotato production andweevil control course in India for farmers andagricultural officers of Goa was held to en­courage increased production. Such activi­ties will be increased to help popularize thecrop.

Like for potato, varietal improvement forend use, increased availablity of high-qualityplanting material, and postharvest/marketingand development of human resources areimportant activities for CIP-sWA in develop­ing sweetpotato production in the region.

Collaborating Institutions

Research was done in collaboration withNARs. In India, with the Indian Council for

14 SWA Region

Agricultural Research and its institutes-theCentral Potato Research Institute and theCentral Tuber Crops Research Institute (forsweetpotato), the Department of Horticulture,state universities, NGOs, farmers, and private­sector organizations. In Bangladesh, collabo­ration was with the Bangladesh AgriculturalResearch Institute's Tuber Crops ResearchCenter. A notable feature in Bangladesh wasNGO interactions to help diffuse TPs.

Regular training programs and travelgrants were provided to NARs scientists. CIPprovided MSc and PhD programs for re­searchers in Bangladesh and India on TPstechnology and on sweetpotato varietal se­lection and evaluation, respectively. Out­side funding sources were solicited throughthe GBF (Society for Biotechnological Re­search) for NARS scientists for a three-monthtraining in biotechnology in Germany.

Expected Accomplishments

Potato and sweetpotato are important cropsin the diet of people in the SWA region.Activities conducted by CIP are expectedto lead to sustainable seed and planting ma­terial systems in countries with needs. CIPwill also work toward marketing andpostharvest strategies that will result in seedself-sufficiency and a production environ­ment with economic benefits for potato andsweetpotato farmers.

Overview of CIP Work in East andSoutheast Asia and the Pacific

Peter Schmiediche1

Potatoes account for rough Iy half of theworld's annual output of all roots and tubersand, since the early 1960s, the increase inarea planted in developing countries has beenhigher than for any other major food crop.Annual world production currently totals 274million tons on 18 million hectares, and Chinaand India alone produce 22% of this total.

The potato sector worldwide is in transi­tion. Europe and the former Soviet Unionaccount for the bulk of production, but thesituation is changing rapidly. In the early1990s, about 30% of the global potato out­put was produced in developing countries,up from 11 % in the early 1960s. If this trendcontinues, in less than a generation, most ofthe world's potatoes will be harvested in Asia,Africa, or Latin America. As a result, potatois becoming an increasingly importantsource of food, rural employment, and in­come for the growing populations in theseregions.

Over the past three decades, Asia has ex­perienced the world's highest annual growthrate in potato production. With its short crop­ping cycle, potato fits well into Asian foodproduction calendars, and is particularly com­patible with fast-growing hybrid cereals. Theexpansion of cold storage, the rapid emer­gence of processing facilities for the fast­food industry, and the indirect influence ofimproved rice and wheat irrigation systemshave also contributed to the expansion ofpotato production in Asia. Low prices rela­tive to cereals combined with the economicimpact of improved storage systems havestimulated greater demand. This trend iscontinuing strongly in all Southeast Asian

1 Regional Representative, Bogar, Indonesia.

potato-growing areas, particularly in thosethat feed the rapidly expanding urban con­centrations and megametropolises of thisregion. Demand is strongest for processedpotatoes that supply the fast-food industryin these urban centers where processed po­tato products fetch top prices, thus convert­ing this tuber into a highly profitable cashcrop. This increasing demand puts strongpressure on national and international breed­ing institutions to produce high-quality pro­cessing varieties that are well adapted tothe wide array of agroecological conditionsin Southeast Asia.

Even if more and more varieties with therequired processing and culinary qualitiesbecome available, the lack of adequate seedsystems is the single most important impedi­ment to the development of the crop. A prof­itable crop starts with high-quality seed, butunfavorable agroecological conditions in­terfere with the production of such seed inmost Southeast Asian potato-growing areas.

One solution to the seed problem is theuse of botanical or true seed instead of con­ventional propagation from tubers. True po­tato seed (TPS) has promise in severalagroecological niches of Southeast Asia. Onesuch area is the Red River Delta (RRD) aroundHanoi, Vietnam, where several thousandhectares of potatoes will be grown from TPSduring 1997-98 to avoid the disease prob­lems associated with traditional tuberplantings. The hybrid seed grown in Viet­nam was developed in ClP-sponsoredprojects in India, where seed production isnow in the hands of the private sector. TheTPS project in Vietnam is sponsored by theAsian Development Bank, and this project

(IP Progrom Report 1995-96 15

is in the process of revolutionizing potatoculture in the RRD, where more than 90%of Vietnam's potatoes are grown. It is alsointroducing hybrid TPS production in theRRD and in the highland area around Dalatin south Vietnam. In addition, Vietnam isusing numerous introductions of CIP potatogermplasm to great effect. Several variet­ies or potential varieties have been selectedfor those areas where the TPS technology isnot yet in use.

According to Chinese sources, ClP potatogermplasm has boosted China's successfulbreeding program since the early 1980s whenit had stalled because of the lack of geneticvariability. Potato variety CIP-24 now occu­pies more than 250,000 hectares in China.Results of CIP's basic phytopathology re­search have been successfully used in China'sseed potato program and in the integratedcontrol of late blight and bacterial wilt. Apartfrom transferring technology, CIP has assistedwith numerous training events for groups andindividuals inside and outside China.

Because potato is affected by more pestsand diseases than any other food crop, it hasbecome a heavy user of pesticides, with theassociated negative effect on the environ­ment. To reduce pesticide use, programs ofintegrated pest management (IPM) have beendeveloped for this region. CIP's ESEAP re­searchers collaborate with governmental andnongovernmental organizations to promoteintegrated pest and disease managementbased on four principles originally developedby the FAO Intercountry IPM Program forRice:

• grow a healthy crop,• conserve the natural enemies of pests,• monitor fields frequently and, through

training and hands-on experience,• farmers become expert practitioners of

integrated pest management.

In sweetpotato culture, the most impor­tant issue to be resolved in this region isthat of sweetpotato use. The problem of useis closely followed by the need to controlthe sweetpotato weevil, the most important

16 ESEAP Region

sweetpotato pest in Southeast Asia. Efforts

to control the weevil with classical IPMmethods have evolved into a comprehen­sive package of integrated crop manage­ment oeM) since national programs will not,as a rule, implement an isolated IPM solu­tion that does not address other related prob­lems of raising a successful sweetpotatocrop. As already indicated for potato, inAsia, the first principle of ICM is "grow ahealthy crop," implying the central positionof IPM within an approach of integrated cropmanagement. Successful ICM depends oncoupling the classical activities of deploy­ing host-plant resistance, using biologicalcontrol, reducing pesticide use, enhancingand protecting natural enemies, and deploy­ing sex pheromones with equally classicalagronomic measures. Moreover, ICM canonly be successful if individual farmers andthe farming community understand and par­ticipate in these measures. This has beenachieved through a series of highly success­ful Farmer Field Schools in Indonesia. Theconcept of ICM and Farmer Field Schoolsis now spreading to other countries in thisregion, particularly Vietnam, where it willbe appl ied to both potato and sweetpotatoculture.

A special project funded by Swiss Devel­opment Cooperation (SOC) concentrated onthe collection, classification, and use ofsweetpotato biodiversity in Indonesia, com­bined with a pioneer effort to document theassociated indigenous knowledge of thisgermplasm to facilitate its rapid use. Thisproject was designed to identify sweetpotatogermplasm that would meet specific needs,initially of Indonesian sweetpotato cultivatorsand later of growers in other areas of Asia.Exploration of in situ conservation techniquesfor sweetpotato is under way in Indonesiaand the Philippines.

China's principal sweetpotato-breedinginstitutions have worked closely with CIP'sregional sweetpotato breeder in the use of awide array of germplasm to develop cultivarswith high dry matter content. A highly visibleand successful program, using virus-freesweetpotato planting material in Shandung

Province, has been acknowledged to havebenefited from basic virus research and asso­ciated training activities conducted by ClP.

Sweetpotato processing, as it relates to theuse of starch for noodle production, is anotherarea in which great advances have been madein China, particularly in Sichuan Province­the largest area of sweetpotato production inChina. Research on sweetpotato pig-feedingsystems in that province is an area of enor­mous potential, with spillover possibilities forother provinces of China.

A major CIP-UPWARD' initiative on theuse of sweetpotato and canna in north andcentral Vietnam completed a detailed assess­ment of research needs, and sweetpotato isnow being introduced as an alternative sourceof starch for noodles and as an improvedsource of pig feed. Vietnam's strength in po­tato and sweetpotato research is in no smallpart the result of highly active ongoing CIP­sponsored and ClP-mediated training effortsduring the past 15 years.

ClP's impact in the Philippines has beenachieved through four institutional structuresthat developed and implemented a series ofprojects to address the needs of potato andsweetpotato culture in that country: (1) theUPWARD network, which, although regionalin scope, has been particularly active in itshost country; (2) the regional ASPRAD2 net­work, which implemented a significant num­ber of highly successful potato andsweetpotato projects through its active coor­dinating office in Los Banos; (3) the SANREM3watershed-based, natural resources manage­ment activities in Mindanao; and (4) potatoseed research and development, imple­mented through CIP's seed unit in Baguioand through ADB-financed TPS research inLuzon and Mindanao.

1 UPWARD (Users' Perspectives With Agricultural Researchand Development).2 This network used to be known as SAPPRAD (SoutheastAsian Program for Potato Research and Development) beforeit was renamed ASPRAD (Asian Sweetpotato and PotatoResearch and Development). Its Australian fundingterminated on December 31, 1996.3 SANREM (Sustainable Agricultural and Natural ResourceManagement).

Production-level impacts are promisingthrough the diffusion of ClP-derived potatogermplasm via formal and informal seedchannels in the conventional potato produc­tion areas, and through the use of TPS inMindanao.

Significanttakeoff is already evident in theuse of Farmer Field School approaches to theintegrated management of bacterial wilt. Ur­ban home gardens research in northern Phil­ippines is now showing payoffs with large­scale expansion in the use of improvedsweetpotato germplasm and other technolo­gies. Institutional impact has been achievedthrough the adoption of participatory ap­proaches to research by many institutions,involving farmers, farming communities, andother end users of potato and sweetpotato inresearch. For example, participatory varietyevaluation procedures developed by ASPRADhave been adopted in the Philippines and inother countries. Interagency research partner­ships developed by UPWARD are now prac­ticed by local institutions. Filipino agriculturalresearch institutions have highly trained in­dividuals and, through UPWARD andASPRAD, Filipino scientists have been ableto make a significant research impact in othercountries of this region through short-termconsu Itancies.

In Indonesia, research has concentratedon the introduction and testing of new po­tato germplasm, the use of TPS as an alter­native seed system, the integrated manage­ment of bacterial wilt, the integrated cropmanagement of sweetpotato through devel­opment of the Farmer Field School model,and the preservation of sweetpotatobiodiversity and indigenous knowledge as­sociated with sweetpotato biodiversity. ClPhas also contributed in significant waysthrough PhD training to the pool of agricul­tural research expertise in potato.

In summary, ClP has responded flexiblyand with the prudent use of scarce humanand financial resources to the needs of thisregion. Results and impact are apparent andthe foundations for further advances havebeen laid.

elP Program Report 1995·96 17

1 Program Leader, CIP, Lima, Peru.

PreviouS Page Blar

Thomas S. WalkerI

(IP PlOgram Report 1995-96 19

Characterization of Constraints

Characterization of production constraintsand opportunities is an area of declining im­portance. Several studies were completed in1995-96. In potato, lessons from five years ofparticipatory farmer selection of late-blight­resistant varieties were drawn and reportedin Bolivia. Diagnostic research explainingyield variation in farmers' fields in Bolivia ispresented later in this report. The compara­tive advantage in potato production acrossthe three main producing regions of Ecuadorwas assessed. Surveys of national agriculturalresearch systems (NARS) provided data fordocumenting present levels of investmentin potato crop improvement programs andfor prescribing resource allocation, giventhe importance of potatoes in national

ProREPORTPROGRAM

Production Systems

Since the last Program Report (for 1993-94),the Production Systems Program has contin­ued to emphasize work in three areas: (1)characterization of constraints and produc­tion opportunities in potato and sweetpotato,(2) adaptation and integration of potato andsweetpotato production technologies, and (3)

assessment of the impact and sustainabilityof potato and sweetpotato production tech­nologies.

Research and training highlights in thesethree areas are presented for 1995-96, andimplications of the Medium-Term Plan 7998­2000 for program activities are described. Inparticular, the management of natural re­sources is an emerging area of emphasis asCIP responds to environmental concerns inshaping its portfol io of activities.

production and assumptions on expected ef­fects.

In sweetpotato, the last of five country char­acterization studies in eastern and centralAfrica was completed for Tanzania. Prospectsfor intensifying and sustaining sweetpotatoproduction in response to increasing popula­tion pressure were also examined at threebenchmark sites in southwestern Uganda.

The agroecological characterization ofsweetpotato production systems was re­viewed in Asia. Institutionalizing a participa­tory approach in root crop research was thefocal point for both research contracts andtraining workshops for NARS partners inChina, Indonesia, Nepal, the Philippines, andVietnam.

In the medium term, characterization re­search will be merged with impact assessmentinto one project for potato and another forsweetpotato. Priorities for potato include up­dating the perceptions, first elicited in 1987,of NARS scientists on constraints and oppor­tunities; characterizing constraints and oppor­tunities for production in the central Asiancountries; and evaluating regional competi­tiveness in production. For sweetpotato, theglobal synthesis of information from invest­ments in characterization research in the earlyand mid-1990s is still the main priority.

Technology Adaptation

Advanced varietal testing and release figuredprominently in technology adaptation. Inpotato, several virus-resistant, heat-tolerantvarieties with good processing traits were re­leased for early and late planting in coastalPeru. These varieties will extend the lengthof the growing season and hence reduce sea­sonal price fluctuations.

Steady progress was made in the advancedtesting of sweetpotato varieties. In Uganda,the most important producer of sweetpotatoin sub-Saharan Africa, five varieties were re­leased by the national program. Although CIPwas not intimately involved in the breeding

20 Program 1

or selection of these varieties, their releaseestablished an institutional precedent for thedistribution of promising CIP-related mate­rial.

In 1998, research on varietal adaptationwill take place in self-contained projects inother OP programs. Work on adapting virus­resistant potato varieties will become part ofthe project on potato viruses. Simi larly, adap­tive trials on advanced sweetpotato materialwill be subsumed into the project onsweetpotato dry matter and adaptation.

Impact Assessment

Turning to the area of impact assessment, amonograph documenting the impact of nineOP-related technologies was published in1996. Two priority-setting exercises, whichused information from the impact case stud­ies, were also carried out and reported. Theselaid a firm foundation for OP's Medium-TermPlan 1998-2000.

Among OP-related technologies, true po­tato seed (TPS) received the most scrutiny.Results from several years of on-farm trialsformed the building blocks for an ex ante as­sessment in Egypt, India, and Indonesia.

In the future, selective case studies of expost impact will still be conducted. However,we will place more emphasis on evaluatingthe effects of improved technology on pov­erty and the environment. Some of this workwill be carried out in the framework of therecent CGIAR initiative on impact assessment.Examining the effects of cyclical price insta­bility on potato production and consumptionis a policy-related area targeted for intensivestudy.

Natural Resources Management

Organizationally, Production Systems is thelocus for much of CIP's increasing investmentin research and training in natural resourcesmanagement. Selective investments in sys­tems modeling, soil fertility management, andnatural resources economics supplied CIP

with a critical mass to tackle issues related toland use in the Andes and to intensive po­tato-cropping systems. Research addresses thecommon theme of interactions between landproductivity, technological change, pol icyintervention, and environmental improve­ment or degradation. This work is highlycomplementary to CIP's potato research aspotato cropping systems are usually pivotalto the sustainability of land use systems intropical mountain environments. Modelingapproaches, featuring widespread participa­tion from developing-country NARS and men­tor institutes, are used to overcome problemsof site specificity, which erode the transfer­ability of research results.

ClP's contribution to research on thesustainability of land use in the Andes is con­ducted within the CONDESAN network andis embodied in two research and training ac­tivities.

The first activity, DME-Norte, marries bio­physical and economic models to examinetechnology, policy, and environmental sce­narios. It draws on and extends models de­veloped in recently completed research ongroundwater contam ination as a conse­quence of the heavy use of pesticides in po­tato production by small farmers. Potatoesrotated with pastures is the land use of inter­est for modeling.

The second project, DME-Sur, combinessatellite imagery with biophysical models toassess frost, drought, and salinity risk in crop

and livestock production. We are also evalu­ating technological and policy options tomitigate the severity of these abiotic stressesin one of the largest and poorest regions ofthe Andes.

Production Systems also houses naturalresources management research carried outin the Global Mountain Initiative (GM!) con­vened by CIP, ICIMOD, and ICRAF. This ini­tiative stimulates research and synthesisacross the three most important tropical andsubtropical mountainous regions of the world.Priority research areas include agroecologicalcharacterization, integrated nutrient manage­ment, agricultural intensification in responseto population pressure, the fate of investmentsin soil conservation, and dairy policy.

The sustainabi lity of intensive potato-crop­ping systems is the third area of natural re­sources management for program activity.This project begins in 1997 and focuses onsustainability of rapidly expanding potato pro­duction in the Indo-Gangetic Plain of SouthAsia. Initially, attention will be directed attheintensive rice-potato-rice system in regionsthat have witnessed spectacular growth inpotato production since 1985. This projectwill be executed under the umbrella of theCGIAR's Rice-Wheat Program.

Looking ahead, Production Systems is rap­idly evolving into a natural resources man­agement program. The name of the programwill likely be changed to recognize this shiftin emphasis.

OP Program Report 1995-96 21

Prospects for Sustaining Potato andSweetpotato Cropping Systems inSouthwest Uganda

JanW.Low

Many of the most productive agricultural sys­tems in sub-Saharan Africa are located in thedensely populated highlands of Eastern andCentral Africa. Kabale District in southwestUganda is representative of the highlands inthis part of the world. Potato figures promi­nently as a cash crop, and sweetpotato is animportant food crop.

Kabale District provides an opportunity toexamine the dynamic roles of potato andsweetpotato in an area of intensifying agri­cultural production in response to increasingpopulation pressure and market demand.Moreover, ClP participated with the NationalAgricultural Research Organization ofUganda in re-establishing potato research andseed production activities at the Kalengyereresearch station in Kabale District from 1989to 1994.

This study has two main objectives: (1) toobtain baseline data on current productionpractices in representative sites so varietalchange and other technology-related issuescan be monitored over time, and (2) to assessthe prospects for the intensification andsustainability of potato and sweetpotato pro­duction.

To address these objectives, we undertookfield research in three phases. In February1995, we visited potential sites, defined as adistinct valley with surrounding hillsides, heldgroup discussions with farmers, conducted in­formal market surveys, and made final siteselections.

1 Formerly at CI P Sub-Saharan Africa regional office,Nairobi, Kenya.

22 Progrum 1

Subsequent field work combining struc­tured household surveys with agronomic ob­servations on potato and sweetpotato plotswas done in September 1995 and February1996. In total, we interviewed 134 potato pro­ducers and 89 sweetpotato growers. All thesweetpotato growers were women; the ma­jority of the potato producers were men. Fig­ure 1 shows the geo-referenced survey data.

Of 17 potential field sites, 3 were selectedto provide a range of agroecological condi­tions in the production of potatoes in a val­ley or neighboring hillside where sweetpotatois also an important crop. Kalengyere is ahigh-altitude area (2,100-2,500 m) of inten­sively cultivated, steeply sloped hills. Bukinda(at 1,700-1,900 m) is lower than Kalengyereand much warmer. Therefore, conditions areless favorable for potato production. How­ever, both potatoes and sweetpotatoes arewidely grown on the hillsides and in the val­ley bottom. Kicumbi (at 1,800-2,100 m) issomewhat higher, and its most notable fea­ture is the huge, flat Katuna valley. Parts ofthe valley floor are dominated by largerfenced landholdings for pasturing dairy cattle.In other parts of the valley, wall-to-wall po­tato is seen during the dry season. Extensivesweetpotato ridges with deep drainage canalsdominate the hillside landscape.

Changing Roles of Potato and Sweetpotatoas Income and Food Sources

Growers were asked to assess whether theimportance of potato and sweetpotato hadbeen increasing or decreasing, or had re­mained the same, during the past five years,both as a food for home consumption and as

Kicumbi(1,800-2,100 m)

•

(IP Program Report 1995-96 23

Sweetpotato, on the other hand, has neverbeen an important cash crop in Kabale Dis­trict. Therefore, the 32 households noting anincreasing significance of sweetpotato as acash crop is of interest. This increase was at­tributed primarily to increasing demand forthe crop, particularly near urban centers suchas Kabale, and for feeding students in board­ing schools.

Bukinda(1,700-1,900 m)

•~o=.

Many more respondents stated that theimportance of sweetpotato as a cash crop wasdeclining because of decreasing market de­mand as well as declining yields. These farm­ers complain that because everyone growssweetpotato and there is no market for thecrop outside of the local area, it is demandedlocally only when other foodstuffs are in shortsupply.

Declining yield has also contributed to areduction in the role of sweetpotato for homeconsumption. That is a disturbing trend, giventhe traditional year-round rei iance onsweetpotato as a food security crop in Kabale.

Kalengyere(2,100-2,500 m)

•·0.=..Research ••

Station

a source of income (Table 1). Over half thegrowers reported that potato was increasingin importance as a source of cash and as afood for home consumption.

They cited two major reasons for this in­crease: increasing demand in the marketplaceand the high productivity of the crop, in partbecause of new varieties. Potatoes as a foodare also becoming more popular. Greaterhome consumption is in part a reflection oftheir greater avai labi Iity at the household levelas aby-product of planting more of the cropfor cash sale.

Figure 1. Research sites in Kabale benchmark survey.

In spite of the better market for potatoes,some farmers reported a decline in the im­portance of potato as a cash source duringthe past five years. The overwhelming rea­son for this tendency was declining yields.Farmers cited poor soi I fertility or disease ascontributing factors. Yield decline also figuredprominently in the minority perception thatpotatoes were diminishing in importance asa food crop.

for reosons

8848

4378'1

14

184

24

58

7618

32

Sweetpotato

Cosh Food

12141

1473371

lent yields (29.5 t/ha). It would be highly de­sirable to sustain these yields, albeit withlower production costs. At the other end ofthe spectrum, potato yields for Kicumbiswampland farmers are already low (7.7 t/hal.The system is fragile and yield increases areurgently needed. Sustaining mean yield lev­els of 19.6 t/ha at the lower altitudes (1,800­2,100 m) of Bukinda over time would meanthat potato would remain an important cashcrop within this area.

In interpreting these yield data, it is impor­tant to note that the mean potato plot size onthese farms is small, ranging from a low of560 m2 in Bukinda to a high of 812 m2 inKicumbi. Thus, even the high yield of 29.5t/ha in Kalengyere translates into 2.0 t (ap-

9 5 356 10 6

7

'1 5 102 2

1 244 113

trend;

2

24 Program I

Results from on-farm yield assessment of po­tato production indicate that farmers inKalengyere are, in general, obtaining excel-

Sustainability of Potato Production

In higher-elevation areas, such asKalengyere, sweetpotato is also losing groundto potato as a food for home consumption. Ingroup discussions, Kalengyere mothers oftenremarked that children preferred potatoes tosweetpotatoes. Older household members re­tained their preference for sweetpotato as astaple food. In contrast, the eroding role ofsweetpotato in home consumption in Bukindaand Kicumbi, where preference forsweetpotato over potato remains high, is al­most exclusively attributed to declining yields.

Table 1. The perceived changing impartance af potato and sweetpotato as cash and food crops in Kobale District,Uganda, 1995-96.

proximately 19 bags) of potatoes from an av­erage plot size of 699 m2

•

Several encouraging signs point to sus­tained production of potato in Kabale Dis­trict. They include (1) high demand for pota­toes in Kampala, the capital city, (2) improvedroad infrastructure, (3) increasing entrepre­neurship, (4) increasing input use, and (5) theexistence of late-blight-tolerant varieties.

The greatest threat to sustained potato pro­duction in Kabale District is the increasingincidence of two major diseases: late blightcaused by Phytophthora infestans and bacte­rial wi It caused by Pseudomonassolanacearum. Farmers lack knowledge ofrecommended control practices so their abil­ity to employ them is severely constrained.Although farmers can recognize the symp­toms of both diseases and know the associa­tion between high humidity and late blight,knowledge of the causes of bacterial wilt isextremely limited (Table 2).

Moreover, their awareness of nonchemicalapproaches to dealing with late blight isscanty (with the exception of delayed plant­ing to avoid heavy rains). Knowledge of howto prevent the spread of bacterial wilt and dealwith an infected field is marginal to nonexist­ent. The introduction of some agronomicpractices, such as roguing volunteer potatoplants, may encounter considerable resis­tance, in that many farmers perceive thesere-emergent plants as an important source offood.

Although the use of animal manures andcrop residues on potato fields is increasing,steep terrain and limited availability makemanure application a labor-intensive process.That encourages farmers to keep re-usingplots for potato cultivation nearer to home.The preferred management strategy is to waituntil yields have fallen to unacceptably lowlevels, then graze livestock on the fallow plotso that manure transport is not an issue.

The unavailability of inorganic fertilizersis a major constraint. It is unlikely that givenUganda's landlocked status, and the distance

of Kabale from Kampala, that fertilizer usecould be undertaken on a large scale with­out being subsidized.

Yet another serious constraint to imple­menting proper agronomic practices is thelack of sufficient quantities of clean seedavailable to farmers. High-quality seed fromKalengyere is sold cheaply to a limited num­ber of contact farmers in the area at a subsi­dized rate. In theory, these farmers multiplyseed and sell it to other farmers in the area.In practice, most of the next harvest is soldoff as ware potatoes for consumption or re­tained by the contact farmer for replanting.Only a few other farmers purchase the newvarieties for seed.

In addition to having insufficient quanti­ties of good-quality seed to start with, farm­ers lack knowledge of how to select and prop­erly store seed. To ensure that the skin of thepotato does not easily peel during storage,stems of the potato plant should be cut off aweek or so before harvest. Many farmers feardoing this, however, as cut stems advertise topotential thieves that potatoes are ready forharvest. Without significant investments infarmer education and improved distributionof high-quality seed, current potato yields arenot sustainable.

Sustainability of Sweetpotato Production

WhiIe farmers widely recogn ize decl in ing soilfertility as a problem, little evidence existslinking deficiencies in swe2tpotatoes withpoor soil fertility. Preliminary research onnutrient deficiencies in sweetpotatoes andconcurrent soil fertility was conducted in Feb­ruary 1996. Leaves were evaluated for criti­cal amounts of macronutrients and micronu­trients. Soil samples were also taken from thebase of each deficient plant at a depth of 15­30 cm.

The major findings from the leaf analyseswere:

• Phosphorus deficiency was very common.• Nitrogen, potassium, and sulfur are also

generally suboptimal.

OP Program Report 1995-96 25

5

9721

1713

90761

7061371136

48371041111

Percentage ofall formers

interviewed

Table 2. Former beliefs abaut late blight and bacterial wilt symptoms, causes, and prevention, Kabale District,Uganda, 1995-96.

26 Progrom]

• Boron concentrations were low to very lowat all but two sites.

Soil analyses frequently showed deficien­cies in P, K, and Ca. Although these resultsare preliminary, because of the limited de­gree of sampling, they reinforce the percep­tion that sweetpotato is increasingly relegatedto soils of declining fertility. Even thoughsomething is produced, yields continue todecline. Moreover, there is an associationbetween increasing severity of the fungal dis­ease Alternaria so/ani and declining soil fer­tility.

The growth of potato in importance as acash crop and for home consumption has, inthe higher elevations of Kabale, displacedsweetpotato in the diet to a certain extent andpushed the crop into more marginal produc­tion areas. However, three facts assure thatsweetpotato will continue to remain an im­portant food security crop in Kabale:

• Sweetpotato is the cheapest source of calo­ries available year-round.

• Sweetpotato outperforms other crops onsoils of declining fertility.

• Sweetpotato is an important rotation cropfor sorghum, maize, beans, and peas.

There are warning signs that sweetpotatoyields will continue to decline. In areas withlittle or no demand for commercialsweetpotatoes, farmers are unlikely to investmany resources in improving the fertility ofmarginal soils on which they prefer to plantsweetpotato. Problems with Alternaria spp.are likely to increase, particularly atthe higherelevations, because of the worsening nutri­tional status of the plant. Although periodicoutbreaks of sweetpotato butterfly (AcraeaacerataJ are likely to continue, they tend tobe local and farmers take group action whensevere infestations occur.

Prospects for market demand to increasebeyond Kabale District are limited.Sweetpotato is widely grown throughoutUganda and higher-quality production areassurround Kampala and other major urban

centers. Increasingly, valley bottom lands andswamplands are being targeted for potato orvegetable production during the dry season.In the past, sweetpotato was planted in themoist valley bottom lands to assure adequatesupplies of planting material for hillside pro­duction the following season.

The evidence suggests that sweetpotatowill continue to be grown in large quantitieson better soils as part of rotation schemes. Inaddition, it will be grown on marginal soilswhere other crops fail, in spite of continualmean yield declines. Overall, yield declinescan be reversed only if non-labor-intensivesolutions to increasing soil fertility are foundor sweetpotato becomes commercially impor­tant, hence increasing the benefit-cost ratioof increased input use.

Research Implications

Declining soil fertility is a major constraint ofincreasing importance to all crop productionin Kabale District. Policy research needs tobe conducted on the cost-effectiveness ofimporting and subsidizing appropriate inor­ganic ferti lizers. It is clear that the limitedavai labi Iity of organic manures and the laborto apply them are likely to remain significantconstraints in the long term. Research effortsshould also concentrate on testing green ma­nure crops that are adapted to higher altitudesand that could be planted on fallow fields.

Unlike the major effort that has been madeon potato, there has been no systematic in­volvement in adaptive testing of sweetpotatovarieties in southwest Uganda. However,given that varietal tolerance of low P levelsand Alternaria spp. exist, it would make senseto test sweetpotato varieties bred by theRwandan national program. During the pasttwo decades, the Rwandan program has bredmany varieties adapted to higher altitudes.Those should still be available.

Finally, the investment in a baseline sur­vey is fully realized only if sites are periodi­cally revisited. Although the selected sites areexcellent for monitoring input use, disease in-

(IP Program Report 1995-96 27

tensification, and potato yields, farmers atthese sites do not possess a significant num­ber of plots with volcanic soils. An additional

28 Program 1

site should be added in the following roundthat would include these volcanic soil typesthat are highly suitable for potato production.

R. Valdivia Alatristal, R. Quirozl, R. Valdivia Fernandez!, andv: Choquehuanca2

Risk Analysis of Potato Production in theAltiplano: Quantifying Farmers' Beliefs

Daily weather data and soils informationfigured as inputs into a process-based, crop­growth model to simulate potato yield. Ge­netic coefficients on potential leaf and tuberexpansion rate, degree of determinacy, pho­toperiod sensitivity, and temperature sensitiv­ity for Imilla Negra and Andina were used tosimulate the performance of the bitter andnonbitter varietal types.

Mixing native and improved potato varietiesin the same field is common. Native varie­ties include bitter (Ruqui, Pinaza, Lok'a, Luki,and Ajanhuiri) and nonbitter (Ccompis, ImillaNegra, Sacampaya, Imilla Blanca, and Cho­quepito) cultivars. Improved varieties are rep­resented by Andina, Tomasa Condemayta,Mariva, and Mi Peru.

ClP Progrom Report 1995-96 29

Farmers were interviewed in 1996 wheninformation on the incidence and conse­quences of risk was canvassed. Farmers rec­ognize four classes of years for potato pro­ductivity: bad, normal, good, and very good.Beliefs on varietal yield were assessed usinga triangular method where the respondentprovided information on the highest, modal,and lowest observations. By multiplying thefrequency of the four productivity events bythe results from the triangular elicitation pro­cedure by varietal type, we generated yielddistributions for native and improved varie­ties.

Yield samples in farmers' fields were col­lected during six growing seasons from 1987to 1992. Stratified sampling by elevation wasused to generate estimated yields for nativeand improved varieties. About 10 fields weresampled in each of the 6 yr.

The incidence and productivity conse­quences of risk are difficu It to assess becausehistorical data on the productivity of fieldsand farms are not available. Nonadoption ofimproved technologies is often attributed torisk, but both subjective and more objectiveinformation is usually lacking to documentthe relative riskiness of competing technolo­gies.

The Altiplano of Peru and Bolivia is home tomany very poor farm families for whom agri­culture is the main source of income. Pota­toes are the staple food crop, and productionrisk, usually in the form of drought and frost,is pervasive.

Nor has the effectiveness of different meth­ods to assess risk been established. In thisstudy, yield and net revenue risk of native andimproved varieties are examined in threeways: (1) estimated yields from samples takenin potato fields, (2) elicited information onfarmer bel iefs about varietal productivity, and(3) simulated yield estimates from process­based, crop-growth models.

This research was conducted in Santa Maria,a community in the Department of Puno,Collao District, Peru. It is situated at about3,900 m above sea level. Land is privatelyand communally farmed.

Potatoes are a dryland crop grown fromOctober to April in the main growing season.

Site and Methods

1 CIP-CONDESAN (Consortium for the SustainableDevelopment of the Andean Ecoregion).

2 CIRNMA-CONDESAN (Centro de Investigaciones deRecursos Naturales y Medio Ambiente, Peru).

for about 98% of the variation in the mea­sured productivity estimates.

Crossing curves imply tradeoffs in risk, thatis, native varieties are less prone to both lowand high yields (Figure 1A). The crop-cutmethod gives results highlighting the stabil­ity of native varieties and the yield respon­siveness of improved varieties to goodweather. In contrast, the farmers' subjectivebeliefs (Figure 1B) show almost no conflictbetween risk and expected productivity. Foralmost all yield levels, improved varietiesdominate. The cumulative probability for astipulated yield level is everywhere higher for

Figure 1 shows the tradeoffs in risk andproductivity and presents the estimated cu­mulative distribution function of yields byvarietal type for each of the three estimationmethods. The cumulative probability reflectsthe likelihood of obtaining a yield less thanor equal to a stipulated level. For example, inFigure 1A, the chance that native varietiesproduce less than 4 t is only about 3%; theexpectation of this very low yield for the im­proved varieties is 10 times more likely at30%.

Improved varieties were also characterizedby the highest mean yields. Differences be­tween the improved and native varietal typeswere most apparent with the measured andelicited methods. In contrast, the simulatedresults gave more or less the same results foreach varietal type.

All methods give productivity estimatessubstantially higher than the departmentalaverage yield of about 5 t/ha for Puno. Thedifference between estimated and officiallyreported yields partially reflects the impactof technological change introduced by theProyecto de Investigaci6n de los SistemasAgropecuarios Andinos in 1985. Healthierseed, improved fertilizer, and other crop man­agement practices played a role in thischange.

The simulated results in Table 1 are espe­cially noteworthy because estimates fromsuch models are often several orders of mag­nitude higher than yields in farmers' fields.In our case, the crop simulation accuratelyreflects reality.

The measured and elicited estimates aresimilar. Indeed, regressing the elicited on themeasured yield data for the 6 years accounts

Results

Yield comparisonsProductivity of the native, improved, and

mixed varietal groups is compared for eachof the three methods of estimation (Table 1).The yield for the mixed varieties was calcu­lated as the average field proportions of na­tive and improved varieties across the 6 years.

We determined risk by comparing yield andnet revenue of native, improved, and mixedvarietal groups.

Table 1. Measured, elicited, and simulated patato yields in Puna, Peru, during the period 1987 through 1992.

30 Progroml

CIP Progrom Report 1995-96 31

Probability (%)100

90

80

70

60

A. Measured50

40

30

20

10

12 16 20 24 28 32

Yield (tlha)

Probability (%)

100

90

80

70

60

B. Elicited50

40

30

20

10

12 16 20 24 28 32

Yield (tlha)

Probability (%)100

90

80

70

60 c. Simulated50

40

30

20

10

0

0 10 11 12 13 14 15 16 17

Yield (tlha)

Figure 1. Estimated cumulative distribution of yield by estimation method. Clp, 1996.

Figure 2. Estimated cumulative distribution of net revenue by estimation method. Clp, 1996.

Probability (%)

100

90

80

70

60A. Measured

50

40

30

20

10

0

'" '" '" '" '" '" '" '" '" '" '" '" '" '" ~~ '".,.

'".,.

'" r-- '" r-- '" r-- '" r--~

(0r-- ~ ~ N "' '".,.

'" '" r-- '" (0 "' '"'" '" '" '".,. .,.

"' "' (0 (0 co

Net income (US$)

Probability (%)100

90

80

70

60

50 B. Elicited

40

30

20

10

00 co (0 :ll (0 (0 (0 (0 co co (0 (0 (0 co co co (0 (0 (0 co coco .,.

'" '" CD CD '" CD '" '" CD '" CD '" '" 0 0 0 a'" r-- ;'! ~ '" (0 a .,. CD '" (0 a .,. CD '" (0 a ;:! CD

'" '" '" '" '" " " "' "' "' (0 (0 r-- r--

Net income (US$)

Probability (%)100

90

80

70

60

50 C. Simulated40

30

20

10

0(J) r-- r-- r-- r-- r-- CD (0 " ;'! " " ;'! CD (0CD II) II) II) II) II) N '" a CD c;; " "~ ~ N II) 0) ;;; " r-- '" N II) 0)

'" N N '" '" " " " " II) II) II)

Net income (US$)

32 Progroml

native compared with improved varieties.Hence, the two methods generate differentresults: in Figure 1A, risk matters; in Figure1B, it does not.

The distributions of the simulated resultsare not that informative. Improved varietiesdominate at almost all yield levels (Figure 1C)and the yield distributions are almost thesame. This similarity suggests that the cropsimulation model is not sufficiently well-de­veloped to assess varietal-specific risk.

Net revenue comparisonsThe higher productivity of improved vari­

eties (Figure 1) does not necessarily translateinto higher net returns. Native varieties com­mand a higher price, and improved varietiesare more intensive users of costly inputs. Pricedifferences between native and improvedvarieties are sharper in better production yearswhen the improved varieties give higheryields.

Figure 2 charts tradeoffs between risk andexpected profitability. The measured and elic­ited results show a slight advantage of nativevarieties over mixtures and improved varie­ties in lower-yielding years. The opposite oc­curs in better years when pure stands of im­proved varieties are superior to native varie­ties or mixtures.

Conclusions

Direct elicitation of the subjective incidenceand severity of risk in potato production wasuseful in incorporating farmers' knowledge.It also gave results comparable to the moretedious objective method of sampling yieldsover time. This result suggests that farmers'knowledge might be successfully used to es­timate potato yields over time with accept­able precision. Moreover, the estimated vari­ance of the reported yields appears to be re­liable and useful for assessing production risk.

Simulation models also gave results con­sistent with mean levels of productivity, butsuch tools are still too immature to describevariety-specific risk, the subject of this study.Experimentation in both bad and good yearsis needed to recalibrate these models to re­flect the reality of the harsh production con­ditions of the Altiplano.

More research is also needed to under­stand the dynamics of varietal mixtures in risk­prone environments. In general, our resultssuggest that risk is an important issue for po­tato producers in the Altiplano. Native vari­eties are more profitable in lower-yieldingyears, and improved cultivars are more prof­itable in better years.

(IP Program Report 1995-96 33

F. Terrazas!, V. Suarez2, G. Watson3

, G. Thiele!,T. Walker, and A. Devauxl

Analyzing Potato Productivity inFarmers' Fields in Bolivia

ernmental agencies and nongovernmental or­ganizations in March, April, and May duringthe harvest from the main growing season, orsiembra grande, which is planted in Octoberand November at the beginning of the rainyseason. Information was elicited in a ques­tionnaire on potato production practices, andtwo yield samples from a field ready for har­vest were taken. The multiyear data set con­tains 1,897 field and farmer observations dis­tributed across 1,250 communities in 36 prov­inces.

The mean sample yield was 10.5 t/ha rang­ing from 400 kg to a maximum of 40 t/ha (Fig­ure 1). The intervals between 2.5 and 10.0t/ha accounted for the bulk of the observa­tions in Figure 1. The empirical distributionof yields in Figure 1 is positively skewed,which is typical of semisubsistence small­holder agriculture in rustic production con­ditions.

Assessing Potato Productivity

The crop-cut estimates imply a fairly lowlevel of productivity, but they are about twiceas high as official departmental estimates,which varied from 4.5 to 6.5 t/ha in the early1990s. Crop-cut estimates also convey sub­stantially higher levels of productivity thanmultiplication ratios of output harvested to tu­ber seed planted, which is the way small farm­ers usually express productivity in potatoes.When asked how much production they ex­pected per unit of seed planted in the sampledfield, farmers most frequently gave multipli­cation ratios of 2.0 to 6.0. If we assume a seedrate of 1.5 t/ha, then a mean estimated yieldof 10.5 t/ha is consistent with a multiplica­tion ratio of 7.0.

Potatoes are the staple food crop in the Andesof Bolivia. Potato production and postharvestactivities are a major source of rural employ­ment and household income. Assisted byfunding from the government of Switzerland,the government of Bolivia in 1989 strength­ened its commitment to potato crop improve­ment, which was institutionally reborn in theform of the Proyecto de Investigaci6n de laPapa (PROINPA).

The population of interest in this study onpotato productivity in farmers' fields encom­passes potato producers in four departmentsof Bolivia: Cochabamba, Chuquisaca, POtOSI,and Tarija. These departments were the ar­eas where PROINPA was most active in theearly 1990s. Cochabamba was surveyed in1990, 1991, and 1992, Chuquisaca in 1990and 1991, POtOSI in 1990 and 1991, and Tarijain 1992, 1993, and 1994.

Diagnostic research on constraints to andopportunities to increase potato productionwas symptomatic of the renewed vigor of thenational potato program in the 1990s. Pro­duction surveys in the early 1990s were animportant part of this diagnostic effort. Be­cause of their broad coverage in more than1,000 communities and because of their de­tailed, highly focused questions on potato pro­duction practices, these surveys are a richsource of information on potato productivityin farmers' fields.

1 PROINPA, Cochabamba, Bolivia.2 CIP, Lima, Peru.3 Formerly PROINPA.

The production surveys were conductedby research and extension staff of both gov-

34 Progroml

1.25 3.75 6.25 8.75 11.25 13.75 16.25 18.7521.2523.7526.2528.7531.2533.7536.2538.75 41.25 43.75 46.25 48.75

Frequency intervals (tlha)

(IP Program Report 1995-96 35

Estimated field size ranged from tiny, al­most garden-size, to relatively small. The me­dian size was between 0.1 0 and 0.25 ha; onlyabout 10% of the fields exceeded 0.50 ha.

Potatoes are grown in Bolivia high in theAndes, often on steeply sloping fields. Themedian elevation was between 3,000 and3,500 m; about one-third ofthe sampled fieldswere above 3,500 m. The most frequent slopecategory was between 3% and 20%, butmany fields (33% of the sample) were onslopes exceeding 20%.

Although potatoes are mainly a drylandcrop, about 30% of the fields were reportedto have benefited from irrigation during thegrowing season. The incidence of irrigatedfields was higher than expected, but irriga­tion should not convey the image of large­farm, commercial potato production.

Irrigation is negatively associated with fieldsize. About 35% of the 346 fields estimated

•It

• l

I

4l

l~

TTi,,.._ •. __

Describing Potato Production

Figure 1. Frequency distribution of estimated yields. Numbers on x axis indicate midpoints of each frequencyinterval. For example, the first interval contains observations from 0.00 to 2.49, the second from 2.50 to4.99, etc.

o

50

100

150

200

250

300

350

400

Observations (no.)

The difference in the size of these two pro­ductivity measures is probably attributed topotato quality. In crop cuts, all potatoes areharvested and weighed. When farmers ex­press multiplication ratios, they may be fo­cusing on production of a specified size andshape. They may also be discounting potatodamaged by Andean potato weevilPremnotrypes spp. Nonetheless, the crop-cutdata indicate that farmers' yield estimates arelikely to be substantially lower than actualproductivity.

Potato production in Bolivia in the early1990s was still very much a semisubsistenceactivity. Small farm households cultivatedpotatoes in very small fields with a low levelof agricultural intensification. About one-halfof the respondents stated that the productionof the field was exclusively for householdconsumption. Only about 15% indicated thatthe bulk of production would be sold.

to be smaller than 0.1 0 ha were irrigated; only14% of the 127 fields estimated to be largerthan 0.50 ha were irrigated.

Nine often potato fields received manure.Sheep droppings were the dominant sourceof organic amendment. The importance ofmanuring is underscored by the observationthat about one-quarter of the fields benefitedfrom two kinds of livestock manure.

Fewer but sti II a majority (63%) of farmersapplied inorganic fertilizer, usually in theform of NPK 18-46-0 or urea. Chemical fer­tilizer was used sparingly, never more than afew bags per field.

I

Fallowing land three or more years beforeplanting potatoes occurred on 36% of thesampled fields. Potato monoculture, featur­ing three prior consecutive potato crops, wasrare. In general, the farmers' responses oncrop rotation support the conventional wis­dom that potato is often the first crop to beplanted following a period of fallow.

Pesticides are not used intensively in po­tato, but about two-thirds of the fields weresprayed or dusted. The modal number of ap­plications was two to three on those fields.Only 5% of the fields received more than foursprays.

The formal sector did not loom large as aseed source. Nor was the incidence of spe­cialized seed producers high. Nine of tenfarmers stated that they planned to produceseed for their own use from the sampled field.Relatively few respondents (6%) said that pro­duction from the field wou Id be sold as seed.

The dominant clones planted in thesampled fields were local varieties, which areoverwhelmingly Solanum andigena (short­daylength Andean) types. About 1 field in 10was planted to an introduced variety, such asRevoluci6n (Peru) or Alpha (the Netherlandsvia Chile).

Although information on varietal choiceconveys a rich array of varietal diversity, a

36 Program!

relatively few varieties accounted for a sub­stantial proportion of the dominant varietiesin the crop-cut fields. For example, Waych'awas listed as the leading variety in 220 fields,and Sani Imilla was recorded as the domi­nant variety in 200 fields. The fields wereabout evenly split between those in whichvarietal monocu Iture was practiced and thosein which more than one variety was planted.

Explaining Yield Variation

Differences in yield in the sample fields re­flect variation in household resource endow­ments, institutional access and participation,field attributes, management practices,weather during the growing season, biotic andabiotic stresses, and cropping history. Figure2 illustrates these relations. The boxes denotepredetermined variables that influence yieldnot only directly but also indirectly throughthe intervening variables described in circles.Quantifying the relations in Figure 2 is a com­plex undertaking that requires information onthe timing of production processes.

In an exploratory analysis, the bulletedvariables in Figure 2 were correlated withyield in a multivariate regression framework.Figure 3 presents the statistically significant(P<.05) results in a productivity gap format,which depicts the change in estimated yieldwith a change in the variable of interest, whileall other variables are held constant.

Changing the base conditions one at a timefor the statistically significant managementvariables gives incremental yield increaseestimates from a base yield of 6.8 t/ha to thehighest forecast yield of 18.6 t/ha.

Figure 3 is based on an analysis of the fulldata set pooled across the departments ofCochabamba, Chuquisaca, Potosi, and Tarija.The estimated response of several of the in­dependent variables varied significantly bydepartment; therefore, Figure 3 summarizesonly information on general tendencies.

Of all the potential variables in Figure 2,the impact of pesticides on productivity was

Figure 2. Schematic representation of interrelations determining productivity with data from the Bolivian pototoproduction survey.

Field• Slope• Altitude• Province• Distance

to a road

About one-quarter of the farmers said thatthey received technical assistance in potatoproduction in the form of training and infor­mation, credit, or access to inputs. The esti­mated effect of technical assistance was 2.5t/ha (Figure 3).

(IP Program Report 1995-96 37

In an effort to better understand the nexusbetween technical assistance and potato pro­ductivity, credit-related technical assistancewas grouped separately from non-credit-re­lated technical assistance. When technicalassistance was disaggregated into these twogroupings and the regression model was re­estimated, the coefficients suggested thattechnical assistance was broadly effective inincreasing potato productivity independent ofthe type of service offered. Although thosefarmers who received technical assistancemay have had higher yields than other farm­ers for reasons other than technical assistance

the most consistent across the four depart­ments. Pesticide application was accompa­nied by a 2.6 t/ha increase (Figure 3). At lev­els of intensification in the early 1990s, fewpotato growers overused pesticides. But withsuch transparent productivity benefits, the useof such chemicals will likely expand in thefuture.

More analysis of the effects of differentpesticides showed that systemic insecticidesand fungicides and nonsystemic insecticidesmade an important and statistically significantcontribution to yield. Nonsystemic fungicidesdid not significantly change productivity. Thisfinding points to the potential for more effec­tive use of chemicals in the integrated man­agement of late blight caused by the fungusPhytophthora infestans, the target of the bu Ikof fungicide appl ication in potato productionin Bolivia.

tlha

Base conditions

• Male respondent• Cochabamba (Arani)• Planted on time• No technical assistance• < 1.0 km from a road• 3,000-3,499 m• 3-20% slope• Dryland• Owner-operated• Insufficient seed• Native varieties• Noninstitutional seed source• Continuous cropping• Unmechanized• No pesticides• No chemical fertilizers• Manured

Pesticides

Technical assistance

3-year fallow

Sufficient seed

Chemical fertilizer

Institutional seed source

Irrigation

Farmers who believed that they had suffi­cient seed to plant their planned potato area

Most farmers who used pesticides alsoused chemical fertilizer, but its impact onyield was not as strong as that of pesticides.The use of chemical fertilizer was associatedwith a yield increase of only 1.4 t/ha. Lowrates of application may partially explain thisless-than-expected yield response.

9.4

6.8

11.9

15.1

16.4

13.7

17.5

18.6

Base yield

Highestpredicted yield

o

5

10

15

20

Fallowing two or more years was associ­ated with a large and statistically significantyield advantage over continuous cropping(Figure 3). The productivity effects of a longerfallow were especially marked in Tarija andCochabamba.

per se, the results support the case for invest­ing in extension programs designed to en­hance potato productivity.

Figure 3. Sources of variation in potato productivity in farmers' fields in Bolivia.

38 Program 1

had 1.3 t/ha higher yields than those whobelieved that they did not have enough tuberseed. Although this question was cast in termsof seed availability, the strength of the resultssuggests that the responses are indicative ofseed quality.

About 10% of the farmers benefited froman institutional supply of seed, which was theoriginal source of the variety planted in thefield. Switching from an informal to an insti­tutional source of the variety was accompa­nied by a statistically significant 1.1 t/ha yieldincrease. This effect was most pronouncedin Cochabamba. Collectively, the results onseed sufficiency and institutional seed sourcepoint to productivity benefits of improvingseed quality and availability.

The impact of irrigation on potato produc­tivity was not nearly as large as anticipated.Irrigation increased potato yield by only 1.1t/ha. The positive productivity impact of irri­gation is largely driven by the results inChuquisaca where yields in irrigated fieldswere 2.5 t/ha higher than in nonirrigatedfields. No data were taken on the intensity ofirrigation; therefore, it is hard to explain theinterdepartmental variation in this result.

The consequences for productivity of sev­eral other variables, which are described inFigure 2 and subsumed in the baseline sce­nario in Figure 3, warrant comment. Estimatedyields in fields farmed by women were notsignificantly different from estimated yields

in fields farmed by men. Owner-operatorfields were characterized by a yield advan­tage of about 1.0 t/ha compared with fieldsfarmed by groups. This yield difference is netof the effect that fields being farmed by agroup were more likely to be planted laterthan fields cultivated by a single household.Fields planted after mid-November yielded1.0 t/ha less than those planted before thatdate. A group was also more likely to per­ceive a seed shortage.

Summing Up

Like other survey-based research, this workhas begged more questions than it has an­swered. For example, reasons for the absenceof an anticipated strong productivity responsebetween supplementary irrigation and chemi­cal fertilizer use need to be investigated.Moreover, gathering more household-specificinformation, particularly on assets, could havecontributed to a deeper understanding of ex­planations for variations in productivity acrossfarmers' fields.

Nonetheless, the production surveys werecost-effective in generating insight into thelevel and determinants of potato productionin Bolivia. They also provide a valuablebenchmark for impact assessment of tech­nologies generated by PROINPA. Combiningcrop cuts and focused surveys with broad geo­graphic coverage should receive more em­phasis in diagnostic research on productivityconstraints and opportunities.

[IP Program Report 1995-96 39

Preferences of Urban Consumers forAndean Roots and Tubers in Ecuador

P. Espinoza A. and c.c. Crissman1

Limited and declining demand by urban con­sumers is often cited as a major constraint toexpanding the use of ulluco (Ullucustuberosus), arracacha (Arracacia xanthorrhiza),oca (Oxalis tuberosa), and mashua (Tropaeolumtuberosum). Like potatoes, these are root andtuber crops domesticated in the Andes. Ofthe lesser-known Andean root and tuber crops(ARTC), the first three are the most important

economically in Ecuador. But their consumeracceptance in large metropolitan areas ingeneral, and the scope for identifying marketniches to increase consumption in particu­lar, have not been investigated. Ecuador, likethe rest of the Andean countries where thesecrops are part of the diet, is already a pre­dominantly urban country and will becomeeven more so in the future.

To address these issues, two types of in­quiries were carried out. First, 770 consum­ers, selected randomly and stratified bywealth, were interviewed about their con­sumption of and preferences for ulluco,arracacha, oca, and mashua.

Respondents were residents of Quito,Guayaquil, and Cuenca, the three largest cit­ies, which account for 30% of the popula­tion of this country of 11 million inhabitants.Second, consumer panels of 160 residents ofQuito were formed to test the acceptabilityof distinct types of ulluco and arracacha.

Urban Consumption of AndeanRoots and Tubers

Over 90% of the respondents in each of thethree cities recognized and had previouslyconsumed ulluco and arracacha. In contrast,knowledge of and prior experience with

1 ClP, Quito, Ecuador.

40 Progroml

mashua was negligible. Most respondentsfrom the Andean cities of Quito and Cuencahad consumed oca, but few from the coastalcity of Guayaquil had ever eaten it.

Urban Ecuadorians consume a variety ofroot and tuber crops. Table 1 shows estimatedannual purchases per person; this includespotato, cassava, and sweetpotato. Across thethree cities, ulluco and arracacha rank thirdand fourth in per capita annual purchases ofroot and tuber crops, but they are a distantthird and fourth in quantity purchased. Po­tato occupies a dominant position in Quitoand Cuenca, and potato and cassava are themost economically important root and tubercrops in Guayaquil.

Surprisingly, per capita purchases of ullucoand arracacha are higher in coastalGuayaquil, which is farther from their source,than in the Andean cities of Quito andCuenca.

The lesser-known ARTC are usually asso­ciated with poverty in both production andconsumption. Poorer respondents tended topurchase proportionally more ulluco and oca.In contrast, the wealthiest respondents boughtrelatively more arracacha, which is especiallyprized by richer consumers in Guayaquil.

The survey results also support the con­ventional wisdom that consumer preferencefor these crops is declining (Table 2). Sub­stantially more respondents stated that in thepast they had consumed more ulluco,arracacha, and oca, compared with potato,than they do now. Moreover, preferences forthese crops varied by age. On average, thehighest preference scores were given by theoldest group of respondents and the lowest

Positive and negative characteristics,which condition consumer preferences, areunique to each of the three crops (Table 3).Ulluco was negatively associated with a highincidence of mucilage. Oca took too long toprepare. Negative aspects related to smell andtaste eroded consumer preferences forarracacha. On the plus side, the three cropswere widely viewed as nutritious. The easydigestibility of arracacha leads to its frequentuse as baby food or for nursing mothers.

The limited availability of morphotypes is asevere constraint to expanding urban con-

Morphotype Variability in Consumption

by the youngest. This pattern did not prevailin potatoes, where average preference scoreswere uniformly high across age groups.

(IP Program Report 1995-96 41

Table 1. Annual per capita purchase (in kg) of root and tuber commodities (n=770) in three Ecuodorian cities,1994-95.

These lesser-known ARTC are also viewedas being cheaper than potatoes. Indeed, theresults of the survey support this perceptionamong respondent households.

Potatoes were perceived to be dearer thanother root and tuber crops. But market infor­mation suggests the opposite: ulluco,arracacha, and oca all cost more per ki logramthan potato. Perhaps consumers confusedexpenditure with unit prices in responding tothe question on relative prices.

Table 2. Variation in consumption of roots ond tubers over time by commodity in percent (n=770), CIP-Ecuador,1994-95.

Table 3. Positive and negative characteristics that condition preferences lor lesser-known Andean root and tubercommodities, CIP-Ecuador, 1994-95.

Implications for ExpandingUrban Consumption

Protecting the biodiversity of these lesser­known ARTC requires the maintenance ofexisting markets and the development of newmarkets. Like most Latin American countries,Ecuador is predominantly urban. Urban mar­kets are therefore essential to the survival of

For arracacha, differences in perceivedcharacteristics between the top two rankingmorphotypes were not as marked as in ulluco.Consumers were impressed with the brightcolor of the yellow morphotype, and theyrated its taste, smell, and consistency on a .par with the white one.

tive with the white one in arracacha. Thestrength of the pink ulluco was its lower mu­d lage content; the yellow arracacha was pre­ferred for its bright color, which it kept whencooked. There were no significant differencesin acceptability for yellow and pink ulluco.

Is the absence of these other morphotypesin the market attributable to poor consumeracceptability or lack of availability? To an­swer that question, consumer panels weregiven an array of morphotypes of ulluco andarracacha to consume and evaluate in theways they normally would prepare them.

The results (Table 5) indicate that the pinkmorphotype is broadly acceptable in ullucoand that the yellow morphotype is competi-

A similar situation occurred in the con­sumption of arracacha, which is identifiedwith the white morphotype. Urban consum­ers had never seen yellow and purplemorphotypes.

sumption of ulluco and arracacha. The ma­jority of consumers in Quito identified ullucowith the dominant yellow form (Table 4). Theyhad never seen other morphotypes. InGuayaquil, the red ulluco prevailed, and inCuenca yet a third type dominated the market.

42 Progrom 1

(%)

96.7

Cuenca

(IP Progrom Report 1995-96 43

Gal litoPink

Yellow

6.68 (0)6.56 (0)6.06 (b)5.97 (be)

8.94.0

Guayaquil

Based on the survey and subsequent con­sumer panel results, implications for increas­ing urban consumption are specific to eachcrop. Oca is still widely appreciated in ruralregions, yet is largely unknown in the cities.We can draw on the experience of reintro­ducing quinua in several countries in LatinAmerica and sweetpotato in Chile for a pro­motion strategy for oca. Promoting it as anexotic and organic product to richer consum­ers first would appear to be the most suitablestrategy to increase urban demand, whicheventually wou Id percolate to poorer con­sumers.

YellowGal lito

Pink

2.21.1

YellowPinkWhite

Quito

Gallo L1iro

Gal lito

Red

these crops. This urban population is grow­ing rapidly from natural birth rates and fromrural-urban migration. Most migrants comefrom lower economic strata and bring withthem their ARTC consumption habits. How­ever, notable was the fact that preferences forulluco and arracacha by the upper economicstrata exceeded those of the lower strata.These two crops do not need to be consignedto market niches for poor people. By takingadvantage of the knowledge of the urbanpopulation of these crops and preferences forthem, new niches can be found that can helpassure the survival of distinct morphotypes.

Table 5. Mean acceptability scores of different morphotypes of ulluco and arracacha'.

Table 4. Consumer preference for ulluco morphotypes in three Ecuadorian cities.

Many respondents, particularly youngerpeople in Quito, reject ulluco because of thehigh mucilage content of the yellowmorphotype, which is the only one marketedin the city. The results of the consumer panelshowed that a market niche exists for a pinkmorphotype with less mucilage.

In general, consumers prefer bright-col­ored morphotypes that are low in mucilageand that keep their color during preparation.These types should be promoted so that con­sumers can select between ullucomorphotypes that are high and low in muci­lage content.

Similarly, most consumers know only onemorphotype (white) of arracacha. Again, the

44 Program 1

consumer panel study pointed to the marketpotential of the yellow morphotype, whichwas praised for its color and taste. Addition­ally, improving the transport and packing ofarracacha destined for the Guayaquil marketcould lead to an increase in consumption inresponse to a better presentation and longershelf life.

For more details on these crops, includingrecipes, see: Espinosa and Crissman, Rakesy Tuberculos Andinos en Ecuador, EdicionesAbya Yala, Quito, Ecuador, in press, and P.Espinosa, R. Vaca, J. Abad, and C. Crissman,Rakes y Tuberculos Marginalizados en Ec­uador: Limitaciones en Producci6n, EdicionesAbya Yala, Quito, Ecuador, 1997. 179 p. Bothare available through CIP.

II-Gin Mok, Lisna Ningsih, and TjintokohadP

Selection of New Sweetpotato Varietiesfor High Dry Matter Content in Indonesia

Results and Discussion

CIP Progrom Report 1995-96 45

Storage-root yieldAlthough clones used in the study were

initially selected at Bogor for high OM con­tent and high yield, many of them also hadhigh yields at Lembang and Malang. AtLembang, the average yield of the check BIS183 was about 20 t/ha. Therefore, clones se­lected for Lembang had to yield more than20 t/ha, and have OM content above 35%,which commercial processors prefer. AtMalang, cv. Pak Ong yielded 32 t/ha. Only afew clones yielded as high as or higher thanPak Ong, but all were higher in OM content.OM content of Pak Ong was only 24.5%.

OM content was measured by selectingfive medium-size storage roots from each plot,and chopping them into thin strips. One hun­dred g of sample were oven-dried at 105°Cuntil weight remained constant.

Storage roots harvested from Lembangwere used to measure starch content. A simplemethod was used to extract starch in the labo­ratory. The storage root was chopped, groundin a blender, sieved through a 150-200 meshscreen, and allowed to sediment for 3-4 hbefore drying.

Farmers use high levels of N fertilizer (100kg/hal. At Malang, we used farmers' fields,and asked them to manage the crop accord­ing to their own practices, to minimize anyinfluence from us except for our providingplanting material. The climate at Bogor is hotand humid, and soil fertility is low. We didnot apply fertilizer, relying instead on residualfertility from the previous crop. Yield and OMcontent were compared at all three sites.

Meanwhile, botanical seeds introducedfrom various sources, including OP-Lima andCIP's regional breeding programs, and frombreeding programs in China, Japan, and thePhilippines (Table 1), have been intensivelyevaluated and selected at Bogor. From 1993to 1995, about 90 advanced clones were se­lected for high OM content and high yield atBogor. These clones were tested at Lembangand Malang to select the most suitable vari­ety for starch production for Southeast Asia.These advanced clones also maintain manyuseful traits such as resistance to scab (causedby E/sinoe batatas), white or cream flesh, andgood storage-root shape. These advancedclones were a result of many years' efforts toselect a variety for high OM content.

Lembang is situated at about 1,600 m abovesea level. Because the average temperatureis low (16-24°C), the sweetpotato growingseason is 5-6 mo from planting to harvest. Ni­trogen ferti Iizer was appl ied at the rate of 60kg/ha. Malang is situated at about 500 m,where the growing season is about 4 mo.

1 CI P-ESEAP regional office, Bogar, Indonesia.

Materials and Methods

Increasing dry matter (OM) content is the pri­mary objective for sweetpotato breeding forSoutheast Asia. Since 1990, many CIP patho­gen-tested clones have been eval uated inBogor and at other sites in Indonesia. How­ever, their low OM content or poor adapt­ability outweighed their good agronomiccharacters. We are now combining this OPgermplasm with locally important cultivars ina recurrent selection scheme for long-termpopulation improvement in Indonesia.

.)

95

116311

o3754

Acronyms, p.

53186338785

We estimate that the clones would produce4.6-6.6 t/ha of starch at Lembang, and 6.6­7.7 t/ha at Malang (Table 3). Assuming anextractable starch content of 25%, and yield

Starch contentStarch content varied from 20% to 30%

(Figure 2). Most clones tested had between20% and 25% starch content. Seven cloneswere in the range of 25.1-27.5%; one clonehad a starch content of 30%. Starch contenton a dry wt basis ranged from 58.9% to77.9%, av 69.1 %. The correlation coefficientbetween OM content and starch content was0.689 in Lembang, which is highly significantat the 0.01 probability level.

Based on overall performance, the fourbest clones (Table 2) were selected for starchprocessing. AB94001.8 is a selection fromJapanese seed fami Iies; the other three clonesare from CIP's seed families. All are highyielding, and are high in OM and starch con­tent. They are highly or moderately resistantto scab, which is important in Southeast Asiancountries.

374

Families evaluatedat Bogar (no.)

Since Pak Ong is used to make ketchup andsambel (chili paste made from sweetpotatoand hot pepper), there is a strong demand fora variety with higher OM content.

There is a highly significant correlationbetween OM content in different environ­ments. The correlation coefficient for OMcontent between Lembang and Malang was0.536 (with df = 30, significant at the 0.01probability level). If a clone is high in OMcontent at Lembang, it is likely to be high atMalang as well, although their environmentsdiffer considerably.

Dry matter contentFigure 1 shows the frequency distribution

of OM content for advanced breeding clonesevaluated at Lembang and Malang. At bothsites, many advanced breeding clones hadhigh OM content. Most of the clones testedhad OM content above 30%. The number ofclones with OM content above 35% was 21at Lembang and 17 at Malang. The result in­dicates significant progress in breeding forhigh OM content.

Table 1. Origin of odvonced clones selected at Bogor in 1993-95. All materials were initially introduced asbotanical seed.

46 Progroml

Starch (%)

Dry matter (%)

There is a very high correlation betweenstarch content and DM content. Heritability

Conclusions

(IP Progrom Report 1995-96 47

$=20

Clones (no.)

Mj

I45 ....:.A..:..-----==I==~~ -, ,a:i,-

$=20 20.1- 25.1- 30.1- 35.1- 40.1-

25 30 35 40 45

Clones (no.)

:~blJi1I,_I$=20 20.1- 22.6- 25.1- 27.6-

22.5 25 27.5 30

Dry matter (%)

Clones (no.)

:~ll-----B,",. ,U, I20.1- 25.1- 30.1- 35.1- 40.1-

25 30 35 40 45

Figure 2. Frequency distribution of starch content for advanced breeding clones evaluated at lembang (1600 m),Indonesia, 1996.

of 20 t/ha, 5 t of starch could be producedfrom 1 ha in 4 mo. That would be competi­tive with other crops in the starch processingindustry in Southeast Asia.

Figure 1. Frequency distribution of dry matter content for advanced breeding clones evaluated at (A) lembang(1600 m) and (8) Malang (500 m), Indonesia, 1996.

Flesh

color

7.72

Molang

(ream White(ream White

Red White(ream White

0.025.127.0

Starch Skin

content color

(%)

lembang

6.58

lembang

(t/ha)

33.836.736.0

40.438.8

OM

34.8

content

(%)

content

(%)

rent selection to rapidly accumulate usefulgenes for high starch content into a popula­tion. Botanical seeds from the population arethen distributed to collaborating institutes forfurther selection in each country.

Malang Bogar lembang

content is also high. Therefore, it is reason­able to expect rapid enough genetic advanceto select for high starch content in a short pe­riod.

Because we are dealing with diverse envi­ronments, we are using polycross and recur-

48 P,ogmm 1

Table 3. Starch productivity at lembang and Malang calculated fram starch content of clones grown at lembang,Indonesia, 1996.

Table 2. Four best-performing clones selected from 90 advanced clones for high dry matter content and yield,Indonesia, 1996.

E.B. Carey!, S.T. Gichuki!, P.J. Ndolo2, G. Turyamureeba3,

R. Kapinga4, N.B. LutaladioS, and J.M. Teri6

Collaborative Sweetpotato Breeding inEastern, Central, and Southern Africa

for future emphasis are proposed. First, weplace regional breeding efforts in context byreviewing some aspects of currentsweetpotato production and constraints.

The crop is grown principally for its stor­age roots, which are usually harvested eitherpiecemeal or progressively, and eaten fresh,either boiled or steamed. In much of south­ern Africa, including Tanzania, the leaves arealso eaten as a vegetable.

CIP Program Report 1995-96 49

In eastern, central, and southern Africa,sweetpotato is generally grown for householdfood, with minimum use of inputs other thanlabor. It is usually a women's crop. In addi­tion to providing food, it is also often sold inlocal markets to generate small amounts ofcash. In a few areas, the crop is grown com­mercially on a relatively large scale for saleto urban markets. Low-input production prac­tices, however, are still the norm because ofrisks associated with low prices caused bymarket gluts at harvest.

Status of Sweetpotato Production andConstraints in the Region

In eastern Africa, particularly in denselypopulated areas of Kenya with high produc­tion potential, vines are sometimes fed tocattle. In some dry areas of Tanzania andUganda, sun-dried products made from stor­age roots provide a seasonally important di­etary staple. There is essentially no use of thecrop as a source of marketable products suchas starch, flour, or animal feed.

Farmers in the region grow a large num­ber of varieties, principally disseminatedthrough informal farmer-to-farmer exchange.

This report focuses on recent progress andcurrent approaches to sweetpotato variety se­lection and dissemination activities in the re­gion. For illustrative purposes, emphasis isgiven to data collected in Kenya.

1 CIP, Nairobi, Kenya.2 Kenya Agricultural Research Institute (KARl), RRC­

Kakamega, Kakamega, Kenya.3 National Agricultural Research Organization, Namulonge

Agricultural and Animal Production Research Institute(NAARI), Kampala, Uganda.

4 Agricultural Research Institute-Ukiriguru, Mwanza,Tanzania.

5 Programme Regional de l'Amelioration de la Culture de laPomme de Terre et de la Patate Douce en AfriqueCentrale et de l'Est (PRAPACE), Kampala, Uganda.

6 Southern Africa Root Crop Research Network (SARRNET),Lilongwe, Malawi.

Principal breeding objectives and strate­gies are discussed, and areas and approaches

.Over the past few years, sweetpotato researchand development efforts in eastern, central,and southern Africa have intensified mark­edly. This regional effort is carried out largelyby national programs under the auspices oftwo regional research networks, theProgramme Regional de I'Amel ioration de laCulture de la Pomme de Terre et de la PatateDouce en Afrique Centrale et de l'Est(PRAPACE) and the Southern Africa Root CropResearch Network (SARRNET), with techni­cal assistance from CIP. Varietal improvementprograms aim to enhance the value of thecrop for food security through the selectionand dissemination of early high-yielding va­rieties with acceptable quality adapted to themajor sweetpotato-producing environmentsin the region. Breeding efforts also link topostharvest research and development effortsaimed at diversifying uses of sweetpotato toexpand income-generating opportunities forfarmers and processors.

Some constraints are common tosweetpotato across all AEZ. The prevalenceof late-maturing, low-yielding varieties grownby farmers is widely considered to be a ma­jor constraint to increased production. Lim­ited forms of use and the perishabi lity of freshroots also seriously limit demand forsweetpotato in the region. The potential fordiversification of sweetpotato uses has not

Generally adequate levels of resistance tosweetpotato virus disease (SPVD) and Alter­naria stem blight caused by Alternaria spp.occur in most important varieties in AEZwhere these constraints are important. Theimportance of these constraints usually be­comes especially apparent during the selec­tion of new varieties.

eties and the relatively rapid turnover of vari­eties observed in some areas.

Sweetpotato is grown over a wide rangeof environments in the region, but most isgrown at mid-elevations between 800 and2000 m. These mid-elevation production ar­eas may be roughly divided into three majoragroecological zones (AEZ), each having adifferent set of commonly occurring con­straints to increased production. The majorAEZ, their major areas of distribution, andconstraints are shown in Table 1.

Only in South Africa and Zimbabwe arethere schemes for the relatively limited dis­semination of pathogen-tested planting ma­terial of selected varieties to commercial farm­ers.

Throughout the region, the crop is propa­gated using vine cuttings, principally obtainedfrom previous crops or in drier areas frommultiplication plots maintained in swampyareas or in the shade of trees.

In general, farmers attempt to selecthealthy-appearing planting material of knownvarieties. But in times of scarcity, they go somedistance to obtain planting materials of un­known varieties of possibly poor health sta­tus. The general lack of attention by farmersto the storage-root production of the plantsfrom which they select planting materials maycontribute to the degeneration of some vari-

Table 1. Distribution of major sweetpotato agroecologicol zones in eastern and southern Africa, and associatedproduction constraints.

Many have probably been selected by farm­ers from chance seedlings, which develop fre­quently because many sweetpotato varietiesflower readily under short-daylength tropicalconditions. The informal nature of variety dis­semination and the lack of information on va­rieties grown by farmers make it difficu It todetermine the extent to which relatively re­cent introductions or escapes from breedingprograms contribute to the mix.

50 Progrom 1

been as widely recognized by farmers andresearchers in Africa as in a number of Asiancountries. Where use is diversified,sweetpotato has gone from being predomi­nantly a food security crop to being an in­come generator as a raw material for humanfood and animal feed products. Similarly, lowor declining soil fertility is widespread acrosslarge areas of eastern, central, and southernAfrica where sweetpotato is grown. It is es­pecially severe in the densely populated cen­tral African highlands.

Current Approaches and Selected Results

During the past few years, there has been anincreasing sweetpotato research effort in east­ern, central, and southern Africa. The workhas largely been conducted under the aus­pices of PRAPACE and SARRNET, with sup­port from ClP, through a regionally based teamof scientists in key countries. The CIP teamincludes a plant breeder, an entomologist, apostharvest specialist, and socioeconomists.The breed ing component of the effort, wh ichis still evolving, is highly collaborative, prin­cipally involving shared breeding trials withthe national programs of Kenya, Uganda, andTanzania, and broader regional evaluationsthrough the networks.

Key elements of the regional breeding strat­egy include: (1) the introduction and testingof elite varieties and seed populations fromoutside of Africa; (2) the cleanup, distribu­tion, and testing within Africa of varietiesidentified as promising or important by indi­vidual national programs; (3) breeding in keyAEZ to generate new varieties for the region;and (4) the participation of farmers and ex­tension and nongovernmental organ ization(NCO) partners in the selection and dissemi­nation of new varieties.

Within each network, some countries playmore active roles than others in sweetpotatovariety development. Thus, in PRAPACE (anetwork of Burundi, Eritrea, Ethiopia, Kenya,Rwanda, Uganda, and Zaire), Kenya, Ethio­pia, Uganda, and Zaire have taken varietyselection, particularly for virus resistance andearliness, as their main area of focus. In

SARRNET, an 11-country network of Angola,Botswana, Lesotho, Malawi, Mozambique,Namibia, South Africa, Swaziland, Tanzania,Zambia, and Zimbabwe, breeding new vari­eties is the focus of Malawi, Mozambique,South Africa, Tanzania, and Zambia. Othercountries, both within and outside of the net­works, principally receive and test provenvarieties identified by the lead network coun­tries.

In recent years, ClP has been the principalprovider of pathogen-tested sweetpotatoclones for distribution in the region. Interna­tional distribution of seed populations is an­other important means of introducingsweetpotato germplasm for selection bybreeding programs.

Principal sources of sweetpotato seedpopu lations distributed recently in the regionhave included the ClP breeding programs inPeru and Indonesia, the Chinese programs atXuzhou and Guangzhou, and programs atMississippi State University and the UnitedStates Department of Agriculture VegetableResearch Laboratory at Charleston, SouthCarolina. Until 1994, the Institut des SciencesAgronomiques du Rwanda maintained acrossing block, which was an importantsource of seed for distribution within andoutside of Africa. More recently, the breed­ing program at Namulonge, Uganda, has be­come the principal source of seed in the re­gion.

Table 2 presents information on the distri­bution of sweetpotato germplasm by CIP tonational programs in the region since 1993.The types (either clones or seeds) and num­bers of clones or families distributed to indi­vidual programs reflect the capacities andinterests of national programs, and the roleof those programs in the regional breedingstrategy.

The lead countries in the networks havetended to receive more clones and seed fami­lies for testing than others. Kenya, as the baseof the regional ClP breeder, is the primary sitefor the introduction and evaluation ofgermplasm, and so has received the most

(IP Program Report 1995-96 51

343

Argentino, Brazil, Colombia, Cuba,

orthAmllrico-IJSA,; Asia onld 01:eania--Austrolio,

apon, Korea, Myanmar, Papua New Guinea, Philippines, Sri lanka,

C; Alrica-Burundi, Cameroon, Egypt, Kenya, Madagascar, Rwanda, Uganda,

including CIp,lndcmesia,China, Uganda, and Rwanda,

Country Source 01 Igermpl gion" Total no. Seed

of clones familiesb

Latin North shipped

a A Africo

10 11 41

4 6 24

7 34

2 11

5 20

17 96 13

44 285 265

10 38 5

13 44

7 44 97

16 72

3 11

19 96 92

3 12 89

2137

75233 117

93

52 P,ogmml

Table 2. Distribution 01 sweetpotato germ plasm as clones or seed lamilies by CIP to countries in eastern, (entral,and southern Alrico lor evaluation and selection (January 1993 to February 1997). Number 01 clonesshipped is given by region 01 origin, and number 01 shipments to each country is given in parentheses.

clones and families. Kenya is also the princi­pal regional site for the redistribution of clonalgermplasm by CIP from the Plant QuarantineStation at Muguga.

The total number of clones and seeds in­troduced (as shown in Table 2) is not neces­sarily a true reflection ofthe number of geno­types that have made it to the field for test­ing. Losses frequently occur during the pro­cess of introduction and multiplication. Thatis particularly true for the introduction ofclones as in vitro plantlets. Since 1995, mostclonal germplasm distributed in the region byClP has been shipped in the form of cuttingstaken from pathogen-tested mother plants atthe Plant Quarantine Station at Muguga,Kenya. Losses during transport and establish­ment have decreased markedly as a result.

Summary Results

Following introduction and initial multiplica­tion in each country, trials are conducted toevaluate the performance of introduced geno­types and to select superior performers. Ini­tial results of evaluations of introducedgermplasm are beginning to appear in reportsof national programs and networks, withpromising performance reported for a num­ber of introduced clones. Here we will mainlyexamine summarized results from evaluationsof introduced clones and selections from seedfamilies at sites in Kenya over the past fewyears to illustrate some preliminary conclu­sions about the performance of introducedgermplasm in the region.

Clone performanceA total of 208 introduced clones were

evaluated at six sites covering a range ofKenyan sweetpotato production zones be­tween 1994 and 1996. Table 3 gives sum­mary results of the 22 highest yielding clones,along with information on the performanceof a few local checks and farmers' varieties.

The yield performance of clones in eachtrial was ranked by quartile, and for eachclone the number of trials in which the cloneperformed in the first, second, third, or fourthquartiles was counted (Table 3). This infor-

mation was used to derive a weighted meanof performance for each clone over all trialsin which it was evaluated. Mean root drymatter (OM) content for each clone from tri­als in which that was evaluated is also given.Clones were not always evaluated in the samenumber of trials at the same number of sites.Therefore, results do not necessarily indicatebroad adaptation over all sites, and the re­su Its for different clones may not be strictlycomparable, particularly when the numberof trials was low.

Clones from diverse sources had high,stable yields in Kenya. The large number ofclones from the International Institute ofTropi­cal Agriculture (IITA), selected throughmultilocational trials at humid and subhumidlowland sites in Nigeria, was noteworthy, thusindicating the value of multilocational selec­tion programs.

The root OM content of the stable, high­yielding introduced clones was usually be­low 30%, whereas that of the local checkvarieties was over 30%. But several intro­duced clones did have OM contents above27%, indicative of acceptable taste. Severalof the clones listed in Table 3 have been se­lected for further testing at sites in Kenya andhave been widely distributed to other coun­tries in the region for further testing. A num­ber of these clones, such as Naveto (440131)and Van Shu 1 (440024), are reported to beperforming well at various sites. Zapallo(420027), with relatively low OM, but highprovitamin A content, and an apparent ca­pacity to produce well under drought, hasalso been widely distributed for testing. SantoAmaro (400011) yielded in the top quarti Iein eight out of nine trials and will be widelydistributed.

In contrast to the performance of intro­duced clones at most sites in Kenya, virtuallyall exotic clones introduced and evaluated atthe Namulonge Agricultural and Animal Pro­duction Research Institute (NAARI) in Ugandahave succumbed to SPVO. This indicates thathigh levels of resistance to this disease arerare or absent in germplasm introduced fromoutside the region. In contrast, frequency of

ClP Progrom Report 1995-96 53

Seed family performanceThe performance of seed families intro­

duced from outside the region, or from seedcollected from introduced clones at Nairobi,Kenya, is reported in Table 4. The 31 clones

Table 3. Summary of yield performance and root dry matter wntent of the best performing introduced clones andlocol check varieties over trials in Kenya from 1994 to 1996 {out of 208 introduced}.

Total Weighted Root (n)

no. mean OMtrials £Ontent

4

9 1.89 39 2.11 28. 3

12 1.92 27.00 39 27.36 7

18 23.34 613 1.77 29.58 47 2.14 24.33 3

17 1.88 2 56 1.17 63 1.33 20.63 3

10 LBO 23.35 49 1.89 25.99 88 1.25 20.03 46 1.67 30.00 5

10 1.60 922 116 6

8 64 4

11 714 814 84 2

14

1111 9

1

2.54 26.25 4.18

resistance is high in local farmers' varietiesfrom Uganda and in clones bred by the breed­ing program at NAARI. Fortunately, siteswhere high levels of resistance to SPVD areessential are relatively few in this region.

54 Program 1

CIP Program Report 1995-96 55

lected from the same batches of introducedseed survived more than two seasons underthe high SPVO pressure in the field there.

The preponderance of clones with IITA par­entage among them indicates that widelyadapted progenitors tend to yield a high fre­quency of widely adapted selections. The lowOM content of almost all selected clones,however, indicates a need for using region­ally adapted parental clones, such asMugande, with a high OM content. In fact,the experience of the breeding program atNAARI, which emphasizes the use of Ugan­dan and regionally important clones as pro­genitors, shows a high frequency of clones

surviving from a 2-yr process of selection atKakamega were evaluated in a preliminaryyield trial with two replications. Clones de­rived from several hundred seedlings wereinitially evaluated for appearance, high yield,and resistance to SPVO (disease pressure ismoderately severe at Kakamega).

Mugande, a variety recently introduced toKenya from Rwanda, was included as acheck. Mugande was among the top yieldersand had high root OM content. Althoughmany of the experimental clones yielded well,root OM content was consistently low, thusindicating a low likelihood of taste accept­ability. At NAARI in Uganda, no clones se-

Table 4. Performance of top-yielding seedling-derived clones selected from introduced seed in a preliminary yieldtrial at Kakamega, Kenya, 1996, long rains.

reaching the advanced trial stage with theregionally important variety, Tanzania (SPN/0), as their female progenitor.

Conclusions and Future Focus

Results of evaluations of introduced, elitesweetpotato germplasm in eastern, central,and southern Africa are promising. Trials inKenya have identified several clones withhigh and stable yields over production envi­ronments with the range of regionally impor­tant production constraints. Also, in contrastto the majority of local varieties, which arewhite-fleshed, a number of introduced cloneshave orange flesh, due to a high content ofprovitamin A.

Introduced clones have demonstrated con­siderable potential for increasing sweetpotatoyields at several sites throughout the region,and are already being adopted by farmers inKenya and Zaire.

Local farmers' varieties have also shownconsiderable value, particularly with respectto root OM content, which is closely relatedto eating quality. A number of farmers' vari­eties, such as Mugande, have also demon­strated early, high, and stable yields. Severalpromising African farmers' varieties are al­ready on the CIP list of pathogen-testedclones. More clones are cleaned up for addi­tion to the Iist as they are identified.

