Vegetable and Fruit Production

Vegetable andFruit Production

Vegetable and

Fruit Production

Vegetable and Fruit Production

Brinda Bhatt

Published by Vidya Books,

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Brinda Bhatt

ISBN: 978-93-5429-437-2

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Contents

Chapter 1 Backdrop of Vegetables ...................................................................................... 1

Chapter 2 Significance of Fruit and Vegetables .............................................................. 23

Chapter 3 Technology of Fruit Products .......................................................................... 61

Chapter 4 Fruit Crop Cultivation and Development ................................................... 107

Chapter 5 Tropical Fruit Crops ........................................................................................ 143

Chapter 6 Soil Quality in Vegetable and Fruit Production .......................................... 179

1

Backdrop of Vegetables

Most seeds normally remain viable for 2 or 3 years if stored under goodconditions. To grow best vegetables either for home garden or for growingcommercially try only certified seeds with, trueness to type and freedom fromcertain diseases. Good seeds are clean, viable, free from disease and true tothe name variety. Therefore, buy only from seed firm of known integrity. Highyielding, high price seeds should have 90% germination. Seeds of 50%germination is very poor.

HISTORY OF VEGETABLES

VEGETABLES IN T HE EARLY CHRIST IAN PERIOD

The early Middle Ages is a murky period for the study of vegetables, buta copy (in the Austrian State Library at Vienna) of the Codex of Dioskoridesdating from 500 to 511 C.E. is illuminated with pictures of plants. The drawingsare fairly accurate and convey the important physical characteristics of thevegetables and herbs shown. Thus it is possible to determine that a leek onfolio 278 belongs to the Kurrat Group, an ancient type of salad leek mentionedearlier and still grown in the Near East.

The Codex of Dioskorides is medical in nature, dealing with the health anddietary aspects of the plants discussed. For a horticultural companion, theGheoponika of Kassianos Bassos, a tenth-century reworking of several olderagricultural treatises, provides rules for the cultivation of garden vegetables,thus offering some insights into the seasonal food cycle, both horticulturaland culinary, in the old Byzantine East.

More specifically, the role of the Gheoponika in the provisioning ofConstantinople with fresh vegetables has been studied by several historians,most importantly by Johannes Koder (1993). When taken together with theBook of the Eparch (prefect of Constantinople) regulating merchants and guildsduring the reign of Leo VI (886–912), a relatively detailed picture of marketgardening falls into place.

It is perhaps significant to note that by the 1100s many villages in Bulgariawere given imperial privileges that freed them of military duty in exchangefor producing food for the court. It is for this reason that the Bulgarians havelong been called the gardeners of the Balkans, a status they maintained evenunder later Ottoman rule.

In the West, the eighth century Capitulare de villis of the Holy RomanEmperor Charlemagne is quite valuable for its references to gardens. Forexample, the ravocaulos of that document is believed to refer to a variety ofkohlrabi. However, the most priceless garden record is a parchment drawingof the garden plan of the Cloister of St. Gall in Switzerland surviving fromthe early 800s. It provides a detailed look at how the Roman kitchen gardenbecame transmogrified into a source of both food and medical plants. Sixteenplants are discernible on the plan, including cucumbers, melons, cowpeas,bottle gourds, and smallage (celery resembling parsley). Most important, theyare organized into rectangular raised beds. This is one of the earliest referencesextant to this common garden practice, but it was not unique.

The Hortulus of Walahfrid Strabo, abbot (from 838 to 849) of the Cloisterof Reichenau on an island in Lake Constance, makes reference to a similarnumber of plants, again arranged in raised rectangular beds. Strabo’s Latinpoems about his garden discuss the uses of both herbs and vegetables and isthe oldest surviving source on gardening written in Europe during the MiddleAges. Most interesting of all, archaeological exploration of the abbey site hasrevealed that it was constructed from the recycled ruins of an abandonedRoman villa and that the layout of the garden more or less followed theoutlines of the ancient one.

The implication is that the Roman gardening tradition maintained by thewealthy during imperial times did not fully disappear at the outset of theMiddle Ages. Many estate gardens disappeared completely due to wars andpillaging, but in some regions they simply became fewer in number and passedinto non-Roman hands.

Chateau Ausone near Saint-Emilion in Bordeaux is a famous example ofthis continuity, although its fame rests on wine not gardens. The archaeologicallink is not as clear when it comes to the vegetables themselves, since botanicalresidues, especially seeds, impose certain limitations on what can be retrievedfor science. A carrot seed is indistinguishable from a wild carrot seed andwill not tell how the root was shaped or even its colour. Unfortunately, seedsare mostly what one has to work with from medieval sites, although someinferences can be revealing. Cucumber seeds show up in Polish sites in the900s, thus establishing a bottom line for a vegetable much associated withPolish national cookery. Carbonized fava bean plants from North Germanyfrom the same period reveal that, after the beans were harvested (as winterfare), the plants were used as straw in barns. Seeds, however, do help untangledates of introduction, and one thing that scholars have learned from medieval


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archaeology is that the vegetable world was not static, as historians have ledus to believe in the past.

The broad, flat fava bean, which is the preferred sort for modern cookery,did not appear until the 800s in Spain. This is only one example of vegetablebreeding (probably through highly controlled selection) that took place duringthe Middle Ages, although innovation was indeed slow by present-daystandards. Some agricultural historians have suggested that it was the Arabswho created these new types of vegetables—the cauliflower, for example.What can be documented from surviving Arab literary sources is rapiddissemination, but the westward movement of plants in general andvegetables in particular was far more complex than hitherto presumed andremains an area of research ripe for future exploration.

VEGETABLES IN EGYPT

There is a large body of published material on the history of gardeningin ancient and pre-Islamic Egypt, but there are no books per se devotedexclusively to vegetables. Orchards, trees, flora, landscape gardening, and evenaquatic plants have received thorough coverage, yet the vegetable stands alonein this curious neglect. Vegetables in general have been viewed as povertyfood by most cultures, especially when they form a large portion of peasantdiet. Egypt was no different in this regard.

The fine gardens of ancient Egypt were enclosed like those ofMesopotamia and contained trees, flowers, even ponds for fish and ducks.The gardens of the peasants were mostly simple agricultural plots devoted toa specific mix of vegetable crops associated with the local economy, as, forexample, lentil or onion growing for absentee landlords in large urban centerslike Alexandria. On the other hand, vegetable gardens within temple precinctswere often quite elaborate and were intended to supply the priesthood witha full range of food as well as offerings for the deity. Lettuce, for example,was important to the cult of Amun-Min, thus its cultivation held both culinaryand religious significance. Indeed, temple gardens were considered to be partof heaven, like the temple itself, so vegetables from those gardens achieved apurity unlike those from the common world.

Papyri and tomb paintings have provided a rich array of material dealingwith the common vegetables of the day, although not much is known abouttheir actual preparation as food. The most commonly mentioned vegetableswere lentils, leeks, lotus, melons, gourds, garlic, asphodel (grown for its bulb),fava beans, chickpeas, fenugreek (ground as flour), garland chrysanthemum(now popular in Asian cooking), cucumbers, onions, lettuce, and mallow.Egypt also served as a conduit for the introduction of watermelons fromtropical Africa and, during the late Ptolemaic Period, for the introduction ofrice, taro, and sugar cane from Trapobane (ancient Sri Lanka). Due to theirdependence on specialized irrigation and cultivation techniques, none of the


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last three plants spread beyond the eastern Mediterranean until after Arabconquest.

The Greek occupation of Egypt under the Ptolemys radically altered theEgyptian vegetable garden, both with new introductions and in lastingterminologies. Molokhe or mallow (Malva parviflora), which was once soimportant to Greek cookery both as a green sauce and as an ingredient incomplex recipes, also supplied leaves used like grape leaves for makingdolmas. The Egyptians transferred the Greek name to a native wild plant nowknown as Jews mallow (Corchorus olitorus), which was similarly used in greensauces. It is still called molkhia in Egyptian Arabic. The use of the same namefor plants of a different genus or species is one of the lasting ambiguitiesinherited from the ancients, who were more apt to lump vegetables togetheraccording to how they were used, as in the case of the Roman propensity fortreating carrots, parsnips, and parsley root as pastinaca.

T HE VEGETABLES OF ANCIENT GREECE AND ROM E

There are few surviving writings from the Greeks and Romans that donot mention food and vegetables in some manner. It is known from quotesand citations in works like the Deipnosophists of Athenaeus that many bookson gardening and agriculture once existed but are now lost. Athenaeus himselflavished considerable attention on foodstuffs, none the least being vegetables.His interests ranged from toasted chickpeas (still a snack food in theMediterranean) to the medical applications of beets and carrots as vermifugesor a good dish of cabbage to treat a hangover. He even cited the knownvarieties of lettuce, garlic, fava beans, and many other garden plants in aneffort to differentiate which were the best from a connoisseur’s point of view.

The surviving Roman work most easily accessible to the general readeris also by another connoisseur, an eccentric called Apicius, whose detailedrecipes give specific hints about the role vegetables played in the haute cuisineof imperial Rome. For example, asparagus was baked in eggy casseroles calledpatinae, mallow was commonly added to barley soup, celery made a goodstuffing for suckling pig, and turnips marry well with baked duck. There isalso scattered advice on when to harvest certain vegetables, as in the case ofstinging nettles, which only loose their prickly character when cooked or dried.

Many other works could be cited, such as Columella’s On Agriculture andespecially Pliny’s monumental Natural History, but the medical writings ofthe imperial physician Galen are perhaps the richest in detail, since there isconsiderable commentary on the diet of peasants and farmers and the sortsof vegetables they ate. The aristocratic tone and intended readership of mostof the writings that have survived from this period do not provide the kindof first hand observations one might expect from a true master gardener,although Pliny’s eye was in fact well nuanced to such details—yet some ofhis botanical “facts” are obviously scrambled and second-hand. And while it


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is true Columella certainly knew how to run an estate, he was not thevegetable gardener.

Furthermore, aside from comments about asparagus and cabbage, Cato’streatise On Agriculture makes only passing reference to vegetables—be certainto grow them near cities. While this allusion does confirm the existence ofwell-organized market gardening, Cato’s treatise is so loaded with ideologyabout salty Romanness (Romanitas) and the purity of certain rigorous lifestylesthat any conclusions drawn from him must be done so with definitereservations. However, it is fairly clear from these and other ancient authorsthat quite a few cities had developed market gardening to a high degree andeven specialized in the cultivation and export of vegetable produce to Romeand other large urban centers.

For example, Cyrene in present-day Libya was well-known in ancienttimes for its silphium, fragrant saffron, and a mild-tasting tuber now generallyidentified as taro. It was also the centre for the export of the so-called wildartichoke (Cynara cornigera Lindl.), whose domestication was introduced earlyinto Cyprus, Libya, and Carthage from the Levant. This handsome plant isdepicted on surviving mosaics in the House of Dionysios at Paphos, Cyprus,and in a mosaic in the Bardo Museum at Tunis. The Roman farmers of Spainand Italy evidently adapted the novel idea of harvesting the flower bud as adelicacy to their local wild cardoons because the artichoke of the westernMediterranean is a subspecies derived genetically from the cardoon (Cynaracardunculus L.), not from a wild artichoke ancestor. Buds of the milk thistle,blessed thistle, and safflower were also similarly harvested and eaten.

The dissemination of the artichoke, or at least of the horticulturaltechnology required to cultivate it for food, brings up the larger question ofplant exchange during the height of the Roman Empire. Commerce flowed toand from the far-flung provinces in a manner only replicated by the EuropeanUnion. Archaeology has indeed confirmed that foodstuffs moved quite easilyfrom one place to another, with such exotics as rice turning up in sites inGermany and England. There is also indisputable evidence that, among thearistocracy at least, country life on the great estates attempted to imitate thecourt life of imperial Rome. Gardens excavated from villa sites have confirmedthis. On the local level, however, Mediterranean cuisine and Mediterraneanvegetables were not readily assimilated among the general populace. JoanAlcock’s study of food in Roman Britain (2001), based on overwhelmingarchaeological evidence, reached the conclusion that assimilation was selective,and it was this selectivity that gave rise to the regional cookeries thateventually provided a link of continuity with the regional cookeries of theMiddle Ages. This is also the growing consensus of archaeologists in otherparts of Europe. Thus, the old saw that “the Romans introduced it” must berequalified, especially since quite a number of vegetables were cultivated insome regions long before the Romans arrived. Cabbage, especially the kales,


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originated in northern Europe, and in fact, the English words for kale andcabbage are Celtic in origin, as are the German words Kabbis and Kohl, not tomention the Latin brassica and caulis. This is evidence in itself that the vegetableexchange during Roman times was complex and two-way, with the Romansthemselves learning new things from conquered peoples.

A broader look at Roman literature of all types is especially useful indrawing general conclusions about the state of vegetable gardening from thattime. For example, Pliny parodied “gastronomic prodigies,” monstervegetables and fruits valued for their size alone. This would suggest that somemarket gardeners were well acquainted with horticultural practices based oncareful seed selection, cold frame techniques, and the manuring of plants atcritical periods of growth, much like the modern-day cult of the monsterpumpkin or watermelon.

There is also a great deal of information concerning value judgmentsabout the role of vegetables in the diet and their cultural significance. ManyRoman satires mention garlic as a food only fit for galley slaves and peasantsor as something eaten only by soldiers going off to war (garlic heats up thebody and therefore creates a warlike spirit). The general drift is that anythingflavoured with garlic is therefore rustic and unrefined and as much an antidoteto poison as it is to the consuming flames of love (what sweet kiss is notwithered by the scorpion sting of garlic breath?). Likewise, fava beans areeaten by jurymen in order to stay awake during trials, their noisy flatulencyproviding an echoing thunder of divine approval or of legal derision.

The most commonly mentioned vegetables in Roman literary sourcesinclude many still known, although in shape and habit they probably did notresemble modern varieties. The list includes turnips, radishes, rocket (arugulato American grocers), leeks, lentils, lettuce, orach, Old World gourds (eatenyoung like zucchinis), cabbage, onion, peas, chickpeas, fava beans, cucumbers,asparagus, cowpeas, beets, beet chards, sprouting broccoli, watermelon, garlic,mallow, dock, chickling vetch, and blite—otherwise known as purpleamaranth (Amaranthus lividus).

A number of scholars have taken the liberty of translating blitum (blite)as spinach, and this has greatly added to the confusion about the culinaryhistory of spinach because blitum is not true spinach. However, somethingcalled barbaricum bliteum (barbarian blite) also surfaces in Roman literature.This is either true spinach as cultivated by the Armenians and Persians orelse good-king-henry, so important to the ritual cookery of the ancient Gauls—the leaves of both plants are similarly shaped. In any case, this mysteryvegetable was considered insipid eating and was equated with crudeness andstupidity (insipid people were people who lacked “flavour”).

Some of these vegetables also carried a great deal of symbolic baggage,especially in connection with religious cults. Mallow (moloche) was consideredone of the purest sacrifices for Apollo Genetor at Delos, and Pythagoras himself


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was said to have lived on it as part of his vegetarian dietary regime because it“washes” the stomach.

Lettuce was associated with the gruesome death of Adonis, theprepubescent lover of Aphrodite, who hid among lettuce before he was goredto death by a wild boar. Thus lettuce was associated with male sterility,effeminacy, and cowardice, and generally was viewed as a suppressant ofsexual performance.

Gardens of Adonis were planted in pots or baskets during the heat ofsummer and then allowed to die prematurely on the roofs of houses duringthe feast of Adonia (19 July during the Roman Empire) as symbolic evidenceof the boy’s sexual prowess, which produced no “seed” or fruit. Significantly,these little gardens consisted of barley, wheat, lettuce, and fennel, each planthighly symbolic of some aspect of fertility yet a total inversion of what wasunderstood to be garden abundance.

Interestingly, a distinctive lettuce dedicated to Gauas (the CypriotAdonis), and later known as “Cyprian” during the Byzantine period, wasdiscovered in a Serbian monastery by the U.S. Department of Agriculture inthe early twentieth century and is preserved in several American seed banks.It is physically similar to the pointed-leaf lettuce depicted in the medievalTacuinum Sanitatis (Arano, 1976) of the eleventh-century Syrian Christianphysician Ibn Botlan. By virtue of this continuity, at least in form andappearance, Cyprian lettuce is a true heirloom variety, a category of vegetablethat will be dealt with later in this discussion.

VEGETABLES AND T HE ARAB DIASPORA

The agricultural historian Andrew Watson has long promoted the ideathat an agricultural revolution took place under early Islamic rule in theeastern Mediterranean, a revolution that was carried westward into NorthAfrica and Spain. This has important implications for the movement ofvegetable plants. However, other scholarship has questioned this thesis. Thereis growing evidence that the revolution was already taking place during thelate Byzantine period and that it consisted of newer ways of irrigating landand reclaiming marshes so more intensive forms of agriculture could beundertaken. Without entering the question of who invented what, two criticalpoints are undeniable: the technology came out of Persia and South India (thevast irrigation systems in Sri Lanka were well known even to the Greeks),and its spread westward was made possible by the political stability that Arabconquest brought to the regions under its control. It is easy to point to theconcentration of wealth in bright spots such as Syria (Damascus and Baghdadin particular), Egypt, and al-Andalus in Spain, but there was an economicimplosion in other parts of the newly formed empire. The family papers ofthe Ibn’Awkal merchants of eleventh-century Egypt reveal a great deal aboutindustrial crops like Egyptian flax or high-profit goods like black pepper,


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indigo, and sal ammoniac, but information on common garden vegetables israther limited. That is, unless one looks at medical literature and cookerybooks. The most heavily used culinary source is also one of the oldest: theKitab al-tabikh, otherwise known as the Baghdad cookery book. It was writtendown in 1226, although internal evidence clearly indicates that the materialwas compiled from several much earlier sources, some of which were notArabic. This ambiguity is one of the difficulties in using cookbooks to pinpointthe introduction of new vegetables. But that said, there are other Arabiccookery manuscripts equally rich in detail surviving from the Middle Ages,such as the Manuscrito Anonimo of Moorish Spain, and all of the recipes nomatter what the source are fairly clear about the role vegetables played in thediet of the times.

There is certainly no ambiguity in the Baghdad cookery book about theuse of eggplants and no doubt at all that the sort discussed had dark blackskin (there are directions for removing it). The book also makes amplereference to fava beans, cardoons, rhubarb, leeks, the ridged cucumber(Armenian snake melon), carrots, gourds, taro, cultivated purslane, turnips,sweet fennel, and spinach. There are also references to a form of cabbagecommonly translated into English as cauliflower. Without a picture, one cannotbe sure (it could be a type of broccoli), but since true cauliflower evidentlyevolved in the Dead Cities region of northwestern Syria, it is quite likely thatthis luxury vegetable migrated during the early 800s with its growers whenthey resettled elsewhere—a small group of those Syrian Christians emigratedto the Karpasia district of Cyprus, where cauliflower was first observed bypilgrims to the Holy Land later in the Middle Ages. The cauliflower is notmentioned in European scientific works until specimens are discussed byDodonaeus in 1560. By that time Cypriot seed was being exported to northernEurope via Venice.

One is also treated with a rich array of vegetables in another work calledKitab Wasf al-Atima al-Mutada (Description of Familiar Foods) written in 1373.Of particular interest is the differentiation of several types of leeks, indicatingnot only distinct varieties but also distinct culinary uses at different stages ofdevelopment—indirect evidence of a highly evolved sense of marketgardening. Four sorts of leek are mentioned: the vegetable leek (kurrath baql),the Nabatean leek, the table leek, and the Syrian leek. The first is not a varietybut rather a spring leek, young greens similar in character to Chinese garlicchives. The Nabatean leek may be equated with the modern salad leek of Iraq,a member of the Kurrat Group, short in height and rather deep-rooted. Thetable leek is a blanched leek similar to the Catalan Calcot onion, and indeedthe cultural technique of burying them in deep trenches may be the same.The Syrian leek is the kephaloton of medieval Cyprus, a Greek word derivedfrom Syrian quaflot, a leek with an unusually large bulb. This plant is thegenetic ancestor of the modern elephant garlic. Under the name Porrum


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Syriacum, it was first illustrated in European botanical literature byTabernaemontanus in 1588. Arab books dealing with cookery exhibit anundeniable passion for elegant preparations, even with simple vegetables. Butsuch food was the privilege of the aristocratic few, and the wealth thatsustained that lifestyle was soon to fade with the economic upheavals causedby the Crusades. Until the late twentieth century, historians have greatlyunderestimated the exchanges that took place after the establishment of Latinfootholds in the Levant and Byzantium or the role of large Christian minoritiesthat persisted in Egypt and Syria during the early Muslim period.

The Nestorian or East Syrian Church, which spread into Persia,established strong trading communities in China and Malabar as well as inCyprus, where the Nestorian Lakhan family became extremely powerful basedon trade in medical aloes. One line of trade and plant exchange went throughTabriz in Persia overland to the Caucasian kingdom of Georgia and the GreekEmpire of Trebizond on the north coast of modern Turkey, all to circumventthe Arabs. That this Black Sea entry was an important route for the movementof Asian food plants westward may be inferred from an eleventh-centuryByzantine reference to the “citrons” of Anatolia, a variety of lemon introducedvia Georgia and Armenia and still preserved in Georgian botanical collections.Eggplants also followed this route. European contact with foods of the Arabworld was not limited to the crusading troops that went to the Holy Landand returned. The Latin Kingdom of Jerusalem (1099–1291), the Principalityof Achaea (1205–1430), a French feudal state established in Greece with itscapital at Mistra, a Catalan principality centred on Athens, various Venetianand Genovese ports, and the sister kingdoms of Cilicia (1080–1375) in AsiaMinor and on Cyprus (1192–1489) were all characterized by colonialaristocracies with highly orientalized foodways.

The last kingdoms, especially that of Cyprus due to a Papal Bull, servedas conduits for the spice trade with the Muslim world. In the case of Cyprus,the kingdom lent its name to an international style of cookery mentioned innumerous medieval cookbooks. More important, the intermarriage of wealthyLatins in the Levant with European nobility, particularly with families inAragon and in northern Italy, brought to Europe a constant influx of personalcooks, gardeners, and retainers schooled in eastern Mediterranean ways. It isnot surprising that some of the earliest references to exotic vegetables likeeggplants, cauliflowers, okra, and numerous sorts of Near Eastern melonsshow up in late medieval Italy.

VEGETABLES IN T HE BAROQUE PERIOD

The seventeenth century witnessed a revolution in botanical science andthe proliferation of books devoted to illustrating plants and vegetables frommany parts of the world, including new introductions from Asia and theAmericas. Francisco Hernandez’s Nova Plantarum was devoted almost


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exclusively to the foods of Mexico and included native names for the plants.His woodcut illustrations offer a priceless look at the characteristics of commonvegetables then grown in New Spain, including the lowly miltomatl ortomatillo (Physalis ixocarpa) now popular in Southwest American cooking.Other books containing strange designations like Pomum amoris majus fructuluteo (large yellow fruited love apple or, more simply, yellow tomato) remindone how much lack of order prevailed in the scientific naming of newlydiscovered vegetables and how much has changed since Linneaus imposedorder on the world of plants in the eighteenth century. Names like bamiaAegypitiaca (Egyptian okra—bamya is actually a Syrian word) of one authormight become “ladies’ fingers” of the next. Likewise the lactuca hispanica(Spanish lettuce) of one author was the Cos or Roman lettuce of another, thenames more often than not reflecting the source of seed rather than the trueorigin and history of the vegetable. One of the most fashionable cabbages ofthe period was the so-called Brassica tophosa, better known as black Tuscanpalm tree kale, “rediscovered” by American seeds-people under the newmoniker “dinosaur kale.” The penchant for fanciful names has not changed.If a generalization can be made about the seventeenth century, it is that therare and exotic vegetable of the previous century gradually became the dailyfare of the urban middle class by 1700.

Plant breeding, especially in Holland, brought many new sorts ofvegetables onto the market. Named varieties of potatoes, carrots, celery,chicory, peas, and turnips soon proliferated in kinds and colours. Added tothis roster were newly discovered Asian foods, like Malabar spinach (Basellaalba), introduced from Java in 1688. Handbooks on plant breeding were evenpublished, one of the earliest in English being Walter Sharrock’s History of thePropagation and Improvement of Vegetables (1660). From this time on, thevegetable undergoes a steady refinement with emphasis on greater delicacyof flavour, more beautiful shape, and increasing tenderness.

Much of this was directly connected with shifts taking place in cookery,especially the use of vegetables in sauces and elaborately prepared dishes.Vegetables were also given ornamental value with paring knives, so turnipsfeathered out into birds, carrots unwound into golden fish, and the cookbooksof the day are full of illustrations showing how to do this. Most notably,however, the vegetable became a prized market commodity; growing ofvegetables, a respectable line of work for the honest laborer; and perioddepictions of market scenes never fail to convey the impression that only thebest has been laid before the eye.

Aside from shifts in cookery, the virtues of country life and the pursuitof its simple pleasures helped elevate vegetable gardening as a worthy andgenteel pastime. Jan van der Groen’s Den Nederlandtsen Hovenier was extremelyinfluential in this respect, as were Nicolas de Bonnefon’s Les delices de lacampagne and Le jardinier francois in France.


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All of these works were translated into several languages and includedspecific discussions of vegetable varieties and cooking tips. Under fava beans,for example, Bonnefon recommended several different methods ofpreparation, including fricassees like peas or boiled plain with slices of bacon,noting that fresh green savoury went “marvelously well” with any fava beandish.

Not the least important, from the standpoint of vegetables, was JohnEvelyn’s Acetaria: A Discourse on Sallets, which discussed most of the populartypes of vegetables of the day, especially ways to employ them raw orsemicooked in salads. Of earth chestnuts (Bunium bulbocastanum) he remarked:“the Rind pard off, they are eaten crude by Rustics, with a little Pepper; butare best when boil’d like other Roots, or in Pottage rather, and are sweet andnourishing.”

VEGETABLES IN T HE ENLIGHT ENM ENT

The idea that vegetables recaptured the original wholesomeness of Edenbecame an underlying theme for many of the more offbeat cookbooks of theeighteenth century, with Adam’s Luxury and Eve’s Cookery considered one ofthe most typical.

The underlying philosophies expressed in these books may be said torepresent the intellectual forerunners of true vegetarianism, which was indeedpracticed in colonial North America by the so-called White Friends, a groupof Quakers who wore clothing of unbleached cloth.

The most highly organized vegetarians in early North America, however,were the Bible Christians, who expanded from England in 1816. MarthaBrotherton’s Vegetable Cookery became the dietary handbook for this group.The European penchant for country life was quickly transferred to Englandduring the 1600s and from there to colonial America. Doubtless it achievedits American apotheosis in such famous estates as William Penn’s “PennsburyManor” along the Delaware River, Thomas Jefferson’s “Monticello” inVirginia, William Hamilton’s “Woodlands” near Philadelphia, and CharlesCarroll’s “Mount Clare” in Baltimore. Jefferson’s personal garden accountbook, published by the American Philosophical Society in 1944, remains alasting testimony to the central role that kitchen gardens—and vegetables inparticular—played in this manorial lifestyle.

It was on such estates as these that many of the Old World exotics werefirst introduced to North America. Charles Norris of Philadelphia, for example,is known to have raised black-skinned eggplants, since a letter survives from1763 imploring him for seed. Many of the most popular vegetables of thisperiod can be found in Philip Miller’s Gardener’s and Botanist’s Dictionary, andremarkable as it may seem, some of Miller’s vegetables are extant, amongthem red celery, Spotted Aleppo and Silesia lettuces, spinach beets, anddomesticated sea kale.


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VEGETABLES IN T HE RENAISSANCE

The Carrara Herbal, created sometime before 1403, was one of the firstlate medieval herbals to depict plants and vegetables accurately, although itmay have been based on a now lost Byzantine prototype. Such illustratedhandbooks of health, as well as numerous herbals, offer a rich visual recordof the sorts of vegetables deemed. The beautiful gardens witnessed bytravellers through the Latin East were now replicated in Italy but with thegoal for reattaining a glorious Roman past. The Italian pleasure gardens ofthis period so impressed Casimir the Great of Poland that he installed one inCracow during the 1360s, complete with cold frames for forcing Mediterraneanvegetables. In short, the vegetable garden once again becomes an object ofstatus.

The discovery of printing, followed quickly by the discovery of the NewWorld and the heady harvest of its vegetable riches, only accelerated a questfor new and exotic things to ornament the gardens of the rich and powerful.Tomatoes, peppers, potatoes, sunflowers, beans, sweet potatoes, new sorts ofpumpkins, and a new kind of wheat called maize fill the pages of botanicaltreatises and plant books of the period. The 1500s may be characterized as acentury during which botanists attempted to organize the vegetable worldinto some type of scientific order, although that “order” by modern standardswas quite chaotic. For example, a confusing observation is that the Jerusalemartichoke from North America (not from Jerusalem and not an artichoke) isknown as Flos solis Farnesianus (Farnese sunflower) in reference to the factthat the gardens at the Villa Farnese in Rome provided several botanists withthe first known specimens. Sorting out such conflicting nomenclature hasplagued garden historians ever since.

However, botanical gardens were established in this century, the first in1545 at the University of Padua, and some of the greatest botanical works ofthe Renaissance were issued during this era, especially those devoted tocataloging the gardens of such important plantsmen as Conrad Gesner inSwitzerland (1561), Georg Fabricius in Meissen, Germany (1569), andCamerarius in Nurnberg (1588). All of these books contain valuable woodcutsdepicting vegetables, and many medieval favourites like skirret (Sium sisarum)and monk’s rhubarb (Rumex patientia) are shown for the first time. Vegetablesalso figured prominently in Renaissance art and paintings, especially the stilllife genre. Among the most whimsical vegetable compositions are those bythe court painter Giuseppe Arcimboldo (c. 1527–1593), who used vegetablesand fruits to create faces and other conceits.

The most significant body of literature, however, was the garden guidesthat discussed not only specific vegetable varieties but also how to grow them.The French work known as L’agriculture ou la maison rustique, first publishedin Latin (1535) by the Paris printer Charles Estienne, was soon translated into


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most major European languages. Marco Bussato’s Giardino di agricultura wasalso extremely influential, as was Johann Coler’s Oeconomica ruralis et domestica.The great classic, however, was Oliver de Serre’s Theatre d’agriculture, whichbecame a standard garden book for much of the next century. This greatoutpouring of garden knowledge was capped in many ways by the lavishlyillustrated Hortus Eystettensis assembled by Basilius Besler in 1613 for hispatron plant collector, the bishop of Eichstatt in Bavaria. Not only did thegood bishop own prize specimens of rare eggplants, balsam apple (Momordicabalsamina), tomatoes, and domesticated asparagus, his potted prickly pearcactus from the New World required a wooden superstructure to hold themonster plant in place.

RESEARCH ON VEGETABLES

The major objectives of research on vegetables in India is improvingproduction per unit area by solving chronic problems of production throughbreeding high yielding, disease & pest resistant varieties, developing F1hybrids, standardisation of agro-techniques for different agro-ecologicalsituations, disease and insect pest management and post-harvest studies witha view to reduce post-harvest losses.

Twenty three vegetable namely, amaranthus, bitter kgourd, bottle gourd,brinjal, cabbaage, carrot, cauliflower, chillies, coepea, cucumbefr, Dolichos,frenchbean, garlic, Luffa, muskmelon, okra, onion, peas, pointed gourd,pumpkin, sweet pepper, tomato and watermelon have been included in thenational research programme on vegetable crops. The salient researchachievements in vegetable research.

CROP IM PROVEM ENT

(i) New Varieties Released: The evaluation of indigenous and exoticgermplasm intP> The evaluation of indigenous and exoticgermplasm introductions, and their hybridization resulted in theselection of over 30 superior varieties of different vegetables duringfiftees. Of these, varieties ‘Pusa Sawani’ of okra, ‘Pusa Ruby’ and‘Pusa Early Dwarf’ of tomaton, ‘Pusa Purple Long’ of brinjal and‘Booneville’ of garden peas still continue to be the main vegetablevarieties due to their high yield potential and consumer’s preference.As a result of multi-disciplinary, multi-location testing of newresearch materials during the last two decades, 119 improvedvarieties in 16 major vegetable crops have been identified andrecommended for cultivation in various agro-climatic regions of thecountry. These include 20 varieties of tomato, 22 of brinjal, 13 eachof onion and cauliflower, 12 of garden pea, 9 of chillies, 8 of


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muskmelon 4 each of water melon, pumpkin & okra, 3 frenchbean(bush type) 2 of garlic and 1 each of Dolichos bean, cabbage, carrot,cowpea and capsicum.It is interesting to note that out of 119 varieties recommended byAll India Coordinated vegetable Improvement Project, 52 varieties/hybrids have been released through Central Variety ReleaseCommittee for commercial cultivation in different zones of India.Moreover, the foundation and certified seeds of these varieties arebeing produced by the National Seeds Corporation Government ofIndia. Besides, 74 varieties of different of India.

(ii) F1 Hybrids Developed: In India, even though the first report of hybridvigour in chillies came in 1933 from Indian Agricultural ResearchInstitute, the first F1 hybrid of tomato and capsicum was availablefor commercial cultivation only in 1973. Since then, there has beenan increasing interest in growing hybrids in vegetable crops amongthe Indian farmers.

Heterosis breeding in vegetable crops in India has received seriousattention only in recent years. As a result the progress in developing andpopularising hybrid varieties has been very slow. The first F1 hybrid of tomato(Karnataka Hybrid) and capsaicum (Bharat) were released for commercialcultivation in 1973 by a private seed company M/s Indo-American HybridSeeds followed by 28 other Hybrids in 9 vegetable crops. Of the 21 F1 hybridsin 11 vegetable crops developed so far by public research institutions.

In addition to F1 hybrids, two synthetic cauliflower varieties, namely,‘Pusa Synthetic’ in and ‘Pusa Early Synthetic’ have also been recommendedfor release.

The F1 hybrids developed have not been fully exploited so far due toinadequate facilities for their seed production. At present there is an urgentneed to simplif production.

At present there is an urgent need to simplify the technique of hybridseed production. Various genetic mechanisms like male sterility, self-incompatibility and sgnoecious sex forms need special attention to exploitthem as female presents of the hybrids. Pioneer research work has been carriedout in the Division of Vegetable Crops, IARI, New Delhi and some femaleparents like self-incompatible lines in cauliflower and cabbage and gynoecioussex forms in muskmelon and cucumber have been developed and are beingutilized in heterosis breeding. Very good hybrid research work has beencarried out at Punjab Agricultural University on muskmelon, brinjal, tomato,chilli and onion. In general, there is acute deartrh of good hybrid seeds incauliflower, cabbnage, tomato and onion and taking up heterosis breeding inthese crops is an immediate need. Work on heterosis will be strengthenedafter the implement of NATP project.

Several private seedsmen have also been marketing hybrid vegetable


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varieties, either directly imported and rebelled or developed by crossing exoticparents and hybrid seeds produced indigenously. Some of these F1 hybridsare in tomato “Rupali”, “Vaishali”, and “Naveen” from Bangalore, “HybridS-15”, “Hybrid S-16” and “Samirudhi” from Jalna and SG-12" and SG-9" fromCalcutta; in capsicum “Bharat” from Bangalore; ‘Early Bounty’ and Sutquot;from Bangalore; ‘Early Bounty’ and Suttons Gen Gant from Calcutta; inwatermelon “Madhu and Milan” from Bangalore; in cabbage “Ganesh Gole”,“No. 8” and “Hirirani” from Jalna” in cucumber “Priya” from Bangalore. Thereare many more being offered by other seedsmen as well but their adoiptionis comparatively slow.