In environments where SPVO pressure ishigh, as in the moist-warm sweetpotato pro­duction areas of southern Uganda, most in­troduced clones do not have the high levelsof resistance required to survive. Localgermplasm must serve as the principal sourceof resistance. The Ugandan breeding programat NAARI has recently made extensive use ofthis local germplasm in breeding new clonesthat are now reaching the final stages of se­lection.

Initial results of the evaluation and selec­tion of clones from introduced seed popula­tions at sites in Kenya and Uganda were notvery promising. The breeding focus has

56 Programl

sh ifted to the combination of exotic and lo­cal germplasm sources in the regional cross­ing block at NAARI. Testing and selection ofprogenies from this program are conductedat sites in major sweetpotato-producing zonescovering a range of regionally importantagroecological conditions in Uganda, Kenya,and Tanzania.

At this stage of sweetpotato improvementfor eastern, central, and southern Africa, eachof the three approaches outlinedabove--introduction of exotic clones, use oflocal farmers' varieties, and breeding of newvarieties-can make a contri bution tosweetpotato variety selection. With time, andthe success of current breeding efforts, we canexpect a shift to greater reliance on the prod­ucts of the regional breeding program.

The major objectives of our regional breed­ing effort are to select varieties with accept­able characteristics that are important nowor have potential importance in the region.These are:

• taste acceptability/dry matter;• high OM content and orange flesh (to com­

bat vitamin A deficiency);• suitability for improved farm-level process­

ing (high OM content, attractive appear­ance, and properties for commercial prod­ucts, particularly flour); and

• production of vines for animal feed.

Within the overall context of use objec­tives, secondary objectives will be fine-tunedas necessary on the basis of further testing inthe major production environments. Impor­tant areas of focus include assessing:

• earliness vs. in-ground storability;• drought tolerance--planting material per­

sistence, establ ishment, yield;• nutrient efficiency (P and K in southwest

Uganda); and• improved techniques for selection for

SPVO resistance.

Resu Its to date of regional sweetpotatobreeding efforts are encouraging. We are con-

fident that our breeding efforts and regionalapproach will do much to enhance the roleof sweetpotato as an important food security

crop in this region, and to help transform thecrop into an important income generator forthe region's farmers.

(IP Program Report 1995-96 57

c.c. Crissman1, J.M. Andez, and S.M. Capalboz

Tradeoffs in Agriculture, the Environment,and Farmer Health

Figure 1 depicts a model of land use andcrop management decision-making. The up­per part of the figure pertains to the analysisof a unit of land at the farm level. Prevailingprices, pol icies, technologies, and the physi­cal attributes of the unit of land affect the farm­ers' management decisions on land use andinput use. These decisions affect agriculturalproduction, but also may affect the environ­ment and human health through two distinctbut interrelated mechanisms. Farmers firstdetermine which units of agricultural land areput into production-the land use decision.Then, on the land in production, farmers makemanagement decisions that determine theapplication rates of chemicals, water use, andland management practices--the input usedecision. Physical relationships between theenvironmental attributes of the land in pro­duction and the management practices thenjointly determine the agricu Itural output, andhuman health and environmental effects as-

The method used here is to define a com­mon unit of measurement valid to the differ­ent disciplines and predict the effects of tech­nological or policy changes on those units.In this case, the unit is a farm field. By de­scribing the population of these units statisti­cally and estimating effects on each unit, it ispossible to aggregate those effects to a leveluseful for policy analysis. Using this informa­tion, one can defi ne aggregate tradeoffs be­tween economic and environmental or healthoutcomes in the form of a tradeoff curve.

search on pesticide effects is to improve thepotential for policy analysis with sustainableagriculture criteria by developing and imple­menting a framework that links macrotypepol icy to microtype effects.

An Integrated Agriculture/EnvironmentModel

1 ClP, Ecuador Liaison Office.2 Montana State University, Bozeman, Montana, USA.

58 Programl

Pol icy analysis is typically undertaken nation­ally or regionally. The analysis frequently usessecondary data that reflect aggregates. How­ever, policy analysis with sustainable agricul­tural development objectives must includeenvironmental effects that are location-spe­cific. Pol icy analysis in the heterogeneousbiophysical setting of the tropical mountainsof Ecuador suffers serious deficiencies fromthe averaging effects of using data that arenot location-linked. One objective of the re-

Over the pasttwo decades, sustainability hascome to mean for many the maintenance andimprovement in human living standards, stan­dards that are affected by changes in the en­vironment and in human health and eco­nomic status. Incorporating sustainability cri­teria into the mandate of CIP implies that theCenter should critically examine not only theproductivity but the potential environmentaland health effects of its research. In the het­erogeneous and frequently fragile environ­ments that are among the priority regions forClP, there are considerable tradeoffs betweenproductivity gains and their potential envi­ronmental and health effects. This paper re­ports on a general approach to measure theeconomic, environmental, and healthtradeoffs associated with agricultural tech­nologies and how those tradeoffs may be al­tered through technology or policy changes.The research reported here demonstrates thisapproach in a study of the environmental andhealth consequences of pesticide use in po­tato production in Ecuador.

....

Productiontechnology

Crop production

If crop production

(IP Progrom Report 1995-96 59

tinuously throughout the calendar year, datawere collected for parcels, where a parcel isdefined as a single crop cycle on a farmer'sfield. Detailed parcel-level data were collectedmonthly. Potato production in Ecuador is man­agement-intensive, and there are as many as20 distinct operations during the 6-month cropcycle.

Late blight caused by Phytophthorainfestans is the principal disease, alid the tu­ber-boring Andean weevil (Premnotrypesvorax) and several foliage-damaging insectsare the principal pests affecting production.

Management decisions tomaximize expected profit

Prices/policies

Land use/crop choice decisionto maximize economic returns

Location-specificenvironmental andhealth outcomes

If conserving use

Biological/physicalparameters

.. .

Figure 1. An economic model of land use and crop management decision-making.

sociated with the particular unit of land in pro­duction. Thus, the land use and input use de­cisions of farmers form the linkage betweenpolicy and technology and the environmentaland health consequences.

The case studyThe case study was conducted in a 70-km 2

watershed in the principal potato-producingzone of Ecuador. Production data were col­lected in a farm-level survey on 40 farms. Be­cause crops are planted and harvested con-

The Pesticides Effect Study

They are controlled with dithiocarbamate fun­gicides and neurotoxin insecticides from theorganophosphate and carbamate families.

The case study focused on groundwatercontamination through leaching and the oc­cupational health issue of the pesticideapplier's exposure as the expressions of en­vironmental and health consequences of pes­ticide use.

The simulation modelThe decision-making model of Figure 1 is

embedded into a simulation model (Figure 2)for empirical application. The simulationmodel is based on econometric revenue andproduction models, a soil pesticide leachingmodel, and a health effects model. Figure 2illustrates the flow of the economics, pesti­cide leaching, and health portions of the simu­lation model. A policy or technology scenariois imposed on the economic model where theunit of analysis is a parcel of land. The eco­nomics portion consists of four components.First, the model is initiated by sampling theeconomic and physical characteristics of thefields in the study watershed. Second, weobtain net returns distributions of the princi­pal crops in the rotation (potatoes and pas­ture for milk production), which determinethe land use decision. In the third component,a potato production model produces esti­mates of the quantity and frequency of pesti­cides used. The fourth component is a re­stricted revenue function used to predict thevalue of production. As shown in Figure 2,the economic model generates three types ofoutputs that are used in the subsequent por­tions of the simulation model.

The leaching model is a detailed processmodel that uses soi Is and other physical datafrom the watershed, the chemical character­istics of the pesticides, the pesticide appl ica­tions from the economics portion of the

model, and more than two decades of dailyrainfall, temperature, and evapotranspirationdata from weather stations in the area. Theleaching model predicts the downward move­ment of pesticide active ingredients throughthe different soil horizons.

60 Program 1

The health component of the simulationmodel consists of an estimated health pro­duction function that specifies health as afunction of the total number of pesticide ap­pi ications, total quantity of appl ied neurotoxicsubstances to which an individual was ex­posed, and other factors. We measure healthas an individual's mean neurobehavioralscore, an index constructed from a series ofneurobehavioral tests. Neurobehavioral testsmeasure specific aspects of cognitive func­tion such as attention span, visuospatialmemory, and reaction time, which are impor­tant for decision-making and daily perfor­mance of farm work. We also measured poi­soning rates to establish the size of the prob­lem.

Because we use mutually compatible datasets, the three separate disciplinary modelsproduce results that are linked. As the last boxin the figure shows, we use the linked resultsto compare the tradeoffs in gains and lossesamong farm revenues, water table contami­nation, and appl icator health.

Note that the model is stochastic. At sev­eral points, the model samples distributionsthat are derived from physical and economicdata. Thus, any two runs of the model are notexpected to produce precisely the same re­sults. This is advantageous in two ways. First,since economic and physical processes arestochastic, the model can produce all out­comes in addition to the expected averageoutcomes. Second, by using distributions con­structed from the sample data, you can ap­peal to rules of aggregation to obtain sum­mary statistics for the group. Reasonable as­sumptions about the structure of productionpermit statistically valid extrapolation beyondthe data collection site, an important impli­cation for policy analysis.

Presentation of Results

Use of tradeoff curvesTo facilitate interpretation of the model

resu Its, the tradeoffs between agricu Iture,health, and the environment are presented ina series of pairwise comparisons. The hypo-

Average health riskestimates

I Health model I

Pesticide applicationnumbers and quantities

by field

/

CIP Progrom Report 1995-96 61

Construction of an empiricaltradeoff curveAn empirical curve is constructed by im­

posing different policy scenarios on themodel. Figure 4 is a scatter diagram of thecomparison that relates the level of fungicideleaching with the value of agricultural pro­duction. The squares are the base case pro­duced with simulations using the actual data

ferent technologies may be more or less dam­aging at different levels of output.

,

Value of agriculturaloutput by crop

Aggregate value ofoutput, costs and netreturns produced in

watershed

I Economic model I(see Figure 1)

Economic-environment-healthtradeoffs

Daily pesticideapplications by site

ILeaching model I

Loadings andconcentrations leached and

environmental risk bychemical type in watershed

thetical tradeoff curves in Figure 3 illustratethe tradeoffs between agricultural output andenvironmental effect. The tradeoff curve rep­resents all the possible pairs of outcomes fora given technology. Thus, different curves areavailable for different technologies. The movefrom T, to T2 shows a change in technologythat everywhere maintains output while re­ducing environmental effect. The slope of thetradeoff curve provides information about theopportunity cost of environmental quality interms of lost output. As curve T

3shows, dif-

Figure 2. An integrated simulation model for tradeoff analysis.

Policy and technology scenarios

Environmental effect

T,

crete expression of what is usually a mentalcalculation. In the example, the politician oranalyst can readi Iy see what the sacrifice of asingle unit of environmental quality will gainin units of agricultural production. Whetherthe size of the sacrifice is acceptable becomesa political decision.

Case study resultsFirst, because of the short half Iife of the

pesticides in use, the fixation of these pesti­cides to the organic matter in the soil, andthe frequent but light rainfall that moves thepesticides slowly downward, water contami­nation from pesticide leaching is not signifi­cant. At four parts per bill ion, carbofuran con­tamination of the water table is a full magni­tude below the USEPA tolerance limit of 40ppb. Second, at 171 per hundred thousandinhabitants, the rate of work-related pesticidepoisonings ranks among the highest recordedin the world. Third, the health effects ofchronic exposure severely depress theneurobehavioral performance of a large seg­ment of the applicators and farm families.Fourth, our economic efficiency analysisshows that farmers are not overspending andapplying pesticides irrationally.

These results run counter to publ ic percep­tions in Ecuador. Farmers are thought to make

The reduced value of potato productioncomes from two sources. First, farmers leavemore area in pasture, which produces lessrevenue than potatoes; second, they use lessfungicide on potatoes, which reduces yields.The figure also depicts increases in potatoprices. Higher prices increase profitability,thus causing farmers to plant more area topotato and to use more fungicides. That inturn increases fungicide leaching and thevalue of production.

set. Each square represents the average out­come of 30 fields each with 5 productioncycles. This is repeated 30 times. Changingrelative prices causes movement along acurve. For example, when the levels of fun­gicide tax are imposed on the model, there isa reduction in fungicide use with a conse­quent reduction in fungicide leaching and thevalue of agricultural production.

Mean crop output

Figure 3. Output-environment tradeoffs associated with alternative technologies.

Implications for Policy/TechnologyAnalysis

Several issues relevant to policy analysis canbe addressed by tradeoff curves. Pol iticiansimplicitly use tradeoff curves every day. Bythe nature of their jobs, they are concernedwith winners and losers resulting from policydecisions. The tradeoff curve is simply a con-

62 Progmm 1

120011001000

+ 60% pesticide tax

tJ. 60% potato subsidy

Heterogeneity of environmentPolicy analysis that incorporates environ­

mental effects must also consider the variabi 1­ity of the impact of the policy itself. The re­search watershed was classified into fourmicroregions (Figure 5) where we plot linesthrough the scatter plots to simplify their in­terpretation. Three of the microregions havesimilar low-leaching characteristics; thefourth zone is much more susceptible toleaching. There is considerable heterogene­ity present even in small areas. We can dif­ferentiate such phenomena by linking envi­ronmental data to economic data. With suchdifferentiation, regu lations to improve theenvironment could be based on agriculturalzoning rather than on taxes or broad-basedprohibitions on pesticides that uniformly af­fect all production zones.

ClP Program Report 1995-96 63

030% pesticide tax

~ 30% potato subsidy

~O 000 roo 000 000

Val ue of output (1000 sucres)

400300

II Sase*90% pesticide tax

+90% potato subsidy

O-l----rq·~

200

0.5-1------.-

1.5 -I------------....:E'-----@l)-ir-....-"...--<0>--..-----I

3-1--------------4'----------------1

Fungicide (kg)

4..-----------------------------,

2-1--------------t.:Ji'''1!l!lIs----<\!T----------OIl\!T-----I

2.5-1------------------------------1

•3.5+------------------------=------;

The worker-safety lobby in Ecuador is notnearly as well organized as the environmen­tal lobby, so there is little public discussionabout occupational health issues. With pes­ticide use an essential part of efficient potatoproduction, the policy debate should be cen­tered primarily on the safety of the pesticideapplicator and farm families and integratedpest management (IPM) techniques.

irrational, excessive use of pesticides withresulting widespread environmental contami­nation. Environmental lobbyists put forwardproposals to ban certain classes of pesticides,including carbofuran, based on the presump­tion of environmental contamination. How­ever, the research shows that a ban oncarbofuran would reduce potato production,but would only minimally improve the envi­ronment.

Figure 4. Pesticide leaching-output tradeoffs for base technology.

Zone4

3

14001300120011001000900

Although the conceptual model is appliedin an economics, pesticide leaching, andhealth study of pesticide effects, the model isflexible and can be applied to other researchquestions such as fertilizer use, erosion, oroutput price adjustments. Since the model isstatistically based, it can use data sets gener­ated from various sources.

The research reported in this paper devel­oped a conceptual model that provides link­ages between macropolicy and microtypeeffects. The linkage is provided by includinga farmer decision-making model. That modelshows how farmers react to policy or tech­nology changes through adjustments to landuse and input use decisions. The simulationmodel produces resu Its that can be aggre­gated for extrapolation beyond the actual casestudy area, thus making the model useful forpolicy analysis. Tradeoff curves are intro­duced as an analytical tool for summarizinglarge amounts of data and for illustrating themultiple effects of a given technology.

A weak link in most systems modeling workis the lack of economic criteria in the models.

800700600500400

b&//

~:=::::::::::::::::::::=::::::::::ne2Zone1All zones

300

o

0.5

-0.5 +----l---!----f----II-----I----f---I-----I----+---i----+---1200

Zone 3 '.

2

2.5

3.5

1.5

4

Technology effect analysisThe current technology to control the

Andean weevil relies on applications ofcarbofuran. CIP entomologists have devel­oped a set of IPM technologies that reducethe reliance on carbofuran. Here we simu­late the effect on health risk of an 80% adop­tion of IPM practices that reduce carbofuranuse by 40%, combined with a worker educa­tion program for safe handling practices (Fig­ure 6). Health risk is the percent chance of aone standard deviation decrease inneurobehavioral score below the mean scoreof the nonfarming urban control population.The analysis suggests that the combinationof IPM and improved safety practices couldreduce health risk by 50% or more.

Carbofuran (kg)

4.5-r--------------------------------....,

Including sustainability criteria into policydecisions in both developed and developingcountries has spurred substantial changes inthe mandates of agricultural research institu­tions and the manner in which research isconducted. One outcome of these changes isan increased emphasis on systems modeling.

Value of output (1000 sucres)

Conclusions

Figure 5. Carbofuran leaching-autput tradeoffs.

64 Progroml

0.5

12001100

IPM + low improvedsafety

IPM technology

Low improved safety

High improved safety

IPM + high improvedsafety

1000900800

(IP Program Report 1995-96 65

Implications of an Andean study. In:M.E. Bredahl, N. Ballenger, j. Dunmore,and T.L. Roe (eds.). Agriculture, trade,and the environment: Discoveringand measuring the critical linkages.Boulder, Col.: Westview Press.p. 173-197.

Crissman, c.c., D.C. Cole, and F. Carpio.1994. Pesticide use and farm workerhealth in Ecuadorian potato production.Am. j. Agric. Econ. 76(3):593-597.

700600500400300

0.3

0.2

0.1 -1-----1-----+---+----1----+---_---1-----1-----11-----1200

Base technology

0.4

O.6-r----------------- ---.

Value of output (1000 sucres)

Index of health risk

Figure 6. Health-output tradeoffs for carbofuran IPM and improved safety practices.

Selected Reading

Antle, j.M., S.M. Capalbo, and c.c.Crissman. 1994. Econometric productionmodels with endogenous input timing:An application to Ecuadorian potatoproduction. j. Agric. Res. Econ.19(1):1-18.

Antle, j.M., c.c. Crissman, R.j. Wagenet,and j.L. Hutson. 1996. Empirical founda­tions for environment-trade linkages:

Previous Page BlaDl~

Germplasm Management andEnhancement

[IP PlOglOm Report 1995-96 67

Pro

Program 2 works closely with CIP's fiveother programs, whose breeding activitiesused genetic resources from Program 2 to de­velop advanced clones. Program 2 was alsoan active partner in the CGIAR's SystemwideGenetic Resources Program and in globalapproaches. It has contributed to an interna­tional effort to develop plans that will inte­grate in situ and ex situ conservation of plantgenetic resources, in accordance with theConvention on Biological Diversity.

The future emphasis of Program 2 will beon determining the true biodiversity of C1P'smandate crops and their wild relatives, byclassical and modern methods, to more ef­fectively and efficiently conserve the maxi­mum diversity in each collection and in des­ignated core subsets.

REPORTPROGRAM

Ali Golmirzaie1

Genetic resources worldwide are being evalu­ated to preserve and improve them for futuregenerations. Program 2 has played an impor­tant role in the conservation of CIP's man­date crops (potato, sweetpotato, and Andeanroot and tuber crops-ARTC). During 1995­96, we worked to conserve, characterize, andevaluate these crops, using conventional andnonconventional approaches. We used theseapproaches in-house or in collaboration withresearch institutes in developed and devel­oping countries. The Program focused on: (1)increasing seed of wild potato andsweetpotato species; (2) identifying duplicatesand determining genetic diversity of potato,sweetpotato, and ARTC collections; (3) de­veloping and applying a cryopreservationmethod for potato; and (4) selecting a corecollection for potato and sweetpotato.

1 Program Leader, CIP, Lima, Peru.

Potato

CIP continued the process of selecting a corepotato collection. The largest number of po­tato cultivars in the collection correspondsto the tetraploid Solanum tuberosum subsp.andigena. Therefore, a core subset compris­ing 534 of the most diverse andigena culti­vars has been selected from 2,644 cultivarsof this species in the collection. We selectedcultivars in the core subset on the basis oftheir geographic origin, morphological char­acterization, and isozyme diversity for 9 loci.

The S. phureja collection at ClP contains170 accessions collected from the warmAndean valleys on the eastern side of theAndes of Venezuela, Colombia, Ecuador,Peru, and Bolivia. We performed a geneticdiversity analysis in this collection using therandomly amplified polymorphic DNA(RAPD) technique adapted for low cost andhigh throughputs.

We conducted cluster analysis on 131genotypes at 93 RAPD marker loci, which ledus to two conclusions: no geographic clus­tering exists and this material appears to be asingle homogeneous population. In the pro­cess of selecting a core collection, we com­pared two sampling methods: a marker-as­sisted sampling that takes the marker-basedclusters as "stratas" and systematically selectsaccessions from each stratum to maximize thegenetic distances in the samples, and the ran­dom sampling. Our analysis showed thatmarker-assisted sampling gave higher mo­lecular variance values (i.e., genetic diversity)than the random sampling. We found that asfew as 16 genotypes could constitute the S.phureja core collection.

ClP has also increased the in vitro potatocollection with the addition of 1,605 clonesfrom breeding programs at CIP. These clonesinclude ones with resistance to late blight,viruses, nematodes, insects, or bacterial wilt.In addition, we have precleaned 1,588Andean potato cultivars using in vitro ther­motherapy followed by meristem culture. Se­rological testing confirmed that the cultivars

68 Progrom1

are free of the six most important potato vi­ruses.

At CIP we preserve shoot tips in liquid Nat -196°C using a cryopreservation by vitrifi­cation method developed at Cornell Univer­sity, USA. Since adopting this method, ClPhas put 183 potato accessions in liquid N,with a high percentage of recovery (70%). Forrecalcitrant accessions that do not respondto this method, we modified the protocol andhave obtained 75% recovery after conserva­tion. Currently, 143 accessions are beingmaintained by cryopreservation.

We have continued to emphasize seed in­crease of the wi Id potato collection. The seedlots of many accessions are more than 25years old; either few seeds are in stock or theirviability is low. About 300 accessions havebeen rejuvenated at three sites in Peru(Huancayo, Cusco, and Cajamarca) by sibcrosses with manual pollination. About 63%of the collection has fresh seeds.

ClP has moved rapidly to meet the goalsof the Systemwide Information Network forGenetic Resources (SINGER). In April 1996,CIP became the first center to replicate its dataat the 51 NGER Network Operations Center atCGNET in Palo Alto, California, USA. In May1996, ClP staff helped conduct a workshopin Nairobi, Kenya, to train staff from other cen­ters in new information systems technologyfor the 51 NGER computer systems. Participat­ing centers were ICARDA, ICRAF, IITA,INIBAP, ILRI, and WARDA.

ClP's accession, cooperator, transfer, andcharacterization data for about 13,000 acces­sions of potato, sweetpotato, and otherAndean root and tuber crops are now on-linefor access by the world's scientific commu­nity on the Internet.

Sweetpotato

Polymerase chain reaction-based fingerprint­ing is routinely used for identifying duplicatesto reduce redundancy in our sweetpotato(Ipomoea batatas) germplasm. This is the first

step in constructing a sweetpotato core col­lection. Duplicate identification within Pe­ruvian sweetpotato accessions has so far re­duced the number of clones maintained inthe field gene bank from 1,939 to 909.

We compared the methods of duplicateidentification based on morphological char­acterization and DNA fingerprinting. Resultsso far show that when the duplicate groupscomprise morphologically identical acces­sions, no differences are found in their DNAfingerprints.

The second step for core collection con­struction is to assess genetic diversity. A setof sweetpotato cu Itivars from Papua NewGuinea, considered to be a secondary centerof sweetpotato diversity, was compared witha set of sweetpotatoes from South America.Based on the DNA fingerprint information,we calculated the genetic distance betweenthe two groups of cultivars. This study sug­gested that the PNG cultivars can be dis­tinguished from the South American cultivars.The average genetic distance between SouthAmerican cultivars is significantly greater thanthat in Papua New Guinea. This could indi­cate that the Asian cultivars are a subsetsample of South American cultivars. Thesestudies are continuing using larger samplesof sweetpotatoes from Asia and SouthAmerica.

CIP has increased the sweetpotato patho­gen-tested Iist with 20 other cu Itivars cleanedof viruses during 1995 and 1996. In addition,a new conservation medium that extends theperiod between subcultures to 1 year in thein vitro sweetpotato collection has been testedin 500 different cultivars. Survivability was100% in the new medium.

From 359 sweetpotato cultivars in thepathogen-tested list, 60 have been selectedas early maturing. A 7x7 lattice experimentwith 48 cultivars, using cv. Jewel as a con­trol, showed 21 cultivars with yields between19 and 30 t/ha 90 d after planting (DAP). Jewelproduced 17 t/ha. Twenty-nine cultivars had

yields ranging from 33 to 53 t/ha 120 DAP.Jewel yielded 33 t/ha.

CIP has improved techniques to increasethe seed stocks of wild Ipomoea species andincreased seed set considerably. The Centerhas produced more than 500,000 seeds from90 accessions of 7 wild species related to thesweetpotato, and almost 600,000 seeds from122 accessions of 32 other Ipomoea species.During the process of seed increase of Ipo­moea wild species classified outside SeriesBatatas, we found self-pollination in 22 spe­cies.

Germplasm enhancement through con­ventional breeding is an important activity.Wide genetic diversity collected at C1P is be­ing assembled through this breeding scheme.First, we randomly mated a large number ofclones in nurseries. Recurrent selection tocombine high dry matter content with otherdesirable traits has been practiced for threegenerations. After progeny testing, the prom­ising progenitors with diverse genetic back­ground will be identified and made availableto NARS and regional programs. This is anefficient way to speed up germplasm diffu­sion.

Andean Root and Tuber Crops

C1P is maintaining a collection of 1,266 ac­cessions of Andean root and tuber crops(ARTC) (oca, 482; ulluco, 446; mashua, 92;arracacha, 91; achira, 65; yac6n, 44; maca,33; mauka, 5; Pachyrhizus, 8; and 90 of theirwild allies) to protect them from genetic ero­sion. So far, of 506 accessions we have iden­tified 146 morphotypes of oca, 92 of ulluco,51 of mashua, and 31 of arracacha.

Additional investigations on the samearracacha material through RAPD resulted inthe identification of 32 arracacha genotypes,suggesting an almost perfect congruence be­tween morphological and molecular charac­terization. Thus, our results on arracacha in­dicate that 51 % of the Peruvian arracachasmaintained by CIP are probably duplicates,

CIP Program Report 1995-96 69

and should thus undergo conservation bymeans of seeds.

The ex situ conservation of ARTC iscomplemented by activities to study the insitu management of these crops in 21microcenters of diversity (14 in Peru and 7 inBolivia). Factors that contribute to the increaseor loss of genetic diversity of these crops arebeing studied as well as the main constraintsto expanding use of these crops.

70 Program 2

Descriptor lists for oca, ulluco, andarracacha are in the final stage of develop­ment in close cooperation with AndeanNARS. They will be published in 1998. De­scriptors for mashua, yac6n, and achira arealso being tested. Andean germplasm banksmaintain about 9,800 ARTC accessions. Thedevelopment of descriptor lists for ARTC willhelp to identify duplicates and optimize theirex situ conservation.

Advances in Potato Cryopreservationby Vitrification

A.M. Golmirzaie and A. Panta1

One way to safeguard plant genetic resourcesagainst erosion is to use cryopreservation--storing plant material at ultralow tempera­ture (-196°C) in liquid nitrogen (N).

Cryopreservation has been applied to morethan 80 plant species and is considered a safeand less labor-consuming conservationmethod than in vitro maintenance. Storedmaterial can be conserved indefinitely with­out genetic erosion. Because all chemicalreactions cease in liquid N, no cell divisionoccu rs and cell degeneration or geneticchanges cannot take place.

Potato cryopreservation work began in1977. It has been carried out with excisedmeristems, pollen, shoot tips, cell cultures,and protoplast-derived cell colonies. Entireplants capable of undergoing normaltuberization have been obtained from cul­tures cryopreserved for 4 yr. These findingsjustify the application of cryopreservation tothe long-term conservation of potato.

The in vitro Potato Base Collection (PBC)held at ClP contains more than 6,000 acces­sions and is increasing rapidly with new, im­proved material developed by geneticists. Toreduce the cost and labor involved in main­tenance, in 1995, in a United Nations De­velopment Program collaborative project withCornell University, CIP started testingcryopreservation by vitrification, a methoddeveloped by P. Steponkus. With this method,shoot tips (the meristem dome with severalleaf primordia) are dehydrated by exposureto concentrated solutions of sugars andcryoprotectants, and are then frozen rapidly,thus preventing intracellular ice formation.

1 CIP, lima, Peru.

The use of shoot tips has an advantage overother tissues because they can be regener­ated into plants that are more faithfully iden­tical to mother plants.

This article describes attempts tocryopreserve 183 potato genotypes and toassess the feasibility of this approach for stor­ing the PBC.

The Cryopreservation Technique

In vitro growth of mother plantsThe following genotypes to be

cryopreserved were taken from the PBC:Solanum tuberosum subsp. andigena (61 ), S.chaucha (1), S. phureja (38), S. stenotomum(57), S. goniocalyx (9), natural hybrids of S.goniocalyx x S. stenotomum (10), and S.stenotomum x S. goniocalyx (4), plus 3 otheraccessions whose species determination isunder way. This material is now being con­served in in vitro long-term storage by slowgrowth at low temperature in a medium con­taining sorbitol as an osmotic growth retar­dant. Plants from long-term storage weremicropropagated by single-node stem seg­ments in tubes containing an MSA medium(Murashige-Skoog salts, 0.4 mglL thiamin, 2mg/L glycine, 0.5 mglL nicotinic acid, 0.5mglL pyridoxine, 0.1 mglL gibberellic acid,2.5% sucrose, and 4 giL SIGMA phytagel).

Improving in vitro growth ofmother plantsWe did this work with recalcitrant

accessions--those that after being frozen twoor three times did not survive. Plants comingfrom long-term storage were subcultured twoor three times in magenta jars containingsemisolid MSA propagation media and cov­ered with a transparent polypropylene film

(IP Progrom Report 1995-96 71

with a filter (SIGMA, C6920) to increase ex­change of air. The phytagel, the gelling agentof the MSA medium, was replaced by agar.The medium was poured into magenta jarsin two layers: first a semisolid MSA medium(15 ml) containing agar, and then liquid MSAmedium (10 mil. Plants were propagated byplacing 9 single nodes on the medium in eachjar. Several subcultures were required to in­crease the vigor of weak genotypes.

Cryopreservation by vitrificationThe vitrification method, based on

Steponkus's method, involves removing axil­lary shoot tips (1.5 mm long) from plantletsgrown in vitro for 30-45 d. The shoot tipsconsist of 4-5 leaf primordia and the apicaldome.

They are first precultured in a modifiedMurashige-Skoog medium (supplementedwith 0.04 mglL kinetin, 0.5 mg/L indoleace­tic acid, and 0.2 mglL gibberellic acid) con­taining 0.09 M sucrose for 24 h under properincubation conditions for micropropagation.Nextthey are incubated in the same mediumcontaining 0.06 M sucrose for 5 h at roomtemperature. The shoot tips are dehydratedby placing them in a vitrification solutioncontaining ethylene glycol:sorbitol:bovineserum albumin (50:15:6 wt%) for 50 min atroom temperature.

The shoot tips are then transferred to 0.25­ml propylene straws with 150 1-11 of vitrifica­tion solution, and the straws are rapidlyquenched in liquid N. Following storage inliquid N, the shoot tips are thawed, expelledfrom the straws into a hypertonic (1.5 osmo­lal) sorbitol solution at room temperature, andincubated for 30 min.

The shoot tips are then plated on a semi­solid potato meristem medium containingMurashige-Skoog salts supplemented with0.04 mglL kinetin, 0.1 mglL gibberellic acid,and 25 giL sucrose, and maintained undernormal incubation conditions formicropropagation. After 4-6 wk, survival wasevaluated by counting plantlets growing fromshoot tips.

72 Program 2

With this procedure, all183 selected geno­types were frozen and stored in liquid N. Foreach genotype 120 shoot tips were stored(Figure 1), and for dehydration control 20shoot tips were loaded into straws (2 repeti­tions of 10 samples), where they continuedto thaw without freezing.

One day after freezing, 2 straws contain­ing 10 shoot tips each were removed fromthe liquid N and the shoot tips were thawed.Survival was evaluated 6 wk after thawing(Figure 2). For accessions that did not respondeven when evaluated three times, the storedshoot tips were discarded and the assay wasrepeated once or twice more, using dehydra­tion times of 45, 55, and 60 min.

post-thaw recoverySurvival of 80 genotypes was evaluated by

thawing 2 repetitions of 10 shoot tips of eachgenotype 3 mo after freezing. Shoot tips werethawed at room temperature and transferredto a recovery medium. After 6 wk, survival

Figure 1. Tank used at (IP for storage of cryo­preserved potatoes. Tank capacity is4,800 cryovials of2 ml.

Liq Nit: 1 day

(IP Program Report 1995-96 73

We obtained 10 more surviving accessionsby making these modifications. Table 1 shows

Post-thaw recoveryWith thawing after 1 d of freezing, 69% of

the genotypes tested were successfully recov­ered. Different survival levels were observed,wh ich cou Id be related to the vigor of motherplants or genotype dependence (Figure 3).With shoot tips isolated from more vigorousmother plants and with minor changes in de­hydration time, the percentage of survivinggenotypes increased to 75%. This increaseresulted from changes in dehydration times(45, 55, and 60 min) for the recalcitrant ac­cessions.

be due to the sorbitol content in the mediumused for long-term storage, which could haveaffected the plants' hormone balance. Thisassumption needs more research to be con­firmed. After culturing these genotypes inmagenta jars, using at least 3 subcultures,plants were more vigorous, stems were stron­ger, leaves were bigger, and the lack of api­cal dominance was disappearing.

CIP 703969

___c_o_n_t~ro_I__11 Dehydration: 50°

Results

Figure 2. Plantlets of S. tuberosum subsp. andigena genotype after 6 wk of plating. left: plate showing 70%survival from dehydrated shoot tips and shoot tips not frozen. Right: plate showing 60% survival afterpost-thaw of shoot tips.

In vitro growth of mother plantsSome genotypes that were propagated in

tubes containing a semisolid MSA mediumshowed symptoms of weakness, especiallythose that showed 0-20% survival after vitri­fication. They grew slowly, plantlets werethin, and leaves were small. Some showed aloss of apical dominance after 3 wk of propa­gation. The lack of vigor of these plants could

Cryopreserving apical shoot tips fromvigorous in vitro plantsSeven genotypes chosen randomly were

micropropagated by several subcultures ofapical tips in magenta jars. The growth timebetween subcultures was 3 wk. After 7 sub­cultures, 140 apical shoot tips from vigorousplants of each genotype were isolated. Theywere processed by the vitrification methodusing 50 min of dehydration.

was evaluated by counting the number of re­growth plantlets. The plantlets were thentransferred to an MSA medium.

29

47

Average

survival

rate (%)

CI testing 50 min ofdehydration time

• testing 45-60 min ofdehydration andmore vigorous plants

75

7S

genotypes

4

subsp. andigena and S. goniocalyxgenotypes.The highest (47%) belonged to the naturalhybrid S. goniocalyx x S. stenotomum. Moreresearch is needed to confirm whether this

PI

10 20 30 40 50 60 70 80 90 100

•II II 11 I. rI ....

I I I I I I I I I Io

5

Survival levels (%)

10

20

25

15

30

Total genotypes (%)

35

74 Progrom2

Figure 3. Survival percentage of potato shoot tips of 183 genotypes comparing the vitrification methad using 50min of dehydration vs. testing other periods of dehydration (45,55, and 60 min) and more vigorousplants, Clp, 1995-96.

survival expressed by species or genotypegroup. The percentage of surviving genotypesvaries from 72 to 80. The lowest average sur­vival rate (29%) was found in S. tuberosum

Table 1. Survival percentage of 183 genotypes and recovery rate af each species ar group after cryopreservationby the vitrification method, Clp, 1995-96.

55

o

50

33

Conclusions

(IP Progrom Report 1995-96 75

The success obtained in this work shows thefeasibility of applying cryopreservation tech­niques to the long-term storage of a widerange of potato genotypes. In this work, sur­vival was evaluated strictly by the number ofregrowth shoot tips; in other works, recoveryhas been evaluated by including leaf expan­sion without regrowth.

We also demonstrated that survival ratecan be dramatically increased by improvingthe pregrowth conditions of plant material andby using apical shoot tips. Studies on the in­fluence of different phenotypic and physi­ological characters of plants on the freezingprocess would help enhance their viability.

CIP is now cryopreserving 145 potato ac­cessions and trying to recover 100% of thegenotypes to be cryopreserved. To reach thisgoal, we are improving the vitrificationmethod and testing other methods, such asdehydration and encapsulation, and dropletmethods that have been tested by other re­searchers with a wide range of crops.

703859700874703579

variation is due to differences between spe­cies.

We evaluated 80 genotypes for survival 3mo after freezing. In the first evaluation (1 dafter freezing), the average survival was 46%;after 3 mo it was 40%. This difference wasnot statistically significant. Theoretically, thesurvival rate shou Id not change even if theplant material were stored for many years. Toconfirm this hypothesis, we plan a third evalu­ation after 1 year of freezing.

Table 2. Survival percentage af seven potato genotypes after cryopreservation by the vitrification method,comparing the use of axillary shoot tips with apical shoot tips from vigorous plants, Clp, 1995-96.

Cryopreserving apical shoot tips fromvigorous in vitro plantsAfter we froze about 100 accessions, it be­

came evident that plant vigor is a bottleneckin the cryopreservation process, and that thesurvival rate obtained by using axillary shoottips varies by genotype. With apical shoot tipsfrom vigorous plants, seven genotypes testedshowed higher survival percentages (Table 2).The survival of two recalcitrant genotypes wasover 50%, and the average survival rate in­creased from 31 % to 67%. We planted fiveplants recovered from each genotype toevaluate phenotypic characters under green­house conditions.

We expect to be able to safely store thePotato Base Collection (approx. 4,000 acces­sions) using cryopreservation. Since thisgermplasm will eventually form a foundationfor potato breeding work for future genera­tions, we plan to emphasize genetic stabilitystudies.

Selected Reading

Bajaj, Y.P.S. 1987. Cryopreservation ofpotato germplasm. In: Bajaj, Y.P.S. (ed.).

76 Program 2

Biotechnology in agriculture andforestry. Vol.3: Potato. Springier-Verlag,Berlin. p. 472-486.

Benson, LE., M. Wilkinson, A. Todd, U.Ekuere, and j. Lyon. 1996. Developmen­tal competence and ploidy stability inplants regenerated from cryopreservedpotato shoot-tips. Cryo-Letters 17:119-128.

Steponkus, P.L., R. Langis, and S. Fujikawa.1992. Cryopreservation of plant tissuesby vitrification. Adv. Low-Temp. BioI.1:1-16.

M. Ghislain, D. Zhang, D. Fajardo, Z. Huaman, and R. Hijmans l

Genetic Diversity Analysis in a CultivatedAndean Potato, S. phureja JUZ. et Buk.

We used a total of 163 accessions, presum­ably belonging to S. phureja, for this research.We took leaf samples from in vitro-grownplants and from greenhouse collections. We

Materials and Methods

The 5. phureja collection maintained at ClPcontains 170 accessions collected from thewarm Andean valleys on the eastern side ofthe Andes of Venezuela, Colombia, Ecuador,Peru, and Bolivia at an altitude of 2,000-3,700m. It has been assembled through severalcollecting expeditions and germplasm dona­tions. Within this collection are 25 accessionsthat were labeled as 5. phureja but whosemorphological characters suggest that theyare closer to S. tuberosum subsp. andigena.

(IP Program Report 1995-96 77

The work reported here is the first reporton the use of molecular markers to fingerprintan entire cultivated potato collection. Weshow an assessment of the genetic diversityrevealed by molecular data, and identify agenetically representative, marker-assistedsample of this potato collection.

Because of the small size of the collectionand its importance in potato breeding, wechose S. phureja as a model collection to testhow molecular marker data can provide ad­ditional information to improve germplasmmanagement. Here we present our work ofgenetic diversity analysis in S. phureja usingthe randomly amplified polymorphic deox­yribonucleic acid (DNA) (RAPD) techniqueadapted for low cost and high amount ofsamples processed. The results not only ledto an increase in our understanding of thegenetic diversity in 5. phureja, but are rel­evant to the construction of core collectionsin other cultivated potato species as well.

The gene bank held at CIP maintains 3,527accessions of cultivated potatoes (Solanumspp.) collected from throughout the Andes.This potato collection provides a long-termsafeguard for the otherwise rapidly depletinggenetic diversity in this crop and related spe­cies. The large size of this collection, togetherwith limited funding, restricted the charac­terization and evaluation of these materialsand hindered their use for breeding.

An increasingly popular solution is to con­struct a small core collection from a largecollection. An ideal core collection shouldrepresent the greatest part of genetic diver­sity in the large collection. Information pro­vided by molecular genetic variation is use­ful in creating such smaller, but geneticallyrepresentative, core collections. First, molecu­lar marker data can be used to reduce theredundancy in the collection. Second, thelarge collection can be rationally stratifiedinto small groups based on molecular varia­tion, so that samples can be taken from eachstratified group to form a core. Third, themarker data can be used to assess geneticdiversity in a collection composed of preex­isting groups formed on the basis of other cri­teria (e.g., ecogeographic data).

Solanum phureja is a diploid cultivated po­tato. It is important in potato breeding becausemany accessions of this species have valu­able resistance to several important biotic andabiotic stresses (e.g., late bl ight (LB), bacte­rial wilt (BW), and nematodes) and producetubers that have good culinary properties. Theprecise site of origin of 5. phureja is unknown.Today, the species is distributed in a long,narrow strip along the eastern slope of theAndes from Colombia to Bolivia (Figure 1).

1 CIP, Lima, Peru.

Figure 1. Geographic distribution of 129 Solanum phureia occessions of the germplosm collection held at (IP.Squares indicate collection sites; the shaded area, the geographic area of S. phureia.

RAPD amplifications were performed fol­lowing a cost-effective protocol that we de­veloped for genotyping large germplasm col­lections at reasonable costs. The overall costof RAPD fingerprinting has been reduced byseveral measures such as reducing samplevolumes, recycling agarose gels, re-usingmicroplates, digitizing gel images, etc. Therunning cost is about US$0.17/reaction fol­lowing the protocol of ClP's molecular biol­ogy laboratory. DNA extraction and quanti­fication are sti II by far the most expensive costitem (US$1.47/sample). These estimates donot include staff salaries, equipment amorti­zation, and overhead.

Colombia

Peru

used a miniprep DNA extraction. DNA quan­tity was standardized by agarose gel electro­phoresis using highly purified DNA. We sepa­rated ampl ification products on agarose gelsand recorded them with a video image ana­lyzer. Genotypes were scored for the pres­ence (1) or absence (0) of each band. Fromthese data, we calculated a matrix of pairwisegenetic distances (Jaccard's distance) usingJaccard's similarity coefficient. We also usedmultidimensional scaling (MDS) to present therelationships between accessions. The statis­tical analysis used in the numerical taxonomyanalysis was done using the NTSYS-PC 1.80software.

78 Progrom 2

(IP Progrom Report 1995-96 79

Table 1. Selected RAPD primers for the Solanum phureja germplasm survey.

Each RAPD marker locus is expressed astwo alleles: presence and absence of theband. PIC values ranged evenly from 0.01 to0.50. The higher the PIC value, the more in­formative is the RAPD marker. This param­eter is useful to estimate the genetic distancesof two accessions in a large population orgermplasm collection. The PIC values for theRAPD markers generated by the same primerwere cumulated and have been named RAPDmarker index (Table 1). This index reveals theinformation content of the RAPD primer perassay. Therefore, primers OPR9, OPR13,OPZ4, and OPD20 (the four highest indexvalues) will be used in subsequent fingerprintresearch.

the polymorphic index content (PIC) = 1-SPj2,

where Pj is the allele frequency of the ith al­lele.

Genetic diversity assessment of theS. phureja collectionCluster analysis grouped the 163 acces­

sions into several large clusters at a high simi­larity level. Of these, 25 S. phureja accessionsfall mostly in one distinct group. This resultsupported the morphological observation thatthese 25 accessions are genetically differentfrom the rest of the S. phureja accessions. Re-

Results and Discussion

RAPD primer selection andmarker characterizationWe have screened a total of 106 primers

and selected the 12 most informative ones(Table 1), which generated 93 RAPD markerswith a broad range of allele frequencies.Three criteria were considered for primer se­lection: (1) reproducibility, (2) number of poly­morphic loci per assay, and (3) levels of poly­morphism detected in a specific population.Reproducibility is an intrinsic property of aparticular primer sequence, and hence canbe addressed only experimentally. The othertwo aspects can be quantified, and we pro­pose a single parameter to measure the infor­mativeness of a particu lar primer for geneticdiversity studies in an outcrossing species.

Polymorphic bands. Each RAPD primerproduces different numbers of polymorphicbands. We selected the RAPD primers withthe highest number of polymorphic bandsamong the 106 screened. Each produced atleast six polymorphic bands.

RAPD marker index. To characterize thecapacity of each primer to reveal or detectpolymorphic loci in our germplasm, we use

3.01.5

The S. phureja accessions make up a rela­tively homogeneous group. The multidimen­sional scaling (MDS) analysis (Figure 2) dis­plays a rather homogeneous distribution withlittle indication of subgrouping. We labeledthe accessions in the MDS plot according totheir geographic origin at the level of depart­ments (provinces) and found little accord be­tween geographic origin and genetic relation­ship. This further supports the conclusion thatS. phureja is a single, homogeneous cultivatedspecies that is different from other wi Id rela­tives of potato. It has a long history of domes­tication in the Andes, which may have keptthis native crop relatively isolated.

In the collection of 131 genotypes, sevenaccessions were classified doubtfully as S.phureja based on morphology. The MD5 plotshows that at least three of the seven weredistributed at the outer layers (Figure 2). Care­ful taxonomic examination is recommended

•••.......' .;:..

II .~.'!...... 1.-, ..

• II ~ I',j !.. ... i

Ji.. •... ~ '., •I_I ~~

• 1.1.II· •

0.0

Dimension 1

:..

-1.5

1.0

0.0

Dimension 22.0

-4.01-l-------r------...-------...-------!-3.0

-3.0

-2.0

-1.0

The cluster analysis was redone on the re­maining 131 genotypes using Jaccard's simi­larity coefficient. The coefficient ranged be­tween 0.53 and 1 and was used to develop aphenogram. The goodness of fit test for thecluster analysis resulted in a low correlation(r=0.76), suggesting that the cluster is poorlydefined. In general, there is no correlationbetween the marker-based grouping patternand the geographic origin.

Accessions collected from Colombia scat­tered across almost every cluster. So did theaccessions collected from Peru and Ecuador.This result indicates that it is not very usefulto subgroup these 131 S. phureja accessionsbased on their geographic origin.

80 Program 2

examination using morphological and pass­port data led to the conclusion that they wereactually from other Solanum species, mainlyfrom S. tuberosum subsp. andigena.

Figure 2. Multidimensional swling of the 131 Solanum phureia accessions. Solid triangles indicate doubtfulspecies assignment.

Ct)

:::>Ia...ooo

coC\I

:::>Ia...o()o

The analysis shows that in both cases(sample size of 16 and 35), marker-assistedsampling has higher molecular variance val­ues (i.e., genetic diversity) than random sam­pling (Figure 4). The value of Vm increased by17% when 16 accessions were sampled, andby 15% when 35 accessions were sampled.This result demonstrated the advantage ofusing marker data to construct a core collec­tion when the collection can be assimilatedinto a single population.

We divided the phenogram at 0.65 and0.70 values of Jaccard's similarity coefficient,which resulted in 16 and 35 clusters fromwhich one genotype was chosen at random.The diversity level in the selected sample wasmeasured by RAPD marker variance

Vm =S (npq)!(n-1 )where n = number of individuals, and p andq are the frequencies of the presence or ab­sence of a RAPD marker (Figure 4).

selects accessions from each stratum to maxi­mize the genetic distances in the samples.

1.15 KB1.09 KB

0.80 KB

Ct)

:::>Ia...ooo

coC\I

:::>Ia...ooo

1.15 KB

1.09 KB

0.80 KB

for these three clones as well as the onemarked with an arrow in Figure 2 to deter­mine their species identity.

Morphological data available for 106 ac­cessions did not allow us to clearly separate5 genetic groups of S. phureja accessions,which we therefore considered as suspectedduplicates. RAPD data resolved genetic dif­ferences between these clones in all cases. Aseparate analysis confirmed these results (Fig­ure 3). However, out of the 131 genotypesfingerprinted, two were found to be indistin­guishable for 93 RAPD markers. Hence, thenumber of suspected duplicates went downfrom 5 groups of 12 genotypes to only 1 groupof 2 genotypes.

(IP Progrom Report 1995-96 81

Molecular data and core collectionBased on molecular marker data, we used

the 131 accessions of S. phureja as a modelto compare sampling methods for a core col­lection. Two sampling methods were com­pared: (1) random sampling, and (2) marker­assisted sampling, which takes the marker­based clusters as stratas and systematically

Figure 3. Morphological duplicates of the Solanum phureia collection resolved by molecular assays: polymerasechain reaction amplification with primer OPR3 on the left and OPZ4 on the right. Arrows indicatedifferential markers.

TMV

RS35MS35

Hawkes, J.G. 1992. Biosystematics of thepotato. In: The potato crop. P. Harris(ed.). Chapman & Hall, London.p.13-64.

Selected Reading

The designated core collection will thenbe systematically evaluated for major agro­nomic traits so that the gene variation in thecollection will be better understood. Thesecore accessions wi II then be cleaned and

made available to germplasm users. This corecollection approach would allow us to betteruse our lim ited resources for rational izedmanagement of the potato germplasm collec­tion.

RS16MS16Global 131

10

12.5

12

13.5

10.5

11

11.5

14

13

Also, the number of core accessions shouldbe decided based on the retention of themaximum number of alleles. This procedurewill lead to a core subset covering the maxi­mum genetic diversity in the large collection.Based on this subset, curators and breederscould add certain genotypes known to pos­sess important agronomic traits.

To form a core collection, the large potatocollection held at ClP should first be sampledand stratified based on molecular marker

data. Then a sample should be taken fromeach stratum to represent each marker-differ­

entiated group.

Conclusions

82 Program 2

Figure 4. Total marker variance (TMV) for random (RS) vs. marker-assisted (MS) sampling of the Solanum phureiacollection using 16,35, and 131 genotypes.

Nienhuis, J., J. Tivang, and P. Skroch. 1994.Analysis of genetic relationships amonggenotypes based on molecular markerdata. In: Proceedings of the symposiumAnalysis of Molecular Marker Data. p. 8-15.

Ochoa, CM. 1990. Solanum phureja.In: The potatoes of South America:Bolivia. Cambridge University Press.p. 315-334.

CIP Progrom Report 1995-96 83

M. Ghislain, B. Trognitz, C. Herrera, A. Hurtado, and L. Portal1

DNA Markers for the Introgression ofLate Blight Resistance in Potato

We have worked in close collaborationwith scientists Rhonda Meyer and RobbieWaugh from the Scottish Crop Research In­stitute, and Susana Marcucci and EstebanHopp of the Instituto Nacional de TecnologfaAgropecuaria, Centro de Investigaci6n enCiencias Veterinarias, in Argentina. Molecu­lar markers have been developed to analyzehybrid popu lations, parental heterozygosity,and simultaneous segregation with pheno­typic scores. These tools are polymerasechain reaction (PCRl-based deoxyribonucleic

Materials and Methods

We have developed populations of diploidpotatoes that segregate for LB resistance fromthree accessions of a native cu Itivated potato,S. phureja. This diploid species was selectedfor its high levels of horizontal resistance toLB (leaf resistance), favorable tuber charac­teristics and culinary quality, and crossabil­ity with dihaploid potatoes. We are analyz­ing the three populations (VP, PD, and PP) atCIP for phenotypic segregation of resistanceusing a complex race of P. infestans (Table1).

At CIP, we have been applying moleculartechniques to unravel the genetics of horizon­tal resistance to LB in tuber-bearing Solanum

species, especially S. phureja and S.verrucosum. Developing detailed geneticlinkage maps using molecular markers willhelp us explain the genetic control and ar­chitecture of this quantitative trait. Thisknowledge and molecular tools wi II improvethe efficiency of the introgression of valuableresistance and defense genes from Solanumgermplasm into the cultivated potato.

tively expressed and induced upon pathogeninfection.

Researchers explained some of the geneticsof horizontal resistance to LB in the early1990s. Potato scientists have characterizedhorizontal resistance in several Solanum spe­cies and in interspecific hybrid progenies. Amolecular genetics study has even been de­veloped with a preliminary genetic map ofquantitative resistance to LB from an intraspe­cific S. tuberosum cross. This type of resis­tance is thought to be the result of severalindependent mechanisms that are constitu-

1 CIP, Lima, Peru.

84 Progrom2

Unraveling the Genetics ofHorizontal Resistance to late Blight

ClP's breeding strategy is to use horizon­tal resistance from novel sources to make re­sistance in potato to LB less dependent onpathogen races and hence more durable.Quantitative inheritance and the high load ofunfavorable genes in wild and native pota­toes, however, have impeded the broad useof this type of resistance to develop new po­tato cultivars.

Two types of resistance to late blight (LBlexist in this germplasm: vertical (governed bya specific gene-for-gene interactionl and hori­zontal (governed by several genes whose in­teractions are still largely unknown).

Resistance to late Blight in Potato

A major challenge in breeding for resistanceto late blight caused by Phytophthorainfestans in potato is to fully exploit tuber­bearing Solanum germplasm as a source forresistance to the disease. Indeed, germplasmused by breeders has a narrow base comparedto the potential available in Solanumgermplasm.

Resistance

Male parent

Identification

The marker value helps us select an ap­propriate marker system for a particular crossand allows us to predict costs in terms of timeand assays of building a genetic map. Again,the dihaploid (D) parent will on average pro­duce 2.7 scorable marker loci per RAPD as­say, whereas more than 20 are necessary forthe S. verrucosum (V) parent. Therefore, theDNA marker analysis led us to conclude thatthe genetics of LB resistance in the VP popu­lation will be studied more efficiently with asubsequent backcross in which the femalemarker loci will segregate.

[IP Progrom Report 1995·96 85

DNA markers in diploidhybrid potato populationsThe segregation of DNA markers in hybrid

populations has been analyzed separately formarkers that derive from each parent follow­ing a backcross model. All DNA markers havebeen treated as dominant markers in whicheach segregating band in the hybrid popula­tion is expected to have a 1: 1 segregation ratiofor presence-absence. This model allows usto analyze the data with MapMaker v3.0 soft­ware and to develop two genetic linkagemaps, one for each parent.

VP. In the VP (5. verrucosum x 5. phureja)population of 102 individuals, we scored sev­eral RAPD and AFLP markers that derive fromboth parents (Table 3). Chi-square (X2 ) tests

Resistance

Horizontal

Horizontal

Vertical and

horizontal

Female parent

phureio

S. phufeioCHS-625

S. verrucosum

63

Identification

Population Individuals

code (no.)

Table 1. Solanum germplasm used to map horizontal resistance to late blight.

acid (DNA) markers-randomly amplifiedpolymorphic DNA (RAPD), amplified frag­ment length polymorphism (AFLP), andmicrosatellites-and have been used on thefirst two populations only. The markers haveproven the hybrid nature of the VP and PDpopulations, a prerequisite for a breedingstrategy based on molecular genetics. Thesegregation of these markers in the progenyis indicative of the level of heterozygosity ofthe parents.

Results

Characterization of DNA markersDNA markers were scored separately for

each of the parents, leading to the definitionof two parameters: heterozygosity index (Hi)and a marker value (Mv). The heterozygosityindex of each parent is calculated here as theratio between segregating bands andnonsegregating scorable bands that corre­spond to either one of the two parents in theprogeny. The marker value is the averagenumber of informative DNA markers (poly­morphic and segregating) per assay. Theanalysis of more than 50 RAPD primers indi­cates by means of the Hi value that thedihaploid S. tuberosum clone is the most het­erozygous of the four (Table 2). In contrast isthe S. verrucosum parent, which barely showsany marker segregation.

Mv·

Polymorphic,segregation of the

band in 1:1

Hi·Locus

(no.)

Locus

Polymorphic,no segregation

PD. We also analyzed LB resistance ge­netically on the other diploid potato popula­tion, PO (5. phureja x dihaploid 5. tuberosum).We are now building genetic maps for theparents using 164 RAPD and 151 AFLP mark­ers, and 16 microsatellites (Table 3) on 94 PDhybrids. In contrast to the VP population, 81 %of the female parent markers and 68% of themale parent markers show Mendelian 1:1segregation in this interspecific hybrid prog­eny. Linkage analysis of the unskewed mark­ers, 118 female and 127 male, led us to de­fine 13 linkages for the female map and 16

coming from the 5. verrucosum parent. Weplan to analyze this source of resistance inthe offspring of the resistant hybrids.

Total

Monomorphic,segregation of the

band in 3:1

morphic AA Au

heterozygosity index, Mv = marker value.

Monomorphic,no segregation

VPl-1 16163 58 301 188 181 7 0.037 0.121

peeC81 58 353 113 240 130 110 0.458 1.897

PCHS-625 63 550 382 168 50 118 0]02 1.873

0 63 586 382 204 34 170 0.833 2.698

Parent

A: presence of the band; a: absence of the band

86 Progrom 2

Table 2. Characterization of diploid potato populations: segregation of dominant markers in hybrid progenies,heterozygosity index of parents, and marker value assessed by RAPD markers.

Of the 122 RAPO and AFLP markers scoredin this population from the male parent, 84(69%) did not deviate significantly from theexpected monogenic ratio. Linkage analysisbetween the 84 unskewed markers derivingfrom the male parent led us to define five link­age groups (using the default values ofMapMaker). The highly distorted segregationfor markers deriving from the female parentprevents a genetic analysis of the resistance

for goodness offit to the monogenic ratio 1:1revealed a high degree of distortion of segre­gation from the female parent of VP. Onlyeight markers (22% of the female parent mark­ers) from the female parent showed unskewedMendelian 1:1 segregation.

Table 3. DNA markers scared in the offspring of diploid potato interspecific crosses and association with lateblight resistance.

2

7

28

69

Male parent

Total Unskewed Putative LB

markers markers· markersb

ent. Five of the six markers from the 5. phurejaparent fall into three of the five Iinkage groupsby two-point analysis (Table 4).

(IP Progrom Report 1995-96 87

PD. Applying the single-marker loci analy­sis for linkage with phenotypic classes on thePD population resulted in the identificationof 17 DNA markers (Table 3). Nine markersfrom the female parent and eight from themale parent are associated (0.001 <P<O.OS)with sign ificant effects on resistance to LBobserved in a screenhouse assay. As expectedfor a polygenic trait, each of these DNA mark­ers correlates with small differences in phe­notypic values. Several markers fall into thesame linkage group (Table 4).

We hope to confirm this preliminary iden­tification of DNA markers associated with thesegregation of quantitative resistance to LBby extending the analysis to the entire PDpopulation of 254 individuals. Likewise, wewill collect phenotypic data from field trialsin 1997. We plan to finish constructing thegenetic map simultaneously for both parentsand carry out a quantitative trait loci (QTL)analysis by interval mapping methods, using

Female parent

Total Unskewed Putative LB

markers markers· markers b

Markers

VP RAPD 7 4AFlP 30 4

RAPD 6AFlP 82 62 3

6satellite

Population

DNA markers for resistance to late blightWe applied single-marker analysis to de­

tect Iinkages between genotypic classes (pres­ence or absence of the band) and their re­spective phenotypic values (LB resistance vs.susceptibility) using a two-sample Student'st-test. This test detects whether the means ofthe phenotypic values for two genotypicclasses differ sign ificantly.

for the male map. As a result of this analysisand earlier phenotypic evaluations, this PDpopulation displays the expected features ofa genetic material adequate for mapping hori­zontal resistance to LB.

VP. We have identified 7 DNA markers outof a total of 92 unskewed markers in the VPpopulation that are associated (0.01 <P<0.05)with contrasting phenotypic classes (Table 3).The trait values are the means of 3-yr fieldevaluations with indigenous complex races.This weak association can be explained bythe genotype x environment interaction andchanges in race complexity from year to year.One marker is from the female parent,whereas the other six are from the male par-

Table 4. linkage analysis of DNA markers associated with significant differences in means of late blight scores byStudent's t-test.

lG 2

lG 5LG 10

LG 12LG 13

LG 13Independent

Independent

LG 1LG 9

lG 9

lG 9LG 14

LG 14

lG 15Independent

lG 1lG 1

LG 4LG 4

lG5Independent

Independent

Marker linked

to group

0.05

0.050.050.050.010.010.01

0.05

0.010.05

0.05

0.05om0.050.05

0.05

0.050.050.050.05

0.050.05

0.05

P<

R

C

C

R

R

RC

R

C

R

R

R(

C

C

C

R

R

R

C

cR(

Coupling (C) or repulsion (R)

phose to late blight resistance loti

From dihaploid male in PO

B17.1750B2.250057.205054.600B8.1850

Z6.400G3.1000

E45M42.6

E45M42.3B6.140058.940

From S. phureiafemale in PO

Z10.550R9.1200518.500

From S. verrucosum female in VP

e73m67.8

From S. phureia mole in VP

E35m42.1e73m67.5e73m67.?e73m67.4

Z4.680R4.900

Markers

88 Progrom1

the chromosomal region between two mark­ers instead of a single marker.

Conclusions

This preliminary QTL analysis of two diploidpotato populations will be refined by high­resolution genetic analysis and by looking atdifferences in the expression of QTL for re­sistance under different environments andafter exposure to different races of the patho­gen. Confirmation of the value of each DNAmarker will be an important step in develop­ing new varieties with improved resistanceto LB. In this respect, the PP population (Table1) will be useful for testing the congruence ofLB resistance markers in S. phurejagermplasm.

This will be achieved by selectivegenotyping of the PP population with the PD­derived LB markers. By 1998, we will beginintrogressing valuable QTL from the PD popu­lation by applying marker information to helpselect good parental clones. We plan to make

new crosses at the diploid stage to verifycosegregation of these DNA markers withhorizontal resistance to LB. In the mediumterm, we will transform DNA markers that tagresistance QTL into an easy-to-use tool to se­lect new potato varieties with LB resistanceQTL with an S. phureja origin.

Selected Reading

Colon, L.T., R.C. Jansen, and D.). Budding.1995. Partial resistance to late blight(Phytophthora infestans) in hybridprogenies of four South AmericanSolanum species crossed with diploidS. tuberosum. Theor. App!. Genet.90:691-698.

Leonards-Schippers, c., W. Gieffers, R.Schafer-Pregl, E. Ritter, S.J. Knapp, F.Salamini, and C. Gebhardt. 1994.Quantitative resistance to Phytophthorainfestans in potato: A case study for QTLmapping in an allogamous plant species.Genetics 137:67-77.

(IP Program Report 1995-96 89

D.P. Zhang, M. Ghislain, Z. Huaman, F. Rodriguez, and J.C. Cervantes!

Identifying Duplicates in Sweetpotato GermplasmUsing RAPD

The reproducibility of the RAPD assay isof concern when applying RAPD to the iden­tification of duplicates. It is known that mosterrors occur when cross-lab, cross-plate (am­plification), and cross-gel comparisons aremade.

In our case, the highest number of sus­pected dupl icates in the sweetpotato genebank held at ClP is 20 accessions per group.Therefore, all within-group comparisons can

Large intervarietal variation in sweetpotatohad been found using randomly amplifiedpolymorphic DNA (RAPD) fingerprinting. Butwhether RAPD would reveal minimalintravarietal variation was not clear. Identify­ing duplicates in sweetpotato is complicatedby the fact that somaclonal mutation is fre­quent in this crop. Visible morphologicalchanges such as skin and flesh color of stor­age roots are common. Therefore, it is essen­tial to understand whether these mutations aredetectable by RAPD. And if they are, whatamount of difference is acceptable for a groupof accessions to be considered duplicates?

Three criteria were considered essential forany method to identify duplicates. First, themethod shou ld generate maximumintervarietal variation to ensure discrimina­tion between cultivars. Second, it should de­tect minimal intravarietal variation so thatclones of the same cultivar would have ahighly homogeneous identity. Third, it shouldhave good environmental stability and littletechnical error.

tivar identification in many other crops. Itspotential for sweetpotato, however, has yetto be assessed.

Duplicate accessions of sweetpotato havebeen routinely identified at CIP based on ClP­AVRDC-I BPG R2 sweetpotato descriptors.Duplicate identification within Peruviansweetpotatoes maintained in the field genebank held at ClP has so far reduced the sizeof the collection from 1,939 to 909 acces­sions. These duplicates were identical bothin their morphology and in their electrophore­sis banding patterns of proteins and esterase.

Sweetpotato (Ipomoea batatas (L.) Lam.) is ahighly heterozygous hexaploid crop. Vegeta­tive propagation is the only means to main­tain its varietal identity. Maintaining a largegene bank of a vegetatively propagated cropis costly, and it is difficult to meet increasinguser demands when faced with limited finan­cial and physical resources. More compre­hensive assessment of genetic identity is es­sential to reduce redundancy and save man­agement and operating costs of thegermplasm bank held at CIP. Accessions con­sidered redundant could be bulked into bo­tanical seeds, which are less costly to main­tain. Identification of dupl icates is also thefirst step in developing a core collection torepresent the genetic variabi lity avai lablewithin the sweetpotato gene pool and to makethe germplasm more accessible to users.

The introduction of polymerase chain re­action (PCR)-based DNA fingerprinting offersa novel tool for cultivar identification. Theadvantage of this technique is its sensitivity,simplicity, speed, and low cost. PCR-basedDNA fingerprinting has been applied to cul-

1 ClP, Lima, Peru.

2 IBPGR = International Board for Plant Genetic Resources,AVRDC = Asian Vegetable Research and DevelopmentCenter.

90 Progrom2

be made on the same plate and with the samegel, which greatly minimizes error. However,errors associated with quality and quantity oftemplate DNA, which occur mostly duringleaf sampling and DNA extraction, still needto be characterized.

Here we report our study of applying RAPDfor identifying sweetpotato duplicates. Weassessed the inter- and intravarietal RAPDvariation within a group of sweetpotato cul­tivars, characterized the error source, anddeveloped a procedure for identifying dupli­cates in the sweetpotato germplasm collec­tion. This study shows how molecular markertechniques play an important role insweetpotato germplasm management at ClP.

Materials and Methods

Suspected duplicate accessionsWe used 66 suspected duplicate acces­

sions in 15 groups for this study (Table 1).These accessions were originally collectedfrom Bolivia and maintained in the gene bankat CIP.

We grouped the suspected duplicatesbased on morphological observation, mean­ing that the accessions in the same group aremorphologically identical, or so similar thatthe descriptors cannot distinguish one fromanother. Their passport data, however, indi­cate they were collected from different geo­graphic locations. Fifteen accessions, one

Figure 1. TransgenicChogoku sweetpotato A

with dwarf mutation (A).Southern blot of

transgenic Chogokusweetpotato (B)

confirmed the insertionof the intron-GUS gene

into the genome.

from each suspected duplicate group, werechosen to assess intervarietal variation (Table1).

Plant material for measuringintravarietal variationTwo common U.S. Ipomoea batatas culti­

vars, Jewel and Beauregard, were collectedfrom three sources: U.S. Department of Agri­culture, Regional Plant Introduction Station,Griffin, Georgia; the sweetpotato breedingprogram of North Carolina State University,Raleigh, North Carolina; and the in vitro genebank held at CIP. These cultivars were usedas true duplicates to assess intravarietal varia­tion.

The in vitro plants were first transferred topropagation media for 2 wk and then to thescreen house. No morphological variationcou Id be detected between accessions of thesame cultivar from any of the three differentorigins.

A transgenic sweetpotato, Chogoku, ob­tained from the molecular biology laboratoryof ClP, was used as a simulated mutationclone. An intron-~-glucuronidase (GUS) genewas introduced into its genome viaAgrobacterium rhizogenes. The insertion wasconfirmed by a GUS assay and Southern blot.The transgenic Chogoku is also morphologi­cally distinguishable from the untransformedcontrol because of dwarfing induced by thetransformation (Figure 1).

CIP Progrom Report 1995-96 91

Table 1. List of 66 suspected cultivar duplicates in aBolivian collection.

92 Progrom 2

Duplicate

groupname

Native

Unknown 2009°

(arne Amarilla 2009

Ojiri 2010

Amarillo 20JOOUnknown 2011Amarillo 2011Morado 201 jO

Blanco 2011

Morado 2011Amarillo 2011Morado 2011

Blanco 2011

Peruono 2012Rosado 2012

Unknown 2012Guinda 2012

Unknown 2012°

Aguela Manuchio 2012

Amarillo 2012

Quebrodeno 2012

Morado 2012

Morado 2012

Morado 2012Colorado 2012Rosado 2013Rosado 2013

Raia 2013Blanco 2013°

Unknown 20WUnknown 2014Guindo 2014

Morado 2015Morado 2015°

DLP 1373

DLP 2723

DLP 1627

DLP 1600DLP 1360DLP 1363DLP 1376

DLP 1362

DLP 1368DLP 1622DLP 1621

DLP 1619DLP 1356

DLP 1359

DLP 1375

DlP 1352DLP 1374

DLP 1378

DLP 1372

DLP 1381

DLP 2733DLP 1379

DlP 2708DLP 2726DLP 1669DLP 1650DLP 1668

DLP 1666

DLP 1333DLP 1340

DLP 1334

DLP 1652

DLP 1659

Collection

number

200J0

2001

2001

2002°200220022002

2002

200320032003

2003

2003

2003

2003°

2003

20032004

2004°2004

2004

2005

2005

20052005°20062006

2006°2006

2007°2007

2008°

2008

Duplicate

groupnome

Native

Unknown

Blanco

Camote Blanco

AmarilloOglliriBlanco PintadoAmarillo

Apichu

OrientalMoradoJapones

Cruzena

Brasilero

Japones

Colorado

Comirino

Colorado

Rojo

Amarillo

Rosado

Blanco Papa

Tarijeno

Amarillo(0moteAmarillo

UnknownBlanco Larco

BlancoBlanco

Huilo ApichuApichu Amarillo

Corridor

Blanco

a. Accessions seleetedJor assessingintervarietol variation.

DLP 1332

DlP 1387

DLP 1658DLP 1384DLP 1377

DlPl383DLPl382

DlP 1370

DLP1380DLP 1637

DLP 1638

DLP 1366DLP 1602

OlP 1626

DLP2704

DLP1634DLP1618

DlP 1348

DlP1354

DLP 1353

DLP 1355DLP2721

DLP1349

DLP 1347DLP 1350HLP 1660DLP 1662

DLP 1636DLP1649

DLP 1327

DLP 1328

DLP 1635

DLP 1612

Collection

number

171211

13

1817

16

(IP Progrom Report 1995-96 93

Fragments

amplified (no.)

7

715

14

Intervarietal variationLarge intervarietal RAPD variation was de­

tected. Anyone of the 24 selected primers

Primer selectionA total of 80 Operon decamers were

screened on 10 accessions of sweetpotato. Aset of 24 primers was ultimately selectedbased on (1) the number of easily detectableand well-resolved polymorphic bands pro­duced and (2) the reproducibility of the samefragment pattern over repeated tests. We usedthese 24 primers to amplify a total of 164 poly­morph ic fragments from among all 15 acces­sions that had provided original data for cal­culating their genetic similarities. We alsoused these 24 primers to assay the true dupli­cates and transgenic plant. We used onlyseven of the most informative primers forgenotyping the 66 suspected duplicates (Table2).

where NAB is the number of bands sharedby individuals A and B, and NA and NB arethe number of bands in individuals A and B,respectively. The chance of finding two indi­viduals with the same fragment pattern canbe calculated as the mean similarity (5) to thepower of the mean number of bands (N).

Results and Discussion

CCACAGCAGTACCCCCGAAGGTCCACTGTG

B19

Mll

Material for characterizingerror source in RAPDThree factors associated with consistency

of RAPD profiles-age of leaves, sample con­tamination, and template DNA concen­tration-were characterized. Cultivar Jewelwas used for these tests. To assess the effectof leaf age on RAPD fingerprints, leaves fromnode 3 or above were compared with leavesfrom node 6 or older.

2 x NAB/NA + NB

To test the contamination effect, four youngleaves from pathogen-tested plants were com­pared with those of field-grown plants. Fivelevels of template DNA concentration rang­ing from 1 ng/lll to 20 ng/lli were used to testthe effect of D~~A concentration.

Gel scoring and data analysisDifferent fragments produced with each

primer were numbered sequentially and thepresence or absence offragments in each in­dividual was scored. Individuals from thesame row on one gel were compared witheach other. Fragments with the same mobil­ity on the gel but with slight differences inintensities were not distinguished when ac­cessions were compared with each other. Thesimilarity between accessions is calculatedas:

Table 2. list of seven primers used for identifying the 66 suspected duplicates and the number of bands theyamplified.

$ C\J '<t CD '<t 0 CD t"- If) C') 0 C') '<t CD C') <J) C\J $C') co C\J If) If) C') C\J C') t"- o CD t"- CD C') If)

2 C') C') CD C') C') CD C') CD C') CD C') C') CD C') CD e e 2C- o:: 0:: 0:: 0:: 0:: 0:: 0:: 0:: 0:: C- o:: 0:: 0:: 0:: c C....l ....l ....l ....l ....l ....l ....l ....l ....l ....l ....l ....l ....l ....l ....l 0 8Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl ()

Figure 2. RAPD revealed intervarietal variation of 15 Bolivian cultivars by oligonucleotide primer B14. Lanes 1and 19 are a 1 kb DNA ladder. Lanes 17 and 18 are controls.

That is not to say that these identified du­plicates are genetically identical. One cannever prove that two accessions are geneti­cally identical unless the sequence of theentire genome is known. We based our des­ignation as duplicate on the average genetic

Identifying suspected duplicatesTo test whether three primers would be

enough to identify duplicate cultivars withacceptable accuracy, the seven most infor­mative primers were sequentially applied tothe 15 groups of suspected dupl icates (Fig­ure 3). The first primer identified 58 dupli­cates out of the 66 accessions. The secondprimer improved the result by discriminating1 more accession, thus reducing the total ofduplicates to 57. The result remained con­stant even as more primers were used, indi­cating that three primers will give enoughaccuracy for identifying duplicate accessionsin sweetpotato.

Even when a group of 20 suspected dupli­cates is compared (180 pairwise compari­sons), the chance of misidentification is 3.89x 10-4

• This simplistic calculation shows that

RAPD is extremely efficient in detectingintervarietal variation in sweetpotato. That isbecause sweetpotato is a highly heterozygousoutcrossing crop and great genetic differenceexists between cultivars.

unambiguously differentiated all of the 15cultivars (Figure 2). The genetic similarity wascalculated for all the possible pairwise com­binations of the 15 cultivars. It ranged from0.44 to 0.69, with a mean of 0.61. Each primerproduced eight bands in this case, so whenone primer is applied, the probability ofmisidentification (two different cultivars bychance possessing the same RAPD profile) is0.618 , that is, 0.0192. When three primersare applied, the chance of misidentificationbecomes negligible (7.05 x 10-6).

94 Program 2

Figure 3. RAPD fingerprints of suspected duplicate groups generated by oligonucleotide primer B8. The molecularweight standard (MW) is a 1 kb DNA ladder. Table 1 describes the groups. Accession DPW 2653 ingroup 16 was not found to be a duplicate.

"""(') O'l CD O'l 0 CD (') 0 """

t'- 0 CD (')

3: CD O'l l!) C\J CO C\J CO CO C\J O'l t'- CO CD l!)l!) l!) t'- l!) t'- t'- t'- CO (') t'- 0 C\J CD l!) CD CD (')

"""(') l!) l!) CD CD CD CD

::2: (') (') (') (') (') (') (') (') t'- (') t'- t'- CD CD CD CD (') (') (') CD CD C\JC\JC\J C\JC\J C\J C\J

3:3:3: 3:a- a- a- a- a- a- a- a- a- a- a- a- a- a- a- a- a- a- a- a- a-....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I ....I a-a-a- a-0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 000 0

(IP Program Report 1995-96 95

Sweetpotato has a DNA content of roughly2c=5.0 picograms (pg) as estimated by flowcytometry. One pg of DNA is approximatelyequivalent to 965 million base pairs. There­fore, sweetpotato should have a genome sizeof roughly 8.04 x 105 kb. Assuming eachprimer can score 2 kb, the 24 primers usedin this study scored at most 48 kb of the 8.04x 105 kb sweetpotato genome. In addition,the complete sequence of the ampIified prod­uct of RAPD is not known. A primer may pro­duce identical-size products in two geno­types, but possible divergence within the in­ternal sequences cannot be detected. In thecase of the transgenic Chogoku plant, onewould need to apply 4 x 105 primers on aver­age to be able to detect the mutation, assum­ing it is caused by a single insertion. Thus, itis unlikely that RAPD will be useful for de­tecting intravarietal variation resulting fromsomatic rearrangements.

distance between cultivars from the samegeographic origin. For that reason, the iden­tified duplicates will not be eliminated. Theywill be planted in a crossing nursery and con­verted into botanical seeds, with only one ofthem being conserved as a unique cultivar invegetative form.

Intravarietal variationWith 24 primers and 125 polymorphic

bands, neither Jewel nor Beauregard showedany intravarietal RAPD variation. Clones col­lected from the three sources all revealed thesame profi les. Moreover, these polymorph icmarkers revealed no differences between thetransgenic Chogoku and the untransformedcontrol, even though the transgenic plant wastaller. This result suggests that althoughsomaclonal mutation is frequent insweetpotato, intravarietal variation is notreadily detected by RAPD.

This result also suggests the important andcomplementary role of morphological iden­tification. To identify duplicates, one shouldalways use morphological characters first.Application of DNA fingerprints should bebased on sound work of morphological iden­tification.

Error and repeatabilityThere were visually detectable differences

between older leaves (node 6 or older) andyoung leaves (node 3 or above). The RAPDassay using older leaves gave less satisfac­tory results, such as faint bands or inconsis­tent band intensity (data not presented). Theeffect of tissue age on RAPD banding patternmay be due to the polysaccharides presentin older leaves, which affect DNA quality.Thus, it is necessary to sample young leavesfor DNA extraction.

The leaves sampled from the field genebank did not give a different RAPD profilefrom that of the in vitro plant. Our experi­ence shows that one can take samples directlyfrom the field, as long as healthy young leavesare sampled.

A difference in RAPD banding pattern wasfound in the template DNA concentration test.A low concentration (1-5 ngllll) tends to re­sult in missing bands of low molecular weight.It is difficu It to avoid such error, because theDNA quantification is usually not accurate.In fact, this is the only significant error forduplicate identification. We recommend re­peating the RAPD test with different DNA ifthe suspected duplicate accessions only showdifferences in one or two low molecularweight bands, whereas the rest of the bandsare the same.

Conclusions

Several conclusions can be drawn from thepresent study. First, RAPD offers a reliablemethod for sweetpotato cultivar identification.It has distinct advantages over many bio­chemical methods such as isozyme and pro-

96 Program 1

tein assays, which are susceptible to environ­mental and developmental variations. A com­bination of three selected primers can unam­biguously confirm duplicates in thegermplasm bank held at ClP.

Second, morphological identificationshould always be the first step in groupingsuspected duplicates. RAPD can then be ap­pi ied to verify the morphological result. Basedon good morphological characterization, theRAPD comparison can be conducted on alimited number of accessions so that the com­parison can be made in the same gel. Thatmakes the operational error negligible, be­cause cross-plate and cross-gel comparisonsare avoided.

Third, RAPD is unsuitable for assayingintravarietal variation in sweetpotato. There­fore, it cannot be used to monitor clonal ge­netic stability in the gene bank or to detectsomaclonal mutation in sweetpotato.

Using RAPD for identifying sweetpotatoduplicates is now routine at ClP. We estimatethat about 30-40% of the 5,400 sweetpotatoaccessions are dupl icates. The identificationof redundancy will eventually save about 30­40% of the maintenance cost of the genebank. The downsized collection will also pro­vide a much better base for constructing acore collection. Minimum redundancy is thefirst requirement for a meaningful core subset.

Selected Reading

Bailey, D.C. 1983. Isozyme variation andplant breeders' rights. In: S.D. Tanksleyand T.J. Orton (eds.). Isozymes in plantgenetics and breeding, part A. Elsevier,Amsterdam. p. 425-441.

ClP, AVRDC, IBPGR (International PotatoCenter, Asian Vegetable Research andDevelopment Center, International Boardfor Plant Genetic Resources). 1991.Descriptors for sweetpotato. Huaman, Z.(ed.). International Board for PlantGenetic Resources, Rome, Italy.

D.P. Zhang, M. Ghislain, Z. Huaman, A. Golmirzaie, and R. Hijmans1

RAPD Variation in Sweetpotato Cultivarsfrom South America andPapua New Guinea

elP Progrom Report 1995-96 97

Plant materialsThirty-six sweetpotato cultivars from Co­

lombia, Ecuador, Peru, and Papua New Gui­nea (PNG) were used in this study (Table 1).

Materials and Methods

1. Is Oceanian sweetpotato necessarily dif­ferent from that of South America?

2. What is the genetic diversity level in theOceanian gene pool?

In this study, genetic variation is based onDNA sequence variation revealed by ran­domly amplified polymorphic DNA (RAPD).Assuming that all the RAPD fragments arerandomly located on the sweetpotato genomeand are selectively neutral, the genetic differ­ence in two groups of genotypes can be sta­tistically tested by the analysis of molecularvariance (AMOVA). The genetic diversity ina group of genotypes can also be measuredby the mean genetic relationship between allpossible pairs of individuals within that group.This survey should shed more light on thedistribution of sweetpotato diversity and helpto rationalize our sweetpotato germplasmcollection.

where sweetpotato can be found growing ataltitudes of up to 2,800 m. As a result, ClPand Indonesian scientists at the Root and Tu­ber Crops Research Center, CenderawasihUniversity, are conducting an in situ conser­vation project in Irian Jaya (the western halfof New Guinea).

As a preliminary step in the genetic diver­sity assessment, we recently comparedOceanian and South American sweetpotatogermplasm to answer two basic questions:

It is commonly accepted that sweetpotato(Ipomoea batatas (L.) Lam.) is of Central andSouth American origin, with its center of di­versity in northwest South America.Sweetpotato was dispersed to the Old Worldduring the sixteenth century, except for a sug­gested prehistoric spread from South Americato eastern Polynesia in 400 A.D. The crop'soutcrossing nature, combined with vegetativepropagation, has created a vast number of cul­tivated genotypes around the world sincethen, in spite of the relatively short dispersalperiod.

Nearly 8,000 accessions of sweetpotatohave been collected and maintained at vari­ous gene banks around the world, with themajority of them maintained at CIP. Knowl­edge of the distribution of genetic diversity isessential for rational germplasm conservation.Information on diversity distribution is alsocrucial to constructing core collections. Corecollections are a limited subset of accessions,from a large germplasm collection, chosento represent the genetic spectrum in the wholecollection. Maximum genetic diversity is thekey to establishing a good core subset.