Disease and Pest Resistant Varieties: Research on breeding for disease/pest resistance has resulted in the release of twenty four varieties. ‘PusaSawani’ variety of okra developed as resistant to yellow-vein-mosaic virus isthe first example of successful disease resistance breeding in vegetable cropsin India.

REGIONAL CLIMATES AND VEGETATION

A forester faced with the practical problems of choosing what species toplant on a given site, or of selecting sites and species for the production of aparticular type of timber, needs a detailed knowledge of the local climatesand plant associations of his territory. This will direct him to other areas onwhich he might be able to draw for additional species. He will, of course,have made himself familiar with all available relevant experience whetherpublished or to be found in the files of the various organizations concernedwith natural history, land use, biological, geological, climatological andhydrological research in his country. He will also have studied the topography,soils and vegetation, both natural and artificial, of the tract in question and ofother parts of the country having similar conditions.

If he believes that his purpose may be served best by the trial of exoticspecies, he will obviously first consider making introductions fromhomoclimes or climatic analogues. He will turn to zones of similar andsimilarly distributed rainfall and temperatures with similar latitudes andtopography, and seek detailed information about the distribution and growththere of useful species, and the types of soil on which they grow.

These zones will be indicated somewhat vaguely on climatological mapsof the world, and more detail about them will be available in local regionalmaps and in tables of climatological data published in the regions. Then theforester can generally turn to a local flora of the region to ascertain what growsthere, and often he will be able to follow up the species which arouse hisinterest in monographs or other papers dealing with them.

If he is fortunate, he will find works such as Applied Silviculture in the


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United States and The Silviculture of Indian Trees, which will give him climatic,ecological and silvicultural information about the trees of considerable areas.Records of trials of species in different parts of the world such as are to befound in Exotic Forest Trees in the British Empire will also be useful. If he hasreason to think that some members of the genus Eucalyptus might be of valueto him, he can turn to the FAO publication Eucalypts for Planting the variousreports of the FAO Eucalyptus Study Tour (1952) and others of the 300 or sopublications listed in the bibliography of that book, and the Forest SeedDirectory, which lists 118 eucalypt species classified according to theirsuitability to grow in any of 18-climatic zones. Other Australian trees besidesthe eucalypts are included in A Reconnaissance of the Forest Trees of Australiafrom the point of view of their cultivation in South Africa.

There is, of course, nothing new about this. Horticulturists and forestershave for many years looked to countries with climates similar to their own,visited them and brought back seed of species which they thought might makepromising additions to their local floras. The only difference now is that verymuch more information is available, and that reliable seed can be obtainedfrom the zones selected without difficulty or resort to smuggling as wassometimes necessary in the past.

As an example, it may be noted that in 1823 Douglas was sent to NorthAmerica by the Royal Horticultural Society of London because it was realizedthat the Pacific Coast region was the home of a particularly rich flora growingin a climate comparable to some parts of the British Isles. This region fromOregon northwards through Washington and British Columbia to southeastAlaska and bounded on the east by the Coastal Ranges contains a far widerrange of climate than does Britain, but the temperature regime at the mouthof the Columbia River around latitude 46° N., with an average in summer of54° F. (13° C.) and an average for the year of 50° F. (11° C.), is similar to thatof the English south coast, latitude about 50.5° N.; and Sitka in Alaska, latitude57° N., closely matches the northwest coast of Scotland. The rainfall on thePacific coast is of the winter type with midsummer the driest period, whereasin Britain spring is relatively dry. Further north up the coast the proportionof rain falling in the summer is greater, until in southeast Alaska it is close tothe 22 percent commonly found in Britain. Inland, the climate becomes rapidlycontinental and summer temperatures are higher than in England.

The trees of the region important to forestry in Britain and parts of westernEurope have been found to be Sitka spruce, Douglas fir, Pinus contorta Dougl.,Abies grandis Indl., Tsuga heterophylla Sarg. and Thuya plicata Don. All penetrateinto climates of much lower winter temperature than are found in Britain,and Douglas fir and the Abies than those of Britain, in particular grow best inwarmer summer temperatures averaging 52° to 56° F. (11.1°-13.3°C.) thoughthere is no reason to suppose that they are limited by summer temperature.In their native habitat, neither Douglas fir nor Sitka spruce appear to form


16

part of climax forest communities, but are pioneer species giving way toTsuga, Thuya and Abies. Sitka spruce thrives at low elevations in the BritishColumbian region with mean annual temperatures varying from 44° to 49° F.(6.7°-9.4°C.), summer mean of 55° to 68°F. (12.8°-20°C.), winter mean of 30°to 38° F. (1.1°-3.3° C.) and a rainfall of 40 inches (1,020 mm.) a year upwards,conditions which can easily be matched in Britain.

It is now possible to buy from government forest departments and frommerchants seed certified as collected from known climatic and elevationalzones in this region as from several other regions of the world. The forms ofagreed international certificates of origin and quality, and the sources fromwhich a large number of species can be obtained. One firm divides itscollection area on the Pacific coast from Alaska to California into 25 climaticregions, subdivided into 127 zones, each of which is further split up into 500foot (150 m.) elevation bands. It provides tables which give the temperatures(average annual, average summer, absolute maximum and absoluteminimum), precipitation (annual and summer), and the number of frost-freedays in the year, for the most representative weather station in each zone.

Another country which was drawn on early for plantation species wasAustralia. In 1843, several species of eucalypt were tried in the Nilgiri Hillsof India, and later Eucalyptus globulus Labill. solved a serious fuel shortagethere. In 1870, Acacia mollissima Willd was introduced into Natal and easternTransvaal in South Africa and by 1952 a great tanbark industry dependingon some 640,000 acres (259,000 ha.) of black wattle plantations had been builtup. In 1876, Eucalyptus saligna Sm. was first planted for railway fuel in SouthAfrica, and now there are some 200,000 acres (80,000 ha.) of it in eastern andnorthern Transvaal and on the Zululand coast. Early in the present century,the Companhia Paulista de Estradas de Ferro, the State railway of Sao Paulo,Brazil, imported 143 species of eucalypts and now has some 30,000 acres(12,000 ha.) of plantations, mainly of E. camaldulensis Dahn., E. citriodora Hookand E. saligna. The Mediterranean countries, Spain, Portugal, France, Italy andGreece, have all found E. globulus and E. camaldulensis valuable additions totheir plantation species. In California, 80 percent of the considerable eucalyptplantations are of E. globulus, and 15 percent of E. camaldulensis. Peru, Chileand Uruguay all make considerable use of E. globulus, while in Turkey, Cyprus,Palestine, Jordan, Tripolitania and Morocco the most popular eucalypt is E.Camaldulensis. Many other species are found to be suitable to particular partsof these and many other countries.

It is, therefore, worth considering the climate and vegetation of theAustralian continent. Australia has a central desert zone covering nearly 40percent of its whole area, and the rest can be divided very roughly into threemain climatic zones:

1. A tropical northern zone of summer rainfall, north of about 20° S.on the west coast and about 14° S. on the east coast. The mean


17

annual rainfall varies from about 20 inches (510 mm.) in the southof the zone to 60) inches (1,525 mm.) and more on the north andeast coasts, with some areas receiving 120 inches (3,050 mm.). Themean annual temperature is in the neighborhood of 80° F. (26.4°C.), the interior being warmer than the coastal areas and the westcoast warmer than the east.

2. A zone of moderate winter rainfall and dry summers in the southernparts of South Australia, Western Australia, the greater part ofVictoria, and the south of New South Wales. Mean annual rainfallvaries from about 10 inches (250 mm.) to about 30 inches (760 mm.)with isolated areas of up to 40 inches (1,020 mm.) on the southcoast. Summer temperatures are around 70° F. (21.1° C.) and wintertemperatures around 35° F. (1.7° C.)

3. A zone of more uniformly distributed rainfall on the east coast andthe southeastern part of the continent with annual rainfall generallybetween 20 inches (510 mm.) and 60 inches (1,526 mm.). This zoneincludes the mountains of New South Wales, and there and on theeast coast the rainfall is from 40 to 60 inches (1,020-1,526 mm.) ayear, with isolated areas of 120 inches (3,050 mm.) on the coast ofnorthern Queensland, where the summer is the wetter season. Inthe south (Victoria), there is a tendency towards a maximum rainfallin winter. In New South Wales, the even distribution is morenoticeable, though in the north and on the east coast more rainfalls in summer, and on the south coast more in winter. There arevery considerable variations in temperature regimes within the zone,because of the topography.

De Beuzville (1943) considered that the whole of the east coast of Australiahas a climate predominantly similar to that of Argentine, Brazil and Mexicoand certain parts of South Africa, and also, in its wetter parts, in Madagascar.The north coast and its hinterland has a climate similar to those of parts ofMadagascar, India and Mozambique. On the west coast and inland from itthere are stations with climates similar to some found in South Africa, Algeria,Sudan, Mexico and Arizona. The climate in the south southwest is more likethat of California and South Africa, and in small areas like that of Spain. TheAustralian Alps and the Dividing Range have cool slopes where the climateapproximates to that of France and Italy. The dry centre of Australia has aclimate similar to that of Egypt, Arizona, Israel and parts of the Californiandesert. Robertson (1926) found that, while coastal temperatures, latitude forlatitude, were very similar in Australia and South Africa, the interior ofAustralia was warmer than that of South Africa because of the greaterelevation of the latter.

The forest formations of Australia may be roughly divided into RainForest (tropical, sub-tropical, and temperate), Moist Sclerophyllous Forest, pry


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Sclerophyllous Forest, and Open Woodland, all of which merge into eachother.

The rain forests occur only in isolated relict patches. In the tropical zonetheir flora is Malayan without predominant species, and the natural successionis very confused.

From the Hastings River, about 30° S., in New South Wales to the northof Queensland, Araucaria cunninghammii Ait is found on the coast and up to100 miles (160 km.) inland with an annual rainfall of 50 to 70 inches(1,270-1,780 mm.), falling mainly in summer. Araucaria bidwillii Hock, andAgathis robusta are found in southeast Queensland in areas with50-60 inches (1,270-1,525 mm.) summer rain, with summer temperatures of75° to 85° F. (24°-29° C.) and winter temperatures of 50° to 60° F. (10°-16° C.).What are apparently secondary forest formation after fires include Tristaniaconferta R. Br. and Syncarpia laurifolia Ten. mixed with eucalypts such asEucalyptus saligna.

The sclerophyllous formations are mainly composed of eucalypts andacacias. Closed stands of Eucalyptus are not usually found where the rainfallis less than 30 inches (760 mm.) a year, below which limit open and scrubbyvegetation occurs.

Many of the eucalypt species are confined to particular zones of rainfallamount and distribution, but some are very adaptable. One of the most widelydistributed is E. camaldulensis which Boosman (1950) states can put up with 5to 10 inches (130-250 mm.) of rain a year, is often found in zones of 22 to 28inches (560-710 mm.), and exceptionally with 40 to 45 inches (1,020-1,140 mm.)though 35 inches (890 mm.) is regarded as its normal maximum. Actually itsrange is determined more by soil moisture conditions than by precipitationand it is characteristic of alluvial flats, often along river banks where water isavailable by inundation or percolation.

It likes warmth and extends into some of the hottest parts of the NorthernTerritory. It is not found in the highlands of New South Wales in which Statede Beuzville (1943) gives a mean temperature of the coldest month of 46° F.(7.8° C.) as the lower thermal limit of its range. It must be remembered thatthe form, as well as the stand density, of eucalypt species growing in areas oftheir minimum rainfall is very different from what it is under optimumrainfall.

Moist sclerophyllous forest is found mainly in the southeastern coastalstrip of New South Wales and Victoria, and in the southwest corner of WesternAustralia, in the zones of either winter or fairly uniform rainfall. In WesternAustralia, Eucalyptus diversi-colour F. V. M. is found in stands of a typeapproaching temperate rainforest in a climate of 40 to 60 inches (1,020-1,525mm.) mean annual rainfall and mean annual temperatures of 62° to 65° F.(16.7°-18.6° C.) In Victoria and New South Wales, Eucalyptus globulus growsin the higher and cooler sites with 35 to 65 inches (890-1,650 mm.) of rain and


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mean annual temperatures of 44° to 49° F. (6.7°-9.4° C.) sometimes mixedwith Acacia melanoxylon R. Br. and with an understorey of Acacia mollissimaWild. or A. dealbata Link. In the wetter range of these sites in Victoria, standsof Eucalyptus regnas F. v. M. are found.

Eucatyptus gomphocephala A. Dc. with an undergrowth of Acacia cyanophyllaLindl. is found growing on calcareous sands in the southwest of WesternAustralia in an annual rainfall of 30 to 40 inches (760-1,020 mm.) mainly inwinter, with an annual mean temperature of 60° to 64° F. (15.6°-17.8° C.) anda summer temperature of 67° to 72° F. (19.4°-22.2° C.). There are either nofrosts or only occasional light ones in places. Both species have proved valuablein the afforestation of coastal sand in South Africa, and more recently haveshown considerable promise when used in combination on calcareous sanddunes in Morocco.

In the dry sclerophyllous forests there is a very great variety of eucalyptspecies, not many of which attain timber dimensions in the lower rainfall areas.In New South Wales and Queensland, Eucalypts crebra F. V. M. grows with arainfall of 20 to 26 inches (510-660 mm.) a year mainly in summer in areas ofhigh temperature, often mixed with Callitris glauca R. Br. Eucalypts sideroxylonA. Cunn. is found in poor sites in New South Wales, Victoria and Queenslandwith about 20 inches (510 mm.) of rain a year.

There are also species which are characteristic of moister forests butnevertheless can grow with as little as 22 to 25 inches (560-635 mm.) a year,such as Eucalypts marginata Sm. in Western Australia, and E. oblique l’Herit. inSouth Australia, Victoria and New South Wales. Where there is moistureenough to permit of under this is often Acacia pycnantha or A. mollissima inthe east, and A. cyanophylla or A. cyclops Cunn. in the west.

These formations merge into open woodland, particularly in westernQueensland and New South Wales. Eucalypts salmonophloia F. V. M. grow inWestern Australia in the zone of 9 to 12 inches (220-305 mm.) of rain, mainlyfrom June to September. ‘Mallee’ formations consisting of a great variety ofsmall, often bush-like, eucalypts attaining up to 20 feet (6 m.) in height withstems of 3 to 6 inches (7.6-15.2 cm.) in diameter, cover considerable areas oflow rainfall.

South Africa is a good example of a country with inadequate naturalforests and slow-growing indigenous species. The need to supplement thenatural flora was recognized early. Conifers and hardwoods were importedfrom northern Europe from 1665, but did not thrive. Later some Mediterraneanspecies, notably Pinus pinea L., which became naturalized in the CapePeninsula, and Pinus pinaster Sol., which has been widely planted and doesbest in the zone with winter or all-the-year-round rainfall, were introduced.By the middle of the nineteenth century P. radiata had been brought fromCalifornia and had proved to be very adaptable in climates similar to thosefavoured by P. pinaster, though more particular about soil. Later in the century,


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P. longifolia Roxb. was introduced from the outer ranges of the Himalayas inIndia and proved useful in the cool and warm temperate summer rainfallareas. A great step forward was made about 1905 when Hutchins decidedthat Mexico, a plateau country like the Transvaal, lying in approximatelysimilar latitudes, having a summer rainfall and a rich flora, should be apromising source of exotics. He tried a number of species including Pinuspatula Seem. of which there is now a bigger acreage in South Africa that ofany other softwood, particularly, of course, in the summer rainfall areas.Hutchins also recommended P. caribaea Morelet from the southern UnitedStates of America for the sub-tropical zone, and it has shown exceptionallyvigorous growth in both the temperate and sub-tropical zones with winter orall-the-year-round rainfall.

It is being planted on a large scale for paper pulp in Zululand. By 1947,some nervousness was felt about the dangers of disease in large pure blocksof these two species and an officer was sent to America to study the pines intheir natural habitats and to find additional species if possible. He wasparticularly interested in Pinus pseudostrobus Lind. which had originally beentried under the name of P. teocote Schl. v Cham. with success, but the seed ofwhich could not be obtained. He was able to collect 350 pounds (159 kg.) ofseed in Mexico.

He was also impressed by Pinus hondurensia Loock in British Honduras,only lately distinguished from P. caribaea. This illustrates the importance ofbotanical identification and of securing seed of the most suitable species andvarieties for use in particular localities. Where reliable local agencies for thesupply of seed do not exist it may be necessary to go and collect exactly whatis wanted.

These conifers and others from California, Central America, India, theMediterranean region, and Mexico now cover more than 600,000 acres (243,000ha.) of South Africa, alongside some 640,000 acres (259,000 ha.) of acacias and450,000 acres (186,000 ha.) of eucalypts from Australia, an example of whatcan be done by selection and trial of species from climates similar to those inwhich they are required to grow.

Reference is made earlier, in the study of which this chapter is an exerpt,to the agro-climatic analogues established at the American Institute of CropEcology by Nuttonson (1937-53). Up to the latter year analogues had beenestablished between North America and Ukraine, Poland, Czechoslovakia,Yugoslavia, Greece Albania, China, Germany, Finland Sweden, Norway,Siberia, Japan, and the Ryukyu Islands. Each of these studies gives a generaland comparative geography of the country covered and a brief account of itsclimate. There is also a varying amount of information about the naturalresources of the country, its soils, major plant species, land-use, agriculturaland forestry practices, etc. Relief maps show the location of the meteorologicalstations within the country studied and the regions of any North American


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climatic counterparts found. Charts give full meterological data for each stationand for the counterparts.

The purpose of this series of studies is “to formulate an agronomic andhorticultural approach to ecology and to promote research along the lines ofcrop ecology as it affects plant adaptation, plant introduction, and the exchangeof varietal plant material among the various agricultural areas of the worlds”.Its value is not, however, confined to agriculturists. For instance, the paperon Japan (1951) points out:

“Over one half of the total land area of the country is covered withluxuriant forests of a great diversify of broadleaved and coniferous speciesand of dense undergrowth. These forests are found largely in the mountainousregions, as more than three-fourths of the country’s land consists of roughand rugged mountains and hills topographically unsuitable for cultivation offarm crops.”


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2

Significance of Fruit andVegetables

FRUIT AND VEGETABLE PROCESSING ACTIVITIES

In developing countries agriculture is the mainstay of the economy. Assuch, it should be no surprise that agricultural industries and related activitiescan account for a considerable proportion of their output. Of the various typesof activities that can be termed as agriculturally based, fruit and vegetableprocessing are among the most important. Both established and planned fruitand vegetable processing projects aim at solving a very clearly identifieddevelopment problem. This is that due to insufficient demand, weak infrastructure,poor transportation and perishable nature of the crops, the grower sustainssubstantial losses. During the post-harvest glut, the loss is considerable andoften some of the produce has to be fed to animals or allowed to rot.

Even established fruit and vegetable canning factories or small/mediumscale processing centres suffer huge loss due to erratic supplies. The growermay like to sell his produce in the open market directly to the consumer, orthe produce may not be of high enough quality to process even though itmight be good enough for the table. This means that processing capacitieswill be seriously underexploited. The main objective of fruit and vegetableprocessing is to supply wholesome, safe, nutritious and acceptable food toconsumers throughout the year. Fruit and vegetable processing projects alsoaim to replace imported products like squash, yams, tomato sauces, pickles,etc., besides earning foreign exchange by exporting finished or semi-processedproducts.

The fruit and vegetable processing activities have been set up, or have tobe established in developing countries for one or other of the followingreasons:

• Diversification of the economy, in order to reduce presentdependence on one export commodity;

• Government industrialisation policy;• Reduction of imports and meeting export demands;• Stimulate agricultural production by obtaining marketable products;• Generate both rural and urban employment;• Reduce fruit and vegetable losses;• Improve farmers’ nutrition by allowing them to consume their own

processed fruit and vegetables during the off-season;• Generate new sources of income for farmers/artisans;• Develop new value-added products.

FRUIT AND VEGETABLES REPRESENT AN IM PORTANTPART OF WORLD AGRICULT URE

Fruit and vegetables represent an important part of world agricultureproduction; some figures are seen in Table given below.

Table: Fruit and Vegetable World Production, 1991

Crop (Fruit) Production, 1000 T Dev.ping

Total World all

Appies 39404 14847

Apricots 2224 1147

Avocados 2036 1757

Bananas 47660 46753

Citrus fruits NES 1622 1231

Cantaloupes and other melons 12182 8733

Dates 3192 3146

Grapes 57188 14257

Grapefruit and pomelo 4655 2073

Lemons and limes 6786 4457

Mangoes 16127 16075

Oranges 55308 40325

Peaches and nectarines 8682 2684

Pears 9359 4431

Papayas 4265 4205

Plantains 26847 26847

Plums 5651 1806

Pineapples 10076 9183

Raisins 1041 470

Tangerines, mandarines, clementines 8951 4379

Watermelons 28943 19038

Currants 536009 Raspberries 369087 Strawberries 2469117 342009

Beans, green 3213 1702


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Cabbages 36649 15569

Cauliflower 5258 2269

Carrots 13511 4545

Chilies + peppers, green 9145 6440

Cucumbers and gherkins 13619 7931

Eggplants 5797 4608

Garlic 3102 2446

Onions, dry 27977 17128

Peas, green 4856 1038

Pumpkins, squash, gourds 7933 6245

FRUIT AND VEGETABLES CAN BE PROCESSED

Practically any fruit and vegetable can be processed, but some importantfactors which determine whether it is worthwhile are:

a. The demand for a particular fruit or vegetable in the processed form;b. The quality of the raw material, i.e. whether it can withstand

processing;c. Regular supplies of the raw material.For example, a particular variety of fruit which may be excellent to eat

fresh is not necessarily good for processing. Processing requires frequenthandling, high temperature and pressure.

Many of the ordinary table varieties of tomatoes, for instance, are notsuitable for making paste or other processed products. A particular mangoor pineapple may be very tasty eaten fresh, but when it goes to the processingcentre it may fail to stand up to the processing requirements due to variationsin its quality, size, maturity, variety and so on.

Even when a variety can be processed, it is not suitable unless large andregular supplies are made available. An important processing centre or afactory cannot be planned just to rely on seasonal gluts; although it can takecare of the gluts it will not run economically unless regular supplies areguaranteed. To operate a fruit and vegetable processing centre efficiently it isof utmost importance to pre-organise growth, collection and transport ofsuitable raw material, either on the nucleus farm basis or using outgrowers.

Fruit and Vegetable Processing Planning

The secret of a well planned fruit and vegetable processing centre is thatit must be designed to operate for as many months of the year as possible.This means the facilities, the buildings, the material handling and theequipment itself must be inter-linked and coordinated properly to allow asmany products as possible to be handled at the same time, and yet theequipment must be versatile enough to be able to handle many productswithout major alterations.

A typical processing centre or factory should process four or five types


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of fruits harvested at different times of the year and two or three vegetables.This processing unit must also be capable of handling dried/dehydratedfinished products, juices, pickles, tomato juice, ketchup and paste, jams, jelliesand marmalades, semi-processed fruit products.

Advanced planning is necessary to process a large range of products invaried weather and temperature conditions, each requiring a special set ofmanufacturing and packaging formulae. The end result of the efforts shouldbe a well-managed processing unit with lower initial investment.

A unit which is sensibly laid out and where one requirement co-relatesto another, with a sound costing analysis, leads to an integrated operation.Instead of over-sophisticated machinery, a sensible simple processing unitmay be required when planned production is not very large and is gearedmainly to meet the demand of the domestic market.

Basic Objective and Choose the Location

The basic objective is to choose the location which minimises the averageproduction cost, including transport and handling. It is an advantage, all otherthings being equal, to locate a processing unit near the fresh raw materialsupply. It is a necessity for proper handling of the perishable raw materials,it allows the processing unit to allow the product to reach its best stage ofmaturation and lessens injury from handling and deterioration from changesduring long transportation after harvesting.

An adequate supply of good water, availability of manpower, proximityto rail or road transport facilities and adequate markets are other importantrequirements.

Processing Systems

a. Small-Scale Processing. This is done by small-scale farmers forpersonal subsistence or for sale in nearby markets. In this system,processing requires little investment: however, it is time consumingand tedious. Until recently, small-scale processing satisfied the needsof rural and urban populations. However, with the rising rates ofpopulation and urbanisation growth and their more diversified fooddemands, there is need for more processed and diversified typesof food.

b. Intermediate-Scale Processing. In this scale of processing, a groupof small-scale processors pool their resources. This can also be doneby individuals. Processing is based on the technology used by small-scale processors with differences in the type and capacity ofequipment used. The raw materials are usually grown by theprocessors themselves or are purchased on contract from otherfarmers. These operations are usually located on the productionsite of in order to assure raw materials availability and reduce cost


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of transport. This system of processing can provide quantities ofprocessed products to urban areas.

c. Large-Scale Processing. Processing in this system is highlymechanised and requires a substantial supply of raw materials foreconomical operation. This system requires a large capitalinvestment and high technical and managerial skills. Because of thehigh demand for foods in recent years many large-scale factorieswere established in developing countries. Some succeeded, but themajority failed, especially in West Africa. Most of the failures wererelated to high labour inputs and relatively high cost, lack ofmanagerial skills, high cost and supply instability of raw materialsand changing governmental policies. Perhaps the most importantreason for failure was lack of adequate quantity and regularity ofraw material supply to factories. Despite the failure of thesecommercial operations, they should be able to succeed with betterplanning and management, along with the undertaking of more in-depth feasibility studies.

It can be concluded that all three types of processing systems have a placein developing countries to complement crop production to meet food demand.Historically, however, small and intermediate scale processing proved to bemore successful than large-scale processing in developing countries.

CHOICE OF PROCESSING TECHNOLOGIES FOR

DEVELOPING COUNTRIES

FAO maintains, that the basis for choosing a processing technology fordeveloping countries ought to be to combine labour, material resources andcapital so that not only the type and quantity of goods and services producedare taken into account, but also the distribution of their benefits and theprospects of overall growth.

These should include:a. Increasing farmer/artisan income by the full utilisation of available

indigenous raw material and local manufacturing of part or allprocessing equipment;

b. Cutting production costs by better utilisation of local naturalresources (solar energy) and reducing transport costs;

c. Generating and distributing income by decentralising processingactivities and involving different beneficiaries in processing activities(investors, newly employed, farmers and small-scale industry);

d. Maximising national output by reducing capital expenditure androyalty payments, more effectively developing balance-of-paymentsdeficits through minimising imports (equipment, packing material,


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additives), and maximising export-oriented production;e. Maximising availability of consumer goods by maximisation of

high-quality, standard processed produce for internal and exportmarkets, reducing post-harvest losses, giving added value toindigenous crops and increasing the volume and quality ofagricultural output.

Knowledge and control of the means of production, local manufacturingof processing equipment and development of appropriate/new technologiesand more suitable raw material for processing must all be betterresearched. Decentralisation of activities must be maintained and coordinated.The introduction of more sophisticated processing equipment and packagingmaterial must be subordinated to internal and export marketing references.

Choosing a technology solely to maximise profits can actually workagainst true development. Choice should also be based on a solid, long-termmarket opportunity to ensure viability. The internal market should be givengreater consideration, safeguarded and supported. Training courses, at alllevels, in processing and preservation of indigenous crops, must be expanded.

GLOBAL M ARKET ING VIEW OF FRUIT AND VEGETABLES

Fruit and vegetables have many similarities with respect to theircompositions, methods of cultivation and harvesting, storage properties andprocessing. In fact, many vegetables may be considered fruit in the truebotanical sense. Botanically, fruits are those portions of the plant which houseseeds. Therefore such items as tomatoes, cucumbers, eggplant, peppers, andothers would be classified as fruits on this basis.However, the importantdistinction between fruit and vegetables has come to be made on an usagebasis. Those plant items that are generally eaten with the main course of ameal are considered to be vegetables. Those that are commonly eaten as dessertare considered fruits. That is the distinction made by the food processor,certain marketing laws and the consuming public, and this distinction willbe followed in this document.

Fruit as a dessert item, is the mature ovaries of plants with their seeds.The edible portion of most fruit is the fleshy part of the pericarp or vesselsurrounding the seeds. Fruit in general is acidic and sugary. They commonlyare grouped into several major divisions, depending principally uponbotanical structure, chemical composition and climatic requirements.

Berries are fruit which are generally small and quite fragile. Grapes arealso physically fragile and grow in clusters. Melons, on the other hand, arelarge and have a tough outer rind. Drupes (stone fruit) contain single pitsand include such items as apricots, cherries, peaches and plums. Pomes containmany pits, and are represented by apples, quince and pears.

Vegetables are derived from various parts of plants and it is sometimesuseful to associate different vegetables with the parts of the plant they


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represent since this provides clues to some of the characteristics we may expectin these items. A classification of vegetables based on morphological featuresis seen in Table given below.

Table: Classification of Vegetables

Category Examples

Earth vegetables roots sweet potatoes, carrots

modified stems tubers potatoes

modified buds bulbs onions, garlic

Herbage vegetables leaves cabbage, spinach, lettuce

petioles (leaf stalk) celery, rhubarb

flower buds cauliflower, artichokes

sprouts, shoots (young stems) asparagus, bamboo shoots

Fruit vegetables legumes peas, green beans

cereals sweet corn

vine fruits squash, cucumber

berry fruits tomato, egg plant

tree fruits avocado, breadfruit

Citrus fruit like oranges, grapefruit and lemons are high in citric acid.Tropical and subtropical fruits include bananas, dates, figs, pineapples,mangoes, and others which require warm climates, but exclude the separategroup of citrus fruits. The compositions of representative vegetables and fruitsin comparison with a few of the cereal grains are seen in Table given below.

Table: Typical Percentage Composition of Foods from Plant Origin Percentage

Composition-Edible Portion

Food Carbohydrate Protein Fat Ash Water

Cereals

wheat flour, white 73.9 10.5 1.9 1.7 12

rice, milled, white 78.9 6.7 0.7 0.7 13

maize, whole grain 72.9 9.5 4.3 1.3 12

Earth vegetables

potatoes, white 18.9 2.0 0.1 1.0 78

sweet potatoes 27.3 1.3 0.4 1.0 70

Vegetables carrots 9.1 1.1 0.2 1.0 88.6

radishes 4.2 1.1 0.1 0.9 93.7

asparagus 4.1 2.1 0.2 0.7 92.9

beans, snap, green 7.6 2.4 0.2 0.7 89.1

peas, fresh 17.0 6.7 0.4 0.9 75.0

lettuce 2.8 1.3 0.2 0.9 94.8

Fruit

banana 24.0 1.3 0.4 0.8 73.5


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orange 11.3 0.9 0.2 0.5 87.1

apple 15.0 0.3 0.4 0.3 84.0

strawberries 8.3 0.8 0.5 0.5 89.9

Compositions of vegetables and fruit not only vary for a given kind inaccording to botanical variety, cultivation practices, and weather, but changewith the degree of maturity prior to harvest, and the condition of ripeness,which is progressive after harvest and is further influenced by storageconditions. Nevertheless, some generalisations can be made.

Most fresh vegetables and fruit are high in water content, low in protein,and low in fat. In these cases water contents will generally be greater than70% and frequently greater than 85%. Commonly protein content will not begreater than 3.5% or fat content greater than 0.5 %. Exceptions exist in thecase of dates and raisins which are substantially lower in moisture but cannotbe considered fresh in the same sense as other fruit.

Legumes such as peas and certain beans are higher in protein; a fewvegetables such as sweet corn which are slightly higher in fat and avocadoswhich are substantially higher in fat. Vegetables and fruit are importantsources of both digestible and indigestible carbohydrates. The digestiblecarbohydrates are present largely in the form of sugars and starches whileindigestible cellulose provides roughage which is important to normaldigestion.

Fruit and vegetables are also important sources of minerals and certainvitamins, especially vitamins A and C. The precursors of vitamin A, includingbeta-carotene and certain other carotenoids, are to be found particularly inthe yellow-orange fruit and vegetables and in the green leafy vegetables.

Citrus fruit are excellent sources of vitamin C, as are green leafy vegetablesand tomatoes. Potatoes also provide an important source of vitamin C for thediets of many countries. This is not so much due to the level of vitamin C inpotatoes which is not especially high but rather to the large quantities ofpotatoes consumed.

VEGETAL CELLS CONTAIN IMPORTANT QUANTITIES OF WATER

WAT ER

Vegetal cells contain important quantities of water. Water plays a vitalrole in the evolution and reproduction cycle and in physiological processes.It has effects on the storage period length and on the consumption of tissuereserve substances.

In vegetal cells, water is present in following forms:• Bound water or dilution water which is present in the cell and forms

true solutions with mineral or organic substances;• Colloidal bound water which is present in the membrane, cytoplasm


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and nucleus and acts as a swelling agent for these colloidal structuresubstances; it is very difficult to remove during drying/dehydrationprocesses;

• Constitution water, directly bound on the chemical componentmolecules and which is also removed with difficulty.

Vegetables contain generally 90-96% water while for fruit normal watercontent is between 80 and 90%.

CARBOHYDRAT ES

Carbohydrates are the main component of fruit and vegetables andrepresent more than 90% of their dry matter. From an energy point of viewcarbohydrates represent the most valuable of the food components; daily adultintake should contain about 500 g carbohydrates. Carbohydrates play a majorrole in biological systems and in foods. They are produced by the process ofphotosynthesis in green plants. They may serve as structural components asin the case of cellulose; they may be stored as energy reserves as in the case ofstarch in plants; they may function as essential components of nucleic acidsas in the case of ribose; and as components of vitamins such as ribose andriboflavin. Carbohydrates can be oxidised to furnish energy, and glucose inthe blood is a ready source of energy for the human body. Fermentation ofcarbohydrates by yeast and other microorganisms can yield carbon dioxide,alcohol, organic acids and other compounds.

Some Properties of Sugars

Sugars such as glucose, fructose, maltose and sucrose all share thefollowing characteristics in varying degrees, related to fruit and vegetabletechnology:

• They supply energy for nutrition;• They are readily fermented by micro-organisms;• In high concentrations they prevent the growth of micro-organisms,

so they may be used as a preservative;• On heating they darken in colour or caramelise;• Some of them combine with proteins to give dark colours known

as the browning reaction.Some properties of starches:• They provide a reserve energy source in plants and supply energy

in nutrition;• They occur in seeds and tubers as characteristic starch granules.Some properties of celluloses and hemicelluloses:• They are abundant in the plant kingdom and act primarily as

supporting structures in the plant tissues;• They are insoluble in cold and hot water;• They are not digested by man and so do not yield energy for


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nutrition;• The fibre in food which produces necessary roughage is largely

cellulose.Some properties of pectins and carbohydrate gums:• Pectins are common in fruits and vegetables and are gum-like (they

are found in and between cell walls) and help hold the plant cellstogether;

• Pectins in colloidal solution contribute to viscosity of the tomatopaste;

• Pectins in solution form gels when sugar and acid are added; thisis the basis of jelly manufacture.

M INERAL SUBSTANCES

Mineral substances are present as salts of organic or inorganic acids oras complex organic combinations (chlorophyll, lecithin, etc.); they are in manycases dissolved in cellular juice. Vegetables are more rich in mineral substancesas compared with fruits. The mineral substance content is normally between0.60 and 1.80% and more than 60 elements are present; the major elementsare: K, Na, Ca, Mg, Fe, Mn, Al, P. Cl, S.

Among the vegetables which are especially rich in mineral substancesare: spinach, carrots, cabbage and tomatoes. Mineral rich fruit includes:strawberries, cherries, peaches and raspberries. Important quantities ofpotassium (K) and absence of sodium chloride (NaCl) give a high dieteticvalue to fruit and to their processed products. Phosphorus is supplied mainlyby vegetables. Vegetables usually contain more calcium than fruit; greenbeans, cabbage, onions and beans contain more than 0.1% calcium. Thecalcium/phosphorus or Ca/P ratio is essential for calcium fixation in the humanbody; this value is considered normal at 0.7 for adults and at 1.0 for children.Some fruit are important for their Ca/P ratio above 1.0: pears, lemons, orangesand some temperate climate mountain fruits and wild berries.