1 CIP, Lima, Peru.

Sweetpotato cultivars in Oceania, particu­larly those in New Guinea (including PapuaNew Guinea and Irian Jaya Province of Indo­nesia), have long attracted curators' attention.This area was suggested as part of the sec­ondary diversity center of sweetpotato. Thereis evidence from ancient forest clearance thatsweetpotato might have reached the NewGuinea highlands some 1,200 years ago.More than 5,000 cultivars have been devel­oped under these isolated ecological condi­tions. The island is the only place in the world

Table 1. Nome and code of 36 sweetpotato cultivars from two geographic regions.

98 Progrom 2

Name

Unknown

Unknown

Morado

TijeretaDedulce (A)UnknownBlanco

Dedulce (B)UnknownMoradoChilpeJoponesMoradoAmarilloUnknownOreio de Galgo BlancoMeaManiaMena

GorohakoweAiva

Koitaki 2Oakasum

l312SamsKombo Nomongambalimo 1HapomuntoFaiv-MunYunpi

Collection no.

DiP 1873DlP 1898DlP 1001

DlP 1735DlP 1149DlP 1257DLP 1453OlP 1493OlP 1207

OlP 1404DlP 953OlP 2008OlP 3309

OlP 2213ReB IN 49100442100450100462100475100524

100509100934100497100849100453

Origin

Colombia

Colombia

ColombiaColombiaColombiaEcuadorEcuadorEcuadorEcuadorEcuadorEcuadorEcuadorPeruPeruPeruPeruPeruPeruPo pua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New Gu ineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPapua New GuineaPo pua New GuineaPapua New GuineaPapua New Guinea

The plant materials were obtained from thesweetpotato gene bank held at ClP. Healthyyoung leaves were collected from each ac­cession maintained in a screenhouse and invitro culture. The leaf tissue was immediatelyquick-frozen in liquid nitrogen, then freeze­dried. The freeze-dried leaf tissue was thenused for genomic DNA isolation using aminiprep procedure.

DNA amplificationsWe screened 80 random decamer oligo­

nucleotides as single primers for the amplifi­cation of RAPD sequences. Amplification wasperformed in volumes of 15111 containing 1.5III of the lax buffer, and 100 11M each ofdNTP, 0.4 11M primer, 25 ng genomic DNA,and 1 unit of polymerase. The reaction mixwas overlaid with 50 III mineral oil. Amplifi­cation was performed in 96-well microtestplates using a Teche PHC-3 thermal control­ler programmed for 41 cycles of 1 min at93°C, 1 min at 33°C, and 2 min at n°e. Am­plification products were analyzed by horizon­tal gel electrophoresis in 1.5% agarose gelsin 1x TBE buffer at 100 v for 5 h and detectedby ethidium bromide staining. Gels were pho­tographed using the Stratagene system.

Scoring and data analysisWe treated different fragments produced

with each primer as a unit character, and thennumbered them sequentially. We scoredgenotypes for the presence (1) or absence (O)of each fragment. Only those fragments withmedium or high intensity were taken intoaccount. Fragments with the same mobilityon the gel but with different intensities werenot distinguished from each other when cul­tivars were compared. Monomorphic frag­ments were not scored.

From these data, a matrix of pairwise ge­netic distances based on simple matching co­efficients (SM) was calculated as Dij =1 - SM.

The AMOVA procedure was used to esti­mate variance components for RAPD pheno­types. Variation was partitioned among indi­viduals (within regions) and between regions.The variance components of interest were ex-

tracted and tested using nonparametric per­mutational procedures.

Multidimensional scaling (MDS) of NTSYS­PC was used to present the relationships be­tween the 36 cultivars.

The genetic diversity within PNG andSouth American cultivars was measured bythe mean genetic distance and total markervariances.

Results

Of the 80 primers screened in this study, 15were selected because they all revealedmultibanded fingerprints, which are clearlyscorable (Table 2). All 36 cultivars can be dif­ferentiated by anyone of the selected prim­ers (Figure 1). Their replicability in amplifi­cation was verified by three runs of poly­merase chain reactions (PCR) using templateDNA from five sweetpotato cultivars. Thesereactions are highly consistent. Since the re­sults were consistent between replications,amplifications with all 36 cultivars were re­peated for each primer only when obviousproblems with the PCR procedure occurred.

The 15 selected primers yielded 89 poly­morphic and clearly scorable fragmentsacross the 36 cultivars. On average, approxi­mately six polymorphic bands were observedfor each primer (Table 2). Of the 89 scoredmarkers, only eight are region-specific(present in one region but absent in another).The rest of the markers vary in frequency be­tween regions.

The between-region variance contributesonly 10% of the total molecular variance; thewithin-region variance accounts for 90%.Nevertheless, using a nonparametric test with1,000 permuted matrices, we found that thebetween-region difference was significant(Table 3). This indicates that there is a sub­stantial difference between PNG cultivars andtheir South American counterparts in RAPDvariation.

The genetic diversity within Papua NewGuinea and South American groups, mea-

CIP Program Report 1995-96 99

-ow

• ..-

149

13

1198

13

1012

1211

10

14

1313

172

Fragments

amplified (no.)

~~. --­..'.. -•

6

847

89

6

459

74

10

45

The difference between these two groupsof cultivars in terms of genetic constitutionand genetic diversity is also reflected in theMDS plot (Figure 2). The PNG cultivars aregrouped together in a much smaller range,

••111-•••••••••• •••

Polymorphic

fragment scored (no.)

­.,.'-

GTCCACACGG

TCCGGaGGTTTGCCCGGAGGCGGTIGTGCCGTGAGCA

Oligonucleotide

sequence 51 to 3'

Total

OPM-04

Primers

OPB-08

•MW 1 2 345 6 7 8 91011121314 15MW16171819 202122 23 2425 26 2728 2930 313233 343536MW

Figure 1. RAPD fingerprints of 36 sweetpotato cultivars generated by oligonucleotide primer 816 (the nucleotidesequence is given in Table 2). The numbers on top refer to the sweetpotato cultivars listed in Table 1.The molecular weight (MW) standard is 1 kb DNA ladder.

100 Progrom2

sured by the total marker variance and themean genetic distances between all possiblepairs of individuals within a region, is alsosignificantly different. South American culti­vars had a significantly greater diversity thanPNG cultivars (Table 4).

Table 2. List of primers used in the RAPD analysis and their respective oligonucleotide sequence.

Repl icabi Iity is one of the primary concernsin using RAPD as a DNA fingerprint. Our re­sults show that with properly selected prim­ers and optimized amplification conditions,results are highly replicable. When a largecollection of germplasm needs to be assessedfor genetic diversity, RAPD is certainly oneof the most cost-effective and user-friendlytools.

identify cultivars and assess genetic diversityin sweetpotato.

Although the prehistoric existence ofsweetpotato cultivation in Papua New Guinea

MSD"

0.569

0.188

CIP Program Report 1995-96 101

whereas the South American cultivars aremore widely scattered in the plot.

Discussion

Table 3. Analysis of molecular variance (AMOVA) for RAPD variation between South America and Papua NewGuinea (PNG).

A high degree of variability in RAPD markerswas observed in sweetpotato. All 36 cultivarsevaluated can be differentiated with a singleprimer. It appears that enough markers canbe generated by a few selected primers toenable a comparison of different cultivargroups. This high resolution power, in con­trast with the very low level of allozyme andprotein polymorphism observed earlier, dem­onstrates the effectiveness of using RAPD to

Table 4. Total marker variance, mean genetic distance and nonparametric test of variances for Papua NewGuinea and South American sweetpotato cultivars.

Dimension 22

2

A100462

DLP10010

DLP 12070

100934 A 101369100618A

100497A A A A 100453A 100601

101367100509 A 100561

101361 t 100475A A 100524A A

100928 100846 A 100450tA

100849

Assessing diversity is also important for theconstruction of a core collection. A stratifiedsampling method can be used when estab­lishing a core subset. RAPD data, which par-

Our other major interest, besides the ge­netic differences between PNG and SouthAmerican cu Itivars, is the genetic diversitylevel within PNG and South American geno­types. The significantly lower diversity levelwithin PNG cultivars, compared with SouthAmerican samples, is not unexpected sinceSouth American cultivars sampled were fromPeru, Ecuador, and Colombia-the center oforigin of sweetpotato. The Oceanian genepool, in contrast, is a comparatively recentarrival from a more ancient distribution.

Guinea cultivars, after many years of inde­pendent evolution and selection in an isolatedenvironment, are indeed genetically distin­guishable from their ancestors in SouthAmerica.

DLP 17350

oDimension 1

DLP 3309o

DLP18730

DLP 14530

DLP 18980

DLP 9530 DLP 221 3000

DLP 1257 ReB IN49 A 100442

DLP 14040

ARB 4880

·1

DLP 17050

oDLP 1493 DLP 12230

DLP11490

-2

o I-

1 I-

-2

-1 I-

102 Program 2

Sweetpotato is an outcrossing hexaploid;variation because of sexual reproduction and

somatic mutation can be fixed by its vegeta­tive propagation. It is not surprising then tosee such large variation between individualcultivars. When AMOVA is used to partitionregional differences against a background ofamong-individual (within-region) polymor­phism, it quantifies the cumulative impact ofthe difference in frequency of polymorphicmarkers between PNG and South Americancu Itivars. Resu Its suggest that Papua New

I0 South American cultivars IA Papua New Guinea cultivars

has yet to be proved, sweetpotato has becomea staple food there. The crop is cultivatedextensively in the highlands of New Guinea,unlike in the rest of the world where it ismostly a lowland crop. This study shows thatthere is a substantial difference between PNGand South American cultivars, although thedifference is small relative to the large differ­ences between individuals within each re­gion.

Figure 2. Multidimensional scaling plot of 36 sweetpotato cultivars based on simple matching coefficients fromRAPD markers.

tially reflect the distribution of diversity, cantherefore be used as one criterion to help as­sign accessions to appropriate groups.

Conclusions

Several conclusions can be drawn from thepresent study. First, PNG cultivars, after manyyears of independent evolution in an isolatedagroecological environment, are substantiallydifferent from their ancestors in SouthAmerica.

Second, the genetic diversity level in PNGcultivars is significantly lower than that inSouth American cultivars.

Third, the RAPD technique or DNA mark­ers in general can reveal useful informationabout the genetic relationship and geneticdiversity in sweetpotato, which morphologi­cal markers cannot detect. Therefore, itshould be used as a major tool for the assess­ment of genetic relationship and genetic di­versity in sweetpotato germplasm.

This is our first experiment in assessing glo­bal sweetpotato diversity. More research witha larger sample size, involving different im-

portant sweetpotato gene pools, is under wayat OP. We believe that these results will pro­vide us with the information needed for ra­tional management of global sweetpotatogermplasm.

Selected Reading

Austin, D.F. 1988. The taxonomy,evolution and genetic diversity ofsweetpotatoes and related wild species.In: P. Gregory (ed.). Exploration, mainte­nance, and utilization of sweetpotatogenetic resources. CIP, Lima, Peru.p.27-60.

Excoffier, L., P.E. Smouse, and j.M.Quattro. 1992. Analysis of molecularvariance inferred from metric distancesamong DNA haplotypes: Application tohuman mitochondrial DNA restrictionsites. Genetics 131 :479-491.

Nienhuis, j., j. Tivang, and P. Skroch.1994. Analysis of genetic relationshipsamong genotypes based on molecularmarker data. In: Proc. Analysis ofMolecular Marker Data. joint PlantBreeding Symp. Ser., Am. Soc. Hort.Sci. and Crop Sci. Soc. Am. Minneapo­lis, Minn. p. 8-14.

ClP Progrom Report 1995-96 103

II-Gin Mok\ Tjintokohadi\ Lisna Ningsih\ and Tran Due Hoang2

Sweetpotato Breeding Strategy andGermplasm Testing in Southeast Asia

countries. For the tropics, we need to esti­mate h2 again to predict the progress of a se­lection cycle.

The Breeding Strategy

While evaluating various introductionsfrom many countries, we realized that seedfamilies from Japan produced a large num­ber of progeny with very high DM content.Obtaining botanical seed from Japan was dif­ficult, because seed production by hand-pol­lination was expensive. Moreover, all of therecently released varieties, which are fre­quently used for hybridization, are protectedunder Japan's Breeders' Rights Law.

Convergent-divergent selection andclonal poolWe receive seeds from various regions or

sources to form a base population (Figure 1).Seeds are planted and superior clones areselected and intercrossed. Small packages ofseeds of the F

1popu lation are returned to each

site where selection continues. Clones se­lected at each site are intercrossed, and seedsfrom those populations are sent again to the

To overcome the limitations to using Japa­nese breeding material, shuttle breeding wassuggested. Hybrid seeds produced by atrainee working with the national breedingprogram in Japan could be sent to the CIPregional office in Bogor, Indonesia, for evalu­

ation and distribution to countries in the re­gion.

ExplanationTo take advantage of ClP's decentralized

breeding activities, we modified the conver­gent-divergent selection scheme for sweet­potato improvement.

Sweetpotato (Ipomoea batatas) has long beenused as food and feed in Asia. It grows wellunder relatively poor fertility and low soilmoisture. Sweetpotato produces the highestamount of energy (194 MJ/ha per day) of allcrops. Production, however, is decreasingwith economic development in the region.Through processing, the crop will become avalue-added commodity. Most varieties nowcultivated have low dry matter (DM) content(25-30%), too low to be used as raw materialin the processing industry, which prefers DMabove 35%.

We already know, from heritability estima­tion and additive gene action, how to increaseDM content. The CIP regional breeding pro­gram, however, targets many countries (orlocations) in the region. We must thereforemaintain various useful genes for yield, stor­age-root qual ity, and pest resistance whi Ie

increasing mean DM content in each selec­tion cycle.

1 C1P-ESEAP regional office, Bogar, Indonesia.2 Vietnam Agricultural Sciences Institute, Hanoi, Vietnam.

Wide adaptability is also important for theregional breeding program. To achieve thatgoal, we adopted and modified a breedingscheme already used by maize breeders inthe United States--the convergent-divergentselection scheme. The convergent-divergentscheme for sweetpotato breeding involves (1)maximizing the use of diverse genetic re­sources, (2) promoting collaboration amongbreeders (CiP region and national agriculturalresearch systems), and (3) selecting varietiesfor wide adaptabi Iity. Heritabi Iity can be usedas an indicator for selecting a specific trait inbreeding programs. Both broad (H) and nar­row (h2

) sense heritabi Iity have been esti­mated by many researchers in temperate

104 Program 2

Figure 1. Convergent-divergent selection scheme, which maximizes the efficiency of decentralized breedingprograms.

5'

5

12345

43

Evaluation of new introductionsNew introductions from ClP, Japan, and

China were evaluated at Bogor for adaptabil­ity and OM content. ClP440049 (cv. Mojave)and ClP440230 kv. Satsumahikari) had thehighest OM content and moderate yield.Satsumahikari was very susceptible to vari­ous diseases and may be useful only as a pa­rental clone. CIP400004 and CIP400016 gavehigh yield, but OM content was low (-29%).Three introductions from Japan were veryhigh in OM content (34-40%), but their yieldwas moderate or low. One of them, Hi-starch,

will be replaced with better ones to ensurethat the clonal pool always contains the bestpossible clones.

(IP Progrom Report 1995·96 105

Some of the clones in the clonal pool willbe used to make crosses. Seeds will also beprovided to collaborating breeding programsas improved material. Some clones from theclonal pool will be ready to distribute aftermeristem culture and pathogen testing.

2

l'

1

12345

Localpopulation

Selectionintercross

Selectionintercross

Sweetpotato seed families introduced frommany countries as part of the modified con­vergent-divergent breeding scheme were firstplanted at Bogor for evaluation. Clones wereselected for high OM content and reasonablyhigh yield. Most clones have light-coloredflesh varying from white to yellow. Becausethe objective of this program focuses on in­dustrial use, skin color was not a selectioncriterion.

coordinating site. During selection cycles andintercrossing, each region can add newly ac­quired elite germplasm for introgression ofspecific genes. This method adapts well tosweetpotato breeding at ClP, whose breedersare based at many sites around the world.

We plan to maintain about 100 clones con­tinuously as a clonal pool to provide goodmaterial for further selection at different sites.As new clones are selected from seedlingevaluation ~ observational evaluation ~ pre­liminary evaluation, poorer performing clones

a successful variety in Japan for starch pro­cessing, was very susceptible to weevil (Cylasformicarius). Many Chinese varieties werehigh yielding and had good adaptability, butall were low in DM content, far below that ofthe local checks.

Many ClP pathogen-tested clones weretested for DM content at Bogor for more thantwo seasons. A few clones varied in OM con­tent, but the variation of most of them waswithin the acceptable range of about 2%.Among tested clones, ClP 440042 (cv.Macana), CIP440045 (cv. Toquecita),ClP440121 (cv. Naeshirazu), and ClP440146(IRA-1592) gave high OM content over at leasttwo seasons. ClP400004 (CEMSA 74-228)was also stable, yielding about 30% OM con­tent over three seasons. These clones werechosen as parents for the convergent-diver­gent selection scheme.

Estimating Heritability forDry Matter Content

Twenty-two parental clones were selected inpreliminary experiments. Some were intro­duced from CIP-Lima; the others were col­lected in Indonesia. These parental cloneshave varied OM content, good flowering, andhigh yield. Parental clones were planted in afield isolated from other sweetpotatoes, andopen-pollinated by natural vectors such asbees. Seeds were collected 30-35 d after flow­ering. Parental clones were multiplied by tak­ing cuttings from existing plots. Viable seedswere obtained from 18 clones (Table 1). Theseseeds were used for the heritability study.

Parental clones and their offspring wereevaluated for yield and OM content in a sepa­rate but adjacent field at Muara ExperimentStation, Bogor, in 1995. The field was har­vested 150 d after planting. The plot size was5 m x 1 m, with two rows for each progenyfamily, and a single row for each parentalclone. Both the offspring and parental cloneswere tested in a randomized complete blockdesign with four replications. Five individualprogenies were selected based on a storageroot large enough for sampling OM contentand free of disease or insect damage. Five stor-

106 Prog<am 2

age roots were selected from each individual;each storage root was cut into four longitudi­nal sections. The longitudinal sections, eachfrom 4 or 5 storage roots, were sliced intostrips and mixed well. After 100 g of slicedstrips were weighed, the sample was dried inan electric oven for 8 h at 80°C and 6 h at105°e. OM weight was measured to calcu­late OM content.

Heritability was estimated by simple lin­ear regression of the response of the mater­nal parents against the mean response of theirhalf-sibling offspring. Estimation of h2 wascalculated by doubling the regression coeffi­cient (b) for each parameter. Heritability wasobtained for OM content, storage roots/plant,storage root weight/plant, storage root size,plant survival rate, and resistance to scab(caused by Elsinoe batatas).

The h2 of the storage-root OM content was61.2 for family and 58.6 for individual re­sponse (Table 2). The high h2 of family andindividual observations in this study agreedwith the estimates of other researchers in tem­perate regions. Heritability of OM content ishigh enough to make rapid progress withphenotypic selection in a breeding program.

OM content of parent and offspring gavean interesting result. Frequency distributionof progeny according to the OM content ofindividual plants could be categorized intothree groups (Figure 2). In group A, with fam­ily BB94505 as an example, most progenieswere lower in OM content than their paren­tal clone. In group C, most progenies werehigher in OM content compared with theirparental clone. In group B, the parental clonewas about in the middle of the frequency dis­tribution. Group A has three families, groupB has seven, and group C has eight. Thisgrouping indicates that just one cycle of re­combination increased the family mean OMcontent, although there was no direct selec­tion exerted toward high OM content. Paren­tal clones offamilies BB94517, BB94518, andBB94514 had the lowest OM content of allparents (Table 1). OM content of BB94517was 21.5%; BB94518, 23.9%, and BB94514,26.8%. However, the mean OM content of

C

8AB

8(

C

8

C8B

Family

from

Figure 2

Range of

27.1-40.726.0-41.528.4-39.630.0-38.1

25.1-37.924.2-40.4

24.8-42.2

30.6 def

3332.9 abed32.6obede32.3 obedef

34.1 obc34.0 abed

Mean

OM content'

(%)

Conclusions

elP Pragram Report 1995-96 107

The modified convergent-divergent breedingprogram for sweetpotato has permitted de-

From 14,256 pollinations, 8,910 seedswere harvested. About one-third were sentto Vietnam; the rest were sent to CIP-Bogor.The seeds will be sent to breeding programsin other countries in the region to select highDM clones.

flowering using Ipomoea nil as rootstock.Parental clones grown in pots were placed ina greenhouse to isolate them from pollinat­ing insects.

Family

BB94501BB94510BB94511BB94507BB94513BB94512BB94506BB94520BB94517BB945188894514

8894504889450388945198894509

28.7-29.6

Range of

DM content

29.3-31.8

32.5-34.733.3-36.6

33.2-35.933.7-35.329.2-30.4

34.50

Mean

OM content"

a

Seven parental clones were selected for hy­bridization in Japan in 1996 as part of a shuttlebreeding scheme. All had high starch con­tent between 24% and 30%, and had whiteor yellow flesh. The yield of parental cloneswas about 25 t/ha in Japan. Twelve biparen­tal crosses were made between the parentalclones. Grafting was carried out to promote

progeny was above 32% for all three fami­lies. Dominant genes probably control thistrait. This, together with high hZ, is a veryencouraging result for breeding high DM con­tent.

Shuttle Breeding

Table 1. Families and their parents used to estimate heritability in dry matter content of sweetpotato.

108 Progrom2

Figure 2. Representative frequency distributions of progeny and parent in 18 sweetpotato families used toestimate heritability of dry matter (OM) content: A, OM content of most progenies was lower than thatof the parent; B, parent is in the middle of progeny OM content distribution; (, most of the progenieshad higher OM content than that of the parent. (IP, 1995.

Individual

53.8 ± 0.25464.8± 0.19858.6± 0.19673.4 ± 0.174

Progeny

'---_---01 Parent

22.5 25 27.5 30 32.5 35 37.5

Dry mailer (%)

·w • •• • •i i i i i i i i

8. Family 8894515

Frequency

109

87

6

5

4

3

2

1

a

Family

47.8 ± 0.44473.0 ± 0.40261.2 ± 0.39076.6 ± 0.29612.0 ± 010157.6 ± 0.264

. ·.owww·w

......•..•..•

Iwwo' °11 •i i I i i i i i

A. Family 8894505

C. Family 8894514

Frequency

10 .-------- ----,9

87

65

4

3

21 ~_w..

a .:=1.!!!!=;:=:::::::;:!!=::;::!!=r===:::;~.=;::::=:;

22.5 25 27.5 30 32.5 35 37.5

Dry mailer (%)

22.5 25 27.5 30 32.5 35 37.5

Dry mailer (%)

Frequency

10

9

8

7

65

4

3

2

1

a

Trait

a. Heritability estimates calculated as twice the regressifrn coefficient.

Roots (no./plont)Root weight (g/plant)Dry matter content (%)

Root sizeHarvest indexScab disease

Table 2. Estimates of narrow-sense heritability in sweetpotato'.

velopment of families with the high starchcontent preferred by processors. Shuttlebreeding with japan has allowed us to com­bine seed families with high DM content fromjapan with local parents with other good ag­ronomic characters. Now, the seed familiesresulting from the shuttle breeding programare being distributed to NARS, where they arebeing selected as advanced clones and par­ents for crosses.

Selected Reading

Carey, E.E., E. Chujoy, T.R. Dayal, H.M.Kidanemariam, H.A. Mendoza, and I.G.Mok. 1992. Combating food shortages

and poverty: Sweetpotato breeding forCIP's client countries. CIP Circular19:1-6.

CIP. 1989. Improvement of sweet potato(Ipomoea batatas) in Asia. Report of theworkshop on sweetpotato improvementin Asia held at ICAR, India, October 24­28, 1988. 256 p.

jones, A. 1986. Sweetpotato heritabilityestimates and their use in breeding.HortScience 21 (1 }:14-1 7.

Lonnquist, j.H., W.A. Compton, j.L.Geadel­mann, EA. Loeffel, B. Shank, and A.F.Troyer. 1979. Convergent-divergentselection for area improvement in maize.Crop Sci. 19:602-604.

(IP Program Report 1995-96 109

C. Arbizu\ R. Blas2, M. Holle\ F. Vivanco3, and M. Ghislainl

Advances in the MorphologicalCharacterization of Dca, Ulluco, Mashua,and Arracacha Collections

Morphological characterization and pre­liminary evaluation of ARTC in the Andeanecoregion have continued since the time ofCardenas (Table 2). Almost 6,500 accessionsofoca, ulluco, mashua, arracacha, and achirahave been morphologically characterized orhave undergone preliminary evaluation in thelast 38 yr. Most of the work, however, hasconcentrated only on determining the fre­quency of accessions for each character. Littlehas been done to identify morphotypes orduplicates. One of the main constraints forefficient morphological characterization hasbeen the lack of standard descriptors for eachcrop.

Andean gene banks as of 1995. ClP main­tains 1,356 accessions of ARTC, includingsome of their wild allies (Table 1).

In the present work, morphological char­acterizations of some Peruvian ocas, ullucos,mashuas, and arracachas were formulated inan attempt to answer the following questions:

1. Can a relevant descriptor list be formulatedand tested for each of these crops?

2. Is it possible to identify the best morpho­logical characters within each crop forcharacterization purposes?

3. What is the level of duplication in ocas,ullucos, mashuas, and arracachas main­tained by ClP?

4. Is it feasible to have an efficient collection(minimum of duplicates) of oca, ulluco,mashua, and arracacha in the Andeanecoregion, with the material maintained byCIP?

To answer these questions, three stages ofresearch were followed:

At this stage, a curator has an efficient col­lection with a minimum of duplicates. Con­sequently, the collection is smaller than theoriginal one. Studies on genetic diversity andevaluations such as agronomic characters,nutrition, reaction to biotic and abiotic fac­tors, etc., can be carried out on this kind ofmaterial. Once that has been achieved, a corecollection (basic sample of a germplasm col­lection representing the widest range of di­versity in terms of morphology, geographicalcoverage, and genes) can be established. Sys­tematic activities concerning a germplasmcollection of Andean root and tuber crops(ARTC) are illustrated in Figure 1.

At the beginning, any collection of ARTC isusually large. Morphological characterizationis done to identify morphotypes. Amorphotype is a group of plants showingmorphological similarities, apparently of thesame phenotype, but not necessarily of thesame genetic constitution. Thus, molecularcharacterization can follow to identify geno­types.

ARTC collections have been maintainedin the Andean ecoregion since the pioneerwork of Martin Cardenas and coworkers in1958. The number of accessions maintainedby Andean germplasm banks has increaseddramatically in the last 1°yr as a conse­quence of projects funded by the InternationalBoard for Plant Genetic Resources (IBPGR)in the 1980s and Swiss Development Coop­eration (SOC) since 1993. More than 9,000accessions of ARTC were reported by the

1 ClP, lima, Peru.2 Universidad Nacional Agraria la Molina, lima, Peru.3 Universidad Nacional del Centro del Peru,Huancayo,Peru.

110 Program 2

Morphologicalcharacterization,Morphotypes/

duplicates,Molecular

characterization

Genetic diversityevaluation:

- Agronomic- Nutritional- Stresses- etc.

Figure 1. Strategy for handling collections of Andeanroot and tuber crops.

• Stage 1. Grouping accessions of oca,ulluco, mashua, and arracacha accordingto their morphological similarities to iden­tify morphotypes.

• Stage 2. Recording the highly stable char­acters within each accession of the cropand analyzing the data by cluster analy­sis.

• Stage 3. Using molecular characterizationto identify genotypes of arracacha.

Materials and Methods

In stage 1, 227 accessions of oca, 149 ofulluco, 66 of arracacha, and 64 of mashua,collected from different agroecological zonesof the Peruvian Andes, were grouped visu­ally into morphotypes according to their mor­phological similarities. This grouping wasperformed in Huancayo (3,200 m above sealevel) during three cropping seasons (1993­95). The work on arracacha was conductedin La Molina (240 m) and Huancayo (3,200m) from 1994 to 1996.

The work of stage 2 was performed almostsimultaneously to the visual morphologicalgrouping. We recorded 28 characters forarracacha, 24 for oca, 21 for ulluco, and 18for mashua. For each accession, we recordedqualitative characters, which appear not tobe influenced by environment and are sup­posed to give a better resolution of the groups.Characters of the aboveground parts wererecorded at flowering or in the adult stage,whereas characters of the underground partswere recorded immediately after harvest.Color characters were recorded according tothe Royal Horticultural Society Color Chartof 1995. Data were analyzed by cluster analy­sis.

In stage 3, we attempted molecular char­acterization on the 66 accessions of Peruvianarracachas using randomly amplified poly­morphic DNA (RAPD) markers.

Results and Discussion

Grouping 506 accessions visually accordingto their morphological similarities resulted in

(IP Program Report 1995-96 1 1 1

Totol

482446

9291

6S443358

90

1,356

21

Bra

Institutions'

17

18 I!CA, INIAP, IBTA, INIA, UNA,UNALM,UNSAAC, UNSCH, UNCp, UNTI!CA, INIAp, I.BTA, INIA, UNA,UNALM,UNSAAC, UNSCH, UNCP

16 IICA, INIAP, IBTA, INIA, UNA,UNALM,UNSAAC, UNSCH, UNCp, URPIICA,

4

2

Reports Investigators

(no.)

5

66

Per

1,004

Per = Peru, Bol = Bolivio, Arg = Argentino, Chi = Chile, Bm = Bmzil.

Ecu

Years

Col

Accessions

ARTCjarigin'

o.

author.

b.IICA = Instituto Interomericono de Coopemci6n pam 10 Agricultum, Ecuador; INIAP = Instituto Nacionol de Investigaciones

Agmpecuarios, Ecuador; IBTA = Instituto Boliviano de Tecnologla Agropecuaria, Bolivia; UNT = University ofTurku, Finland;

INIA = Instituto Nacional de Investigadon Agmria, Peru; UNA = Universidad Nacionol del Altiplano, Peru; UNSMC =Universidad Nadonal de San Antonio Abad del Cusco, Peru; UNSCH = Universidad Nacionol de Son Cristobol de Huamango,

Peru; UNCP = Universidod Nocionol del Centro del Peru, Peru; URP = Universidod Ricardo Palma, Peru; UNALM =

Universidod Nocianal Agraria La Molino, Peru; UNC = Universidod Nacionol de Cojomarco, Peru; CIP = Centro Internodonol

de 10 Popa.

Table 2. Morphological characterization or preliminary evaluation of Andean root and tuber crops'. Clp, Peru, 1996.

Table 1. Andean raat and tuber crops maintained by CIP (Dec. 1996).

112 Program 2

the identification of 146 morphotypes of oca,92 of ulluco, 51 of mashua, and 31 ofarracacha. The most important point, how­ever, is that cluster analysis also identified thesame morphotypes within each crop, that is,it confirmed the morphotypes identified byvisual grouping.

Thus, 52% of the Peruvian arracachas,38% ofthe ullucos, 36% ofthe ocas, and 20%of the mashuas maintained by CIP are prob­ably duplicates. An example in which clus­ter analysis confirmed the identification ofmorphotypes is shown in the phenogram ofarracacha (Figure 2). It can be seen that the66 accessions of arracacha were clusteredinto 31 morphotypes and 4 groups at a taxo­nomic distance of about 1.5.

In stage 3, the morphotypes identified instages 1 and 2 were further checked by ap­plying RAPD marker analysis to the 66 ac­cessions of arracacha. Fifteen RAPD primerswere selected out of 31 because of their goodreproducibility and polymorphism. These se­lected RAPD primers generated 75 RAPDmarkers polymorphic with the 66 accessionsof arracacha. The markers resolved the 66accessions of arracachas into 32 genotypesat a similarity coefficient of 0.88.

Only one morphotype did not match withthe molecular clustering; it was split into twogenotypes. The results of morphological (31morphotypes) and molecular characterization(32 genotypes) suggest an almost perfect con­gruence. Therefore, these results demonstratethe value and accuracy of morphologicalcharacterization.

The lack of a perfect congruence could beexplained by the fact that other qual itativeand quantitative characters, not consideredin the cluster analysis, were probably detectedby RAPD. Thus, the genotypes of arracachasidentified by molecular characterization sug­gested that 51 % of the Peruvian arracachasmaintained by ClP could be duplicates.

Table 3 presents the latent roots (varianceon each axis) and their relative contribution

to total variation of the principal componentanalysis. The first 18 principal componentscontributed to about 96% of the total varia­tion of the ocas, 100% of the ullucos, 100%of the mashuas, and 99% of the arracachas.The first three components accounted forabout 37% of the total variation in oca, 47%in ulluco, 49% in mashua, and 51 % inarracacha. The first principal componentappeared more important than the others incontribution to variation in ullu-co andarracacha. No such demarcation was appar­ent between important and unimportant prin­cipal components in oca and mashua.

Table 4 presents the six main charactersthat delineated the accessions of oca, ulluco,mashua, and arracacha into separatemorphotypes and groups in the first three prin­cipal components.

In oca, plant, inflorescence, and tubercharacters such as petiole color, stem color,peduncle and pedicel color, sepal color, andpredominant and secondary tuber flesh colorwere the most important discriminatory char­acters associated with the first componentaxis. But they did not indicate a clear demar­cation between the ones that contributed sub­stantially to the first principal component andthose that did not.

Additionally, the first principal componentaccounted for only 15.7% of the variance(Table 3). The second principal componentis comparable in importance to the first onein that it accounted for 12% of the variance(Table 3). Stem, peduncle, and pedicel color,all of which were important contributors tothe first principal component, were also ma­jor discriminatory characters associated withthe second principal component (Table 4).Other characters associated with the secondprincipal component were predominantabaxial leaflet color, distribution of abaxialsecondary leaflet color, sprout shape, andpetal color. Secondary abaxial leaflet colorand distribution of abaxial secondary leafletcolor are characters that appear to contrib­ute more than sepal color, depth of eyes, sec­ondary tuber flesh color, and distribution of

CIP Program Report 1995-96 113

'" co ~

co 0N ,

QJ

t=uc:CO

iii'5u'E0c:0)(

~~ ~

r-

~ye

'-- r----i~

-

114 Program 2

coco

E~

""o<::CD

...<::0..

Table 3. latent root and percentage of total variation of the first 18 principal component axes for the material studied. Clp, Limo, Peru, 1996.

Principal Oca Ulluco Mashua Arracocha

component

latent Variation Cumulative latent Variation Cumulative latent Variation Cumulative latent Variation Cumulativeroot (%) variation root (no.) variation

(no.) (%) (no.) (%) (no.) (%) (no.) (%)

1 3.76 15.7 15.7 5.27 26.4 26.4 3.40 18.9 24.1 24.1 18.9 6.742 2.88 12.0 27.7 2.45 12.2 38.6 3.09 17.2 15.4 39.5 36.1 4.323 2.33 9.7 37.4 1.77 9.8 47.4 2.38 13.2 11.3 50.8 49.3 3.164 2.20 9.2 46.6 1.67 8.4 55.8 1.62 9.0 8.5 59.3 58.3 2.385 1.73 7.2 53.8 1.56 7.8 63.6 1.49 8.3 6.7 66.0 66.6 1.886 1.33 5.6 59.4 1.20 6.0 69.7 1.21 6.7 6.2 72.2 73.3 1.737 1.25 5.2 64.6 0.96 4.8 74.5 0.94 5.2 4.8 77.0 78.5 1.348 1.07 4.4 69.0 0.88 4.4 78.9 0.85 4.7 4.1 81.1 83.3 1.169 1.02 4.3 73.3 0.74 3.7 82.6 0.72 4.0 3.5 84.6 87.3 0.99

10 0.93 3.9 77.2 0.63 3.2 85.8 0.61 3.4 3.0 87.7 90.7 0.8411 0.75 3.1 80.3 0.61 3.1 88.8 0.42 2.3 2.9 90.5 93.0 0.8012 0.70 2.9 83.2 0.59 3.0 91.8 0.36 2.0 2.1 92.7 95.0 0.6013 0.66 2.7 86.0 0.42 2.1 93.9 0.31 1.7 1.8 94.4 96.7 0.49

~ 14 0.60 2.5 88.5 0.37 1.8 95.7 0.27 1.5 1.1 95.6 98.2 0.32=c

Jl 15 0.58 2.4 90.9 0.32 1.6 97.3 0.13 0.7 1.1 96.7 99.0 0.30a3

16 0.51 2.1 93.0 0.22 1.1 98.4 0.10 0.6 0.9 97.5 99.5 0.24=:-

17 0.38 1.6 94.6 0.16 0.8 99.2 0.06 0.4 0.6 98.2 99.9 0.18~~

~

18 0.30 L3 95.9 0.3 0.1 100.0 0.17~ 0.06 99.6 0.02 0.6 98.8.,..~

~

U1

Table 4. Major characters' associated with the first three principal component axes of 227 accessions of oca, 149 of ulluco, 64 of mashua, and 66 of arracacha. Peru, 1994-96.0-

a3~

(rop Principal component

Oca Petiole calor (0.71Ped. and pedicelSec. tuber fleshStem colorPredom. tuberSepal

UUuco Sec. tuber flt:lch r"l", {(\

Distrib. sec.Distrib. sec. tuber fl,,<:htfll"" rn

Sec. tepal colorPredom. tuber skinTepol base color

Mashua Distrib. sec. stemPredom. stem color (-OJ68)Sec. stem color (00745)Twining (-0.617)Distrib. sec. tuber flesh color (0.527)Mature leaf color (-0.502)

Arracocho Acumen terminolleuflet F0.769)Sec. stor. raot surf. color (0.707)leaflet morgi ncolor (0.687)Sec. propag. flesh color(0.68l)Distrib. propag. flesh color (0.681)Predominant petiole color (0.651)

Principal component 2

Predom. abuxialleaflet calorStem calar (-0.633)Sprout shape (-0.522)Ped. and pedicel color (-0.476)Petal color (-0.463)Distrib. sec. abaxial leaflet color (0.457)Sec. tuber skin color (0.540)Distrib. sec. tuber skinTuber shape (0.513)Tepal base color (0.465)Depth of eyes (-0.441 )Predom. tuber flesh color (0.438)Intensity tuber skin color (-0.729)Sec. tuberflesh color (0.685)Distrib. sec. tuber flesh color (0.681)Predom. tuber flesh color (-0.670)Sec. stem calor (-0.531)Predom. stem color (0.451)Foliage color (-0.743)Sec. abaxial leaflet color (-0.682)Distrib. sec. abaxial leaflet color (-0.670)Sec. stor. root flesh color (0.621)Predom. petiole color (-0.600)Sec. prapag. flesh color (0.548)

Principal component 3

Sec. abaxial leaflet color (-00714)Distrib. set abaxiolleoflet color (-0.70Z)Distrib. sec. tuberflesh color (0.522)Sec. tuber fleshcolor (0.443)Depth of eyes (0.386)Sepal color (-0.382)Plant type (-0.449)leaf shape (-0.431)Foliage color (-0.422)Sec. tuber skin color (-00400)Intensity tuber skin color (-0.399)leofsize (0.355)Predom. tuber skin color (0.839)Sec. tuber skin color (-0.641)Tuber shape (-0.450)Predom. tuber flesh color (0.423)Sec. tuberflesh color(OA21)Distrib. sec. tuber skin color (-0.407)Stor. root shape (-0.613)Predam. propag. surf. color (-0.542)Predom. abaxialleoflet calor (-0.538)Woxon petiole (-0.487)Distrib. sec. petiole calar (-00471)leaflet margin (0.469)

o. Distrib. = distribution, ped. = pedunde, predom. = predominont, propng. = propogule, sec. = secondary, stor. = storage, surf. = surfoce.

secondary tuber flesh color to the third prin­cipal component (Table 4), which accountedfor 9.7% of the variance (Table 3).

For ulluco, tuber and tepal characters con­tribute to the first and second principal com­ponents, whereas plant and tuber charactersare the important delineating characters in thethird component. Tuber characters such asshape, predominant skin color, secondaryskin color, distribution of secondary skincolor, intensity of skin color, predominantflesh color, and secondary flesh color werereported by Finnish scientists to be stablecharacters. A number of Andean investiga­tors have also been using ulluco tuber char­acters along with plant type, foliage color, leafshape, and leaf size to study variation ofulluco in the ecoregion, but only some ofthem considered tepal features.

Mashua. Tuber and plant characters are im­portant determining characters in the first,second, and third principal components inmashua. As in ulluco, the characters identi­fied for mashua in the present work have beenused to study morphological variation of theplant in the Andes, but have not been ana­lyzed or interpreted appropriately.

Arracacha. Leaves, propagules, and stor­age-root characters were shown to be impor­tant determinants of morphotypes inarracacha. Leaf characters were the mosthighly variable in Ecuadorian arracachas.Four leaf characters and 3 storage root char­acters were also used by scientists in Ecua­dor to identify 17 morphotypes of arracacha.Four leaf characters were also used to char­acterize arracachas morphologically in north­ern Peru.

Conclusions

Morphological characterization by groupingaccessions according to their morphologicalsimilarities and by cluster analysis proved tobe accurate and reliable tools to identify

morphotypes in ARTC collections. Molecu­lar characterization in arracacha indicatedthat grouping and cluster analysis gave con­sistent results.

Ou r resu Its suggest that Andean genebanks can use visual grouping alone to iden­tify morphotypes and duplicates in their ARTCcollections at relatively low cost. Clusteranalysis, if it could be afforded, would con­firm grouping results. Molecular characteriza­tion could be used only at an advanced stagefollowing visual grouping and cluster analy­sis.

The grouping patterns of morphotypes inoca, ulluco, mashua, and arracacha showdifferent geographical origin. Accessions fromdifferent agroecological zones of Peru weregrouped by principal components into themorphotypes indicated above. Therefore, itis likely that ethnic groups were responsiblefor disseminating, maintaining, and usingthese crops in the Andean ecoregion.

The use of qualitative morphological char­acters (Table 4) resulted in an excellent reso­lution of the morphotypesfor each crop.These characters could be the basis of de­scriptor lists for oca, ulluco, mashua, andarracacha for morphological characterizationto optimize their handling and use in Andeangene banks.

Selected Reading

Cardenas, M. 1969. Manual de plantasecon6micas de Bolivia. Imprenta Icthus,Cochabamba, Bolivia. 410 p.

Leon, J. 1964. Plantas alimenticias andinas.Boletin Tecnico No.6, InstitutoInteramericano de Ciencias Agricolas,Zona Andina. Lima, Peru. 112 p.

National Research Council. 1989. Lostcrops of the Incas: Little-knownplants of the Andes with promise forworldwide cultivation. National Acad­emy Press, Washington, D.C. 415 p.

(IP Program Report 1995-96 11 7

1 Program Leader, CIP, Lima, Peru.

(IP Program Repor11995-96 119

Pro

resistance to the causal fungus Phytophthorainfestans due to their minor genes of quanti­tative inheritance. Three sets of population B(B1, B2, and B3) are now being tested forimproved LB resistance. Population B1 wasdeveloped through several recombinationcycles of resistance sources of Solanumandigena. Population B2 was obtained fromcrosses between S. andigena and S. tuberosumsources of resistance. Population B3, the mostadvanced source of horizontal resistanceavailable at CIP, was selected from popula­tion A, a previous LB-resistant populationcarrying both quantitative and qualitativetypes of resistance. B3 contai ns mostly S.demissum-derived horizontal resistance im­proved mainly in an S. tuberosum germplasmbackground.

REPORT

DiseaseManagement

PROGRAM

Luis F. Salazar!

The major activities of the Disease Manage­ment Program during 1995-96 included re­search on the control of late bl ight, bacterialwilt, and virus diseases of potato, sweetpotato,and Andean root and tuber crops (ARTC). Theprogram's strategy is to combine basic andapplied research, and this is carried out atheadquarters or in collaboration with scien­tists in developed countries when required.

Late Blight

Late blight (LB) research saw major advancesin the improvement of breeding populations(population B) that carry significant levels ofnon-race-specific and durable (horizontal)

Correlation studies conducted on LBevaluation results from Mexico and Colom­bia have shown that B3 resistance is stableunder those two diverse physical environ­ments and pathogen populations. Wideningadaptation of the B3 population to long daysin Argentina (at 38°S latitude) and China (at400 N and 26°N latitude) is in progress.

Additionally, extreme resistance to potato vi­rus X (PVX) and potato virus Y (PVY) from ClPgenotypes that carry the genes for virus resis­tance in triplex \XXXxYYYy) is being introducedinto population 83. Further improvement of 81and 82 populations continues.

A new group of LB-resistant materials(population C) is at the prebreeding stage ofdevelopment at OP-Lima. This breeding stocknow comprises 186 diploid potato hybridsthat carry factors of resistance to foliage blightfrom 13 species of wi Id and native cu Itivatedpotato. The prebreeding effort aims atintrogressing durable resistance to late blightinto population C breeding stock. PopulationC will be a core collection of a wide range ofdiverse resistances in ready-to-use potatobreeding clones.

CIP's major emphasis in LB research wasuntil recently on building resistance to thefungus for use by NARS in integrated diseasemanagement (lDM). With the Global Initia­tive on Late Blight (GILB) now in operation,the IDM approach will receive high priority.Research on and application of other IDMcomponents such as the use of appropriateagronomic practices, use of clean seed, orbiological control will be encouraged.

Bacterial Wilt

Research on controlling bacterial wilt (BW)of potato, caused by Ralstonia (Pseudomo­nas) solanacearum, was particularly ad­dressed to IDM components. The use of cleanseed tubers, identified by the enzyme-linkedimmunosorbent assay, has proved an effec­tive BW control measure in Indonesia. Be­cause it has proven difficult to build geneticresistance to BW into acceptable genotypes,we reduced efforts on this approach. Remain-

120 Progrom 3

ing activities conducted in collaboration withsome national agricultural research systems(NARS) were mainly directed to evaluatingBW resistance of promising genetic materi­als generated in CIP. Some BW-resistant po­tato clones, also carrying acceptable levelsof resistance to LB, have been selected in In­donesia and China.

In other studies on IDM components, pre­liminary experiments in China suggestedgood possibilities of using bacterial suspen­sions of two strains of Bacillus for the bio­logical control of 8W. Farmer participatoryexperiments in Uganda showed that im­proved IDM packages that include a resis­tant cu Itivar, clean seed, adequate planti ngspace, roguing of volunteer potatoes, sanita­tion, and minimum cultivation increasedyields up to 75%.

Virus Diseases

New virus diseases were found to threatenpotato production in some countries. Amongthese, yellow vein in Ecuador and Colombia,Saq'o in Bolivia, deforming mosaic in Brazil,and rough dwarf or potato virus P (PVP) inArgentina and Brazil deserve mention. Yel­low vein is by far the most important becauseof its effect on yield. Although the virus hasnot yet been identified, evidence indicates itis a virus with unusual characteristics. Theputative virus is apparently prevalent in weedsand other crops and moves into the potatocrop through its wh itefly vector Trialeurodesvaporariorum. Studies on Saq'o suggested theinvolvement of an unusual strain of potatoleafroll virus (PLRV). Other yet-unidentifiedphytoplasma-like microorganisms also appearto be implicated in the Saq'o disease. Theother viruses mentioned are still under studyin collaboration with scientists in Brazil andArgentina.

Deforming mosaic from Brazil appearsdifferent from that reported years ago fromArgentina. It is probably a geminivirus,whereas rough dwarf in Argentina or PVP inBrazil is a carlavirus resembling the well­known potato virus S (PVS), which causessevere symptomatology in potato.

Phytoplasmas, formerly known as myco­plasmas, have also spread in recent years.They have caused severe damage, particu­larly to seed tuber production in Peru andMexico. Because of the importance of thesediseases, we have diverted limited funds tostudy these pathogens. Our major activitiesare directed toward developing sensitive de­tection technology for all these diseases.

Because pathogens usually interact in na­ture in a positive or negative manner, we arestudying these plant-pathogen interactions indetail. An example of a negative interactionhaving epidemiological significance is trans­mission of the potato spindle tuber viroid(PSTVd) by aphids when PSTVd and PLRV co­infect potato plants. Molecular experimentsshowed the transmission to occur throughencapsidation of the small PSTVd moleculein particles of the aphid-transmitted PLRV.Spread of the viroid through encapsidationhas occurred in potato crops in China.

An important interaction among patho­gens of the positive type is the significant re­duction in the rate of P infestans (LB) devel­opment in potato plants infected with PYX,PVY, or PVS. Virus-infected plants showedreduced penetration of zoospores and re­duced sporulation of the fungus, thus reduc­ing the number and size of lesions. With vi­ruses such as PVS that have no significanteffect on yield, this interaction will be furtherexplored as a component of IDM.

Molecular approaches are seen as an im­portant complement to traditional breedingfor resistance to virus diseases. In collabora­tion with the Sainsbury Laboratory in theUnited Kingdom, molecular characterizationof virus resistance genes in potato was con­tinued. For the Rx gene (conferring extremeresistance to PYX), a BAC (bacterial artificialchromosome) library for the cloning of RYadg

has already been developed and isolation ofthe Rx locus is under way. For Ry (conferringextreme resistance to PVY), molecular char­acterization of the RYsto locus is in progress atSainsbury.

Virus-free planting materials were evalu­ated for the control of sweetpotato virus dis­eases. In China, virus-free planting materialsoutyielded farmers' seed by at least a factorof 2. Efficient virus detection technology isessential to produce virus-free planting ma­terials. We are continuing virus identificationand characterization studies. Several newlyrecorded viruses have been characterized.Studies on sweetpotato virus disease (SPVD)suggested that one of the two components,the whitefly-borne c1osterovirus (WBV), var­ies in its interaction with sweetpotato feath­ery mottle virus (SPFMV), depending on theregion where SPVD occurs.

Our previous hypothesis that control ofSPFMV was sufficient to control SPVD wasnot borne out in Uganda, where cultivarshighly resistant to SPFMV degenerate withSPVD. Apparently WBV breaks the resistanceto SPFMV and SPVD develops. Our new strat­egy calls for developing WBV resistance. Ifhost-mediated resistance cannot be found inCIP sweetpotato germplasm or elsewhere,development of transgenic resistance will beattempted using virus-derived genes.

Andean Root and Tuber Crops

Research on ARTC diseases allowed us todevelop a manual on ARTC diseases to bepublished soon. In addition to ARTC-specificviruses, there are some important potato vi­ruses that also attack ARTC. From an epide­miological point of view, these findings areimportant for developing viral control mea­sures in both potato and ARTC.

(IP Program Report 1995-96 121

J.A. Landeo\ M. Gastelo\ G. Forbes\ J.L Zapata2, and EJ. Flores3

Developing Horizontal Resistance tolate Blight in Potato

and effective gene frequency upgrading moredifficult.

Starting in 1990, following a LB strategyreview at OP, a new breeding strategy wasdesigned to upgrade horizontal resistance inthe absence of R genes (population B). Theabsence of R genes, or removing their inter­ference in assessing true horizontal resistance,has already resulted in a more efficient breed­ing scheme. We are witnessing an increasein gene frequencies and higher levels of re­sistance along with traits of agronomic value.

The new strategy includes the develop­ment of th ree independent subpopu lations tobroaden the genetic diversity for resistanceand maximize the use of horizontal resistancefrom cultivated germplasm. The first popula­tion is derived from a wide sample of nativecultivars from S. tuberosum subsp. andigena(B 1). The second is derived from the samesource of S. andigena, but crossed only onceto R-gene-free S. tuberosum cultivars to im­prove some agronomic traits lacking in S.tuberosum subsp. andigena (B2). The third,which is the most advanced agronomically,is derived from population A (B3).

Progress in developing population B3 isreported here since this breeding popula­tion receives major emphasis in OP's re­search program. It has many desirable ag­ronomic characters and good levels of hori­zontal resistance obtained from sources ofpopulation A.

Quantifying Horizontal Resistance in 83

Materials and methodsThe experimental material included

progenies obtained following a line x tester

During the early 1980s, CIP researchersbegan to exploit their own breeding popu­lation assembled from Solanum demissum­derived advanced sources of resistance in­troduced into S. tuberosum subsp. tuberosum,Neotuberosum, and S. tuberosum subsp.andigena germplasm, and four-way hybridsbetween S. acaule, S. bulbocastanum, S.phureja, and S. tuberosum (ABPTs). Througha testing strategy that included Peru, Colom­bia, and Mexico, by the end of the decadesome 300 clones with various levels ofhorizontal resistance to LB and good agro­nomic attributes, including quality, wereselected. They were made available to clientcountries on all continents.

Late blight (LB) disease in potato, caused byPhytophthora infestans, is one of the majordiseases researched at OP since its founding.It is a cause of serious potato productionlosses, particularly in less developed coun­tries around the world. CIP scientists have al­ways believed that host resistance could playan important role in the management of thedisease, particularly in OP's client countries.Therefore, breeding for resistance has been amajor endeavor since its early days.

From 1990 to 1996, more than 30 LB-re­sistant varieties were released in 15 countries(Table 1). A particular feature of this breedingpopu lation is that horizontal resistance wasimproved in the presence of undesired, un­known major (R) genes for vertical resistance(population A). Their presence, rather thancontributing to the overall resistance, madethe recognition of true horizontal resistance

1 ClP, Lima, Peru.2 Corporaci6n Regional dellnstituto Colombiano

Agropecuario (CORPOICA), Rionegro, Colombia.3 Instituto Nacional de Investigaciones Forestales y

Agropecuarias (INIFAP), Toluca, Mexico.

122 Progrom 3

Nurula

(IP Progrom Report 1995-96 123

Table 2. Estimates of heritability for horizontal resistance to late blight and total tuber yield in a sample of clonesfree of Rgenes from population 83.

Peru

0.430.26

Mexico

0.410.24

Colombia

The values may be somewhat inflated,however, because of the contribution of thesource genotype x environment interaction,which was not isolated from the main sourceof genetic variation. In this sampled popula­tion, additive genetic variances have magni­tudes significant enough to ensure progressin breeding and selection for outstanding LB­resistant clones with attributes to becomevarieties.

Materials and methodsThe sample tested in 1995 was composed

of 60 fami Iies from intercrosses between thefirst lot of R-gene-free parents (47 clones) andcontained approximately 6,000 individuals.The sample tested in 1996 included another

60 families with approximately 8,000 indi­viduals. They were both tested for LB resis­tance in the field at Rfonegro and Toluca, thesamples being exact duplicates at each site.Families in the 1995 sample were not repli­cated, whereas families in the 1996 samplewere replicated and arranged in the field inan incomplete simple lattice design. Sixweekly readings on percentage of foliage in­fection were taken for every individual dur­ing the season at both sites in 1995; four

Correlation Studies for HorizontalResistance to Late Blight in B3

In the process of continuing improvement ofpopulation B3 at CIP, correlation studies forLB resistance were conducted in samples ofthis population for two consecutive years(1995 and 1996) at two LB endemic sites withcontrasting ecologies and pathogen popula­tions. The sites chosen were Toluca, Mexico,and Rionegro, Colombia.

0.560.52

0.710.25

Site 1 Site 2

Trait

Late blight resistance

Total tuber yield

mating design of a sample of R-gene-freeclones.

Three clones were used as male testers.Quarantine-produced tuber families of theprogenies obtained were arranged in incom­plete simple lattice designs with two replica­tions and sent for testing under local LB epi­demics to two sites in Cajamarca, Peru, andone site each in Rionegro, Colombia, andToluca, Mexico, during the growing season.Percentage of leaf area infected was recordedfor 6 consecutive weeks and average appar­ent infection rates per fami Iy were calcu latedto quantify horizontal resistance.

Likewise, family average total tuber weightper plant was used for yield. Analysis of vari­ance was determined for the Iine x tester mat­ing design, and the source of variance due toclones was used to calculate the general com­bining ability variance, which is associatedwith the additive portion of the total geneticvariance. At each of the three sites, narrow­sense heritabi Iity for resistance and yield wasestimated following standard procedures.Combined analyses were not attempted be­cause different line samples and testers wereused for Peru, Colombia, and Mexico.

ResultsThe mean squares for clones at all sites

were highly significant for resistance andyield. Combining ability variances, calculatedfrom the sources of variation of the clones,and heritabilities ranged from 0.41 to 0.71for resistance and from 0.24 to 0.51 for yield(Table 2). These estimates indicate that bothcharacters are at mid to high levels for a quan­titative trait.

124 Progrom 3

weekly readings were taken in 1996. The areaunder the disease progress curve (AUDPC)was calculated and used as a parameter forresistance. Averages of AUDPC per familywere used to rank families at both sites andSpearman's rank correlation was performed.

ResultsThe combined analysis of variance for the

1996 sample (CV = 17%) indicated that thefamily source of variation was highly signifi­cant whereas the environment source of varia­tion was not. However, the family x environ­ment interaction was also significant. Thisindicates that family performance for resis­tance varies significantly and that some mayhave performed differentially at each of thetwo sites. After calculating the correlationcoefficient, however, which was also signifi­cant and quite high (r =0.79 for 1995 and r =0.82 for 1996), it seems that there is a linearassociation between resistance performancesof families at the two sites (Figure 1).

The coefficients of determination (R2 =0.61for 1995 and R2 = 0.66 for 1996) indicate thatthe linear association between the family per­formances at these two sites can be explainedby about 60%. That leads us to conclude atthis point that the expression of horizontal re­sistance to LB present in this improved sourceis rather stable and was not affected signifi­cantly by divergent environments. The geno­type x environment interaction, althoughpresent, may not be as high as earlier sus­pected according to our results.

On the basis of these results, whereby test­ing was conducted under LB disease pressureof two endemic locations, we can concludethat horizontal resistance, under improvementin the B3 population, is in fact expressed ef­fectively in a wide range of the pathogen andunder contrasting environments. Toluca isnoted for containing the most diverse patho-

gen populations of P. infestans, including bothasexual and sexual stages of the fungus; inRionegro the disease pressure is more uni­form and higher than in Toluca throughoutthe season, but less diverse. Thus, either sitecan be used to effectively test and select forstable horizontal resistance to LB.

Conclusions

Classical breeding approaches applied topopulation B as a continuation of populationA improvement have been quite efficient inupgrading gene frequencies for horizontal re­sistance to LB, together with important agro­nomic traits. B3, the most advanced sourceof resistance, is at the stage of being readilyused by breeding programs. It is also be:ngfurther improved at CIP through recurrentselection with progeny testing.

Further improvement is foreseen inachieving higher levels of stable resistance,broadening its genetic diversity, increasingadaptability to a wider range of daylengths,and gradual combination with other impor­tant disease and pest resistance or tolerance.Marker-assisted selection, as it becomes ap­plicable and practical, is contemplated to fur­ther increase accuracy and efficiency in theoverall process of selection for horizontal re­sistance to LB.

Selected Reading

ClP (I nternational Potato Center). 1973-74.Program planning conferences. Report ofthe program planning conferences heldat CIP during 1973 and 1974. Lima,Peru. 384 p.

CIP (International Potato Center). 1989.Fungal diseases of the potato. Reportof the planning conference on fungaldiseases of the potato held at CIP, Sep­tember 21-25,1987. Lima, Peru. 216 p.

(IP Program Report 1995-96 125

160014001200

r:::: 0.79r2 :::: 0.61

... ~.....• •••• •

1000800600400200o I----+-~~--_+-~-_+_.--.-.+_.--.-+_---~..-__+

o

AUDPC (Colombia)

800

200

400

600

A

AUDPC (Mexico)

2000

1800 • ••• .+ I1600 4' •1400 •• •.. • •1200 •• <Ijp}

+1000 • +

•800 +

600

•400 • r"" 0.82r2 ",,0.66200

00 200 400 600 800 1000 1200 1400 1600

AUDPC (Colombia)

B

AUDPC (Mexico)

1000

1200

1400

Figure 1. Simple correlation of AUDPC from Colombia and Mexico, 1995 (A) and 1996 (B).

126 Progrom3

B. Trognitz, M. Eslava, L. Portal, and P. Ramon!

Resistance to Late Blight from DiverseWild Sources

Materials and Methods

(IP Progrom Report 1995-96 127

A polycyclic blight epidemic developswithin 2 wk. Three readings of the percent­age of foliage area affected are taken at 2­day intervals, starting when the susceptiblecheck, Yungay, has an average of 30% foli­age area affected. The average of the threereadings over the two repetitions is then takenas a measure of the degree of resistance of agenotype. Data are analyzed by ANOYA foreach group of clones assayed at a time. In

Samples of botanical seeds of several acces­sions of diploid wild and native cultivated po­tatoes were grown. The accessions had beenselected, based on their known or suspectedresistance, from collections held at ClP; thePotato Introduction Station, Sturgeon Bay,Wisconsin, USA; and the potato gene bankat Gross Lusewitz, Germany. To detect pos­sible race-specific interactions, detached leaf­lets were placed in petri dishes and inocu­lated with isolates of P. infestans of differentvirulences.

A quick and reliable test of foliage resis­tance under controlled conditions in thegreenhouse was developed at ClP-Lima. Forthis test, stems with fully developed foliageare taken from adult plants and placed in milkbottles in a screenhouse equipped with mistirrigation to produce high air humidity andfavorable conditions for blight development.A randomized two-block design is used, inwhich the experimental unit is a sample ofthree stems of a given genotype in a singlebottle. The foliage is inoculated once aftersunset with a suspension of 15,000 sporan­gia/ml of a virulent isolate representing a po­tato (S. tuberosum) race of P. infestans of alineage common in the Andean region ofPeru, Ecuador, and Colombia.

To more systematically exploit the largecollections of wild potatoes maintained at ClPand in other potato gene banks, we investi­gated several lesser-known and underusedpotential sources of resistance to LB. We in­cluded South American wild species in theexperiment because it was believed until onlyrecently that these species would not possessmajor (R) genes for race-specific resistanceto LB. The South American species, unlikeseveral native species of Mexico, have beenexposed to P. infestans relatively recently intheir evolutionary history. But evidence isgrowing that R genes, each one of them con­ferring resistance against only a few strainsof the pathogen, also occur in potatoes in­digenous to South America. Therefore, wemust also test our hybrids for the presence ofR genes.

Because many improvement programs arein developed countries with moderate cli­mates, the new hybrid potato stocks devel­oped there may be of limited use in the tropi­cal and subtropical environments of devel­oping countries.

1 CIP, Lima, Peru.

Widening the gene pool of potato (Solanumtuberosum) to enhance the crop's resistancethrough the use of wi Id relatives has becomea routine strategy. This is especially true forresistance to Phytophthora infestans, thecausal agent of late blight (LB), for which re­sistance of the common potato is limited.Several wild relatives of potato have beenused, but efforts are concentrated on only afew sources of resistance. Some of them havebeen used repeatedly over the past 50 years.

this way, successful identification of LB resis­tance is possible throughout the winter pe­riod in Lima, from June to November.

Besides Yungay, four other checks with dif­ferent levels of resistance are always includedin the assay. Although the overall degree ofinfection varies between individual inocula­tion dates, the relative differences in resis­tance levels expressed by the checks arehighly reproducible, with a correlation coef­ficient of r=0.70-0.99 between pairs of indi­vidual inoculation cycles. The average areaof blighted foliage of the checks observed infive inoculation cycles in 1996 was (fromhighest to lowest level of resistance): ClPbreeding clone 381381.26 (released asIngabire in eastern Africa), 17.1%; CanchanINIAA (released in Peru), 21.2%; Atzimba(Mexican variety), 34.6%; Yungay (Peru),48.5%; and Pimpernel (Netherlands), 50.6%.The ranking and the relative differences be­tween the varieties' scores observed in thisdetached foliage test are the same as thoseobserved in field experiments. Therefore, ourresistance test using detached foliage is re­producible and gives a good estimate of thelevel of field resistance of the genotypestested.

Detached leaflet assays revealed that clone381381.26 does not sporulate after inocula­tion with the isolate used for the screenhouseinoculations. This indicates that 381381.26possesses specific (R-gene-mediated) resis­tance to this isolate. We conclude thereforethat R gene resistance is equivalent to read­ings of an average of 17% affected foliagearea in the trial used. Therefore, the directselection of highly resistant genotypes that donot express R gene resistance, by relying onthe phenotype of a single clone in thescreenhouse or field, appears to be impos­sible.

Selected LB-resistant clones of accessionsof diploid wild species were crossed withpotato dihaploids. The resulting hybrids havealso been subjected to a series of tests for thelevel and race-specific or -nonspecific resis­tance inherent in them, as described above.

128 Progrom 3

Results

One hundred and three individuals of 28single-cross progenies were selected in Lima,and 70 individuals of 15 progenies in Quito,for their high levels of foliage resistance toLB. These selected hybrids include the resis­tances of 16 accessions of 13 wild and na­tive cultivated Solanum species (Table 1).These hybrids are all diploid, and most ofthem produce unreduced pollen. This willallow them to be used in meiotictetraploidization through pollinations of tet­raploid varieties and breeding clones. Forselected clones, the mechanism of formationof unreduced pollen will be elucidatedthrough cytological means.

In addition, we used 13 clones with highlevels of quantitative LB resistance, wh ichwere selected from a set of diploid hybrids ofthe former bacterial wilt breeding program atClP, in crosses with potato varieties to obtaintetraploid hybrids. The tetraploidized geno­types were propagated c10nally and tested forLB resistance. We have identified severalhighly LB-resistant, early to medium-latematuring genotypes expressing agronomicallyacceptable tuber characteristics.

Segregation of resistance in individual dip­loid hybrid populations was analyzed usingthe data of both the detached-leaflet and de­tached-foliage assays. In the inoculations ofdetached leaflets, sporulation was taken as acriterion for compatibility with the isolateused. Several hybrid populations screenedexpressed sporulation on leaflets of all geno­types with four isolates used. One isolate hadno aviru lence genes; the others possesseddifferent combinations of avirulence genesinteracting with the 11 known R genes of S.demissum. For a summary, see Table 1.

Segregation of the level of resistance in re­lation to the resistant check in a progeny ofth is race-non-specific reaction type is givenin Figure 1. The segregation in the progenyof the cross of CIP dihaploid PS5 x S.ambosinum, OCH 11865, clone 24, isunimodal and fits a normal distribution. Aprogeny obtained from a self of dihaploid PS5also showed a pattern of segregation that fit a

CIP Program Report 1995-96 129

Race-specific

reaction observed

Yes? °NoYes

NaYes?Yes?

NoYes

NoNoNoNoYes?Yes?

Yes

No

I­S

MediumMediumHigh

MediumMediumMediumMediumHigh

HighHigh

High

HighHighHigh

MediumMedium

Resistance

level

4

2

21

111

1

1

1

1

2122

1

1

3

lates used, suggesting that PS5 does not pos­sess race-specific resistance alleles for any ofthese isolates.

2

Individuals (no.)8

6

4

2

o

Accession code,.{oUedor Resistont

number plants used (no.)

CIP 761070, OCH 11297

OCH 11865

CI Pselection, KV Ro man

761164, OS 11007588, OCH 13345

OP 761582, OCH 13325

CIP 761028, O/S 11855

PI 500041

INIAP, Ecuador, BOM 540

INIAP, Ecuador, CHS 625

PI 320376

PI 225678

C!P 761072, 0/5 11615

CIP761243, OCH 11630

OP 761691, OCH 13640

1059

a. The question mark indicates that race-specific interactions observed in preliminary experiments must be confirmed insubsequent studies. Aprecondition is the identification of differential isolates for these materials.

Level of resistance (1 = level of the resistant check, clone 381381.26; 5 = low level)

piume

aerDglossumambosinumberthaultiialbomoziiehiquidenumehamataphifumlaxissimummicradontumphurejaphureja

Figure 1. Histogram showing the segregation of resistance to late blight in a progeny of 18 individuals of thecross of dihaploid PS5 x S. ambosinum, OCH 11865, clone 24.

Table 1. Accessions of wild and cultivated potato containing high levels of resistance to late blight that are usedfor introgressian of resistance into potato.

normal distribution in the screen house test.All individuals expressed sporulation afterinoculation of detached leaflets with all iso-

130 Progrom 3

7654

Of the species contributing race-non­specific resistance, comparably high levelsof resistance of hybrids were obtained onlywith S. phureja. This native cultivatedpotato reacts to infection by droppingdiseased leaves through abscission at thepetiole base. As such it represents aresistance phenotype different from S.tuberosum, in which diseased fol iage

Segregation into distinct resistanceclasses was observed in progenies carryingthe resistances of the South Americanspecies S. acroglo55um, S. berthaultii, S.chiquidenum, S. chomatophilum, S.microdontum, S. paucissectum, and S.santolallae (Table 1). Hybrids into whichthe race-specific resistances of these SouthAmerican species were incorporatedexpressed intermediate to high levels ofresistance in the screen house test.

contributing a distinct level of foliageresistance, can also be envisaged.

Further analysis of segregation in F2 orbackcross populations derived from this S.berthaultii hybrid progeny is necessary toelucidate the number of putative R genesinvolved and their type of action. It ispossible that these genes contribute adurable, residual effect to the resistance,even when they are broken down.

32

Level of resistance (1 =level of the resistant check,clone 381381.26; 7 =low level)

The same resistant individuals did notsporulate after inoculations of leaflets withthree individual isolates. Some of thesusceptible individuals (Figure 2, resistancelevels 3-7) were tested in the detached­leaflet assay. All showed sporulation withat least two of the three isolates used. Theobserved segregation into resistant andsusceptible phenotypes perfectly fits a 1:1ratio indicative of a single gene. However,the frequency distribution shown in Figure2 is not bimodal, as would be expected forsegregation of a single factor, but isunimodal and skewed. Therefore, a modelof segregation of several dominant, race­specific resistance genes, each one

Individuals (no.)

20.------------------------------.

15+-----­

10+-----

5+-----

o

Figure 2. Histogram showing the segregation of resistance to late blight in a progeny of 44 individuals af thecross of dihaploid PS5 xS. berthaultii, clone 1.

Several hybrid progenies, however, hada percentage of individuals that reacted withhypersensitivity or not at all to theinoculations of detached leaflets with aparticular isolate. These populations alsoexpressed segregation of the degree ofresistance, as measured in the foliage assayin the screenhouse. An example is theprogeny of the cross of dihaploid PS5 x S.berthaultii, clone 1 (provided by K.V.Raman, ClP, 1991), shown in Figure 2. Of44 individuals tested in the screenhouse,22 either had no infection or up to twicethe affected foliage of the resistant check(clone 381381.26), resistance levels 1 and2 in Figure 2.

remains on the plant. Abscission of infectedleaves was observed in the field and ondetached foliage tested in the screenhouse.This resistance type is also expressed by 5.urubambae, and it is transmitted to thehybrids.

Conclusions

The total of 186 selected diploid hybridsdescribed above represents the basic pool ofLB resistance genes of a wide range of geneticresources. We are currently using this cohortof selected clones to develop tetraploids ininterploidy crosses with advanced potatobreeding clones. The tetraploid hybrids wi IIthen complement a set of progenitors-CiP'sgroup C or population C-that carry the newresistances. We envisage group C as a corecollection of a wide range of diverseresistances, ina ready-to-use form of potatoclones that are acceptable to breedersbecause of their improved agronomiccharacters.

The hybrids wi II also be used for studiesof the genetics and inheritance of resistanceto LB. Segregating populations for geneticmapping of resistance factors will be obtainedthrough F2 or backcrosses for efficient intro­gression of these factors into potato breeding

stocks and to isolate candidate resistancegenes for plant molecular transformation.

Despite our observation that one-half ofthe wild potato species investigated possessrace-specific resistance conferred by R genes,we will explore furtherthe feasibility of breed­ing using R-gene-free materials. Nevertheless,wild species may harbor stable R genes thatcould provide durable protection against LB.We will survey the genetic material studiedin th is paper for its resistance genes throughinoculations with Phytophthora isolates thatrepresent a wide range of virulences andhosts.

Selected Reading

Toxopeus, H.J. 1964. Treasure-digging forblight resistance in potatoes. Euphytica13:206-222.

Ross, H. 1966. The use of wild Solanumspecies in German potato breeding ofthe past and today. Am. Potato J. 43:63-80.

Ross, H. 1986. Potato breeding: Problemsand perspectives. Advances in PlantBreeding, 13. Paul Parey, Berlin andHamburg. 132 p.

CIP Program Reporf 1995-96 131

B. Trognitz, M. Ghislain, G. Forbes, P. Oyarzun, M. Eslava,R. Herrera, L. Portal, P. Ramon, and G. Chacon1

Evaluation of Late Blight Resistance inPopulations of Diploid Potato Hybrids forGenetic Mapping

Population VP

esized that potato relatives indigenous toSouth America would not possess R genes;all resistance expressed by them would bepolygenic and quantitative. However, evi­dence is emerging that many South Ameri­can species also employ R genes. Therefore,it is desirable to test every potential source ofresistance for the occurrence of race-specificresistance genes, and it is reasonable to ex­pect that additional Rgenes are yet to be iden­tified.

Two sources of resistance to LB wereinvestigated in two segregating populationsof diploid potato hybrids. One population wasa cross between highly resistant S.verrucosum and susceptible S. phureja,designated population YP. The other was across between resistant S. phureja and asusceptible S. tuberosum dihaploid,designated population PD. The POpopulation was selected for the study fromnine diploid hybrid populations carrying highlevels of resistance to LB.

This investigation had two objectives. Onewas to characterize the level of resistance ofevery individual of the two populations as aprecondition for genetic mapping. Thesecond was to test the populations for theoccurrence and segregation of race-specificR genes.

This population comprises 102 individuals,all of them late-maturing under the shortdaylength of Cajamarca, Peru. All genotypesform small, pear-shaped tubers of creamy-

Twelve R genes for resistance to LB havebeen identified. Differential potato clones todistinguish 11 of them are available. These11 R genes originated in. Mexican wild S.demissum, and this and other Central Ameri­can potato relatives are assumed to have de­veloped many more R genes. The Mexicanwild potato S. verrucosum is reported to pos­sess high levels of quantitative resistance be­sides R gene-mediated resistance. The suc­cessful use in resistance breeding of this andother wild and native cultivated potatoestherefore depends on knowledge of the oc­currence and identity of R genes.

1 CIP, Lima, Peru.

To increase the durability of resistance toLB, researchers seek forms of resistance thatare effective against a broad range of patho­genic strains of Phytophthora infestans. Poly­genic, additive resistance is the most promis­ing. This resistance can be masked by mono­genic, race-specific major (R) gene-mediatedresistance when no races compatible withsuch an R gene are available. This is mostimportant when the identity of R genes is notknown.

Wild and cultivated relatives of the potato(Solanum spp.) carry valuable resistances tolate bl ight (LB) that, when introgressed intopotato, are thought to considerably reducethe crop's vulnerability to this devastating dis­ease.

One strategy to avoid interference with Rgene resistance could be to choose genotypeswithout R genes. Previously, it was hypoth-

132 Program 3

(IP Progrom Repolt 1995-96 133

More737 824 911

Ninety-nine individuals were inoculatedwith five isolates of P. infestans, each possess­ing a different level of virulence (Table 1). Theexperimental unit was a petri dish contain­ing four lateral leaflets from different fullydeveloped top leaves of one to three plantsin bud or flowering. The plants were grownin pots in a greenhouse at Lima during thewinter of 1995. Humidity was maintained byadding a sheet of moist filter paper to eachpetri dish. Readings of sporulation and areaaffected were taken 5 d after inoculation, orwhen the controls showed the expectedsymptoms. Tests were repeated one to three

Race-specific resistance of VPWe performed detached-leaflet tests to

analyze the segregation of the discrete traitresistance to sporulation. The phenotype ofR gene resistance in this test is a hypersensi­tive response of leaf tissue. Sometimes nosymptoms or only weak infection is observed.Sporulation occurs rarely. We classified in­dividuals as susceptible or resistant based onthis variabi lity of the expression of resistance.individuals on which P. infestans sporulatedwere classified as susceptible; those that didnot allow the pathogen to sporulate in any ofthe repetitions were considered resistant.

AUDPC value

213 300 387 475 562 649125

40

30 -------

50

Figure 1. Population VP: frequency distribution of AUDP( measured on 99 individuals in 3-yr field trial,(ajamarco, Peru.

Individuals (no.)

Vp field resistanceVP individuals were evaluated for resis­

tance in the field at Cajamarca, Peru, underhigh infection pressure, in 1994, 1995, and1996. The parents did not grow in the fieldor were not available and could not be in­cluded in the experiment. A randomizedblock design was used and the area underthe disease progress curve (AUDPC) was cal­culated from weekly readings of the percent­age of diseased fol iage in plots of 10 plantsper clone and block. The VP population hada high average field resistance (progeny mean,AUDPC=303, range 168-999; resistant stan­dard Perricholi, AUDPC=410; susceptiblestandard Yungay, AUDPC=997). its fre­quency distribution (Figure 1) deviated fromthe desired normal distribution typical for aquantitative trait.

white flesh that sprout early. The entire popu­lation expresses a cytoplasmic male sterility(eMS) phenotype that is known as ecl ipse ste­rility. Although preliminary intrapopulationcrosses were unsuccessful, it may be possibleto use the VP individuals as females in crosseswith pollen-fertile genotypes because femalefertility is not affected by CMS.

1:31:31:1

1:1.751:2.31:5.60:1

0:1

Segregation Segregation

observed expected for single­

gene resistance

84

progenies

(no.)

Susceptible

After 3 yr of resistance testing in thefield, the AU DPC means of genotypes dif­fering in their resistance to 0, 1, 2, or 3isolates were compared by a series of t­tests (Figure 2). None of the means couldbe clearly separated. But the tendency ofsmaller AUDPC values to be associatedwith a higher number of isolate-specificresistances indicates a small but favorableresidual effect of these factors on the ex­pression of resistance in the field. Also,the mean AUDPC value (meanAUDPC=280) of all 36 individuals that were

A host-pathogen interaction scheme is pre­sented in Table 2. The eight resistance pat­terns observed in the population indicate thatthe virulences of the isolates 275, P2, and 50are different from each other. At least threefactors of race-specific resistance must beassumed to segregate independently in theVP population. Isolates 8 and 275 share theavr1 gene for virulence on potato (5.demissum) gene R1 (Table 1), yet they havediffering patterns of compatibility with the VPindividuals. That result indicates that isolate8 possesses more virulences either to R gene8 (for which no differential was available) orto some other unknown resistance genes.

backcrosses to the susceptible 5. phureja par­ent.

times and the accuracy of a test result wasestablished by comparing it with the reactionof resistant and susceptible control cultivars.

progenies

(no.)

The inoculum was applied with a spraybottle. The inoculum concentration was5,000-15,000 sporangia/ml washed frommycelium grown on tuber slices. This highinoculum concentration was chosen to en­sure that all susceptible individuals becameinfected.

Resistant

Table 1. Inoculations of detached leaflets of VP individuals with 5 isolates of Phytophthora infestans.

Of 99 plants tested, none was resistant toisolates 8 and 260. With the remaining threeraces, segregation into resistants andsusceptibles was obtained (Table 1). The ra­tios of resistantsusceptible individuals ob­tained with either race significantly (P<O.OOl)diverge from ratios expected for a model ofsingle dominant genes of resistance. Morefeasible models were the complementary ac­tion of two or more resistance genes, or a re­sistance gene and a suppressor gene. In doz­ens of inoculations done over 5 yr, our con­trols carrying R genes always responded re­sistant to the respective aviru lent isolates.None developed sporulating mycelium. Pos­sibly the resistance genes of 5. verrucosumbreak down under particular environments,thus resulting in an excess of susceptibles.Segregation results must be confirmed by test­ing the V and P parents and by analyzing

134 Program 3

CIP Progrom Report 1995-96 135

sources of resistance to LB was screened atClP-Quito, in 1992 and 1993. Resistantclonal selections were crossed with potatodihaploids to produce diploid hybrid prog­enies. A sample of nine early-maturing prog­enies was subjected to a 2-yr field trial forresistance. The cross CHS-625 x PS-3 per­formed best of all progenies. Its progeny meanof resistance (AUDPC=152, 50 individuals)

AUDPC 350

300 .

250

200

150

100

50

0Individuals (no.) 43 37 13 6

a 2 3

P2 50 8 260 (no.)

S

S SR S S S

R S

R S S

RR

R S

of sporulating

PD is the result of a seedling family selectionprocess. A sample of accessions of wild andnative cultivated potatoes as candidate

Population PD

Resistant to no. of isolates

Figure 2. Mean AUDPC values of classes of VP individuals resistant to 0-3 isolates.

resistant to isolate 275 was smaller thanthat of the individuals susceptible to that iso­late (mean AUDPC=317, 63 individuals).

Table 2. Response' of 99 VP plants ta inoculation of detached leaflets with five isolates of Phytophthora infestons.

1.7 5.4 9.2 13 16.8 20.6 24.3 28.1 31.9 35.7 39.4 43.2 47 50.8 54.6 More

,-

and low temperature. A randomized 2-blockdesign was used. The experimental unit wasa milk bottle containing three stems of a POgenotype. The plants were inoculated at nightwith isolate 260 (complex virulence to S.demissum Rgenes, see Table 1), at a concen­tration of 13,000 sporangia/ml. The epidemicdeveloped after 4-7 d and visual readings ofthe percentage of diseased fol iage were takenthree times at 2-d intervals. The experimentwas repeated after 4 wk, and a two-factorANOVA (factors PO genotype and block,nested in repetition) was run on the meanpercentage of diseased foliage calculated overthe three readings. There were significantdifferences between the PO individuals, al­though no groups could be separated bymultiple comparisons of means. Based onthe conditions of the screening facility, theoverall level of disease was different for eachblock within each repetition.

Figure 3 shows the frequency distributionof diseased foliage for the PO individuals,which fits a normal distribution. The overalllevel of resistance of the PO population (27%diseased foliage) observed was higher thanthat of the resistant control, Canchan (4%).But it was much lower than that of the sus­ceptible check, Yungay (33%).

Overall, high levels of resistance that varygradually between sister individuals depictthe image of true quantitative resistance

•.11 ,1.1120

30

10

o - +-+_ .•

was, of all nine progenies, closest to the valueof the resistant standard, variety Catalina(AUOPC=98). The individuals had AUOPCvalues between 65 and 240, displaying anormal distribution. Twenty percent of theindividuals had the same resistance as thestandard, or a higher level. All individuals ofthis progeny are male- and female-fertile and65% of them produce more than 2% unre­duced pollen grains. This progeny also hassmooth round and oval-shaped tubers withshallow eyes and yellow skin. The yellow­fleshed starchy tubers have good culinaryquality. The cross of the parents was repeatedin Peru to produce the PO mapping popula­tion.

Individuals (no.)50 r~ ~~- ~- - ---

40

All individuals of population PO are male­and female-ferti Ie and flower profusely in thegreenhouse at C1P-Huancayo, Peru. Plants arevigorous, but seem to be vulnerable to infec­tion by mosaic viruses-a feature frequentlyobserved in wild and native potatoes. Intro­gression of virus resistance in subsequentcrossing generations will be necessary.

PO resistance in acontrolled-environment testPO plants and their parents were grown

in pots in the greenhouse at Lima, during the1996 winter season. Stems with completefoliage were used in a resistance trial in ascreenhouse equipped with mist irrigation toconstantly maintain high relative humidity

Diseased foliage area (%)

Figure 3. Population PD: frequency distribution of diseased foliage area (%) measured on 240 individuals andthe Pand Dparents in 2 repetitions, Lima, 1996.

136 Program 3

caused by many additive genes. Thus, the POpopulation is useful for molecular mapping ofquantitative trait loci for resistance. More re­sistance studies must be done under actualfield conditions and in different environmentsto elucidate the stability and sustainability ofthe resistance detected.

Testing for R genes in population POMost of the PO individuals developed

foliage damage of more than 15-20% afterinoculation with a virulent isolate of P.infestans (Figure 3). A small fraction of in­dividuals exhibited less than 10% damageand preponderantly necrotic lesions. There­fore,it is preferable to test this popu lationfor the segregation of putative, isolate-spe­cific resistance as well.

Two repetitions of a test for sporulation ondetached leaflets of 218 PO individuals weredone using the isolate P2 (Table 1). Of 218individuals tested, 9 did not sporulate in oneof the two repetitions, and 13 did not sporu­late at all. No necrotic lesions developed, andthe size of the lesions that did develop onthese nonsporulating leaflets was similar tothat on leaflets of other individuals on whichthe pathogen sporulated. Further tests withthis and other isolates of P. infestans on thePO individuals and on progenies from crossesof sisters and backcrosses to the 0 parent arenecessary to elucidate whether race-specificresistance is also segregating in this quantita­tively LB-resistant material.

Conclusions

Population VP expressed high levels of resis­tance in the field, with little variation amonggenotypes. Besides the population's overallfield resistance, race-specific interaction ofindividuals was detected in detached-leafletassays. These race-specific resistances had asmall favorable effect on resistance in thefield.

We will use male-sterile individuals of theVP population as females in backcrosses with

the susceptible P parent and with a dihaploidtester clone to obtain advanced backcrosspopulations for further analysis of the resis­tance and use in breeding.

Population PD had a wide range of gradu­ally different resistance levels in a repeatedcontrolled-environment, foliage resistanceassay, thus allowing the separation of most­resistant from most-susceptible individuals bystatistical means. High levels of quantitativeresistance to LB as well as good fertility andthe production of unreduced (2x) gametes,earliness, yellow tuber flesh, and other goodagronomic characteristics of the PO popula­tion make it a valuable material for breeding.Introgression of resistance to LB from thispopulation into cultivated potato appears tobe possible. To carry out this introgressionefficiently, we will need to genetically mapquantitative resistance loci as a preconditionto marker-assisted selection.

Selected Reading

Malcolmson, J.F. and W. Black. 1966. NewR-genes in Solanum demissum Lindl.and their complementary races ofPhytophthora infestans (Mont.) deBary. Euphytica 15:199-203.

Ramanna, M.S. and J.G.Th. Hermsen.1974. Unilateral "eclipse sterility" inreciprocal crosses between Solanumverrucosum Schlechtd. and diploid S.tuberosum L. Euphytica 23:417-421.

Stewart, H.E. 1990. Effect of plant age andinoculum concentration on expression ofmajor gene resistance to Phytophthorainfestans in detached potato leaflets.Mycol. Res. 94:823-826.

Trognitz, B.R., G. Chacon, H. Pinedo, andM. Eslava. 1995. Screening for R genescausing race-specific resistance to lateblight in wild potato species. Am. PotatoJ.72:662.

(IP Program Report 1995-96 137

G.A. Forbes, P.]. Oyarzun, A. Pozo, and M.E. Ordonez!

Host Specificity of late Blight Pathogenon Potato and Tomato in Ecuador

The mating type test was performed bypairing isolates with known Aland A2 geno­types on clarified rye A agar. The presence orabsence of oospores was recorded after 1Sd.Mitochondrial haplotype was determinedwith the polymerase chain reaction procedureusing primers developed and provided byG.W. Griffith, University of Bangor, Bangor,Wales, U.K.

Results

All isolates were inoculated on 11 potatodifferential plants containing 1 each of 11known R genes for resistance and 4 tomatodifferential cultivars. Detached-leaf tests ofaggressiveness were performed on 3 potatocultivars and 3 tomato cultivars using 7 iso­lates from each host. Isolate resistance wasassessed on 10% V8 agar amended with Sand 100 ppm metalaxyl.

Isolates were cultivated in still culture ofpea broth or on rye B agar for 7 d and gelswere stained for glucose-6-phosphateisomerase (GPO and peptidase (PEP). Elevenrandomly selected isolates from tomato wereanalyzed for restriction fragment length poly­morphism (RFLP) fingerprints using the mod­erately repetitive probe RGS7 developed inthe laboratory of W.E. Fry at Cornell Univer­sity.

Genetic description of P. infestansAll isolates from potato had the allozyme

genotype of 96/1 00 for Gpi and 100/100 forPep (Table 1), and the mitochondrial DNAhaplotype of IIA. This multilocus genotype isidentical to that found for the lineage EC-l,which was described as the dominant lineageon potato in Ecuador. Thirty genotypes werefingerprinted with probe RGS7. Of these, 28

Materials and Methods

This study was begun to elucidate two as­pects of P. infestans host specificity: whetherpotatoes and tomatoes are attacked by thesame population of P. infestans in Ecuador,and what role specific virulence plays in de­termining host specificity.

In Ecuador, potato and tomato are cultivatedyear-round. Late blight caused byPhytophthora infestans occurs in potato andtomato at any stage of plant growth after emer­gence, because of the continuous presenceof inoculum. Potato and tomato are not gen­erally grown in the same area, but produc­tion zones for the two crops can be within afew ki lometers of each other or even contigu­ous. Occasionally, we have seen potato andtomato grown on the same farm, and on rareoccasions in the same field. Host specificityhas important implications for managementofthe disease, especially in areas where bothcrops are grown in the same vicinity. Farm­ers need to know whether their crops arethreatened by nearby alternative hosts that arebadly infected. Researchers and extensionistsworking on potato and tomato must coordi­nate efforts if the pathogen is equally aggres­sive to both hosts.

Several markers were used to characterizeboth potato and tomato populations.

A total of 120 isolates, 60 from potato and60 from tomato, were collected from centraland northern Ecuador, between November1994 and January 1996. Approximately equalnumbers were taken from the two zones.

1 CIP, Quito, Ecuador.

138 Progrom 3

Table 1. Genotype characterization of populations of Phytophthora infestans on potato and tomato in Ecuador.

US-l?

EC-I?EC-1EC-1 d

Lineage

US-1

US·1

RFLP fingerprint'

1010l0QOQ10011 01010101010Q1001101010101010110011010Not tested

Not tested

111110100Q00111111010010011 010Nflttested

No relation between tomato and potatoavirulence genes in P. infestans could be de­duced from our results. Isolates that wereavirulent on all potato differentials were viru­lent on all tomato differentials (Table 2).Therefore, all avirulence genes for tomatoexpressed in this study appear to be indepen­dent of all known potato avirulence genes.

(IP Program Report 1995-96 139

Pathogenic aggressivenessResu Its are presented as the average over

all cu Itivars for each host and all isolates fromeach origin (tomato or potato). There was avery clear and statistically significant(P<O.OOOl) interaction between origin of iso-

Some isolates from potato did not infectany of the four tomato differentials. Simi larly,some isolates from tomato did not infect anypotato differentials, including those free ofknown R genes.

tials we used. Pieralbo, reportedly a major­gene-free isoline of the Ph2 differentialPieraline, should have behaved similarly toFMX-93, also putatively free of major genes.However, these two tomato cultivars inter­acted differentially with some isolates, thusindicating the interaction of a hitherto un­known major gene (Table 2).

92/10092/10092/10092/100

100/100100/100100/100

100/100

Gpi D

86/10086/10086/10086/10096/10096/10096/100

96/10028

Number

c. Underlined bands indicate polymorphism within lineages.

d. Indicates published RFlP and isozyme genotype, which define tnatlineoge.

Tomato

Tomato

Tomato

Tomflto

Host

All isolates from tomato, except for one,had the allozyme genotype of 86/100 for Cpiand 92/1 00 for Pep (Table 1), which is defini­tive for the globally distributed lineage US-l.Eight of 10 isolates fingerprinted had the US­1 genotype. Two were similar, but lackedband 9, and one isolate lacked both band 9and 7. All tomato isolates but one were 18mitochondrial haplotypes, and all were Almating type.

Two race-specific genes in tomato werereported previously, but our data indicate thatthere is at least one more in the four differen-

Specific virulenceThe specific viru lence patterns of potato

and tomato populations of P. infestans differedgreatly. Isolates were generally highly viru­lent on their own host differentials, but noton the alternative host differentials (Table 2).In several cases, isolates from one host didnot infect any of the other host differentials,even those free of known major genes for re­sistance.

had the fingerprint of EC-l and the fingerprintsof the other 2 were similar to EC-l, but lackedband 10. All potato isolates were IIA mito­chondrial haplotypes and A1 mating type.

Table 2. Specific virulence patterns of P. infestans isolates coming from potato or tomato and inoculated on major-gene differential plants of both hosts.-l:>.o~

.g1j~

Iso[otes collected from potato

Potato differentials' Tomato differentiolsb Pothotype frequency Potato differentials'

Isolates collected from tomato

Tomato differentiolsb

0,1,3,4,7,8,10,11

0,1,3,4,7,8,10,110,1,3,4,7,8,10,110,1,3,4,7,10,11

0,1,2,3,4,6,7,10,110,1,2,3,4,6,7,8,10,110,1,3,4,7,8,110,1,3,4,7,8,110,1,3,4,7,8,11

0,1,3,4,7,110,1,3,4,7,10,110,1,3,4,7,8,10,11

0,1,3,4,6,7,10,110,1,2,3,4,6,7,10,110,1,2,3,4,6,7,8,10,110,1,2,3,4,6,7,8,9,10,11

0,1,2,3,4,6,7,8,9,10,11

0,10,1,3

°0,3

0,1

0,3No infectionC

°0,30,1

°No infection!

0,1

0,1,3

°0,30,1,3

2311

2

0,3,7

0,3

°0,2,3No infectionC

3

0,2,3,7

No infectionC

No infection'0,4

0,110,3,70,lO,11

0,1,3,70,1,3,70,1,3,4,7,8,10,11 d

0,1,2,30,1,2,30,1,2,30,1,2,30,1,2,3

0,1,2,30,1,2,3

20,1,2

0,1,2,30,1,2,3

0,1,30,1,30,1,3

0,1,2,30,3

15

128

65321

11

111

1

1

1

a. Numbers represent major genes overcome by that pothotype.

b. Numbers represent fOUl tomato differentials:0 = fMX-93, 1 == Pierolbo, 2 = New Yorker, and3 = Piemline.c. These individuals did not infect any ohhe differentials, includingfhose considered free of major genes (0).d. This tomato isolate that was highly virulent on potato belongs to the EC-l lineage.

(IP Progrom Report 1995-96 141

Figure 1. Pathogenic aggressiveness of Phytophthora infestans isolates from potato and tomato, inoculated onboth hosts.

We do not know whether the one EC-l iso­late found on tomato indicates the initiationof evolution toward aggressiveness on to­mato, or simply represents a weakly patho-

tomato

Isolates from

Our data amply address the first objective ofthe study, that is, to determine whether popu­lations of P. infestans attacking potato andtomato differ in Ecuador. All our data indi­cate that the two popu lations are distinct. Allisolates collected from potato for this studybelong to the EC-l lineage. All but one of 60isolates from tomato belonged to the globallydistributed lineage U5-1. That single varianthas the same dilocus allozyme genotype asEC-l and probably belongs to that lineage.

Discussion

Potato 0

Tomato ~ ..

~.

2

3

potato

Isolates from

4

Lesion diam (em)

o

MetalaxylThere was a marked and statistically signifi­

cant difference in three levels of sensitivity tometalaxyl between tomato and potato isolates(Table 3). More than half the isolates tested frompotato (30 of 59) were resistant to metalaxyl,but only 3 of 43 isolates from tomato were re­sistant. In contrast, only 5 of 59 isolates frompotato were intermediately resistant; 17 of 43from tomato were intermediate.

late (tomato or potato) and lesion diametercaused on either host (Figure 1). On the aver­age, isolates from tomato caused lesionsabout 2 cm greater in diameter on tomato thanon potato. Isolates from potato caused lesionsabout 1 cm greater in diameter on potato thanon tomato.

Table 3. level of sensitivity to metalaxyl of isolates of P. infesfans from potato and tomato in Ecuador.

Chi-square value for independence = 28.81, P= 0.001,2 degrees of freedom.

523

Intermediate

2417

Susceptible

Sensitivity level

Pathogenic aggressiveness appears to bea more important factor than specific viru­lence in determining host specificity. Therewas a clear interaction between origin of iso­lates and their ability to infect tomato andpotato (Figure 1). The isolates from potatoinfect potato more aggressively than tomato,whereas the opposite is true for isolates fromtomato. That finding supports other studiesthat showed that host specificity was deter­mined by quantitative rather than qualitativefactors.

We sampled extensively in the central andnorthern parts of the country and it is highlyunlikely that all these fields had cultivars withPhl. Separate populations of P. infestans arefound on potato and tomato in Brazil, thePhilippines, and parts of the Netherlands. Ph 1is also unlikely to be responsible for hostspecificity in those countries.

Our study also leads to other interestingobservations regarding specific virulence.

Apparently, P. infestans has differentaviru lence genes for potato and tomato, atleast among those that can be identified withexisting differential cultivars of both hosts. Wefound that several isolates, which possess allknown avirulence genes for potato, infect allfour tomato differentials (Table 2). Therefore,avirulence genes for potato must not elicit ahypersensitive response in potato. Similarly,several isolates, which did not infect any to­mato differentials, were highly virulent onpotato (Table 2).

One aspect of host special ization that re­mains unclear is whether P. infestans can

303

Resistant

Potato

Tomato

Origin of

isolates

The second objective of the study, to elu­cidate the role of virulence in host specific­ity, was less well addressed by our results,but we believe that a working hypothesis canbe developed. Our best interpretation is thathost specificity is not determined by viru­lence, but rather by pathogenic aggressive­ness.

genic isolate found by chance. Nor do weknow whether the lesion was large or sporu­lating when taken from the field. Furthermonitoring is required to determine the sig­nificance of this finding.

In general, however, management of lateblight is simplified in Ecuador. For allpractical purposes, and until populations ofP. infestans change, farmers do not need toworry about cross infection from nearbyalternative hosts, at least until EC-l is shownto be an aggressive pathogen of tomato.Th is management recommendation issupported by field observations we madewhere epidemics occurred in one of thehosts wh i Ie nearby fields of the alternativehost remained clean.

None of the EC-l potato isolates infectedNew Yorker, the tomato cultivar containingthe Phl gene (Table 2). The existence of anavirulence gene for Phl, which is costly forthe pathogen to lose, would be an attractivemodel to explain host specificity. Unfortu­nately, we were not able to survey cultivarsbeing used in Ecuador and we do not knowwhether Phl is common. We do not believe,however, that it occurs at a rate that wouldexplain host specificity as seen in Ecuadorand elsewhere.

142 Program 3

evolve into an aggressive tomato pathogenwith no loss of aggressiveness on potato.There seems to be evidence for both sides ofthe argument. One study done recently inNorth America demonstrated that certaingenotypes of P. infestans can infect both hostswith a high level of aggressiveness. It is notevident, however, that this phenomenon isuniversal. If dual aggressiveness were an in­herent capabi Iity of P. infestans, and if adap­tation to tomato aggressiveness occurred rela­tively quickly (> 10 vegetative cycles), then itseems logical that the dually aggressive geno­types would quickly dominate both hosts.

That is not the case in Ecuador and otherparts of the world, where distinct genotypesare found in close association with each host.

Our data do not conclusively demonstratethat aggressiveness to tomato results in a lossof aggressiveness on potato, because the twopopu lations represent different lineages of thefungus. We could have addressed this pointmore clearly if we had studied tomato andpotato populations with one lineage. In 5years of sampling from potato in Ecuador,however, we have found only one isolate

belonging to US-1, and it was isolated fromthe diploid potato species Solanum phureja.

One plausible explanation for the incon­sistency between observations in NorthAmerica and in other parts of the world isthat genotypes outside North America do nothave the genetic potential for developing highlevels of aggressiveness on both hosts. Thegenotypes that do attack both hosts equallyin North America were recently introducedfrom Mexico, the center of origin of the patho­gen. If that is the case, the introduction of theNorth American genotypes to other parts ofthe world will have major implications formanagement, especially in areas where thetwo crops are grown in close association.

Selected Reading

Legard, D.E., T.Y. Lee, and W.E. Fry. 1995.Pathogenic specialization inPhytophthora infestans: Aggressivenesson tomato. Phytopathology 85:1356-1361.

Turkensteen, L.). 1973. Partial resistance oftomatoes against Phytophthorainfestans, the late bl ight fungus. Thesis.University of Wageningen, Netherlands.

(IP Progrom Report 1995-96 143

M. QuercP, G. Brigneti2, J. Garcia-Mas2, and D.C. Baulcombe2

Use of Natural Resistance Genes forTransgenic Resistance to Potato Viruses

There are, however, concerns about thebiosafety of this approach to virus resistance.In addition, pathogen-derived resistance maybreak down under high inoculum pressureor could promote evolution of resistance­breaking viral isolates. Therefore, we are at­tempting to develop a molecular breedingapproach to virus resistance in potato thatdoes not provoke these concerns and thatdoes not have the limitations of conventionalplant breeding. "Molecular breeding" is thetransfer of individual genes between plantsusing transformation rather than intercross­ing. It has been demonstrated recently thatmolecular breeding could be applied to vi­rus resistance. The N gene and its phenotypeof resistance against tobacco mosaic viruswas successfully transferred by transforma­tion from tobacco to tomato.

approach to genetically engineering virus re­sistance is pathogen-derived resistance in­volving expression of transgenes that containvirus-derived sequences. This has proven ef­fective against many different types of plantviruses. The protection is expressed as pre­vention of infection, a delay in the onset ofvirus accumulation, or symptom developmentin systemically infected leaves.

Although the technology to isolate diseaseresistance genes was developed only recently,it has now been refined to the level that itcan be applied even in crop plants such aspotato. The most important components ofthis technology (Figure 1) include the devel­opment of genetic maps in which there is ahigh density of molecular markers. Using themarkers that are closely linked to and flankthe resistance gene of interest, it is possibleto identify deoxyribonucleic acid (DNA)clones that span the interval between the

Breeding for virus resistance, a major com­ponent of most breeding programs, is gener­ally regarded as being the best strategy forlong-term virus control. This approach is ham­pered, however, by the limitation of suitablesources of resistance. In the past, the intro­gression of genetic sources for plant resistancehas been successfully applied to develop alimited number of virus-resistant cultivars.Although plant breeding for virus resistancestill has great potential, there are limitationsto this conventional approach. An appropri­ate source of resistance may not be avai lable,the resistance may be tightly linked to unde­sirable traits, or it may be multigenic and assuch difficult to use in breeding programs.

One of the principal threats to potato(Solanum spp.) cu Itivation is the susceptibi 1­ity of potato to pests and diseases. Viral dis­eases in particular cause significant qualita­tive and quantitative crop losses. The mostwidely used strategies for control of virus dis­eases focus on methods to prevent infectionor on genetic resistance. Resistance describesthe general response of the plant in whichthe effect of virus infection is reduced or elimi­nated. This ranges from tolerance of or hy­persensitivity to the most durable extremeresistance or immunity. Few sources of ex­treme resistance provided by dominant genesexist for some potato viruses. Examples ofdurable resistance genes so far include Rx andRy genes conferring extreme resistance topotato virus X (PYX) and potato virus Y (PYY),respectively.

Plant genetic engineering is an alternativeto conventional breeding for resistance. One

1 ClP, Lima, Peru.2 Sainsbury Laboratory, Norwich, U.K.

144 Program 3

M39, M33

Ry

M41, M53

M43GP259

- ---- ---GP163

R S 104 301 54 143 344 249

genes have been found so far. The establish­ment of stable virus resistance is of high pri­ority, and the development of cultivars resis­tant to the three viruses has always been agreat challenge for breeders. Molecularbreeding of resistance to PVX and PVY wouldbe an important and significant step in thatdirection.

Figure 2. Detail of an AFLP-gel autoradiographshowing resistant (R) and susceptible (S)bulk DNA samples (each consisting of DNAfrom 10 individuals) and six individualsfrom the F] population (top), andschematic representations of thecorresponding chromosomes (bottom).The segregation of marker M39 isindicated on the autoradiograph. Thelocation af additional markers andrecombination events in the F] lines isindicated in the battam panel.

First, resistant plants challenged with ei­ther virus do not develop visible symptoms,and virus accumulation cannot be detectedby either enzyme-linked immunosorbent as­say (ELISA) or ribonucleic acid (RNA) hybrid­ization. There is no evidence that these resis­tance traits can be overcome by high inocu­lum pressure.

The potato has a good regeneration andtransformation ability and, in general, pro­vides a good background for the applicationof recent developments in molecular biology.To exploit this potential, the molecu lar vi rol­ogy unit of C1P is collaborating with theSainsbury Laboratory, U.K., on the charac­terization, isolation, introduction, and expres­sion of plant-derived resistance genes intransgenic potato plants. The immediate tar­gets of this program are the Rx and Ry genesof potato, for the reasons described below.

A second consideration was the durabilityof the resistance conferred by Rx and Ry. Inthe case of Ry, the resistance is effectiveagainst all known isolates of PVY, whereasRx is overcome by a resistance-breaking iso­late (HB), although it has not become a prob­lem in most potato-growing areas.

classified into four groups on the basis of theirinteractions with the dominant resistancegenes Nx and Nb, which control a hypersen­sitive response, and the extreme resistancegene Rx. The Rx resistance is effective againstall known isolates of PVX, with the excep­tion of PVXHB, which can overcome all knownresistance genes. PVXHB is found in Boliviaand a limited number of sites in the Andeanregion. Several Solanum spp. carry Rx genesfor extreme resistance. Those from S.tuberosum subsp. andigena and S. acaule arethe most commonly used in breeding pro­grams.

The potential to carry out molecular breed­ing with both genes simultaneously wouldhave agronomic benefits, because these vi­ruses interact to produce severe crop losses.In addition, studies have shown that PVX orPVY reduce the durability and the degree ofresistance to PLRV, for which no immunity

146 Progrom 3

Mapping RyA chromosomal assignment of RY,ro was the

first step toward the molecular cloning of RY,rofrom potato by a map-based approach. Mo­lecular linkage maps of potato and tomatogenomes were readily available, so we usedamplified fragment length polymorphism(AFLP) technology as a source of molecularmarkers linked to Rysro (Figure 2). Ry from S.stoloniferum has been mapped at theSainsbury Laboratory on the top arm of thepotato chromosome XI.

A second step involved constructing ahigh-resolution genetic map around the Rylocus. That was obtained using an F, segre­gating population of 360 plants. Several AFLPprimer combinations were tried on DNApools of resistant and susceptible plants. TwoAFLP markers (M17 and M6) at either side ofthe gene (separated by a single recombina­tion event) and two more markers (M45 andM5) cosegregating with Rywere found. DNAmarkers linked to the resistance gene havebeen used to screen 22 CIP crosses that carryRYsro and segregate for the resistance.

To increase the map resolution of the mark­ers relative to the resistance gene, an addi­tional 3,079 F, segregating progeny (1,779progeny from the 1st year and 1,300 from the2nd year) have been screened. The resistantparent (I-1 039) of this new cross was the sameas the one originally used at the SainsburyLaboratory for chromosomal assignment ofRysro and construction of the first genetic map.

Results

The screening has been carried out in sev­eral stages. First, polymerase chain reaction(PCR) markers were used so that plants withrecombination events close to the resistancegene could be identified (i.e., plants with re­combination between the markers). The flank­ing PCR markers used in the screening of thenew cross were M39b and GP163. A fewhundred recombinants were found in this in­terval. Using the GP259 PCR marker, thenumber of recombinants was reduced. Fromthese data it was also possible to confirm theorder of the PCR markers in the genome rela-

tive to each other and, following resistancetesting of the recombinant plants, relative to RY,ro'

The recombinants identified were ana­lyzed by AFLP using the primer combinationsfor the closest markers: M17, M5, M45, andM6. The new map obtained with this secondmapping population was compared with theprevious map. The order of the markers isconserved although the genetic distanceshave increased slightly. We have been ableto separate M39b from M33, but M17 is nowcosegregating with M5 and M45 (Figure 3).

To obtain an estimate of the physical dis­tances around the Ry locus, we began screen­ing bacterial artificial chromosome (BAC) andcosmid libraries. We identified a single BACclone (cBAC-15) of 110 kb containing threeof our markers (M17, M5, and M45) althoughit is from a chromosome that carries the ry(rather than the Ry) allele. We are now at­tempting to map the ends of cBAC-15 to ob­tain new markers in the vicinity of Ry.

If the currently available libraries do notyield Ry, we will prepare new libraries fromdihaploid plants that have been generatedfrom the tetraploid parent 1-1 039 (which car­ries Ry in the simplex condition). Whenclones that span the Ry locus have been pro­duced, we will identify the precise locationof the gene by complementation. Differentfragments of DNA from the Ry interval willbe transformed into susceptible plants and thetransgenic lines will be tested for resistance to PVY.

Discussion

For several years CIP has invested a great dealof effort in searching for sources of resistanceto several viruses in the wide range of potatogenotypes in the germplasm collection heldat ClP. Breeding for virus resistance was fo­cused on the three major viruses, PYX, PVY,and PLRV. The main goal was the develop­ment of advanced materials with combinedresistance to PYX, PVY, and PLRV to allowfarmers to keep their own seeds season afterseason, in this way reducing their cost of po­tato production.

CIP Program Report 1995-96 147

GP163

(not a large piece of the whole genome) sothat the recipient genotype remains largelyintact. Transformation with natural resistancegenes is potentially the shortest and most pre­cise procedure for introgressing resistancegenes into a crop species.

The ultimate aim of this work is to supportincreased potato production in developingcountries. But we also expect the project togenerate knowledge of the mechanisms in­volved in virus resistance as well. We per­ceive a practical application of this new ap-

M33 M39bM39b

0.56 0.34 M33 I 6/1779

M45. M5 0.28M17 M45 M5 1 5/1779

0.78 Ry".? j 14/17790.56

M53 M41 M6

1.11

M430.27

3.93 77/1779GP259

1.39

GP163GP259

2.2540/1779

Figure 3. High-resolution map of the Ry,!, region on the top arm of potato chromosome XI. The genetic distancesbetween markers were inferred from an F] population of 360 plants (chromosome on left) and for apopulation of 1,779 plants (chromosome on right). The number of recombinant progeny obtained fordifferent intervals is indicated on the right. In the larger population, markers M39b and M33 wereseparated. An additional 1,300 plants are being analyzed to refine the relative positions of markersM17, M45, and M5.

The strategy followed was to first introducePYX and PVY extreme resistance genes fromSolanum tuberosum subsp. andigena intoadvanced breeding populations, then to com­bine PYX and PVY extreme resistance withresistance to PLRV and possibly other patho­gens. Genes controlling resistance often origi­nate from wild species; undesirable traits maybe closely linked to the resistance gene andmay be difficult to eliminate.

In our transformation approach, we willtransfer only isolated and characterized genes

148 Program 3

proach over the medium term and long term.In the medium term, practical applicationswill be achieved through the identificationand isolation of natural genes that confer ex­treme resistance to PYX, PVY, and PLRV, andtheir insertion into available susceptible butagronomically important potato cultivars.

Over the long term, we plan to integratethis nonconventional approach to optimizeadvances on resistance to other pests andpathogens already achieved through conven­tional breeding. Of particular interest will bethe combination of conventional andnonconventional breeding methods to in­crease levels of PLRV resistance. In addition,molecular breeding methods can be used toadd resistance to viruses (Rx and Ry genes) toadvanced materials with resistance to otherpathogens.

The concept of plant-derived transgen icresistance provides an attractive strategy to

produce a novel but genetic form of viruscontrol by transforming crop plants withnucleotide sequences derived from the plantgenome itself. Natural resistance genes forplant protection would eliminate most of thebiosafety concerns associated with the use ofvirus-derived sequences in transgenic plants.

Selected Reading

Bendahmane, A., K. Kanyuka, and D.C.Baulcombe. n.d. High resolution geneti­cal and physical mapping of the Rxgene for extreme resistance to potatovirus X in tetraploid potato. Theor. App!.Genet. (I n press.)

Brigneti, G., J. Garcia-Mas, and D.C.Baulcombe. 1997. Molecular mappingof the potato virus Y resistance. Theor.App!. Genet. 94: 198-203.

(IP Program Report 1995-96 149

Encapsidation of PSTVd in PLRV Particlesand Its Transmission by Aphids

M. QuerciJ, R.A. Owens2, and L.P. Salazar!

Like all known viroids, potato spindle tuberviroid (PSTVd) is an independently replicat­ing agent, which completes its infection cyclewithout generating either a capsid or otherviroid-specific proteins. Its genome is a small(359 nt), single-stranded, covalently closedcircular ribonucleic acid (RNA) moleculewhose extensive regions of intramolecularcomplementarity are responsible for its un­usual stability in vivo.

The natural spread of PSTVd in potato wasknown to occur only by foliar contact or bo­tanical seed.

In contrast to PSTVd, potato leafroll virus(PLRV), a member of the genus Luteovirus, isreadily transmitted by aphids, with Myzuspersicae being the most efficient natural vec­tor. Like ailiuteoviruses, PLRV is restricted tothe phloem tissue of infected plants, andaphid transmission is both persistent andnon propagative. PLRV has a narrow hostrange, and the virus is commonly found wher­ever potatoes are grown.

Earlier we confirmed that M. persicaecould transmit PSTVd to potato and other testplants only when the source plant was dou­bly infected with PLRV and PSTVd. In someexperiments, PSTVd transmission reached100%; but no transmission was observed fromsource plants infected with the viroid alone.

Transmission by Aphids

Occasional PSTVd contamination of PLRVisolates maintained at CIP provided the firstindication that PLRV might facilitate aphid

1 CIP, Lima, Peru.2 Beltsville Agricultural Research Center, Beltsville,

Maryland, USA.

150 Progrom 3

transmission of PSTVd. Additional epidemio­logical evidence for an association betweenPSTVd and PLRV in field-grown potatoes wassubsequently obtained by testing plants grow­ing at several sites in China for the presenceof PSTVd and PLRY. A total of 880 plants fromthree sites were tested by nucleic acid spothybridization (NASH) in 1994, and Table 1summarizes the results from these analyses.

Rates of infection for both PLRV and PSTVdvaried considerably, ranging from 3.6% to86% and 0.9% to 27.2%, respectively. Vec­tor pressure was highest at the Bashang Insti­tute (Hebei Province).

As expected, the incidence of PLRV at thatsite appeared to be somewhat greater than atthe others. Most (but not all) PSTVd-infectedplants at all three sites were also infected withPLRV. No effect on either host genotype orsite was identified for aphid transmission ofeither PLRV or PSTVd, and the pooled datawere analyzed to test the independence ofPSTVd and PLRV distribution. The x2 value(29.68) was high ly sign ificant, strongly sug­gesting that PLRV facilitates the spread ofPSTVd under field conditions.

Additional aphid transmission experimentswere carried out to more precisely charac­terize the mode of PSTVd transmission by M.persicae.

Materials and Methods

Potato clone OTO-33 (CIP No. 800174), aSolanum tuberosum x S. andigena hybrid sus­ceptible to PLRV and PSTVd, was used as bothinoculum source and test plant. Plants dou­bly infected with PLRV and PSTVd were ob­tained by initially inoculating them with PLRV

rate ('Yo)

(lP Progrom Report 1995-96 151

Feeding on healthy cabbage before trans­fer to the test plants reduced, but did not elimi­nate, the ability of aphids to transmit PSTVdfrom doubly infected source plants. Thus,PLRV-mediated transmission of PSTVd by M.persicae appears to be of the persistent type.

To further characterize the nature of theassociation between PSTVd and PLRV, a se-

Fifteen and 45 days after the TAP, inoculatedplants were tested for the presence of PSTVdand PLRV using a combination of the NASHtest and enzyme-linked immunosorbent as­say (ELISA). M. persicae was able to transmitPLRV under all conditions tested (Table 2).PSTVd transmission, in contrast, was ob­served only when the aphids were allowedto acquire the viroid from doubly infectedsource plants. Comparison of data presentedin rows 3 and 4 shows that aphids allowed tofeed sequentially on plants singly infectedwith PLRV or PSTVd were unable to transmitPSTVd.

Nature of PSTVd and PLRV Association

SamplesSite

A final 2-day passage on healthy Chinesecabbage was included in one experiment.After a 3-day transmission access period(TAP), aphids were killed by spraying plantswith a contact insecticide.

Apterous aphids from a nonviruliferouscolony of M. persicae were raised on Chi­nese cabbage (Brassica pekinensis (Lour.)Rupr.). One month after PLRV or PSTVd in­oculation, apterous aphids were allowed a3-day acquisition access period on either sin­gly or doubly infected source plants. Aphids(5 aphids/plant) were then transferred toyoung uninfected potato plants by placing theinsects on filter paper squares using a sterilebrush and then allowing them to walk onto aplant leaf.

by means of its vector, M. persicae, and thenmanually inoculating them with sap fromPSTVd-infected tomato (Lycopersiconesculentum cv. Rutgers). After inoculation,plants were maintained in a growth chamberand periodically tested for PSTVd and PLRVinfection.

Table 1. Incidence of PlRV and PSTVd at three potato-growing sites in China, 1994.'

a. Datopresentedas no. of infected planlsino; of inoculated plants.

b. Aphids were allowed two acquisitioli feadings, on PLRV-infected plants followed by the second on

PSTVd-infected source plants.

Table 2. Aphid transmission of PlRV and PSTVd to potato variety DTO-33.

PSTVd

No (015)

No (015)No (0/3)

No (0/5)Yes (3/5)

Yes (1/5)

Successful transmission a

PlRV

Yes (4/5)

Ves (2/5)Yes (2/3)

Yes (1/5)

Yes (4/5)

Yes (1/5)

To determine whether transencapsidationof PSTVd by PLRV was responsible for itsobserved aphid transmissibility, two types ofsamples were treated with micrococcal nu­clease: PLRV virions isolated from doubly in­fected leaf tissue, and mixtures of vi rions iso­lated from singly infected plants plus suffi­cient PSTVd RNA to produce a comparableratio of PSTVd/PlRV

were present in PCR reactions containingRNA derived from either singly (lane 3) ordoubly infected (lane 2) plants. The corre­

sponding PSTVd-specific product was presentonly in reactions containing RNA derivedfrom doubly infected tissue (lane 5). Whenvirions were isolated from a mixture of leavescollected from singly infected plants, noPSTVd-specific PCR product was produced(compare lanes 5 and 6).

Parallel incubations were carried out, eachcontaining the same amount of virus but only

Trial experiments showed that 15-min in­cubation at 30°C with 1 xl 0.3 units/fll micro­coccal nuclease completely destroyed con­centrations of PSTVd similar to those foundin PLRV virions isolated from doubly infectedtissue (results not shown).

Passage

None

CllinesecobbageNone

Chinese cabbage

None

Chinese cabbage

Inoculum source(s)

PLRV

PLRV

PlRV ~ PSTVd b

PLRV ~ PSTVd b

PLRV + PSTVd

PLRV + PSTVd

ries of virus purifications were carried outusing leaf tissue collected from singly anddoubly infected potato plants. The first ex­periment compared the amounts of PSTVdRNA associated with virions purified fromdoubly infected plants with those associatedwith particles isolated from a pooled sampleof leaves collected from singly infected plants.PLRV was purified, and encapsidated RNAswere recovered by phenol/chloroform extrac­tion and ethanol precipitation. RNA pelletswere resuspended in sterile nuclease-freewater and reverse-transcribed using a randomhexanucleotides mixture (pdN6).

PSTVd- and PLRV-specific cDNAs were

then amplified separately by polymerasechain reaction (PCR) using the appropriatepairs of oligonucleotide primers.

As shown in Figure 1A, large amounts of aPLRV-specific product of the appropriate size

Amplifications (40 cycles) were carried outusing a 94°C (1 min), 55°C (2 min), 72°C (1 min)profile followed by a 5-min final extension at72°C; PCR products were visualized by elec­trophoresis on 5% acrylamide gels. Predictedsizes for the PSTVd- and PLRV-specific PCRproducts were 226 and 534 bp, respectively.

152 Program 3

..... 587 bp

..... 359 bp

..... 267 bp

..... 184 bp

..... 587 bp

..... 359 bp

..... 267 bp

..... 184 bp

PLRV PSTVd

M 123456

PSTVd1 2 3 4 5 6 7 8 9 10 M

L - nuclease --l L + nnclease --l

L ~ nuclease .-J L + nuclease ..J

359 bp~

267 bp~

184 bP~

587 bp~

(C)

(8) PLRV1 2 3 4 5 6 7 8 9 10 M

CIP Progrom Report 1995-96 153

(A)

Figure 1. PAGE (polyacrylamide gel electrophoresis) analysis of RT-PCR products. (A) Association of PSTVd withPLRV virions purified from different sample types: PSTVd RNA plus PLRV virions purified from singlyinfected plants (lanes 1 and 4); PLRV virions purified from doubly infected plants (lanes 2 and 5);PLRV virions purified from leaves from singly infected plants combined before PLRV purification (lanes3 and 6). (B-C) Relative sensitivity of PLRV and PSTVd RNAs to digestion by micrococcal nuclease. RT­PCR analyses were carried out using pairs of (B) PLRV- or (C) PSTVd-specific primers. Virions purifiedfrom doubly infected potato plants were incubated for 15 min at30'C in either the absence (- nuclease)or presence (+ nuclease) of micrococcal nuclease before extraction of RNA. Lanes 1-5 and 6-10 containserial threefold dilutions of the mixture of randomly primed PLRV and PSTVd cDNAs. M=DNA sizemarkers.

one containing micrococcal nuclease. Afterincubation, the undigested RNAs were iso­lated by phenol-ch loroform extraction, re­verse transcribed, and analyzed by reversetranscription polymerase chain reaction (RT­PCR). Results from these analyses are pre­sented in Figures 1Band 1C.

Each set of five amplifications (lanes 1-5and 6-10) contained a series of threefold di­lutions of the initial preparation of randomlyprimed PLRV and PSTVd cDNAs.

Samples in lanes 1-5 were derived fromuntreated virions, whereas those in lanes 6­10 were treated with micrococcal nucleasebefore RNA extraction. In Figure 1B, compari­son of lanes 1-5 with 6-10 shows that, as ex­pected, the viral genomic RNA was resistantto micrococcal nuclease digestion. The cor­responding PSTVd-specific analyses areshown in Figure 1C. Because the virions con­tain relatively low levels of viroid RNA, theamount of PSTVd-specific PCR product de­creased as the amount of randomly primedcDNA template was reduced. Micrococcalnuclease digestion, however, had no effecton the amount of PSTVd-specific PCR prod­uct synthesized.

This experiment was repeated severaltimes with different virus preparations, andthough the relative amount of PSTVd in thedifferent PLRV preparations varied, the resultsobtained were consistent and comparable.The explanation for our results is that thePSTVd associated with virions isolated fromdoubly infected plants is, like the PLRV ge­nomic RNA, located within the virus particle.Unencapsidated PSTVd RNA would havebeen degraded by the micrococcal nucleasedigestion. Expressed on a molar basis, theamount of PSTVd from doubly infected plantsis approximately one molecule of PSTVd forevery 3,000-5,000 molecules of PLRV RNA.

Discussion

In nature, plant viruses and other subviralpathogens (satellite/defective interfering RNAsor viroids) have many opportunities for inter­action. Multiple virus infections commonly

154 Program 3

occur in crop and weed hosts. That may re­sult in virus particles in which (1) individualparticles contain structural proteins derivedfrom more than one virus or (2) the genomeof one virus is encapsidated in the structuralproteins of another. This phenomenon, vari­ously known as transencapsidation, genomicmasking, or phenotypic mixing, has beenobserved many times for members of theluteovirus and potyvirus groups. Severalsobemoviruses are known to support the rep­lication of small viroid-like satellite RNAs, asin the case of velvet tobacco mottle virus(VTMoV), which has been shown toencapsidate PSTVd. Even more recently, asmall, ribozyme-containing satellite RNA hasbeen reported in association with certain iso­lates of barley yellow dwarf virus-RPV sero­type. The size of PSTVd is similar to that ofbarley yellow dwarf virus satellite RNA (i.e.,359 vs. 322 nt). Our data show that it toocan be encapsidated by a luteovirus, PLRV.

Transencapsidation of PSTVd by an assistorvirus and the resulting acquisition of aphidtransmissibility have important epidemiologi­cal implications. Although viroids are gener­ally thought to be mechanically transmitted,some workers see a different possibility. Inthat view, a viroid originating in a plant spe­cies in which it is symptomless could beencapsidated by a virus and vectored to an­other plant species. Even though that plantmight not be a host for the virus itself, it cou Idbe one in which the viroid becomes patho­genic. Our survey data from China indicatethat, even where the overall level of PLRVinfection was relatively moderate, all or al­most all plants found infected with PSTVdwere also infected with PLRV. VTMoV greatlysuppresses PSTVd replication in Nicotianaclevelandi. Nevertheless, tomato plants,which are immune to VTMoV, became in­fected with PSTVd when inoculated with vi­roid-containing VTMoV preparations. Addi­tional data will be required to determinewhether PLRV has a similar effect on PSTVdreplication in potato, but transmission byaphids or other insect vectors provides a plau­sible explanation for the presence of PSTVdin such atypical hosts as avocado, a phenom­enon occurring in Peruvian avocados.

Aphid transmission of PSTVd may be mostimportant in long-distance dissemination ofthe vi roid, thus faci Iitati ng its spread andgreatly reducing the possibility of its control.

Conclusions

An important step in breeding for virus resis­tance is the identification of specific factorsthat tend to break down or overcome that re­sistance. In the case of PLRV, no genes con­ferring immunity have been described, andthe various resistance genes known appearto act by different mechanisms. Compared tothe levels of genetic resistance to potato vi­rus X (PVX) or potato virus Y (PVY), the levelof PLRV resistance conferred by individualgenes is rather low.

In previous studies we found that the pres­ence of PSTVd can lead to a decrease in thelevel of resistance to PLRV. Infection rates of100% were observed for s. acaule accessionsOCH 13823 and OCH 13824, followingaphid-mediated transmission of virus fromdoubly infected source plants. In the absenceof PSTVd, infection rates were fourfold or five­fold lower. These two genotypes had been

shown to be resistant to both PLRV infectionand multiplication.

A similar decrease in PLRV resistance isobserved when resistant genotypes such ascv. Mariva are infected by either PYX or PVY.Knowledge of how other pathogens such asPSTVd might interfere with the expression ofgenes conferring PLRV resistance would helpin selecting the type of resistance to be incor­porated and predicting its expected durabil­ity. We are working to identify the differentcomponents of resistance to PLRV as well asto elucidate the role of PSTVd in decreasingsuch resistance.

Selected Reading

Querci, M., R.A. Owens, I. Bartolini,V. Lazarte, and L.F. Salazar. 1997.Evidence for heterologous encapsidationof potato spindle tuber viroid in particlesof potato leafroll virus. J. Gen. Virol.78:1207-1211.

(IP Program Report 1995-96 155

Progress in Identifying VirusesInfecting Andean Root and Tuber Crops

C. Lizarraga, M. Santa Cruz, and L.P. Salazar!

The first step in the control of any disease isthe isolation and study of the pathogen. Be­cause virus diseases can reduce yields inmany crops and are easily transmitted in veg­etative propagation, identifying viruses thatinfect Andean root and tuber crops (ARTC) isa major priority in the effort to produce plant­ing materials of high quality, and to facilitatethe international exchange of valuable virus­free germplasm.

The Andean tuber crops incl ude uIluco(Ullucus tuberosus Caldas), oca (Oxalistuberosa Mol.), and mashua (Tropaeolumtuberosum R. & P.). Two root crops arearracacha (Arracacia xanthorrhiza Bancroft)and mauka (Mirabilis expansa R. & PJ Virusesin these crops have not been well studied.

Previously, only four viruses were reportedinfecting ulluco: ullucus mosaic virus (UMV),ullucus virus C (UVC), papaya mosaic virus(PapMV-U), and tobacco mosaic virus (TMV­U); three infecting oca: potato black ringspotvirus (PBRV), arracacha B, and PapMV-O; andth ree infecting arracacha: arracacha A (AVA),arracacha B (AVB), and arracacha potyvirus1 (AP-1). Their effect on ARTC has not beendetermined.

Materials and Methods

Virus identificationStandard virological techniques applied

to studies of potato viruses were used. Viruseswere isolated by mechanical inoculation orgraft inoculation, or were insect-transmittedto indicator plants and identified by serologyusing antisera avai lable for known viruses.Purified preparations of the isolated vi ruses

1 CfP, Lima, Peru.

156 Program 3

were injected into rabbits to produce antiserafor detection and for determining serologicalrelationships to well-known plant viruses.

Virus effect on yieldTwo ulluco accessions, MH-290 and MH­

296, from the germplasm collection main­tained at CIP and freed of virus infection bythermotherapy and meristem culture wereprovided by C. Arbizu (CIP). The in vitroplants were multiplied by cuttings in thescreenhouse in CIP-Huancayo (3,200 mabove sea level) and the tubers were collected.

To study the effect of primary infection, thetubers were planted in October 1994 in CIP­Huancayo. The young ulluco plants weremechanically inoculated in December 1994with UMV, UVC, and PapMV-U individually,and with the three viruses simultaneously.Control plants were mock-inoculated withdistilled water. The tubers were harvested inJune 1995 and stored until October 1995,when the MH-290 tubers were planted in thesame field to study secondary infection.Tubers from MH-290 were harvested in June1996.

Results

Table 1 shows the viruses isolated and theones now known to infect five ARTC.

No significant differences (P~0.05) werefound for the yield of ulluco plants with pri­mary viral infection and the healthy control.Table 2 shows the effect of three different vi­ruses on the yield of ulluco plants (MH-290)with secondary viral infection in CIP­Huancayo. As expected, the combined infec­tion by the three viruses caused a higher yielddecrease.

Table 1. Viruses known to infect ulluco, oeo, mashua, arraeocha, and mauka, Clp, 1996.

Table 2. Average yields (kg) of ulluco plants MH·290 with secondary infection of three viruses, CIP·Huaneoyo,1996.

271038

Yield reductionb(%)First category tubers

10.5 b10.7 b14.5ab10.5 b1,6.0 a

viruses in ulluco and oca supports the premisethat plant viruses can adapt to new hosts sub·sequent to long-term associations. Althoughthe importance of these viruses in ulluco andoca is unknown, PLRV is the most importantvirus in potato. PLRV-infected ulluco plantsgrown near potato seed stocks could haveserious epidemiological implications, particu­larly because PLRV has a reported incidenceof 37% in ulluco.

elP Progrom Report 1995-96 157

19.1 be19.7 be24.2 ab16.7 e

26.9 a

Total yield'

(rop Vi ruses identified Viruses identified Viruses in process of

previously in this study identification

Ullueo UMV PLRV

UVC APLV

PapMV·U AVA

TMV

Oca PBRV PVT 0·2

AVB

PapMV·O

Mashua SoMV M·l, M·3, M·4, M·5

Arracacha AVA PBRV·A AV·3

AVBAp·1

Mauka Mir·1

UMVUVCPapMVUMV + UVC + PapMVHealthy control

Treatment

a. Inner rows of 66 plants. Means within (alumnsfollowed by the same letters ore not significantly different at the

P-sO.05Ievel.

b. Comporedwith healthy (ontroltotal yield.

Discussion

In the Andes, ulluco, oca, and potato are of­ten intercropped and the presence of potato

The reported incidence of viruses in ulluco,oca, and arracacha in the Andean region(Table 3) indicates the possible relative im­portance of the different vi ruses that infectARTC.

Table 3. Reported incidence of viruses in ulluco, ow, and arrowcha in the Andean region.

158 Program 3

5787853437443

0.20.2

226

2551

7

52

Reported incidence (%)

Selected Reading

Many viruses infect ARTC; determiningwhich ones cause major yield reductionsmust be a high priority in the continuation ofthis work. Information on viral incidence anddistribution has a collateral role in ascertain­ing the importance of viruses.

justify using resources in the production ofvirus-free materials. The same studies shouldbe done for all ARTC, beginning with the mosteconomically important ones.

Lizarraga, c., M. Santa Cruz, and U.Jayasinghe. 1996a. Detection of anisolate of Andean potato latent virus inulluco (Ullucus tuberosus Caldas). PlantDis. 80:344.

Lizarraga, c., M. Santa Cruz, and L.F.Salazar. 1996b. First report of potatoleafroll virus in ulluco (UllucustuberosusCaldas). Plant Dis. 80:344.

Salazar, L.F. 1996. Potato viruses and theircontrol. ClP, Lima, Peru. 226 p.

Virus

UMVUVC

PapMV-U

TMVPlRV

APtV

AVAPBRVAVB

PopMV-OAVAAVBAP-l

PBRV-AAV-3

(rop

UllucoUllucoUlluco

Ulluco

U/lucoU/luco

Ulluco

Oca

Oca

ArrocochoArrococha

Arrocacho

The practical impact of ARTC virus identi­fication studies is the production of virus-freeplanting materials that will allow farmers toobtain higher yields and reduce degenerationof cultivars. The results of field experimentsin Huancayo have shown that clean ullucoplanting materials can have higher yields thanplants secondarily infected with viruses. UMVand UVC have reported incidences of 7~%and 87%, respectively, and apparently are themost important viruses in ulluco since theycause yield reductions above 27%.

The antisera produced in these studies canbe used in the sensitive serological techniquecalled enzyme-linked immunosorbent assay(ELISA) to provide reliable virus detection forinstitutions involved in cleaning up ARTC andproducing healthy planting materials.

Conclusions

Although these results indicate that virus-freeulluco can have higher yields, further workmust be done in farmers' fields to confirm thisand to determine the rate of reinfection to

Fausto Cisneros t

1 Program Leader. ClP. Lima. Peru.2 Acronyms cited in this section can be found written outin the section Acronyms, p. 320.

In addition, the FAO's farmer field schoolmodel, developed for implementing IPM onrice, is being adopted by ClP's regional of­fice in Southeast Asia to manage sweetpotatopests. The objective is to improve analyticaland decision-making skills of farmers. Thisexperience is in the initial stage.

To develop our work along these premises,we follow a strategy that has five develop­mental phases: (1) pest assessment, (2) devel­opment of IPM components, (3) integrationof these components, (4) establishment of IPMpilot units in farmers' fields, and (5) large-scaleIPM implementation.

Pro

(IP Progrom Report 1995-96 159

and maintain. Finally, training activities andtraining materials are oriented toward improv­ing farmers' capacity to understand and betterselect the IPM options.

REPORT

Six premises guide the work of CIP's Inte­grated Pest Management (I PM) Programwithin the overall ecological context of IPMfor crop protection without affecting humanhealth and the environment. First, small- andmedium-size farmers with limited resourcesare defined as the clientele. Second, IPM re­search and implementation are considered acontinuum that culminates in farmers' fields.Third, IPM components are offered to farm­ers not as a technological package but as amenu of options appropriate to their situa­tions. Fourth, IPM is implemented in the broadercontext of integrated crop management in col­laboration with farmers' organizations, NARS2,and NGOs. Fifth, IPM programs are sustainableonly insofar as they are simple to implement

Integrated PestManagement

PROGRAM

Target Pests

Selected key pests of potato were the com­plex of potato tuber moths (PTM) that in­cluded the common PTM (Phthorimaeaopercu/ella), widely distributed in the warmerpotato-producing areas; the spotted orAndean PTM (Symmetrischema tangolias),present at mid-elevations in the Andean coun­tries; the Central American PTM (Teciasolanivora), which is rapidly spreading toSouth America; and the Andean weevil com­plex (APW), which includes Premnotrypesspp. and other related genera, in the highmountains (> 2,800 m) of the Andean region.These pests can cause damages above 50%in the field (APW) or in stores (PTM). Anotherselected key pest is the leafminer fly,Liriomyza huidobrensis, and related species.They are widespread and responsible for the

heavy use of insecticides in potato and othervegetable crops.

Weevils were the selected key pests forsweetpotato. The Asian species (Cylasformicarius) is the most serious pest ofsweetpotato in the Caribbean and South Asia.The African species (c. brunneus and C.puncticollis) that occur in sub-Saharan Africaare equally injurious.

Research Achievements

Progress in IPM for key pests under study isreported here in the IPM phases at which mostof the work was done during the report pe­riod, 1995-96. The economic importance ofeach pest was assessed before biological re­search started.

Development of IPM componentsIPM components in the developmental

phase are those for control of the African spe­cies of sweetpotato weevil in sub-SaharanAfrica, leafminer fly in Latin America and theCaribbean, and PTM in Morocco and Yemen.

Research on the African weevils was con­ducted in Uganda and included the study ofthe life cycles and seasonal history of the twospecies, the effects of cultural practices onweevi I damage, and the identification and

160 Program 4

synthesis of sex pheromones for both. Phero­mones may become a key IPM componentfor managing the weevils. These componentsare beginning to be tested in pilot units.

Research on leafminer flies included thestudy of the life cycle, the seasonal history,plant-insect interactions (with special atten­tion to the egg-extrusion phenomenon), de­velopment of resistant potato clones, the oc­currence and effectiveness of the complex ofnatural enemies, the selective effect of larvi­cides, and the effects of cultural practices.

In Morocco and Yemen, the developmentof IPM components for PTM concentrates onbiological control. In addition to using granu­losis virus (GV) and Bacillus thuringiensis(Bt),four parasitoids are being reared for releasein Yemen and Tunisia: Capidasama kaehleri,Oiadegma malliplum, Chelan us phtharimaea,and Orgilus lepidus.

Integration of IPM components intopilot unitsAfter several years of investigation, the

components for the management of SouthAmerican PTM and APW, and the commonPTM in northern Africa, have been integratedinto pilot units. In some areas, implementa­tion is already extending beyond the pilot unitboundaries.

Latin America and the Caribbean. In Peru,pilot units have been established in six farmcommunities: two in the south (Cusco) withthe participation of ARARIWA (an NGO) andINIA, three in the central mountains (Junin)with the participation of TALPUY (an NGO)and INIA, and two in the north (Cajamarca)with the participation of INIA.

Weevil damage in the north was reducedfrom an initial level of 60% to a current level of10%, and from 44% to 7-10% in the south. Theareas of influence of these pi lot units are in­creasing steadily as farmers of neighboring com­munities participate in field days when farmersin the pilot units explain their experiences.

The NGO CARE-Peru created an IPM pro­gram for the management of APW and PTM

with the financial support of USAID (1994­96) and the technical support of CIP. The pro­gram, called MIPANDES, proved very suc­cessful and benefited 3,200 peasant fami liesin the high mountains.

Similar pilot units have been establishedin Bolivia (at Mizque for PTM and at Kollanafor APW) with di rect participation ofPROINPA and IBTA. In Ecuador, pilot unitsare situated in Chimborazo and Cotopaxi withthe participation of INIAP. In Colombia, pilotunits at Ventaquemada and Motavita have thecollaboration of CORPOICA, the localUMATAs, the Secretaria de Agricultura, andSENA. These pilot units in the Andean coun­tries are supported financially by the Inter­American Development Bank.

Finally, in the Dominican Republic we es­tablished pilot units for PTM in Constanzawith the collaboration of MIP/JAD. Sprayingsfor PTM control have been reduced from sixper cropping season to only one.

Middle East and North Africa. Pilot unitsfor managing PTM in stores were establishedat 13 sites in Egypt to introduce the use ofGV and Bt as alternatives to the toxic insecti­cide fenitrothion, which has been officiallybanned for use on ware potatoes. Five sitesare producing GV and two are producing Bt.More than 250,000 pheromone traps are usedto monitor PTM populations in the field todetermine when to begin control measuresand to reduce pesticide use. Three govern-

ment agencies are involved in the program:PPRI, AGERI, and ARC.

Pilot units have been established in threemajor potato areas in Tunisia: Jendouba, CapBon, and Bizerte. They are demonstrating theefficiency of GV for PTM control as an alter­native to deltamethrin and malathion, whichare commonly used.

Large-Scale Implementation

A case of extraordinary growth of IPM withCIP's technical support is the managementof the sweetpotato weevil in Cuba. Damageto the Cuban sweetpotato crop had been heldto about 10%, with 10-12 sprayings a sea­son, when Cuba was obtaining insecticidesfrom the Soviet Union. But damage balloonedto about 50% when the insecticides were nolonger available, beginning in 1991-92.

In just three years (1993-96), the first twopilot units covering 230 ha in two provinces(Cienfuegos and Villa Clara) expanded toabout 10,000 ha in all 13 provinces of theisland. The Cuban organization INIVIT simul­taneously developed an active research pro­gram and an implementation campaign.Pheromone traps, predatory ants, the para­sitic fungus Beauveria bassiana, and strictcultural practices were the main componentsof the program. As a result, weevil damage isback down to 5-10%, without any use of in­secticides.

(IP Program Report 1995-96 161

Integrated Management for thePotato Tuber Moth in Pilot Units in theAndean Region and the Dominican Republic

M. Palacios and F. Cisneros!

The potato tuber moth complex is the mostdamaging pest of potato (So/anum tuberosum)under the warm and dry environments offields and stores. It is formed by three mainspecies: the common moth (Phtharimaeaapercu/ella), distributed worldwide; theAndean species (Symmetrischema tangalias),in the Andean valleys of Bolivia, Colombia,and Peru; and the Central American moth(Tecia sa/anivara), which has spread fromCentral America to Colombia, Ecuador, andVenezuela in recent years. Damage causedby these pests is around 30% in the field andabove 50% in stores when not controlled.

Farmers commonly use highly toxic chemi­cals to control tuber moths. As a result, pro­duction costs increase, farmer health is com­promised, moths develop resistance to mosttreatments, and in some places whiteflies(Aleyrodidae) appear as induced pests. Sur­veys show that farmers do not distinguish dif­ferent moth species or moth behavior in fieldsor in stores, nor do they understand the sea­sonal history of the pest. That lack of knowl­edge results in inadequate control methods.

CIP has developed a series of control meth­ods considered as integrated pest manage­ment (IPM) components. They are part of amenu of options being offered to farmers inpilot units distributed in the Andean coun­tries and the Dominican Republic.

Rationale of IPM Components

The life cycle and control measures of thecommon potato moth (P. apercu/ella) are wellknown. But little is known of S. tanga/ias. Our

1 CIP, Lima, Peru.

162 Program 4

studies have shown important differences be­tween these species in terms of duration oflife cycles (Table 1), seasonal history, behav­ior in fields and in stores, favorable ecologi­cal conditions, and control methods. In mostAndean valleys, P. apercu/ella and S.tanga/ias have three or four generations ayear. S. tanga/ias is not a pest at low altitudes,whereas P. apercu/ella develops 6 to 10 gen­erations a year. T. sa/anivara may have up tosix generations a year at medium to high alti­tudes.

Sources of infestation are potato stores andpotato fields, especially those fields wherepotato residue is allowed to remain after har­vest. Moths commonly move in both direc­tions. Field-infested tubers, or tubers infestedat harvest, carry initial infestations to stores.The various IPM components are designedto reduce pest movement between fields andstores and to lower larval and adult mothdensities. Pheromone traps to capture adu Itmales and the use of a Bacu/avirus to protectstored seed tubers are key IPM components.These measures have impressed farmers andprompted them to adopt other IPM measuresas well.

Field control measures duringcrop growthMeasures to protect the potato crop from

planting to harvest are primarily cultural con­trol methods.

Good soil preparation. Adequate soilpreparation not only ensures vigorous plantgrowth but also helps to destroy the remain­ing stages, mostly pupae, of the tuber mothbefore planting.

Boyo(oAntioquia

Symmetrischema

Timely harvesting. During the last phasesof the crop (tuber fi II ing and plant senes­cence), the infestation rate accelerates. De­laying harvest by 1 or 2 mo can increase dam­age by as much as 70%.

CIP Program Report 1995-96 163

Control measures at harvestThe two most important control measures

at harvest are protecting harvested tubers fromovipositing females and removing crop resi­dues from the field.

Pheromone traps. Commercial phero­mones are available for P. apercu/ella and T.solanivora. Mass trapping of male moths re­duces the probabilities of moth mating, thuscausing a drop in egg fertility. Pheromonetraps can reduce infestation by 50%.

moths to reach the potato tubers for oviposi­tion, and provide shelter for adult moths. Sprin­kling irrigation alone reduces damage by30%.

Peru

Frequent irrigation. Adequate wateringand cu Itivation prevent cracks from form­ing in the soil. Soil cracks allow female

PhtllOrill~aeaopercu/ella

High hilling. High hilling of growing plantsprotects the developing tubers from oviposit­ing females and reduces the possibility of lar­vae reaching the bulking tubers. High hillingcan reduce damage by 30%.

Deep planting. Covering tuber seed to adepth of 5-1 0 cm prevents female moths fromovipositing in seed tubers and keeps larvaefrom migrating to tubers from infestedaboveground sprouts. Neonate larvae of S.tango/ias can burrow to a depth of 5 cm; thoseof P. opercu/ella as much as 10 cm to the seedtubers.

Timely planting. Based on seasonal oc­currence studies, optimum planting dateswere determined to coincide with lower tem­peratures and the onset of rains. Farmers whoplant in the dry period face high moth in­festations.

Table 1. Life cyde in days for the three species of the potato tuber moth complex under conditions of pilot units inPeru, Colombia, and the Dominican Republic, 1996.

Table 2. Number of moths emerged per hectare' from harvest residues (tubers and stems) and volunteer plants.Pilot units, Peru and Colombia, 1996.

Tubers

481,000

Volunteer plants

Moth larvae (no./ha)

Stems

118,000

may result in infestation of the entire store inas Iittle as 4 mo.

Repellent plants. The foliage of someplants, rich in essential oils, such as Euca/yp­tus spp., Lantana camara, and the native spe­cies Schinus molle and Minthostachys spp.,repels potato moths. The leaves are driedunder shade, crushed, and then used to coverthe stored tubers. On the average, protectedtubers are 80% less damaged than nontreatedtubers.

Using Baculovirus. A dust formulation ofBacu/ovirus phthorimaea, containing 20 dis­eased larvae/kg at a dose of 5 kglt tubers, isthe most effective insecticide against P.opercu/ella. Protection is somewhat lower inthe case of the other two moth species. Tu­bers should be treated before larval infesta­tion begins.

Pheromone traps. Commercial phero­mones disrupt mating of P. opercu/ella and T.so/anivora during storage. Tubers stored withpheromone traps are about 95% less infestedthan the control stores.

Diffused-light stores. Potatoes stored indiffused light are generally about 70% lessinfested than those stored in the dark. Illumi­nation results in greening of the tubers (withglycoalkaloid formation), which is unfavor­able for the moth. In addition, the arrange­ment of tubers in diffused-light stores facili­tates the periodic elimination of damagedtubers.

49,00043,00032,000

S. tango/ias (Peru)P. operwlella (Peru)T. solanivora (Colombia}

a. Sampling in pilat units (25 samples of 1m2 each)

Measures to avoid damage in storesProtecting tubers in stores can reduce moth

damage by 70% to 95%.

Destroying harvest residues. P. opercu/ellaand, to a larger extent, S. tango/ias pupate intubers and dry stems left in the field. Mothsfrom these pupae infest the crop the follow­ing season (Table 2). Also, tubers left in thefield become volunteer plants in the rotationcrop. For these reasons, all harvest residuesmust be destroyed.

Covering tubers. Female moths becomeactive in the evening and most eggs are laidat that time. Harvested tubers should not re­main exposed to ovipositing females over­night. If they cannot be stored immediately,tubers shou Id at least be covered; otherwisethe infestation level could reach 60% withina few days.

Storing healthy tubers. On Iy healthy tubersshould be stored. Infested tubers should beburied under at least 10 cm of soil.

Cleaning stores. Cleaning floors, walls,and ceilings of rustic stores before storinghealthy tubers destroys pupae and other lifestages of the moth.

Storing healthy tubers. Tubers should besorted and infested ones discarded before stor­ing. Tubers exposed to moth ovipositionshould not be stored, as eggs are commonlyoverlooked during sorting. Storing infestedtubers or those that have been exposed tomoth oviposition along with healthy tubers

164 Progrom4

(IP Program Report 1995-96 165

Potato

A SON DDJFMAMJ

Urquillos. Potato is grown year-round inUrquillos. During the rainy season, potatoesare grown at elevations of 3,600-3,800 m. Inthe dry season, they are grown under irriga­tion at lower elevations (2,800 m) where thecrop is stored under constant pest pressure.The dominant species is S. tanga/ias, althoughP. apercu/ella is also present (Figure 1). Thepest problem is most serious in stores. Prac-

II! P. apercu/ella it S. tanga/ias I

Pilot units in PeruTwo pilot units have been established in

Peru: one in the southern community ofUrquillos, Cusco; and one in central Peru atCarhuapaccha, Huancayo. In those areas, twospecies of moths occur: P. apercu/ella in thewarmer valleys, and at higher altitudes S.tanga/ias, which is rapidly increasing in im­portance. No commercial sex pheromone isavailable for the control of S. tanga/ias. Themost important biological control agent is aBacu/avirus.

ClP set up IPM pilot units at two sites inPeru and Colombia in 1995 and one site inthe Dominican Republic in 1993. The IPMcomponents adopted by farmers in the pilotunits and the results they obtained are re­ported here.

NDJ FMAM JJAS

1 Potato 1Vegetablel 1 Potato 1 Vegetable 1

I Sefore.IP'M I ~I===::;=::;===""j--"P==M==irn=p=le=l11=e:;;:;;ht:!"'a-uo-n"!:;:;;:;;=::;===:::::!'

1994 ......1 --'-19:...:9...;:.5 ---' 1996

Month

600 r-----------------------------,

500 +--------------------------1

400 11----------------------------1

300 Iir-ir--+---------------------------j

200

100

Training and field days are essential in thepilot units. They are designed to motivate alllocal stakeholders (including farmers), tech­nicians, rural schoolteachers, university stu­dents, and community authorities to ensurethe stabi lity of the program. ClP provides tech­nical support, participates in training, andprovides basic instructional materials.

Figure 1. Pototo tuber moth field populotions in two consecutive yeors showing the effect of IPM implemento­tion in Urquillos, (usco, Peru.

Selection of Pilot Units

Moths (no./trap/wk)

The following activities take place in thepilot unit: evaluation of the problem, trainingoffarmers and local counterparts, implemen­tation of IPM components, adaptive adjust­ments of components, and identification ofnew research opportunities.

IPM components are tested in the field for fi­nal adjustments and evaluation of farmers'acceptance. That is done in pilot units of par­ticipating farmers who perceive the impor­tance of the pest and are interested in tryi ngnew methods for its control. The participa­tion of governmental agencies and nongov­ernmental organizations (NGOs) is crucial,because the pi lot un it is considered as a dem­onstration area for IPM implementation at thenational level.

tices adopted by farmers (largely by womenof the community) are cleaning of stores anduse of repellent plants and pheromone trapsagainst P. opercu/ella. Cleaning alone re­duced infestation in rustic stores to only 10%of that experienced previously. Field practicesadopted are deep planting, high hilling, irri­gatio"n, and timely harvest.

Before the IPM program began in 1994,average damage in stores was 65% despitethe use of highly toxic insecticides such asparathion. In 1996, average damage for farm­ers participating in the IPM program was 3.4%(0-12%), whereas other farmers experienced40-80% damage.

Farmers in Urquillos have formed an IPMcommittee to expand the use of IPM in thearea, and the Farmers Federation of Cusconow promotes IPM.

Carhuapaccha. Potato prod uction inCarhuapaccha is commercially oriented andinsecticide use is intensive. Potato is pro­duced at the higher elevations of the com­munity (3,160-3,800 m). Irrigation is avail­able at lower elevations and farmers produceother vegetables. Storage is limited to seedtubers and tubers for self-consumption. Thebulk of production is sold in the local mar­ket.

Practices adopted in stores to controlS.tango/ias were cleaning stores, sorting, useof Bacu/ovirus to protect tuber seed, and re­pellent plants to protect potatoes for homeuse.

About 50% of the tubers were infested instores before the program started in 1995;damage in 1996 was reduced to 10%,whereas damage on neighboring farmsranged from 65% to 85%.

Pilot units in ColombiaThe most damaging pests of potato in Co­

lombia are the Andean potato weevil(Premnotrypes spp.) and T. so/anivora, whichwas introduced from Venezuela to Colombiain 1985. At first it was restricted to the Nortede Santander Department, but by 1996 it had

166 Progrom 4

spread to the south of Colombia (Narino De­partment) close to Ecuador. The aggressive­ness of this pest, which infests tubers but notabovegrou nd p Iant parts, created pan icamong farmers, who then started heavy spray­ing of fields and stores.

ClP's assistance in dealing with the pestwas requested in 1994. A work program ori­ented toward implementing IPM began in twopilot units, one in EI Santuario, Antioquia, andthe other in Ventaquemada, Boyaca.

EI Santuario. The Corporaci6n dellnstitutoColombiano Agropecuario (CORPOICA) wasCIP's counterpart, leading in the implemen­tation of OP recommendations for the area.The first step was an intensive campaign toteach farmers and technicians how to recog­nize this new pest and its life cycle, behav­ior, and movements. The effectiveness of sexpheromone trapping was demonstrated, theeffectiveness of Bacu/ovirus was tested, andtraining materials were produced.

Farmers adopted the following practices:pheromone traps in fields and stores, use ofBacillus thuringiensis (Bt) and Bacu/avirus instores as alternatives to toxic insecticides, useof healthy seed, high hilling, timely harvest,and clean ing stores.

In 1994, 50% of the area planted to po­tato was infested with T. so/anivora. Thirtypercent of tubers were infested at harvest. Instores, 100% tuber infestation was common.In 1996, the average number of infested tu­bers at harvest for the whole Antioquia De­partment, including the pilot units and differ­ent levels of IPM influence, dropped to 4.4%(0-43%), and average damage in stores was11.4% (0-37%). During the last season, about23,300 pheromone traps were used.

Ventaquemada. Until 1993, the only po­tato tuber moth species reported damagingpotato was P. apercu/ella. Average infestedtubers at harvest was low, 3.5%, because ofthe intensive use of insecticides (12 spraysper season). In 1994, the presence of T.so/anivora was confirmed in Boyaca andheavy losses were reported-56% infested

(IP Program Report 1995-96 167

20

10

40

Sept

Conventional ---+ 30

Aug

Field populations of the moth have beenreduced from an initial catch of 136 moths/trap/week to 19. In 1996, infested tubers atharvest in IPM fields were 0.1 % without the

Damaged tubers (%)

Farmers adopted planting healthy tubers,deep planting, sex pheromone trapping, fre­quent irrigation, timely harvest, and the useof Bt. Action thresholds were established fordetermining the timing of Bt applications.

The local semiprivate organizationPrograma Nacional de Manejo Integrado dePlagas (MIP) started a program to reduce theexcessive use of insecticides in 1991. In 1993,ClP coordinated a program with MIP to imple­ment IPM on potato.

Pilot unit in the Dominican RepublicIn the Dominican Republic, the main po­

tato-producing area (85% of national produc­tion) is the high Constanza plateau, whereother vegetables are also cultivated. Intensivespraying is a characteristic of the area. Six toeight sprays per season (at 6-8-day intervals)to control P. apercu/ella are common. Underheavier infestations, potato fields are sprayedat 3-4-day intervals.

JUly

Month

I 0 Inside plot II Outside plot I

June

Total capture5,422

MayApr

o

500

1,500 1------------------------

2,000 ,...-------------------------··50

The Secretaria de Agricultura de Boyacahas started producing Bacu/ovirus to copewith the increasing demand.

Figure 2. Population variation of Teda solanivora in IPM plots and percentage of damaged tubers at harvest.Ventaquemada, Boyaca, Colombia, 1996.

1,000

Moths (no./plotlwk)

Farmers that adopted IPM measures hadonly 1% infested tubers at harvest, whereasother farmers had 40% damage despite theuse of insecticides (Figure 2). The selling priceof IPM potato was 35% higher than that ofinsecticide-treated potato. A total of 14,800pheromone traps were used in 1995 over anarea of 925 ha.

In fields, farmers adopted destruction ofcrop residues, sex pheromone trapping, highhilling, and timely harvest. In stores, theyadopted cleaning, use of Bacu/ovirus to pro­tect tuber seed, pheromone traps, and, to alimited extent, diffused-light stores.

tubers at harvest. The most affected munici­pality was Ventaquemada. A program devel­oped included research on seasonal occur­rence, studies on the effectiveness ofBacu/avirus and sex pheromone trapping, andthe implementation of sanitary measures. Anintense training program was developed forfarmers and technicians.

use of insecticides. Fields with conventionalcontrol programs had 15% infested tubers.Average yield in MIP fields was 13.8 t/ha com­pared with 8.9 t/ha in fields where conven­tional control practices prevai led.

Conclusions

The implementation of IPM for the manage­ment of the potato tuber moth in pilot unitsin Peru, Colombia, and the Dominican Re­public has demonstrated that ClP's approachis viable, well accepted by farmers, and cata­lytic for the participation of local institutions,both governmental and NCO. Net benefitswere evident: pest damage decreased signifi­cantly and the use of insecticides dropped toa minimum.

The acceptance of IPM by farmers was duenot only to the effective components devel­oped by CIP's program but also to the ad­equate training programs for farmers, techni-

168 Progrom 4

cians, and other stakeholders, and the par­ticipation of local institutions. In this case, atotal of 9,728 persons received some kind oftraining in 1,207 activities, most of them car­ried out by local institutions.

Technologies such as mass trapping withsex pheromones and the use of Baculovirushave stimulated the interest of various privateand official organizations in commerciallyproducing these biological control productsto make them widely available to farmers.

In Peru, the participation of CARE-Peru, anNCO, expanded the influence of the IPM pi­lot units to 3,500 families in the poorest ar­eas of the mountains. This successful programis now being extended to 10,000 families bya collaborative effort of CARE and thePrograma Nacional de Manejo de CuencasHidrograficas y Conservaci6n de Suelos(PRONAMACHCS), a government-relatedorganization.

(IP Program Report 1995-96 169

Farmers close to cities are more commer­cially oriented and use toxic insecticides(carbofuran, parathion, aldicarb, andmethamidophos) to control weevils. Despite

ARGENTINA

Most inhabitants of the high Andes arepoor peasants, with an extremely low levelof literacy, who receive little, if any, techni­cal assistance. They accept the damagecaused by weevils (commonly above 50%)as inevitable and occasionally abandon fieldsbecause of high infestations. The division ofland into small units has rendered impracti­cal the old system of large communal landrotations that was once used to efficientlycontrol weevils and other pests and diseases.

Figure 1. Distribution of the main species of Andean potato weevil.

Premnotrypes suturicallus~

1 CIP, Lima, Peru.

Premnotrypes latithorax

Potato (Solanum spp.) that is cultivated in thehigh Andean mountains (2,500-4,750 m) ofBolivia, Peru, Ecuador, Colombia, and Ven­ezuela is severely damaged by the Andeanpotato weevil or white grub. This is a com­plex of species, most of them belonging tothe genus Premnotrypes (Curculionidae). Thedominant species are P. latithorax (Pierce) inBolivia and southern Peru, P. suturicallusKuschel in central Peru, and P. vorax(Hustache) in northern Peru, Ecuador, Colom­bia, and Venezuela (Figure 1). Species of othergenera, Rhigopsidius tucumanus Heller andPhyrdenus muriceus Germar, are largely re­stricted to Bolivia.

Integrated Management forAndean Potato Weevils in Pilot Units

J. Alcazar and F. Cisneros 1

170 Program 4

835

110179424101162

Sources of infestation are abandoned po­tato fields, fields harvested the previous year,places where potatoes were piled up duringharvest and sorting, rustic stores, and volun­teer plants in rotation crops. Most controlmeasures aim at destroying the overwinter­ing population, interrupting migration of theweevil to new fields, and reducing the wee­vil population in infested fields.

scattered distribution in the field. Other im­portant considerations were: all potato culti­vars are susceptible to weevil attack; the wee­vil invades potato fields by crawling fromoverwintering places because it is unable tofly.

Reducing weevil infestation in the fieldThere are several ways of reducing in-field

populations of potato weevil. They includeearly planting and use of early-maturing va­rieties, timely harvest, use of healthy tubers,handpicking adult weevils from the crop, anddestroying volunteer potato plants in rotationfields.

Early planting. Emergence of overwinter­ing adults lasts 8-14 wk and coincides with

the use of insecticides, 20-30% tuber infesta­tion is common. Although all farmers are fa­miliar with the larvae that bore into tubers,they know little else about the insect, includ­ing its life cycle and seasonal history, whichwould help them improve their pest controlpractices.

Rationale of IPM Components

The three common species of weevils havesimilar life cycles (Table 1) (one generation ayear, except for P. vorax, which presents twogenerations in some parts of Ecuador andColombia), behavior, and seasonal history(Figure 2).

Research conducted on these charactersled to the development of a series of controlmeasures, most of which could be includedas components in integrated pest manage­ment (IPM).

The absence of parasitoids, limited preda­tors, and only a single pathogen (Beauveriabrongniartii (Saccardo) Petch) made it clearthat cultural practices would be major con­trol components. Even the pathogen had a

Table 1. Life cycles of the three most injurious species of Andean potato weevils in (ajamarca (Premnofrypesvorax), Huancoyo (P. sUfuricallus), and Urubamba (P. lofifhorax), Peru.

o 0Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

• prepupae (%)

III immigration to potato field

Handpicking weevils. Adu It weevi Is in thepotato field become active in the evening;they climb the foliage for feeding and mat­ing. They can easily be captured by shakingthe foliage over any container. Farmers havereadily accepted this practic:e. Collectingweevils six times in a growing season reduceddamage by 34% (Table 2).

which results in poor stand establishment.Planting seed that had been bored by theAndean weevi I reduced yield by 31 % com­pared with planting noninfested seed (Table 2).

Destroying volunteer plants. Volunteerpotato plants in rotation fields are importantsources of weevil infestation and should bedestroyed as early as possible. Initially, somefarmers were reluctant to accept this practicebecause they could harvest some early pota­toes from volunteer plants. But more than30,000 weevils infested 6,500 volunteerplants/ha in a rotation field in Huancayo.

CIP Program Report 1995-96 171

Months

III pupae (%)

III oviposition

Weevils/1-m trap oreggs/female (%)

50 100

40 80

30 60

20 40

10 20

III overwintering adults (%)

o tuber infestation (%)

III adult emergence

Timely harvest. Delayed harvest extendsexposure of tubers to weevil infestation, al­though farmers sometimes delay harvest inthe hope of getting higher prices. Occasion­ally, early harvesting is recommended. A de­lay of 10 d in harvest resulted in an increasein tuber damage from 6.8% to 29.5% in onefield check.

Healthy planting material. In general,healthy tuber seed favors vigorous growth ofpotato plants. In particular, seed tubers dam­aged by Andean potato weevils rot readily,

the rainy season. Females lay eggs for 12-14wk. As more adults emerge, there is a con­tinuous increase in the number of females thatfind later plantings as ovipositing places.Early-planted fields are 4-5 times less infestedthan those planted late. This measure reducedweevil infestation and damage by 82.2%(Table 2). Early-maturing varieties are lessexposed to weevil infestation than late vari­eties and accomplish the same result as earlyplanting.

Figure 2. Seasonal history of the Andean potato weevil (Premnotrypes latithorax) in Urubamba, Peru. Averageof two years (1994-96).

Table 2. Experimental results showing the benefits of measures recommended to reduce weevil infestation anddamage' (experiments conducted in (useD and Huancayo, Peru), 1993-96.

Handpicking weeeviis (none)

D. Expressed as percentage of infested tubers at harvest.

77.0

82.2

31.3

34.1

Decrease in

damage (%)

3.2%18.0%6.8%

29.5%9.6 MT/ha6.6 MT/ha

23.8%36.1%

Tuber damage (%)

or yield (MT/ha)

Diffused-light stores. Seed tubers kept indiffused-light stores maintain better quality.Because the tubers are not in contact withthe soil, the larvae abandoning the tubers canbe destroyed or fed to chickens.

Ground sheeting. At harvest, many full­grown larvae abandon the tubers and dig intothe soil to pupate. Larvae can be interceptedon their way to the soil by barriers of plasticsheets or other materials.

Reducing overwintering populationsMeasures to reduce overwintering weevil

populations can be carried out in the field orin stores (Table 4). Harvested fields are win­ter-plowed to destroy larvae that move fromtuber to soil. Breaking the soil where pota­toes were piled at harvest or for sorting alsodestroys underground larvae and pupae.Plowing abandoned fields is effective in de­stroying overwintering insect stages.

Winter plowing. Many larvae reach ma­turity before harvest and leave the tubers tooverwinter underground as pupae. Most ofthese pupae are destroyed by plowing thefield 2 or 3 mo after harvest. At least 50% ofthe larvae and pupae in the soil are destroyedwhen plowing is done with oxen. Chickenshelp destroy exposed larvae and pupae.

Check

Late planting (December)

Delayed ha rvest (20 April)

Infested tuber seed

Measure

Early planting (October)

Healthy tuber seed

Handpicking weevils (6 times)

Timely harvest (1 0April)

Barriers. Migratory weevils can be inter­cepted by digging field peripheral trenchesand capturing or killing them with insecti­cides, or by simply spraying a 3-m-wide bandof insecticide around the perimeter of thefield. Bordering fields with nonhost plants alsodisrupts the migratory process, and is prefer­able to chemical control where it can be prac­ticed. Table 3 shows the reduction in tuberdamage resulting from these practices.

Interrupting adult migration andlarval movementBecause adult weevils cannot fly, physi­

cal barriers effectively halt their migrationfrom field to field as do peripheral trenches,which allow migrating weevils to be captured.Larval movement from tuber to soil can beprevented by using plastic sheets at harvestand sorting or storing tubers in diffused-lightstores. Weevil larvae and pupae are often fedto ch ickens.

Shelter traps. Straw bundles, pieces of si­sal, or plastic sheets and other materials pro­vide shelter to weevils during the day whenthey can be captured. An alternative is to putinsecticides in the shelter. Better effects areobtained with insecticide-treated potato fo­liage placed in new potato fields. This prac­tice has been studied and well accepted inEcuador.

172 Program 4

23,

weevils/m of

6.7% vs. 19.

23,430 weevils (stores: 70 m2)

12.7%vs. 35.0% (check)

Intercepted papulatian/damage at harvest

ity Huatata

X

X

X

Plant barriersBorder sprays X X X

X X X

X

X X X

X

X XX

(IP Progrom Report 1995-96 173

re

Sheets at pre-store

sorting

Table 4. Preferred adoption (> 50% of target population) of IPM components by communities integrating IPMpilot units in Peru.

Table 3. Experimental results shawing the benefits of measures recommended to intercept migration of adultweevils and movement of larvae from tubers to the soil (average of experiments conducted in Urubambaand Huancoyo, Peru), 1993-96.

Abandoned fields are another major sourceof weevil reproduction and migration. Dur­ing winter, abandoned fields should beplowed at least twice.

Breaking the soil. When recently har­vested potatoes are not piled on sheets, largenumbers of larvae dig into the soil to pupate.The soil should be broken up in winter todestroy underground larvae and pupae. Morethan 90% of overwintering larvae are de­stroyed by this practice.

The parasitic fungus Beauveria brongniartiican be used to control larvae digging into thefloor of rustic stores. Mortality surpasses 80%.

Selecting Sites as IPM Pilot Units

Selecting the pilot unit is a crucial step in theimplementation of IPM. Here, the scientificdevelopment of IPM components meets thereal world of farmers-their risks, interests,economics, culture, cropping practices, andother factors that can determine the successor failure of the program. This precedes thelarge-scale implementation of IPM. In addi­tion to farmers, other key players are mem­bers of national agricultural research systems(NARS), nongovernmental organizations(NGOs), and other groups that will eventu­ally assume responsibility for expanding theprogram.

Two conditions had to be met for a com­munity to qualify as a pilot unit. The first wasthat farmers had to recognize the Andeanpotato weevi I as the most serious pest prob­lem. Second, there had to be a nucleus offarmers willing to try new methods to reducetuber damage and insecticide use.