Even if its content in the human body is very low, iron (Fe) has animportant role as a constituent of haemoglobin. Main iron sources are applesand spinach. Salts from fruit have a basic reaction; for this reason fruitconsumption facilitates the neutralisation of noxious uric acid reactions andcontributes to the acid-basic equilibrium in the blood.

Fats

Generally fruit and vegetables contain very low level of fats, below 0.5%.However, significant quantities are found in nuts (55%), apricot kernel (40%),grapes seeds (16%), apple seeds (20%) and tomato seeds (18%).

Organic Acids

Fruit contains natural acids, such as citric acid in oranges and lemons,


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malic acid of apples, and tartaric acid of grapes. These acids give the fruitstartness and slow down bacterial spoilage. We deliberately ferment some foodswith desirable bacteria to produce acids and this give the food flavour andkeeping quality. Examples are fermentation of cabbage to produce lactic acidand yield sauerkraut and fermentation of apple juice to produce first alcoholand then acetic acid to obtain vinegar. Organic acids influence the colour offoods since many plant pigments are natural pH indicators.

With respect to bacterial spoilage, a most important contribution oforganic acids is in lowering a food’s pH. Under anaerobic conditions andslightly above a pH of 4.6, Clostridium botulinum can grow and produce lethaltoxins. This hazard is absent from foods high in organic acids resulting in apH of 4.6 and less.

Acidity and sugars are two main elements which determine the taste offruit. The sugar/acid ratio is very often used in order to give a technologicalcharacterisation of fruits and of some vegetables.

NIT ROGEN-CONTAINING SUBSTANCES

These substances are found in plants as different combinations: proteins,amino acids, amides, amines, nitrates, etc. Vegetables contain between 1.0 and5.5 % while in fruit nitrogen-containing substances are less than 1% in mostcases. Among nitrogen containing substances the most important are proteins;they have a colloidal structure and, by heating, their water solution above50°C an one-way reaction makes them insoluble. This behaviour has to betaken into account in heat processing of fruits and vegetables. From a biologicalpoint of view vegetal proteins are less valuable then animal ones because intheir composition all essential amino-acids are not present.

Enzymes

Enzymes are biological catalysts that promote most of the biochemicalreactions which occur in vegetable cells.

Some properties of enzymes important in fruit and vegetable technologyare the following:

• In living fruit and vegetables enzymes control the reactionsassociated with ripening;

• After harvest, unless destroyed by heat, chemicals or some othermeans, enzymes continue the ripening process, in many cases tothe point of spoilage - such as soft melons or overripe bananas;

• Because enzymes enter into a vast number of biochemical reactionsin fruits and vegetable, they may be responsible for changes inflavour, colour, texture and nutritional properties;

• the heating processes in fruit and vegetables manufacturing/processing are designed not only to destroy micro-organisms butalso to deactivate enzymes and so improve the fruit and vegetables’


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storage stability.Enzymes have an optimal temperature - around +50°C where their activity

is at maximum. Heating beyond this optimal temperature deactivates theenzyme. Activity of each enzyme is also characterised by an optimal pH.

In fruit and vegetable storage and processing the most important rolesare played by the enzymes classes of hydrolases (lipase, invertase, tannase,chlorophylase, amylase, cellulase) and oxidoreductases (peroxidase,tyrosinase, catalase, ascorbinase, polyphenoloxidase).

T URGIDIT Y AND T EXT URE

The range of textures that are encountered in fresh and cooked vegetablesand fruit is indeed great, and to a large extent can be explained in terms ofchanges in specific cellular components. Since plants tissues generally containmore than two-thirds water, the relationships between these components andwater further determine textural differences.

Cell Turgidity

Quite apart from other contributing factors, the state of turgidity,determined by osmotic forces, plays a paramount role in the texture of fruitand vegetables. The cell walls of plant tissues have varying degrees of elasticityand are largely permeable to water and ions as well as to small molecules.

The membranes of the living protoplast are semi-permeable, that is theyallow passage of water but are selective with respect to transfer of dissolvedand suspended materials.

The cell vacuoles contain most of the water in plant cells and sugars, acids,salts, amino acids, some water-soluble pigments and vitamins, and other lowmolecular weight constituents are dissolved in this water.

In the living plant, water taken up by the roots passes through the cellwalls and membranes into the cytoplasm of the protoplasts and into thevacuoles to establish a state of osmotic equilibrium within the cells.

The osmotic pressure within the cell vacuoles and within the protoplastspushes the protoplasts against the cell walls and causes them to stretch slightlyin accordance with their elastic properties. This is the situation in the growingplant and the harvested live fruit or vegetable which is responsible for desiredplumpness, succulence, and much of the crispness.

When plant tissues are damaged or killed by storage, freezing, cooking,or other causes, an important major change that results is denaturation of theproteins of cell membranes resulting in the loss of perm-selectivity. Withoutperm-selectivity the state of osmotic pressure in cell vacuoles and protoplastscannot exist, and water and dissolved substances are free to diffuse out of thecells and leave the remaining tissue in a soft and wilted condition.

Other Factors Affecting Texture

The existence of a high degree of turgidity in live fruit and vegetables or


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whether a relative state of flabbiness develops from loss of osmotic pressureas well as final texture depends on several cell constituents.

Cellulose, Hemicellulose, and Lignin

Cell walls in young plants are very thin and are composed largely ofcellulose. As the plant ages cell walls tend to thicken and become higher inhemicellulose and in lignin. These materials are fibrous and tough and arenot significantly softened by cooking.

Pectic Substances

The complex polymers of sugar acid derivatives include pectin and closelyrelated substances. The cement-like substance found especially in the middlelamella which helps hold plant cells to one another is a water-insoluble pecticsubstance.

On mild hydrolysis it yields water-soluble pectin which can form gels orviscous colloidal suspensions with sugar and acid. Certain water-soluble pecticsubstances also react with metal ions, particularly calcium, to form water-insoluble salts such as calcium pectates. The various pectic substances mayinfluence texture of vegetables and fruits in several ways.

When vegetables or fruit are cooked, some of the water-insoluble pecticsubstance is hydrolysed into water-soluble pectin. This results in a degree ofcell separation in the tissues and contributes to tenderness. Since many fruitsand vegetables are somewhat acidic and contain sugars the soluble pectinalso tends to form colloidal suspensions which will thicken the juice or pulpof these products.

Fruit and vegetables also contain a natural enzyme which can furtherhydrolyse pectin to the point where the pectin loses much of its gel formingproperty. This enzyme is known as pectin methyl esterase. Materials such astomato juice or tomato paste will contain both pectin and pectin methylesterase.

If freshly prepared tomato juice or paste is allowed to stand the originalviscosity gradually decreases due to the action of pectin methyl esterase onpectin gel.

This can be prevented if the tomato products are quickly heated to atemperature of about 82°C (180 F°) to deactivate the pectin methyl esteraseliberated from broken cells before it has a chance to hydrolyse the pectin. Sucha treatment is commonly practiced in the manufacture of tomato juiceproducts. This is known as the “hot-break process” and yields products ofhigh viscosity.

In contrast, where low viscosity products are desired no heat is used andenzyme activity is allowed to proceed. This is “cold-break” process. Aftersufficient decrease in viscosity is achieved the product can be heat treated, as


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in canning, to preserve it for long term storage.It is often also desirable to firm the texture of fruit and vegetables,

especially when products are normally softened by processing. In this caseadvantage is taken of the reaction between soluble pectic substances andcalcium ions which form calcium pectates. These calcium pectates are waterinsoluble and when they are produced within the tissues of fruit andvegetables they increase structural rigidity. Thus, it is common commercialpractice to add low levels of calcium salts to tomatoes, apples, and othervegetables and fruits prior to canning or freezing.

Vitamins

Vitamins are defined as organic materials which must be supplied to thehuman body in small amounts apart from the essential amino-acids or fattyacids.

Vitamins function as enzyme systems which facilitate the metabolism ofproteins, carbohydrates and fats but there is growing evidence that their rolesin maintaining health may extend yet further.

The vitamins are conveniently divided into two major groups, those thatare fat-soluble and those that are water-soluble. Fat-soluble vitamins are A,D, E and K. Their absorption by the body depends upon the normal absorptionof fat from the diet. Water-soluble vitamins include vitamin C and severalmembers of the vitamin B complex.

Vitamin A or Retinol

This vitamin is found as such only in animal materials - meat, milk, eggsand the like. Plants contain no vitamin A but contain its precursor, beta-carotene. Man needs either vitamin A or beta-carotene which he can easilyconvert to vitamin A. Beta-carotene is found in the orange and yellowvegetables as well as the green leafy vegetables, mainly carrots, squash, sweetpotatoes, spinach and kale.

A deficiency of vitamin A leads to night blindness, failure of normal boneand tooth development in the young and diseases of epithelial cells andmembrane of the nose, throat and eyes which decrease the body’s resistanceto infection.

Vitamin C

Vitamin C is the anti-scurvy vitamin. Lack of it causes fragile capillarywalls, easy bleeding of the gums, loosening of teeth and bone joint diseases.It is necessary for the normal formation of the protein collagen, which is animportant constituent of skin and connective tissue. Like vitamin E, vitaminC favours the absorption of iron.

Vitamin C, also known as ascorbic acid, is easily destroyed by oxidationespecially at high temperatures and is the vitamin most easily lost during


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processing, storage and cooking.Excellent sources of vitamin C are citrus fruits, tomatoes, cabbage and

green peppers. Potatoes also are a fair source (although the content of vitaminC is relatively low) because we consume large quantities of potatoes.

Sources of Colour and Colour Changes

In addition to a great range of textures, much of the interest that fruitsand vegetables add to our diets is due to their delightful and variable colours.The pigments and colour precursors of fruit and vegetables occur for the mostpart in the cellular plastic inclusions such as the chloroplasts and otherchromoplasts, and to a lesser extent dissolved in fat droplets or water withinthe cell protoplast and vacuoles.

These pigments are classified into four major groups which include thechlorophylls, carotenoids, anthocyanins, and anthoanthins. Pigmentsbelonging to the latter two groups also are referred to as flavonoids, andinclude the tannins.

The Chlorophylls

The chlorophylls are contained mainly within the chloroplasts and havea primary role in the photosynthetic production of carbohydrates from carbondioxide and water. The bright green colour of leaves and other parts of plantsis largely due to the oilsoluble chlorophylls, which in nature are bound toprotein molecules in highly organised complexes.

When the plant cells are killed by ageing, processing, or cooking, theprotein of these complexes is denatured and the chlorophyll may be released.Such chlorophyll is highly unstable and rapidly changes in colour to olivegreen and brown. This colour change is believed to be due to the conversionof chlorophyll to the compound pheophytin.

Conversion to pheophytin is favoured by acid pH but does not occurreadily under alkaline conditions. For this reason peas, beans, spinach, andother green vegetables which tend to lose their bright green colours on heatingcan be largely protected against such colour changes by the addition of sodiumbicarbonate or other alkali to the cooking or canning water.

However, this practice is not looked upon favourably nor usedcommercially because alkaline pH also has a softening effect on cellulose andvegetable texture and also destroys vitamin C and thiamin at cookingtemperatures.

The Carotenoids

Pigments belonging to this group are fat-soluble and range in colour fromyellow through orange to red. They often occur along with the chlorophyllsin the chloroplasts, but also are present in other chromoplasts and may occurfree in fat droplets. Important carotenoids include the orange carotenes of


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carrot, maize, apricot, peach, citrus fruits, and squash; the red lycopene oftomato, watermelon, and apricot; the yellow-orange xanthophyll of maize,peach, paprika and squash; and the yellow-orange crocetin of the spice saffron.These and other carotenoids seldom occur singly within plant cells. A majorimportance of some of the carotenoids is their relationship to vitamin A. Amolecule of orange beta-carotene is converted into two molecules of colourlessvitamin A in the animal body. Other carotenoids like alpha-carotene, gamma-carotene, and cryptoxanthin also are precursors of vitamin A, but because ofminor differences in chemical structure one molecule of each of these yieldsonly one molecule of vitamin A.

In food processing the carotenoids are fairly resistant to heat, changes inpH, and water leaching since they are fat-soluble. However, they are verysensitive to oxidation, which results in both colour loss and destruction ofvitamin A activity.

The Flavonoids

Pigments and colour precursors belonging to this class are water-solubleand commonly are present in the juices of fruit and vegetables. The flavonoidsinclude the purple, blue, and red anthocyanins of grapes, berries, plump,eggplant, and cherry; the yellow anthoxanthins of light coloured fruit andvegetables such as apple, onion, potato, and cauliflower, and the colourlesscatechins and leucoanthocyanins which are food tannins and are found inapples, grapes, tea, and other plant tissues. These colourless tannin compoundsare easily converted to brown pigments upon reaction with metal ions.

Properties of the anthocyanins include a shifting of colours with pH. Thusmany of the anthocyanins which are violet or blue in alkaline media becomered upon addition of acid. Cooking of beets with vinegar tends to shift thecolour from a purplish red to a brighter red, while alkaline water can influencethe colour of red fruits and vegetables toward violet and gray-blue.

The anthocyanins also tend toward the violet and blue hues upon reactionwith metal ions, which is one reason for lacquering the inside of metal canswhen the true colour of anthocyanin-containing fruits and vegetables is to bepreserved.

The water-soluble property of anthocyanins also results in easy leachingof these pigments from cut fruit and vegetables during processing andcooking. The yellow anthoxanthins also are pH sensitive tending toward adeeper yellow in alkaline media. Thus potatoes or apples become somewhatyellow when cooked in water with a pH of 8 or higher, which is common inmany areas. Acidification of the water to pH 6 or lower favours a whiter colour.

The colourless tannin compounds upon reaction with metal ions form arange of dark coloured complexes which may be red, brown, green, grey, orblack. The various shades of these coloured complexes depend upon theparticular tannin, the specific metal ion, pH, concentration of the complex,


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and other factors not yet fully understood.Water-soluble tannins appear in the juices squeezed from grapes, apples,

and other fruits as well as the brews from extraction of tea and coffee. Thecolour and clarity of tea are influenced by the hardness and pH of the brewingwater. Alkaline waters that contain calcium and magnesium favour theformation of dark brown tannin complexes which precipitate when the tea iscooled.

If acid in the form of lemon juice is added to such tea its colour lightensand the precipitate tends to dissolve. Iron from equipment or from pitted tincans has caused a number of unexpected colours to develop in productscontaining tannins, such as coffee, cocoa and foods flavoured with these. Thetannins are also important because they have an astringency which influencesflavour and contributes body to such beverages as tea, wine, apple cider, etc.

ACTIVITIES OF LIVING SYSTEMS OF FRUIT AND VEGETABLES

Fruit and vegetables are in a live state after harvest. Continued respirationgives off carbon dioxide, moisture, and heat which influence storage,packaging, and refrigeration requirements. Continued transpiration adds tomoisture evolved and further influences packaging requirements. Furtheractivities of fruit and vegetables, before and after harvest, include changes incarbohydrates, pectins, organic acids, and the effects these have on variousquality attributes of the products.

As for changes in carbohydrates, few generalizations can be given withrespect to starches and sugars. In some plant products sugars quickly decreaseand starch increases in amount soon after harvest. This is the case for ripesweet corn which can suffer flavour and texture quality losses in a very fewhours after harvest.

Unripe fruit, in contrast, is frequently high in starch and low in sugars.Continued ripening after harvest generally results in a decrease in starch anda increase in sugars as in the case of apples and pears. However, this does notnecessarily mean that the starch is the source of the newly formed sugars.

Further, the courses of change in starch and sugars are markedlyinfluenced by postharvest storage temperatures. Thus potatoes stored belowabout 10 C° (50 F°) continue to build up high levels of sugars, while the samepotatoes stored above 10 C° do not.

This property is used to help the dehydration process in potato storage.Here potatoes should have a low reducing sugar content so as to minimiseMaillard browning reactions during drying and subsequent storage of thedried product. In this case potatoes are stored above 10°C prior to being furtherprocessed.

After harvest the pectin changes in fruit and vegetables are more


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predictable. Generally there is decrease in water-insoluble pectic substanceand a corresponding increase in watersoluble pectin. This contributes to thegradual softening of fruits and vegetables during storage and ripening. Furtherbreakdown of water-soluble pectin by pectin methyl esterase also occurs.

The organic acids of fruit generally decreases during storage and ripening.This occurs in apples and pears and is especially important in the case oforanges. Oranges have a long ripening period on the tree and time of pickingis largely determined by degree of acidity and sugar content which have majoreffects upon juice quality. It is important to note that the reduction of acidcontent on ripening influences more than just the tartness of fruit. Since manyof the plant pigments are sensitive to acid, fruit colour would be expected tochange. Additionally, the viscosity of pectin gel is affected by acid and sugarcontents, both of which change with ripening.

STABILIT Y OF NUT RIENT S

One of the principal responsibilities of the food scientist and foodtechnologist is to preserve food nutrients through all phases of foodacquisition, processing, storage, and preparation.