Selected sites in Peru were Huatata,Urubamba Province; Chuamba andCasabamba, Huancayo Province; Aymara,Tayacaja Province; and Chilimpampa,Cajamarca Province. Four other sites werechosen outside Peru: La Paz Department inBolivia, Cotopaxi and Chimborazo provincesin Ecuador, and Boyaca Department in Co­lombia.

174 Program 4

Description of Main Pilot Units

With pilot units, ClP's IPM staff works closelywith farmers to evaluate the effectiveness ofpractices and the reaction of farmers to theIPM program. Farmers from neighboring com­munities, directly or by influence of local or­ganizations, commonly adopt practices theyhave seen demonstrated in the pilot units.These ancillary "areas of influence" providesome assistance in diffusing /PM concepts.

Farmers in the pilot units were trained onthe basics of the program to make them fullyaware of the options presented as IPM com­ponents. We organized short courses, fielddays, and workshops and produced trainingmaterials such as bulletins, posters, samples,sl ide sets, flip charts, and videos. Train ing wasextended to selected collaborators from sev­eral institutions who would take over fieldwork in the large-scale implementation phase.In a four-year period (1992-96), 3,984 farm­ers took part in field days in Junin, 2,058 heardtalks in Cajamarca, 1,627 participated inweevi I-picking contests in Cusco, and 1,835received short courses in Cajamarca.

Pilot units in PeruPilot units in Peru were selected to opti­

mize the evaluation of the IPM componentsunder different conditions.

• In the south (Urubamba), with the weevilspecies P. latithorax and traditionally ori­ented potato production.

• In central Peru, with P. suturicallus, in morecommercially oriented Huancayo and inmore traditionally oriented Tayacaja.

• In the north (Cajamarca), with P. voraxandless traditional varieties.

Huatata. Practices that have more than50% acceptance are timely harvest, use ofchickens as predators, breaking the soil orusing sheeting, handpicking weevils, destroy­ing volunteer plants, and using B. brongniartiiin rustic stores. Although some farmers havestopped using insecticides, many others still useone spray of a "safe IPM compatible" product,as it is described by insecticide dealers.

Before the program began in 1990 anddespite heavy use of insecticides, damage (%of infested tubers at harvest) was 44%. In1996, damage varied from 8% to 12%.

Chilimpampa. Most farmers have adoptedhandpicking weevils, timely harvest, use oftarwi or barley as non host field edge barri­ers, use of sheeting at harvest and sorting,winter plowing, use of chickens as predators,breaking of soil, and shade traps. Farmershave adopted anywhere from three to fivepractices.

When the program began in 1993, farm­ers had an average damage of 61 % of infestedtubers at havest. During the 1996 harvest,damage dropped to 13%. Farmers in the com­munity have a fairly good knowledge of thebiology and seasonal history of the pest andits control.

Aymara. Most farmers adopted the use ofsheeting at harvest, eliminating volunteerplants, timely harvest, use of chickens aspredators, winter plowing, and border spray­ing. Some practices such as destroying vol­unteer plants and handpicking weevils areorganized and conducted by the whole com­munity. Damage in 1993 was 39% of tubersat harvest despite the use of insecticides.During 1996, damaged ranged from 15% to20%.

Casabamba and Chuamba. Most farmersadopted handpicking of weevils, use of sheet­ing at harvest, timely harvest, high hilling, useof diffused-light stores, use of chickens aspredators, destroying volunteer plants, win­ter plowing, and border spraying. Damage inCasabamba decreased from 45% in 1994 to19% in 1996. In Chuamba, the program wasadopted only in 1996. Damage in demonstra­tion fields was 13%, whereas damage in therest of the area was 41 %.

Pilot units in Bolivia, Colombia,and EcuadorThe Peruvian experience was extended to

Bolivia, Colombia, and Ecuador followingsimilar criteria in the selection of the pilotunits. In this respect, PROINPA-IBTA,

CORPOICA, and FORTIPAPA-INIAP playedkey roles.

Bolivia. Farmers adopted field bordertrenches, winter soil breaking, use of chick­ens as predators, timely harvest, use of sheet­ing at harvest, border spraying, and destroy­ing volunteer plants. Infected tubers at har­vest in the 1994-95 cropping season reached44%. This was reduced to 30% in 1996, thefirst year of the program.

Ecuador. Most farmers have adopted theuse of shelter-treated traps, treated potatoplant-baits, crop rotation, destruction of vol­unteer plants, breaking the soil in sorting andstoring places, and selective chemicals(Orthene instead of carbofuran). Damage atharvest in IPM fields in 1996 varied from 6%to 22%; in nonparticipating fields, damagevaried from 33% to 97%.

Colombia. Farmers in 1995-96 concen­trated on reducing spraying, which is com­mon in the area. Instead of broadcast treat­ments, spraying was limited to edge bandswith similar results. Complementary practicesinclude destroying crop residues and moni­toring the weevil population near field edges.More recently, diffused-light stores are beingadopted to reduce damage from the weeviland the potato tuber moth Tecia solanivora.

At the beginning of the program, damagedtubers at harvest varied from 20% to 60%,depending on the intensity of chemical use.During 1996, fields within the program had2-12% damage, whereas fields with tradi­tional (mostly chemical) protection sustained8.5% to 60% damage.

Conclusions

Working with farmers in the high Andes requiresmore resources than ClP has available. At thesame time, there are governmental organiza­tions and NGOs in the area working to improvefarmers' productivity and general welfare. Theseinstitutions benefit by taking advantage of ex­isting technologies such as those developed byCIP for the management of the Andean potatoweevil. ClP in turn gains valuable research part-

OP Program Report 1995-96 175

176 Progrom 4

ture of the year-to-year variations in climateand pest incidence. This time will also allowus to consolidate the training of personnelfrom collaborating institutions that will beinvolved in the large-scale implementation ofIPM in areas where the Andean weevil is thekey pest.

Future research should focus on the man­agement of the fleabeetle Epitrix spp., whichis the second most important pest for potatoin the high Andes.

HuarazAijaReeuay (APW-PTM)

Huaneayo (APW-PTM)

Tayaeaja (APW} '---------'

Urubamba (APW-PTM)

OtuzeoJulesn (APW-PTM)

t Caiam~rea ISan PabloContumaza(APW-PTM)

APW: Andean potato weevilPTM: Potato tuber mothc::::::::J CIP supervised pilot units

PunoLampaSan RomanChueuitoYunguyo (APW) -----../

ners. Figure 3 shows CIP cooperators in theAndean region IPM program.

Most of the research needed to developIPM components for the PremnotrypesAndean potato weevils has been completed.There still remains the task of improving theuse of the parasitic fungus B. brongniartii anddeveloping measures for the control ofPhyrdenus and Rhigopsidius weevils whosebehavior differs from that of the other species.

Two or three more years of implementa­tion in the pilot units will give a clearer pic-

Figure 3. Integroted monogement of pototo pests in the Andeon region; loeotion (provinces) of pilot units.Colloboroting institutions ore Corporocion Colombiono de Investigocion Agropecuorio (CORPOICA),

Colombio; Instituto Nocionol Autonomo de Investigociones Agropecuorios (INIAP), Fortolecimiento de 10 Investigociony Produccion de Semillo de Popo en el Ecuodor (FORTIPAPA), Ecuodor; Instituto Boliviono de Tecnologio Agropecuorio(IBTA), Progromo de Investigocion de 10 Popo (PROINPA), Bolivio; Instituto Nocionol de Investigocion Agrorio (INIA),Grupo de Investigocion y de Desorrollo de 10 Ciencio Andino (TALPUY), CARE-Peru, ond Asociocion ARARIWA, Peru.

Developing IPM Components forLeafminer Fly in the Canete Valleyof Peru

N. Mujica and F. Cisneros1

The leafminer fly Liriomyza huidobrensisBlanchard is a serious pest of potato in manyplaces where potato is intensively cultivated.It is the most damaging pest in the coastalvalleys of Peru. Farmers in the Canete valleytry to control the pest by spraying 8-13 timesper season on a calendar basis. Insecticidesare the highest input cost (an average ofUS$600/ha) followed by fertilizer, fungicides,and manure. Noncontrolled infestations com­monly reduce yields by 50% or more.

In most places, leafminer flies have devel­oped significant levels of resistance to mostcarbamate, organophosphate, and pyrethroidinsecticides commonly used to kill adult flies.Rapid development of resistance and natu­rally occurring pest tolerance of many chemi­cals seem to be a generalized characteristicof L. huidobrensis. For these reasons, this spe­cies is commonly regarded as the most diffi­cult-to-killieafminer fly worldwide.

Frequent spraying in the coast of Peru hascreated additional problems such as severeinfestations of the white mite, Poly­phagotarsonemus latus (Banks), and thebudmidge, Prodiplosis longifila (Gagne).

Although native to the neotropics (infesta­tions are reported from Peru, Chi Ie, Argen­tina, Brazil, Central America, and Mexico),L. huidobrensis is rapidly spreading to otherareas where it readi Iy becomes a serious pest.It has recently been reported in Europe, sev­eral countries in Africa, and in Indonesia,Malaysia, and Israel.

1 CIP, Lima, Peru.

Life Cycle, Behavior, andSeasonal Abundance

The life cycle of the leafminer fly has beenstudied in the laboratory and the greenhousein Lima and Canete, using potato and beanas host plants. We have determined the du­ration of each developmental stage, oviposi­tion capacity, sex ratio, and adult longevity.Table 1 summarizes this information.

The adult female punctures the upper orlower surfaces of tender leaves with her ovi­positor, or egg-laying structure. Males andfemales feed on the exudates produced bythe lesions. Simi lar punctures are used by thefemale to encrust the egg in the leaf tissue.

Neonate larvae start tunneling through thechloroplast-containing spongy mesophyilleaflayer. Tunnels increase in diameter as the larvagrows. Although any part of the leaf bladecan be tunneled, full-grown larvae tend tostay close to the midrib. Full-grown larvaepupate inside barrel-shaped puparia on theleaf surface. Puparia fall to the ground andremain there until the emergence of the adultflies. Mating occurs 2-3 days after emergence.

There is a clear seasonal variation of flypopulation densities in the Canete valleywhere early potato plantings take place inMarch (end of summer) and harvest of lateplantings occurs in December (end of spring).Higher population densities occur during thewinter months-June, July, August, and Sep­tember. Fly populations are low during thewarm months (November-March).

Within a given field, the fly population isassociated with the phenology of the potato

[IP Progrom Report 1995-96 177

Table 1. life cycle (doys) of the leofminer fly Liriomyzo huidobrensis under screen house ombient conditions,(onete, Peru, 1996.

In a study to determine the role of weedsas sources of leafminer fly infestations and asrefuges of parasitoids, 24 weed species wereidentified corresponding to 13 families. Sig­nificant levels of fly larval parasitism (40-70%)were found in Trianthema portulacastrum(Aizoaceae), Stachys arvensis (Lamiaceae),Chenopodium murale and C. album(Chenopodiaceae), Datura stramonium(Solanaceae), Bidens pilosa and Galinsogaparviflora (Asteraceae), Diplotaxis muratis(Brasicaceae), Malva parviflora (Malvaceae),Ricinus communis (Euphorbiaceae), andStellaria media (Caryophylaceae). The iden­tification of the leafminerflies and their para­sitoids at the species level is under way.

4 30 15.7 3 28 25.93 6 4.7 2 4 3.0

August (winter) October (spring)min mox ov min max av

3 4 3.6 3 4 3.3

3 3 3.0 3 4 3.13 3 3.0 2 3 2.54 4 4.0 3 3 3.0

14 18 16.3 12 17 14.0

27 32 29.9 23 31 25.9

31 62 45.6 26 59 39.930 38 34.6 25 35 17.0

40 285 116.6 n 704 lOlA

plant. For example, there is a relatively slowincrease during the vegetative growth and arapid and sustainable increase during flow­ering, followed by a decline as plants enterinto senescence. This trend is more notori­ous in the case of the larval population.

Eggs/female

Total life cycleFemale

Mole

Egg

larvaI

IIIII

Pupa

longevi1y

Female

Male

Stage

Host-Plant Range

Total immature stages

The leafminer fly is a polyphagous insect thatinfests a large number of crop and ornamen­tal plants. The long list includes potato,beans, peas, alfalfa, and most vegetables (to­mato, celery, lettuce, peppers, spinach, cu­curbits, and others) grown in Canete andother valleys of the Peruvian coast. This hasimplications when crop rotation is being con­sidered. In addition, leafminer flies infestmany weed species.

178 Program 4

(IP Progrom Report 1995-96 179

When the leaf is mature, most of the eggremains encrusted in the leaf tissue untilhatching. Then, the neonate larva immedi­ately starts tunneling the foliar pallisade tis­sue. Larval survival is close to 100%. But soonafter the egg is laid, on a still-growing leaf, a

7 14 21 28 6 12Sept Oct

In contrast, when the plant is fully grown,from the flowering phase onward, foliar in­festation develops at a much faster rate allover the plant, giving the impression of a sud­den outbreak. The occurrence of egg extru­sion might explain this phenomenon.

Although potato plants can be infested byleafminer flies once they emerge from the soilsurface, larval damage is consistently lesssevere during the vegetative phase of theplant. At this time, the first leaves to showlarval damage are those of the lower part ofthe plant.

a100

a

Figure 1. Occurrence of mining (Ill) in potato foliage caused by leafminer fly larvae, in the bottom, medium,and top parts of the potato plant (cv. Revolucion), (anete, Peru, 1995.

3 10 17 24 31Aug

a100

It is common to see adult flies in potato fieldsfrom when potato plants emerge until theybecome senescent. Feeding punctures canoften be seen allover a growing plant, givingthe impression that a generalized outbreakof larval infestation is in process. But the de­velopment of the larval damage follows arather fixed pattern, somewhat different fromthat of the adult fly population. First, the ini­tial larval infestation and the correspondingdamage occur in the lower third of the plant.As infestation increases, the medium part ofthe plant is affected and, finally, the top ofthe plant becomes infested (Figure 1). At thistime, practically the whole aboveground partof the plant becomes necrotic and dies. Therate and level of infestation of plants are af­fected by varietal differences, age, and thephysiological state of the plant.

Insect-Potato Plant Interactions

Damage (%)

100

40

adult flies and larvae, usually with mediocreresults. The alternative methods investigatedincluded the evaluation of susceptibility/tol­erance of commercial cultivars, the develop­ment of tolerant potato clones, the role ofnatural enemies, effects of cultural practices,trapping devices, and the selective use of lar­vicides. These techniques, along with meth­ods for monitoring the fly population, are thebasis for structuring the integrated manage­ment of th is pest.

Differences in susceptibilityExperiments to test the degree of suscepti­

bility among the most common varieties cul­tivated in Cafiete showed differences in thearea of fol iage mined, the necrosing rate ofthe mines, and yield reduction. Effects of flyinfestations on yield reduction were deter­mined by comparing plots with and withoutcontrol measures (Figure 2).

Developing resistant/tolerant clonesBreeding work at CIP resulted in genotypes

with reasonable levels of tolerance of

Ciea Tomasa Revoluci6n Perrieholi YungayAmarilis Canehan

o

20

25

30

5

10

(tlha)

45 .

15

35

proliferation of cells occurs in the tissue sur­rounding the egg. That results in the extru­sion of the egg to the leaf surface. There, theegg remains exposed to the action of adversephysical factors (mainly dehydration) andpredators.

Developing Management Components

The neonate larvae that are able to hatchare also exposed to dehydration and preda­tion before starting to tunnel into the leaf tis­sue. More than 90% of the eggs were extrudedand around 60% of the eggs and neonate lar­vae died by dehydration under laboratoryconditions. Under these conditions, lowerlarval infestation during the vegetative growthof the potato plant would be expected, de­spite a high adult fly population. The prob­ability of successful larval development froman egg in mature foliage is much higher thanin a growing leaf.

Farmers' only measure to control leafminerflies is the heavy use of chemicals against

Figure 2. Yields of treated (0) and nontreated (_) plots to controlleafminer fly infestation in the mostcommon potato cultivars in (anete, Peru (average of two years: 1994-95).

180 Program 4

leafmi ner fly infestations, high yields, andgood quality characteristics. Farmers of theTambo valley participated in the final selec­tion of a group of these materials. Farmersselected clone CIP-282 after evaluating itsgrowing period, harvest, yield, cooking quali­ties, processing qualities, and marketability.Yields of marketable tubers were double thoseof the leading local variety Canchan at me­dium elevation in the Cafiete valley, 30.4 t/ha vs. 15.2 t/ha. At high elevation, CIP-282yielded 51.6 t/ha compared with 33.5 t/ha forCanchan. The clone has been released asMaria Tambefia by the Instituto Nacional deInvestigaci6n Agraria (INIAl. The good quali­ties of this new variety are in great demandby farmers.

Biological control: occurrence and roleof natural enemiesAn important complex of natural enemies

attacks leafminer fly larvae in the Cafiete val­ley. Intensive sampling of infested leaves ofpotato and bean plants rendered 10 speciesof parasitoids whose seasonal occurrence andrelative effectiveness against leafminer flyhave been determined. Endoparasitoids andectoparasitoids were recorded. The occur­rence of high parasitism (close to 100%) dur­ing the warmer months of the year seems tobe the factor responsible for the extremely lowpopulations of the fly during this period.

Ectoparasitoids recorded are Oiglyphuswebsteri (Craw.), O. begini (Ash.), Oiglyphussp., Closterocerus cinctipennis Ash., andZagrammosoma multilineatum (Ash.). Thefemale ectoparasitoid first paralyzes the flylarva in the leaf mine and then lays its eggs inthe vicinity of the larva. The parasitoid larvafeeds externally on the fly larval body andpupates inside the leaf. In the case of theendoparasitoids, the female lays an egg in­side the body of the fly larva where the larvaof the parasitoid develops.

Pupation of the parasitoid occurs inside thefly puparium, which is formed outside the leaftunnel. Endoparasitoids recorded areHalticoptera sp., H. arduine (Walker),Chrysocharis sp., C. phytomizae (Bre.), andGanaspidium sp.

Ectoparasitoids were abundant in beanplants. O. websteri showed the highest per­centages of parasitism followed by C.cinctipennis. Endoparasitoids were moreabundant in potato plants. H. arduine was themost common parasitoid in potato followedby O. websteri. The value of weeds as sourcesof parasitoids cannot be disregarded as wehave recovered from weeds a rich fauna ofparasites that attack leafminer flies. Averageparasitism in 18 weed species was 44%, witha maximum of 71 %. Not all parasitoids havebeen identified.

Predatory flies of the familiesDolichopodidae and Empididae were foundcapturing and killing leafminerfly adults. Al­though these voracious predators have beenobserved occasionally in large numbers, theirimportance has been difficult to assess quan­titatively due to the lack of adequate sampl ingmethods.

Cultural practicesHealthy, vigorous-growing potato plants

are able to counteract the effect of leafminerinfestation, particularly during the vegetativephase. The fast-growing foliage enhances theegg extrusion reaction of the fol iar tissue.Plants deficient in irrigation water and fertil­izer, or coming from low-quality seed (e.g.,virus-infested seed), show damage earlier andtheir tunneled leaves dry more rapidly. Un­der these circumstances, low yields due toinadequate agronomic conditions or low­quality seed are further reduced by the syn­ergistic effects of leafminer fly infestations.

Trapping devicesThe attractive effect of yellow surfaces on

leafminer flies was reported in the early19805. Yellow surfaces covered with a stickysubstance were used for trapping adult fliesto monitor their populations. Years later CIPentomologists verified the trapping effects ofyellow sticky traps and expanded their usefor mass trapping leafminer flies in controlprograms. By using 60 fixed traps/ha, the num­ber of insecticide treatments was reduced from4-6 sprays to 1-2 sprays in the Tambo valley,Peru, where fly infestations are moderate.

ClP Progrom Report 1995-96 181

182 Program 4

ment was the use of mobile traps-yellowplastic sheets that are passed over the plantcanopy covering four or more rows at a time.Farmers adopted them readily and modifiedthem according to their ingenuity. Figure 3shows the effect of trapping on the fly popu­lation compared with a check field. Trappingcan replace the use of insecticides againstadult flies.

Experiments were also conducted to im­prove trapping efficiency. Aspects studiedwere the effective attractive distance of thetraps, the number of traps required per hect­are, orientation of the traps in relation to wi nddirection, spatial distribution of the traps,optimum timing for the installation of trapswith respect to crop growth, trapping effi­ciency and in relation to the field fly popula-

1.71.1

23 31 7 14 21 28 5 12 19 26 2 9 16Aug Sept Oct Nov

29 37 44 51 58 65 72 79 86 93 100 107 114

25

July

o

5

Days afterplanting

10

20

Leafminer fly infestations in the Caiiete val­ley are much more severe than those of theTambo valley. Yellow traps became saturatedand needed to be changed before the end ofthe cropping season despite the use of 80-1 00traps/ha. Close to 5 million flies/ha/season werecaptured in evaluated plots. Half that amountwas enough to saturate 100 traps. The increasein the number of traps required and the need tochange them in the middle of the season madetheir use too expensive. The original traps weremanufactured with expensive, importedsticky materials (cost of the yellow plastic plusthe sticky material was about $1 per trap) thatmade them uneconomical under severe sus­tained fly infestations. Therefore, new, cheap,locally available materials were tested. Themost cost-effective alternative was automo­tive motor oil 50SAE, which reduced the costfrom $234/ha to $66/ha. A further develop-

15

30

40 38 3 -"'- With t pin.... ··M·~bii~·;;~·~~·· ··,f·,,·,f ··r·..·· ····..· ····· -+- conlr~~P g.

35 .

Adult flies/plant

50 .

45 :.~~~~.~~~p.~ , ...................•.....................'1. .

25

Figure 3. Effect of tropping on leofminer fly field populotion, comporison of fields with and without trapping,Cafiete, Peru, 1996.

tion, and comparisons of efficiency of fixedtraps vs. mobile traps.

Selective use of larvicidesA critical aspect of leafminer fly manage­

ment is the reduction in the use of insecti­cides. Farmers tend to spray wide-spectruminsecticides as soon as they see the first adultflies on the foliage. Nothing is more inappro­priate than this. Flies are not only tolerant ofmany compounds, but readily develop resis­tance to them. Even if affected by a spray, thetreated population recovers rapidly becauseof immigration. Worse, early sprays againstadults destroy natural enemies of leafminerflies and other pests early in the season. As aresult, resurgence of the fly occurs and newpests are encouraged, as in the cases of thewhite mite and budmidge in Cafiete.

The combined effects of egg extrusion bythe growing foliage, which can be furtherstimulated with good cultural managementpractices, and the yellow sticky traps can ef­fectively counteract the apparent need to useinsecticides against adult flies.

Nevertheless, potato plants, after vegeta­tive growth stops, might need protection fortheir foliage against the mining larvae if thelevel of control by natural enemies is notenough to avoid yield reductions. When thesesprays are required, they should be as selec­tive as possible. Cyromazine is effectiveagainst fly larvae and is largely compatiblewith natural enemies.

Monitoring Methods for Fly Damage andPopulation levels

Monitoring pest populations and damage hastwo purposes: to study the population dynam­ics of the pest and to make decisions aboutcontrol measures.

Monitoring adult fly populations by count­ing the number of flies per plant or the num­ber of flies captured by sticky traps is usefulfor population dynamics studies. Both meth­ods have been used in our studies and wehave found a fairly good correlation betweenthem.

For many years, monitoring fly infestationfor deciding spray treatments was based onadult fly counts. But we have demonstratedthe inconsistent relation between adult andlarval populations. In most cases, adult countslead to unnecessary sprays. The alternativeis to count the number of larvae or fresh tun­nels per leaflet by sampling the bottom,middle, and top parts of the plant. This hasproved to be an efficient method for decid­ing when to use larvicide sprays.

Unfortunately, direct observation of larvaein the field does not provide informationabout the incidence of natural enemies. Toget this information, infested leaflets must betaken to the laboratory and kept for 21 days.By that time we know the number of adultflies that developed from healthy larvae, thenumber of larvae killed by insecticides, andthe level of parasitism based on the numberof parasitoids recovered (Figure 4). But a 21­day delay in obtaining this information is toolong for deciding the timing of a spray. In sev­eral of our experiments, we found that a sec­ond larvicide spray could be avoided if wehad the information on parasitism at the timeof sampling. More research is needed to solvethis problem.

Conclusions

The amount of research conducted so far onthe development of IPM components forleafminer flies allows us to offer a prelimi­nary menu of options to farmers. Some pre­liminary trials envisage the possibility of re­ducing the number of sprays currently used(8-13) against leafminer flies to one or twosprays per season. The integration and imple­mentation of IPM programs in farmers' fieldswill be completed with economic evaluationsof the practices adopted.

(IP Program Report 1995-96 183

18 25 1 8 15 22 29 6 13 20 11 17 23 31 7 14 21 28 5 12 19 26 2 9 16

NovOct

Imll ".. ~ .. "~.~ .. "..... u ••••••••

Sept

II'························

o Dead larvae

• Parasitoids.. rill Adult flies

o Closed puparia

Winter planting

AugJulJunMay

2 ..

5 .

4 .

3 .

2 .

1 .

a

2.5

1.5 J~~!~.~~P!~~·~~~·..· ~!,!,!.!mm! "'1'.". .

Larvaelleaflet

1 ~••~ .. ::. ~mmi 'iilil!'" ,iiiiiif jimll

0: ···············~11111~~!I{:~::!I""']rI·I····· ..{l~I!~mlll ~

A 3 ..

Larvae/leafleto 6 .

Figure 4. Monitoring of leafminer fly population. Comparison between (AI direct sampling observation in thefield and (Bl field sampling and laboratory analysis, 21 days after sampling. Note that in thelaboratory analysis healthy larvae and larvae affected by parasitoids and insecticides can be detected.(l = cyromazine treatment, a = sampled 1day after treatment.)

184 Progrom 4

Large-Scale Implementation ofIPM for Sweetpotato Weevil in Cuba:A Collaborative Effort

J. Alcazar!, F. Cisneros!, and A. Morales2

ClP started investigating the sweetpotato wee­vil, Cylas formicarius (Fabricius), the mostinjurious pest of sweetpotato in the Caribbeanarea, in 1990. Activities were concentratedin the Dominican Republic on the use of sexpheromone traps. In 1993, studies were ex­panded with financial support from the Or­ganization of Petroleum Exporting CountriesFund for International Development, andCuba was included. Cuban scientists partici­pating in an IPM workshop in Santo Domingo,Dominican Republic, expressed their inter­est in collaborating with CIP in managing thispest in their country, where 60,000 ha areplanted to sweetpotato each year.

Scope of the Problem

The Asian sweetpotato weevi I is the mostimportant sweetpotato pest in the Caribbean,and practically the only one in Cuba. Dam­age is so severe that when insecticides fromthe Soviet Union were no longer available inCuba (1991-92), damage amounted to 40­50% of production. Previously, Cuban farm­ers had sprayed their sweetpotato fields 10­12 times per season, with damage amount­ing to around 10% of production.

The pest is present in all provinces of thecountry. Historically, reported yields oftradi­tional cultivars were low (6 t/ha), but in areaswhere new varieties developed by theInstituto Nacional de Investigaci6n deViandas Tropicales (INIVIT) were planted,yields reached 20-30 t/ha.

It is difficult to express yield losses in eco­nomic terms, because of the special charac-

1 CIP, Lima, Peru.2 Head, IPM team, INIVIT, Cuba.

teristics of the Cuban economy. But if no con­trol measures are taken, weevil damage tosweetpotato is equivalent to a total loss of24,000-30,000 ha annually, about half thearea planted to the crop.

Sweetpotato is one of the staple foods inCuba. The other crops include banana, cas­sava, yam, and cocoyam.

Rationale of IPM Componentsand Their Integration

The urgency created by the sudden lack ofinsecticides and the resultant rapid increasein weevil damage obviated the need for as­sessment and characterization of the pest,which normally constitutes the first phase ofCIP's strategy. The need to produce enoughfood with limited resources during what Cu­bans call the "special period" of the Cubaneconomy made sweetpotato production evenmore important. First, efforts concentrated ondeveloping IPM components and filling someknowledge gaps in the biology and seasonaloccurrence of the weevil.

Maximum efforts were initially dedicatedto compiling and verifying information aboutresearch and experiences for controlling theweevil worldwide. Later, knowledge gapswere identified during coordination meetingswhen new results were discussed and newresearch activities were scheduled.

A significant amount of new informationwas generated through research conductedwithin Cuba. The only new key componentforeign to the Cuban experiences was the useof pheromone traps, which CIP had been test-

(IP Program Report 1995-96 185

~I Migration I

Colonization

New sweetpotatofield

Crop rotationAbout 20% of the area planted with

sweetpotato is rotated with potato. Insecti­cides and the relatively large amount of wa­ter used in potato fields destroy all remainsof the weevil population in one season. Withno crop rotation, the number of weevi Is cap­tured by pheromone traps in a 60-d periodexceeded 8,000.

7. Irrigation management (avoid soil cracking)8. Early harvest9. Crop rotation

10. Destroy crop residues11 . Destroy volunteer plants12. Avoid neighboring, old sweetpotato fields

cooperatives. A l-ha plot produces enoughhealthy cuttings to plant 20 ha in 4 mo.

That was reduced to 418 weevi Is after a1-yr rotation with crops other than potato, 40weevils after 17 mo, and only 2 weevils after2 yr. Rotation is even more effective as moresuccessive crops are planted within the samerotation period.

Neighboring fieldsIn highly infested areas, INIVIT recom­

mended separating new sweetpotato plantingsfrom older fields by at least 1,000 m. Infesta-

1110

Harvestresidues

andvolunteer

plants

Multiplication I

® =Control measure

\1

Sweetpotatofield

1. Early tolerant or resistant cultivars2. Healthy or disinfested cuttings

(chemically or Beauveria bassiana-1reated)3. Sex pheromone4. Beauveria bassiana5. Colonization or predatory ants6. High hiiling

ing and improving in the Dominican Repub­lic for several years.

Research led to the identification of a se­ries of practices to reduce the weevil popula­tion or its damage, and a basic IPM programwas designed (Figure 1). These practices wereoffered to farmers and agrarian-cooperativetechnicians as menu options. The initial dem­onstration fields were located near INIVIT'sstation in Santa Clara. The main practices rec­ommended were biological and cultural.

Cultural Control Components

INIVIT established a system to producelarge quantities of healthy seed cuttings in

Healthy planting materialPlanting infested sweetpotato stem cuttings

is a primary way to distribute sweetpotatoweevil. More than 95% of the eggs are de­posited in the first 35 cm of stem. By discard­ing the basal stem portion, the apical portionof the stem makes a healthy cutting.

Figure 1. Sweetpotato weevil: population dynamics and management in Cuba.

186 Program 4

9.9 c

CIP Program Report 1995-96 187

25.8 ab

Biological Control Components

DisinfestationUnder heavy weevil infestations, healthy

cuttings (without eggs and larvae) may stillharbor adu Its that are attracted by the cutstem. Cubans disinfest cuttings by dippingthem in a dilution of the parasitic fungus

Varietal selectionEarly maturity and deep storage roots help

sweetpotato escape weevil damage. Shallow­rooting varieties are four times more infestedthan varieties that root 8 cm below the soilsurface. Early-maturing varieties (90-120 d)are three or four times less infested than latevarieties (180 d or more). The recommendedvarieties in Cuba are INIVIT B-88, CEMSA 85­48, Cautillo, and CEMSA 78-354.

Cracking of the soil because of drought ordeficient irrigation waterfaciI itates female wee­vils reaching the sweetpotato fleshy roots todeposit their eggs. Well-irrigated fields are cOm­monly 4-5 times less infested than those suffer­ing from moisture deficit (Table 1).

31.5 abc

0.6 de2.7c4.4 b

Table 1. Effects of some selected IPM components for sweetpotato weevil in Cuba expressed as damage (%infested storage roots) and yields in spring-planted experimental fields, INIVIT, Villa Clara, Cuba, 1994.

Destroying crop residuesField sampling from various parts of Cuba

showed that crop residues left on fields aver­age 0.7 t/ha. That is enough material to har­bor as many as one million weevils. Elimi­nating harvest residues increases the effec­tiveness of the other IPM measures.

Water managementIn Cuba, 70% of the sweetpotato crop

(42,000 hal is planted in the rainy season andthe rest during the dry season. Soil moistureis essential for plant growth and it has a cleareffect on weevil infestation levels.

Timely harvestFarmers may delay harvest after physi­

ological maturity to increase yields or to gethigher prices at a later date. But in Cuba,postponing harvest 30 days means a fourfoldincrease in damage. INIVIT recommendedharvesting mature crops before the level ofinfestation reached 3%.

tion risk increases with proximity to oldersweetpotato fields.

188 Program 4

1996

128,000

1995

Year

Successful implementation of IPM requirescollaborative commitments from institutionsdevoted to helping farmers in their crop pro­duction. In the Cuban case, an ideal situa­tion was presented with the interest of INIVITin collaborating with ClP to develop a pro­gram for management of the sweetpotatoweevil. INIVIT is the Cuban research institu­tion in charge of tropical staple food crops inthat country.

The Collaborative Approach:The Role of INIVIT

With 16 traps/ha, the weevil population issignificantly reduced. Captured weevils arekilled by insecticides or by spraying the para­sitic fungus Beauveria bassiana.

INIVIT's activities to improve sweetpotatoproduction include developing new, moreproductive, short-season varieties, improvingagronomic and plant protection practices, andtraining farmers on management of thesweetpotato crop during the rainy and dryseasons.

19941993

o

40,000

20,000

120,000

Number of traps

100,000

80,000

60,000

140,000

Beauveria bassiana, which kills infected wee­vils within 2 or 3 d after treatment.

Fields planted with disinfested cuttingsshowed 3-4 times lower weevil populationsthan those with nondisinfested cuttings.

PredatorsTwo species of predatory ants, Pheidole

megacephala and Tetramorium guineense,are common inhabitants of banana planta­tions. INIVIT has devised a simple systemusing rolled banana leaves as artificial inter­mediary nests to transport the ants from theirnatural reservoir to the sweetpotato fieldswhere they prey upon weevils and other in­sects. Colonizing fields 30 d after plantingwith 60-110 nests/ha can keep weevil infes­tation at low levels (3-5%).

Figure 2. Number of sex pheromone traps used in Cuba to manage the sweetpotato weevil, (ylasformicarius, INIVIT-Clp, 1996.

Pheromone trappingMass trapping of male weevils using sex

pheromone traps efficiently controls thesweetpotato weevil. Farmers consider phero­mone traps as an essential IPM component(Figure 2).

The strategy for implementing IPM for thesweetpotato weevil in Cuba was based on CIP'sexperience in managing potato pests such asthe Andean potato weevil Premnatrypes spp.and the potato tuber moths Phtharimaeaapercu/ella and Symmetrischema tanga/ias inthe Andean region. Some INIVIT researchersvisited ClP's headquarters to become aware ofCIP's work on IPM. Other INIVIT staff partici­pated in training courses organized by ClP inthe Dominican Republic and Cuba.

INIVITtookthe responsibility for all the workon research and implementation in Cuba. ClP'sstaff participated during the planning phases ofthe research and reviews of the program, andsupported the diffusion activities.

One or two visits to Cuba a year to jointlyanalyze progress and suggest adjustments tothe program completed the collaboration.After 3 years, Cuba's experience was used asthe background for a 1995 workshop on man­agement of the sweetpotato weevi I, with theparticipation of specialists from Cuba and theDominican Republic.

The Pilot Units

The first pilot unit, where most of the IPMcomponents were integrated, was establishedin Arimao, Cienfuegos Province, with govern­mental enterprises, cooperatives, and privatefarmers with small landholdings. The pilotarea increased from 250 ha in 1993 to 908ha in 1995.

A second pilot unit was established inSanta Clara, Villa Clara Province, with 120ha in 1993 and 620 ha in 1995. Other pilotunits were in La Habana and Santiago deCuba, with a total of 400 ha in 1993 and 781ha in 1995.

Training

Training received a high priority for develop­ing the large-scale phase of sweetpotato IPMin Cuba.

In 1995, INIVIT trained 4,965 people through4 courses, 78 talks, 23 field days, and numer-

ous field and monitoring visits. Follow-uptraining was conducted in 1996 and anIPM International Workshop was held withparticipants from the Dominican Republic,Peru, Venezuela, and all the provinces ofCuba.

Large-Scale Implementation

The Cuban experience of successfully man­aging sweetpotato weevil in a fairly large area(10,000 ha in 1996) created a demand forlarge-scale implementation in the rest of thecountry. Figure 3 presents the distribution ofthe implemented areas.

As a result of the IPM program, weevil dam­age decreased from an initial level of 40-50%to 4-8%, after 3 yr. The number of insecticidesprays was reduced from 10-12 per season in1991-92 to zero in 1996, the only exceptionbeing limited sprays surrounding pheromonetraps (16 traps/hal. The area sprayed is around480 m2 compared with 10,000 m2 convention­ally sprayed over an entire hectare. The fungusB. bassiana has since replaced the use of insec­ticides. Finally, yields have increased from thereported 6 t/ha to 15-30 t/ha.

The INIVIT IPM team, our counterpart, re­ceived the Cuban Government 1996 RelevantAward for the Cuban IPM project.

All the components of the IPM programare available locally except for the sex phero­mones. That limitation is the only foreseeableconstraint to reaching national coverage of60,000 ha in the near term.

Selected Reading

Cisneros, F., J. Alcazar, M. Palacios, andO. Ortiz. 1995. A strategy for developingand implementing integrated pestmanagement. ClP Circular 21 (3):2-7.

Cisneros, F. and P. Gregory. 1994. Potatopest management. Aspects Appl. BioI.39: 113-124.

(IP Progrom Report 1995·96 189

1,562

1,340

\,'\ Clara .S .' ,,~~I .J8a'ncll ') Cieg? -:' ':'SJv SpiritusL~e Av~~r"

684

Figure 3. Management of the sweetpotato weevil in Cuba: area (ha) under IPM implementation in 1996,INIVIT-CIP.

190 Progrom4

Integrated Pest Managementfor Sweetpotato in East Africa

N. Smitl and B. Odongo2

In East Africa, sweetpotato is mostly grownas a subsistence crop by resource-poor femalefarmers, who do not use inputs. Often, a fewroots are dug up and sold to generate cashfor household necessities. Production plotsare small, rarely larger than 0.5 ha, althoughsome larger-scale production exists. The cropis grown in two types of food systems. One iscereal-based, where sweetpotato is a food­security crop, as in Kenya. The other isnongrain, starchy staple-based. In this system,sweetpotato is one of several staple foods, andplays an important role in Uganda, Rwanda,Burundi, and adjacent parts of Zaire and Tan­zania. Uganda alone produces 2.0 million tannually, making it the world's fourth-largestsweetpotato producer.

Agroecological conditions under whichsweetpotato is grown range from semiarid tohigh-altitude, temperate climates. There isalmost no fresh storage of roots. Farmers prac­tice in-ground storage and piecemeal harvest­ing. This means that crops are left in theground for 7 mo to more than a year, androots are removed as necessary for fami Iymeals. Th is practice guarantees that freshroots are available for consumption during alarge part of the year. But it also means thatsweetpotato crops are in the field throughoutthe year in many areas where they are sus­ceptible to pest infestation.

Since 1990, ClP researchers have collabo­rated with the national root crops programsof Kenya, Uganda, and Tanzania; the CropScience Department of Makerere University;the Natural Resources Institute (NRI), UnitedKingdom; and the International Institute of

1 ClP-Uganda.2 National Agricultural Research Organization (NAROl,

Uganda.

Biological Control (IIBC) to develop integratedpest management (iPM) for sweetpotato inEast Africa. The major pest in the region isthe sweetpotato weevil Cy/as spp.

IPM development can be divided into fivedistinct and consecutive phases, some ofwhich may overlap. They are (1) pest prob­lem assessment and characterization, (2) de­velopment of management components, (3)integration of key components, (4) implemen­tation of IPM in pilot units, and (5) implemen­tation of IPM on a large scale.

This CIP strategy has proven to be verysuccessful in managing potato pests in theAndean region and North Africa, and man­aging sweetpotato weevil Cy/as formicarius(Fabricius) in the Caribbean. However, thesesuccesses were obtained with commercialcrops grown by relatively resource-rich farm­ers who commonly use insecticides to pro­tect their crops. The situation of sweetpotatoproduction in East Africa is very different andrequires adjustments in strategy and expec­tations.

Pest Problem Assessment

Socioeconomic research into sweetpotatoproduction and use pointed toward someimportant considerations relating to pest con­trol.

First is farmers' perceptions of pest prob­lems. It makes little sense to help farmers solveproblems that they do not consider important.During surveys throughout East Africa, farm­ers in areas with long dry seasons indicatedthat root-damaging sweetpotato weevils(Cy/as spp.) were a major constraint to theirsweetpotato production. An insect pest of

C1P Progrom Report 1995-96 191

192 Progrom 4

Number of eggs

per female per

day

Host-plant resistanceSo far, research has not identified

germplasm immune to C. formicarius. Butsome studies suggest that sweetpotato clonesdiffer in their levels of resistance. These lev­els are low and do not stand up under highweevil pressure. ClP and its collaboratorshave conducted several field and laboratoryexperiments with varieties from localgermplasm collections to detect resistance tothe African sweetpotato weevil species.

The technological options for an IPM programinclude host-plant resistance; biological con­trol; cultural control; chemical control; andbehavior-influencing techniques such aspheromones, sticky traps, and repellents.Methods described in the Iiterature for con­trolling C. formicarius were validated underambient conditions for the local species. Prac­tices that farmers traditionally use to controlpests were considered as a good basis for re­search and verification trials.

Development of ManagementComponents

ing planting and harvesting times so that rootsare not present in the dry season.

Although some varieties were clearly lesssusceptible than others, no reliable source ofresistance has been identified. Conventionalbreeding techniques appear to have limitedpotential to incorporate weevil resistance intosweetpotato. An alternative approach understudy is the development of transgenic sweet­potato with proteinase inhibitors for Cylas spp.

regional importance is the sweetpotato but­terfly Acraea acerata in the high-altitude re­gions of Uganda, Rwanda, and Burundi.Throughout these regions, most sweetpotatoroots are destined for home consumption.Consequently, quality demand is low andwhat entomologists consider high pest levelsare tolerated.

Biological research is one part of pest prob­lem assessment. The sweetpotato weevi I spe­cies found in East Africa, Cylas puncticollis(Boheman) and C. brunneus (Fabricius), areunique to the continent. Their counterpart C.formicarius (Fabricius) is a pest onsweetpotato in Asia, the United States, andthe Caribbean. It has been widely studied, butlittle or no published information is availableon the biology and ecology of the Africansweetpotato weevil species or on thesweetpotato butterfly. Basic studies revealeddifferences in the biology of the two weevilspecies (Table 1) and the presence of species­specific pheromones for the weevils.

Knowledge of sweetpotato weevil ecology,biology, and behavior may indicate how tomanage the pest. For instance, weevils can­not dig down through soil; the only roots fe­males can lay their eggs in are those they lo­cate through soil cracks or those exposedaboveground. Soil cracks are more commonduring the dry season, thus exposing roots forattack. Possibilities for control are the use ofvarieties that escape weevil damage by pro­ducing roots deep in the soil, covering ex­posed roots with soil and filling soil cracks toprotect roots from weevi I attack, and adjust-

Table 1. Life cycle data on two Cylasspecies taken in Kenya at 27±lO( and 45±5% relative humidity, 1992.

Some varieties are less susceptible to wee­vil damage than others due to an escapemechanism known as pseudoresistance.Short-season varieties can be harvested earlybefore the weevil population builds up. Deep­rooted varieties escape weevil damage be­cause their roots are less accessible for fe­males to lay eggs.

Biological controlBecause several Iife stages of sweetpotato

weevils are completed underground withinthe roots, it is difficult for parasites to locatethem. Entomopathogenic fungi, bacteria,nematodes, and ground-dwelling insectpredators appear to have greater potential asbiological control agents of Cylas spp.

Of all known fungal pathogens reportedto attack Cylas spp., Beauveria bassiana is thepredominant species. In East Africa, scientistsfrom IIBC isolated several strains from field­infested C. puncticollis and C. brunneusspecimens. ClP collaborated in experimentsto field-test strains that had proved to be themost pathogenic in the laboratory. Resultswere inconclusive.

Further field experimentation is plannedin swampy areas, where farmers maintaintheir sweetpotato planting material during thedry season. Here environmental conditionsmight be more suitable for establishment ofthe fungus.

Cultural controlRecommended cultural practices that may

help reduce C. formicarius damage includecrop rotation, field sanitation, use of cleanplanting material, planting away from wee­vil-infested fields, hilling up to reduce soilcracking, adjusting planting time, and timelyharvesting.

The ecology and biology of C. puncticollisand C. brunneus are similar to those of C.formicarius considering flight activity, hostrange, and mode of entry into the plant. Inprinciple, the cultural practices advocated forreducing damage by C. formicarius also applyto the African sweetpotato weevil species.

Collaborative field experiments at researchstations in Uganda and Kenya on some of thecultural practices confirmed this. However,the production systems of sweetpotato in Af­rica are very different from those ofthe UnitedStates and Asia, where the recommendationswere developed. Suitable cultural controlpractices are site-specific and depend onagroecological and socioeconomic condi­tions. Some practices such as hilling up androtation have become so common amongfarmers for agronomic reasons that they arenot recognized as control techniques.

Two practices that are expected to havethe most noticeable effect on weevi I control­good field sanitation and planting away fromweevil-infested fields-might require a com­munity effort in densely populated areas.Practices that would require more labor fromfarm families might be a constraint, especiallyduring peak periods of farm activity. An ex­ample is extra hilling of mounds and fillingsoi I cracks.

The traditional practice of in-ground stor­age combined with piecemeal harvesting iscontrary to the recommendation of promptharvesti ng. On-station research, however,demonstrated that accumulated yield andyield loss under piecemeal harvesting com­pared favorably with once-over harvesting atthe optimum harvesting time (Figure 1).

Knowledge of the biology and behavior ofweevils will give farmers insight into the ra­tionale behind recommended cultural prac­tices. Site-specific, farmer-participatory re­search on cultural practices is presentlyneeded, to verify which practices fit the farm­ers' uses and customs.

Sex pheromonesThe sex pheromone of C. formicarius, iden­

tified in 1985, proved to be an important com­ponent of an IPM program for this insect inits host range. C. puncticollis and C. brunneusappear to have their own species-specific, fe­male-produced pheromones. In 1995, a hold­back project funded by the Overseas Devel­opment Administration (aDA) began devel-

CIP Program Repor11995-96 193

Figure 1. Comparison of yield and yield loss due to sweetpotato weevil damage between once-over harvestedplots and a piecemeal harvested plot, Namulonge, Uganda, 1995.

Piecemeal9.58.57.5

Chemical controlMost sweetpotato weevil life stages take

place underground within plants. Therefore,postplant application of insecticide requiresfrequent applications to kill newly emergedadults. This is not cost-effective for subsis­tence farmers. Preplanting insecticide appli­cations by dipping cuttings in systemic insec­ticide kill weevils within the vine and canprotect it for at least 1 mo after planting. Butthe chemicals involved are highly toxic, andexpensive. For these reasons, little attentionis paid to chemical control of weevils.

Farmer Participatory Researchin Pilot Area

The most promising IPM components at themoment-cultural control practices and sexpheromones-both require adaptation byfarmers. The input of farmers at an early stagewould alert researchers to any major unfore­seen constraints to the eventual adoption ofthese management components. Research onother components, such as host-plant resis­tance and biological control, for whichreadily available technologies do not yet ex­ist, can continue at the research stations.

6.55.54.53.5

Harvesting time (mo after planting) or method

Yield (tlha)20

18 1m Infested yield

16 mClean yield

14

12

10

8

6

4

2

o

oping pheromones for monitoring and con­trolling the African Cylas spp. This is a col­laborative project of the National Agricul­tural Research Organization (NARO) ofUganda, NRI, and CIP. NRI identified phero­mone compounds that proved effective incatching male weevils under field condi­tions in Uganda. Exciting research resultshave been obtained on the most effectivetrap type (Figure 2), pheromone dose, lureand composition, male weevil diurnal ac­tivity (Figure 3), etc. A 5-L jerry can, filledwith soapy water and tied to a pole so thatit hangs slightly higher than the canopy ofthe crop, is presently the most effective androbust trapping system.

We are conducting on-station field experi­ments on the use of pheromone traps for masstrapping of males for weevil control. Withparticipating farmers, mass trapping experi­ments have begun in small planting materialnurseries, which are kept during the dry sea­son. During this time of the year, thesweetpotato area is smaller and mass trap­ping might be more feasible. Sex pheromonetraps might show potential as a componentof IPM.

194 Progrom 4

D

G

~i ... ~

~q~/)

(IP Progrom Report 1995-96 195

7-11 am 11-3 pm 3-5 pm 5-7 pm 7-9 pm 9-12 pm 12-4 am 4-7 am

Time

Percentage of total catches

100 ,..---------------------------

90 -j--;::======;-----------­80 -1--+=....::;.;...<;;;=.;;;;.:;.==--1------------

70 +--b===;,;;.,;..,;,,;,==~----------­

60 -1----------------j

50 -1----------------j

40 -1-----------------1

30 -1-----------------1

20 -I-------------l

10 -1-------------l

O-l----'=--,--.L.-..........-..L-...L..,r----'--'-,..----'----L-,-...-.L.---r-

Figure 3. Diurnal timing of male weevil catches in their respective sex pheromone traps, Namulonge,Uga nda, 1996.

Figure 2. Seven pheromone trap types tested in Uganda: (A) plastic funnel trap, (8) l-l bottle/funneltrap, (e) 2-l plastic jerry can trap, (D) S-l plastic jerry can trap, (E) 4-l metal oil can trap, (F)Uni-trap, (6) sticky disc trap.

IPM in complex, diverse, and risk-proneagriculture in sub-Saharan Africa has had fewsuccesses. Those reported were based onclassical biological control or highly resistantvarieties, or involved cash crops on whichthere was an overuse of insecticide. None ofthese conditions relate to IPM for sweetpotato,so a careful approach has to be taken. To in­crease the Iikel ihood of practical success ofthe program, some modification of the CIPIPM model is required.

Selection of pilot areaPests are often but one of many risks and

sweetpotato but one of many crops. Farmersin East Africa often tolerate high yield losses.It is important to select a pilot area where pestmanagement of sweetpotato might be a highpriority for farmers.

A combination of specific socioeconomicand agroecological factors controls the selec­tion of an IPM pilot site in East Africa. At thesite, sweetpotato should be a basic staple foodor a major cash crop, rainfall should be lowor poorly spread seasonally with one or twolong dry seasons, and sweetpotato produc­tion should have become increasingly impor­tant and intensive.

Part of northeastern Uganda forms a re­gion within East Africa that fulfills all threeconditions and is suitable as a pilot area forsweetpotato IPM. A suitable pilot area wasfound in Gweri subcounty in Soroti District.

Sweetpotato is the predominant staplecrop, providing the majority of dietary starchthroughout the year. And it is an importantcash crop for the Kampala market during themajor harvest months. Urban consumers pre­fer one variety, Tanzania, which is early ma­turing and highly susceptible to weevil attackdue to its rooting characteristics. Farmers alsoIike this variety for its taste and high yield.

The preferred staple and important cashcrop cassava had virtually disappeared fromthe area due to African cassava mosaic virusdisease (ACMVD) since 1986, but is slowlyreappearing in the form of resistant varieties.

196 Program 4

Sweetpotato has taken over most of cassava'srole as a cash crop and for food security.

For similar reasons, the site was suitablefor testing storage technology of fresh roots,which offered the opportunity to extend theperiod of avai labi Iity of the crop. Before theonslaught of ACMVD, fresh cassava rootswere available more or less throughout theyear, as these can be stored in-ground on theplants. Sweetpotato plots, however, have tobe dug up at the beginning or toward themiddle of the dry season, becausesweetpotato weevil damage increases rapidlyto unacceptable levels.

At that time of the year, sweetpotato isdried and stored, to provide food during thelong dry season. However, the product can­not be stored very long because of commonstorage pests. Sweetpotato therefore cannotcompletely replace cassava, and a period ofinsufficient food availability occurs nearlyevery year just before the earliest harvest ofcereal crops in the rainy season. If final har­vesting of sweetpotato could be delayed 1mo, by reducing the incidence of sweetpotatoweevil, this would be a large benefit for thefarmers. IPM for sweetpotato weevils and stor­age of fresh roots are complementary in ex­tending the period of availability of the freshproduce.

Integrated crop management oeM)approach in pilot areaThe pilot program began in July 1996. En­

thusiastic extension staff and an NARO/CIP­sponsored local staff oversee the dai Iy activi­ties in the program. Basic information on im­pact of sweetpotato pests, farmers' knowledgeof pests, and current crop and pest manage­ment practices is obtained through participa­tory rural appraisal (PRA) methods, formalquestionnaires, and year-long recordkeepingin farmers' fields.

The research phase began in December1996. During the PRA exercises, farmers ex­pressed an interest in and need for manage­ment of sweetpotato weevils. In three targetvillages, farmer-experimenters, selected from

and appointed by the farmers involved in thepest problem assessment, are trained on thebiology and behavior of the insect pests, theecological basis for pest outbreaks, and therationale for the control measures to be tested.Mass trapping with pheromone traps, in com­bination with good field sanitation and plant­ing away from infested fields, is being testedin the dry-season planting material nurseriesin swampy areas.

Besides IPM components, farmers alsoexpressed an interest in testing other tech­nologies. In partnership with researchers fromother disciplines, testing of new varieties,methods for storing fresh sweetpotato, and theuse of sweetpotato in pig keeping takes place.Based on the needs and interests of the farm­ers, this integrated crop management ap­proach was taken, as it became clear thatyield loss due to sweetpotato weevil damagewas but one of several related constraints thatfarmers face in sweetpotato production.

The pilot project will run for two years. Iffarmers are convinced of the practical valueof an ICM program and take up crop protec­tion practices, more pilot units will be con-

sidered, including extension of the programto neighboring countries. We cannot expectquick results from the development of an ICMprogram for the subsistence crop sweetpotato,but the present holistic approach with farmerparticipation holds promise to improve theirliving conditions.

Selected Reading

Smit, N.E.j.M. n.d. The effect of the indig­enous practices of in-groundstorage and piecemeal harvesting ofsweetpotato on yield and quality lossescaused by sweetpotato weevil inUganda. Agric. Ecosyst. Environ.(I n press.)

Smit, N.E.j.M. 1995. Farmers' culturalpractices and their effects on pestcontrol in sweetpotato in South Nyanza,Kenya. Int. j. Pest Manage. 41 :2-7.

Smit, N.E.j.M., M.C.A. Downham,B. Odongo, D.R. Hall, and P.O.Laboke. n.d. Development of pheromonetraps for control and monitoring ofsweetpotato weevils, Cylaspuncticollis and C. brunneus, in Uganda.Entomol. Exp. Applic. (In press.)

CIP Progrom Report 1995-96 197

A.R. Braun\ E. Priatna\ R. Asmunati2, Wiyanto2,

Y. Widodo3, and E. van de Fliert4

Farmer Field Schoolsfor Sweetpotato in Indonesia

The first job for the project team was toanalyze sweetpotato cultivation as a farmingenterprise. The data gathering was managedby two farmers from each village who weretrained as field researchers. Each was respon­sible for supervising a network of five to eightfarmers in keeping a daily calendar of all ac­tivities, inputs, and costs related tosweetpotato production; for evaluating lossesfrom pests and diseases; and for recordingyield and income from the sale of the crop.

because he or she does not know how to esti­mate the yield, and usually accepts thetrader's offer with little, if any, bargaining.On harvest day, the trader returns with his la­borers to dig up the roots and transport themto market. If the output is higher than thetrader expected, the farmer receives no addi­tional benefit. If there is pest damage or theyield is lower than expected, traders often payfarmers less than the agreed-upon price.

Analyzing the sweetpotato enterpriseMitra Tani, a nongovernmental organiza­

tion (NCO); RILET; Duta Wacana ChristianUniversity (UKDW); eight farmers from fourvillages in East and Central java; and CIPjoined forces in 1994 to develop an FFS forsweetpotato. The four villages wereBendunganjati, Turi, Ngargoyoso, andKradenan.

Developing a Field School for Sweetpotato

The key resu Its from several seasons ofrecordkeeping are as follows:

• There is tremendous variability in inputuse and yields (Figure 1), even within asingle village.

But improving pest management was muchless important to them than solving market­ing problems. Farmers' main concerns are fluc­tuating prices and their weak bargaining posi­tion with the traders who buy the standingcrop in the field and monopolize the market­ing system. Under this system, farmers are notpaid according to what they produce. Sev­eral days or weeks before harvest, the tradermakes the farmer an offer for the output ofthe field. The farmer is at a disadvantage

Sweetpotato (Ipomoea batatas) is a com­mon rotation crop in java's irrigated rice-grow­ing areas and is the main cash crop in somerainfed areas of East and Central java. In 1994the Research Institute for Legumes and Tu­bers (RILET) and CIP analyzed farmers' IPMneeds in the main sweetpotato-growing areasof java. Farmers rated rats, root rot, leaf-feed­ing insects, stemborers, and the sweetpotatoweevil as the most important pests.

In 1986 Indonesia adopted integrated pestmanagement (IPM) as a national policy andbegan· implementing IPM for rice throughfarmer field schools (FFS), based on a modeldeveloped by the FAO Intercountry Rice IPMProgram. That experience provided a foun­dation for expanding the program to horti­cultural and secondary crops. Indonesianfarmers can now learn to become IPM prac­titioners through FFS for chile, cabbage, to­mato, potato, shallot, and soybean. As of1994, FFS for maize, cassava, andsweetpotato, the other main secondarycrops, had not been developed.

1 CIP-ESEAP Regional Office, Bogor, Indonesia.2 Mitra Tani, Yogyakarta, Indonesia.3 Research Institute for Legumes and Tubers, Malang,

Indonesia.

4 Duta Wacana Christian University, Yogyakarta, Indonesia.

198 Program 4

Farmer

Farmers keeping daily calendars appliedbetween 100 and 400 kglha of nitrogen, but noclear relation between the rate of N applica­tion and yield emerged. All four villages par-

Farmers' field research agendaThe field researchers developed an agenda

of issues they wanted to investigate. Theproject team from RILET, Mitra Tani, UKDW,and CIP helped them design, conduct, andevaluate their experiments. These includedagronomic, varietal, and pest managementtrials. Many of the trials were designed to fol­low up issues raised by the recordkeepingexperience, particularly those relating to in­creasing input use efficiency.

(IP Progrom Report 1995·96 199

Field researchers also received training inmethods for monitoring pests, natural en­emies, and diseases. They made weeklyevaluations in the fields of the farmers whowere participating in the daily recordkeeping.The objective of this activity was to developtheir expertise in routine field monitoring andto build knowledge of how insect populationsbehave. This knowledge is the basis for learn­ing to judge whether and when a given in­sect is a pest.

• Weevil-damaged

0 Undamaged

l-

f-- I-_....

[l-

I [~~I--

- lIL

Figure 1. Sweetpotata yields of 45 farmers at six sites in East and Central Java, Indonesia. Each bar represents afarmer; each group of bars represents a site. The last bar on the right represents the global average.Turi, Ngargoyoso, Bendunganjati, Indonesia, 1995 dry season.

o

10

Yield (tlha)

60

20

30

40

50

• Losses from sweetpotato weevil (Cylasspp.), the most serious insect pest, arerelatively minor, even duringthedry season.

• Yield is related to the age of the crop atharvest. With knowledge of the weeklyyield increase, farmers can use currentmarket prices and projected prices tomake better-informed decisions on whento sell to traders (Figure 2).

• There is tremendous variability in profit­ability of the sweetpotato crop, evenwithin a single village. Sharecroppers fre­quently lose money.

• Higher yields are not related to greaterlabor inputs.

• The expenditure for fertilizers and pesti­cides is the smallest portion of money spentfor inputs.

• Farmers producing higher yields tend toearn more than those producing loweryields, indicating that traders are paying ahigher price per ton to farmers who pro­duce more (Figure 3).

• The most promising way to increase in­come from the sweetpotato enterprise, atleast in the short term, is by improving cropmanagement and using inputs more effi­ciently.

33

III

The conclusions from the first varietal trialconducted by farmer field researchers follow:

Farmers from the participating villages areeager to test new varieties. During the first sea­son of collaboration, the field researchers de­cided to exchange elite varieties from eachvillage.

Yield (tlha)

60

50

III III III40 III

III III III III30

IIIIII

20III

II III I III III10 III II

IIIa

13 18 23 28

Harvest age (wk)

Figure 3. Profit vs. yield of sweetpotato. Each paint represents a farmer. Turi, Ngargoyoso, Bendunganjati, Eastand Central Java, Indonesia, 1996 dry seasan. The 1996 exchange rate was Rp. 2,230 = US$l.OO.

Figure 2. Relation between sweetpotato age at harvest and yield. Each point represents a farmer. Turi,Ngargoyosa, Bendunganjati, East and Central Java, Indonesia, 1995 dry seasan.

ticipated in a trial designed to investigate theeffect on sweetpotato yield of urea applica­tion rates between 100 and 250 kg/ha. Thefield researchers and their network of farmercollaborators concluded that the crop was notresponding to urea applications in this range(Figure 4). Farmer researchers are currentlyinvestigating the effect of N application ratesof <100 kglha.

200 Progrom 4

Figure 4. Effect of urea application on yield of sweetpotato in four Javanese villages, Ngargoyoso, Turi,Bendunganjati, and Kradenan, East and Central Java, Indonesia, 1995 dry season.

250

.... -. .

Ngargoyoso

200

The project team developed an experi­mental curriculum and a guide for FFS facili­tators. Course content was drawn from theresults of five seasons of farmer experiments;complementary experiments conducted byIndonesian institutions, CIP, and the Univer­sity of Queensland, Australia; and the litera­ture on sweetpotato agronomy, pathology,and entomology.

(IP Program Report 1995-96 201

The first pilot field school was conductedduring the 1995 dry season in Turi, with anexperienced rice IPM farmer-trainer as facili­tator. Feedback from the participants was usedto improve the curriculum, the activities, andthe training materials. A second pilot schoolwas run in Turi during the 1996 dry season.This field school served as an arena for train­ing the field researchers who were to be­come the first group of sweetpotato FFS fa­ci Iitators.

than an instructor or lecturer, a facilitator actsas guide and mentor to steer participatingfarmers through the FFS learning process. Thefacilitator is either a trained farmer or an ex­tension worker.

Urea (kg/ha)

150

............•......... Bendunganjati......... ............•.....

45

35

25100

55

Yield (tlha)

The field researchers are now testinggermplasm provided by RILET.

Curriculum developmentField schools are based on adult educa­

tion principles that stress the importance oflearning through hands-on activities, withthe field itself the learning laboratory. Rather

• Varieties tend to perform best in their vil­lage of origin. An exception was JegosSuper, which outyielded the best localvariety Bestak in Bendunganjati villageby more than 20 t/ha.

• Turi and Bendunganjati tended to havehigher losses from sweetpotato weevilthan the other villages. The field research­ers attributed that to the heavier soils inthose vi Ilages, and to the practice ofplanting two consecutive crops ofsweetpotato each year.

• Some pests tend to be more of a problemin certain varieties (e.g., white grubs invarieties Kankung and Menthik).

• Some problems seem related to both siteand variety (e.g., root cracking in JegosSuper in Ngargoyoso and Kradenanvillages).

The second field school applied inte­grated crop management ((CM) principlesand practices on an experimental plot. Mar­ketable yield in the FFS plot was 15 t/hahigher than that in neighboring fields man­aged by farmers who were not participatingin the field school.

The key ICM practices included field sani­tation to eliminate sources of insects and dis­eases, selection of healthy planting material,use of tip cuttings, application of organic fer­tilizer and KCI, reduced N application, andhilling-up to minimize soil cracking. Pestmanagement practices were based on weeklyfield observations.

Profile of a Farmer Field School

Sweetpotato field schools cover the entirecropping cycle, beginning with the selectionof planting material. During the crop estab­lishment phase and when harvest time is ap­proaching, they meet weekly. Meetings areheld every 2 wk during the intervening time.

Each FFS has a field of approximately1,000 m2 where participants conduct fieldobservations and collect data. The field ismanaged based on agroecosystem analysisfollowing ICM principles. Participants makeweekly observations throughout the growingseason to learn about the agroecosystem, in­sect population dynamics, and many othertopics. At harvest, yields and damage levelsfrom direct pests (weevi Is, root rot, rats, wh itegrubs) are compared. The economic returnfrom the experimental plot is analyzed andcompared with neighboring fields under tra­ditional management.

Agroecosystem observation, analysis, andpresentation of results is the core activity ofthe FFS. Working in small groups, farmersmake observations of the experimental plot.Participants collect data from ten 1-m2 quad­rats per plot, focusing on factors that workfor and against crop health. They observeplant vigor, numbers of pests and natural en­emies, disease damage symptoms, and otherfield details. Following the observations, thefarmers rJeet to draw what they have just

202 Program 4

observed on large pieces of newsprint, andto examine specimens brought from the field.The drawings indicate the size and stage ofthe sweetpotato plant, the pests and naturalenemies observed, and other salient details.While drawing, farmer, discuss the data theyhave collected and decide on the manage­ment practices to be carried out in the field.A summary of these is added to the drawing.One member of each group presents thesefindings and decisions to the larger group.After each presentation, the floor is openedfor questions and discussion. Management ofthe experimental field is based on the con­sensus reached in the discussion.

Special topics (Table 1) supportagroecosystem analysis by delving moredeeply into specific issues relating to thesweetpotato agroecosystem, IPM principles,and crop health, and they provide an oppor­tunity for farmers to practice basic experimen­tal methods. After the trainer introduces thetopic and explai ns the steps in the process,participants assume active management of theexperiment or activity. Data collection andanalysis are emphasized.

An example of a special topic insweetpotato field schools is the use of flood­ing to eliminate sources of weevil infestation.In this exercise, farmers simulate flooding byplacing infested roots under water for differ­ent periods and then cutting them open tolook for surviving weevils. In another exer­cise, farmers defoliate small sweetpotato plotsat different points in the crop developmentcycle. The objective is to analyze whetherdefoliating insects such as leaf folders and tor­toiseshell beetles, which often provoke pes­ticide applications, decrease yield.

Scaling-up

The field researchers who were trained in thepilot school suggested that the FFS would havegreater credibility among farmers if it were partof the national IPM program. We held a work­shop in October 1996 to describe the experi­ences and outcome of the project to represen­tatives of the national IPM program, universi­ties and national agricultural research institu-

Table 1. Special topics in farmer field schools for sweetpotato (Indonesia,1996).

tions, and NGOs that conduct field school ac­tivities. Participants were asked to analyze threeoptions for the future of the project:

Topic

· Introduction to the farmer field

school

· Heo lthy soil

• Healthy planting meterial

• Setting up an experiment

• Pia nti ng sweetpotato

• Agroecosystem analysis

· Crop health

• Natural enemies

· Pests

· Defoliation experiment

· Diseases

• Weeds: friends or foes?

· Aphids, mites, etc.

• Pesticides: medicine or poison?

• Chemical fertilizers

• Orgonicfertilizers

· Vine lifting

· Esti mating field

· Stemborers

• Sweetpotato weevil

• Planting systems

• Choosing varieties

· Estimating yield

• Harvesting and marketing

sweetpotato

· Field sanitation

(IP Program Report 1995-96 203

The workshop recommended the thirdoption. Since then the national IPM programhas decided to conduct sweetpotato FFS asa follow-up to rice IPM field schools. Farm­ers who have already received rice IPMtraining can extend their experience bydelving more deeply into crop, pest, or dis­ease management problems in rice, or byattending a field school for another crop.During 1997, the sweetpotato field research­ers and members of the project team willtrain 50 rice IPM farmer-trainers to facili-

o1

21

23

5

4

-2

-1

1214

16

18

20

68

10

Wk after pia nting

16

17

7

8

1213

91011

56

34

2

field school session

1. The project should concentrate on refin­ing the model before considering scaling­up.

2. A limited scaling-up process should be de­signed around existing NGOs and farmernetworks.

3. The sweetpotato FFS should become partof the national IPM program's activities.

tate sweetpotato ICM field schools, and thefirst field schools will be initiated.

Rice IPM field schools are concentratedin irrigated rice-growing areas. Therefore,follow-up field schools for sweetpotato con­ducted by the national IPM program willnot reach farmers in rainfed areas who de­pend on sweetpotato as a main source ofincome. To reach those farmers, the projectteam is analyzing prospects for collaborat­ing with NGOs that are working to improvedryland agriculture.

In December 1996, this project won anaward for excellence in methodological in­novation for farmer partici patory researchfrom the Users' Perspectives With Agricul­tural Research and Development (UP­WARD). This project is supported by UP­WARD, the Government of Japan, and ClP'sIntegrated Pest Management Program.

Selected Readings

Braun, A.R. and Dan Edy Priatna. 1994.Suatu tinjauan penelitian tentang hamadan penyakit ubi jalar. Cakara Tani.Edisi Khusus. Desember 1994. FakultasPertanian Universitas Sebelas Maret.Surakarta, Indonesia. p. 18-24.

204 Program 4

Braun, A.R., E. Van de Fliert,C. Wheatley, G. Prain, and Y. Wi dodo.1995. Improving profits fromsweetpotato by linking IPM withdiversification of markets. CIP Circular21 (3):8-15.

Braun, A.R., and E. Van de Fliert. n.d.The farmer field school approach toIPM in Indonesia: User participation.In: Proc. Fifth Annual Conference.Users' Perspectives With AgriculturalResearch and Development,9-12 Dec. 1996, Subic Bay, Philippines.UPWARD, Los Banos, Philippines.

Van de Fliert, E., R. Asmunati, Wiyanto,Y. Widodo, and A.R. Braun. 1996.From basic approach to tailoredcurriculum: Participatory developmentof a farmer field school model forsweetpotato. In: Into action research:Partnership in Asian rootcrop researchand development. UPWARD, LosBanos, Laguna, Philippines.

D.P. Zhang!, A. Golmirzaie!, G. Cipriani!, A. Panta!, M. Ghislain!,N. Smit!, I. RetyZ, and D. Michaud2

Developing Weevil Resistance inSweetpotato with Genetic Transformation

1. Developing a regeneration and transforma­tion system protocol for sweetpotato,

2. Identifying appropriate protease inhibitorsfor sweetpotato weevil, and

3. Producing transgenic plants that carry for­eign protease inhibitors.

Regeneration and Transformation System

C1P Progrom Report 1995-96 205

The bottleneck in developing transgenicsweetpotato has been the lack of a reliableregeneration system, because regeneration isstrongly genotype dependent. Cultivars vary

Sweetpotato plant regenerationWe have developed an efficient regenera­

tion protocol and Agrobacterium-mediatedtransformation system. Using this system, wehave been able to regenerate and transformmost of the sweetpotato cultivars tested.

In this article, we summarize research atCIP and its collaborating institutions to de­velop a transgenic sweetpotato with proteaseinhibitor genes. This work is divided into threeparts:

Genetic transformation with genes that en­code protease inhibitors (PI) is a novel ap­proach to creating weevil resistance insweetpotato. Foreign genes that encode pro­tease inhibitors have been introduced intotobacco, tomato, strawberry, potato, andmany other crops to control a range of insectpests. These proteins bind to proteases in themidgut of the insect, thus affecting the insect'smetabolism.

ronment interaction and low heritability gen­erally preclude the use of conventional breed­ing techniques.

Host resistance is an important componentin successful integrated pest management(IPM). ClP's experience in Caribbean coun­tries demonstrated that use of less susceptiblecultivars significantly contributed to the ef­fect of IPM. The search for weevil resistancestarted 50 years ago, but the level of resis­tance found in sweetpotato and its wild rela­tives is rather low. A large genotype by envi-

The cryptic feeding habit of thesweetpotato weevil larvae and the nocturnalactivity of the adults make it difficult to de­tect sweetpotato weevil infestations. Approxi­mately 80-90% of the weevil populationwithin vines and roots is distributed belowthe soil surface. These factors limit the effec­tiveness of chemical insecticides applied forweevil management.

1 CIP, Lima, Peru.2 Horticultural Research Center, Laval University, Quebec,

Canada.

Weevil damage imparts a characteristicturpentine odor to the roots, which renderseven slightly damaged roots unfit for humanconsumption. Larvae also feed inside thevines.

Crop loss of sweetpotato (Ipomoea batatas (L.)Lam.) caused by insect damage is the mostimportant problem in the field. Although theimportance of pest species varies regionally,sweetpotato weevil (Cylas spp,) is the mostimportant threat worldwide. The weevils C.formicarius (Fabricius) and C. puncticollis(Boheman) are the most destructive. Larvaeof this pest tunnel through storage roots, re­sulting in major damage and economic yieldloss. Production losses often surpass 60% andcan reach 100%.

Table 1. Regeneration rate of sweetpotato cultivars from complete leaf using CIP-developed protocol.

significantly in their regeneration successes.Therefore, we conducted a series of experi­ments at CIP to modify the regeneration me­dia and to standardize protocol to improveregeneration efficiency.

Two pathways for sweetpotato regenera­tion-somatic embryogenesis and organogen­

esis-have been explored. So far, our regen­eration is achieved mainly by shoot organo­genesis from leaves, roots, and stem intern­odes. We have regenerated most cultivarstested. Table 1 lists the ones that have beensuccessfully regenerated at ClP, even thoughthe regeneration rate remains genotype de­pendent. Meanwhile, we are actively explor­ing use of somatic embryogenic suspensioncultures, which will eventually improve theefficiency of regeneration.

All tested cultivars were obtained from thein vitro gene bank maintained at CIP. Plantswere propagated in vitro at 25 ± 2°C underfluorescent light (45 uEm·zs 1) with 16 h pho­toperiod. Using explants of stem segmentsand complete leaves, we achieved direct re­generation through shoot organogenesis us­ing a two-stage regeneration protocol. In gen­eral, we found that the protocol using com­plete leaves gave the best regeneration rate.

Transformation through A. tumefaciens

Plasmid description. We tested the trans­formation system using two plasm ids. Onewas pBI121 plasmid containing GUS (fJ-glu­curonidase), cecropin (encoding cecropin

Cultivor

Jewel

Chugoku

PI 318846-3

Rusenyo

Mabrouka

Tanzania

Huarmeyano

206 Program 4

proteins that have activity against bacteria),and NPTII (neomycin phosphotransferase)genes. The other was pClPS plasmid contain­ing NPTII and WCI-3 genes. WCI-3 encodeschymotrypsin inhibitor from winged bean(Psophocarpus tetragonolobus). Plasmidswere transferred to A. tumefaciens byelectroporation.

Culture of bacteria. Agrobacteriumtumefaciens was subcultured and incubatedat 28°C for 48 h. Isolated colonies were trans­ferred to a yeast-mannitol liquid medium andincubated at 28°C for another 48 h. Bacteriaconcentration in the liquid medium was de­term ined by spectrophotometry. Bacteriawere then inoculated in Erlenmeyer flaskscontaining 25 ml of liquid potato propaga­tion medium.

Transformation. Explants were excisedfrom the top of young in vitro plants and in­oculated in the liquid potato propagationmedium at 25°C. Inoculated explants weretransferred to batata propagation media andco-cultured at 25°C for 2-3 d. After co-cul­ture, explants were transferred to differentregeneration media depending on the typeof explants.

Using this transformation system, we haveobtained 70 putative transgenic lines with thececropin gene from cultivars Huachano, Re­gal, and Jewel. The GUS assay and Southernblot have confirmed the insertion of the GUSgene into the genome of sweetpotato (Figures1 and 2). About 300 putative transgenic lines

Regeneration rate (%)

70.043.5

28.6

10.010.0

7.85.0

(IP Program Report 1995-96 207

c10 11 12 13 14

8A1 2

Figure 2. Southern blot analysis of DNA isolated from sweetpotato cultivars. The DNA was digested with Hind III.Lane 13 is 50 pg of plasmid containing GUS gene. (A) Huachano plants transfarmed (via A. tumefociens)with Ca2Att gene construct (lane 2 = control plant, lanes 3-5 show bands containing the GUS gene). (B)Jewel plants transformed (via A. tumefociens) with pBI121 containing the GUS gene (lane 8 = controlplant, lanes 7-8 show bands containing the GUS gene). (e) Chugaku plants transformed (via A.rhizogenes) with pBIG121 containing intron-GUS gene (lane 9 = control plant, lanes 10-11 show bandscontaining the intron-GUS gene).

Figure 1. Expression of GUS (f3-glucuronidose) gene in the leof of transgenic sweetpotato Chugoku.

with WCI-3 genes were obtained from culti­vars Chugoku, Huachano, Huarmeyano, PI­318846-3, Jewel, Mabrouka, Morada Inta,and Tanzania.

These resu Its show that the A. tumefaciens­mediated transformation system works effi­ciently on sweetpotato. We now have thetechnical ability to transform and regeneratemost sweetpotato cultivars, including the onesmost widely grown in Asia and Africa.

Identification of AppropriateProtease Inhibitors

To select efficient protease inhibitors forsweetpotato weevil control, we need to knowwhich proteolytic enzymes are used by theseweevil species for the hydrolysis of dietary pro­teins. As a first step, midgut proteases were ana­lyzed in larvae and adults of three Cylas spe­cies, C. formicarius, C. brunneus, and C.puncticollis. C. formicarius was collected insouthern China and Indonesia, whereas C.brunneus and C. puncticollis were sampled inUganda. Characterization of the weevil diges­tive proteases was conducted at the Horticul­tural Research Center (CRH), Laval University,Quebec, Canada. The study was done usingstandard quantitative assays and electrophoretictechniques developed at CRH for the analysisof protease-protease inhibitor interactions.

Digestive protease activity in all three spe­cies was partly accounted for by sets of stage­specific protease species. Larvae and adu Itsof all three species were shown to use a mix­ture of exopeptidases and endopeptidasesactive primarily in the alkaline pH range.

High caseinase activity was detected in theinsect samples at pH 10-11, whereas barelydetectable activity was measured in mildlyacidic conditions (pH from 5 to 7), even inthe presence of reducing agents such as 1­cysteine or di-thiothreitol. This observation,which suggests the predominance of serine­type proteases in the midgut of all three spe­cies, was confirmed by inhibition assays.

Whereas inhibitors such as cystatins (cys­teine-type inhibitors) and pepstatin (aspartyl-

208 Progrom4

like inhibitor) showed no effect, a significantfraction of the caseinase activity measured atpH 10.5 was inhibite.d in reducing conditionsby the serine-type protease inhibitorsphenylmethylsulfonyl fluoride (PMSF) andsoybean (Phaseolus angularisl trypsin inhibi­tor (SSTI). Interestingly, the inhibitory spec­trum of SSTI against the midgut proteases wasapparently larger than that of endogenousinhibitors in sweetpotato (Figure 3), suggest­ing the potential usefulness of this inhibitorin weevil control.

At this point, we are not clear whether allthe serine endopeptidase activity in weevilwas blocked by SSTI, because the insect mayhave certain proteases that are insensitive tothe plant trypsin inhibitors. A partial inhibi­tion, however, is enough to cause develop­mental alterations as demonstrated in manyother Coleopteran insects. Foreign (nonhost)inhibitors such as recombinant SSTI and cow­pea (Vigna unguiculata) trypsin inhibitor(CpTIl are promising candidates for the de­velopment of transgenic sweetpotato withresistance to Cylas weevils. Therefore, SSTIand CpTI genes were selected and are beingused to develop weevil-resistant transgenicsweetpotatoes.

Production of Transgenic Plants

The first transgenic sweetpotato with the cow­pea trypsin inhibitor was developed by AxisGenetics Ltd., U.K. Since the gene constructCpTI encodes a Sowman-Sirk trypsin inhibi­tor, our objective is to determine whether thetransgenic lines with CpTI will demonstrateenhanced resistance to C. formicarius.

Ten transgenic lines of cv. Jewel were ob­tained through a collaborative project be­tween Axis Genetics Ltd. and CIP, and sevenof them had the cowpea trypsin inhibitor. Theother three Iines had both the CpTI gene andPCG gene, which encodes snowdrop lectin.

We have propagated these transgenicplants in an isolated screenhouse followingPeruvian biosafety guidelines. Thesetransgenic lines will be evaluated in Cuba andChina using a screenhouse and field bioassay.

Figure 3. Response of (ylas spp. midgut proteinases to the action of class-specific proteinase inhibitors. Proteaseactivity was measured with larval extracts at pH 10.5, using casein as a substrate. Data representrelative residual activity (%)± SE, compared with a control for which no inhibitor was added (100%activity). HEC = hen egg cystatin; OCI = oryzacystatin I; PMSF = phenylmethylsulfonyl fluoride;SBTI = soybean trypsin inhibitor (Kunitz-type).

0 C. puncticol/is

SSTII C. brunneus

-

SMSF o C. formicarius

-

GCI

-

HEC

-

Pepstatin

-

Control

I

100

Genetic transformation plays an importantrole in enhancing sweetpotato germplasm. Re­cent progress in developing a transformationsystem and identifying candidate protease in­hibitors has established an essential base forcreating host resistance for sweetpotato wee­vil. The combination of several serine PI insweetpotato through transformation would mostlikely produce a durable defense mechanismagainst sweetpotato weevil.

constitutive expression of the PI transgenesin all tissues of the plant.

ClP Progrom Report 1995-96 209

Conclusions

Serine protease inhibitors such as 5BTI fromsoybean and CpTI from cowpea were identi­fied as candidate inhibitors for transformation.Transgenic cv. Jewel sweetpotato expressingCpTI is being propagated for field evaluationfor weevi I resistance. Co-transformation withseveral serine PI and cystatin PI genes will beapplied to construct a combined defensemechanism against sweetpotato pests.

I I I 1

20 40 60 80

Residual proteinase activity (%)

a

Biochemical analyses provided evidencethat sweetpotato weevil larvae, which feedmainly on storage roots, and adults, whichfeed mainly on foliage, both use similar di­gestive proteolytic systems. The use of root­specific promoters appears unnecessary anda constitutive expression of the recombinantinhibitors is preferred. Therefore, CIP is us­ing the cauliflower mosaic virus 355 promoter(CaMV355) for all gene constructions. Theexpression of this promoter should lead to a

Meanwhile, we are incorporating a newplasmid, pAD1289, into A. tumefaciensLBA4404. It enhances transformation effi­ciency as reported in tobacco, cotton, andother crops. We are using three PI genes forsweetpotato transformation: OCl, which en­codes a cystatin of rice; CpTI, which encodesa Bowman-Birk trypsin PI of cowpea; and5BTI, which encodes a Kunitz-type trypsin PIfrom soybean. The spectrum of these inhibi­tors covers the major digestive proteases ofsweetpotato weevils (CpTI and SBTI), and ofother pests of sweetpotato (Gel).

Selected Reading

Chalfant, R.B, R.K. jansson, D.R. Seal, andj.M. Schalk. 1990. Ecology andmanagement of sweetpotato insects.Annu. Rev. Entomol. 35:157-180.

Michaud, D., N. Bernier-Vadnais,S. Overney, and S. Yelle. 1995. Consti­tutive expression of digestive cysteineproteinase forms during development ofthe Colorado potato beetle, Leptinotarsadecem/ineata Say (Coleoptera:Chrysomelidae). Insect Biochem. Mol.BioI. 25:1041-1048.

210 Progrom4

Newell, CA., j.M. Lowe, A. Merryweather,L.M. Rooke, and W.D.O. Hamilton.1995. Transformation of sweetpotato(Ipomoea batatas (L.) Lam.) withAgrobacterium tumefaciens andregeneration of plants expressingcowpea trypsin inhibitor and snowdroplectin. Plant Sci. 107:215-227.

1 Program Leader, ClP. Lima, Peru.

Mahesh D. Upadhya1

The collection of pathogen-tested germplasmincreased to 14,000 with the addition of 198new clones. In addition, 96 new clones arein the process of being cleaned up by ClP­contracted institutions in Australia, Austria,and Luxembourg.

Management and Distribution ofPathogen-tested Germplasm

(IP Progrom Report 1995-96 21 1

Pro

Eighteen new cultivars released in sevencountries consisted of 13 clones developedby ClP under different projects and 5 clonesfrom germplasm being maintained and dis­tributed by ClP.

and roots under severe water stress, whereasclone ClP-440034 had twice the foliage yieldof Tanzania.

REPORT

Research and development activities in 1995­96 in Program 5 continued to focus on threemajor areas: (1) management and distributionof pathogen-tested germplasm, (2) multipli­cation and distribution of clean planting ma­terial, and (3) breeding for and evaluation ofhybrid TPS families. In addition, notableprogress has been achieved in breeding andselecting for frost and drought tolerance.PROINPNCIP collaboration made it possibleto select four new frost-tolerant potato clonesthat are also wart resistant, and three drought­tolerant clones from germplasm supplied tothis project. Selection for drought tolerancein sweetpotato germplasm indicated that cv.Tanzania was the highest producer of foliage

Propagation andCrop Management

PROGRAM

Information on the worldwide distributionof germplasm since 1990 has been includedin a database that is now accessible to all ClPscientists in Lima. This database will be madeaccessible to all regional scientists in 1997.

Multiplication and Distribution ofClean Planting Material

Alternate methods for the distribution of cleanseed of selected cultivars (native and im­proved ones) to farmers were developedthrough the diffusion of rustic nurseries byPROI NPA. More than 300 of these nurserieswere established in different ecoregions ofBolivia.

Rapid multiplication techniques were veri­fied with the Mariano Marcos State Univer­sity, Ilocos Norte, Philippines. Seed tubersderived from apical stem and sprout cuttingscan be produced on-station and sold to farm­ers through the informal seed system.

A major potato seed multiplication activ­ity was carried out at the ClP/KARI seed unitfor Rwanda in 1995 as part of the "Seeds ofHope" intercenter project. The seed unit pro­duced and supplied to Rwanda 560 kg (ap­proximately 6,400 tuberlets) of its three ma­jor cu Itivars: Sangema, Cruza, and Mabondo.This unit also supplied 45,000 minitubers andin vitro plantlets to target NARS in Kenya,Uganda, and Ethiopia.

Breeding for and Evaluation ofHybrid TPS Families

Major achievements in this area involved suc­cessful evaluations of hybrid TPS families pro­duced by ClP under final trials in Egypt, In­dia, Bangladesh, and Vietnam. The results of144 demonstration trials carried out in 1995­96 in Munshiganj, Jassore, and Bogra districtsof Bangladesh showed that hybrid TPS fami­lies HPS-11/67 and HPS-7/67 had the best per­formance. About 16 kg of TPS was producedat the Debiganj Seed Station of TCRC,Bangladesh.

There has been a progressive increase inarea planted from TPS-derived planting ma-

212 Progrom5

terial in Bangladesh, India, and Vietnam. Statedepartments of agriculture/horticulture and anumber of NGOs are now involved in dis­seminating technology of TPS utilization forpotato production to farmers.

The project "Field-Testing of True PotatoSeed in Lowland Tropics," funded by theAsian Development Bank, has achieved itsobjectives in all the participating countriesin the first phase. In the rice-based croppingsystem of the Red River Delta (RRD) in Viet­nam, all original plans and projections werecarried out to a large degree, and the TPStechnology may now be considered as a per­manent feature of the RRD cropping system.This unexpectedly rapid success has beenpossible because the TPS technology met aspecific need of an entire region by offeringan alternative to a discredited system that re­lied on degenerated tuber seed of question­able origin.

From the beginning, the project had thesupport of the research community and sci­entists from the Vietnam Agricultural ScienceInstitute (VAS!) and political leaders of sev­eral provinces in the RRD. The presence ofClP scientists from Lima and from the regionaloffice in Indonesia at crucial moments in thedecision-making process was one of severalimportant factors in the success of this project.Two ofthe hybrid TPS families (HPS-11/67 andHPS-7/67) selected under the project in theRRD have been released as Hong ha-2 andHong ha-7 (RRD-2 and RRD-7). Technicalsupport and parental lines have been pro­vided to VASI to begin hybrid TPS produc­tion in the RRD and Dalat.

Evaluations of new hybrid TPS familieswere carried out under four contrastingthermo-photoperiodic conditions. Promisingfamilies showing stability for yield across thefour conditions have been identified. One setwith early bulking (75 days after transplant­ing) is for subtropical regions and the secondset is for Latin American countries where highyields can be obtained at 90 days after trans­planting.

TPS quality tests developed at OP-Limahave consistently predicted relative field es­tablishment and performance. The dormancyrelease procedure developed at OP-Lima hashelped to improve the emergence and fieldperformance of hybrid TPS.

Studies were carried out on the reproduc­tive biology of potato in clones from 320

andigena accessions in the germplasm col­lection held at CIP. Characters studied in­cluded style/stigma morphology, pollen qual­ity and quantity, seed/berry after selfing, and1OO-seed weight as well as the proportion ofdifferent seed types with respect to embryomorphology. Data are being processed andwill be entered into OP's database.

(IP Program Report 1995-96 21 3

Simultaneous Selectionfor Yield and Stability in HybridTrue Potato Seed Families

M. Upadhya and R. Cabello!

For crop performance trials across diverse en­vironments, where genotype x environment(GE) interactions occur, a selection criterionthat taKes GE interaction into considerationdoes not exist. Kang and Magari (in 1995),however, came out with a BASIC program forcalculating stability and yield stability for usein selecting high-yielding stable genotypes,especially in short-term trials that allow theuse of GE interactions,

Although hybrid true potato seed (TPS)families do not exactly fit the definition of agenotype as a unit among genotypes sub­jected to evaluation, efforts have been madeto use Kang and Magari's program for theselection of high-yielding and stable TPS fami­lies. Two sets of TPS families were grown astransplants for two seasons at two altitudesand the data were analyzed using the STABLEprogram, The results are presented in this ar­ticle with a view to bringing out the value ofthis program in helping to select high-yield­ing stable TPS families in short-term trials.However, the final test will be to send theseselected families to collaborating NARS in dif­ferent agroecologies for trials to confirm se­lection results from trials in Peru. If the re­sults of international trials confirm the primaryselection using the STABLE program, thenshort-term trials within Peru will help us re­duce the number of TPS families to be sent toNARS for their evaluation, thus saving valu­able resources.

This STABLE program could also serve asa tool to evaluate parental Iines for their con­tribution to high-yielding stable hybrid fami-

1 CIP, Lima, Peru.

214 Progrom 5

lies. In this study, we tried to use commonselected male parents with a number of se­lected female clones to generate hybrid TPSfamilies, These hybrid TPS families were thenevaluated during two seasons at two differ­ent altitudes under contrasting thermo-pho­toperiod conditions. Analysis of the data us­ing the STABLE program has not only allowedus to select high-yielding stable TPS families,but has also helped in comparing the contri­bution of female parents of the hybrid TPSfamilies to yield and stability. This article pre­sents and discusses the results.

Materials and Methods

Seedlings from hybrid TPS families wereraised in plastic trays containing substratechemically sterilized with methyl bromide.The substrate is a mixture of two parts peatmoss and one part sand. A fertilizer supple­ment for NPK was added to 100 kg of sub­strate at the rate of 60 g of ammonium ni­trate, 250 g of single superphosphate, and 50g of potassium sulfate,

In each tray (33 x 23 x 5.5 cm), 100 seedswere sown at O,5-cm depth, covered with finepowder of the substrate, and watered with aspray can. Seedlings were raised in nethousesfor the fi rst 3 wk after seed sowing and thenhardened under field conditions for 1 wk be­fore being transplanted bare-rooted in thefield. One foliar application of 3% ammoniumnitrate was given to the seedlings 20 dafterseed sowing,

Two sets of hybrid TPS families were usedfor the trials, One set of famil ies was selectedfor distribution to countries where harvesting

was to be done 90 d after transplanting andwhere segregation for tuber skin color is notimportant. The TPS families in this set weresegregating for skin and eye color; otherwise,all of them had uniform tuber shape and flesh

color.

The second set of TPS families was meantfor distribution to countries where the cropwas to be harvested 75 d after transplantingand where uniformity of skin color was nec­essary. These TPS families were uniform fortuber skin, flesh color, and tuber shape.

Two trials for each of the sets of TPS fami­lies were conducted in CIP fields at La Molina(247 m) and two trials at Huancayo (3,225m). Trials at La Molina were conducted dur­ing winter and spring and at Huancayo dur­ing spring and summer of 1995-96. Each trialhad three replications with four rows of 20plants each. There were 30 cm betweenplants and 90 cm between rows.

The crop was harvested after 15-20 d ofhaulm cutting and data were recorded on tu­ber yield/plot, which was then converted intot/ha.

In the field, NPK was applied as 200 kg N,185 kg P, and 120 kg K. Half the dose of ni­trogen as ammonium sulfate and full dosesof P and K as single superphosphate and po­tassium sulfate were applied before trans­planting. The remaining half dose of nitro­gen was split again and 50 kg was given asurea at the time of first earthing at 35 daftertransplanting and the remaining dose of 50kg as urea was applied at the second earthingat 50 d after transplanting.

The data were subjected to statisticalanalysis using the STABLE program for cal­culating stability and yield stability for thecomparative performances of two sets of hy­brid TPS families as well as for simultaneousselection for yield and stability in perfor­mance trials.

Results and Discussions

Table 1 presents the average yield data forthe first set of hybrid TPS families meant for

Latin American countries, with the simulta­neous selection for yield and stability analy­sis given in Table 2. Out of a total of 22 TPSfamilies evaluated, 11 were selected by theprogram for their yield and stability. These11 TPS families are ranked from 1 to 11 basedon their average yields.

Similarly, Table 3 presents the averageyield data for the second set of hybrid TPSfamilies meant for global distribution, with theanalysis for the simultaneous selection foryield and stability given in Table 4. A total of35 TPS families were compared, keeping cul­tivar Desiree as the check grown from certi­fied tuber seed of 30-50 g. Out of 35 familiesevaluated, 19 were selected by the programbased on the YS(i) statistic.

The TPS families in the first set had fourmale clones that were crossed with 15 femaleclones to generate 22 hybrids. Out of the 11families selected by STABLE, seven had themale clone 104.12 LB in common, whereasthree had R-128.6 and on Iy one had 4.1 01 asthe male parent. Atzimba as the female par­ent combined well with R-128.6 and 104.12LB, but not with 7Xy'1, to give high-yieldingstable families.

The clone LT-8 was a good general com­biner because it produced selected familieswith all three male parents. Meanwhile, 1­1035 proved to be a good combiner with R­128.6 but not with 104.12 LB. WhereasChiquita did not prove to be a good combiner,clones CFK-69.1, MF-II, and Serrana pro­duced stable-yielding families with the clone104.12 LB, a good general combiner.

Among the TS clones crossed with thecommon male 104.12 LB, only TS-6 and TS­14 have produced stable-yielding families.

The results also indicate that to evaluatethe performance of new male parents, cloneslike Atzimba and LT-8 as common femaleparents could provide effective selection ofthe best pollinator clones, whereas the maleclones R-128.6 and 104.12 LB could be usedto select good-performing female clones in abreeding program.

[IP Program Report 1995-96 21 5

Table 1. Performance (yield in t/ha) of the first set of hybrid IPS families as transplants for Latin America intrials at La Molina and Huancayo (1995 and 1996).

33.1

27.338.317.035.334.133.229.029.234.934.931.332.2

36.223.128.525.238.5

26.624.5

22.334.3

31.3

Summer

Huancayo

29.612.617.717.519.812.2

15.218.613.719.516.117.521.917.212.716.118.321.613.616.011.419.4

17.2

Spring

5.68.9

9.8

12.313.312.812.912.012.59.59.2

17.89.3

12.013.314.5

10.98.6

11.8

8.8

Winter

The clone TPS-113 was the originalandigena clone selected for its excellent gen­eral combining ability. But the hybrid fami­lies produced using this clone as the maleparent showed some segregation for tuberskin color under certain cool climates. There­fore, after selfing it and growing the progenyfrom seed> 1/16" and with A type embryo,TPS-13 was selected as a new pollinatorclone, which proved to be as good a generalcombiner as the parental clone TPS-113, with-

La Molina

8.9

19.016.611.5

15.8

11.815.7

Spring

Atzimba xR128.6

Family

Simi larly, Table 4 also provides results forthe effective selection of parental clones forthe production of stable-yielding hybrid TPSfamilies. The first six families had alreadybeen evaluated under different agroclimatesof Asia and had proved their value as high­yielding stable TPS families. The two polli­nator clones, TPS-13 and TPS-67, were ex­cellent general combiners in studies made inIndia by the CIP team.

216 Progrom 5

Table 2. Simultaneous selection for yield (t/ha) and stability in the first set af hybrid TPS famillies inperformance trials.

The clone LT-8 with both the male clonesproduced hybrid families that were selected,

elP Progrom Report 1995-96 21 7

Similarly, in the first set, 1-1035 as a fe­male with R-128.6 got selected. In the sec­ond set, however, in combination with eitherof the two pollinators, TPS-13 and TPS-67,the TPS families were not selected.In the second set, the TPS family Chiquita

with TPS-113 was selected, whereas in thefirst set Chiquita as a female with two of themale parents was not selected.

out showing segregation for tuber skin color.TPS-13 also produces a higher amount ofpollen and has pollen fertility above 80%.

Table 3. Performance (yield in t/ha) of the second set of hybrid TPS families as transplants for globaldistribution in trials at La Molina and Huancoyo (1995 and 1996).

La Molina Huancayo

Spring Winter Spring Summer

804 9.5 604 24.37.7 9.3 5.7 25.05.9 ILl 4.9 28.67.0 15.7 4.1 24.54.7 13.2 5.9 29.59.3 12.6 4J 24.88.7 10.4 7.l 24.15.3 10.5 4.5 26.97.l 12.1 6.8 24.0

10.7 10.1 3.1 18.99.0 8.0 2.9 18.2

14.3 9.7 4.8 24.312.6 11.1 7.9 26.39.8 8.3 4.1 18.75.7 3.7 0.9 11.09.2 6.5 3.9 19.7

11.3 9.4 4.2 18.89.6 12.4 5.9 23.89.0 10.3 8.2 28.3

12.3 lU 7.1 28.09.8 12.4 5.8 23.37.8 10.2 7.4 24.14.3 12.2 10.0 28.36.1 10.7 3.5 19.69.4 13>1 4.9 29.7

13.9 13.0 8.8 24.36.1 lOA 5.8 25.16.1 9.9 8.6 24.39J 10.3 3.6 19.38.7 10.3 2.6 18.08.7 10.3 3.1 25.5

ILl 5.3 3.3 27.410.2 10.0 2.0 15.4

6.1 11.0 10.3 26.96.3 10.5 8.6 24.5

23.7 20.7 26.8 17.5

Family

1. HPS-7/672. HPS-7/133. HPS-25/134. HPS·I/67

HPS-1/13HPS·1I/13Aracyx TPS·l

8. CEW-69.1 xTPS-1139. Chiquita xTPS·1l3

C320lM86B xTPS-67C320lM86 BxTPS·13C914lM86B xTPS-13

13. C914lM86B xTPS-6714. 1-1035 xTPS-6715. l-l035xTS·1316. Katahdin xTPS-1317. Katahdin xT5-6718. IT-8 xTP5-1319. IT-8xTPS-6720. Serrano xTPS·13

30.31. 3xTPS-1332. TS-14 xTPS-6733. TS-14 xTPS-1334. Atzimba xTPS-1335. Atzimbo xTPS-6736. Desiree (check)

DMS 0.05 =3.66, CV % = 18.5.

21 8 Program 5

Fcunily Yield Yield Adjustment Adjusted Stability Stability YS(i}"

rank to rank variance fating

1- HPS-7/67 12.1 17 - I 16 2.1 0 16+

2. HPS-7/13 11.9 16 -I 15 5.6 0 15+

HPS-25/13 12.6 22 1 23 39.6 - 8 15+

4. HPS-l/67 12.8 23 1 24 32.9 -8 16+

HPS.. l/13 13.3 28 1 29 60.5

6. HPS-II/T3 12.8 25 1 26 0 26+

7. Alacy xTPS-113 12.6 21 1 22 O.S 22+

8. CEW-69.1x TPS-lT3 11.8 12 11 -S

9. Chiquita xTPS-113 l2.5 20 1 21 +

10. C320LM86hTPS-67 10.7 9 - 2 7 21.8 - 8

11. C320lM86B xIPSc13 9.5 3 - 2 1 12.9

12; C914 LM868 xTPS-T3 13.3 27 1 28

13. C914LM86Bx IPS-67 14.5 33 2 35 5.3 35+

1A. Icl035xTPSc6? 10.2 7 - 2 15.0

15.1-1035 xTS·13 5.3 1 ·3 - 2 47.6 -TO

16. Katahdin xIPS·13 9.8 4 -2 2 1 0

IT Katahdin x15-67 11.0 10 -I 93 12.9 26 1 27 0.8

14.0 31 33 18.3 29+

14.8 34 2 8.812.S 24 1 2S 1.312.4 19 113.7 30 1 31 23+

10.0 614.3 32 2 -815.0 35 7.511.8 14 - 1 11.0T2.8 18 -1 17.010.6 8 -2 6

9.9 5 -2 3 17.5 - I

31 TS-13 xTPS-13 11.9 15 - 1 14 12.4 0 14

32.• TS-14xTPS-67 11.8 13 - I 12 58.7 ·833. TS- ]4xTPS·] 3 9.4 2 - 2 0 50.5 - 8 - 8

34. Atzimbo xTPS-13 13.6 29 1 30 34.1 -8 22+

3S. AtzirnbaxTPS·67 11.8 11 - I 10 7.3 0 10

36. Oesiree (check) 22.2 36 3 39 411.7 -8

12.3

1.5

o.

(IP Program Report 1995-96 21 9

Table 4. Simultaneous selection for yield and stability in first set of hybrid TPS families in performance trials.

as was the case in the first set, thus furtherproving the value of this clone. Serrana as afemale clone was also a good combiner withthe two male clones in the second set (Table4), as it was in the first set (Table 2).

Although Atzimba with TPS-13 was se­lected, the family with TPS-67 as the maledid not perform well.

Among the TS clones, TS-6 with TPS-1 3was also selected, as it was in the first set with104.12 LB as the male parent. However, TS­14 in combination with TPS-13 and TPS-67did not produce stable-yielding families,whereas in the first set it was selected with104.12 LB as the pollinator clone. The cloneTS-9 in combination with TPS-113 and TPS­67 produced hybrid families that were se­lected, but as in the first set, the family TS-9 x104.12 LB was not selected. Likewise, thehybrid families with Katahdin as the femaleparent did not perform well. The clone CEW­69.1 did not perform well in either of the sets.

Conclusions

These results will allow us to send fewer hy­brid TPS families to our collaborators in dif­ferent countries who are experimenting with

220 Program 5

TPS technology. In addition, the performancevalues of female and male clones used asparents wi II be used to further improve theparental clones, and the selected clones willbe used as testers for the newly selected geno­types.

Use ofthe STABLE program to evaluate theperformance of hybrid TPS families hasproved its worth both as a tool to determinethe parental values of the clones used as par­ents for the hybrid TPS fam iIies and for theselection of high-yielding stable familiesbased on short-term performance trials. Com­parison by NARS of the data from trials un­der different agroecologies will provide thefinal proof of the usefulness of the STABLEprogram as a tool for the selection ofTPS fami­lies in short-term trials.

Selected Reading

Kang, M.S. 1993. Simultaneous selectionfor yield and stability in crop perfor­mance trials: Consequences for growers.Agron. J. 85:754-757.

Kang, M.S. and R. Magari. 1995. STABLE: Abasic program for calculating stabilityand yield-stability statistics. Agron. J.87:276-277.

Temperature and Moisture AffectDormancy and Deterioration ofTrue Potato Seed During Storage

N. Pallais and R. FalconI

True potato seed (TPS) lots with 90% germi­nation or better, when tested in the labora­tory, often fail to emerge in the field. The prob­lem is that newly harvested TPS are dormant,and the nature and environmental control ofTPS dormancy is not well understood.

TPS dormancy ceased to be a problem inclonal breeding after 1961 when it was foundthat gibberellic acid (GA) could easily be ap­plied to promote germination. But in spite oftreatment with GA, emergence of dormantseeds decreases considerably as the tempera­ture approaches 25°C. Moreover, seedlingsof dormant seeds that are induced to germi­nate with GA produce significantly less fo­liage dry matter (DM) than seedlings pro­duced by dormant seeds.

Before the discovery of GA as a "solution"for TPS dormancy, it had long been knownthat new TPS did not germinate as well asolder seeds. This study examines the relation­ship between storage conditions and dor­mancy of TPS with respect to its sowing value.

Our work showed that dormant TPS ofvariety Serrana (Solanum tuberosum) germi­nated readily at 20°C or below, whereas non­dormant seeds germinated readily at 27°C orabove. High storage temperature coupledwith low seed moisture content (SMC) re­duced the period of storage required for los­ing TPS dormancy from 18 to 4 mo.

Research to determine the applicability ofthese results to open-pollinated TPS of theancient Peruvian potato cultivar Ccompis (S.

1 CIP, Lima, Peru.

tuberosum subsp. andigena) was deemednecessary because of the increasing demandfor its use by small farmers in the Andes ofPeru. The objective of the present study wasto determine the effects of increasing tempera­ture, SMC, and time in storage of freshly har­vested TPS on germination and emergencefrom soi I under different temperatures.

Materials and Methods

Experiments were conducted at CIPwith open­pollinated seeds provided by Semilla eInvestigacion en Papa (SEINPA). The TPS wereproduced according to the recommended prac­tice for high-quality seed, in a large plot of cul­tivar Ccompis grown for basic seed tuber pro­duction in Cusco (3,600 m above sea leve!), Peru.

After harvesting the mature berries, the TPSwere washed and dried in tf"]e shade untilreaching 7.3% SMC (dry weight basis). About12.5 kg of TPS were separated into large(51 %) and small (49%) lots using a round­hole screen at 1.46 mm over a seed shakerfor 4 min. Large TPS were separated with aseed blower into high- (63%) and low-den­sity sublots. Only high-density TPS weresampled at random for this study.

The treatments were prepared by dryingTPS sealed with fresh silica gel at 22°C andmonitoring SMC until the desired moisturelevels were achieved. TPS were immediatelyhermetically sealed in aluminum packages at3.4,4.2, 5.1, 6.1, and 7.3% SMC and storedat 15, 30, and 45°C. Each treatment was com­posed of five random samples of 1 g eachand packaged separately for opening duringeach evaluation period.

(IP Program Report 1995-96 221

222 Program 5

92 ns86 ••* ns50 ns ns0 *** ***

0*.

6 Lo Q

1 ns ns1 ns ns

20 ns46 *** ns52 ns

***

38 ns65 *** ns81 ns78 *** ns87 *** ns***

environment was held constant at 27°C, un­ti I the 8th day when it was lowered to a con­stant of 17°C. Water was added as needed.The germinating TPS received laboratory lightand higher temperature (22°C) only for about20 min during evaluations. Germination waschecked dai Iy for 16 d after sowing (DAS) andgerminated seeds were removed at first sightof radicle emergence. Percentages of germi­nation at 8 and 16 d are presented to sum­marize the results (Tables 1 and 2).

ns denote P< 0.5, < 0.01, < 0.001, and> 0.05, respectively.

Storage (mo.)

3 4 5

0 1 01 2 04 5 68 13 197 13 17

***... *** ***

5 6 1224 37 4455 63 72

48 63 6750 59 67

*** ***

*** .*. *..74 79 7881 75 7961 63 340 0 0

0 0*** ***

*** ...

2

1 20 22 41 63 3.. ns

Temp SMC

4.25.16.17.3l

Evaluations were based on monthly labo­ratory germination and seedling emergence(greenhouse) tests conducted in tandem dur­ing 6 mo of storage. Before testing, TPS weremoistened to a uniform SMC of 13% by plac­ing them in a sealed environment above wa­ter at 22°C for 24 h. Germination tests con­sisted of four repl ications of 100 seeds eachplaced evenly over dry filter paper in 9-cmPetri dishes. TPS were hydrated with 5 ml ofdeionized water before placing the dishes inan incubator. Temperature in the germination

Table 1. Effects of increasing storage temperature, seed moisture content (SMC), and time in storage on per­centage of germination at 2rc.

(L) andquadrati((Q)fegr~s$ion;', H ***, and ns denate P<: 0.5, < 0.01, < O.OOl, and> 0.05, respectively.

Seedling tests consisted of 5 replicationsof 20 seeds each sown in a steam-sterilizedsoil mixture of equal parts moss and sand.Emergence was checked daily and countedat first sight of the hypocotyl hook during thefirst 17 DAS, but only the percentage of emer­gence at lad is presented for simpl icity ofdata interpretation (Table 3). Temperature inthe greenhouse was monitored with ahygrothermograph and average maximumand minimum daily temperatures were re­corded (Table 3).

The experimental design was a completerandomized factorial arrangement. Data weresubjected to linear and quadratic regressionanalysis with SMC as the independent vari­able for each evaluation, and with time in stor­age for each SMC. General correlation coef­ficients of germination and seedling emer­gence were also analyzed (Table 4).

Results and Discussion

This study showed that TPS lots that germi­nate only at 17°C are dormant and should not

DP Program Report 1995·96 223

**

**

Q

ns

ns

ns

ns

**

ns

ns

38/25°C,

6

***

***

***

5078847878

23

374054

5

were 32/20°C, 34/21

6776

1763

***

Storage (mo.)

33

*** ***

ns

p < 0.5, < 0.01, < 0.001, and

nation results at 27 and 17°( might be usedas a practical criterion for estimating presentand future sowing value of TPS. The lowpercentage of germination at 27°C followedby high germination at 17°C can be explainedas evidence of dormancy. Seed deteriorationcan be assumed when seeds do not germi­nate at either temperature.

***

86

49

14

4.2

(%)

4.2

SMCTemp

30

Table 3. Effects of increasing storage temperature, seed moisture content (SMC), and time in storage onpercentage of emergence under variable temperature conditions'.

be used for sowing a crop of potatoes underfield conditions (Tables 1, 2, and 3). The re­sults also demonstrated that a high tempera­ture level close to the maximum allowablefor germination can be used as a measure ofdegree of dormancy. Germination at 27°Caccurately predicted relative seedling emer­gence ofTPS from soil under various tempera­ture conditions. The combination of germi-

224 Program 5

(IP Program Report 1995-96 225

Consequently, we prefer to after-ripenfreshly harvested TPS at 30°C and 4.5% SMC,even if longer periods of storage are required;40°C is used only when dormant TPS are ur-

Storing freshly harvested TPS at high tem­perature and low moisture until sufficientseeds have lost dormancy, as determined bygermination at 27°C, however, should onlybe considered a compromise solution forovercoming TPS dormancy. For example, theresults of this study suggest that the safest andmost effective treatment for rapidly decreas­ing TPS dormancy could be 2 mo storage at45°C and 4.2% SMC, even though only 75%of the progeny was apparently nondormantat this time, according to germination at 27°C(Table 1). Protein and lipid alterations resultfrom heat injury to biological organisms;therefore, further storage at 45°C wou Id bedetrimental to seed quality. Dormant seedsare protected from heat injury, but high tem­perature will unavoidably damage less dor­mant seeds of a given TPS progeny while themore dormant seeds are still losing their dor­mancy.

of noncultivated grasses and fruit trees in thefamily Rosaceae, and buds and bulbs of un­derground perennials. These "wild" seeds arecharacterized by a gradual widening of theallowable temperature for germination dur­ing dormancy loss in storage.

TPS dormancy was effectively releasedwith progressive increases in storage tempera­ture, SMC, and time in storage. TPS dor­mancy was more strongly preserved at 3.4%SMC at all temperatures. At ~ 5.1 % SMC ger­mination was suboptimal or decreased withinthe first month of storage at 45°C. The resultsindicated that the critical moisture point(CMP) above which seed deterioration in stor­age proceeds at a logarithmic rate is about5% SMC for TPS. This limit varies within or­thodox species (i.e., seeds resistant to desic­cation) from 2% in Arachis hypogaea to 6.2%in Pisum sativum. It is safe to recommend thatTPS should always be stored below 5% SMC.

Drying much beyond the CMP is believedto serve no additional purpose for preservingseed quality in storage. Overdrying TPS, how­ever, should be avoided because germinationand seedling emergence were increasinglyinhibited as SMC decreased below the pro­posed 5% CMP lower limit. Since this inhibi­tion was also more evident as storage tem­perature decreased, it might be a conse­quence of enhanced TPS dormancy, whichis best preserved under low temperature andlow moisture.

The nature of TPS dormancy was shownto be similar to that of many other species inwhich the true seeds have not been domesti­cated for sexual propagation, such as seeds

Table 4. General correlations for each evaluation among the various germination and seedling criteria tested.

gently needed for planting. Germination testsat 27°C are regularly conducted and whengermination after 8 d at 27°C has increasedto >50%, then seeds are stored at lower tem­peratures (1 0-20°e). If partially dormant TPSneed to be used immediately, sowing ratesmust be increased accordingly. Otherwise,continued storage at 10-20°C is recom­mended until most seeds become nondor­mant.

Conclusions

This study showed that TPS that germinateonly at 17°C should be considered dormantand inappropriate for sowing a potato crop.The percentage of germination after 8 d at27°C, on the other hand, was shown to be anaccurate criterion for estimating potentialsowing value of TPS. When this measure isused in conjunction with germination at 17°C,relative dormancy levels can also be esti­mated.

The evidence presented also suggests thatTPS should always be stored at below 5%SMC to preserve seed viability, regardless ofstorage temperature. Much lower SMC val­ues inhibited germination, and higher valuesincreased the rate of seed deterioration.

Th is work also clearly demonstrated thata period of dry after-ripening in storage at high

226 ProgramS

temperature might be used to accelerate therate of TPS dormancy loss. Th is strategy, how­ever, should be used with caution becauseseeds will begin to deteriorate after losing dor­mancy under high storage temperature.Therefore, breeders should seek a geneticsolution to the dormancy problem so that TPScan realize its full potential as an alternativemethod for propagati ng potatoes.

Selected Reading

Karssen, CM. 1982. Seasonal patterns ofdormancy in weeds. In: The physiologyand biochemistry of seed developmentand fermentation. A.A. Khan (ed.).Elsevier Biomedical Press, New York.p.243-298.

Pallais, N. 1995. High temperature and lowmoisture reduce the storage requirementof freshly harvested true potato seeds.j. Am. Soc. Hort. Sci. 120:699-702.

Pallais, N., N. Fong, R. Garcia, and j.Santos-Rojas. 1990. Factors affectingseedling vigor in potatoes. II. Genotype,after-ripening and pre-sowing treatments.Am. Potatoj. 67:109-119.

Roos, E.E. 1980. Physiological, biochemi­cal, and genetic changes in seed qualityduring storage. HortScience 15:19-22.

E. Carrasco\ A. Devaux 2, W. Garcia\ and R. Esprella1

Frost-Tolerant Potato Varietiesfor the Andean Highlands

Introduction, evaluation, and selectionof genetic materialSince 1989, about 500 clones introduced

from CIP and ICA were tested in areaswhere frosts are frequent during the growingseason. These areas are located at around3,500 m, where the average temperatureis around goC (the average minimum 1°C,and maximum 1SoC) and the yearly pre­cipitation is 500 mm. Evaluations of thefollowing factors were carried out duringseven successive growing seasons:

CIP Program Report 1995-96 227

• Percentage of foliage damage caused byfrost, and capacity of recuperation afterfrost damage.

• Agronomic characteristics of plant andtubers.

• Tuber yield and culinary quality.

tives of PROINPA's research program is tomake potato production systems in the high­lands more sustainable by developing andadapting technologies that respond to farm­ers' main constraints. As part of this work,PROINPA began developing frost-tolerant po­tatoes, building on breeding and selectionwork.

New cultivars were obtained using two strat­egies: (1) the introduction of genetic materialfrom CIP and the Colombian Agricultural In­stitute (ICA) for evaluation and selection, and(2) the generation of new clones by crossesbetween native Bolivian cultivars, introducedcultivars, and wild potato species. The clonalevaluation of the material was also carriedout on-farm, thus involving farmers' familiesin the selection of the best-performing clones.

Materials and Methods

PROINPA, the Bolivian National PotatoResearch Program, was established under anagreement between the Bolivian Ministry ofAgriculture, CIP, and Swiss DevelopmentCooperation (SOC). One of the main objec-

Frost affects production in three ways: (1)frost itself reduces production from 10% to70% for nontolerant varieties; (2) the threatof frost results in extensive, low-input man­agement practices because farmers do notwant to invest in risky operations; (3) farmersin the most affected areas reduce frost risk byusing frost-tolerant bitter potatoes selectedover centuries from natural hybrids betweenwild and cultivated species. Because of theirhigh glycoalkaloid levels, the tubers of thesebitter varieties need to be processed beforethey can be used for consumption.

1 Bolivian National Potato Research Program (PROINPA).2 CIP and the Bolivian National Potato Research Program

WROINPA), Cochabamba, Bolivia.

Nonbitter potato varieties currently grownby farmers are susceptible to frost or, in thecase of some native ones, tolerant to 0 to-1°C. It is estimated that if the level of frosttolerance of selected nonbitter potatoes couldbe maintained at -3 to -4°C for as little as 2h, yields could be increased by as much as20% to 30%.

Sensitivity to cold stress is one of the majorconstraints to potato production in the Andes.It is estimated that around 400,000 ha, rep­resenting 70% of the area under potato culti­vation in the Andean highlands of SouthAmerica, are affected by frost. In Bolivia, mostof the 140,000 ha planted to potato are above3,000 m, where frost is one of the major con­straints to production.

48483660

24244824242424

Chromosomes (no.)

Diploid

ploid

Diploid

Diploid

Tetraploid

Diploid

Diploid

Tetraploid

Ploidy

For evaluations in the growth chamber, atemperature curve of a frosty night was simu­lated with minimum temperatures of -soc. Inthe field, plants were exposed to natural frosts.Temperatures were recorded with athermohygrograph or with a maximum-mini­mum thermometer located in the field at plantlevel.

Participatory evaluation with farmersFrost tolerance alone will not ensure the

acceptance of new varieties. Other charac­teristics such as tuber shape and color, andculinary properties, must also be acceptableto farmers, market intermediaries, and con­sumers.

peratures of 1S to 20°C. The critical point usu­ally occurs between 0400 and 0630 h, whenthe temperature falls below O°c.

During the last three cropping seasons(1993-96), farmers have evaluated the mostadvanced material in on-farm trials. One ofthe techniques used was matrix scoring. Af­ter harvest the new cultivars were placed inpiles at the end of each row where they hadbeen grown. A group offarmers carefully ex­amined the new cultivars. They identified themost important criteria they looked for inadopting new varieties (yield, size of tubers,and level of insect infestation). Taking one

• Resistance to other stresses such asnematodes (Nacobbus aberrans) andwart (Synchytrium endobioticum).

Generation of new clonesWe initiated crosses between cultivated

and wild species in 1990. Table 1 presentsthe material used in this breeding program.

Frost dataIn the Andean highlands, frosts occur only

at night, always after sunny days with tem-

The F, hybrid population obtained fromthese crosses was exposed to frost; the mostvigorous and frost-tolerant clones were se­lected. Many F, lines generally show resis­tance, but their yield is low and their cook­ing quality is poor. However, one or morebackcrosses to cultivated varieties were madeto improve yield and tuber organoleptic qual­ity. The material obtained from these back­crosses was evaluated in the growth cham­ber to eliminate the susceptible clones. Se­lected clones were field-tested following thesame clonal evaluation process.

The material was tested in comparisonwith cultivated varieties, including a suscep­tible one (Solanum tuberosum), a tolerant one(5. andigena), and a resistant bitter variety (5.juzepczukil).

Table 1. Some potato species used by PROINPA for frost tolerance.

228 Program 5

CIP Program Report 1995-96 229

During the 1993-94 growing season, threefrosts occurred with temperatures from -2 to-5°C for 2 h. During the 1994-95 growingseason, only one frost (-3°C for 2 h) and ahailstorm were registered. During the 1995­96 growing season, two frosts of -2°C for 2 h,a 2-mo drought at the start of the growingseason, and one hailstorm during themidgrowth period occurred.

years. One came from CIP (389349.1), theothers from PROINPA. Figures 1 and 2 presentthe difference in yields and frost damage be­tween potential varieties and control cultivarsfor field evaluations from 1993 to 1996. Thesedata show a high phenotype stability of theclones compared with control varieties. Thereis some variability between years, however,due to genotype-environment interactionconsidering frequency and severity of frost,development stage of the crop when affectedby frost, irregular precipitation, and the ef­fects of hai I and drought.

The yield and frost tolerance of the fourselected clones were stable during the 5 yr ofevaluation and were consistently better thanthose of the control (Figure 3). From fieldobservations, it appears that the four clonescan tolerate frost of -3°C for 2 h and of -4°C

94-95 • 95-96

c.v.; 33.5% c.v.; 37.8% c.v.; 35.8%LSD .05; 0.44 LSD .05 ; 0.54 LSD .05 ; 0.48

70

60

50

40 +-------IIIIII----------rcr------,n-----­

30 +-----0---II1II1---11---1 1-11_-

20 +-171--­

10

o

Frost damage to foliage (%)

80 r;:======================::;-----iiiI

Four potential varieties were selected fromthe material evaluated during the last seven

90-123-22 90-101-3 90-123-18 389349.1 S.lmilia Luk'y Alpha

PROINPA PROINPA PROINPA CIP andigena juzepczukii tuberosum

Clones/varieties

Results

Figure 1. Foliage damage caused by frost in selected clones and control varieties in three growing seasons, from1993 to 1996.

Nutritional and culinary evaluationNutritional analysis of the selected mate­

rial was carried out in collaboration with theFood and Natural Products Laboratory of SanSimon University in Cochabamba, Bolivia.Fresh tubers stored for a month were used forthese analyses. To determine culinary char­acteristics, the potatoes were evaluated asfried and boiled. In both cases, a tasting panelof six people assessed the clones. The crite­ria used for fried potatoes were internal andexternal color, internal and external texture,taste, and general appearance. The maximumscore of these criteria was 100. For boi ledpotatoes, the criteria were consistency,flouriness, moistness, color, taste, and fleshdiscoloration, with an evaluation score of verygood, good, average, and bad.

criterion at a time, farmers placed a numberof grains of maize by each pile of potatoes toindicate how they had scored each one. Thepotatoes were then boiled and farmers evalu­ated culinary characteristics using the samemethod.

Yield (kg/plant)

20

50

40

60

30

cv= 27.8%LSD .05 = 0.30

CV =23.6%LSD .05 = 0.33

CV = 29.4%LSD .05 = 0.27

Yield

Damagedfoliage

Damaged foliage (%)70

1993-94

•

1994-95

.1995-96

There is sti II a need to test the selectedclones on a larger scale in different produc­tion areas to confirm their market acceptance.For that reason, these clones have al readybeen named (Figure 3) and have been in­cluded in PROINPA's seed production pro-­gram to initiate the process of clean seed pro-

Cultivar

ITotoreiia Condor! S. Imilla Luk'y Alpha90-123-18 CIP 389349.1 andigena juzepczukii tuberosum

Tunari90-101-3

Illimani90-123-22

5

o

30

25

35

20

10

Yield (tlha)40

15

1.6,------------------------,

1.4 +-------------1!!1a­

1.2 +-------------1!!1a­

1.0 +--IIMI----1 4--------IWI-----IOO-­

0.8

0.6

0.4

0.2

o90-123-22 90-101-3 90-123-18 389349.1 S.lmilia Luk'y AlphaPROINPA PROINPA PROINPA CIP andigena juzepczukii tuberosum

Clones/varieties

Figure 2. Yield of frost-tolerant selected clones and control varieties in three growing seasons from 1993 to 1996.

Figure 3. Yield and frost damage to foliage in potential and control varities. Average of five growing seasons,from 1993 to 1996.

somewhat less. Moreover, they have alsoshown a good capacity for recuperation andregrowth after frost.

Some of the frost-tolerant clones, such as389349.1 and 90-123-22, scored as high asor higher than control varieties in agronomicand culinary qualities.

230 ProgromS

S

R

S

VG

Drought

60.060.0

58.5

TTT

Protein

TS

S

S

Nematode

20.020.316.0

Storch

It appears that ecological and cI imaticconditions, genetic variability, and pollen fer­ti Iity of the species and cultivars in the Andes,

PROINPA's experience in Andean conditionsindicates that the use of wild species withcultivated potatoes in a breeding program isnot as complex as is often argued. In manycases, only one or two backcrosses to culti­vated species are required to obtain potatoeswith acceptable agronomic characteristics.

Conclusions

MRR

MRMRS

SS

Wart

24.0

26.0

Dry matter

fried potatoes (scole:1DO), CQCP = culinary quality in cooked potatoes,

late (130-160 days)

late (130-160 days)

Very late (l60-180 days)

Early {120 days)

(IP Progrom Report 1995-96 231

Besides the quality evaluation at thefarmer's level, the four potential varieties werealso tested for nutritional and culinary char­acteristics in comparison with one of the mostpopular varieties in Bolivia, Waych'a (Table 3).

Table 2 shows reactions of the selectedvarieties to biotic and abiotic stresses, andthe earliness evaluation.

duction. Prebasic seed of these varietiesshould be available in 1998.

Table 2. Earliness and reactions' of selected clones to some biotic and abiotic stresses, CIP-PROINPA, 1994-1996.

Table 3. Nutritional analysis and culinary tests of potential frost-tolerant varieties, CIP-PROINPA, 1996.

especially in Bolivia, give these potatoes moreflexibility for genetic manipulation than po­tatoes in other regions, since potato fertilityand reproduction are very sensitive to envi­ronmental changes.

The yield capacity of the material testedwas not directly related to percentage of fo­liage damaged by frost. Some varieties showgood frost tolerance in their foliage but donot yield well, for example, the bitter varietyused as a control. The capacity of the plantto recuperate after a frost is an important fac­tor in frost tolerance and is an important se­lection criterion. There is, however, a needto better understand the relationship betweendifferent levels of frost intensity and yield toestimate the potential impact of frost-tolerantvarieties under different frost conditions ofBolivian highlands. Research on modeling theresponse of potato to frost intensity will becarried out in collaboration with CIP andCONDESAN.

Although these potential varieties havebeen selected through participatory researchwith farmers, there is sti II the important testof market acceptance. The strategy will be tohave the varieties evaluated in different ar­eas of the country with farmers' communi­ties, development projects, and seed produc-

232 Progrom 5

tion institutions involving local traders. In thefuture, we plan to involve, earlier in the se­lection process, these other potential users ofnew varieties.

The two strategies followed by PROINPA'sbreeding program have led to the selectionof potential frost-tolerant varieties with a highpotential impact in the Bolivian highlandswhere frost is a major constraint to produc­tion. Some of these varieties could also be ofinterest in other countries where frost is aproblem. The regional networks and the cata­lytic role played by OP in the interaction be­tween national agricultural research systemsof different countries should contribute to andensure the exchange of varieties and tech­nologies of common interest.

Selected Reading

Estrada, N. 1982. Breeding wild andprimitive potato species to obtainfrost-resistant cultivated varieties.In: Plant cold hardiness and freezingstress. P.H. Li and A. Sakai (eds.).Academic Press Inc. p. 615-633.

Estrada, N., W. Garcia, J. Gabriel, and E.Carrasco. 1993. Breeding potatoes fortolerance to frost and resistance to lateblight. Am. Potato J. 70:809. (Abstr.)

E.E. Careyl, S.T. Gichuki\ O. Hidalgo2, and D.P. Zhang2

Sweetpotato Seed Units for theDissemination of Planting Materialsof Improved Varieties

(IP Program Report 1995-96 233

The basic objective of the CIP sweetpotatoseed unit is to conduct research and devel­opment activities to assist with the dissemi­nation of superior varieties, and to improvethe effectiveness of sweetpotato seed systems,so that farmers in developing countries willhave a better availability of high-quality plant­ing materials of superior varieties. To date,seed unit activities have primarily concen­trated on Peru and Kenya. In Peru, efforts havebeen made to multiply and distribute substan­tial quantities of high-quality planting mate­rials of recently released or promising variet­ies, and to identify varieties with a high ca­pacity to produce cuttings from sprouted stor­age roots. In Kenya, efforts have concentratedon the international distribution of promisingvarieties for national testing and dissemina­tion. Resu Its of these efforts are reported here.This report also discusses areas of possiblefuture emphasis for the seed unit.

Multiplication of Planting Materials

Research Objectives

In Peru, pathogen-tested in vitro cultures wereused as the starting material for multiplica­tion of planting materials of selected supe­rior varieties for distribution to various sitesin 1995 and 1996. Multiplications were car­ried out using 2-node cuttings in beds, at adensity of 100 plants per square meter. Table1 shows the quantities of planting materialsproduced by variety. Apical cuttings of se­lected varieties harvested from the multipli­cation beds were distributed to various loca­tions to serve as nuclear stocks for subsequentmultiplication and distribution to farmers.Varying numbers of varieties were distributed

The lack of early maturing, high-yieldingvarieties acceptable to farmers and the lackoftimely availability of planting materials aretwo important constraints to increasedsweetpotato production in most places wheresweetpotato has received Iittle attention fromresearchers. The problems of timely availabil­ity of planting materials are particularly se­vere in drier upland areas, where resource­poor farmers usually do not have access toirrigation and may have to wait for remnantsof previous crops to resprout at the beginningof the rains, or for small multipi ication plotsto produce adequate quantities of materialsfor planting. By the time planting materialsare available, the rains may be tapering off,thus limiting sweetpotato yields. When plant­ing materials are scarce at the beginning ofthe season, farmers may accept any availableones, thus contributing to varietal mixtures,but not necessarily increasing the frequencyof preferred varieties.

1 CIP, Nairobi, Kenya.2 CIP, Lima, Peru.

Relatively little attention has been given tosweetpotato improvement in many develop­ing countries where the crop is important. Inthese countries, research programs usuallyhave not selected improved varieties, and,even if they have, formal systems for the dis­semination of planting materials rarely exist.Instead, sweetpotato farmers in many devel­oping countries grow large numbers of vari­eties, many of which are low yielding or latematuring. These varieties are disseminatedthrough informal systems based on farmer­to-farmer exchange.

Table 1. Quantities of planting materials of selected sweetpotato varieties multiplied and distributed to Peruvianproduction zones by the seed unit in Peru.

1995 second season

14,7503,550

10,2504,0502,0502,050

13,650

11,05011,25016,750

5,25011,250

7,050

7,050

4,750

4,75010,750

9,250

149,500

1996 first season

In Kenya, seed unit activities are mainly con­ducted under the auspices of the KARl Plant

Seed Unit Activities

the number of sprouts per plot was counted.Nine roots of each done were planted perplot, and the trial was laid out as a random­ized complete block design with three repli­cations. Data analysis was done using theProc Anova procedure of SAS, and meanseparation was done using the Waller group­ing method. Table 2 presents results of thetrial. Significant cultivar variation was foundfor sprouting ability. In addition, those clonesthat produced the highest number of sproutssprouted the earl iest. The two clones with thebest sprouting ability were selected for inclu­sion in crossing blocks as parental clones.

98,240

4,930

11,4305,4303,2303,430

1,43020,63019,30014,43014,000

Name (UP number)

Total

Nacional (187003.1)Castanero (187016.2)Solyboro (187017.1)Yorado (187018.1)Tacna (187019.1)Atacama (187020.1)Canetano-INIA (188006.1)Jonathan (420014)Helena (420068)Jewel (440031)

YM89.232 (189008.5)YM89.052 (189013.2)Umana Morado (420096)Trujillano (420097)

Tanzania (440166)No. 29 (440168)

DlP 3548

CC 89.213

to each location, depending on local adapta­tion and demand for varieties under multipli­cation. During the first season, planting ma­terials were distributed to 14 sweetpotato-pro­dueing zones in Peru, and during the secondseason, planting materials were distributed to15 locations.

A study was undertaken to examine differ­ences in sprouting ability among ClP-bredclones. Fourteen clones from a high dry mat­ter breeding population were used. Storageroots were placed 15 cm apart in beds onNov. 22, 1995, and the number of rootssprouted per clone was monitored weeklystarting 26 days after planting and continu­ing until29 days after planting, at which time

Sprouting Ability

234 Program 5

Table 3. Promising sweetpotato varieties distributed widely by the seed unit in Nairobi.

Table 2. Variation among sweetpotato dones for ability to produce sprouts.

aabbebedcdedef

defdefgdefgdefgefg

efgfg

g

Waller grouping

tion and testing of much larger numbers ofgenotypes at selected regional testing sites toidentify limited numbers of promising geno­types for wide distribution. Table 3 lists thenames, CIP numbers, and origins of six vari­eties that are currently being widely dissem i­nated by the seed unit in response to requests

149.3

120.3100.0

86.771.349.0

48.746.0

43.743.0

38.331.019.0

0.0

Sprouts

(no.)

Exceptional characteristics

(IP Program Report 1995-96 235

Early, high yielding, good taste, good foliage vigorEarly, high yielding, drought toleront, oronge fleshed, low drymatter contentHigh foHageyieldEarly, high yielding,foir taste, proven acceptabilitY far refugee relieffood in ZaireEarly, high yielding, gaod lasle, broad adaptation, gaad foliage vigorEarly, high yielding, braadadaptation, excellent tasle, prohoblYl1loslwidely grown vorielyin sub-Saharan Africo

Papua New GuineaUganda

Origin

PeruChina

CubaPeru

Helena (420068)Van Shu l(440024}

Name

(CIP number)

Naveto (440131)Tanzania (440166)

Cemsa 74-228 (400004)Zapallo (420027)

YM89.118SR92.130

CC89.212YM89.133USSC.SOOST87.070

SR90.307

LMB9.128YMB9.2T5SR89.519YM89J62SR90.411

SR90.323YM89.099

Clone

Quarantine Station (PQS) at Muguga. Thiswork involves the regional distribution of rela­tively small quantities of planti ng materialsof promising varieties to be tested and dis­seminated by various partners in the region.This activity is distinct from the regionalbreeding activities that involve the distribu-

Future Considerations and Challenges

(g)

either wrapped in moist paper toweling orpacked in plastic bags, following 10-d stor­age in the dark at PQS. At the end of the stor­age period, cuttings wrapped in moist papertowels weighed roughly one-fourth as muchas cuttings packed in plastic bags.

moist paper towels packed in paper bags.Although few losses of shipments were re­ported, some problems arose with desicca­tion. We have subsequently found that thiscan be greatly reduced by packing cuttingsin plastic bags. Table 4 presents a compari­son of weights of 10 2- to 3-node cuttings

Table 4. Weights of 2-node sweetpotato cuttingswrapped in moist paper towels or in plasticbags after 1 wk of storage.

There is considerable potential for furtherexpansion of sweetpotato seed unit activities,particularly with respect to finding ways ofimproving seed systems to ensure the timelyavailability of planting materials of improvedvarieties in developing countries. Particularlynoteworthy is the general lack of informationon the potential benefits of foundation seedprograms in developing countries.Sweetpotato is a crop that is well known forthe tendency of varieties to degenerate (j.e.,to lose yield potential and varietal character­istics over subsequent vegetative generations).This degeneration has been attributed to theaccumulation of deleterious mutations andpathogens. In the United States, several statesoperate foundation seed programs that pro­vide farmers with seed stocks of varietiesmaintained true to type through positive hillselection for high yield and through the elimi­nation of off-types. Recommendations havealso been developed to enable farmers tomaintain their own high-quality seed stocks.

The international distribution of plantingmaterials of sweetpotato, a vegetativelypropagated crop, requires strict adherence tophytosanitary regulations accepted by na­tional plant quarantine services. This has usu­ally been considered to require the in vitroshipment of pathogen-tested planting mate­rials. In vitro multiplication and distributionare problematic, however, as in vitro plant­lets are quite perishable, and clones are fre­quently lost during the process of shipmentand subsequent transfer of plantlets to soil.

To overcome these problems, we have be­gun to distribute clones internationally ascuttings taken from pathogen-tested motherplants maintained in the quarantinescreen house at PQS. These mother plantsoriginate from pathogen-tested in vitro plantsobtained from CIP headquarters. At PQS theyare transferred to pots and retested forsweetpotato viruses using serology and graft­ing to indicator plants. Periodic re-testingensures that pathogen-free planting materi­als are distributed. At the time of distribution,small, 2- to 3-node cuttings are taken fromthe mother plants, their leaves are removed,and they receive a fungicide treatment priorto packaging and shipping, usually by a cou­rier service.

for improved varieties by national programsand NGOs.

By expanding the production of motherplants in the screenhouse, large numbers ofpathogen-tested cuttings can be produced perclone. However, given the rapidity with wh ichsweetpotato can be multiplied under fieldconditions, there is usually little need for ship­ping anything more than nuclear stocks (suchas 20 to 40 cuttings per clone) of plantingmaterials from PQS.

With the implementation of germplasmshipments as pathogen-tested cuttings, lossesduring shipping and establishment havedropped markedly in comparison with in vitroshipments. Furthermore, improvements havebeen made in packaging of cuttings, whichshould lead to still further reductions in losses.Initial shipments of cuttings were wrapped in

236 Progrom 5

These programs have clearly demonstratedthe benefits of positive hill selection for yieldand trueness to type.

Sweetpotato foundation seed programs donot exist in most developing countries, nordo recommendations for farmers to maintaintheir planting stocks. In traditional systemswhere farmers grow a number of varieties,there is a turnover of varieties with time, withyields of older varieties often declining, andwith the introduction of new, better perform­ing varieties obtained from various sources.Farmers also usually pay close attention tothe selection of disease-free planting mate­rial, particularly in areas where virus diseasescan severely affect yields. One thing that israrely practiced in the tropics, however, evenby many researchers, is the selection of plant­ing material on the basis of per-plant perfor­mance (hill selection). This is because plant­ing materials in the tropics are usually takenas vine cuttings from existing plants; storageroots are not used as a source of seed.

Recent studies reported by ASPRAD re­searchers in Sri Lanka and Thai land haveshown the rapid benefits that hill selectioncan have in improving yields of sweetpotatoin those countries. There is a need for fur­ther verification and broad dissemination ofthe findings from these programs in otherdeveloping countries. Demonstration of thebenefits of hill selection could lead to thewidespread practice of hill selection by bothresearchers and farmers, and might lead toincreases in sweetpotato yields while halting

the commonly observed phenomena of vari­etal decline and turnover.

Another challenging area for research bythe seed unit is the search for solutions to theproblem of timely availability of plantingmaterials for farmers in drier areas. Althoughtechnological innovations may help solve theproblem, approaches developed in a com­munity-based, participatory fashion will likelybe more successful. In this area, NCO part­ners may be sought, or work aimed at stimu­lating viable community-based seed systemsmay be conducted as part of multidisciplinaryefforts to boost sweetpotato production bydiversifying forms of utilization.

Selected Reading

Dangler, J.M. (ed.). 1994. Sweetpotatofoundation programs. HortTechnology4:223-238.

De Silva, K.P.U., and H.D. Jayawickrema.1996. Selection of true-to-type varietyWaryipola-red. In: E.T. Rasco and V.dR.Amante (eds.). Selected Research Papers,July 1995-June 1996. Volume 2:Sweetpotato. ASPRAD, Manila. p. 1-3.

De Silva, K.P.U., and A. Premathilake.1996. Effect of variety and number ofgenerations of vegetative propagation onvegetative and yield traits ofsweetpotato. In: E.T. Rascc and Y.dR.Amante (eds,). Selected Research Papers,July 1995-June 1996. Volume 2:Sweetpotato. ASPRAD, Manila. p. 4-9.

CIP Progrom Report 1995-96 237

Previous Page :Blank

Gregory J. ScottI

(IP Program Report 1995-96 239

Pro

Projections. In anticipation of the WorldFood Summit in Rome in November 1996,ClP's Postharvest Management, MarketingProgram collaborated with the Basic Food­stuffs Service of FA02 on a study of the worldpotato economy. We found (1) a tremendousshift under way in the relocation of potatoproduction from developed to developingcountries, and (2) an emerging importance ofprocessing and trade in potatoes and potato

• global projections of production, use, andtrade;

• storage; and• marketing and processing.

Noteworthy results were achieved in

Potato

REPORT

1 Program Leader. CIP, Lima, Peru.2 Acronyms cited in this section can be found written out

in the section Acronyms, p. 320.

Postharvest issues are being pushed to the topof the research agenda in many countries thatproduce potatoes, sweetpotatoes, andAndean root and tuber crops (ARTe). Thedriving force to overcome postharvest con­straints and capitalize on market opportuni­ties is the growing commercialization of ag­riculture combined with urbanization, popu­lation growth, rising incomes, and increas­ing employment of women. During 1995-96,CIP's postharvest program collaborated withindustrialized- and developing-country insti­tutions to develop technologies, provide train­ing, and supply information to makepostharvest research on roots and tubers con­tribute to reducing poverty, improving nutri­tion, and providing opportunities for womenin Asia, Africa, and Latin America.

Postharvest Management,Marketing

PROGRAM

products, which could lead to a 50% increasein potato production in developing countriesby 2000. These findings portend a greaterrecognition of the importance of potatoesgenerally, and the needs of developing coun­tries specifically, in the global researchagenda.

Storage. Seasonal potato production pat­terns in India generate large fluctuations inprices paid to farmers for their crop. Withimproved rustic stores, small farmers wouldhave another option besides selling their cropat harvest when prices are usually the lowestor putting it in cold storage. OP worked withthe Central Potato Research Institute of Indiato document traditional storage practices,analyze the experience of small farmers withcold storage, and develop low-cost rusticstores. The rustic storage improvements werea technical success, but more costly. And thedemand for such stores was lower than pre­viously calculated. A ware storage manualsynthesizing the collaborative research in In­dia and experiences elsewhere is being de­veloped because storage remains high on theIist of major production constraints in Asia.

Marketing and processing. Baseline casestudies in collaboration with the CAAS inChina, CORPOICA in Colombia, andCOSUDE in Bolivia show that potato farmersare increasingly market-oriented. Policiesaimed at improved commercialization, suchas facilitating local processing and exploit­ing export opportunities, merit greater atten­tion.

Processing is a growth sector in China andColombia in particular. Rapid market apprais­als of the processing sector in Kenya withKARl, in Mexico and Central America in col­laboration with PRECODEPA, in Indonesiawith UPWARD, and thesis research in Peru,with support from the University of Nymegenin the Netherlands, all point to a rapidly ex­panding market for processed products.

Imports of such products, while currentlylimited, could balloon if local supply does notexpand to meet local demand. This tendencyhas already emerged in parts of Latin America,

240 Program 6

where tariffs continue to fall so countries canadhere to GATT. Field trials in Peru to selectprocessing materials from advanced cloneswith desired agronomic traits continue to gen­erate a small number of promising cultivars.All indications are that the demand for suchmaterials is likely to increase.

Sweetpotato

Advances in sweetpotato postharvest researchhave consisted of

• macrostudies of processing potential;

• microanalysis of starch, flour, and feed;

• development of the commodity databaseand projections; and

• completion of methods materials.

Macrolevel studies. Studies of national andprovincial statistics in China, in collaborationwith CAAS, document the spread ofsweetpotato processing primarily for feed andstarch. Processing has income- and employ­ment-generating potential for small farmersin the poorer parts of the country. The poten­tial for the expanded use of sweetpotato as asubstitute for imported maize in pig feed is aheretofore overlooked way for China to avoidmassive feed imports predicted by some ob­servers.

Regional surveys conducted in Vietnamindicate an upswing in the use of sweetpotatofor animal feed and sweetpotato starch formaking noodles, with prospects for even moreexpansion. The surveys and analysis weredone by the National Institute of Agricu IturalSciences, the Post Harvest Technology Insti­tute, and the Animal Husbandry ResearchInstitute, with assistance from CIP, UPWARD,and OAT staff.

Similar research conducted by economistsat the University of the Philippines at LosBanos shows negl igible current use of, butconsiderable potential for, sweetpotato tosubstitute for imported feed and flour. Analy­sis of secondary data in Indonesia found thatcurrent processing accounts for some 25%of total production--far more than previouslybelieved. But, as in the Philippines, lower raw

material costs in the form of higher yields andhigher conversion rates are needed for pro­cessing to reach its full potential.

These macrostudies document the impor­tance of and potential for sweetpotato pro­cessing, layout a set of collaboratively forgedresearch priorities and policies, and providea common framework for the various institu­tions engaged in sweetpotato postharvest re­search.

Microanalysis. Detailed evaluations ofexisting technology focused on starch, flour,and feed in China, Kenya, Peru, and Uganda.Work with SAAS on small-scale starch pro­duction in Sichuan Province, China, was themost promising of all. It identified several ar­eas for immediate improvement. Operationalanalysis in Peru quantified the raw materialcosts and conversion rates needed to achieveprofitability at an existing starch plant. Thenecessary higher yields with more extractablestarch seem well within reach. Sweetpotatoflour appears more problematic in Peru for avariety of reasons. However, in Uganda-andto a lesser extent in Kenya-prospects arebrighter for flour. Markets are emerging in thewake of declining supplies of cassava flour.Economic analysis of farm-level use of rootsfor pig feed in China is extremely encourag­ing. Modest changes can improve the pros­pects for even more Widespread use.

In Peru, dual-purpose varieties with bal­anced production of vines for fodder and rootsfor human consumption show considerablepotential to improve the lot of small-scaledairy farmers.

Databases and projections. The pocket­sized compendium of sweetpotato statisticsfor 33 major sweetpotato-producing coun­tries, issued in 1996, aims at broadening pub­lic awareness about the potential forsweetpotato in developing countries.

Methods materials. In addition to researchresults and policy recommendations, a ma­jor effort has been made to improve local re­search capacity by preparing postharvestmethodologies appropriate to conditions inAfrica, Asia, and Latin America. Adding valueto root and tuber crops, the manual on prod­uct development, co-published with ClAT andIITA, provides operational guidelines and acommon framework for sweetpotatopostharvest researchers worldwide. Prices,products, and people, a compendium ofmethods for analyzing agricultural marketingin developing countries, prepared with sev­eraiiARC social scientists, is intended to servea similar purpose.

Andean Root and Tuber Crops

In our work on ARTC, considerable progresswas made in each of three special projects:(1) biodiversity, (2) commodity systems, and(3) starch processing. Work in the COSU DEbiodiversity project has emphasized evaluat­ing traditional postharvest practices for cropssuch as ulluco, oca, and native potatoes witha view to their eventual improvement. IDRCcommodity systems research has focused ondeveloping commercial products such asprotein-enriched snacks or new uses for tra­ditional flours. BMZ-supported postharvestwork involves documenting processing tech­niques and consumption patterns for starchesderived from ARTC, for example, from achira,and investigating the biochemical propertiesof the products.

As the consortium of CON DESAN partnersconsolidates, progress has been made in forg­ing a common conceptual framework andresearch agenda to follow up on findings todate. Closer links with PRODAR, the LatinAmerican network for small-scale agroen­terprise, and ClAT's rural agroenterprise ini­tiative have also been established.

(IP Progrom Report 1995-96 241

Table 1. Trends in food production and foreign trade in developing countries, 1961-91.

Making Sense of Agricultural Marketingin Asia, Africa, and Latin America

0.11.20.8

1.4

4.828.111.20.1

Trade (%)0

1961 1991

9,67355,1342,3402,225

Most important, increased production,population growth, and improvements in in­frastructure have meant that the sheer volumeof agricultural goods traded in domestic mar­kets has expanded enormously (Table 1).Hence, the potential rewards to society andindividuals from improvements in domesticagricultural marketing have multiplied in cor­responding fashion.

Limitations of Previous Research

Much of the literature on agricultural market­ing in developing countries can be catego­rized into one of three types: (1) compi lationsof basic principles or concepts, (2) reviews,syntheses, or concept papers, and (3) casestudies of particu lar marketing systems oragricu Itural marketing enterprises.

In publ ications such as these, the end re­sults of the application of economic analysisto the study of agricultural marketing oftenabound. But often lacking are step-by-stepexplanations of the procedures by which suchlocation-, time-, and product-specific re­search might be extrapolated to another place

Production (OOO t)

1961 1991

3,91010,997

940551

Rice

WheatMaize

Potato

CommodityCountry

PhilippinesIndia

Kenya

Colombia

a. Exports plus imports divided by production.Source: FAD, PC-Agrostat, unpublished, 1993.

G.]. Seottl

Agriculture has become more market-ori­ented in virtually all developing countriesover the past 30 years. Subsistence produc­tion has declined in relative importance inpart because technological improvementsmean that producers have more output to sell.Mushrooming urban areas-particularly insub-Saharan Africa-mean that more andmore consumers depend on agricultural mar­keting for their daily food requirements. Evenenvironmentalists have shown a growing in­terest in the benefits and costs associated withagricultural marketing.

1 CIP. Lima. Peru.

Recent trends in domestic, as opposed to for­eign, agricultural marketing are the focus ofa 1995 book, Prices, products, and people:Analyzing agricultural markets in developingcountries. This collection of papers by socialscientists at various international agriculturalresearch centers and their collaborators innational research systems covers both datacollection and data analysis methods.

Marketing and Economic Development

242 Program 6

or another commodity. It is this gap betweenthe conceptual and case study literature ondomestic agricultural marketing in develop­ing countries that Prices, products, and peopleattempts to breach.

Because of the frequent need for promptattention to particular policy-related market­ing issues, this publication emphasizes prac­tical and rapid research procedures. Alsoincluded are simplified substitutes for morecomplicated approaches. In setting out a col­lection of methods to help practitioners ad­dress the types of marketing questions thatanalysts are most frequently confronted within developing countries, the volume also aimsat providing researchers with a cross sectionof techniques most appropriate for the task athand.

Many contributions have appendices thatspell out guidelines on survey procedures oranalytical techniques in greater detai I. Nearlyall chapters provide examples of the applica­tion of these techniques to specific commodi­ties based on research in different develop-

ing countries. The intent here is to enrich thegeneral exposition of a series of methods withan array of commodity-specific experiencesinvolving their use.

Selected Reading

Fleming, E.M. 1990. Proposal for a market­ing systems research approach in agricul­tural development planning. Agric. Sys­tems 32:97-111.

Kinsey, J. 1988. Marketing in developingcountries. Macmillan Education Limited,London.

Scott, G. (ed.). 1995. Prices, products, andpeople: Analyzing agricultural markets indeveloping countries. Lynne Rienner Pub­lishers, Boulder, Colorado, USA.

Sellen, D., W. Howard, and E. Goddard.1993. Production to consumption systemsresearch: A review of methods and ap­proaches. Report prepared for the Interna­tional Development Research Centre, De­partment of Agricultural Economics andBusiness, University of Guelph, Guelph,Canada.

(IP Progrom Report 1995-96 243

Perceptions Versus Projectionsfor Potatoes: New Estimates Point to aChanging Global Research Agenda

G.]. Scott1 and A. Coccia2

In preparation for the World Food Summit inRome in late 1996, FAO carried out a seriesof studies to provide an overview of pasttrends and future outlook for the world's ma­jor agricultural commodities. ClP and FAOstaff jointly prepared the study (begun in 1994and written up in 1995) on potatoes---the firstof its kind for FAO for this commodity. Thispaper summarizes the principal findings fromthat collaborative effort, including the analy­sis of past trends in production, area planted,and yields; the evolution of marketing anduse patterns; and projections to the year200D-what those trends predicted and howthey compare with actual output in recentyears.

These findings served as the catalyst forinitiating a collaborative effort with econo­mists from the International Food Policy Re­search Institute (IFPRI) to generate projectionsfor potatoes, sweetpotatoes, and cassava inthe year 2020. Preliminary results from thatwork are also included here to lend greaterweight to the data presented.

Materials and Methods

We analyzed historical growth rates in pro­duction, area, and yield by region and bycountry for the period 1961-93. Point-in-timecomparisons for consumption, use, and tradefor 1961-63 vs. 1991-92 were similarly ana­lyzed.

The statistics are all from FAO databaseswith the exception of use data for the UnitedStates from the U.S. Department of Agricul­ture. The latest FAO figures on these variables

1 CJP, Lima, Peru.2 FAG, Rome, Italy.

244 Program 6

are cited selectively to substantiate the analy­sis when necessary.

The FAO/CiP projections are for a singlecommodity and for individual countries inmajor economic and geographical regionssuch as Europe, the area of the former USSR,Africa, Asia, and Latin America and the Car­ibbean. The base period is 1987-89 and theprojections go to the year 2000. On the de­mand side, the model is basically driven bychanges in population and per capita incomesinasmuch as relative prices are assumed toremain constant throughout the period (1987­89 to 2000). The results cover two iterations:(1) the base period to 2000, and (2) incorpo­rating the effects of the Uruguay Round of theGeneral Agreement on Tariffs and Trade(GATT) for the same time frame.

Preliminary results from the IFPRI/CIP col­laboration are only for potatoes. But thoseprojections for the year 2020 are made usinga model that simultaneously estimates sup­ply, demand, and trade for all the major foodcommodities. The model also explicitly al­lows for changes in relative prices and gen­erates results for selected countries, subre­gions (e.g., East Africa), and regions.

Results and Discussion

Misperception 1. As developing countriesgrow economically, potato production andconsumption will follow the pattern of sharpdecline in Europe.

Recent reports on potatoes in Europe arereplete with statistics on declines in areaplanted and production. Data on use alsoshow sharp drops in per capita consumption

(IP Program Report 1995-96 245

1201008060

(0/0)

Misperception 2. The bulkiness and per­ishability of potatoes severely limit interna­tional trade.

oped in 1994 called for potato output in de­veloping countries to reach 105.4 million tin 2000. By 1994-96, FAO production figuresshowed output at nearly 100 million t, wellon target to reach the projected total. Further­more, preliminary estimates from the IFPRI/ClP projections indicate that potato produc­tion in developing countries will continue toexpand at an average annual rate of 2.0%over the next 25 yr.

Nevertheless, trade in table potatoes andseed rose from 3 million t in 1961-63 to 7.5million t in 1991-93. If trade in processedpotato products is added, recent estimates put

In economists' jargon, potatoes are thearchetypical "nontradable," that is, the goodthat is classified as one for which only an in­ternal (or domestic) market exists. Reasons forthis classification abound. Potatoes indeed arebulky and perishable, and therefore difficultto transport over considerable distances. Theirlow unit value-to-weight ratio and corre­sponding transport costs also discouragetrade. Local (consumer) preferences for skincolor, flesh color, and tuber size, as well asfor packaging and grading, constitute addi­tional constraints to international commerce.

4020o

Coarse grains

Figure 1. Percentage increase in area of selected food crops in developing countries: 1961-63 and 1994-96averages.

Cassava

Potato

From a base period figure of 75.6 million tin 1987-89, the FAO/CIP projections devel-

Roots and tubers

Production increases were second only tothose of wheat (Figure 2). Production in­creases have been particularly strong in Asia.The annual growth rate in production aver­aged 4.0% over the past 30 yr as area plantedexpanded 2.6% yearly and yields increasedby 1.4% annually.

Wheat

Pulses

Potato production in developing countriesrose from 29 to 85 mi II ion t between 1961­63 and 1994-96, more than offsetting the dropin production in industrialized countries.Hence, world potato output rose slightly, from265 to 275 million t, even though output inEurope dropped by more than 50 million tduring the same period. China is now theworld's largest potato producer since thebreakup of the USSR; India ranks sixth. In fact,area planted to potatoes grew faster in devel­oping countries than for any other major foodcrop over the 30-yr period studied (Figure 1).

Rice

of fresh potatoes and in the use of potatoesfor animal feed. Based on these figures, Eu­ropean observers often assume that, as theeconomies of other regions of the world ma­ture, similar patterns must already exist or wi IIcertainly prevail in the not-too-distant future.But empirical evidence indicates just the op­posite.

Figure 2. Percentage increase in production of selected food crops in developing countries: 1961-63 and1994-96 averages.

350300250200

(%)

Potatoes are produced in nearly 100 coun­tries in Asia, Africa, and Latin America, typi­cally by small-scale farmers with holdingsusually less than 5 ha. A "big" potato farmerin Bangladesh, for example, might have 2 haplanted to the crop. These growers usuallydepend on family as well as hired labor toplant and harvest. Potatoes are nearly alwaysconsumed by those farm households that pro­duce the crop. In fact, potatoes in develop­ing countries are often harvested when thebasic staples of rice, wheat, or maize are inseasonal short supply. Hence, potatoes areoften referred to as a subsistence crop.

tries, imports have risen sharply even thoughtariffs are sti II comparatively high. As thesetariffs fall in the years ahead to comply withGATT, the pressure to improve competitive­ness or be forced out of production wi II beconsiderable. The window of opportunity toeffectively address such developments is clos­ing rapidly, given that tariffs for many coun­tries are due to reach the agreed-upon mini­mums in 6 or 7 yr. That is roughly the mini­mum lead time required to fully promote de­velopment and diffusion of improvedgermplasm.

Misperception 3. Potatoes produced indeveloping countries are cultivated mainly bysubsistence farmers for on-farm consumption.

15010050o

Pulses

world potato trade at 10 million t yearly, orabout 4% of annual global production. Byway of comparison, world trade in rice isroughly 3% of annual output.

Trade patterns for potatoes have also di­versified over the past 30 yr. Exports of pota­toes by developing countries have risen from400,000 t to nearly 1.3 million t in this pe­riod. Shipments of seed and processed po­tato products from industrialized to develop­ing countries have also expanded sharply. Bythe late 1980s, for example, more than onequarter of all Dutch seed exports were to de­veloping countries in North Africa. A worldmarket for potatoes is clearly emerging, withcountries tending to specialize in differenttypes of potatoes as well as developing re­gional trading partners.

Roots and tubers

Coarse grains

Cassava

Potato

Wheat

Rice

Part of the misperception about trade is theresult of inadequate statistics. FAO includesin its trade data only trade in fresh potatoesand seed. Until governments supply betterfigures, data available to FAO will continueto underestimate international trade in pota­toes and potato products. More important,many developing and developed countrieshave only recently begun to appreciate theimplications for their potato sectors of liber­alized trade pol icies and regional trade agree­ments. In a number of Latin American coun-

246 Program 6

The bulk of potatoes produced in Asia,Latin America, and North Africa--even onsmall farms--is sold. Potato sales are an im­portant source of cash income, even in thoseparts of sub-Saharan Africa and in more iso­lated pockets in Latin America where on-farmconsumption prevails. Commercial potatoproduction dominates in developing countriesbecause yields-particularly in Asia-arehigh enough for farm families to be able toeat some of what they harvest and still sellmost of the crop. Returns for potato, a cropwith a vegetative period of 100-130 days inmany parts of the tropics and subtropics, areextremely lucrative because of strong off-farmdemand and relatively high prices.

Misperception 4. As per capita incomesrise in developing countries, per capita po­tato consumption will fall.

Per capita consumption of potatoes inWestern Europe fell by 22% between 1961­63 and 1991-93; even more in Eastern Eu­rope and the former Soviet Union. As incomesgenerally increased during the past 30 yr,European consumers have preferred to eatfine grains, fruits, and other vegetables overpotatoes. Hence, per capita consumptionshrank in Western Europe from 102.3 to 79.3kg/yr, in Eastern Europe from 117.4 to 80.3kg/yr, and in the former Soviet Union from131.8 to 78.0 kg. As incomes increaseelsewhere-it is often inferred-per capitapotato consumption will fall accordingly.

Per capita potato consumption in devel­oping countries rose by 43% during the past30 yr. It is much lower in Asia (11.7 kg), Af­rica (8.0 kg), and Latin America (20.6) thanin Europe (78-80 kg). Incomes are also lower.Potato is typically a complementary vegetableor seasonal staple in developing countriesrather than a principal source of carbohy­drates. As income goes up, consumers oftenprefer to eat more potatoes to diversify theircereal-based diets.

Detailed information on consumer expen­ditures by commodity by income group in agiven developing country is often hard to find.Such data are typically for "all roots and tu-

bers," or "all vegetables," and for "all incomegroups." Where such disaggregated statisticsare available, the results typically show thatconsumption increases with income, evenamong low-income consumers. In addition,potatoes play an important role in develop­ing-country diets as a source of vitamin C andessential amino acids like lysine that are lim­iting in rice.

Misperception 5. As the area planted tocereal staples increases in Asia, the areaplanted to less important crops Iike potatomust decrease.

Increased food production in developingcountries--particularly in Asia--overthe past30 yr is most commonly associated with theadoption of new, high-yielding varieties ofwheat and rice. This trend is particularly truein South Asia, where dwarf wheat and high­yielding rice varieties were gradually takenup by large, medium, and even small farm­ers. Thousands of ha are now under cultiva­tion with these varieties, which in large partexplains the increases in area planted andproduction (Figures 1 and 2). The spread ofthe improved wheat and rice varieties greatlyfacilitated the expansion of area planted topotatoes in several respects.

The new, high-yielding cereals have amuch shorter duration than the traditionalvarieties. Hence, the time required to grow arice crop in Bangladesh was shortened fromfive or more months to four or less. This left aperiod during the agricultural calendar whenan additional crop could be grown. Further­more, to take full advantage of the improvedvarieties, farmers need irrigation. But with themuch higher yields of the improved varie­ties, investments in irrigation were now fullyjustified and spread rapidly in the cereal­growing areas. Although there is not enoughirrigation water in the off-season(s) to growrice, there is sufficient water to grow a potatocrop. As higher yields from improved cerealsmeant higher incomes for small farmers inmany areas, the increased purchasing poweroften translated into more demand for pota­toes. That meant additional increases in po-

ClP Program Report 1995-96 247

tato production and, consequently, furthergrowth in area planted.

The most recent (1991-95) national statis­tics for area planted to potato in China showcontinued expansion in the area under po­tato cultivation. Similar trends are evidentelsewhere in Asia. Furthermore, preliminaryestimates from the IFPRI/CIP projections to theyear 2020 also indicate continued expansionin area planted in the decades ahead, albeitat a more modest rate than before.

'Conclusions

Recent analyses of past trends and future pro­jections for potato clearly indicate the crop'sincreasing importance as a world food crop.Statements that would suggest otherwise arefrequently based on misperceptions about theperformance and potential of the crop in de­veloping countries. As such, potatoes meritcloser attention by policymakers and re­searchers concerned with global food prob­lems in both developing and industrializedcountries in the years ahead.

The concentration of potato production isshifting from Europe to Asia and other partsof the developing world at an astoundingpace. In 1961, potatoes produced in devel­oping countries accounted for about 11 % ofglobal output. Potato production reachedsome 30% in the early 1990s and is projectedto be around 40% in 2020. No other majorfood crop has experienced such a shift in thelocation of production over this period (1961­93).

In addition, developing countries are in­creasingly the target of industrialized coun­tries' potato exports and, to a lesser extent,vice versa. Therefore, the needs of produc­ers and consumers in Asia, Africa, and Latin

248 Progrom 6

America increasingly will be the focus of po­tato researchers worldwide. Postharvest issuessuch as trade and processing are entering acritical phase in this regard inasmuch as tar­iff barriers are set to come down and the de­mand for processed products is certain to in­crease for many reasons.

Processing and trade are the two fastestgrowing sectors in the global potato economy.The international database for processing andtrade-particularly for developing coun­trier-needs to be improved. Otherwise, fore­casters will simply continue to underestimatetheir growing importance. Building on pastsuccesses in the collaborative work on pro­jections, th is might well be an area for futurejoint initiatives between CIP and FAa.

Selected Reading

Crosnier, J.c. 1994. L'evolution de la culturede la pomme de terre en Europe et enFrance. In: Proceedings of the 12th Trien­nial Conference of the European Associa­tion for Potato Research. Held in Paris,France, 18-23 July 1994. Institut deRecherche Agricole (INRA), Paris, France.

FAO/OP (Food and Agriculture Organizationof the United Nations/International Po­tato Center). 1995. Potatoes in the 1990s:Situation and prospects of the world po­tato economy. Rome, Italy. 39 p.

Rosegrant, M., M. Agcaoili-Sombilla, and N.Perez. 1995. Global food projections to2020: Implications for investment. Food,Agriculture, and the Environment Discus­sion Paper 5. IFPRI, Washington, D.C.,USA.

Scott, G. 1994. The emerging world marketfor potatoes and potato products.Economie et Gestion Agro-alimentaire(France) 30:19-27.

Sustainability of Potato Consumption inDeveloping Countries: The Case ofBangladesh

G.]. Scottl and H.E. Bouis2

Since the early 1960s, a number of horticu 1­tural crops have experienced very rapid in­creases in production in developing countries.Typically, they are high-value, short-duration,labor-intensive crops grown primarily for salerather than for on-farm consumption. As aresult, several countries, particularly in Asia,look increasingly to horticultural crops as asource of increased output, consumption, andincome.

Potato (Solanum tuberosum) is particularlyimportant, partly because production growthhas been so noteworthy. The percentage in­crease in production for potatoes in develop­ing countries from 1961 to 1996 was greaterthan that for any other major food crop ex­cept wheat. For example, potato productionin India increased by 525% during the pe­riod to nearly 17 million t. In Pakistan, po­tato production increased from 28,400 t in1947-48 to over 1 million t by 1994-96. Tur­key, Iran, North Korea, and Bangladesh havealso had substantial increases in potato out­put. The domestic market has absorbed vir­tually all of this increased production.

These trends have raised a series of ques­tions about the potential for expanded potatoconsumption and production.

• Has the observed increase in consumptionbeen due to changes in relative prices orchanges in income?

• To what extent would even lower prices,through increased production, stimulateeven higher demand?

1 CIP, Lima, Peru.2 International Food Policy Research Institute, Washington,

D.C., USA.

We attempt to answer these questions byexamining historical demand elasticity esti­mates for potatoes in the case of Bangladeshand then comparing them with observedtrends in use.

Materials and Methods

Results presented in this paper draw uponthree different methods and sets of data. Be­cause of space lim itations, on Iy the resu Itsthemselves and their interpretation are in­cluded here. The first method involves esti­mating the demand parameters for a numberof key food groups based on household ex­penditure data and a simplified analyticaltechnique designed especially to estimate ademand matrix for a highly disaggregatedgroup of foods.

The second method consists of a more tra­ditional procedure used to estimate the sameparameters, but with household expendituredata collected some 15 yr later.

The third method includes the results of arapid market appraisal and descriptive analy­sis of the latest secondary data on produc­tion and consumption gathered in field workand statistical monitoring since 1982. Thecross-checking of results is intended to testthe predictability of the estimated parametersas well as the rei iabi Iity of such estimates forpredicting longer-term trends in consumerbehavior.

Results and Discussion

Baseline historical data for Bangladesh aretaken from the Household Expenditure Sur-

ClP Program Report 1995-96 249

2.242.462.56

2.75

1.001.011.04

1.06

1.631.761.771.98

Morket price

(US$}

Potato Wheat Rice

2.182.392.492.67

1.43 2.28 1.46 1.43 2.341.50 2.36 1.41 1.50 2.431.46 2.41 1.64 1.46 2.48

lJ5 1,64 2.74

Historical information about food importsand real wages helps to put these figures inperspective. In 1973-74, Bangladesh had justrecently achieved nationhood after a war ofindependence. The devastation of the warwas aggravated by the famine of 1974.Hence, in 1973-74 Bangladesh was heavi Iydependent on food aid and commercial ce­real imports.