Table: Specific sensitivity and stability of nutrients

Nutrient Neutral Acid Alkaline Air or Light Heat Cooking

pH 7 < pH 7 > pH 7 Oxygen Losses,

Range

Vitamins

Vitamin A S U S U U U 0-40

Ascorbic U S U U U U 0-100

acid(C) Biotin S S S S S U 0-60

Carotenes S U S U U U 0-30

(pro A) 0-5

Choline S S S U S S 0-10

Cobalamin S S S U U S (B12) 0-40

Vitamin D S U U U U 0-10

Essential S S U U U S fatty acids Folic acid U U S U U U 0-100

Inositol S S S S S U 0-95

Vitamin K S U U S U S 0-5

Niacin (PP) S S S S S S 0-75

Pantbothenic S U U S S U 0-50

acid p-Amino S S S U S S 0-5


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Benzoic acid Vitamin B6 S S S S U U 0-40

Riboflavin S S U S U U 0-75

(B2) Tbiamin (B1) U S U U S U 0-80

Tocopherols S S S U U U 0-55

This shows the stability of vitamins, essential amino acids, and mineralsto acid, air, light, and heat, and gives an indication of possible cooking losses.Vitamin A is highly sensitive to acid, air, light and heat; vitamin C to alkalinity,air, light and heat; vitamin D to alkalinity, air, light and heat; thiamin toalkalinity, air, and heat in alkaline solutions; etc. Cooking losses of someessential nutrients may be in excess of 75%. In modern food processingoperations, however, losses are seldom in excess of 25%. The ultimate nutritivevalue of a food results from the sum total of losses incurred throughout itshistory - from farmer to consumer. Nutrient value begins with genetics of theplant and animal. The farmland fertilization programme affects tissuecomposition of plants, and animals consuming these plants. The weather anddegree of maturity at harvest affect tissue composition.

Storage conditions before processing affect vitamins and other nutrients.Washing, trimming, and heat treatments affect nutrient content. Canning,evaporating, drying, and freezing alter nutritional values, and the choices oftimes and temperatures in these operations frequently must be balancedbetween good bacterial destruction and minimum nutrient destruction.

PACKAGING AND SUBSEQUENT ST ORAGE AFFECT NUT RIENT S

One of the most important factors is the final preparation of the food inthe home and the restaurant - the steam table can destroy much of what hasbeen preserved through all prior manipulations.

Structural Features

The structural unit of the edible portion of most fruits and vegetables isthe parenchyma cell. While parenchyma cells of different fruit and vegetablesdiffer somewhat in gross size and appearance, all have essentially the samefundamental structure. Parenchyma cells of plants differ from animal cells inthat the actively metabolising protoplast portion of plant cells represents onlya small fraction, of the order of five per cent, of the total cell volume. Thisprotoplast is film-like and is pressed against the cell wall by the large water-filled central vacuole. The protoplast has inner and outer semi-permeablemembrane layers; the cytoplasm and its nucleus are held between them. Thecytoplasm contains various inclusions, among them starch granules andplastics such as the chloroplasts and other pigment-containing chromoplasts.

The cell wall, cellulose in nature, contributes rigidity to the parenchymacell and limits the outer protoplasmic membrane. It is also the structure against


41

which other parenchyma cells are cemented to form extensive three-dimensional tissue masses.

The layer between cell walls of adjacent parenchyma cells is referred toas the middle lamella, and is composed largely of pectic and polysaccharidecement-like materials. Air spaces also exist, especially at the angles formedwhere several cells come together. The relationships between these structuresand their chemical compositions are further outlined below. The parenchymacells will vary in size among plants but are quite large when compared tobacterial or yeast cells. The larger parenchyma cells may have volumes manythousand times greater than a typical bacterial cell. There are additional typesof cells other than parenchyma cells that make up the familiar structures offruit and vegetables. These include various types of conducting cells whichare tube-like and distribute water and salts throughout the plant.

Such cells produce fibrous structures toughened by the presence ofcellulose and the woodlike substance lignin. Cellulose, lignin, and pecticsubstances also occur in specialised supporting cells which increase inimportance as plants become older. An important structural feature of allplants, including fruit and vegetables is protective tissue. This can take manyforms but usually is made up of specialised parenchyma cells that are pressedcompactly together to form a skin, peel or rind.

FOOD PROCESSING TECHNOLOGIES

Food irradiation is one of the food processing technologies available tothe food industry to control organisms that cause food-borne diseases and toreduce food losses due to spoilage and deterioration. Food irradiationtechnology offers some advantages over conventional processes. Eachapplication should be evaluated on its own merit as to whether irradiationprovides a technical and economical solution that is better than traditionalprocessing methods.

Table: Possible Causes of Spoilage (Real or Aparent) in Canned Goods

Type of food: Acid and high acid foods (canned fruits)

Condition of can Action to be taken to identify cause

Insufficient vacuum or headspace Check vacuum and headspace in relation to

storage temperature and altitude

“Springer” or “flipper” Cool can to 15°C and check if still domed.

Check can for denting, if possible measure

headspace volume change brought about by

dents, by comparing can volume with volume

of a sound can

Hydrogen swell Check degree of detinning in can especially at


42

the liquid level. Look for scratches or

pinholes in lacquer or tin coating. Check if

can is still domed on cooling to 15°C.

“Hard” or “soft swell” Leaker spoilage. Check can for gross seam

faults, perforation due to corrosion or damage

to seams. Examine contents for signs of spoilage

and can interior for detinning at air/product

interface.

Applications

For products where irradiation is permitted, commercial applicationsdepend on a number of factors including the demand for the benefits provided,competitiveness with alternative processes and the willingness of consumersto buy irradiated food products. There are a number of applications of foodirradiation. For each application it is important to determine the optimumdosage range required to achieve the desired effect. Too high a dosage canproduce undesirable changes in texture, colour and taste of foods.

Shelf-life Extension

Irradiation can extend the shelf-life of foods in a number of ways. Byreducing the number of spoilage organisms (bacteria, mould, fungi),irradiation can lengthen the shelf life of fruits and vegetables.

Since ionising radiation interferes with cell division, it can be used as analternative to chemicals to inhibit sprouting and thereby extend the shelf lifeof potatoes, onions and garlic. Exposure of fruits and vegetables to ionisingradiation slows their rate of ripening. Strawberries, for example, have beenfound to be suitable for irradiation. Their shelf-life can be extended three-fold, from 5 to 15 days.

Disinfestation

Ionising radiation can also be used as an alternative to chemical fumigantsfor disinfestation of grains, spices, fruits and vegetables. Many countriesprohibit the importation of products suspected of being contaminated withlive insects to protect the importing country’s agricultural base. With thebanning of certain chemical fumigants, irradiation has the potential to facilitatethe international shipment of food products.

Global Developments

In 1980, an FAD/IAEA/WHO Expert Committee reviewed in detail allthe accumulated data on food irradiation from the past 40 years. The ExpertCommittee concluded that irradiation to an overall dose of 10 kGy (kilograys)presents no toxicological hazard and introduces no special nutritional or


43

microbiological problems, thus establishing the wholesomeness of irradiatedfoods up to an overall average absorbed dose of 10 kGy.

Data were insufficient to formulate conclusions on applications of foodirradiation above 10 kGy. Data on radiation chemistry, nutritional andmicrobiological aspects of food treated above 10 kGy is currently beingcompiled.

In 1983, the Codex Alimentarius Commission, an international group thatdevelops global food standards for the FAO and the WHO, incorporated the1980 Expert Committee’s conclusions regarding the wholesomeness ofirradiated foods into the Codex General Standard for Irradiated Foods. Thisproposed international standard was submitted to member countries to acceptor to modify according to individual country needs. Currently most countriesthat allow food irradiation approve its use on a case-by-case basis.

The Codex Alimentarius Commission has also adopted a RecommendedInternational Code of Practice for the Operation of Radiation Facilities for theTreatment of Foods. It is intended to serve as a guide for irradiator operatorsand government regulators.

International Trade

More than 30 countries have given clearances for the use of foodirradiation to process some 40 food items and approximately 30 facilitiesworld-wide treat food by irradiation processing. Approvals for additionalitems are being considered in many countries and many food irradiationfacilities are being planned. It was anticipated in 1988 that by 1990 there couldbe approximately 50 commercial/demonstration irradiators in 25 countries.

Table given below shows commercial applications of food irradiation tofruits and vegetables by country.Table: International Commercial Applications of Radiation for Fruit and Vegetables

Country Location (application Food Commodity

date)

Argentina Buenos Aires (1986) Spinach

Belgium Fleurus (1981) Dehydrated vegetables

Brazil Sao Paulo (1985) Dehydrated vegetables

Chile Santiago (1983) Dehydrated vegetables

onions, potatoes

China Shanghai (1985 Potatoes

Cuba Havana (1987) Potatoes, onions

German Dem. Rep Weideroda (1983) Onions, garlic

Spickendorf (1986) Onions

Japan Hokkaido (1973) Potatoes

Korea Seoul (1985 Garlic powder

Netherlands Ede (1978) Dehydrated vegetables


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South Africa Johannesburg (1981) Dehydrated vegetables

Tzaneen (1981) Fruits, onions, potatoes

Thailand Bangkok (1971) Onions

PRESERVATION OF VEGETABLES BY ACIDIFICATION

Food acidification is a means of preventing their deterioration in so faras a non-favourable medium for micro-organisms development is created.This acidification can be obtained by two ways: natural acidification andartificial acidification.

NAT URAL ACIDIFICAT ION

This is achieved by a predominant lactic fermentation which assures thepreservation based on acidoceno-anabiosys principle; preservation by lacticfermentation is called also biochemical preservation. Throughout recordedhistory food has been preserved by fermentation. In spite of the introductionof modern preservation methods, lactic acid fermented vegetables still enjoya great popularity, mainly because of their nutritional and gastronomicqualities.

The various preservation methods discussed thus far, based on theapplication of heat, removal of water, cold and other principles, all have thecommon objective of decreasing the number of living organisms in foods orat least holding them in check against further multiplication.

Fermentation processes for preservation purposes, in contrast, encouragethe multiplication of micro-organisms and their metabolic activities in foods.But the organisms that are encouraged are from a select group and theirmetabolic activities and end products are highly desirable. The extent of thisdesirability is emphasised by a partial list of fermented fruits and vegetableproducts from various parts of the world.

There are some characteristic features in the production of fermentedvegetables which will be pointed out below using cucumbers as an example.In the production of lactic acid fermented cucumbers, the raw material is putinto a brine without previous heating. Through the effect of salt and oxygendeficiency the cucumber tissues gradually die. At the same time, the semi-permeability of the cell membranes is lost, whereby soluble cell componentsdiffuse into the brine and serve as food substrate for the micro-organisms.

Under such specific conditions of the brine the lactic acid bacteria succeedin overcoming the accompanying micro-organisms and lactic acid as the mainmetabolic products is formed. Under favourable conditions (for examplemoderate salt in the brine, use of starter cultures) it takes at least 3 days untilthe critical pH value of 4.1 or less - desired for microbiological reasons - isreached. Beside the typical taste, for the consumer a crisp texture is the most


45

important quality criterion for fermented vegetables. Because there is noheating step before the fermentation, the indigenous plant enzymes in thefermenting materials are still present during the very first phase. After thedestruction of the cell membranes they easily get to their active sites and underfavourable conditions they can easily cause softening.

The environmental conditions act in a different manner on single enzymesor enzymes systems: some enzymes are strongly inhibited by salt, others areactivated, and in the acid pH-region many enzymes are irreversiblyinactivated. Beside indigenous enzymes also enzymes produced by micro-organisms can be responsible for the undesired soft products.

In technically advanced societies the major importance of fermented foodshas come to be variety they add to the diet. However, in many less developedareas of the world, fermentation and natural drying are the major foodpreservation methods and as such are vital to survival of a large proportionof the world’s current population.

Artificial acidification is carried out by adding acetic acid which is theonly organic acid harmless for human health and stable in specific workingconditions; in this case biological principles of the preservation areacidoanabiosys and, to a lesser extent, acidoabiosys.

Combined acidification is a preservation technology which involves as apreliminary processing step a weak lactic fermentation followed byacidification (vinegar addition). The two main classes of vegetables preservedby acidification are sauerkraut and pickles; the definitions of these productsadapted from US Code of Federal Register are as follows.

Bulk sauerkraut. Bulk or barrelled sauerkraut is the product ofcharacteristic acid flavour, obtained by the full fermentation, chiefly lactic, ofproperly prepared and shredded cabbage in the presence of 2-3% salt. Oncompletion of fermentation, it contains not more than 1.5% of acid, expressedas lactic acid.

Canned sauerkraut. Canned (or packaged) sauerkraut, is prepared fromclean, sound, well-matured heads of the cabbage plant (Brassica oleracea var.capitata L.) which have been properly trimmed and cut; to which salt is addedand which is cured by natural fermentation. The product may or may not bepacked with pickled peppers, pimientos, or tomatoes or contain otherflavouring ingredients to give the product specific flavour characteristics. Theproduct:

a. May be canned by processing sufficiently by heat to assurepreservation in hermetically sealed containers; or

b. May be packaged in sealed containers and preserved with orwithout the addition of benzoate of soda or any other ingredientpermissible under the provisions of Food and Drug Administration(FDA).

Pickles. “Pickles” means the product prepared entirely or predominantly


46

from cucumbers (Cucumis sativus L.). Clean, sound ingredients are usedwhich may or may not have been previously subjected to fermentation andcuring in a salt brine (solution of sodium chloride, NaCl).

The prepared pickles are packed in a vinegar solution to which may beadded salt and other vegetables, nutritive sweeteners, seasonings, flavourings,spices, and other ingredients permissible under FDA regulations. The productis packed in suitable containers and heat treated, or otherwise processed toassure preservation. Sauerkraut and pickle products can be preserved underthe effect of natural or added acidity, followed by pasteurization when thisacidification is not sufficient.

Sauerkraut is a very good source of vitamin C; the importance of thisproduct should be emphasised in developing countries as a simple technologywhich can be applied mainly for consumption of the finished products inremote, isolated areas during the cold season. It is also a excellent technologyto be learned to schools which have their own source of cabbage andcucumbers through school agricultural farms.

Sauerkraut and pickles are manufactured on an industrial scale insignificant quantities world-wide. However, the basic technology is simpleand could be applied at home, farm and community level after someexplanation and training. The natural acidification preservation could beconsidered similar to sun/solar drying in terms of training and development.TABLE: Some industrial fermentation processes in food industries

I. Lactic acid bacteria

— cucumbers dill pickles, sour pickles

— cabbage sauerkraut

— turnips sauerruben

— lettuce lettuce kraut

— mixed vegetables, turnips, radish, cabbage

— mixed Chinese vegetables, cabbage Kimchi

— vegetables and milk Tarhana

— vegetables and rice Sajur asin

II. Lactic acid bacteria with other micro-organisms

— with yeasts Nukamiso pickles

— with moulds tempeh, soy sauce

III. Acetic acid bacteria — wine, cider or any alcoholic and sugary or starchy products may be converted to vinegar

IV. Yeasts

— fruit wine, vermouth

The principle of this technology is to add sugar in a quantity that isnecessary to augment the osmotic pressure of the product’s liquid phase at alevel which will prevent microorganism development. From a practical pointof view, however, it is usual to partially remove water (by boiling) from the


47

product to be preserved, with the objective of obtaining a higher sugarconcentration. In concentrations of 60% in the finished products, the sugargenerally assures food preservation.

It is important to know the ratio between the total sugar quantity in thefinished product and the total sugar concentration in the liquid phase becausethis determines, in practice, the sugar preserving action. The percentcomposition of a product preserved with sugar, for example marmalade, canbe expressed as follows: [i + S + s + n + w] = 100;

i = insoluble substance;s = sugar from fruits;S = added sucrose;n = soluble “non sugar”;w = water.In this case, total sugar concentration, in the liquid phase, of the finished

product is:X = 100 (S + s)/100 - (n + i) [%]

Therefore, in the case of a standard marmalade with 55 % sugar added(calculated on the finished product basis), the real concentration in the liquidphase is for example:

X = 100 (55 + 8)/100 - (5 + 3) = 68.5%In the food preservation with sugar, the water activity cannot be reduced

below 0.845; this value is sufficient for bacteria and neosmophile yeastinhibition but does not prevent mould attack. For this reason, various meansare used to avoid mould development:

• Finished product pasteurization (jams, jellies, etc.);• Use of chemical preservatives in order to obtain the antiseptisation

of the product surface.It is very important from a practical point of view to avoid any product

contamination after boiling and to assure an hygienic operation of the wholetechnological process (this will contribute to the prevention of productmoulding or fermentation). Storage of the finished products in good conditionscan only be achieved by ensuring the above level of water activity.

HEAT PRESERVAT ION/HEAT PROCESSING

Various Degrees of Preservation

There are various degrees of preservation by heating; a few terms haveto be identified and understood.

a. Sterilisation. By sterilisation we mean complete destruction of micro-organisms. Because of the resistance of certain bacterial spores toheat, this frequently means a treatment of at least 121° C (250° F)of wet heat for 15 minutes or its equivalent. It also means that everyparticle of the food must receive this heat treatment. If a can of


48

food is to be sterilised, then immersing it into a 121° C pressurecooker or retort for the 15 minutes will not be sufficient because ofrelatively slow rate of heat transfer through the food in the can tothe most distant point.

b. “Commercially sterile”. Term describes the condition that exists inmost of canned or bottled products manufactured under GoodManufacturing Practices procedures and methods; these productsgenerally have a shelf-life of two years or more.

c. Pasteurized means a comparatively low order of heat treatment,generally at a temperature below the boiling point of water. Themore general objective of pasteurization is to extend product shelf-life from a microbial and enzymatic point of view; this is theobjective when fruit or vegetable juices and certain other foods arepasteurized.Pasteurization is frequently combined with another means ofpreservation - concentration, chemical, acidification, etc.

d. Blanching is a type of pasteurization usually applied to vegetablesmainly to inactivate natural food enzymes. Depending on itsseverity, blanching will also destroy some microorganisms.

Determining Heat Treatment/Thermal Processing Steps

Since heat sufficient to destroy micro-organisms and food enzymes alsousually has adverse effects on other properties of foods, in practice theminimum possible heat treatment should be used which can guaranteefreedom from pathogens and toxins and give the desired storage life; theseaims will determine the choice of heat treatment.

In order to safely preserve foods using heat treatment, the following mustbe known:

a. What time-temperature combination is required to inactivate themost heat resistant pathogens and spoilage organisms in oneparticular food?

b. What are the heat penetration characteristics in one particular food,including the can or container of choice if it is packaged?