Per capita annual potato consumption inBangladesh in 1973-74 was higher in urbanareas than in rural areas (Table 1). More than85% of the total population resided in ruralareas at the time. Still, in urban areas, pota­toes were more than seven times as expen­sive a source of calories as wheat for low­income groups and nearly nine times as ex­pensive for high-income groups, which pur­chased higher quality potatoes. Also in urbanareas, potatoes were more than three timesas expensive a source of calories as rice. Theprice differential between wheat and potatoesand between rice and potatoes was not nearlyso great in rural areas.

areas; the price of rice was about the samebetween urban and rural areas.

(per 1,000 calories}

Rice

desiignoting the lowest expenditure quartile.

58.2

26.0

5.2

1.02.63.1

b. Relative

250 Program 6

Rice and wheat are the two main staplefoods consumed in Bangladesh. In calorieequivalents, rice was more than twice as ex­pensive as wheat in urban areas at the timeof the 1973-74 survey. Based on these his­torical data, apparently both urban and ruralpopulations would buy higher quality wheatand rice as incomes rose, although the ten­dency is more marked for rice. Wheat wasmore expensive in rural areas than in urban

vey for 1973-74, conducted by the Bureau ofStatistics. Selected food consumption patternsusing these data are shown for urban and ru­ral, high- and low-income consumers (Table1). Relative price data per 1,000 calories areexpressed as a ratio of the price paid for theleast expensive grain (in this case, for wheat)by the low-income, urban quartile. For ex­ample, in 1973-74, the lowest income urbanconsumer in Bangladesh paid 1.63 times theprice of wheat for 1 kg of potatoes (Table 1).However, since potatoes contain roughly one­fifth the calories of wheat on a price per calo­rie basis, potatoes were 7.39 times more ex­pensive than wheat, due partly to their higherprice, but more importantly to the lower quan­tity of calories (Table 1).

Table 1. Consumption per annum and calorie prices for potato, wheat, and rice in Bangladesh, 1973-74.

The first set of simulations assumed a 25%increase in income for each income quartile.Not unexpectedly, consumption increases arelarge given the low initial levels of potatoconsumption and the high income elastici­ties.

Simulated demand changesUsing historical demand characteristics for

potatoes in Bangladesh, we ran four sets ofsimulations to examine the effect changes inthe prices of particular foods and incomemight have on potato demand. We appliedthe consumption level in 1973-74 to the fooddemand elasticities given in Table 2 to yieldthe simulations presented in Table 3.

The second set of simulations assumed a25% increase in the prices of all foods. Thatis somewhat equivalent to a decrease in in­come (except that nonfood expenditures be­come relatively more attractive). Under thisassumption, consumption decreases precipi­tously.

groups when compared with industrializedcountries.

Own-price

The 1973-74 survey data reveal large per­centage increases in per capita consumptionof potatoes across income quartiles in bothurban and rural areas (Table 1). Consump­tion was low, however, even for high-income

-1.02-1.02

Real wages in Bangladesh were also at arelatively low point in 1973-74. Reasons citedfor this include the political unrest leadingup to independence, destruction caused bythe war for independence, and the famine of1974.

(IP Progrom Report 1995-96 251

Total wheat supply was in the neighbor­hood of 1.7 million t. According to FAO,nearly 95% was imported. Domestic wheatproduction at the time was slightly over100,000 t. Domestic potato supply consistedof some 725,000 t, virtually all of which wasproduced locally. Local wheat prices weredepressed by aid, imports, and food subsi­dies, particularly in urban areas. Hence, thelarge differences in relative prices per caloriefor potatoes vs. wheat that prevai led at thetime the household survey was carried outwere at least partly due to these unusual cir­cumstances.

Table 2. Summary of selected income, own price, and cross-price elasticity estimates for potatoes byincome quartile and urban and rural populations for Bangladesh, 1973-74.

consumption from around 5 kg per capita in1973-74 to around 16 kg per capita in1981-82.

More recent consumption patternsPatterns in 1988-89. Several factors led to

changes in potato consumption patterns inBangladesh during the remainder of the1980s. First, potato production increasedmarkedly due to increases in yield and areaplanted. Yield increased an average 2.7% an­nually from 1961 to 1993, whereas areaplanted increased at an annual rate of 1.8%.By 1993, annual potato production was 1.3million t.

Second, wheat production increases werealso impressive during the period, althoughthey have tended to level off in recent years.Wheat production was 1.08 million t in 1991­93, only slightly higher than the 1.03 milliont produced in 1981-82. Area planted to wheatgrew by about 7% in the 1980s, from 563,000to 604,000 ha. Not only did local productionof wheat increase, but imports in 1988-89were higher in absolute terms than in 1973-

1.06 -1.10 0.18 0.93

1.41 -1.51 0.25 1.321.86 -2.04 0.33 1.861.93 -2.30 0.25 2.22

-0.42 0.15 0.26-0.93 0.32 0.66-1.06 0.33 0.78-1.36 1.16

Change in per capita consumption per year

25% increase 25% increase 25% decrease in 25% decrease

in per capita in price of price of prima ry in price of

income all foods staple foods potatoes

(kg/year)

Initial

per capita

consumption

per

eJ 1.02.63.14.7

Urban­

rural/income

quartile

Urban

1 (low-income) 3.

2 5.23 7.34

Table 3. Simulated changes in demand for potatoes by income quartile and urban and rural populations forBangladesh, 1973-74.

A third set of simulations assumed a 25%decrease in the price of rice, which effectivelyincreases income. Even though rice becomesan even cheaper source of calories than po­tatoes, potato consumption increases becauseof the increased income.

The fourth simulation assumed a 25% de­cline in the price of potatoes. The increase inper capita consumption of potatoes based onthat assumption is on the order of 25%.

Actual demand changesGiven the rise in per capita consumption

of potato and its growing importance in thelean season in Bangladesh since 1973-74,potato has evolved from a minor vegetableto the most important vegetable in the dietand an occasional partial substitute for rice.That is consistent with the historical demandparameter estimates reported in the previoussection, and with an observed increase in theprice of rice relative to potatoes. The priceratio rose 45% from 1973 to 1983 in Dhaka.The decrease in the relative cost of potatoesgreatly contributed to the increase in rural

252 Program 6

Figure 1. Real wages of agricultural laborers, Bangladesh, 1949-93.

19931988

CIP Progrom Report 1995-96 253

198319781973

Potatoes are more than just an alternativesource of calories, or a tasty alternative to astrictly cereal-based diet. In Bangladesh, po­tatoes are an important source of vitamin Cand also provide essential amino acids thatare low in rice.

Patterns in 1995-96. Potato production inBangladesh rose by nearly 250,000 t between1988-89 and 1995-96 to 1.45 million t. De­tailed consumption figures by place of resi­dence and income quartile are harder tocome by. But FAG Food Balance Sheet dataindicate that average per capita consumptionin 1992-94 was 9.8 kglyr, more than doublethe 4.8 kglyr reported for 1961-63. The Inter­national Food Policy Research Institute andCIP estimate continued increases in potato

urban areas and actually rose in the country­side (Table 4). As rice consumption increased,particularly among low-income consumers,this added sense of wealth engendered in­creased potato consumption as well. In­creased potato consumption is consistent withthe rise in real wages.

Year

-. - Nominal wage/computed RePI

-x- Trend 1949-64-~- Trend 1965-80-0- Trend 1981-91

19681963

1949 =100

115

110

115

100

95

90

85

80

75

70

65

60

55

501948 1953 1958

The relative price for potatoes vs. rice,however, remained virtually unchanged in

Fourth, real income increased sharply dur­ing the 1980s (Figure 1). Among the possiblereasons are the spread of improved rice vari­eties capable of high yields in the dry sea­son.

Fifth, results from the Bangladesh house­hold expenditure survey for 1988-89 showthat per capita potato consumption rosesharply (Table 4). That appears consistent withthe shift in relative prices for potatoes vs.wheat-particularly in urban areas whererelative prices fell by 50%.

74. However, population growth inBangladesh virtually eliminated any increasesin per capita availability of wheat.

Third, total rice supplies increased by morethan 40%, from 12.9 to 18.8 million tons. Thespread of high-yielding varieties was a prin­cipal factor. Rice import increases were mi­nor compared with increases in domestic pro­duction.

Table 4. Consumption of rice, wheat, and potatoes, ond computed relative prices per 1,000 calories inBangladesh, 1973-74 vs. 1988-89.

135.320.1

3.933.16 3.19

1988-89 quartiles

High Low

196.3

17.0 25.1

essential vitamins and amino acids they pro­vide. Potatoes are sti II an expensive sourceof calories relative to wheat and rice. But aswe have shown in Bangladesh, the relativeprice vs. wheat has fallen substantially. Esti­mates for Bangladesh indicate that the pros­pects for increased potato consumption arefavorable, yet modest in per capita terms, ifincomes increase and potato prices continueto ded ine relative to staples.

Government policy can greatly influencethe future demand for potatoes. Various mea­sures might be adopted to help further lowerproduction costs and the retail price. Amongthem are lowering the cost and improving theavailability of planting material and storagefacilities, and cutting subsidies on importedwheat. Given the estimated demand param­eters, increased potato supplies could bereadily consumed in the local market.

83.2

1973-74 quortiles

Low

Conclusions

production and consumption well into thenext century.

Potatoes are of increasing interest topolicymakers and planners in developingcountries because of their proven potentialto raise farm incomes, rural employment, andfood consumption. This last consideration isparticularly important in South Asia wherelarge segments of the rural population arelow-income consumers.

To better understand past increases in po­tato consumption and to more accurately es­timate the potential for further growth, basicinformation is required on the demand char­acteristics of the commodity. In NorthAmerica and Europe, potatoes are regardedas a starchy staple. But in Asia they are val­ued for their dietary variety, taste, and the

254 Program 6

Selected Reading

Bouis, H.E. and G.J. Scott. 1996. Demand forhigh-value secondary crops in develop­ing countries: The case of potatoes inBangladesh and Pakistan. FoodConsumption and Nutrition DivisionDiscussion Paper No. 14. InternationalFood Policy Research Institute (IFPRI),Washington, D.C. 42 p.

Goletti, F. 1993. Analysis of demand forpotatoes in Bangladesh. IFPRI,Washington, D.C. 35 p. (In mimeograph.)

Scott, G. 1988. Marketing Bangladesh'spotatoes: Present patterns and futureprospects. International Potato Center((IP)/Australian Development AssistanceBureau (ADAB), Dhaka, Bangladesh.107 p.

ClP Program Report 1995-96 255

S.G. Ilangantilekel, V.S. Khatana\ ].P.Singh2, and D. Kumar

Improved Rustic Storage in South Asia

Considering FAO estimates of 17%postharvest potato losses in India, then themonetary losses for a season cou Id be ap­proximately US$55 million. Farmers who areunable to avail themselves of cold-storagespace will benefit from improved traditionalstorage methods that decrease losses and in­crease their income.

Traditional storage practices vary by dis­tricts within a state. The end use of the har­vested potato governs the storage practice. Itcould vary from domestic storage in house­holds, mainly forfami Iy consumption, to com­mercial storage in traditional structures, heapsor clumps under trees in orchards, and un­derground pit-storage structures found in thestate of Madhya Pradesh. The main force be­hind pit storage, where potatoes are kept forover 2 mo under ambient conditions, is thedemand for potatoes for processing. In hu­mid West Bengal, potatoes are stored in ordi­nary rooms, generally on raised bamboo plat­forms. Storage in Uttar Pradesh begins in latewinter and the temperature increases rapidlyfrom late February onward. The increasingtemperatures result in heavy storage losses.

Earlier studies indicated that rustic storeswith evaporative cooling to lower tempera-

Assuming that the entire existing installedcold-storage capacity for potato operated atfull efficiency, only 40% of the potatoes pro­duced in the country could be cold-stored.Because of the shortfall of cold-storage ca­pacity and low prices experienced at harvest,about 4 million t of harvested potatoes arestill traditionally stored, since this is the onlychoice left with farmers.

pacity of cold stores is 8.7 t. Estimates indi­cate that 92.5% of total cold-store space isused to store potatoes.

1 ClP, South and West Asia Regional Office, NewDelhi, India.

2 Central Potato Research Station, Modipuram, India.

A major portion of the harvested potatoesare stored in cold stores for long-term stor­age. Potato prices are lowest at the peak har­vest season, generally from early February toearly March when the major crop of potatoesis harvested in Uttar Pradesh. The usual trendin price variation results in about a 50% in­crease in prices within 2-3 mo of the peakharvesting period.

The available cold-storage capacity inmany of the potato-producing states in Indiafalls short due to the high demand experi­enced during the harvest. The installed ca-

Potato production is mainly concentratedin the northern plains comprising the statesof Uttar Pradesh, Bi har, and West Bengal.About 81 % of the total potatoes produced inthe country are harvested from January toApril and are available for market, but only28% of those potatoes are demanded as warepotatoes during the period. This creates a sur­plus of 53% of ware potatoes, which have tobe used or stored over the next 6 months fromMay to November. In addition, about 10% ofthe total potato produce harvested in the sameseason needs to be stored as seed to be usedfor the next production year.

256 Program 6

India ranks second only to China among theAsian countries in potato production. Thecountry produced 20.3 million t of potatoesfrom 1.26 million ha area during 1994-95. Ifthe trend of the 1990s continues, total pro­duction could reach 28 million t by the year2000. Thus the country should be ready tohandle an additional 8 million t of potatoeswithin 5 yr. This may be a difficult task, par­ticularly when postharvest faci lities to handleexisting potato production are limited.

tures and increase humidity provide a betterstorage atmosphere than the traditional stor­age systems. But research is limited and theeffectiveness of the storage system on-farmhas not been studied. We therefore undertookrustic-storage trials in Uttar Pradesh to testsuch storage systems in farmers' fields forware potato storage. We also conducted stor­age surveys to determine the status of tradi­tional and cold stores in potato-growing dis­tricts.

Materials and Methods

Over the past three years, CIP constructed andevaluated evaporative cooled rustic stores(EVS) in farmers' fields. The storage experi­ments were done in collaboration with theIndian Council for Agricultural Research(ICAR) in the Central Potato Research Insti­tute (CPRJ).

Sectional PlanAll dimensions are in meters

2.1:0==-__ X

Figure 1. Drawing of an evaporative cool store.

The actual experimentation was done incollaboration with scientists from the CentralPotato Research Station (CPRS), in MeerutDistrict, and in farmers' fields in Meerut,Muzaffarnagar, and Farrukhabad districts ofUttar Pradesh. Storage surveys were con­ducted in collaboration with scientists fromthe CPRI. Eighteen improved EVS were con­structed in different farmers' fields using lo­cally available material such as brick, mud,wood, and thatched roofs (Figure 1). Cementand bricks were used to build the evapora­tive chamber at the bottom of each store.Cement troughs were constructed with an ar­rangement of brick channels, to increase themovement of air under the store. Sand usedas the evaporating surface was placed in thetroughs to a depth of 6 cm between the brickchannels and was kept wet during potato stor­age. The water level was kept at about 0.5 cm

Lip ofdrain

Rofary exhaust turbine

CIP Program Report 1995-96 257

above the sand to ensure adequate moisturefor evaporation.

A locally constructed wind turbine was fit­ted to the roof of each store. The suction ofthe turbine was set to minimize desiccationof the stored potatoes. Westerly winds pre­vailed during most of the storage season, sothe stores were constructed facing the north­south direction. The easterly lip of the watertrough was higher than the westerly lip to re­strict the hot, dry air moving through thetrough to the outside. This enabled a longerresidence time for the hot, dry air inside thewater trough, thus providing better evapora­tion.

The potatoes were stored on bamboo matsplaced on the brick channels inside the store.Walls were plastered with about 3 cm of mud

and straw mixture to give better insulation.Holes (2 cm diam) were made on the sidewalls of the eastern and western side of eachstore at a height of 1.5 m to measure tem­perature inside the store using a long­stemmed thermometer. The holes were sealedwith mud between temperature readings.

Initial temperature and relative humidity(RH) data were collected at the time of fillingstores and regularly thereafter. At the CPRSstore, dial thermometers were permanentlyinstalled with the probes in direct contact withthe stored potatoes to give temperature ofpotatoes during storage. A Stevenson's screenwas fixed for ambient temperature and RHmeasurements. Continuous monitoring ofstore temperature and RH at the CPRS storewas done using a continuous-recordingThermohydrograph installed at a height of1.6 m. Observations on potato quality weretaken at 2-wk intervals by opening the storesearly in the morning when the difference be­tween the inside and outside temperature wasa minimum. Similar observations were madein farmers' fields during regular visits to moni­tor the progress of the experiment.

Potatoes for storage were sorted andweighed; damaged tubers were discarded.Stores were filled in March. The varieties

258 Program 6

stored were Kufri Bahar, Kufri Badshah, KufriChandramukhi, JI-5857, and TPS families.Potatoes were piled to a maximum height of1.5 m. The effective storage capacity of thestores was lOt, although in some instancesthe capacities were increased at farmers' re­quests and at their cost. The quantity storedranged from 2.5 t to as much as 14.6 t. Afterthe stores were loaded, their doors weresealed with mud to give better insulation.Moisture or weight loss of potato in the im­proved rustic stores as well as in the heap/ordinary room was evaluated by placing 5-91O-kg bags of potatoes in different places (bot­tom, middle, and above the stored potatoes).

Potatoes were stored under these condi­tions until farmers decided to sell, based onthe prevailing market price. Observationstaken On the day of sell ing the stored pota­toes were (1) number of sprouted tubers, (2)number and weight of rotted tubers, and (3)the final weight of good tubers. The prevail­ing price of potato in markets in close prox­imity to the stores under study was noted atthe time of both storage and sale.

Results and Discussion

Cooling efficiencyDaily and weekly temperature data taken

from the beginning of storage in March to 1June (the time of selling) indicated that therewas a uniform reduction in temperatures be­tween ambient and the inside of the store.The morning (0800 h) ambient temperatureswere not significantly different from the tem­perature inside the store (Figure 2). The out­side temperatures in the morning began torise significantly from March to the end ofMay. The difference between the temperaturefrom 0800 h to 1400 h averaged around 16°C.

Temperatures increased from about 35°Cin March to more than 40° C at the end ofMay for readings taken at 1400 h; inside theEVS the temperature recorded at 1400 h was12-19°C lower than the ambient. The turbineinfluenced uniform upward movement ofevaporating moist, cool air through the po­tato pile and reduced fluctuations in tempera-

Figure 2. Comparison of minimum and maximum inside and outside air temperatures in EVS, March to April 1996.

-+- Inside min.

-"- Inside max.

~ Ambient min.

1+- Ambient max.

0:>O"lC\l

There was a significant reduction in tem­perature and increase in humidity inside theEVS during the hot, arid months from April toJune, thus maintaining a higher quality ofstored potatoes. Weight losses in potato were

CIP Program Report 1995-96 259

In 1996, losses of the EVS in Meerut var­ied from 6% to 11 % over a storage period of43-53 d. The farmers who stored in March,when temperatures were still low, had only8% losses in an 85-d storage period. Rottedtubers varied from 0.7% to 3% and sproutedtubers varied from 5.5% to 98.7%. Maximumsprouting was noticed in the case of the farmerwho stored the longest (85 d).

Farmers in the study area without storagefacilities heaped their produce. The losses inheaps were 4.3% and 7.5% in storage peri­ods of 33 and 35 d, respectively. The 7.5%losses in heaps during 35 d was higher thana 6.9% loss in EVS during 47-d storage. Farm­ers who stored their potatoes in heaps werepaid lower prices because of the low qual ity.

r.oC\l

13.9% compared with 10.4% in EVS duringthe same period (Figure 3). The reason forshort-duration storage in some stores was thesale of potatoes by farmers when the priceswere comparatively higher than at harvest.

~«C')C\l

oC\l

Days

~«C\l

Degrees C

45

40

35

30

25

20

15

10

5

O+-t-++-t-t-t-t-t-i-t-i-HH-!""t'"t-I--t-t-.......+-+++-t-t........-t-ir-t-1H-t-t-!""t'"'I-i

During 1996, farmers of Farrukhabad suf­fered losses of 2.8-10.4%, over a storageperiod of 24-61 d. The losses in potatoesstored for 61 d in the ordinary room were

The airflow provided by the turbine re­duced the desiccation of potatoes in storage,and maintained a uniform temperature insidethe store depending on outside temperatureand humidity.

Reduction in lossesIn 1995, average total losses were 11.3%

in Muzaffarnagar and Meerut, and 20.4% inFarrukhabad. The losses were substantiallyless (10%) at the research station, which maybe because of better maintenance and man­agement of the store at the research farm. Theminimum losses of 3.5% were observed at afarm in Bopada village in Muzaffarnagar. Thisfarmer was very progressive and worked onthe construction of the EVS, and took a keeninterest in monitoring temperature and waterlevels in the trough.

ture inside the store. The temperatures insidethe store observed at 0800 hand 1400 h werenot significantly different. Therefore, earlymorning hours are the best times to inspectthe stores.

Figure 3. Comparison of storage losses for potatoes stored in EVS and those stored in heaps after 61 d, 1996.

10987

ProfitabilityProfitability of an improved technology is

the main factor that influences adoption. TheEVS technology was more profitable than thefarmers' practice of storing potatoes in housesand in heaps. In Farrukhabad, the price ofpotato was Rs 2.1/kg ($0.06/kg) when storeswere filled. It had increased to approximatelyRs 3.75/kg ($O.l1/kg) after a period of 24-61 d.The gross return was 11 % higher per kg ofpotato stored in EVS than in ordinary roomsand in heaps.

In Meerut, overall weight loss in potatoesstored in EVS varied from 6% to 11 % over astorage period of 43-85 d. The gross returnsin heaps ranged from Rs 189/t ($5.30/t) to Rs494/t ($14/t) compared with Rs 269/t ($7.62/t) to Rs 1,030/t ($29/t) for potatoes in the EVS.The highest gross return was earned by afarmer who stored for the longest period (85d) in the EVS, because he received the high­est sale price in June. But when net profitsare considered, heaping of potatoes is moreprofitable because of the high cost of con­structing EVS. Storage in heaps, however, hasa risk of high rottage due to rain. Neither canpotatoes be stored as long in heaps as in EVS.

More than 20% of the potatoes grown inthe Uttar Pradesh plains are used for seed andstored in cold stores after harvest. Uttar

5 6

Farms

This study was the first major attempt totake the technology of rustic storage to farm­ers' fields. The results indicate that potatoesstored in EVS had lower weight loss andhigher quality at sale time. An added advan­tage is that the EVS provided a convenientmeans of keeping potatoes in bad weather,whereas those stored in heaps were exposedto rain and desiccation.

Losses in the Farrukhabad stores werehigher than those in Meerut andMuzaffarnagar. There was no climatic differ­ence in these districts and the losses may beattributed mainly to leakages and poor man­agement of water in the troughs. Althoughstores were located in close proximity to tubewells, the nonavailabi lity of an assured sourceof power and the lethargy of farmers to keepthe sand surface moist resulted in lower cool­ing efficiencies.

influenced by variety, preharvest andpostharvest management practices, store con­struction, and store management.

Lower losses in 1996 at all sites comparedwith 1995 strengthens the line ofthinking thatstore management plays a key role in potatostorage. Farmers were more knowledgeableabout potato storage during the second yearof the trial and thus reduced their storagelosses.

260 Program 6

(IP Program Report 1995-96 261

early months of storage, for those who do notwant to be at the mercy of cold-store owners,and for those unable to avail themselves ofcold-store space at harvest. If the storage costof the EVS could be significantly reduced tobelow the cost of cold storage, then EVS cou Idbe justified for short-term storage. If not, UttarPradesh farmers will continue to use coldstores, which guarantee better produce qual­ity even though their availability fluctuates.Table 1 compares costs and returns for theEVS, heaps, and pits with the cost of cold stor­age.

The EVS has a definite advantage for farm­ers wanting to dispose of their potatoes in the

Table 1. Comparison of storage cost of EVS, heaps, ond pits with the cost of cold storage'.

Pradesh is traditionally a seed supplier to therest of the potato-growing areas and there­fore depends heavily on cold stores. This hasresulted in a concentration of cold stores inUttar Pradesh. Any new technology musthave significant advantages over cold stores,traditional heaps, and other structures. Thecost of EVS is sti II higher than that of the heapsor other structures, and not significantly lowerthan the cost of cold storage per kg of potato.

Rapidly increasing potato production in In­dia is placing a strong demand on the cur­rently avai labIe, limited postharvest facil ities,especially those to store ware potatoes. Bythe year 2000, the country needs to be readyto handle an additional 8 million t of pota­toes, although cold-store space is limited.

duce (Table 2). Cold-store charges in thesestates are much higher than in Uttar Pradesh.Farmers in these states may find the EVS tech­nology quite profitable for ware and for pro­cessing. These states cater to the needs ofpotato processors by storing potatoes in in­digenous structures, built with high invest­ments. The investment in EVS is significantlylower than the investment in traditional stores,which do not have the cooling and lowerweight loss advantage of the EVS.

Conclusions

Store losses in the different districts variedfrom 4% to 11 %. Loss depended mainly onthe initial condition of potatoes going intostorage and the duration of storage. Otherfactors such as store management and watercontrol in the EVS troughs also contributedto losses. Losses in heaps were lower thanexpected, but sti II higher than losses in EVSfor a similar duration.

Adoption domainsThe cooling efficiency of the EVS during

the hot, arid months from April to June gavea higher-quality potato to the market. Butfarmers have yet to understand the need foroverall management of both produce andstores during the storage period, if the tech­nology is to be successful.

The Uttar Pradesh plains are semiarid.Temperature rises to about 44°C in summerand drops to about 3-4 °C during winter. Thestates of Madhya Pradesh and Gujarat havetemperatures similar to Uttar Pradesh, but thehumidity is even lower. The scope for EVSadoption is higher in these three states thanin all the other potato-growing areas in In­dia.

produdion

Increasing interest and demand for pro­cessed potato, mainly for chips, is creating asignificantly increased demand for indig­enously stored potatoes. Large processingcompanies pay premium prices for good­quality potatoes that have not been in coldstorage in Madhya Pradesh. These potatoeshave lower sugar contents and optimum pro­cessi ng qual ity.

Table 2. Potato production and cold-storage capacity in major potato-producing states of India, 1992-93.

In Madhya Pradesh, Gujarat, andKarnataka, cold-store space falls much shortof the optimum level of 55% of the total pro-

262 Progrom6

Profits (based on prevailing prices) offarm­ers were significantly higher for those whostored their produce efficiently for 2 mo ormore.

Postharvest management of potatoes be­fore storage and the management of stores

after filling affect EVS efficiency. Proper man­agement of the total storage system providesa better qual ity of stored produce.

C1P Progrom Report 1995-96 263

Recent Advances in CIP's Strategy forCollaborative Postharvest Research onSweetpotato

G.]. Scott and C. Wheatley!

Postharvest issues are particu larly relevant tothe development of root and tuber crops.Unlike the cereals, these crops are perishable.And given their seasonal production patterns,their effective use, either as planting materialor for consumption, depends on proper pres­ervation through storage or processing. Infresh form, root and tuber crops are bulky andlow value in relation to transport costs. Theyare often produced in rural areas at consider­able distances from urban consumptioncenters-a problem particularly acute in sub­Saharan Africa.

Greater availability of sweetpotato in themarket and at reduced cost to consumers iscontingent upon improved processing or mar­keting or both.

Roots and tubers often contain either toxic(glycoalkaloids) or unattractive (flesh color)traits that can be eliminated in processing.Postharvest activities enable roots and tubersto achieve their full potential as sources offood in other than fresh form (flour, meal,starch), as raw materials for secondary pro­cessed products (modified starch, noodles,glucose, candyl, or in the form of feed (fo­Iiage, roots, by-products). In the case of rootsand tubers, the combination of traditionalknowledge and modern science offers par­ticularly good promise for impact.

This paper presents a synthesis of the strat­egy and recent advances from CIP's collabo­rative postharvest research program forsweetpotato. The section on materials andmethods summarizes the objectives and givesan overview of the four phases (Table 1) of

1 ClP, Lima, Peru, and CIP, Bogar, Indonesia, respectively.

264 Program 6

CIP's postharvest research strategy. The pa­per then examines the results of the first twophases. Emphasis is on phase 2 activities dur­ing 1995-96.

Materials and Methods

Postharvest research at CIP has as its overallobjectives those of the Center itself, namely,to increase production and use of sweetpo­tatoo Postharvest research concentrates on va­rietal traits, raw material characteristics, pro­cessing techniques, and socioeconomic is­sues. The goal is to make processed productsmade from sweetpotato more affordable andnutritional and their production more profit­able. As such, postharvest research aims notonly to increase small farmers' and proces­sors' incomes from existing production, butto provide the incentive for the adoption ofyield-increasing, cost-reducing technologiesprovided by other areas of research at CIP.

As the planning of postharvest research onsweetpotato at CIP evolved in the 1990s, aglobal strategy with guiding principles gradu­ally emerged (Table 1). The strategy has fourphases, each with a specified but flexibletimeframe, set of activities, and expected out­puts, These phases are:

• Phase 1. Identification of problems andopportunities (1989-92).

• Phase 2. Evaluation of existingtechnologies and ex ante assessment(1993-96),

• Phase 3. Collaborative technologydevelopment, market research, andtraining (1997-2000),

• Phase 4. Enterprise development and expost assessment (2000-2003).

(IP Program Report 1995-96 265

Results and Discussion

Phase 1Phase 1 ended with the consolidation of a

global agenda for sweetpotato postharvestresearch that had been developed in collabo­ration with developing- and developed-coun­try partners. That agenda was now to focuson 7 of some 100 sweetpotato-producingcountries with the greatest processing poten­tial, at particular sites within those countries,and on three types of priority products (Table2). The products were starch, flour, and feed(i.e., roots and vines for pigs in Asia and vinesfor cattle in Africa and Latin America).

the more detailed review of recent results in

phase 2.The phases in CIP's strategy for

sweetpotato postharvest research closely re­flect at a global, or macro, level, the stepsinvolved in postharvest technology and mar­keting for root and tuber crops at the local, ormicro, level. Microlevel steps are: (1) prob­lem and opportunity identification, (2) re­search on products and processes, (3) pilotproject, and (4) commercial-scale expansion.Phase 3 involves interdisciplinary and insti­tutional collaboration, and direct involvementof users' groups (processors, consumers, andanimal producers) as active research partners.To ensure widespread effect, phase 4 bringsthe postharvest research results together withother aspects of enterprise development. Inthe following section we describe the out­comes in phase 1 to provide the context for

Table 1. Elemenls of (IP collaborative sweelpolalo research strategy.

1994

•

19921990

four research activities: (1) a macroreview ofChinese secondary data and associated lit­erature on production and use trends, (2) casestudies in a select number of provinces toanalyze county data on production and use,(3) a microlevel analysis of sweetpotato feeduse in Sichuan Province, and (4) the evalua­tion and improvement of small-scale process­ing of sweetpotato roots into starch.

The macroreview and provincial case stud­ies detected a recent reversal in the down­ward trend in area planted to sweetpotato insouth, southwest, and central China (Figure1). Sichuan Province in the southwest, whichhad become the largest pig-producing prov­ince in China, was suffering from a chronicshortage of feed maize. Farmers substitutedsweetpotato for maize in their hog rations asa resu It.

Small-scale processing of roots into starchfor noodles also had expanded tremendously,especially in Shandong and Sichuan Prov­inces. In Anyue County, Sichuan, for example,sweetpotato noodle production increasedfrom 3,000 to 26,000 t between 1990 and1996. Anyue noodles are marketed from thefar west of China to coastal cities. Urbaniza­tion and income increases in China appear

1988

Year

19861984

•

19821980

1600000

1550000

1500000

1450000

1400000

• •1350000 •

1300000

Phase 2Phase 2 of ClP's sweetpotato postharvest

strategy calls for a dichotomous approach.Macrolevel or regional studies look at themore long-term outlook for sweetpotato pro­cessing by examining existing or potentialpractices in light of production and use trends,prices, and trade patterns. This ex ante re­search seeks not only to assess the econom­ics of existing processing but also to set tar­gets for competitiveness and evaluate theprospects for achieving them. In keeping withthe guiding principle of building on localrural momentum (Table 1), phase 2 also callsfor evaluating existing technologies tocomplement the macrostudies. Key factorshere are drying and extraction rates, costs,and identification of the postharvest attributesof potential processing cultivars.

y =1.593E10 - 1.605E7x + 440.9542

AsiaChina. China produces about 85% of the

developing world's sweetpotatoes. Since theearly 1960s, the percentage of productionused for feed or processed products has risensteadily to over 50% of annual output. Rela­tively little information was available for pro­jecting future sweetpotato uses. A more de­tai led assessment of the potential forsweetpotato processing in China involved

1650000 -,-----------------------r----,

Figure 1. Sweetpotato sown area (ha) trends in southwest China, 1982-93.

266 Program 6

to be driving demand for better-quality starchnoodles, thus offering opportunities for small­scale processors to produce goods with highadded value. Collaborative research with theSichuan Academy of Agricultural Sciences(SAAS) focuses on quality improvement forboth starch and noodles, and involves linkswith food scientists at Hong Kong Universityand processing enterprises themselves.

Feed and processing together account forwell over 50% of use in most of the prov­inces studied and are clearly on the increase.Processing includes dried chips for feed, aswell as starch. Research in China carried outby the Australian Center for InternationalAgricultural Research (ACIAR) estimated thatthe expected benefits from sweetpotato werehigher than for any other crops except riceand wheat. Ninety-five percent of the pigsproduced in China are raised on small farms.The initial Center for Integrated AgriculturalDevelopment (ClAD)-SAAS farm-level analy­sis of pig production in Sichuan Provinceshowed that the traditional sweetpotato feedsystem used by small farmers is inefficient dueto nutrient-poor rations, which lead to lowpig growth rates and prolonged productiontimes. Adding appropriate feed supplementsto sweetpotato offers the potential to increaseefficiency and profitability on a small scale.

The composite picture of sweetpotato pro­cessing emerging from these studies is one ofa great deal of local innovation with tremen­dous potential for growth to the benefit of thepoorest households in rural China. Priorityresearch topics include efforts to improvetechnical efficiency in feed operations, andcommercialization studies to target the mostdynamic markets for starch and related prod­ucts.

Philippines. Ex ante impact assessment inthe Philippines focused on the potential forsweetpotato use as animal feed and flour. Thestudy notes that the limited demand for freshroots offers little incentive for sweetpotatoproducers to increase production.

Instead, the report identified a site in Cen­tral Luzon as the most promising site for

sweetpotato processing enterprises. Successwill depend on government policies to (1) fa­cilitate the adoption of high-yielding varie­ties with high dry matter content, and (2) im­prove processing efficiency. Since the studywas completed, the private sector has estab­lished medium-scale sweetpotato starchplants in Central Luzon, targeting high-valueexport markets for noodle production in Ko­rea. The performance of these enterprises,especially in relation to the supply of freshroots, will be relevant for assessing the feasi­bility of producing starch or other productsfor domestic markets.

Latin AmericaRecent research on sweet potato

postharvest issues in Peru resulted from thecollapse in prices paid producers in early1990 and the ever-increasing imports ofwheat flour. The private sector responded bypartially substituting raw, grated sweetpotatofor wheat flour in a new type of sweetpotatobread. Subsequently, exploratory researchprojects all provided positive indicators of thepotential for sweetpotato bread and otherproducts. Beginning in 1995, ClP coordinateda Dutch Ministry of Foreign Affairs (DGlS)­funded project on sweetpotato product de­velopment for flour, starch, and fol iage.

Resu Its from the work on sweetpotato as awheat flour substitute have been mixed. Theraw, grated method turned out to be hard tosustain on other than a novelty basis becauseof seasonal and year-to-year price fluctua­tions, and the logistics of securing and grat­ing regular supplies of fresh roots. Trade lib­eralization and the lifting of subsidies drovethe price of wheat flour down, not up as ex­pected. That made the substitution ofsweetpotato flour even more problematic.

On the other hand, ClP-supported researchfound the use of sweetpotato in flour-like formin a children's weaning food highly attrac­tive. This product is intended for mass distri­bution in the government-sponsored cam­paign to help eradicate malnutrition in themost vulnerable segments of Peru's popula­tion. The weaning food formula has attractedinterest by large-scale food processors. The

[IP Progrom Report 1995-96 267

cost of sweetpotato flour has resurfaced as akey issue, especially as the price of importedwheat flour has experienced some sharp pricehikes in recent months. The government­sponsored weaning food program also callsfor some 70-80% of the ingredients to be pro­duced domestically.

Sub-Saharan AfricaSweetpotato postharvest research in east­

ern Africa focused initially on poor, femalefarmers and women's groups engaged insweetpotato processing in the dry, westernpart of Kenya. Earlier consumer surveys andproduct testing had shown there was an in­terest in sweetpotato as a flour substitute. AClP multidisciplinary team and scientists fromthe Kenyan Agricultural Research Institute(KARl) at the outset faced the challenge ofdoing postharvest research with a crop that

people were remarkably unfamiliar withwhen it came to uses other than simply boil­ing it for direct human consumption. The col­laboration had two principal thrusts.

One involved using sweetpotato to makea variety of locally popular baked goods(chapatis, mandazis). Different ways weretried, but all were within the capabilities ofthe intended, limited-resource beneficiaries.These new uses for sweetpotato and the as­sociated simple processing techniques provedquite attractive. Some procedures were triedfor a while and dropped; others were quicklyadopted as income-generating activities,sometimes in modified form.

Another thrust was to improve nutritionlevels through a package of related initiatives.Among them was encouraging womensweetpotato farmers to plant varieties shownto do well under local growing conditions andto contain high amounts of beta carotene. Thiswould help overcome vitamin A deficiency,which is high in western Kenya.

Proposed work includes (1) improvingquality control, (2) incorporating the high betacarotene-contain ing varieties into processedproducts, (3) increasing the widespread dif­fusion of improved varieties and simple pro-

268 Program 6

cessing practices, and (4) conducting an expost appraisal of the effect of these initiatives.In addition, the technical and economic fea­sibility of using sweetpotato as an ingredientin composite flours needs to be assessed ifgrowers in western Kenya are to penetraterapidly growing urban markets in that part ofthe country and elsewhere.

Conclusions

Recent results from phase 2 encompass theevaluation of existing technologies and as­sessment of the potential for future commer­cial expansion of processing activities. Thiswork centered primarily on the seven targetcountries and the three priority products iden­tified in phase 1 (Table 2). We achieved thefollowing results:

• Documented the importance andpotential of postharvest activities.

• Generated initial impact through the readytransfer of existing skills and technology.

• Developed institutional linkages necessaryfor addressing the tasks in phase 3.

• Sharpened the geographic andproduct-specific focus of future researchon technology development.

• Empowered national scientists to achievetheir research objectives more quicklythrough training and workshops.

Based on these results, CIP's collaborativepostharvest research now enters phase 3.Greater priority will be given to work onstarch and roots for feed in Asia, and flourand fodder in Latin America and Africa.

Selected Reading

Cabanilla, L.S. 1996. Sweetpotato in thePhilippines: Production, processing, andfuture prospects. International PotatoCenter (CIP) and the University of thePhilippines at Los Banos, Lima, Peru.100 p.

Gitomer, C.S. 1996. Potato and sweetpotatoin China: Systems, constraints, andpotential. International Potato Center (ClP),Lima, Peru. 183 p.

CIP Progrom Report 1995-96 269

research and development. UPWARD, LosBanos, Laguna, Philippines. 1996.p.171-190.

Wheatley, C. 1996. Small-scale enterprises:What might the future hold for ruralhouseholds and root crops? In: Into actionresearch: Partnerships in Asian root crop

Ecology

Table 2. Sweetpotato research sites and products.

Enhancing the Role of Small-ScaleSweetpotato Starch Enterprisesin Sichuan, China

C. Wheatley!, Lin LipingZ, and Song Bofu3

Sweetpotato, Ipomoea batatas (L.) Lam., is amajor component of small-scale Chinesefarming systems, which produce more than100 million t of fresh roots annually. Sincethe 1960s, use of the crop has shifted fromdirect human consumption toward animalfeed and industrial uses. Shan dong andSichuan provinces, with annual sweetpotatoroot production of over 20 million teach,have developed important starch industriesbased on small-scale extraction of starch andits use in transparent noodles, which also areproduced largely on a small to medium scale.In Shandong, some 30-40% of sweetpotatoproduction is used for starch extraction; inSichuan, about 15%.

In Sichuan Province, where ClP hasworked with the Sichuan Academy of Agri­cultural Sciences (SAAS) for over 7 years, sig­nificant progress in upgrading the technologylevel of small-scale enterprises has beenachieved. Manual processing of the roots hasbeen largely replaced by small- and medium­scale mechanized equipment (root washers,grinders/raspers, horizontal and drum sepa­rators, and inclined channel sedimentation).The introduction of small-scale, single-screwextruders has allowed increases in produc­tivity and output of sweetpotato starchnoodles. Several items of equipment also usedfor potato starch processing are now manu­factured commercially and distributed be­yond Sichuan Province.

Sichuan is an inland province, distant fromthe booming coastal regions of China. The

1 CI P, Bogar, Indonesia.2 Crops Research Institute, Sichuan Academy of Agricultural

Sciences (SAAS), Sichuan, China.3 Chinese Academy of Agricultural Sciences (CAAS) and

CIP.

270 Progrom6

province is densely populated (110 millionpeople). Incomes are below the national av­erage: rural per capita annual income inSichuan was US$85.00 in 1993 (75% of na­tional average rural income, and only 29%of national average urban income). Conse­quently, Sichuan is now a major source ofeconomic migrants.

Increased use of sweetpotatoes in Sichuan,whether for feed or starch, offers real poten­tial for rural income generation in those ar­eas where sweetpotatoes are grown, andwhere the need for poverty alleviation isacute. SAAS and ClP research has, since1994, focused on evaluating the status ofsweetpotato starch enterprises and identify­ing opportunities for their further develop­ment. This has entailed integrating market andtechnical research.

Materials and Methods

Starch enterprise appraisalsThree starch enterprises in Santai County

were selected as case study un its on the ba­sis of ownersh ip type (private or collective),scale of operation (0.2-0.8 t fresh roots perh), whether manual or mechanized, and thestarch sedimentation method used (naturalsedimentation in tanks, sour liquid, or in­clined channels). Three batches offresh rootswere followed through the normal processoperations for each enterprise.

During November 1994, a participatoryappraisal of the small-scale starch extractionenterprises was carried out. Data on the tech­nical operation of the process, through directmeasurement and observation of normal op­erations, were complemented by relevant in-

formation on the food system in which eachenterprise operated.

Fresh roots of Xushu 18 from one field plotwere used as raw material for all appraisals.To determine the effects of differing raw ma­terial quality on technical performance andprocess economics, at Guanqiao enterprisefresh roots of Mianfen 1 were also processed.Mianfen 1 has a high fresh-root starch con­tent, but lower fresh-root yield, than Xushu18.

Technical performance of the enterprisewas evaluated on a batch basis (per kg freshroots processed), and then recalculated on aproduct basis (per ton dried starch produced).Most (60-80%) of the starch was sold or usedimmediately as wet starch cakes (moisturecontent 45%) for noodle production. For thepurposes of analysis and comparison, how­ever, results are presented as dry starchequivalents.

On a dry matter basis, prices for wet anddry starch are nearly the same. Drying isworthwhile only if the starch is to be mar­keted or stored.

Economic performance was determined ona per metric ton dried starch basis plus addi­tional revenues from the sale of moist resi­dues. In many cases the residues are useddirectly for pig feed by the same household,but for the purposes of enterprise analysis the1994 market price ($2.40/ton wet residue) hasbeen used.

Market researchA 1995 market survey, conducted jointly

by the Center for Integrated Agricultural De­velopment (ClAD) of Beijing AgriculturalUniversity and SAAS assessed the potentialdemand for sweetpotato starch in both foodand nonfood industries.

We used secondary information to developan inventory of Sichuan enterprises that usestarch as a raw material for the manufactureof food and other products, for selecting arepresentative sample of enterprises for inter­views, and for estimating starch demand in

Sichuan. The field study included sweetpotatostarch and wholesale markets, sample starchenterprises, and key informant interviews withscientists and industry leaders in Sichuan.

Process research for quality improvementDuring 1996, SAAS process research sci­

entists studied two ways in which small-scaleenterprises could improve the quality of thestarch they produce through (1) process modi­fications appropriate to their scale, and (2)use of different sweetpotato varieties.

Using Nanshu 88 in an orthogonal experi­mental design, the effects of varying the ratioof water to weight of fresh roots (3:1, 6:1, and8:1), mesh size during separation of starchsuspension from fibrous residue (80, 100, and120 mesh), and sedimentation time (8, 16,and 24 h) on starch yield and quality werestudied. Starch yield was calculated at stan­dard 14% moisture content.

Analyses of starch (Layne and Eynonmethod), lipid (Soxhelet extraction), ash (in­cineration at 525°C for 1 h), and protein(macro-Kjeldahl) of the dried starch sampleswere carried out by SAAS Central AnalyticalLaboratories. Whiteness was determined byfluorescence analysis, and by a sensory panel.

Similar analyses were carried out in a sec­ond experiment to determine the variation instarch purity across 10 sweetpotato varietiesor promising selections.

Results and Discussion

Starch enterprise appraisalsThe appraisal data showed that all enter­

prises were profitable with high returns oninvestment, despite low use of installed ca­pacity (Table 1), caused by problems in rawmaterial supply. In 1994, drought loweredsweetpotato production in Sichuan, and re­duced the length of the processing season.

The dry starch yield (14% moisture con­tent) ranged from 10% to 18%, depending onboth process and variety (Table 2). Improve­ments to process efficiency, especially at theseparation stage, would increase profitabil-

(IP Program Report 1995-96 271

232

15247

96.22.4

18.114.4

1461,75237.1

160.8

80.38-1.070.21-0.570.02-0.10

and Sichuan

Sweetpotato starchb

26415

96.22.4

13.112.4

Guanqiao(family)

Xushu 18 Mianfen 1

140.200.80

25637

293

100

Second grade

13.4

8.4

97.4

25.5

Xushu 18Xushu 18

Changping Gaoyan(household, manual) (collective)

costs (US$/ton dry starch)

Enterprise

Yield of dried products(1 ure content) as %

esh·roof weight

Table 1. Principal performance and profitability data from the three sweetpotato starch extraction enterprisesfrom Santai County, Sichuan, China, 1994.

Table 2. Starch quality (purity) specifications of Sichuan industries compared to the chemical composition ofsweetpotato starch produced by small-scale enterprises in Santai County, Sichuan, China, 1994.

272 Progrom 6

ity since more starch would be produced perunit of roots processed.

At Guanqiao enterprise, where two vari­eties were compared, Mianfen 1 yielded moredry starch and greater profits, allowing theenterprise to pay farmers a higher unit pricefor Mianfen 1 roots. The low labor costs, as aproportion of total costs, in the two mecha­nized enterprises are encouraging. Any futureincreases in labor costs should have a smalleffect on overall enterprise profitability. Useof higher starch varieties (such as Mianfen 1)by farmers should be encouraged by the pro­cessing industry, and adequate price incen­tives should be given, as justified by processeconomics.

Demand for starch processing equipmentis high. One of four starch processing equip­ment manufacturers in Santai County,Sichuan, reported that from 1992 to 1996sales of sweetpotato processing equipmentmore than doubled (240%) for starch extrud­ers, and nearly tripled (288%) for root wash­ers. The sales value of root washers, starchseparators, and extruders totaled overUS$180,000 in 1996, 85% of total agricul­tural equipment sales. Between 1992 and1996, sweetpotato processing equipmentsales were valued at $630,000.

Although neither sweetpotato productionarea nor volume changed appreciably be­tween 1989 and 1995 (production in SantaiCounty varied between 82,000 and 93,000t/yr), the proportion of sweetpotatoes thatwere processed increased from 36% to 76%.Of 91,000 t produced in 1995,69,000 t wereprocessed. That was accompanied by an in­crease of 70% in the number of pigs producedin the area during the same period (110,000in 1995). Pig production is closely Iinked tostarch processing through use of residues forfeed. .

Market researchThe results of the market survey were sur­

prising. Companies complained of severeshortages of maize starch (the major starchused) because of (1) insufficient maize pro-

duction in Sichuan itself, with demand formaize starch exceeding local supply by over100,000 t in 1995, (2) competition from thefeed industry for raw materials, and (3) diffi­culties in importing starch or maize from otherprovinces. This last problem was due to con­gested transport infrastructure and the un­availability of maize elsewhere in China be­cause the richer coastal provinces bought upavailable supplies for themselves.

This situation represents an opportunity forsweetpotato starch to fill a supply gap.Sweetpotato starch in Sichuan has consis­tently been priced below maize starch (Fig­ure 1). But sweetpotato starch extraction ona small scale is more profitable than maizeextraction on a large scale. At 1994 prices,the net profit on maize starch extraction was$35/ton compared with $60/ton forsweetpotato, even after including the incomefrom maize starch by-products.

Sweetpotato starch product quality, how­ever, was rated poorly by industry. The starchcontains impurities such as excessive mois­ture and ash (Table 1), and is not sufficientlywhite. Impurities can be reduced through pro­cess improvements. Shandong Province pro­duces refined sweetpotato starch using equip­ment similar to that in Sichuan by additionalpurification and drying steps.

Research for quality improvement ofsweetpotato starchMesh size and volume of water used were

found to significantly (P=O.OOOl) affect starchextraction rate and ash content of the ex­tracted starch. All treatments produced starchthat met maize starch standards for lipid andprotein impurities. Starch whiteness increasedwith increased volume of water used and finermesh sizes, but decreased with increasedsedimentation time. The ash content of eventhe best starch samples, however, exceededacceptable limits (lowest sample value:0.38%) (Table 2).

For both starch yield and product quality,the optimum processing conditions werefound to be 1:6 ratio of root weight to pro-

(IP Program Report 1995-96 273

0.653 b0.64600.594 {

0.492 f0.482 d0.460 a

0.408 9

0.392 h0.385 9

0.358e

Ash content

(%)

e

Breeding Section. Significant differences werefound between the 10 varieties tested forstarch content percentage, and lipid and ashcontent of the extracted starch (Table 3). Thissuggests a potential to improve starch puritythrough a varietal approach if the fresh-rootand starch yields remain attractive to farm­ers.

100 o Wholesale90 • Retail

80

70

60

50

40

30

20

10

01990 1991 1992 1993 1994 1995

Figure 1. Wholesale and retail price of sweetpatato starch as a percentage of maize starch price in SichuanProvince, China, 1990-95.

cess water, 120 mesh (finest size), and 8 hprecipitation. More efficient root washing toensure more efficient soi I removal before pro­cessing could reduce ash content of thestarch.

Starch was also extracted, under standardconditions, from 10 different sweetpotatovarieties/promising selections, from the SAAS

Table 3. Effect of variety on purity of extracted starch (14% moisture content). The varietal effect was significantfor all three parameters (starch, lipid, and ash contents). Letters denote mean separation at a=0.05.

274 Program 6

Conclusions

Any diversification of markets for sweetpotatostarch in Sichuan will depend upon produc­ing a product with greater purity than thatcurrently available in the market. Such a high­grade starch would also permit the produc­tion of noodles of higher quality and value.Recent private-sector investment in ShandongProvince points to improved starch quality asa prerequisite for producing export-qualitynoodles.

The starch and noodle agroindustry inSichuan is predominantly small scale. Theseru ral entrepreneurs have made sign ificantinvestments in equipment during the last fewyears, despite the strong seasonal nature ofthe business. The processing season may lastonly a few weeks from late October to mid­November each year. Such seasonality is un­favorable for the establishment of large-scalestarch extraction plants, which would remainidle for most of the year unless they were in­volved in processing other raw materials. Thatsituation provides an opportunity for smaller­scale enterprises to benefit from the expan­sion of market demand for starch in Sichuan,and for the development of noodle productsof higher quality and value.

The technical and market research activi­ties between CIP, the Chinese Academy ofAgricultural Sciences (CAAS), and SAAS willfeed into these and other efforts. Finally, closelinks have been established with regionalcenters of excellence in starch research (HongKong University and National University ofSingapore), which will assist in relevant tech­nical research and professional developmentof project collaborators in China.

Selected Reading

CIAO and SAAS. 1995. Potential for marketdiversification of sweetpotato starch andflour in Sichuan Province. Center forIntegrated Agricultural Development(CIAO) and Sichuan Academy ofAgricultural Sciences (SAAS), BeijingAgricultural University, Beijing, China.28 p.

Collado, L.S. and H. Corke. 1997. Propertiesof starch noodles as affected by sweetpotato genotype. Cereal Chem.74:182-187.

Marter, A.D. and W.H. Timmins. 1992.Small-scale processing of sweetpotato inSichuan Province, China. J. Trop. Sci.32:241-250.

(IP Program Report 1995-% 275

Feasibility, Acceptability, and ProductionCosts of Sweetpotato-Based Products inUganda

v. Hagenimana1 and C. DwarF

Sweetpotato (Ipomoea batatas) is one of threestaple crops in Uganda, but its postharvestuse is remarkably narrow and limited to hu­man consumption in a fresh, boiled form. Thesmall number of ways in which sweetpotatois used, and the limited processing technolo­gies avai lable and adapted to the area, do notpermit the potential benefits of the crop toreach farmers and consumers. Research onthe identification of potential markets, theassessment of consumer acceptabi Iity for newsweetpotato products, and the feasibility andadaptability of new recipes and processes areimportant in the widening of sweetpotato use.

Sweetpotato is grown everywhere inUganda. It provides a good part of the dietarystarch throughout the year. Fresh sweetpotatois consumed with sauces containing beans,cowpeas, or vegetables. Boiled or steamedfresh sweetpotato is the prevailing form ofconsumption. To a limited extent, sweetpotatois also ch ipped or crushed and dried for stor­age from November through January. Thedried sweetpotato is then boiled with saucesor tea, or milled into flour and mixed withmillet to process the local porridge calledatapa.

Myriad products can be made usingsweetpotato as a major ingredient, but someattitudes and cultural habits related to accept­ability of a new food product need to be over­come. Sweetpotato, either fresh, grated,cooked and mashed, or made into flour,could, with high potential for success, replacethe expensive wheat flour in making bread,chapatis (Indian-type flat bread), and

1 CIP, Sub-Saharan Africa region, Nairobi, Kenya.2 National Agricultural Research Organisation,

Kampala, Uganda.

276 Progrom 6

mandazis (doughnuts). Sweetpotato-basedproducts are of high quality and could com­pete with existing products on the market.

Th is paper reports the resu Its of a studyundertaken in Lira District, Uganda, to ex­amine the feasibility and profitability of par­tially substituting sweet potato cooked,mashed, or as flour for wheat flour whenmaking bread or buns, chapatis, andmandazis; and the acceptabi lity ofsweetpotato products by consumers.

The work was conducted primarily withinthe community together with women's groupsand individuals at Lira's main trading mar­ket.

Methods

The method used to collect information in thisreport was a combination of analysis of avai 1­able secondary data, informal interviews, for­mal questionnaires, and new product process­ing and taste testing by users.

The processing steps of the products hadto be adapted to the equipment and utensilsavailable. Members of the community wereasked to evaluate samples of a product con­taining sweetpotato and compare it to the typeof product just purchased or usually bought.Most people interviewed were from the Langoethnic group, and sweetpotato is their staplefood.

Results and Discussion

Food production and consumption in LiraAgriculture is the main economic activity

in Lira. Cotton once dominated as a cash crop,

but poor producer incentives and inadequatesupplies of cotton seeds have caused a bigslump in cotton production. Consequently,farmers are shifting their attention to other,new cash crop opportunities.

As a staple food, finger millet ranks firstfollowed by cassava, sorghum, andsweetpotato. Cassava, which was an impor­tant cash crop and famine reserve in the past,has been devastated recently by the high in­cidence of the African cassava mosaic virus.The price of cassava on the markets of LiraDistrict is now 7-8 times higher than in 1989.In contrast, the price of other major stapleshas only doubled or tripled. Hence,sweetpotato is becoming an important andcheap staple food in the district because ofcassava virus problems and the poor yield andother uses of finger millet and sorghum.

Varieties of sweetpotato inLira MunicipalityNeither sweetpotato retai lers nor buyers

pay any attention to variety in Lira. Duringour survey, there were heaps of sweetpotatoesin the market with red-skinned ones mixedwith white-skinned ones. The varieties werethe local varieties Tedo-Olokeren (white skin,white flesh), Luacer or Edopolap (red skin,white flesh), Mbale or Tanzania (white skin,yellow flesh), Anamuyito (red skin, whiteflesh), and Odyek-Awili (pink skin, whiteflesh). Tedo-Olokeren was by far the mostcommon variety. In Lira it is believed thatTedo-Olokeren is hard and resistant to wee­vil attack. It is also white, starchy, and flourywhen cooked as are most other varieties gen­erally preferred in Uganda. The price of freshsweetpotato in Lira's main market was fromUS$O.Ol to $0.02 per 1 kg (US$1.00 =1,000Uganda shillings).

Consumer food preferencesAs mentioned, finger millet along with sor­

ghum, cassava, and sweetpotato are the staplefoods of the area. Breakfast food is usually alight porridge made from a flour mixture offinger millet, sorghum, or cassava. Bread isnot a breakfast item, but a rare and expen­sive snack food. It is usually eaten with tea inthe evening. Its consumption was found to

be as important as that of mandazis. Chapatiwas not considered a snack; it was eaten forlunch or dinner as a main food of the meal.

From the ranking exercise for preferenceof avai lable foods on the market, sweetpotatoand bread ranked first, whereas chapatis andmandazis were fourth. About 25% of consum­ers interviewed ranked cassava second, butmost others ranked it sixth or seventh, mainlybecause of its current low availability. Irishpotato chips were less known in the area,because potatoes were not grown in areasnear Lira. These chips were ranked mostlylast like kabalagala (a sort of cassava-bananapancake).

Availability of baked and fried productsin LiraTable 1 lists the snack products and bread

sold daily in different markets of Lira Munici­pality. The activity of trading mandazis,chapatis, kabalagala, cake, and bread in­volves an exchange of about US$700/day,and the activity employs more than 100people. Half of trade is in bread and a thirdin mandazis.

During the survey, we noted that manyhouseholds baked buns. We counted 11 smalland locally made ovens for bun baking. Thebread sold in Lira is mainly locally processed,but there is also bread from Kampala, Jinja,and Kisumu (in Kenya).

The price of bread was US$0.60-0.80 fora 500-g loaf. But few people in Lira can af­ford to buy a whole loaf. Instead, bread wasbeing sold by the slice for $0.05 each;mandazis and kabalagala were also sold for$0.05 each and were popular in the munici­pal markets. Women were the major playersin selling fried and baked products.

Feasibility and acceptability trials forbaked sweetpotato productsFresh sweetpotato roots used for the trials

were purchased from Lira's main market.They were a mixture of white- and red­skinned varieties with white flesh.Sweetpotato flour was processed from driedsweetpotato slices purchased from a farmer

CIP Program Report 1995-96 277

Table 1. Fried and baked products sold in different markets of Lira Municipality, March 1995'.

o 0.01

0.010.01

0.010.010.010.01

o 0.010.01

26

Kabalagola

Sellers Quantity Price/unit

(no.) said (USS)

mashed sweetpotato significantly reduced oiluptake in mandazis (Figure 1).

a

was $0.60.Oth,,, hr,!,o" prodlucts, atthe nnarket were cakes

Acceptability was evaluated by compar­ing sweetpotato bread, chapatis, andmandazis (using sweetpotato flour or cookedand mashed sweetpotato to substitute forwheat flour) with similar products the con­sumer has just bought from the market or hadever tasted. Attributes such as overall taste,texture, freshness, appearance, sweetness,and color were judged subjectively by bread,chapati, and mandazi consumers. Consum­ers were informed that our products containedsweetpotato as an ingredient.

The results (Figure 2) show that bread,chapatis, and mandazis containing cookedand mashed sweetpotato were preferred byconsumers for taste, texture, freshness, ap­pearance, sweetness, and color. Consumersexpressed a willingness to pay the same price

Chapotis

Price/unil' Sellers Quantity Price/unit

sold (USS)

in Lira Municipality, then ground in the usualhammer mill. The wheat flour was that usu­ally used for bun- or bread-making in LiraMunicipality.

Bread-baking, chapati, and mandazi pro­cessing trials were conducted under localcommercial conditions using a mixture con­taining various proportions of wheat flour,sweetpotato flour, or cooked and mashedsweetpotato roots. The recipes used havebeen reported elsewhere.

Because chapatis and mandazis are deepfat-fried, the amount of fat absorbed by theproducts is nutritionally and aestheticallyimportant and influences production costs. Inthe experiment to determine whether differ­ences in fat absorption varied by the form ofsweetpotato (boiled and mashed, raw andgrated, or dried flour), we found that substi­tuting 50% of wheat flour with boiled and

278 Program 6

o Chapali

o Mandazi

30% substitution(sweetpotato flour)

Baked and fried products having sweetpotatoas an ingredient are highly acceptable to thecommunity. Cooked and mashed sweetpotatoas an ingredient improves the taste, texture,

Conclusions

compared with the cost of ingredients of tra­ditional mandazi recipes that incorporatesweetpotato. Table 2 compares net revenuefor chapatis, mandazis, buns, and bread madeusing only wheat flour and sweetpotato, andshows a significant profit increase whensweetpotato is used.

0.0070.058

Level of substitution and sweetpotato

0% substitution 50% substitution 50% substitution(boiled and mashed) (raw and grated)

5

0-+---,---

10

15

20

(IP Progrnm Report 1995-96 279

Oil (g/100 9 sample)

Table 2. Comparative gross margins of sweetpotato products and wheat flour products, Lira, Uganda.

A

Production costsThe data collected during the study indi­

cated that it was cheaper to producesweetpotato bread or buns, chapatis, andmandazis than to produce similar productsusing 100% wheat flour. This was mainly dueto the reduction in the amount of wheat flour,sugar, and oil required to make mandazis

for sweetpotato products as for similar prod­ucts they had been buying. Figure 3 showsthe sales trend for sweetpotato buns at awomen's group kiosk in Lira over a 7-moperiod.

Figure 1. Oil content in processed sweetpotato products. (Means followed by common letters for the same productare not significantly different at the 5% level by LSD.)

Color

Oiliness

Oiliness

Color

Color

Sweetness

Sweetness

Sweetness

Tex1ure

Texture

Texture

• Chapati usually bought"" Cooked and mashed sweetpotalo chapal;

10 Sweetpolato flour chapal;

• Bread usually bought'~j Cooked and mashed sweetpotato bread!mil Sweetpotato flour bread

• Mandaz; usually boughtrm Cooked and mashed sweetpotato mandazi'" Sweetpolato flour mandaz;

First choice

First choice

Appearance

First choice

Freshness

Freshness Appearance

Freshness Appearance

Tasle

oTaste

o

o

20

80

40

60

Taste

60

40

20

60

20

40

Answers (%)100

Answers (%)

80

Answers (%)

80

Figure 2. Consumer acceptability of baked and fried sweetpotato products.

280 Program 6

O+--+--...,...--+---r---1----t---1---t---I--.....,.--+-.....,.--t----rMay96Apr 96

---e- Pure wheat buns

~ Sweetpotato buns

Mar 96

(IP Program Report 1995-96 281

Hagenimana, V. and C. Owori. 1996.Feasibility, acceptability, and productioncosts of sweetpotato baked products in LiraMunicipality, Uganda: Astudy report. OP/NRI and NARO, Nairobi, Kenya.

Hagenimana, V., E.G. Karuri, M.A. Oyunga.n.d. Oil content in fried sweetpotatoprocessed products. ). Food Proc. Pres.(In press.)

Wheatley, c., G.). Scott, R. Best, and S.Wiersema. 1995. Adding value to root andtuber crops: A manual on productdevelopment. Centro Internacional deAgricultura Tropical (OAT), Cali,Colombia. 166 p.

Feb 96Nov 95Oct 95Sept 95

40

20

10

50

30

Bashaasha,B., R.O.M. Mwanga, C. Ocittip'Obwoya, and P.T. Ewell. 1995.Sweetpotato in the farming and food sys­tems of Uganda: A farm survey report. CIPand NARO, Uganda. 63 p.

Unsold buns (%)

60

Figure 3. Percentage af unsold buns for the 1st day on the market at women's group kiosk, lira. Sweetpotatobuns accounted for one-third of total buns.

Selected Reading

freshness, appearance, sweetnesss, and colorof bread or buns, chapatis, and mandazis. Italso significantly reduces oil uptake inmandazi and chapati processing. Sweetpotatoflour is easy to store and process, and is highlyprofitable. Still, much more fundamental re­search is required to upgrade the quality ofsweetpotato-based fried and baked products.

282 Progrom 6

Quang Nam Da Nang

9u~n2~h<:i

Ho Chi Minh City

Since the mid-1980s, however, public-sec­tor research agencies have been worki ng tointroduce the processing innovations thatwere developed in villages around Hanoi toother parts of the country. The mixed resultsfrom those efforts led ClP and several inter­national and national research partners tobegin an assessment, in 1995-96, of currentuse of root crops in four key sites in northand central Vietnam (Figure 1). The sites werein Sac Thai, Hatay, and Thanh Hoa Provincesin the north, and Quang Nam Da Nang Prov­ince in central Vietnam.

Sweetpotato and cassava are the two mainroot crops grown in farming systems in northand central Vietnam. Edible canna is less im­portant, but was included in the study be-

The Potential of Root Crop Processing forRural Development in Vietnam

G. Prain!, C. Wheatley2, and Nguyen Day Dud

LegendSac Thai = Main research site~o_n !-l'!..= Secondary site

1 CIP, Los Banos, Philippines.2 CIP, Bogar, Indonesia.3 Post Harvest Technology Institute, Hanoi, Vietnam.

Vietnam is a leading world producer ofsweetpotato (Ipomoea batatas) and cassava(Manihot spp.), and is probably the globalleader in area planted to edible canna (Cannaedulis). Historically, these crops were impor­tant seasonal, supplemental, and emergencyfood sources, but in the past 15 years, theyhave begun to assume greater importance asraw materials for value-added processing.Feed and starch are the dominant intermedi­ate processed products. Pork, transparentnoodles, candies, and baked goods are com­mon end products. The expanded process­ing activity has been almost exclusively basedon household initiative.

Figure 1. Provinces in north and central Vietnam where root crop utilization research was conducted.

cause of its Andean root crop ancestry andits importance in noodle making.

The majority of farm households in theprovinces under study depend on crop-live­stock systems to secure a rice-based food sup­ply for the household as well as cash income.Both food and cash depend on an adequatesupply of manure for the crops and an ad­equate supply of feed for the animals. Whenprocessing is undertaken for additional in­come, it provides a further supply of feed inthe form of by-product, but it increases de­mand for raw material.

In Thanh Hoa Province, fresh consump­tion of sweetpotato by producer householdsdeclined from around two-thirds to one-thirdof total production from 1980 to 1994. A simi­lar decline is also evident in cassava, but thechange of function of these two crops hasbeen different. Whereas the primary functionof sweetpotato has shifted from householdfood to household animal feed, cassava hasbecome a cash crop. It is grown primarily asraw material for the growing processing in­dustry, but the processing by-product finds aready market as animal feed.

Sown area and production trends for cas­sava over the past ten years show a gradualdownward trend throughout the period in allfour provinces (Figure 2). The abrupt declinein cassava in Hatay, which is close to Hanoi,can be attributed to a switch to sweetpotatoby some farmers and a move from cultiva­tion to more lucrative food processing andnonfarm enterprises. A strong upward trendin sweetpotato began around 1990, especiallyin Hatay and Thanh Hoa, where it is increas­ingly cultivated for pig feed.

Role of R~ot Crops in Pig Raising

From 1985 to 1995, pig liveweight in thenorth rose from 299,000 t to 580,000 t; percapita pork consumption more than doubled.The massive increase in sweetpotato area inHatay, from 5,000 ha to more than 20,000ha between 1990 and 1993, is directly attrib­utable to the use of sweetpotato for feed.

Pig-raising systemsTwo household-based pig-raising systems

prevail with different implications for pig feedresearch. In one system, piglets are fattenedfor slaughter. Many households combinethese systems (Table 1).

In Da Nang, households commonly con­centrate only on breeding piglets, partly be­cause of better access to the piglet markets ofsouthern Vietnam and Laos. Fattening is themore common practice, especially in themore remote, poorer areas of the north. InBac Thai, for example, there is an average ofthree fattening pigs per household, whereasonly one in four families has a breeding sow.In high mountain areas of Bac Thai, ThanhHoa, and Da Nang, cattle are more commondomestic animals, mainly because of theavailability of open pasture.

There is considerable variation in the num­bers of pigs managed by different households(Figure 3), which is an important consider­ation in technical intervention. Families fat­tening only one pig are least likely to be in­terested in innovations. With more pigs, im­proved performance becomes commerciallyattractive.

Da Nang again stands out as different fromthe other sites. Not only do many householdshave two or more breeding sows, many morehouseholds are fattening only one piglet. Thatsuggests the low priority and noncommercialcharacter of fattening in Da Nang.

Bac Thai and Hatay have similar numbersof households engaged in fattening. Both ap­pear to have greater commercial pig-raisingthan Thanh Hoa. In Hatay and in Thanh Hoa,of households fattening more than four pigs,only five have more than 10 head, and ofthose the largest operation has 40 head. Theseare the only large-scale pig-raising enterprisesencountered, emphasizing the backyard char­acter of most pig-raising.

Feed regimesThe two most notable findings about swine

feed regimes are (1) the dominance of

OP Progrom Report 1995-96 283

1995

1995

-D-Da Nang

-0- Thanh Hoa

-I:s- Bac Thai

~Hatay

1990

1990

O+--.---r---,----,-----y----,---.-_-.-_-,------,

1985

Year

250

200

150

100

50

50

100

150

200

Sweetpotato

300 1,000 tons

Cassava

250

Figure 2. Sweetpotato and cassava production in four provinces of Vietnam, 1985-95.

284 Progrom 6

_ F 1 head

1m F 2-4 head_ F > 4 head

Cl B 1 head

Cl B 2-4 head

9

147

Da Nang

Households (no.)

(IP Program Report 1995-96 285

On the coastal plain of Thanh Hoa,sweetpotato roots, both fresh and dried, aremuch more important as feed than at othersites. This is an area with as many as threeharvests of sweetpotato per year and wherestorage of dried sweetpotato chips is relativelycommon. Sweetpotato vines are also impor­tant as feed.

the by-product from starch-processing vil­lages accounts for up to 80% of total feed, incombination with root crops. A large part ofthe root crop component, however, is vinesrather than roots.

Thanh HoaHatay

8

21

o

20

Bac Thai

40

10

60

50

30

70

Total households (%)

Cassava is the most important feed com­ponent in mountain households. In Hatay,

Vines are the most important componentof pig diets in 7 out of 12 pig-rearing house­holds in Sac Thai. In one case, vines ac­counted for 45% of the approximately 2.4 tof feed given to a single animal over a 12-mogrowing period.

Figure 3. Pig-raising systems among case households in four provinces of Vietnam, 1995. (F = fattening,B= breeding.)

sweetpotato vines over roots, and (2) the lim­ited use of protein-rich supplements, even incoastal areas where fish by-products are rela­tively cheap.

Table 1. Pig-raising strategies in case households of four provinces, Vietnam, 1995.

The feed regime also varies in Da Nang.In the plains, 75% of feed consists ofsweetpotato vines and small roots, whereasat higher elevations cassava by-productdominates, although sweetpotato vines stillaccount for about 30% of total feed. Vinesdominate over roots in Da Nang because ofthe concentration of households maintainingsows to produce piglets. Fresh or dried vines,cooked with other vegetative by-products,provide a better diet for piglets than roots.

Socioeconomic importance of pig-raisingIn the plains of Sac Thai and in the Red

River Delta, pig-raising contributed on aver­age about 40% of income in case householdsin 1995, ranging from as little as 15% to ashigh as 64%. However, the purpose of pig­raising in Sac Thai is not primarily to gener­ate direct income. Pig-fattening offers a wayto convert nonfood farm output into manureand marketable pork using surpluslabor-that of the elderly, the young, and thelimited spare time of women.

Households that keep breeding sows fol­

Iowa different strategy. For instance, in DaNang farmers seek to reduce feed costs anduse of nonfood farm output, and to reducethe risk of disease, by selling off piglets early.This system tends to generate less manure forthe crop operation. This profit-oriented butrisk-averse approach works well in the spe­cial circumstances of Da Nang, with its goodIinks to piglet markets.

The highest profits were made by familiesthat had combined breeding and fattening pigoperations, and by those with the most an i­mals.

Constraints and opportunitiesPig fattening and piglet breeding pose dif­

ferent constraints and offer different opportu­nities for intervention in root crop-based feed.

Households involved in multiple pig-fat­tening are interested in increasing the volumeof feedstuffs produced on-farm, feed conver­sion characteristics of their animals, and therate of weight gain. In Thanh Hoa, the far­row-to-finish time ranges from 6 to 12 mo.

286 Progrom 6

The difference is largely due to diet, both thevolume of feed and the inclusion of protein­rich supplements. There are clearly opportu­nities here for exploring improved vine androot productivity and for evaluating alterna­tive feed regimes.

Starch and Noodles:Prospects for Sweetpotato

Starch production in northand central VietnamMajor sources. The two major sources of

starch in north and central Vietnam are cas­sava and canna; sweetpotato is only a minorstarch source at present. Cassava is by far thelargest and cheapest source and small-scaleprocessing occurs in most provinces (Table2). Canna starch processing occurs on asmaller scale, primari Iy for the specialty pro­duction of transparent noodles. Canna starchenterprises were found in a few villages inSac Thai and Thanh Hoa close to areas wherethe root was grown; canna processing is notdone in Da Nang. In northern Vietnam, mostcassava and canna starch production is con­centrated in five villages in Hoai Duc Dis­trict, Hatay Province, near Hanoi. A total of5,679 households were processing cassavastarch in 1995, consuming between 100,000and 200,000 t of roots to produce around50,000 t of starch. In the same area, 276households processed about 34,000 t ofcanna into 7,500 t of starch in 1995.

Processing efficiency. The procedures toextract starch from cassava, canna, andsweetpotato are simple and cheap. Roots arewashed (cassava roots are peeled first to pre­vent starch discoloration), grated, and filteredthrough cloth into a concrete container ofwater to make a sl urry. The slurry is fi Iteredfour times and then allowed to settle for 6 h(longer in winter). The water is drained, leav­ing wet starch of 35-45% moisture content.

From 100 kg of cassava roots, about 42 kgwet starch can be extracted, yieldi ng about28 kg dry starch. Canna roots convert to 28­30 kg wet starch from 100 kg fresh wt, yield­ing 21-23 kg dry starch. Sweetpotato has thelowest extraction rate, yielding 25-30 kg wet

2.19

1

1.49

Net profit

(US$)

7.27

By-

Income (US$)

starch product

Black

6.36

Starch

Canna starch and noodle processing isundertaken on a small scale in Sac Thai andThanh Hoa, but the major production area isthe same intensive processing district of HoaiDuc, Hatay. Unlike cassava-based process­ing, with its clear division of labor betweenstarch producers and maltose processors,

Transparent noodle supply and demandPer capita noodle consumption in Vietnam

in the early 1990s was 12-20 kg; transparentnoodle may represent 10-15% of that. Themost common raw material for transparentnoodle over the past 30 yr has been cannaroot.

(IP Progrom Report 1995-96 287

Sweetpotato could be an alternative sourceof bulk starch in the north. At present there isalmost double the quantity of raw materialavailable (1.8 million t compared with 1 mil­lion t of cassava). However, the low starchextraction rate of sweetpotato makes cassavaultimately a cheaper raw material.

Though profitability is quite low for cas­sava starch processors, it represents about60% of annual income for some households.In Thanh Hoa, the processing season runsfrom October to March. Average processingduring the season for the case households isabout 30 t of fresh roots, which yields justunder $400 income.

TotalOtherlabor

Costs and benefits vary greatly among thecassava processors studied. Hatay processorshave high transportation costs, which in­creases the price of the roots. But that is partlycompensated for with higher processing effi­ciency. The profitability in Bac Thai is due toa higher selling price for wet starch ofUS$0.16/kg, compared with between $0.12and $0.13/kg at the other sites, and a muchhigher valued by-product.

The concentration of processing house­holds in one area in Hatay increases the effi­ciency of transportation, making it feasibleto truck in fresh roots from up to 320 km away.It also facilitates the specialization of process­ing activities among households and the ex­change of products and services. The largevolume of final products generated enters acomplex marketing system of processed prod­ucts throughout north and central Vietnam.Consignment arrangements are common inthis system between processors and traders.

Cassava processing benefits. Producers offresh cassava and canna and a variety of as­sembler and transport businesses supply theroots over long distances for sale to starchprocessors in Hoai Due.

starch or 17-20 kg dry starch from 100 kg freshwt, depending on variety and time of year.

Table 2. Costs and benefits' of processing 100 kg of cassava roots into starch in four provinces of north andcentral Vietnam, 1995.

Net profit

(US$)

7.32 1.626.74 1.437.00 1.70

01 USSO.30/kg in 8ocThai, and

ofi~ fibrousness. It iSjJsed mostly

By TotoI-productC

other calculations, the Thanh Hoa calcula­tion failed to include depreciation and un­derestimated costs for fuel and other inputs.The relatively low profitability of noodle pro­duction in Sac Thai is caused by a muchlower conversion rate from starch to noodle,which is due to a different and less efficientprocessing technology that uses manual ex­trusion rather than steaming.

The potential of sweetpotato starch innoodle enterprisesThe relatively narrow adaptation of canna

at high altitudes, its remoteness from process­ing areas, and the long growing season meanthat the supply of raw material is limited to afew months. Sut the period of raw materialsupply coincides with the period of highestdemand for the starch, leading up to the NewYear celebrations. Therefore, prices remainhigh, even during this glut period.

These raw material supply problems, how­ever, have resulted in very little explorationof sweetpotato as an alternative. This is de­spite the proximity and stable supply of thecrop-there are three harvests a year in someareas-and the limited fresh root market forsweetpotato, which frequently results in de­pressed prices.

canna starch and noodle processing is oftencombined. Of the 276 starch-producinghouseholds in Hatay, 230 also producenoodles using their own starch.

The long growth duration of canna, usu­ally from March to November, means thatthe processing season is quite short, gener­ally from November to March or April. Al­though this covers the period of the Vietnam­ese New Year when noodles are most in de­mand, it limits the opportunities for optimiz­ing investment at other times of the year.

In Sac Thai, where up to a ton of fresh rootscan be processed in a day, average net prof­its of case households were around $16/d(Table 3). This compares to around $l/d foragricultural laborers. The bulk of starch andnoodle demand is met from Hatay, thus in­flating the costs of the final product in areasbeyond Hanoi. The lower profitability ofstarch from Hatay reflects both the more ex­pensive raw material, trucked in over largedistances, and a lower starch price.

Table 3. Costs and benefitsO of processing 100 kg of canna roots for storch in three provinces of north Vietnam,1995.

Noodle processing clearly offers the high­est returns of the processing activities stud­ied (Table 4). The net benefit recorded inThanh Hoa may be overestimated. Unlike the

288 Program 6

• evaluating genetic material for highfoliage production and high proteincontent for use in pig-fattening enterprises,

• evaluating genetic material for high drymatter,

• assessing the use and costs of available

As a result of the appraisal of the use ofroot crops for pig feed, starch, and noodles,two projects have been established. The firstproject involves:

CIP Progrom Report 1995-96 289

The enormous opportunities for economicdevelopment in Vietnam are mostly generatedat the base, among rural households. The roleof agriculture is increased productivity, ofcourse, in addition to value-added productsmade available through processing. The pro­cessing of root crops for pig feed, starch, andnoodles is an important part of that process­ing potential.

Conclusions and Opportunities

Almost all of the sweetpotato/canna noodleproduced so far has been marketed andpriced as canna noodle. In focus group dis­cussions with a stratified sample of consum­ers in Hanoi during 1995, high-income con­sumers reacted negatively to sweetpotato asa raw material. But medium- and low-incomeconsumers, who were more concerned withnoodle quality than sweetpotato's image,gave a positive evaluation.

Using sweetpotato starch, however, in­volves more work and processors require alower price for sweetpotato starch to justifythe extra effort. In addition, the supply ofsweetpotato starch remains a problem and isnot yet stable.

In 1996, pilot work on starch production,begun earlier in a southern district of ThanhHoa Province, transferred to Hoang Hoa,nearer the provincial capital. Twelve house­holds have enthusiastically adoptedsweetpotato and canna starch production, firstto supply noodle processors in Thanh HoaCity, and more recently to produce noodlesthemselves.

Technology development and participatorypilot studies in Hatay and Thanh Hoa Prov­inces have shown that it is technically fea­sible and profitable to use sweetpotato starchin transparent noodles. Using lime duringstarch fi Itration improves separation andyields a whiter starch. And combining cannastarch with sweetpotato starch overcomes thebrittleness of 100% sweetpotato.

The reluctance has been due to technicaland cultural factors. Sweetpotato has a lowerstarch content than canna and the extractedstarch has a grayish color. The noodles madefrom the starch also tend to be more brittle.Sweetpotato is also perceived as a food andfeed crop, not an industrial raw material.

Table 4. Costs and benefits' of processing 100 kg of canna starch into transparent noodleb in three provinces,

Vietnam, 1995.

protein supplements to energy-basedsweetpotato and other feed, and

• exploring alternative ways of preparingfeed to improve digestibility and quality.

The second project aims to improve theefficiency of sweetpotato and canna for starchand noodle processing. It involves:

• supporting pilot units for sweetpotatostarch and noodle production,

290 P,og'Om 6

• evaluating new sweetpotato cultivars forpotential in starch processing,

• evaluating new canna varieties for use instarch and noodle production, and

• supporting improved marketing linkagesbetween starch producers and noodleproducers.

C. Leon-Velardel, J. Rocal, J. Arteaga2, L. Quispe2

,

and A. Parraga2

Perspectives on Sweetpotato:Dual-Purpose Varieties

As a consequence, we need uniform datacollection over time from germplasm plots to

We first established a preliminary classifica­tion for dual-purpose varieties based on therelative contribution of foliage and roots todry matter (OM) content. Then we looked athow crop management affected the partition­ing of OM in foliage and roots in five clonesidentified as having dual-purpose potential.

Relation of roots and foliageA data set of 1,1 68 accessions from the

germplasm collection held at ClP was ana­lyzed in 1995 in La Molina, Peru, to estab­lish a preliminary classification for dual-pur­pose varieties. We identified potential dual­purpose varieties based on the ratio of rootto foliage (R!F) contributions in the produc­tion of total DM. Calculated values of R/Franged from 0 to 4, but in some cases actualvalues exceeded the values in the range con­sidered. As a result, we deleted 11.8% of theinformation. The extreme values resultedwhen in some cases a group of two or threeplants was considered as one plant. Whenthe germplasm collection was being evalu­ated, some varieties produced roots morequickly, whereas others did not.

(IP Program Report 1995-96 291

ing the roots for human food. Because thereis little information on the management ofdual-purpose clones, this work focused on de­termining a preliminary roots-forage classifi­cation, and on developing management strat­egies for dual-purpose sweetpotato varieties.The work was done jointly by CONOESAN!ClP and the Universidad Nacional AlcidesCarrion, Oxapampa, Peru.