Preservation processes must provide the heat treatment which will ensurethat the remotest particle of food in a batch or within a container will reach asufficient temperature, for a sufficient time, to inactivate both the mostresistant pathogen and the most resistant spoilage organisms if it is to achievesterility or “commercial sterility”, and to inactivate the most heat resistantpathogen if pasteurization for public health purposes is the goal.

Different foods will support growth of different pathogens and differentspoilage organisms so the target will vary depending upon the food to beheated.

Food acidity/pH value has a tremendous impact on the target in heat


49

preservation/processing. Table given below lists various types of fruit andvegetables and their pH value, together with the heat processing requirements.Table: Heat processing requirements — dependence on product acidity

Acidity class pH value Food item Heat and processing

requirements

Low acid 6.0 Peas, carrots, beets, High temperature

potatoes, asparagus processing 116-121°C

(240-250°F)

5.0 Tomato soup Medium acid 4.5 Tomatoes, pears, Boiling water

apricots, peaches processing 100°C

(212°F)

Acid 3.7 Sauerkraut, apple, High acid 3.0 Pickles

Sequence of Operations Employed in Heat Preservation of Foods

(Fruit and Vegetables, etc.)

In a simplified manner, the main operations employed in heatpreservation can be described as follows:

Food preparation Preparation procedures will vary with the type of food. For

fruit, washing, sorting, grading, peeling, cutting to size,

pre-cooking and pulping operations may be employed.

Can/receptacle This may be carried out manually or by using sophisticated

filling machinery. The ratio of liquid to solid in the can

must be carefully controlled and the can must not be

overfilled. A headspace of 6-9 mm depth (6-8% of the

container volume) above the level of food in the can is

usual.

Vacuum production This can be achieved by filling the heated product into the

can, by heating the can and contents after filling, by

evacuating the headspace gas in a vacuum chamber, or

by injecting superheated steam into the headspace.

In each case the can end is seamed on immediately

afterwards.

Thermal processing The filled sealed can must be heated to a high temperature

for a sufficient length of time to ensure the destruction of

spoilage micro-organisms. This is usually carried out in an

autoclave or retort, in an environment of steam under

pressure.

Cooling The processed cans must be cooled in chlorinated water to

a temperature of 37°C. At this temperature the heat

remaining is sufficient to allow the water droplets on the


50

can to evaporate before labelling and packing.

Labelling and packing Labels are applied to the can body, and the cans are then

packed into cases.

In principle, all these operations can also be carried out at the farm/community level using the appropriate small scale equipment, preferably onlyglass jars (e.g. no metal cans).

Technological Principles of Pasteurization

Physical and chemical factors which influence pasteurization process arethe following:

a. Temperature and time;b. Acidity of the products;c. Air remaining in containers.Pasteurization processes. In pasteurising certain acid juices for example,

there are two categories of processes:a. Low pasteurization where pasteurization time is in the order of

minutes and related to the temperature used; two typicaltemperature/time combinations are as following:63° C to 65° C over 30 minutesor75° C over 8 to 10 minutes.Pasteurization temperature and time will vary according to:• Nature of product; initial degree of contamination;• Pasteurized product storage conditions and shelf life required.

In this first category of pasteurization processes it is possibleto define three phases;

• Heating to a fixed temperature;• Maintaining this temperature over the established time period

(= pasteurization time);• Cooling the pasteurized products: natural (slow) or forced

cooling.b. Rapid, high or flash pasteurization is characterized by a

pasteurization time in the order of seconds and temperatures ofabout 85° to 90° C or more, depending on holding time. Typicaltemperature/time combinations are as follows:88° C (190° F) for 1 minute;100° C for 12 seconds;121°C for 2 seconds.

While bacterial destruction is very nearly equivalent in low and in highpasteurization processes, the 121° C/2 seconds treatment give the best qualityproducts in respect of flavour and vitamin retention. Such short holding times,however, require special equipment which is more difficult to design and


51

generally is more expensive than the 63-65 ° C/30 minutes type of processingequipment.

In flash pasteurization the product is heated up rapidly to pasteurizationtemperature, maintained at this temperature for the required time, thenrapidly cooled down to the temperature for filling, which will be performedin aseptic conditions in sterile receptacles. Taking into account the short timeand rapid performance of this operation, flash pasteurization can only beachieved in continuous process, using heat exchangers.

Industrial applications of pasteurization process are mainly used as ameans of preservation for fruits and vegetable juices and specially for tomatojuice.

Thermopenetration

The thermopenetration problem is extremely important, especially in thecase of the pasteurization of products packed in glass containers because it isthe determining factor for the success of the whole operation.

During pasteurization it is necessary that a sufficient heat quantity istransferred through the receptacle walls; this is in order that the producttemperature rises sufficiently to be lethal to micro-organisms throughout theproduct mass. The most suitable and practical method to speed upthermopenetration is the movement of receptacles during the pasteurizationprocess.

Rapid rotation of receptacles around their axis is an efficient means toaccelerate heat transfer, because this has the effect, among others of rapidlymixing the contents. The critical speed of for this movement is generally about70 rotations per minute (RPM). This enables a more uniform heating ofproducts, reducing heating time and organoleptic degradation.

Heating may precede or follow packaging. These principles of differenttemperature time combinations very largely determine the design parametresfor heat preservation equipment and commercial practices.

The food processor will employ no less than that heat treatment whichgives the necessary degree of micro-organism destruction. This is furtherensured by periodic inspection by local sanitary authorities or by the importingcountries sanitary services. However, the food processor also will want touse the mildest effective heat treatment to ensure highest food quality.

It is convenient to separate heat preservation practices into two broadcategories: one involves heating of foods in their final containers, the otheremploys heat prior to packaging. The latter category includes methods thatare inherently less damaging to food quality, where the food can be readilysubdivided (such as liquids) for rapid heat exchange. However, these methodsthen require packaging under aseptic or nearly aseptic conditions to preventor at least minimise recontamination.

On the other hand, heating within the package frequently is less costly


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and produces quite acceptable quality with the majority of foods and most ofour present canned food supply is heated in the package. In practice, therefore,most of the canned food produced locally in developing countries should beheated within the package.

RECENT T RENDS IN FRUIT AND VEGETABLE PROCESSING

New Products

The number and variety of fruit and vegetable products available to theconsumer has increased substantially in recent years. The fruit and vegetableindustry has undoubtedly benefited from the increased recognition andemphasis on the importance of these products in a healthy diet.

Traditional processing and preservation technologies such as heating,freezing and drying together with the more recent commercial introductionof chilling continue to provide the consumer with increased choice. This hasbeen achieved by new heating (e.g. UHT, microwave, ohmic) and freezing(e.g. cryogenic) techniques combined with new packaging materials andtechnologies (e.g. aseptic, modified atmosphere packaging). The overall trendin new fruit and vegetable products is “added value”, thus providingincreased convenience to the consumer by having much greater variety ofready prepared fruit and vegetable products. These may comprise completemeals or individual components. The suitability of products and packagesfor microwave re-heating has been an important factor with respect to addedconvenience.

Fruit and vegetable product trendsHeat processed products1. Canned fruits and vegetables

— Combination of vegetables in sauces and vegetable recipedishes. Exotic fruits

2. Glass packed fruits and vegetables— “Condiverde”/”antipasti” products based on vegetables in oil.— High quality fruit packs

3. Retortable plastics— Basic vegetables or vegetable meals— Fruit in jelly

4. Aseptic cartons— Ready made jelly

5. Rosti meals— Potato based products in retort pouches

6. Fruit juices— New combinations of juices and freshly squeezed products

7. Crisps— Thick and crunch skin-on crisps. Kettle or pan fried chips

Lower fat crisps


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Table: Numbers of New Fruit and Vegetable Products

1990 1991 1992 Jan-June

Frozen vegetable products 66 95 21

Chilled vegetable products 76 81 78

Heat processed vegetables 51 60 38

Heat processed fruits 13 14 5

Fruit juices and drinks 73 83 46

Potato crisps 32 33 16

New product development in the fruit and vegetable sector is mostimportant in meeting the continued challenge of providing the consumer withchoice and high quality products.

A Fresh Look at Dried Fruit

New fruit varieties and advance in drying technologies are putting a freshtwist on dried fruit applications. Fruits that have been introduced to the dryingprocess include cranberries, blueberries, cherries, apples, raspberries andstrawberries - not to mention the traditional mainstays of raisins, dates,apricots, peaches, prunes and figs.

Perceived as a “value-added” ingredient, dried fruit adds flavour, colour,texture and diversity with little alteration to an existing formula. Thegrowing interest in ethnic cuisines in U.S.A. and the change to a more healthyway of eating, has also moved dried fruit considerably closer to themainstream.

Found primarily in the baking industry, dried fruit is coming into its ownin various food products, including entrees, side dishes and condiments.Compotes, chutneys, rice and grain dishes, stuffings, sauces, breads, muffins,cookies, deserts, cereals and snacks are all food categories encompassing driedfruit.

Since some dried fruit is sugar infused (osmotic drying), food processorscan decrease the amount of sugar in formula - this is especially the case inbaked products.

Processors are making adjustments in moisture content of the dried fruitso that a varied range is available for different applications. An added bonusis dried fruits’ shelf stability (a shelf life of at least 12 months). Dried fruit ismore widely available in different forms, including whole dried, cut, dicedand powders.

Citric Acid and its Use in Fruit and Vegetable Processing

Citric acid may be considered as “Nature’s acidulant”. It is found in thetissues of almost all plants and animals, as well as many yeasts and moulds.Commercially citric acid is manufactured under controlled fermentation


54

conditions that produce citric acid as a metabolic intermediate from naturally-occurring yeasts, moulds and nutrients. The recovery process of citric acid isthrough crystallization from aqueous solutions.

Citric acid is widely used in carbonated and still beverages, to impart afresh-fruit “tanginess”. Citric acid provides uniform acidity, and its light fruitycharacter blends well and enhances fruit juices, resulting in improvedpalatability.

The amount of citric acid used depends on the particular desired flavour(e.g., High-acid: lemonade; Medium-acid: orange, punch, cherry; Low-acid:strawberry, black cherry, grape).

Sodium citrate is often added to beverages to mellow the tart taste ofhigh acid concentrations. It provides a cool, distinctive smooth taste and masksany bitter aftertaste of artificial sweeteners. In addition, it serves as a bufferto stabilise the pH at the desired level. The high water solubility of citric acid(181 g/100 ml) makes it an ideal additive for fountain fruit syrups andbeverages concentrates as a flavour enhancer and microbial growth inhibitor(preferably at pH < 4.6).

In processed fruits and vegetables, citric acid performs the followingfunctions:

a. It reduces heat-processing requirements by lowering pH: inhibitionof microbial growth is a function of pH and heat treatment. Higherheat exposure and lower pH result in greater inhibition. Thus theuse of citric acid to bring pH below 4.6 can reduce the heatingrequirements. In canned vegetables, citric acid usage is greatest intomatoes, onions and pimentos. For tomato packs, the NationalCanners Association recommends a pH of 4.1 to 4.3. In general, 0.1% citric acid will reduce the pH of canned tomatoes by 0.2 pHunits.

b. Optimise flavour: citric acid is added to canned fruits to providefor adequate tartness. Recommended usage level is generally lessthen 0.15%.

c. Supplement antioxidant potential: citric acid is used in conjunctionwith antioxidants such as ascorbic and erythorbic acids, to inhibitcolour and flavour deterioration caused by metal-catalysedenzymatic oxidation. Recommended usage levels are generally 0.1%to 0.3% with the antioxidant at 100 to 200 ppm.

d. Inactivate undesirable enzymes: oxidative browning in most fruitsand vegetables is catalysed by the naturally present polyphenoloxidase. The enzymatic activity is strongly dependent on pH.Addition of citric acid to reduce pH below 3 will resultin inactivation of this enzyme and prevention of browningreactions.


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Cherry and Apricot Oils are Safe for Food Use

The oils obtained by cold pressing the kernels of the cherry (Prunuscerasus) and the apricot (Prunus armeniaca) have been declared acceptablefor food use by the UK Ministry of Agriculture, Fisheries & Food’s AdvisoryCommittee on Novel Foods and Processes (ACNFP) by June 1993.

In its assessments of the safety in use of the cherry and apricot kerneloils, the ACNFP consider specifications that included data on fatty acidcomposition, the presence of natural antioxidants and the content of cyanide,mycotoxins and heavy metals.

The Committee says that it gave particular consideration to the possiblepresence in the oils of the cyanogenic glucoside amygdalin, from whichcyanide is released by enzymic action when the kernels of cherry and apricotare crushed. Amygdalin was found to be absent from the cherry and apricotkernel oils.

The ACNFP is satisfied that there are no food safety reasons why the useof cherry and apricot kernel should not be acceptable provided there iscompliance with the specifications shown in Table given below.

Table: Specification of Purity for Cherry and Apricot Kernel Oils

as Determined by UK ACNFP

Cherry Apricot

Contaminants limits:

Heavy metals (total) 0.5 mg/kg 0.5 mg/kg

Aflatoxins (total) 4.0 g/kg 4.0 g/kg

Cyanide 0.15 mg/kg 0.15 mg/kg

Pesticide residues 0.01 mg/kg 0.01 mg/kg

Tocopherols:

Alpha/delta/gamma (mg/kg) 356-886 569-899

The oils are obtained by the mechanical mincing and cold pressing ofkernels extracted from cleaned cherry or apricot stones. After filtering, theoils are stored and are to be sold in a raw, unrefined state. The cherry andapricot kernel oils are high unsaturated and are expected to be used asspeciality oils for salad dressings, baking and shallow frying applications.

The Use of Fruit Juices in Confectionery Products

During the last decade, the concept of fruit juices has gained immenselyon consumer popularity. The majority of new non-alcoholic and alcoholic fruitdrink products were a combination of syrups, fruit juices and flavours.

The confectionery industry followed suit and new products incorporatedfruit juices as part of their confectionery formulations and processes. Fruitjuice concentrates of high solids are often used instead of normal or single-fold juices.


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Juice concentrates are made of pure fruit juices. The process starts withpressing fruits and obtaining pure fruit juice; this is stabilised by heat treatmentwhich inactivates enzymes and micro-organisms. The next processing step isconcentration under vacuum up to 40-65° Brix or 4-7 fold. The concentratesare then blended for standardisation and stored.

These fruit juice concentrates are often further stabilised by the additionof sodium benzoate and potassium sorbate and are usually stored away fromlight and are refrigerated or frozen.

Depectinised fruit juices are also used to prevent foaming in confectioneryprocesses and are essential for use in clear beverage products. Fruit juiceconcentrates which are depectinised, and have added preservatives are calledstabilised, clarified, fruit juice concentrates.

Fruit juices are used in confectionery products in conjunction with naturaland artificial flavours which provides intense flavour impact and are cost-effective for a confectionery product.

The traditional concern in using fruit juice concentrates in confectioneryapplications has been the effect of the natural acids on the finished product,particularly the formation of invert sugar during processing.

This is a logical concern since concentrates contain differing amounts andtypes of acids. For example: apple, cherry, strawberry and other berries containprimarily malic acid. Grapes mainly contain tartaric acid. Cranberry is highin quinic acid. Citrus fruits and pineapple contain differing amounts of citricacid. The concentrates, when used, are normally buffered to a pH of 5-7 withsodium hydroxide.

In formulating products with fruit juice concentrates, the solids of theconcentrate are considered as mostly reducing sugars and a reduction in cornsyrup is made to compensate for equivalent amount of reducing sugar beingadded in the concentrate.

The exact replacement can be determined by measuring the D.E. of theconcentrate to be added. In formulations when small amounts of concentrateare used (less than 1%), no adjustment is made since the reducing sugarcontribution of the concentrate is not significant.

Fruit juice concentrates can also be used to provide a source of natural colour,in particular red colour. Grape, raspberry, cherry, strawberry and cranberryconcentrates in small amounts are very effective in colouring cream centres.

The inclusion of fruit juices in confectionery products is now left up tothe imagination of the manufacturer. These products must, of course, holdup to the standards of flavour integrity, and product excellence, during theshelf-life of these products.

THE QUALITY IN FRUITS AND VEGETABLES

Many publications speak generically of "consumer" as if a single type


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existed or as if his/her likes and preferences were perfectly defined. On thecontrary, consumption profiles are specific for each country or even regionand they vary with sex, age, and educational and socioeconomic level.However, there are universal behaviour patterns, therefore, for the purposeof this publication we will only refer to those characteristics and demandsthat are common worldwide and that may be useful to understand the averageconsumer.

In the first place, there is a world tendency towards a greater consumptionof fruits and vegetables due to a growing concern for a more balanced diet,with a lower proportion of carbohydrates, fats and oils and with a higherproportion of dietary fibre, vitamins, and minerals.

Another aspect that deserves attention is the tendency towardssimplification in the task of preparing daily meals. In the United States,until the 60s, the preparation of lunch or dinner required about 2 hoursand was planned in advance. Nowadays, meals are prepared in less thanone hour and the menu to be served at dinner begins to be defined after 4p.m.. The expanding incorporation of processed fruits and vegetables andother ready-made foods are partly responsible for this reduction in the timededicated to cooking. Probably, the most significant fact that encouragesthis tendency is woman's increasing incorporation in full-time work thatreduces her time to buy and to prepare foods but giving her more capacityto spend money.

Also influencing the consumption patterns is the increasing marketsegmentation through the expansion in shapes, colours, flavors, ways ofpreparation, and/or packaging in which a product is presented. Among others,tomatoes are an example of it, since today they can be purchased in at least 4different types: conventional or "beef tomato", "extended shelf life", "cherry",and processing types sold fresh, all of them in different sizes, packages andin some cases, colour. There is also an increasing supply of exotic or non-conventional fruits and vegetables, which together with the previous point,notably expands the purchase options. For example, in 1981, in a well-suppliedsupermarket of the USA, there were 133 options of different fruits andvegetables, but they increased to 282 in 1993 and to 340 in 1995. Withoutreaching these levels, the same tendency is observed in the different countriesof Latin America and the Caribbean.