Materials and Methods

In the tropics, one of the main limitationsto small farmers in mixed crop-livestock pro­duction is a reliable, year-round supply of feedand energy. Sweetpotato might help to over­come this limitation with minimal environ­mental damage. However, small farm sizeand low income from the crop limit the areagrown to sweetpotato for use in livestock pro­duction only.

On small crop-livestock operations, dual­purpose sweetpotato clones hold a compara­tive advantage over single-purpose varietiesgrown for roots or for forage. In an optimalintegrated livestock management system,farmers cou Id take advantage of sweetpotato'sregrowth ability by continually or periodicallyharvesting the vines for animal feed through­out the growing season before finally harvest-

The germplasm collection held at ClP in­cludes a large group of sweetpotato clonesand varieties. Breeding efforts concentrate onroot production, with emphasis on dry mat­ter content, flour, and starch. One group ofclones, however, produces mostly forage withlow root production, which makes it ideal foranimal feed. Although in recent years demandfor these clones has increased, root produc­tion is also necessary for human food and asan income component of small crop-livestockfarms.

1 CONDESAN/CIP, Lima, Peru.2 Universidad Nacional A[cides Carrion, Oxapampa, Peru.

Sweetpotato (Ipomoea batatas) is one of 12main plant species used as human foodthroughout the world. The roots are used forhuman and animal consumption, and thevines are generally used for animal feed alongwith crop residue and unmarketable roots.

0.011.24 ± 0.031.74 ± 0.032.45 ± 0.033.47 ± 0.03

Foliage RtFnt)O

3.700133.58 ± 8.770104.79 ± 10.29 b

8.27 b68.19 ± 10.68 c

acommon letter are not significantly different

Management effects on R/FThe frequency of cutting forage from the

growing crop is the main management fac­tor. For livestock production, several cuttingsof foliage are required throughout the crop­growth period, even though root productionis sacrificed. When crop, rather than forage,production is most important, root develop­ment is paramount.

However, in the crop-livestock operation,both foliage and roots are desirable. There­fore, we evaluated potential dual-purposeclones to determine the effect of foliage cut­ting frequency on forage and root production.

Five clones were evaluated: DLP-3548,R/F 1.43; ARB-265, R/F 0.51; ARB-142, R/F0.42; RCBIN-5, R/F 0.20; and ARB-UNAP55(cv. Helena), R/F O. The evaluation was car­ried out in Oxapampa, Peru, in 1996 duringthe dry and wet season, at 1,850 m abovesea level. The zone presents an average tem­perature of 16°C and annual rainfall of 600mm. Soils are neutral to slightly alkaline.

A split-plot design was used with the fiveaccessions in the main plot, and foliage cut­tings at 45, 90, and 135 d as treatments insubplots. Six cuttings were made at 45-d in­tervals, three at 90-d intervals, and two 135d apart. DM and protein content were ana­lyzed.

This work indicates the potential of cropvarieties from low root production or highdual-purpose categories to perform well as adual-purpose crop. A multivariate analysis(analysis of principal components) showedthat the group of accessions classified withinthe range established (Figure 1). The foragecategory shows a wide dispersion, whereascategories 3 and 4 are grouped together,showing the potential of the accessions fordual-purpose use as well as for root produc­tion.

Table 1. Classification of sweelpotato dual-purpose varieties based on the relation of rools and foliageproduction of dry matter' , Clp, La Molina, 1995.

Table 1 shows a classification scheme offive categories based on R/F, ranging from 0,indicating no roots present, to 3-4, indicat­ing high root production. There is some over­lapping of categories on root and foliage pro­duction. Categories of low dual-purpose andhigh dual-purpose showed no significant dif­ference for root production. Similarly, catego­ries of high dual-purpose and low root pro­duction showed no significant difference forfoliage production.

accurately classify potential dual-purposevarieties based on R/F. We also need tocomplement that information with otherbioeconomic characteristics not included inthis preliminary classification. Systematizedinformation of that type will be valuable forbreeding to produce primarily roots, prima­rily forage, or roots and forage.

292 Program 6

Figure 1. Graph of 1,168 sweetpotato accessions classified within five dual-purpose categories and plottedconsidering two principal components. The five categories are 1, forage; 2, low dual-purpose; 3, highdual-purpose; 4, low root produdion; 5, high root produdian.

(lP Program Report 1995-96 293

Table 3 shows the management effects ofcutting frequency and ferti lization on cloneARB-U NAP55. Although there is a positiveeffect of fertilization at rates of 60, 120, and180 kg/ha N, OM production decreases withincreased cutting intervals. A similar reduc­tion in OM production was observed whenthe clone was evaluated for dual-purpose use.Although fertilization increases OM produc-

The clone ARB-UNAP55 requires specialmention. This clone is considered to have anR/F of 0, being strictly considered a foragevariety. However, in certain zones such asOxapampa and in Africa, it has been foundto produce some roots, which may be evi­dence of a genotype x environment interac­tion. In this study, the R/F of ARB-UNAP55 isless than that of the other clones evaluated,and close to O.

11

11

.11

.11 .11 .

111.1. 1 .

111.1 . I 1.12 -

1 -

11-

111

1111.

111111 1111111.111 .. 1111111.11.1 111111 1 . 1 2

11 111 1. 111 . 111 2111 11 111 1111 11.1 1 1 2 ..22. 2.

1111111111.11 11111.1 . 22 2.1111111111111.1.111222 2 . 2.2 2.2.11111111111.111111222222.222.. 2211111111111 1222222222 222.22 2 3 3 3 3 3.

1111111111222222222223223333 333 33 3.111111123223233233333333333333 3 .•112225333344444434443334444.34 4 . .44 4 4 4.4

5445555455544444444 44 44.44 .4 4 .4 45555555555.4554454.4.4 4 4.4

555 5 555.555 5. 455555 5..

. 5. 4-2 - 5-ffJfffJf.rfHff.fJfrff.f.ff.fJ-frH.fHfffr.f.ffHHfrffffJfHrfHff.fJ.trfHfir

-2 -1 0 1 2 3 4 5PRINI

-1 -

PRIN25 -

Results

Table 2 shows total OM forage production atcutting frequencies of 45,90, and 135 d. For­age production was significantly higher(P<O.Ol) in cuttings at 90-d intervals than incuttings at 45- and 135-d frequencies. Cut­tings at 45-d intervals give good forage pro­duction, but root production is ni I. A cuttingfrequency of 90 d appears to strike a reason­able balance between forage and root pro­duction. A cutting frequency of 135 d in­creases root production but decreases forageproduction. R/F values increase as the inter­vals between cuttings increase, thus indicat­ing better root formation. R/F values are withinthe range described in Table 1. The choice ofa cutting frequency depends on whether for­age or root production is the objective of themixed crop-livestock farm.

0.82

0.85

0.631.350.37

9.1

8.06.2

180

8.3

6.77.9

135

9.7

10.5

5.9

Forage" Roots"

120

0.160.23

0.15

90

3.7

Roots"

purpose varieties should include those char­acteristics that favor livestock production.

Selected Reading

SAS (Statistical Analysis Systems). 1986. SASsystem for linear models. 1986 edition. SASInstitute Inc., Cary, North Car. 211 p.

Scott, G.). 1991. Sweet potatoes as animalfeed in developing countries: Presentpatterns and future prospects. In: Roots,tubers, plantains and bananas inanimal feeding. Animal Production andHealth Papers95. FAO, Rome. p. 183-189.

Woolfe, ). 1992. Sweet potato: An untappedfood resource. Cambridge University Press,Cambridge, U.K. 214 p.

offorage production ranged from 13.1 %to 16.1%; percentage

60

Frequency (days)

R/Fb Forage"

45

Forage" Roots"

Table 2. Average production of dry matter in t/ha of forage and roots in five sweetpotato dual-purpose clones,and the relation of roots/forage (R/F), Oxapampa, 1996.

Table 3. Total production of dry matter (t/ha) of clone ARB-UNAP55 (cv. Helena) at different levels of Nfertilization and different cutting frequencies, San Ramon, 1996.

tion, the cost of this input must be consid­ered in any technological alternative forsweetpotato forage production.

Conclusions

The analysis done on s~lected sweetpotatodual-purpose clones indicates that a cuttingfrequency of 90 d during crop growth givesthe best balance between forage and root pro­duction. Harvesting foliage is hard work.Whether farmers are willing to invest in thelabor required to gain maximum forage pro­duction depends on the crop-livestock mix.Studies on grazing cattle are necessary. Con­sidering the wide number of clones available,future selections for consideration as dual-

294 Progrom 6

M. Hermann!, R. Uptmoor2, I. Freire!, and J.L. Montalvo3

Crop Growth and Starch Productivity ofEdible Canna

In addition to taking field surveys in severalcountries, we evaluated plant performance ofcanna in the greenhouse to determine growthvariability and yield characteristics.

(IP Program Report 1995-96 295

The material was grown in a quarantinescreen house in the equatorial Andes nearQuito, Ecuador, at 2,400 m above sea level.Seasonal temperature variation in Quito isminimal; the diurnal temperature in thescreenhouse during the experiment rangedfrom 12 to 2rc. We planted rootedpropagules at a density of 2 plants/m2 in natu­ral soi I of a sandy texture and moderate fer-

Materials and Methods

Drawbacks to canna are its long crop du­ration of 1 yr, which limits the crop's use intight cropping systems. Also, its starch pro­ductivity and plant architecture have not beeninvestigated so far. Therefore, this study aimsto gain a basic understanding of crop growthand starch formation of canna. Recommen­dations for crop management and breedingof this poorly known species wi II be derived.

Greenhouse experimentFor the greenhouse experiment, we used

26 accessions from the international cannacollection held at OP. The accessions wereselected to represent the fu II geograph ic rangeof canna in the Andes and to include diploidand triploid materials. Knowledge of ran­domly amplified polymorphic DNA in thecollection allowed us to identify distinct geno­types for the experiment.

ant and rhizome yields high. Canna is also apromising candidate for agroforestry systemsin tropical mountains where it produces un­der significant shading and on marginal soils.

Canna is an outstandingly versatile androbust crop. It is typically not fertilized andsignificant pests or diseases as well as replantproblems are unknown. Where rice-basedcropping systems predominate, as in Taiwan,Vietnam, and Indonesia, canna is grown onunirrigated uplands, in backyard gardens, orother areas where it does not compete withother food crops. In open (unshaded) plant­ing sites, plant development can be exuber-

Edible canna (Canna edulis Ker-Gawler) is astarchy root crop that is grown sporadicallyin the tropical highlands for food security. Tax­onomists now consider edible canna conspe­cific with ornamental or feral Canna indica.But edible canna's much larger rhizomes,inconspicuous flowers, and high starch con­tent set it apart from C. indica. In its nativeAndean range, as well as in other parts of thedeveloping world, the use of canna for directconsumption is about to disappear, mainlybecause of the long cooking time required tosoften rhizome tissue (>3 h). In Vietnam andsouthern China, however, there has been anew appreciation of canna as a source forstarch in the manufacture of transparentnoodles, a luxury food widely eaten acrossAsia. In Vietnam alone, the canna area is es­timated at 20,000 to 30,000 ha.

1 CIP, Lima, Peru, and Quito, Ecuador.2 Kassel University, Witzenhausen, Germany.3 Universidad Central, Quito, Ecuador.

Canna starch has the largest grains knownand it settles quickly out of a suspension ofgrated tuber tissue. Starch recovery in ruralfactories is therefore high (>80% of totalstarch content). The starch is high in amyloseand functionally similar to mungbean starch,the traditional raw material for transparentnoodles. Canna starch is, however, less ex­pensive to produce.

tility. The crop was irrigated 2 or 3 times/week, but was not fertilized. After 12 mo, weharvested the material and took 4 plants atrandom from each accession for analysis.

Field studyFor the field study, we chose Patate, a

farmer community in the highlands of Ecua­dor (near the equator at 2,350 m), wherecanna is grown commercially for starch. Thehighly drained soils in this area range fromsand to loamy sand, with neutral pH and highnutrient content. Plant available N was 144mg/100 g soil; P, 153 mg/100 g soil; K, 30mg; and Mg, 32 mg. Furrow irrigation wasapplied weekly, but overall soil moisture waslow and most likely represented a growth-lim­iting factor. Mean monthly temperatures were15-17°C with diurnal amplitudes of 10-25°C.During the first 5-6 mo after planting, cannawas intercropped with potatoes and veg­etables. We harvested plots ranging in size

from 10 to 20 m2 in different fields after 6, 8,10, and 12 mo of crop duration. Four repeti­tions were used.

We determined dry matter (DM) at 10SoCand mechanically extracted starch by amethod allowing the recovery of about 90%of total starch. Soluble sol ids were measuredrefractometrically. Leaf area was assessed bya Iinear regression describing the relation ofleaf area to the product of leaf length andwidth. Plant nutrient contents were measuredby standard methods.

Results

Canna's plant architecture is typical for amember of the Zingiberales (Figure 1). Theplant forms a branching rhizome, which inmature plants consists of several segments orgenerations that develop consecutively. Eachsegment carries a shoot, which concludes itsdevelopment with the formation of a termi­nal inflorescence and senesces. Simulta­neously, a new shoot will give rise to a newrhizome segment. Each segment has the ca­pacity to develop sprouts from several buds.The size of the rhizome segments and differ­ent branching modes distinguish rhizomevariabi Iity between accessions (Figure 2).

296 Program 6

Some peculiarities characterize plantgrowth of canna and its measurement. Thedead aboveground plant matter remains at­tached to the plant and can be gathered anddetermined at harvest. Canna is also differ­ent from most other perennial roots in thatthick adventitious roots anchor the rhizomesfirmly in the soil and cause strong pulling re­sistance at harvest.

The youngest rhizome segment (typicallyweighing 50-200 g) is mostly used as thepropagule. It can be stored in the coldestmonths until planting. In equatorial climates,however, only the uppermost apical tip of therhizome, with the emerging shoot attached,is used. That minimizes the use of starchy tis­sue for replanting. Although diploid cultivarsform botanical seeds, these are never used topropagate the crop.

At harvest, after 1 yr of crop duration, to­

tal plant DM in a collection of 26 canna ac-

Figure 1. Ecuadorian accession of edible Canna. Scaleindicates 2 m.

Figure 2. Variability of canna rhizome between genotypes. Scale = 10 em.

Specific leaf weight of canna is compara­tively high; it was the least variable characterin our evaluation (CV=13%). Table 3 givesdata on crop growth, in terms of absolute andrelative OM allocation, for a commercial

The significance of the number of shootsindicated in Table 1 is that it roughly equalsthe number of rhizome segments and thusapproximates the number of propagules thatcan be derived from a plant. In other words,it indicates the multiplication rate, and thisvariable showed the highest variation of thecharacters (means and standard deviation of28 ± 16) under study. Interestingly, the num­ber of stems was inversely correlated to HI,meaning that plants with a large number ofstems (or a higher degree of rhizome ramifi­cation) invested relatively more OM inaboveground plant structures.

(IP Progrom Report 1995-96 297

This means that accessions that are highin soluble solids also tend to have high starchcontents. Starch accounted for only 59 ± 14%of rhizome OM (range 32-88%).

Although the content of physically extract­able starch in the rhizome was low comparedwith other starchy roots--14 ± 4% of rhizomefresh matter (FM)--canna has respectablestarch yields (2.8-14.3 t/ha). As expected, thestarch content of the rhizome was closelycorrelated with rhizome DM content. Surpris­ingly, it was also positively and significantlycorrelated to the content of soluble solids(Table 2), which varied between 5 and 11 °Brix(Table 1).

cessions averaged 24 t/ha; one accessionachieved total OM accumulation of 54 t/haor 5.4 kg/m 2 • Rhizome yields varied consid­erably (17-96 t/ha) with an average of 56 t/ha.Harvest index (HO, the fraction of total OMaccounted for by the rhizomes, was the sec­ond least variable character (56 ± 8%), asindicated by the coefficients of variation (CV).HI was not correlated with rhizome yield(Table 1). On the other hand, the variation oftotal plant OM explained 69% of the varia­tion in rhizome yield (calculated from thecorrelation coefficients shown in Table 2).

Unit Mean Min Max SOb (V (%)

24 8 54 9 3956 17 96 20 357.8 2.8 14.3 3.1 40

56 35 74 8 1533 12 54 11 3219 9 34 7 3523 15 46 7 28

2.5 1.5 5.0 0.9 3528 13 79 16 57

0.44 0.35 0.54 0.06 1324 12 31 4 1814 4 22 4 3059 32 88 14 248.1 5.0 11.0 1.6 20

standard deviation, CV = coefficient of variation.

(ontent Stan:h Stem Harvestof content fraction index

soluble of of rhizome

rhizome total OM fraction

(FM basis) of total OM

-0.320.68** -0.57*'

-0.15 -0.26 -0.10O. 0.66" 0.42*

0.55*'* Significant at P=O.Ol. Only meaningful correlations me shown.

a. dry

Table 2. Pearson's correlation coefficients between growth characteristics of 26 canna accessions, 1996.

Table 1. Variation of growth and yield characteristics at harvest in a collection of 26 canna accessions, 1996.

298 Progrom6

Table 3. Absolute and relotive dry mailer allocation and leaf area index of edible canna according to crop age".

field (the common practice in Ecuadorl, 28%each of Nand P, 3.8% of K, 0.6% of Mg, and62.5% of Ca removed by the rhizomes arereturned to the field. Most of the K (95%) andMg (>99%), however, is lost in the washingwater during starch extraction. Thus, the netnutrient offtake from a canna field would beon the order of 0.54 kg N, 0.53 kg P, 3.11 kgK, 2.47 kg Mg, and 0.37 kg Ca per ton of har­vested rhizomes or per 120-130 kg of ex­tracted dry starch.

(IP PlOglOm Report 1995-96 299

For a primitive crop that has never beensubjected to systematic plant breeding, cannaalso has a remarkably high HI (56 ± 8%).Since this character shows some geneticvariation, it should be possible to breed forincreased HI. We found only a weakly nega-

With rhizome yields averaging 56 t/ha in aninternational germplasm collection, ediblecanna is clearly a highly productive root cropthat compares well with cassava, sweetpotato,and potato. Given an average propagu Ieweight of 50-200 g, and a planting density of20,000 plants/ha, the seed weight of cannaamounts to only 2.5-10% of a typical yield(40 t/ha).

Discussion

Likewise, the fraction of dead plant partsvaries little from 6 to 12 mo, although in ab­solute terms there is a tenfold increase. Thisand the insignificant change in leaf area in­dex from month 8 to month 12 illustrate theperennial nature of canna, which does notreally become senescent at harvest. The rela­tive OM allocation to leaves and stems doesnot show the dramatic changes most othercrops undergo during canopy development.Starch content of the rhizomes, however, in­creased significantly from 5% at 6 mo and7% at 8 mo to 13% at 10 and 12 mo.

The nutrient analysis in rhizomes showedthat per ton of harvested rh izomes, or per 120­130 kg of extracted dry starch, nutrient offtakefrom the field amounted to 0.75 kg N, 0.74kg P, 3.24 kg K, 2.48 kg Mg, and 0.98 kg Ca.But when extraction residue is returned to the

canna starch crop after 6, 8, 10, and 12 moof crop duration. OM buildup in canna isslow. Six months after planting, total OM ac­cumu lation is only 14% of that ach ieved atcommercial harvest 12 mo after planting. Butthe proportion of OM allocated to rhizomeshas reached 41 % at 6 mo and increases dur­ing the second half of crop duration to only49%.

tive but insignificant correlation between HIand total plant OM (Table 2); therefore, se­lection for high total OM in breeding doesnot imply reduced HI as observed in othercrops.

On the basis of our germplasm evaluation,we suggest that canna cultivars for starch ex­ploitation shou ld have large rh izomes. In­deed, predominantly commercial cultivarsexploited for starch have comparatively largerhizomes. Large rhizomes are found in plantswith a low degree of ramification or a lownumber of shoots. These, in turn, are inverselyrelated to HI. Canna breeding should also aimat increasing starch content, which currentlyaccounts for only 59 ± 14% of rhizome OM.All cultivars have significant concentrationsof soluble solids (mostly sugars). If genotypesthat polymerize sugars into starch morereadi Iy were to be found, the starch produc­tivity of canna could be improved by severalpercentage points from a current average of14 ± 4% in rhizome fresh matter.

Another concern for breeders wi II be todevelop cultivars with few adventitious roots.These trap soil and complicate manual har­vest for two reasons. First, soil particles con­taminate the starch or interfere with its ex­traction. Second, the metabolically activeroots seem to contain high concentrations ofoxidases, which are involved in the brown­ing of starch during grating and extraction. InAsia and Latin America, removal of theseroots accounts for most of the worki ng hoursspent during harvest. Simple washing equip­ment, however, such as the revolving drumor the static paddle washers used in smallcassava starch factories in Brazil, is sufficientto remove dirt from canna's adventitiousroots.

Our crop growth data, from plants of com­mercial canna plantations harvested after 6,8, 10, and 12 mo, suggest that the causes forthe initial slow plant development and result­ing long crop duration might be slow leaf areareplication during the juvenile phase. Severallines of evidence support this. Leaf area indi­ces remain low well into the second half ofcrop duration. Although the field crop under

300 Program 6

study had accumulated only 14% of its finalbiomass at 6 mo, OM allocated to the rhi­zomes accounted for 42% of total plant OM.Thus, even before the crop develops signifi­cant leaf area indices, it compromises largeproportions of assimilates in photosyntheti­cally unproductive structures (the rhizomes).

High HI early during development and thepecu Iiar generational development of the rh i­zome, however, provide an opportunity toincrease planting density and to harvest ear­lierthan is currently done. Further studies areneeded to elucidate what effect increasedplanting densities would have on rhizomestarch contents, which seem to remain lowduring the first 8 mo of crop development intraditional systems.

Our data reveal that canna is a nutrient­efficient producer of starch, especially withregard to the environmentally relevant NandP, of which less than 1 kg is removed per tonof harvested rhizomes. A significant fractionof these nutrients can be returned to fields byapplyi ng either fresh or fermented processresidue as fertilizer.

The data also show that major quantitiesof K and Mg are lost in the water used towash out starch from grated pulp. It wouldtherefore seem important that the washingwater be recycled to fields and not discardedinto sewer systems as is currently done. Be­cause the amounts of water used in manu­ally extracting and refining starch are enor­mous (well over 100 L/kg dry starch underAndean conditions), locating extraction plantsabove growing sites and distributing wash­ing water by gravity would be a preliminaryrecommendation.

Conclusions

In conclusion, yield potential, efficient OMpartitioning, nutrient efficiency, and starchquality make canna an interesting starch cropfor resource-poor farmers in the tropical high­lands. However, except for some parts ofSoutheast Asia, where the noodle industry hasfueled demand for canna starch, this crop'spotential is not being recognized. There is

mounting evidence that canna starch couldreplace potato starch because of a high de­gree of functional similarities. Product ex­amples include several types of Asian noodles(for which an increasing share of potato starchis used), certain bakery goods, and thermo­plastics. Many other applications are likelyto be found with appropriate research anddevelopment.

Canna starch has a potentially vast demandif industrial-grade starch were to becomeavailable. Currently, canna starch does notmeet the quality standards required by mostusers. Moreover, canna starch production isat a disadvantage because of the lack of ap­propriate harvesting and extraction equip­ment. Even in developing economies, theexcessive labor costs arising from manualprocessing render canna starch too costly tostay competitive versus inexpensive starchimports. Improvements in the crop's starchproductivity must therefore be accompaniedby the development of improved extractiontechnologies.

Further research is needed to address spe­cific crop constraints, such as the long cropduration; experiments designed to clarify the

effect of planting densities on crop yields andprecocity also seem warranted. Researchaimed at evaluating the feasibility of breed­ing cultivars with improved starch productiv­ity and processing characteristics also de­serves attention. Andean canna germplasmhas recently become available and superiorcultivars can likely be identified for use inareas of narrow genetic variation of this crop,such as in Asia. CIP hopes that interested na­tional programs will join this effort.

Selected Reading

Hermann, M. 1996. Starch noodles fromedible canna (Canna edulisl. In: janick, j.(ed.). Progress in new crops. Am. Soc.Hort. Sci., Alexandria, VA. p. 507-508.

Imai, K., K. Shimabe, K. Tanaka, andT. Kawana. 1994. Studies on matterproduction of edible canna (Cannaedulis Ker.). III. Changes of productionstructure with growth. jap. j. Crop Sci.63(2):345-351 .

Ripperton, j.e. 1927. Carbohydratemetabolism and its relation to growth inthe edible canna. Hawaii Agric.Exp. Stn. Bull. (Washington, DC) No. 56.35 p.

C1PProgromReport1995-96 301

Cross-Program Training Courses1995-1996

Previous Pc:~e :Blank CIP Progrom Report 1995-96 303

A two-week "Workshop on IntegratedWatershed Management in the AndeanEcoregion" was organized by local develop­mental organizations in Cajamarca(ASPADERUC and ADEFOR), with supportfrom CONDESAN and OP. This workshopemphasized theory and practices related tosystems analysis, agroecological zoning,simulation models, and geographic informa­tion systems as tools for identifying alterna­tives for the sustainable development ofAndean agriculture. Two watersheds wereused as case studies, one located on the westside of the Andes (Jequetepeque), and theother an intermontane watershed(Cajamarca). Participants included technicalstaff working in different disciplines (agricul­turists, animal production specialists, ecolo­gists, etc.) as well as policymakers (mayors)from both Cajamarca, Peru, and Carchi Prov­ince in Ecuador.

CIP organized a "Planning Workshop forMountain Forum Activities in Latin America,"sponsored by CON DESAN, to promote thedevelopment of policy actions directed to theequitable and sustainable development ofmountain regions. Participants were from thePro-Sierra Nevada Foundation of Colombia,United Nations Development Programme, theMountain Institute of Huaraz, ASPADERUC,International Conservation, and theUniversidad Nacional Agraria La Molina.

A course on field design, layout, and ad­ministration of field experiments was con­ducted at OP. It covered five main topics:scientific research methods, experimental plotdesign and management, competitive effects,mechanical errors in conducting experiments,and characteristics of the major experimen­tal designs.

Patricio Malagamba

OP's Training Department conducted diverseactivities in 1995-96, mainly involvingcourses, workshops, conferences, and sym­posia, of general coverage of subjects acrossprograms. A symposium on "Current Ap­proaches for Developing Concepts and Prac­tices Related to Agricultural Promotion andDevelopment" was organized in collabora­tion with the Escuela para el Desarrollo, anNCO in Peru and member of CONDESAN,for other national organizations and institu­tions. The symposium's main objective wasto conceptualize and define the baseline re­quired for agricultural development in Peru.Attempts were made to establ ish the relation­ship between promotion policies and prac­tices with principles related to development.It also focused on the need to strengthen in­terdisciplinary interventions that link differ­ent sectors by proposing directions and de­fining concepts and practices involved in ag­ricu Itural development.

A course on "Agroecology and Rural De­velopment" was organized by the ConsorcioLatinoamericano de Agroecologia yDesarrollo, CLADES, and directed to scien­tists and development agents whose activi­ties are related to sustainable developmentof the rural sector. OP sponsored the partici­pation of two national scientists from Cuscoand Cajamarca. PROINPA sponsored fiveparticipants from Bolivia. The course used dis­tance-learning elements and procedures.

A "Production Course on Biological Con­trol in Potato" was held at CIP for staff fromthe national organization responsible for sani­tary control of agricultural products, SENASA.The training program covered biological tech­niques related to the production ofentomopathogens (fungus, virus, and bacte­ria) and parasitoids.

A "Workshop on the Application of CropSimulation Models" was conducted in Cusco,Peru. It was sponsored by CONDESAN incollaboration with the Instituto de Manejo deAguas y Medio Ambiente, Centro de EstudiosBartolome de las Casas, and Plan Meriss Inka.The main objective was to expose participantsto crop simulation models as a methodologi­cal tool for use in more effective decisionmaking with respect to the best use and man­agement of natural resources and to their ap­plication in improving the productivity ofthose crops included in agricultural systemsprevailing in the Andean ecoregion.

304 Training

Sponsored by FAO, IICA, UNEP,CONDESAN, and CIP, a "Regional Confer­ence on Sustainable Agricultural Systems inthe Central Andes" was conducted. The mainobjective of this conference was to evaluatecauses and mechanisms related to social andeconomic deterioration in rural areas as wellas to assess the possible consequences of dif­ferent management strategies. Different strat­egies for the sustainable development of theAndean ecoregion that could be used to gen­erate technical assistance plans in countrieswere analyzed and discussed in detail.

Scientific Publications1995-1996

Abad, Z.G., j.A. Abad, and C. Ochoa. 1995.Historical and scientific evidence that sup­ports the modern theory of the PeruvianAndes as the centre of origin ofPhytophthora infestans. In: Dowley, L.j.,E. Bannon, L.R. Cooke, T. Keane, and E.O'Su lIivan (eds.). Phytophthora infestans150: Proceedings EAPR Pathology Sec­tion, September 1995, Dublin, Ireland.European Association of Potato Research/Boole Press, Dublin, Ireland. p. 239-245.

Anguiz, R.j. and H.A. Mendoza. 1995. Corre­lation between seedling and adult potatoplants for resistance to early blight (Alterna­ria solanO. Fitopatologia 30(2):100-106.

Arbizu, C. 1995. Agroecologia de la achiraen el Peru. Agroenfoque 70:4-5.

ASPADERUC/CONDESAN-CIP/Fondo Peru­Canada. 1995. La Encafiada: Caminos haciala sostenibilidad. Proyecto PIDAE/Asociaci6n para el Desarrollo Rural deCajamarca/Consorcio para el DesarrolloSostenible de la Ecorregi6n Andina-CentroInternacional de la Papa/Fondo ContravalorPeru-Canada, Lima, Peru. 112 p.

Austin, D.F. and Z. Huaman. 1996. A synop­sis of Ipomoea (Convolvulaceae) in theAmericas. Taxon 45(1 ):3-38.

Bamberg, j.B., Z. Huaman, and R. Hoekstra.1995. International cooperation in potatogermplasm. In: R.R. Duncan, D.M. Kral,and M.K. Viney (eds.). Internationalgermplasm transfer: Past and present.Crop. Sci. Soc. of America Special Publi­cation No. 23. p. 177-182.

Blondet, C. and R.L. Duran. 1996. EI impactopotencial de la difusi6n de tecnologiapanificadora de camote en panaderias de

Villa EI Salvador. Documento de Trabajono. 1996-2, C1P, Lima, Peru. 52 p.

Bouis, H.E. and G. Scott. 1996. Demand forhigh value secondary crops in develop­ing countries: The case of potatoes inBangladesh and Pakistan. FCND Discus­sion Papers no. 14. International FoodPolicy Research Institute (IFPRI), FoodConsumption and Nutrition Division(FCND), Washington, D.C., USA. 46 p.

Bouma, j., A. Kuyvenhoven, B.A.M. Bouman,j.e. Luyten, and H.G. Zandstra (eds.).1995. Eco-regional approaches for sus­tainable land use and food production.Proceedings of a symposium held 12-16Dec. 1994, ISNAR, The Hague, Nether­lands. Kluwer Academic Publishers incooperation with the International PotatoCenter, Dordrecht, Netherlands. 596 p.

Bradshaw, j.E., R.L. Wastie, H.E. Stewart, andG.R. Mackay. 1995. Breeding for resis­tance to late blight in Scotland. In: L.j.Dowley, E. Bannon, L.R. Cooke, 1. Keane,and E. O'Sullivan (eds.). Phytophthorainfestans 150. Boole Press, Dublin, Ire­land. p. 246-254.

Cabanilla, L.S. 1996. Sweetpotato in the Phil­ippines: Production, processing, and fu­ture prospects. International Potato Cen­ter, University of the Philippines, Lima,Peru/Manila, Philippines. 100 p.

Cafiizares, C.A. and G.A. Forbes. 1995. Fo­liage resistance to Phytophthora infestans(Mont.) de Bary in the Ecuadorian nationalcollection of Solanum phureja ssp. phurejajuz. & Buk. Potato Res. 38(1 ):3-1 O.

Castillo, R. and M. Hermann.1995. CollectingAndean root and tuber crops (excluding

(IP Progrom Report 1995-96 305

potatoes) in Ecuador. In: Guarino, L.,V. Ramanatha Rao, and R. Reid (eds.). Col­lecting plant genetic diversity: Technicalguidelines. IPGRI!FAO/IUCN/UNEP. CABInternational, Wallingford, UK. p. 639-646.

CIP (International Potato Center). 1995. Vinesto roots, sweetpotato breeding for impact:Recommendations and abstracts. Interna­tional workshop held 1-3 June 1994, Lima,Peru. CIP, Lima, Peru. 46 p.

CIP. 1995. Manual de produccion de papacon semilla sexual. Fasciculos. Lima, Peru.

CIP. 1996. Marchitez bacteriana. Manual deCapacitacion. Lima, Peru.

ClP. 1996. Bacterial wilt manual. Lima, Peru.

CIP. 1996. Manual de manejo degermoplasma de batata 0 camote (Ipo­moea batatas). Fasciculos. Lima, Peru.

CIP. 1996. Accounting for seed potato pro­duction costs: A computer spreadsheet­based management tool. Training Manual.Lima, Peru.

CIP. 1996. La batata en cifras: Un compendiode informacion clave y anal isis para 33importantes paises productores de batata,produccion, uso, consumo yalimentacionanimal. Lima, Peru. v p.

CIP. 1996. Late blight: A global initiative.Lima, Peru. 21 p.

CIP. 1996. Major potato diseases, insects, andnematodes. Lima, Peru. 111 p.

CIP. 1996. Principales enfermedades,nematodos e insectos de la papa. Lima,Peru. 111 p.

CIP. 1996. Sweetpotato facts: A compendiumof key figures and analysis for 33 impor­tant sweetpotato-producing countries,production, use, consumption, feed use.Lima, Peru. v p.

306 Publicotions

CIP/COTESU (Centro Internacional de la PapalCooperaci6n Tecnica Suiza). 1995. ProgramaColaborativo Biodiversidad de Rakes yTuberculos Andinos. Memorias 1993-1994.C1P/COTESU, Lima, Peru. 322 p.

CON DESAN (Consortium for the SustainableDevelopment of the Andean Ecoregion).1995. A post-UNCED progress report onAndean natural resource research. CIP,Lima, Peru. 16 p.

Cottrell, J.E., CM. Duffus, L. Patterson, and G.R.Mackay. 1995. Properties of potato starch:Effects of genotype and growing conditions.Phytochemistry 40(4):1057-1 064.

Crissman, C. and A. Hibon. 1996. Establish­ing seed potato prices: Concepts, proce­dures and implications for research andtraining. Social Science Department.Working Paper Series no. 1996-1, CIP,Lima, Peru. 24 p.

Chavez, R., M. Upadhya, H. Mendoza,J. Espinoza, R. Cabello, P. Siles, G. Bolio,T. Melendez, J. Eyzaguirre, C. Maquera,E. Guevara, K. Monasterio. 1996. Nuevashipotesis y avances de seleccion en elmejoramiento genetico de papa y camotepara adaptacion a suelos aridos y salinos.Rev. Consejo de Investigacion (COIN),Ciencia y Desarrollo, Univ. Jorge BasadreGrohmann (Peru). p. 32-54.

Chujoy, E. 1995. Root crops germplasm re­search in Vietnam. ClP/National Instituteof Agricultural Sciences (lNSA)/lnterna­tional Development Research Centre(lDRC), Manila, Philippines. 62 p.

Dayal, T.R., G.J. Scott, G.T. Kurup, andC. Balagopalan (eds.). 1996. Sweetpotatoin South Asia: Postharvest handling, pro­cessing, storage, and use (Proceedings ofa workshop). Trivandrum, India, 9-13 Sept.1991. Central Tuber Crops Research In­stitute (CTCRI), ClP, Lima, Peru. 137 p.

Dfaz, J., P. Schmiediche, and D.F. Austin.1996. Polygon of crossability betweeneleven species of Ipomoea: Section

Batatas (Convolvulaceae). Euphytica88(3):189-200.

Engels, C, j. Schwenkel, R. EI Bedewy, andB. Sattelmacher. 1995. Effect of the de­velopment stage of potato seedlings onrecovery after transplanting to the fieldand on tuber yield. j. Agric. Sci.124(2):213-218.

Estrada, R.D. 1996. Analisis ex post de lainfluencia de algunas variables macro­econ6micas sobre la competitividadagropecuaria, equidad y conservaci6n derecursos. In: Rivera, B. and R. Aubad(eds.). IESA America Latina 1995: EIenfoque de sistemas de producci6n y laincorporaci6n de criterios de politica:Memorias 2. Simposio Latinoamericanosobre Investigaci6n y Extensi6n enSistemas Agropecuarios. Santa Fe deBogota, Colombia, 7-9 Nov. 1995.Corporaci6n Colombiana de Investigaci6nAgropecuaria (CORPOICA), Bogota, Co­lombia. p. 219-230.

Fano, H., O. Ortiz, and T. Walker. 1996. Peru:Inter-institutional cooperation for IPM. In:Thrupp, L.A. (ed.). New partnerships forsustainable agriculture. World ResourcesInstitute (WRI), Washington, D.C, USA.p.85-98.

FAO (Oficina Regional para America Latinay el Caribe). 1995. Manual tecnico deproducci6n de papa a partir de semillasexual: Curso audiovisual. FAO/CentroInternacional de la Papa/lnstituto deInvestigaciones Agropecuarias (lNIA),Santiago, Chile. 72 p.

FAO/OP (Food and Agriculture Organization/International Potato Center). 1995. Potatoesin the 1990s: Situation and prospects of theworld potato economy.! La papa en ladecada de 1990: Situaci6n y perspectivasde la economfa de la papa a nivel mundial./La pomme de terre dans les annees 90: Situ­ation actuelle et perspectives de I'economiemondiale de la pomme de terre. Rome, Italy.39 p., 50 p., 44 p.

French, E.R. and G.R. Mackay (eds.l. 1996.Enhancing the global late blight network:Report of the project design meeting onthe Global Initiative on Late Blight. OP,Lima, Peru. 43 p.

Fuentes, S., MA Mayo, CA. jolly, M. Querci,and L.F. Salazar. 1996. A novel luteovirusfrom sweet potato, sweet potato leafspeckling virus. Ann. Appl. BioI.128(3):491-504.

Gibson, R.W., R.O.M. Mwanga, S. Kasule,S. Fuentes, and E.E. Carey. 1996. Sweetpotato feathery mottle and other virusesin Uganda. In: Proceedings ofthe regionalsweetpotato workshop. Commission of theEuropean Union, Technical AgriculturalCenter (TAC), Libreville, Gabon. p. 87-90.

Gitomer, CS. 1996. Potato and sweetpotatoin China: Systems, constraints, and poten­tial. OP/ Chinese Academy of AgriculturalSciences (CAAS), Lima, Peru. 183 p.

Golmirzaie, A.M. and L.F. Salazar. 1996. Ap­plication of biotechnology for conserva­tion and uti Iization of Andean root andtuber crops and biosafety guidelines. Af­rican Crop Sci. j. 3(3):341-344.

Gregory, P. 1996. Global program to developlate blight resistant potato cultivars.CGIAR News 3(3):1.

Gutarra, L., T. lcochea, and E.R. French. 1995.Etiologfa de pudriciones bacterianas detuberculos de ulluco (Ullucus tuberosusCaldas). Fitopatologfa 30(2):92-95.

Hagenimana, v" R.E. Simard, and L.P. Vezina.1996. Method for the hydrolysis of starchymaterials by sweetpotato endogenousamylases. U.S. Patent no. 5,525,154. june11, 1996. 11 p.

Hardy, B. and E.R. French (eds.). 1995. Inte­grated management of bacterial wilt: Pro­ceedings of an international workshopheld in New Delhi, India, 11-16 Oct.1993. International Potato Center (CIP)/

(lP Progrom Report 1995-96 307

Indian Council of Agricultural Research,Lima, Peru. 196 p.

Hardy, B., P. Malagamba, and C. Martin (eds.).1995. True potato seed in the Middle Eastand Africa: Proceedings of an internationalworkshop held in Cairo, Egypt, 9-15 Apr.1994. International Potato Center (CIP),Lima, Peru. 97 p.

Hijmans, R.j. and M.K. van Ittersum. 1996.Aggregation of spatial units in linear pro­gramming models to explore land useoptions. Neth. J. Agric. Sci. 44: 145-162.

Hoekstra, R. and Z. Huaman. 1995. ClP pro­motes wider use of root and tuber crops.PROPHYTA Annual 1995. p. 102-103.

Holle, M. 1996. La biodiversidad es una delas bases del desarrollo sustentable. In:Rivera, B. and R. Aubad (eds,). p. 77-78. *

Huaman, Z. 1995. Tecnicas citol6gicas paradeterminar el numero cromos6mico y lafertilidad de las papas. Gufa de Investigaci6nCIP no. 10. CIP, Lima, Peru. 18 p.

Huaman, Z., F. de la Puente, and C. Arbizu.1995. Collecting vegetatively propagatedcrops (especially roots and tubers). In:Guarino, L., V. Ramanatha Rao, andR. Reid (eds.l. Collecting plant geneticdiversity: Technical guidelines. IPGRI!FAO/IUCN/UNEP. CAB International,Wallingford, UK. p. 457-466.

Instituto Boliviano de Tecnologfa Agropecuaria(IBTA). 1995. Primera reuni6n nacional derecursos geneticos de papa, rakes ytuberculos andinos: Memorias.Cochabamba, Bolivia, 7-10 Feb. 1994.IPGRI/CIP/IICA/PROCISUR/COTESU/PNUD, Cochabamba, Bolivia. 341 p.

jacobsen, S.-E., j. Hill, and O. Stollen. 1996.Stability of quantitative traits in quinoa(Chenopodium quinoa). Theor. App!.Genet. 93:110-116.

Khatana, V.S., M.D. Upadhya, A. Chilver, andc.c. Crissman. 1996. Economic impact of

308 Publicotions

true potato seed on potato production ineastern and northeastern India. ClP, Lima,Peru. 19 p.

Korva, J.T. and G.A. Forbes. 1995. A simplenon-destructive technique for healthy anddiseased leaf area assessment of potatoplants. Potato Res. 38(1):31-37.

Kreul, W. and B. Trognitz.1995. Forschungss­chwerpunkte des Internationalen KartoffelForschungszentrums - CIP - in Peru.Entwicklung + Landlicher Raum(Germany) 29(5):30-32.

Landeo, J.A., M. Gastelo, H. Pinedo, andF. Flores. 1995. Breeding for horizontalresistance to late blight in potato free ofR genes. In: Dowley, L.j., E. Bannon, L.R.Cooke, T. Keane, and E. O'Sullivan (eds.).Phytophthora infestans 150: ProceedingsEAPR Pathology Section, September 1995,Dublin, Ireland. European Association ofPotato Research/Boole Press, Dublin,Ireland. p. 268-274.

Martin, c., P. Demo, D. Njualem, T. Gass,and C. Ntonifor. 1995. Late blight resis­tant varieties for Cameroon. Am. Potato j.72(9):513-522.

Martin, c., P. Demo, T. Gass, V. Fondong, andJ. Koi. 1995. Development of a seed pro­duction system from in vitro in Cameroon:Experiences from the first two years. Am.Potato J. 72(5):299-302.

Martinez, c.A., C. Guerrero, and U. Moreno.1995. Diurnal fluctuations of carbon ex­change rate, proline content, and osmoticpotential in two water-stressed potato hy­brids. Rev. Bras. Fisiol. Veg. 7(1 ):27-33.

Maz6n Ortiz, N., R. Castillo Torres,M. Hermann, and P. Espinosa. 1996.La zanahoria blanca 0 arracacha(Arracacia xanthorrhiza Bancroft) enEcuador. Publicaci6n Miscelanea no.67. Instituto Nacional Auton6mo deInvestigaci6n Agropecuaria (INIAP)/Dept.de Recursos Fitogeneticos y Biotecnologia(DENAREF)/CIP, Quito, Ecuador. 41 p.

'See the entry for Estrada, R.D., for details on this publication.

Mendoza, H.A, E.j. Mihovilovich, andF. Saguma. 1996. Identification of triplex(YYYy) potato virus Y (PVY) immuneprogenitors derived from Solanumtuberosum ssp. andigena. Am. Potato j.73(1 ):13-19.

Mujica B., E. and j.L. Rueda S. 1996. EIdesarrollo sostenible de montaiias enAmerica Latina: Actas de la segundaconsulta regional intergubernamentalsobre el desarrollo sostenible demontanas. CONDESAN/CiP/FAO, Lima,Peru. 318 p.

Pallais, N. 1995. High temperature and lowmoisture reduce the storage requirementof freshly harvested true potato seed. j.Am. Soc. Hart. Sci. 120(4):699-702.

Pallais, N. 1995. Storage factors control ger­mination and seedling establishment offreshly harvested true potato seed. Am. Po­tato j. 2(7):427-436.

Pallais, N., j. Santos-Rojas, and R. Falcon.1996. Storage temperature affects sexualpotato seed dormancy. HortScience31(1):99-101.

Prain, G.D., I.G. Mok, T. Sawor, P. Chadikun,E. Atmodjo, and E. Relwaty Sitmorang.1995. Interdisciplinary collecting of Ipo­moea batatas germplasm and associatedindigenous knowledge in Irian jaya. In:Guarino, L., V. Ramanatha Rao, andR. Reid (eds.). Collecting plant geneticdiversity: Technical guidelines. IPGRI/FAO/IUCN/UNEP, CAB International,Wallingford, UK. p. 695-711.

Programa Colaborativo Biodiversidad deRakes y Tuberculos Andinos. 1996.Memorias 1994-1995. ClP/CooperacionTecnica Suiza (COTESU)/Consorcio parael Desarrollo Sostenible de la EcorregionAndina (CONDESAN), Lima, Peru. 370 p.

Querci, M., D.e. Baulcombe, R.W. Goldbach,and L. F. Salazar. 1995. Analysis of the re­sistance-breaking determinants of potatovirus X (PVX) strain HB on different po-

tato genotypes expressing extreme resis­tance to PYX. Phytopathology 85(9):1 003­1010.

Quiroga, j., G. Watson, H. Cardozo,O. Navia, R. Casso, and R. Andrew. 1995.Diagnostico interdisciplinario del cultivode la papa en la zona de Iscayachi, Tarija(campana 1991-1992). Documento deTrabajo no. 1/95. Instituto Boliviano deTecnologfa Agropecuaria (IBTA)/ Programade Investigacion de la Papa (PROINPA),Cochabamba, Bolivia. 35 p.

Quiros, e.F., A. Epperson, j. Hu, and M. Holle.1996. Physiological studies and determi­nation of chromosome number in maca,Lepidium meyenii (Brassicaceae). Econ.Bot. 50(2):216-223.

Quiroz, R., e. Leon Velarde, B. Arce, andD. Genin. 1996. Resultados de ensayos enganaderfa con modelos de simulacion. In:Rivera, B. and R. Aubad (eds.). p. 113-123.*

Quiroz, R.A., R.D. Estrada, e. Leon Velarde,and H.G. Zandstra. 1995. Facing the chal­lenge of the Andean zone: The role ofmodeling in developing sustainable man­agement of natural resources. In: Bouma,j., A. Kuyvenhoven, B.A.M. Bouman, j.e.Luyten, and H.G. Zandstra. Eco-regionalapproaches for sustainable land use andfood production: Proceedings of a sym­posium held 12-16 Dec. 1994, ISNAR,The Hague, Netherlands. Kluwer Aca­demic Publishers in cooperation with theInternational Potato Center, Dordrecht,Netherlands. p. 13-31.

Rivera, j.j. and R.D. Estrada. 1996.Cuantificacion ex ante del intercambio en­tre equidad, productividad y sostenibilidadpara el diseno de alternativas tecnologicas:EI caso del cultivo de arracacha en Colom­bia. In: Rivera, B. and R. Aubad (eds.).p.101-112.*

Rodriguez Quijano, P. 1996. La papa y eldesarrollo econ6mico en Colombia. ClP/Corparaci6n Colombiana de InvestigacionAgropecuaria, Lima, Peru. 114 p.

(IP Program Report 1995-96 309

Rousselle-Bourgeois, F. and S. Priou. 1995.Screening tuber-bearing Solanum spp. forresistance to soft rot caused by Erwiniacarotovora ssp. atroseptica (van Hall) Dye.Potato Res. 38(2):111-118.

Salazar, L.F. 1995. Los virus de la papa y sucontrol. OP, Lima, Peru. 226 p.

Salazar, L.F. 1996. Aplicaci6n de lamicroscopia electr6nica en la virologiavegetal. In: Castillo de Maruenda, E.,N. Rojas Moran, and A. L6pez Milia (eds.).Microscopia electr6nica en el Peru.Consejo Nacional de Ciencia y Tecnologia(CONCYTEC), Lima, Peru. p. 43-48.

Salazar, L.F. 1996. Potato viruses and theircontrol. Lima, Peru. 214 p.

Salazar, L.F., M. Querci, I. Bartolini, andV. Lazarte. 1995. Aphid transmission of po­tato spindle tuber viroid assisted by potatoleafroll virus. Fitopatologia 30(1 ):56-58.

Sanchez, I., M. Milian, A. Morales, and F. dela Puente. 1995. Prospecci6n de recursosgeneticos de raices y tuberculos tropicalesen Cuba en 1991. Cultivos Tropicales16(1 ):84-87.

Sanchez, I., M. Milian, A. Morales, and F. dela Puente. 1995. Prospecci6n de recursosgeneticos de raices y tuberculos tropicalesen Cuba en 1992. Cultivos Tropicales16(1 ):88-95.

Scott, G.j. (ed.). 1995. Prices, products, andpeople: Analyzing agricultural markets indeveloping countries. Lynne Rienner Pub­lishers in cooperation with the Interna­tional Potato Center (OP), Boulder, Colo­rado, USA. 493 p.

Scott, G.j. 1996. Paradoxes and projectionsfor potatoes in the 1990s. Entwicklung +Landlicher Raum. 30(3):20-22.

Seminario Cunya, j. and A. Seminario Cunya.1995. Colecci6n regional degermoplasma de raices andinas.Universidad Nacional de Cajamarca

310 Publicotions

(UNC)/Programa Biodiversidad de Rakesy Tuberculos Andinos Convenio C1P­COTESU, Cajamarca, Peru. 32 p.

Smit, N.E.j.M. and L.O. Matengo. 1995. Farm­ers' cultural practices and their effects onpest control in sweetpotato in SouthNyanza, Kenya. Int. j. Pest Manage.41 (1 ):2-7.

Thiele, G., A. Devaux, and C. Soria. 1996.Innovaci6n tecnol6gica en la papa: De laoferta de tecnologia al impacto macro­econ6mico. In: Rivera, B. and R. Aubad(eds.). p. 79-88.*

Thro, A.M., R.N. Beachy, M. Bonierbale,C. Fauquet, G. Henry, G.G. Henshaw,M.A. Hughes, K. Kawano, Cj.j.M.Raemakers, W. Roca, C. Schopke, N. Tay­lor, and R.G.F. Visser. 1996. Internationalresearch on biochemistry of cassava (tapi­oca, Manihot esculenta Crantz) and its rel­evance to Southeast Asian economies: ACassava Biotechnology Network review.Asian j. Trop. BioI. 2(1):1-30.

Torres, H., M.A. Pacheco, and E.R. French.1995. Resistance of potato to powderyscab (Spongospora subterranea) underAndean field conditions. Am. Potato j.72(6):355-363.

Trognitz, B.R. 1995. Analysis of pollen tubegrowth in situ to investigate self-incom­pati bi Iity in the wi Id potato Solanumcommersonii. Euphytica 86(2): 149-156.

Trognitz, B.R. 1995. Female fertility of potato(Solanum tuberosum ssp. tuberosum)dihaploids. Euphytica 81 (1 ):27-33.

Upadhya, M. 1996. True potato seed tech­nology to fight potato blight in develop­ing countries. Diversity 12(3):67-68.

Upadhya, M.D., B. Hardy, P.c. Gaur, andS.G. Ilangantileke. 1996. Production andutilization of true potato seed in Asia. CIPIIndian Council of Agricultural Research,Lima, Peru. 233 p.

Valdivia, R., E. Huallpa, V. Choquehuanca,and M. Holle. 1996. Monitoring potatoand Oxalis varieties in mixtures grown onfarm family fields in the Titicaca Lake ba­sin, Peru, 1990-95. In: Eyzaguirre, P. andM. Iwanaga (eds.). Participatory plantbreeding: Proceedings of a workshop.Wageningen, Netherlands, 26-29 july1995. International Plant Genetic Re­sources Institute (IPGRI), Rome, Italy.p. 144-150.

Valkonen, j.P.T., M. Orrillo, S.A. Slack,R.L. Plaisted, and K.N. Watanabe. 1995.Resistance to viruses in F] hybrids pro­duced by direct crossing between diploidSolanum series Tuberosa and diploid S.brevidens (series Etuberosa) using S.phureja for rescue pollination. PlantBreed. 114:421-426.

Van den Berg, j.H., E.E. Ewing, R.L. Plaisted,S. McMurry, and M.W. Bonierbale. 1996.QTL analysis of potato tuber dormancy.Theor. App!. Genet. 93(2):317-324.

Van den Berg, j.H., E.E. Ewing, R.L. Plaisted,S. McMurry, and M.W. Bonierbale. 1996.QTL analysis of potato tuberization. Theor.App!. Genet. 93(3):307-316.

Velit Tamanaja, E. 1996. Identificaci6n devirus en papa (Solanum tuberosum). In:Castillo de Maruenda, E., N. Rojas Moran,and A. L6pez Milia (eds.l. Microscopfaelectr6nica en el Peru. Consejo Nacionalde Ciencia y Tecnologfa (CONCYTEC),Lima, Peru. p. 75-80.

Walker, T.S. and c.c. Crissman. 1996. Casestudies of the economic impact of CIP-re­lated technology. Lima, Peru. 157 p.

Walker, T.S. and c.c. Crissman. 1996.Estudios de casos del impacto econ6micode la tecnologfa relacionada con el ClPen el Peru. Lima, Peru. 32 p.

Watanabe, K., M. Orrillo, and A.M. Golmirzaie.1995. Potato germplasm enhancement forresistance to biotic stresses at CIP: Conven­tional and biotechnology-assisted ap-

proaches using a wide range of Solanumspecies. Euphytica 85:457-464.

Watanabe, K.N., M. Orrillo, A.M. Golmirzaie,S. Perez, j. Crusado, and j.A. Watanabe.1996. Generation of pest resistance: Dip­loid potato germplasm with short day ad­aptation from diverse genetic stocks.Breeding Sci. 46:329-336.

Watanabe, K.N., M. Orrillo, S. Vega, j.P.T.Val konen, E. Pehu, A. Hurtado, andS.D. Tanksley. 1995. Overcoming cross­ing barriers between nontuber-bearingand tuber-bearing Solanum species: To­wards potato germplasm enhancementwith a broad spectrum of solanaceousgenetic resources. Genome 38:27-35.

Watanabe, K.N., M. Orrillo, S. Vega,M. Iwanaga, R. Ortiz, R. Freyre, G. Yerk,S.j. Peloquin, and K. Ishiki. 1995. Selec­tion of diploid potato clones from dip­loid (haploid X wild species) F] hybridfamilies for short day conditions. Breed.Sci. 45:341-347.

Watanabe, K.N .. j.P.T. Valkonen, and P. Gre­gory. 1995. Use of plant biotechnologytools in plant protection, genetic resourcesmanagement and crop genetic improve­ment: An interdisciplinary approach withpotatoes at the International Potato Cen­ter. In: Altman, O.K. and K. N. Watanabe(eds.). Plant biotechnology transfer to de­veloping countries. Academic Press Inc.,Texas. p. 179-188.

Wheatley, c., G.j. Scott, R. Best, andS. Wiersema. 1995. Adding value to rootand tuber crops: A manual on productdevelopment. Centro Internacional deAgricultura Tropical (ClAT), Cali, Colom­bia. 166 p.

Yencho, G.c., M.W. Bonierbale, W.M. Tingey,R.L. Plaisted, and S.D. Tanksley. 1996.Molecular markers locate genes for resis­tance to the Colorado potato beetle(Leptinotarsa decemlineata) in hybridSolanum tuberosum x S. berthaultii po­tato progenies. Entomo!. Exp. App!.81 :141 -154.

CIP Progrom Report 1995-96 311

Zandstra, H.G. 1996. The CGIAR responseto new challenges in agroenvironmentalresearch in developing countries. In:Rivera, B. and R. Aubad (eds.). p. 335-342.*

Zandstra, H.G. 1996. Twenty-five years of in­ternational potato research, a retrospec-

312 Publicotions

tive and forward look. Potato Res.39(4):395-401.

Zhang, D., W.W. Collins, and M. Andrade.1995. Estimation of genetic variance ofstarch digestibility in sweetpotato.HortScience 30(2):348-349.

CIP Board Members 1995-1996

Dr. Lindsay Innes' (Chairperson)Deputy DirectorScottish Crop Research InstituteDundee, Scotland

Mrs. Martha ter Kuile (Chairperson)Ontario, Canada

Dr. Hubert ZandstraDirector GeneralInternational Potato CenterLima, Peru

Dr. Setijati SastrapradjaIndonesian Institute of SciencesNational Centre for Research inBiotechnologyBogor, Indonesia

Dr. K. L. Chadha (Vice Chair)Deputy Director General (Hort.)Indian Council of Agricultural ResearchNew Delhi, India

Dr. Klaus RavenUniversidad Nacional AgrariaLa Molina,Lima, Peru

Dr. Durward BatemanDean, College of Agricultural and LifeSciencesNorth Carolina State UniversityRaleigh, N.C., USA

Dr. Toshihiro Kajiwara'Director, japan PlantProtection AssociationTokyo, japan

1 Left in 1995.2 Joined in 1996.

Dr. Moise MensahCotonou, Benin

Dr. Lieselotte SchildeInstitute of Plant BiochemistryUniversity of TubingenTubingen, Germany

Dr. Koenraad VerhoeffWageningen, The Netherlands

Dr. Chukichi Kaneda2

Association for International Coopera­tion of Agriculture & ForestryTokyo, japan

Dr. Vo-Tong Xuan2

Vice Rector & DirectorMekong Delta Farming Systems R&DInstituteUniversity of CanthoCantho, Vietnam

Dr. Adrian Fajardo-ChristenMinisterio de la PresidenciaLima, Peru

Dr. Alfonso Cerrate'Executive DirectorInstituto Nacional de Investigaci6nAgrariaLima, Peru

(IP Program Report 1995-96 31 3

CIP Staff in 1995-1996

Directors

Hubert Zandstra, PhD, Director GeneralJose Valle-Riestra, PhD, Deputy Director Gen­

eral for Finance and AdministrationPeter Gregory, PhD, Deputy Director Gen­

eral for ResearchRoger Cortbaoui, PhD, Director for Interna­

tional CooperationEdward French, PhD, Associate Director for

Research (since May 1996)George Mackay, MS, Director of Genetic Re­

sources4

Program Leaders

Production SystemsThomas S. Walker, PhD

Germplasm Management and EnhancementAli Golmirzaie, PhD

Disease ManagementEdward French, PhD (until April 1996)Luis F. Salazar, PhD (since May 1996)

Integrated Pest ManagementFausto Cisneros, PhD

Propagation, Crop ManagementMahesh Upadhya, PhD

Postharvest Management, MarketingGregory J. Scott, PhD

1 Staff who joi ned in 19952 Staff who joined in 19963 Staff who left in 19954 Staff who left in 19965 Staff funded by special projects6 Project leader7 Died in 1995

314 Stoff

InternationalCooperation

(country) =post location, but activity regionalin scope

country =post location

Latin America and the Caribbean (LAC)Fernando Ezeta, PhD, Regional Representative

(Peru)

liaison Office-EcuadorCharles Crissman, PhD

Sub-Saharan Africa (SSA)Peter Ewell, PhD, Regional Representative

(Kenya)

liaison Office-NigeriaHumberto Mendoza, PhD6

Middle East and North Africa (MENA)Aziz Lagnaoui, PhD, Regional Representative

(Tunisia) (from June 1995)Carlos Martin, PhD, Regional Representative

(Tunisia) (until June 1995)

liaison Office-EgyptRamzy EI-Bedewy, PhD

South and West Asia (SWA)Sarathchandra Ilangantileke, PhD, Regional

Representative (India)

East and Southeast Asia and the Pacific(ESEAP)

Peter Schmiediche, PhD, Regional Represen­tative (Indonesia)

liaison Office-People's Republic of ChinaSong Bo Fu, PhD

liaison Office-PhilippinesGordon Prain, PhD

Internationally Recruited Staff

Departments

Breeding and GeneticsJuan Landeo, PhD, Acting Head of Depart-

ment, Breeder6

Edward Carey, PhD, Breeder (Kenya)6

Enrique Chujoy, PhD, Geneticist Undonesia)

Haile M. Kidane-Mariam, PhD, Breeder(Kenya)6

Humberto Mendoza, PhD, Geneticist (Nige­ria) 6

II Gin Mok, PhD, Breeder (Indonesia)

Genetic ResourcesAli Golmirzaie, PhD, Geneticist, Head of

Department6

Carlos Arbizu, PhD, ARTC ConsultantSFermin de la Puente, PhD, Germplasm Col­

lector4

Marc Ghislain, PhD, Molecular Biologist"Michael Hermann, PhD, Andean Crop Spe­

cialist, Ecuador

Z6simo Huaman, PhD, Germplasm Curator6

Koshun Ishiki, PhD, Associate Expert, Ecua-dor4's

Carlos Ochoa, MS, Taxonomist, ConsultantPeter Schmiediche, PhD, Breeder (Indonesia)Bodo Trognitz, PhD, Geneticist6

Kazuo Watanabe, PhD, Cytogeneticist (USA)4

Dapeng Zhang, PhD, Breeder"

Nematology and EntomologyFausto Cisneros, PhD, Entomologist, Head of

Department6

Ann Braun, PhD, Ecologist Undonesia)6

Aziz Lagnaoui, PhD, Entomologist (Tunisia)

Nicole Smit, MS, Associate Expert, UgandaS

Jean Louis Zeddam, PhD, Entomovirologist

PathologyLuis Salazar, PhD, Virologist, Head of Depart­

ment6

John Elphinstone, PhD, Adjunct Scientist, UK

Gregory A. Forbes, PhD, Plant Pathologist(Ecuador)6

Edward R. French, PhD, Bacteriologist6

Teresa Icochea, PhD, Pathologist, Consultant6

Upali Jayasinghe, PhD, Virologist (Phi/ip-pines)6

Rebecca Nelson, PhD, Molecular Pathologist2

Pedro Oyarzun, PhD, Mycologist (Ecuador)S

Sylvie Priou, PhD, BacteriologistSMaddalena Querci, PhD, Molecular Virologist6

Lod J. Turkensteen, PhD, Adjunct Scientist,Netherlands

PhysiologyMahesh Upadhya, PhD, Breeder, Head of

Department6

Catherine Brabet, PhD, Associate Expert2

Ramzy EI-Bedewy, PhD, Breeder, EgyptVital Hagenimana, PhD, Food Scientist

(Kenya)S

Oscar Hidalgo, PhD, Senior Seed Specialist6

Sarathchandra Ilangantileke, PhD,Postharvest Specialist (lndia)6

Jukka Korva, MS, Fellowship Agronomist,Ecuador4,s

Noel Pallais, PhD, Physiologist6

Marian Van Hal, MS, Associate Expert1

Christopher Wheatley, PhD, Postharvest Spe-cialist Undonesia)6

Social ScienceThomas Walker, PhD, Economist, Head of

Department6

Johan Brons, MS, Associate Expert (Philip­pines)2-s

Alwyn Chilver, MS, Associate Expert, Indo-nesiaS

Charles Crissman, PhD, Economist (Ecuador)6

Peter Ewell, PhD, Economist (Kenya)6

Robert Jan Hijmans, MS, Associate ExpertSJan Low, PhD, Economist (Kenya)4,S

Dai Peters, PhD, Rural Sociologist Undone­sia)2

Gordon Prain, PhD, Anthropologist (Philip­pines)6

Gregory Scott, PhD, Economist6

Julia Wright, MS, Associate Expert1,4

TrainingPatricio Malagamba, PhD, Head of Depart­

ment

CommunicationsEdward Sulzberger, MS, Acting Head of Unit

(from Sept. 1996)Bill Hardy, PhD, English and Spanish Writer!

Editor, Acting Head of Unit (until Sept.1996)

(IP Progrom Report 1995-96 31 5

Michel L.Smith, Journalist, Head of Depart­ment4

Information TechnologyAnthony Collins, Heads

Directors' Offices

Office of the Director GeneralEdward Sulzberger, MS, Senior Adviser

Office of the Deputy Director General forResearch

Jose Luis Rueda, PhD, Coordinator, AndeanNatural Resources

Office of the Deputy Director General forFinance and Administration

William A. Hamann, BS, Assistant to theDDGF&N

Special Country Projects

FORTI PAPA, EcuadorAlberic Hibon, PhD, Economist, Team

Leader4,sCorinne Fankhauser, MS, Associate Expert1

PROINPA, BoliviaAndre Devaux, PhD, Seed Specialist, Team

LeadersEnrique Fernandez-Northcote, PhD, Virolo­

gistSJavier Franco, PhD, NematologistS,6Graham P. Thiele, PhD, Technology Transfer

SpecialistS

UgandaNicole Smit, MS, Associate ExpertS

Consortium CONDESANRobert Jan Hijmans, Ir, Associate ExpertSMiguel Holle, PhD, Biodiversity of Andean

CropsS,6Carlos Leon-Velarde, PhD, Animal Produc­

tion Systemss

Osvaldo Paladines, PhD, Andean Pastures(Ecuador)S

Roberto Quiroz, PhD, Land Use Systems Spe­cialistS

316 Stoff

Joint Appointments with Other InstitutionsWalter Bowen, PhD, Nutrient Cycling Spe­

cialist, IFOCRuben Daria Estrada, MS, Natural Resources

Economics (Colombia), CIArs

Networks

ASPRADEufemio 1. Rasco Jr., PhD, Coordinator (Phil­

ippines)S

UPWARDGordon Prain, PhD, Coordinator (Philippines)

Controller's OfficeCarlos Nino-Neira, CPA, Controller

Office of the Executive OfficerCesar Vittorelli, Ing. Agr., Acting Executive

Officer

Nationally Recruited Staff

Departments

Breeding and GeneticsWalter Amoros, MS, AgronomistMiguel Ato, Food Industries Specialist3

Raul Anguiz, MS, Agronomist4

Luis Calua, MS, Agronomist4

T.R. Dayal, PhD, Associate Expert Undia)Luis Diaz, MS, AgronomistJorge Espinoza, MS, AgronomistManuel Gastelo, MS, AgronomistShimon Gichuki, MSc, Breeder, KenyaHugo Gonzales, Ing. Agr., Agronomist, ChilePamela Jean Lopez, MS, Breeder, PhilippinesElisa Mihovilovich, MS, BiologistDaniel Reynoso, MS, AgronomistK.C. Thakur, PhD, Breeder, India

Genetic ResourcesCesar A. Aguilar, Agronomist, HuancayoVictor H. Asmat, BiologistMi Iciades A. Baltazar, Agronomist,

San Ramon 3

Jorge Benavides, BiologistFausto Buitron, Agronomist4

Patricia G. Cipriani, BiologistSWalberto M. Eslava, AgronomistRene A. Gomez, AgronomistMarfa del Rosario Herrera, BiologistAna M. Hurtado, BiologistSLuis H. Nopo, BiologistSMarfa Gisella Orjeda, PhD, Biologist4

Matilde Orrillo, BiologistAna Luz Panta, BiologistFlor de Marfa Rodrfguez, BiologistSAlberto Salas, AgronomistRoxana Salinas, Agronomist4

Jorge Tenorio, BiologistJudith Toledo, Biologist2

Fanny Vargas, Agronomist

Nematology and EntomologyJesus Alcazar, MS, Assoc. Agronomist6

Juan Cabrera, MS, Agronomist2

Manuel Canto, PhD, NematologistS,6

Veronica Canedo, BiologistJavier Carhuamaca, Ing. Agr. s

Wilfredo Catalan, Ing. Agr. 4

Victor Cerna, Ing. Agr.s

Roberto Delgado de la Flor, Agronomist'Oder Fabian, Ing. Agr. 4

Erwin Guevara, Ing. Agr., Agronomist6

Rocio Haddad, Biologist3

Angela Matos, Ing. Agr.6

Norma Mujica, AgronomistMarfa Palacios, Assoc. Biologist6

Alcira Vera, BiologistWilberto Villano, AgronomistS

PathologyPedro Aley, MS, Plant Pathologist6

Ciro Barrera, MS, Plant PathologistIda Bartolini, MS, BiochemistCarlos Chuquillanqui, MS, Plant PathologistChristian Delgado, MS, Biochemist6

Violeta Flores, BiologistSegundo Fuentes, MS, Plant Pathologist6

Liliam Gutarra, MS, Plant PathologistCharlotte Lizarraga, MS, Plant PathologistHans Pinedo, Agronomist3

Hebert Torres, MS, Plant Pathologist"Jose Luis Zapata, MS, Plant Pathologist, Co­

lombia4

PhysiologyRolando Cabello, MS, Assoc. AgronomistNelly Espinola de Fong, MS, NutritionistRosario Falcon, BiologistM.S. Kadian, PhD, Agronomist, IndiaJoseph Koi, MS, Agronomist, CameroonJose Luis Marca, Ing. Agr.Jorge Roca, BiologistSonia Salas, MS, Assoc. Food ScientistK.C. Thakur, PhD, Breeder, India

Social ScienceCherry Bangalanon, MS, PhilippinesRosario Basay, BA, EconomistPatricio Espinoza, Economist, EcuadorHugo Fano, MS, EconomistCristina Fonseca, MS, Agronomist6

V.S. Khatana, PhD, Socioeconomist, IndiaMarfa Lozano, Computer AssistantLuis Maldonado, BA, EconomistMargaret Ngunjiri, MS, Sociologist, KenyaOscar Ortiz, MS, Agronomist4 ,SMaricel Piniero, Ecologist, PhilippinesVfctor Suarez, MS, StatisticianInge Verdonk, Ir, Nutritionist, Philippines

TrainingNelson Espinoza, Training SpecialistMartha Huanes, Training LogisticsAmerico Valdez, MS, Training Material Spe­

cialist

Research SupportVictor Otazu, PhD, Superintendent, Support

UnitLombardo Cetraro, Biologist, Field & Green­

house Supervisor, San RamonRoberto Duarte, Ing. Agr., Field & Greenhouse

Supervisor, La MolinaHugo Goyas, Ing. Agr., Field & Greenhouse

Supervisor, HuancayoLauro Gomez, Supervisor, Huancayo3Ulises Moreno, PhD, PhysiologistMario Pozo, Ing. Agr., Supervisor, La Molina

Experiment Station4

Miguel Quevedo, Ing. Agr., Off-Station FieldSupervisor, Cajamarca3

Statistics UnitAlfredo Garcia, MS, Experimental StatisticsFelipe de Mendiburu, Statistics Eng.

(IP Progrom RepOft 1995-96 31 7

Consortium CONDESANBlanca Arce, MS, Assoc. Scientist, Quito, Ec­

uadorElias Mujica, MS, Anthropologist, Adjunct

ScientistSAna Maria Ponce, PhD, INFOANDINA Ad­

ministratorSJorge Reinoso, MS, Agric. Economics, Puna,

PerusMario Tapia, PhD, AgroecologistS

Roberto Valdivia, MS, Agronomist, Puna,Perus

Latin America and the Caribbean RegionalOffice

Sven Villagarcia, PhD6

Communications UnitCecilia Lafosse, Chief DesignerGodofredo Lagos, Production Chief

Emma Martinez, MS, Spanish Assistant Edi­tor/Supervisor Media Production

Gigi Chang, MS, Photographer, AudiovisualSection Coordinator

Information Technology UnitEdith Aguilar, Telecommunications Officer4

Jorge Arbulu, Telecommunications SystemsSupervisor3

Monica Arias, BS, Systems Engineer'Pablo Bermudez, Systems Analyst'Liliana Bravo, BS, Systems Engineer2

Oscar Bravo, Microvax Systems Supervisor3

Roberto Castro, BS, Systems DevelopmentEduardo Manchego, Systems Analyst4

Jose Navarrete, Systems Analyst2

Pia Maria Oliden, Systems AnalystEric Romero, BS, Systems EngineerEdgardo Torres, BS, Systems EngineerAlberto Velez, MS, Systems Engineer

LibraryCecilia Ferreyra, Head Librarian

Controller's OfficeMiguel Saavedra, CPA, General AccountantEdgardo de los Rios, CPA, Senior AccountantVilma Escudero, Accountant4

Milagros Patino, BA, Accountant2

318 Stoff

Accounting UnitJorge Bautista, AccountantBlan.ca Joo, CPA, AccountantRosario Pastor, CPA, Senior Accoun-

tantEduardo Peralta, Accountant

Budget UnitDenise Giacoma, CPA, AccountantAlberto Monteblanco, CPA, Senior

AccountantTreasury Unit

Sonnia Solari, Chief CashierLuz Correa, CPA, Accountant (Super­

visor)3

Office of the Director General

Visitors' OfficeRosa Rodriguez, Manager?Mariella Corvetto, Supervisor

Office of the Deputy Director General forFinance and Administration

Haydee Zelaya, Internationally Recruited StaffOfficer

Office of the Executive Officer

Foreign Affairs LiaisonMarcela Checa, Liaison Officer

TravelAna Maria Secada, Supervisor

Logistics and General ServicesAldo Tang, Comdr. (ret.), Manager

Front DeskMicheline Moncloa

MaintenanceAntonio Morillo, Chief

Purchasing SupervisorsArturo AlvarezRoxana Morales Bermudez4

Jose PizarroSecurity

Jorge Locatelli, Capt. (ret.),Supervisor4

TransportationHugo Davis Paredes, Vehicle Main­

tenance OfficerAti/io Guerrero, Vehicle Program-

merJacques Vandernotte, Pi lot4

Djordje Velickovich, Pilot4

Percy Zuzunaga, PilotWarehouse

Jorge Luque, MBA, Supervisor

Human ResourcesLucas Reafio, ManagerJuan Pablo Delgado, Manager4

Auxiliary ServicesMonica Ferreyros, SupervisorSor Lapouble, AssistantCompensationEstanis/ao Perez Aguilar, SupervisorLabor RelationsLuis Caycho, Acting Supervisor2

Medical OfficeDavid Halfin, MDLucero Schmidt, NurseSocial WorkMartha Pierola, Supervisor

ClP Progrom Report 1995-96 31 9

Acronyms and Abbreviations

ACIARACMVDADEFORAEZAFLPAGERIAMOVAANOVAAPAPWARCARTCASPADERUCASPRAD

AUDPCAVAAVBAVRDC

BACBMZBtBWCAASCaMVCGIAR

ClADC1ATCIRNMA

CLADESCMPCMSCONDESAN

CORPOICACOSUDECPRICPRSCpTICRHDASDGISDMDNAELISA

320 Acronyms

Australian Center for International Agricultural ResearchAfrican cassava mosaic virus diseaseAsociaci6n para el Desarrollo Forestal, Ecuadoragroecological zonesamplified fragment length polymorphismAgriculture Genetic Engineering Research Institute, Egyptanalysis of molecular varianceanalysis of variancearracacha potyvirusAndean potato weevilAgriculture Research Center, EgyptAndean root and tuber cropsAsociaci6n para el Desarrollo Rural de Cajamarca, PeruAsian Sweetpotato and Potato Research and Development,

networkarea under the disease progress curvearracacha virus Aarracacha virus BAsian Vegetable Research and Development Center,

Taiwanbacterial artificial chromosomeGerman Ministry for Economic Development and CooperationBacillus thuringiensisbacterial wiltChinese Academy of Agricultural Sciencescauliflower mosaic virusConsultative Group on International Agricultural

ResearchCenter for Integrated Agricultural Development, ChinaCentro Internacional de Agricultura Tropical, ColombiaCentro de Investigaciones de Recursos Naturales y Medio

Ambiente, PeruConsorcio Latinoamericano de Agroecologia y Desarrollocritical moisture pointcytoplasmic male steri IityConsortium for the Sustainable Development of the

Andean EcoregionCorporaci6n del Instituto Colombiano AgropecuarioCooperaci6n Tecnica SuizaCentral Potato Research Institute, IndiaCentral Potato Research Station, Indiacowpea trypsin inhibitorHorticultural Research Center, Canadadays after sowingDirectorate General for International Cooperation, Netherlands

dry matterdeoxyribonucleic acidenzyme-linked immunosorbent assay

ESEAPEVSFAOFFSFORTIPAPA

GAGAASGAnGBFGEGllBGMIGVHECHIHiIARCIBTAICAICARICARDA

ICIMOD

ICMICRAFIDIAPIDMIDRCIFPRIIIBCIICA

IITAIlRIINIAINIAINIAP

INIBAP

INIFAP

INIVITIPGRI

IPMKARllAClBlMFMDSMENAMIPMSU

East and Southeast Asia and the Pacific, ClP regionevaporative rustic storesFood and Agriculture Organization of the United Nationsfarmer field schoolsFortalecimiento de la Investigaci6n y Producci6n de Semilla de

Papa en el Ecuadorgibberellic acidGuandong Academy of Agricultural Sciences, ChinaGeneral Agreement on Tariffs and TradeSociety for Biotechnological Research, Germanygenotype x environmentGlobal Initiative on late BlightGlobal Mountain Initiativegranulosis virushen egg cystatinharvest indexheterozygosity indexinternational agricultural research centerInstituto Boliviano de Tecnologia AgropecuariaInstituto Colombiano AgropecuarioIndian Council for Agricultural ResearchInternational Center for Agricultural Research in the Dry Areas,

SyriaInternational Centre for Integrated MountainDevelopment, Nepalintegrated crop managementInternational Centre for Research in Agroforestry, KenyaInstituto de Investigaciones Agropecuarias de Panamaintegrated disease managementInternational Development Research Centre, CanadaInternational Food Policy Research Institute, USAInternational Institute of Biological Control, KenyaInstituto Interamericano de Cooperaci6n para la Agricultura,

Costa RicaInternational Institute of Tropical Agriculture, NigeriaInternational Livestock Research Institute, KenyaInstituto Nacional de Investigaciones Agropecuarias, UruguayInstituto Nacional de Investigaci6n Agraria, PeruInstituto Nacional Aut6nomo de Investigaciones Agropecuarias,

EcuadorInternational Network for the Improvement of Banana and

Plantain, FranceInstituto Nacional de Investigaciones Forestales y Agropecuarias,

MexicoInstituto Nacional de Investigaci6n de Viandas Tropicales, CubaInternational Plant Genetic Resources Institute (formerly

International Board for Plant Genetic Resources), Italyintegrated pest managementKenya Agricultural Research Institutelatin America and the Caribbean, CIP regionlate blightleafminer flymultidimensional scalingMiddle East and North Africa, CIP regionPrograma de Manejo Integrado de Plagas, Dominican RepublicMichigan State University, USA

(IP Progrom Report 1995-96 321

MvNAARI

NARONARSNASHNGONPTNRIOCIODAPAGEPapMVPBCPBRVPCRPICPICTIPAPA

PLRVPMSFPNGPPRIPQSPRAPRACIPA

PRAPACE

PRECODEPA

PROCIPA

PRODAR

PROINPAPRONAMACHCS

PSTVdPTMPVPPVSPYXPVYQTLRAPDR/FRFLPRHRILETRNARRDRT-PCRSAASSADC

322 Acronyms

marker valueNamulonge Agricultural and Animal Production Research Institute,

UgandaNational Research Organization, Ugandanational agricultural research systemsnucleic acid spot hybridizationnongovernmental organizationneomycin phosphotransferaseNatural Resources Institute, UKoryzacystatin IOverseas Development Administration, UKpolyacrylamide gel electrophoresispapaya mosaic virusPotato Base Collection at CIPpotato black ringspot viruspolymerase chain reactionpolymorphic index contentPrograma Internacional Cooperativo del Tiz6n Tardio de la Papa,

Mexicopotato leafroll virusphenyl methylsu Ifonyl fluoridePapua New GuineaPlant Protection Research Institute, EgyptPlant Quarantine Station, Kenyaparticipatory rural appraisalPrograma Andino Cooperativo de Investigaci6n en Papa, ClP

networkProgramme Regional de I'Amelioration de la Culture de la Pomme

de Terre et de la Patate Douce en Afrique Centrale et de l'Est, ClPnetwork

Programa Regional Cooperativo de Papa, ClP network in CentralAmerica and the Caribbean

Programa Cooperativo de Investigaciones en Papa, ClP network inSouthern Cone

Programa de Desarrollo de la Agroindustria Rural para America Latinay el Caribe

Proyecto de Investigaci6n de la Papa, BoliviaPrograma Nacional de Manejo de Cuencas Hidrograficas y

Conservaci6n de Suelos, Perupotato spindle tuber viroidpotato tuber mothpotato vi rus Ppotato virus Spotato virus Xpotato virus Yquantitative trait locirandomly amplified polymorphic DNAroot to foliage ratiorestriction fragment length polymorphismrelative humidityResearch Institute for Legumes and Tubers, Indonesiaribonucleic acidRed River Delta, Vietnamreverse transcription polymerase chain reactionSichuan Academy of Agricultural Sciences, ChinaSouthern African Development Community

SANREMSAPPRADSARRNETSBTISOCSEINPASENASENASASINGERSMSMCSPFMVSPVDSSASWATALPUYTAPTCRCTMVTMVTPSUKDWUMATAUMVUNAUNALMUNCUNCPUNEPUNSAACUNSCHUNTUPWARDURPUSAIDUSEPAUVCVASIVTMoVWARDAWBVWWRXSPRC

Sustainable Agricultural and Natural Resource ManagementSoutheast Asian Program for Potato Research and DevelopmentSouthern Africa Root Crop Research Networksoybean trypsin inhibitorSwiss Development CooperationSemilla e Investigaci6n en Papa, PeruServicio Nacional de Aprendizaje, ColombiaServicio Nacional de Sanidad Agraria, PeruSystemwide Information Network for Genetic Resourcessimple matching coefficientsseed moisture contentsweetpotato feathery mottle virussweetpotato virus diseaseSub-Saharan Africa, CIP regionSouth and West Asia, CIP region

Grupo de Investigaci6n y Desarrollo de la Ciencia Andina, Perutransmission access periodTropical Crops Research Center, Bangladeshtobacco mosaic virustotal marker variancetrue potato seed

Duta Wacana Christian University, IndonesiaUnidad Municipal de Asistencia Tecnica Agropecuaria, Colombiaullucus mosaic virusUniversidad Nacional del Altiplano, PeruUniversidad Nacional Agraria La Molina, PeruUniversidad Nacional de Cajamarca, PeruUniversidad Nacional del Centro del PeruUnited Nations Environment ProgrammeUniversidad Nacional de San Antonio Abad del Cusco, PeruUniversidad Nacional de San Crist6bal de Huamanga, PeruUniversity of Turku, Finland

Users' Perspectives With Agricultural Research and DevelopmentUniversidad Ricardo Palma, PeruUnited States Agency for International DevelopmentUnited States Environmental Protection Agencyullucus virus CVietnam Agricultural Science Institutevelvet tobacco mottle virusWest Africa Rice Development Association, Cote d'ivoirewhitefly-borne c1osteroviruswatery wound rotXuzhou Sweet Potato Research Center, China

(IP Program Report 1995-96 323