Lastly, there is a growing demand for higher quality, external as well asinternal quality. External aspects (presentation, appearance, uniformity,ripeness, and freshness) are the main components in the decision to purchase,which is usually taken when the consumer sees the product exhibited at thesales point. This is particularly important in the self-service systems wherethe product must "self-sell" and if it is not chosen, represents a loss for theretailer. Internal quality (flavour, aroma, texture, nutritional value, andabsence of biotic and non-biotic contaminants) is linked to aspects not


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generally perceived externally, but are equally important to many consumers.To summarize the previous paragraphs we can say that within a general

tendency towards greater consumption and variety, the consumer demandsquality in terms of appearance, freshness, presentation as well as nutritionalvalue and safety.

DEFINIT ION OF QUALIT Y

The word "quality" comes from the Latin qualitas that means attribute,property or basic nature of an object. However, nowadays it can be definedas the "degree of excellence or superiority". Accepting this definition, we cansay that a product is of better quality when it is superior in one or severalattributes that are objectively or subjectively valued.

In terms of the service or satisfaction that it produces to consumers, wecould also define it as the "degree of fulfilment of a number of conditions thatdetermine its acceptance by the consumer". Here, a subjective aspect isintroduced, since different consumers will judge the same product accordingto their personal preferences. The destination or use can also determinedifferent criteria for judging quality within the same crop. For example, thetomato for fresh consumption is valued essentially by its uniformity, ripeness,and absence of defects, while colour, viscosity, and industrial yield as rawmaterial define the quality for ketchup tomatoes. It is common to useadditional words to define the quality to the specific use, such as "industrialquality", "nutritional quality", "export quality", "edible quality", etc.

Perception of Quality

Quality is a complex perception of many attributes that aresimultaneously evaluated by the consumer either objective or subjectively.The brain processes the information received by sight, smell, and touch andinstantly compares or associates it with past experiences or with textures,aromas, and flavours stored in its memory. For example, just by looking atthe colour, the consumer knows that a fruit is unripe and that it does nothave good flavour, texture or aroma. If colour is not enough to evaluateripeness, he/she uses the hands to judge firmness or other perceptiblecharacteristics. The aroma is a less used parameter except in those cases whereit is directly associated to ripeness like in melon or pineapple. This comparativeprocess does not take place when the consumer faces, for the first time, anexotic fruit whose characteristics are unknown.

The final evaluation is the perception of the flavour, aroma, and texturethat takes place when the product is consumed and when sensations perceivedat the moment of purchase are confirmed. If satisfaction is the result, loyaltyis generated. For example, if you discover that I prefer red apples to greenones, I will continue consuming red apples. It is possible to generate loyaltyto commercial brands, presentation forms, packaging, sales places, etc.


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Fruits and vegetables are consumed mainly for their nutritive value aswell as by the variety of shapes, colours, and flavors that make them attractivefor food preparation. When they are consumed raw or with very littlepreparation, the consumer's main concern is that they must be free of bioticor non-biotic contaminants that may affect health.


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3

Technology of Fruit Products

FRUIT QUALITY

Fruit quality goes back to tree stock, growing practices and weatherconditions. Closer to the shipper and processor, however, are the degrees ofmaturity and ripeness when picked and the method of picking or harvesting.

There is a distinction between maturity and ripeness of a fruit. Maturityis the condition when the fruit is ready to eat or if picked will become readyto eat after further ripening.

Ripeness is that optimum condition when colour, flavour and texture havedeveloped to their peak.

Some fruit is picked when it are mature but not yet ripe. This is especiallytrue of very soft fruit like cherries and peaches, which when fully ripe are sosoft as to be damaged by the act of picking itself. Further, since many typesof fruit continue to ripen off the tree, unless they were to be processed quickly,some would become overripe before they could be utilised if picked at peakripeness. From a technological point of view, fruit characterisation by speciesand varieties is performed on the basis of physical as well chemical properties:shape, size, texture, flavour, colour/pigmentation, dry matter content (solublesolids content), pectic substances, acidity, vitamins, etc.

These properties are directly correlated with fruit utilisation. The propertime to pick fruit depends upon several factors; these include variety, location,weather, ease of removal from the tree (which change with time), and purposeto which the fruit will be put.

For example, oranges change with respect to both sugar and acid as theyripen on the tree; sugar increases and acid decreases. The ratio of sugar toacid determines the taste and acceptability of the fruit and the juice.

For this reasons, in some countries there are laws that prohibit pickinguntil a certain sugar-acid ratio has been reached. In the case of much fruit tobe canned, on the other hand, fruit is picked before it is fully ripe for eatingsince canning will further soften the fruit.

QUALIT Y M EASUREM ENT S

Many quality measurements can be made before a fruit crop is picked inorder to determine if proper maturity or degree of ripeness has developed.Colour may be measured with instruments or by comparing the colour offruit on the tree with standard picture charts. Texture may be measured bycompression by hand or by simple type of plungers.

As fruit mature on the tree its concentration of juice solids, which aremostly sugars, changes. The concentration of soluble solids in the juice canbe estimated with a refractometre or a hydrometre. The refractometremeasures the ability of a solution to bend or refract a light beam which isproportional to the solution’s concentration. A hydrometre is a weightedspindle with a graduated neck which floats in the juice at a height related tothe juice density.

The acid content of fruit changes with maturity and affects flavour. Acidconcentration can be measured by a simple chemical titration on the fruit juice.But for many fruits the tartness and flavour are really affected by the ratio ofsugar to acid. Percentage of soluble solids, which are largely sugars, isgenerally expressed in degrees Brix, which relates specific gravity of a solutionto an equivalent concentration of pure sucrose.

In describing the taste of tartness of several fruits and fruit juices, theterm “sugar to acid ratio” or “Brix to acid ratio” are commonly used. Thehigher the Brix the greater the sugar concentration in the juice; the higher the“Brix to acid ratio” the sweeter and lees tart is the juice.

HARVEST ING AND PREPROCESSING

Harvesting

The above and other measurements, plus experience, indicate when fruitis ready for harvesting and subsequent processing. A large amount of theharvesting of most fruit crops is still done by hand; this labour may representabout half of the cost of growing the fruit. Therefore, mechanical harvestingis currently one of the most active fields of research for the agriculturalengineer, but also requires geneticists to breed fruit of nearly equal size, thatmatures uniformly and that is resistant to mechanical damage.

A correct manual harvesting includes some simple but essential rules:• The fruit should be picked by hand and placed carefully in the

harvesting basket; all future handling has to be performed carefullyin order to avoid any mechanical damage;

• The harvesting basket and the hands of the harvester should beclean;

• The fruit should be picked when it is ready to be able to beprocessed into a quality product depending on the treatment whichit will undergo.


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It is worth emphasising the fact that the proximity of the processingcentre to the source of supply for fresh raw materials presents majoradvantages; some are as follows:

• Possibility to pick at the best suitable moment;• Reduction of losses by handling/transportation;• Minimises raw material transport costs;• Possibility to use simpler/cheaper receptacles for raw material

transport.Once it has left the tree, the organoleptic properties, nutritional value,

safety and aesthetic appeal of the fruit deteriorates in varying degrees. Themajor causes of deterioration include the following:

a. Growth and activity of micro-organisms;b. Activities of the natural food enzymes;c. Insects, parasites and rodents;d. Temperature, both heat and cold;e. Moisture and dryness;f. Air and in particular oxygen;g. Light; andh. Time.

Reception — Quality and Quantity

Fruit reception at the processing centre is performed mainly for followingpurposes:

• Checking of sanitary and freshness status;• Control of varieties and fruit wholeness;• Evaluation maturity degree;• Collection of data about quantities received in connection to the

source of supply: outside growers/farmers, own farm.Variety control is needed in order to identify that the fruit belongs to an

accepted variety as not all are suitable for different technological processes.Fruit maturity degree is significant as industrial maturity is required for someprocessing/preservation methods while for others there is the need for anedible maturity when the fruit has full taste and flavour.

Special attention is given to size, appearance and uniformity of fruit tobe processed, mainly in the form of fruit preserved with sugar using whole/half fruits (“with fruit pieces”). Some laboratory control is also needed, evenif it not easy to precisely establish the technological qualities of fruit becauseof the absence of enough reliable rapid analytical methods able to showeventual deterioration.

The only reliable method for evaluating the quality is the combination ofdata obtained through organoleptic/taste controls and by simple analyticalchecks which are possible to perform in a small laboratory: percentage ofsoluble solids by refractometre, consistency/texture measured with simplepenetrometres, etc.


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Temporary Storage before Processing

This step has to be as short as possible in order to avoid flavour losses,texture modification, weight losses and other deterioration that can take placeover this period.

Some basic rules for this step are as follows:• Keep products in the shade, without any possible direct contact

with sunlight;• Avoid dust as much as possible;• Avoid excessive heat;• Avoid any possible contamination;• Store in a place protected from possible attack by rodents, insects,

etc.Cold storage is always highly preferred to ambient temperature. For this

reason a very good manufacturing practice is to use a cool room for eachprocessing centre; this is very useful for small and medium processing unitsas well.

Washing

Harvested fruit is washed to remove soil, micro-organisms and pesticideresidues. Fruit washing is a mandatory processing step; it would be wise toeliminate spoiled fruit before washing in order to avoid the pollution ofwashing tools and/or equipment and the contamination of fruit duringwashing.

Washing efficiency can me gauged by the total number of micro-organisms present on fruit surface before and after washing - best result arewhen there is a six fold reduction. The water from the final wash should befree from moulds and yeast; a small quantity of bacteria is acceptable.

Fruit washing can be carried out by immersion, by spray/showers or bycombination of these two processes which is generally the best solution: pre-washing and washing.

Some usual practices in fruit washing are:• Addition of detergents or 1.5% HCl solution in washing water to

remove traces of insect-fungicides;• Use of warm water (about 50°C) in the pre-washing phase;• Higher water pressure in spray/shower washers.

Washing must be done before the fruit is cut in order to avoid losinghigh nutritive value soluble substances (vitamins, minerals, sugars, etc.).

Sorting

Fruit sorting covers two main separate processing operations:a. Removal of damaged fruit and any foreign bodies (which might

have been left behind after washing);


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b. Qualitative sorting based on organoleptic criteria and maturitystage.

Mechanical sorting for size is usually not done at the preliminary stage.The most important initial sorting is for variety and maturity.

However, for some fruit and in special processing technologies it isadvisable to proceed to a manual dimensional sorting (grading).

Trimming and Peeling (Skin Removal)

This processing step aims at removing the parts of the fruit which areeither not edible or difficult to digest especially the skin.

Up to now the industrial peeling of fruit and vegetables was performedby three procedures:

a. Mechanically;b. By using water steam;c. Chemically; this method consists in treating fruit and vegetables

by dipping them in a caustic soda solution at a temperature of 90to 100° C; the concentration of this solution as well as the dippingor immersion time varying according to each specific case.

Cutting

This step is performed according to the specific requirements of the fruitprocessing technology.

Heat Blanching

Fruit is not usually heat blanched because of the damage from the heatand the associated sogginess and juice loss after thawing. Instead, chemicalsare commonly used without heat to inactivate the oxidative enzymes or toact as antioxidants and they are combined with other treatments.

Ascorbic/Citric Acid Dip

Ascorbic acid or vitamin C minimises fruit oxidation primarily by actingas an antioxidant and itself becoming oxidised in preference to catechol-tannincompounds. Ascorbic acid is frequently used by being dissolved in water,sugar syrup or in citric acid solutions.

It has been found that increased acidity also helps retard oxidative colourchanges and so ascorbic acid plus citric acid may be used together. Citric acidfurther reacts with (chelates) metal ions thus removing these catalysts ofoxidation from the system.

Sulphur Dioxide Treatment

Sulphur dioxide may function in several ways:• Sulphur dioxide is an enzyme poison against common oxidising

enzymes;


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• It also has antioxidant properties; i.e., it is an oxygen acceptor (asis ascorbic acid);

• Further SO2 minimises non enzymatic Maillard type browning byreacting with aldehyde groups of sugars so that they are no longerfree to combine with amino acids;

• Sulphur dioxide also interferes with microbial growth.In many fruit processing pre-treatments two factors must be considered:a. Sulphur dioxide must be given time to penetrate the fruit tissues;b. SO2 must not be used in excess because it has a characteristic

unpleasant taste and odour, and international food laws limit theSO2 content of fruit products, especially of those which areconsumer oriented (e.g. except semi-processed products oriented tofurther industrial utilisation).

Commonly a 0.25 % solution (except for semi-processed fruit productswhich are industry oriented and use a 6% solution) of SO2 or its SO2 equivalentin the form of solutions of sodium sulphite, sodium bisulphite or sodium/potassium metabisulphite are used.

Fruit slices are dipped in the solution for about two to three minutes andthen removed so as not to absorb too much SO2. Then the slices are allowedto stand for about one to two hours so that the SO2 may penetrate throughoutthe tissues before processing. Sulphur dioxide is also used in fruit juiceproduction to minimise oxidative changes where relatively low heat treatmentis employed so as not to damage delicate juice flavour.

Dry sulphuring is the technological step where fruit is exposed to fumesof SO2 from burning sulphur or from compressed gas cylinders; this treatmentcould be used in the preparation of fruits (and some vegetables) prior todrying/dehydration.

Sugar Syrup

Sugar syrup addition is one of the oldest methods of minimisingoxidation. It was used long before the causative reactions were understoodand remains today a common practice for this purpose.

Sugar syrup minimises oxidation by coating the fruit and therebypreventing contact with atmospheric oxygen. Sugar syrup also offers someprotection against loss of volatile fruit esters and it contributes sweet taste tootherwise tart fruits. It is common today to dissolve ascorbic acid and citricacid in the sugar syrup for added effect or to include sugar syrup after anSO2 treatment.

Fresh Fruit Storage

Some fruit species and specially apples and pears can be stored in freshstate during cold season in some countries’ climatic conditions. Fruit forfresh storage have to be autumn or winter varieties and be harvested before


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they are fully mature. This fruit also has to be sound and without anybruising; control and sorting by quality are mandatory operations.

Sorting has to be carried out according to size and weight and also byappearance; fruit which is not up to standard for storage will be used for semi-processed product manufacturing which will be submitted further toindustrial processing. Harvested fruit has to be transported as soon as possibleto storage areas. Leaving fruit in bulk in order to generate transpiration is abad practice as this reduces storage time and accelerates maturation processesduring storage. In order to store large quantities of fruit, silos have to be built.

Processing of Fruit Bars

The fruit bar processing method developed for FAO only involves a singlemajor operation, which it drying the fruit pulp after mixing it with suitableingredients. It can be used to produce mango, banana, guava or mixed fruitbars.

A dual-powered dryer, working by solar energy during the day and byelectric or steam power at night and on rainy days, with cross-flow movementof air and controlled temperature (from 55° C at the beginning of processingto a high of 70° C), is well suited for dehydration of the pulp to the desiredmoisture level of 15 to 20%.

Mango fruit bar — Fully ripe mangoes are selected and washed in waterat room temperature. The peeled fruit is cut into slices and passed through ahelicoidal pulper to extract the pulp. The required amount of sugar to adjustthe Brix (the unit measure for total solids in fruits) of the mixed pulp to 25degrees Brix is then added.

Two grams of citric acid per kilogram of pulp (or 20 ml of lime or lemonjuice) are added to inhibit possible growth of micro-organisms during drying.The mixture is then heated for two minutes at 80° C and partially cooled; theheat treatment serves to inactivate the enzymes and destroy the micro-organisms.

Potassium or sodium metabisulphite is added (two grams per kg ofprepared mixture), so that the concentration of SO2 is 1000 ppm. The mixtureis then transferred to stainless steel trays which have been previously smearedwith glycerine (40 ml/m²). Each tray must be loaded with 12.5 kg of mixtureper square metre. Drying could be carried out by a dual-powered dryer for atotal of 26 hours:

a. 10 hours by solar energy at about 55° C.b. 16 hours by electric or steam power at 70° C.At the end of the drying operation, when moisture content is between 15

and 20%, the pieces of suitable shape and size are wrapped in cellophanepaper, packed in cartons and stored at ambient air temperature. Pieces ofunsuitable shape and size are further cut into small pieces and used to prepare,along with peanuts and cashews, a variety of “cocktail mixtures”.


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Banana fruit bar. - Banana varieties which give smooth pulp withoutserum separation must be used for this purpose. Ripe, suitable fruit is selected.The hand-peeled fruits are soaked in 0.3 per cent citric acid solution for about10 minutes (lime or lemon juice can replace citric acid). The drained fruit arepulped to obtain smooth pulp.

The rest of the procedure is the same as in the case of the mango bar.

Guava Fruit Bar

A mixture of pink and yellow varieties is best suited for preparing thebar. The washed fruit is hand peeled and stem and blossom ends trimmed.The peeled fruit is cut into quarters which are passed through a helicoidalextractor to separate seeds and fibrous pieces (the holes in the stainless steelscreen should be between 0.8 and 1.10 mm).

To get the maximum yield of pulp, the material is passed through theextractor twice. After adjusting the refractometric solids to 25 degrees Brix,the fruit bar can be prepared by following the same procedure as for mangopulp.

Mixed Fruit Bar

Mango and banana pulp, as well as papaya and banana pulp, can bemixed in a calculated ratio for preparing mixed fruit bars. The rest of theprocedure is the same as in the case of pure mango pulp.

Packing and Storage

The dried pulp is removed from the dryer and cut into square pieces of 5x 5 cm at a thickness of about 0.3 cm. These pieces, arranged in three layersmake up blocks of about 0.9 cm thickness weighing between 25 and 28 grams.An unit pack consist of two such blocks and weights between 50 and 56 grams.

Each block is separately wrapped in cellophane and the unit pack is filledin a printed cellophane bag of size 15 x 8 cm. Two hundred unit packs arepacked in a master carton of size 34 x 22 x 14 cm, with a net weight of about10 kg. Shelf-life is about one year at room temperature.

Fruit Leathers

Fruit leathers are manufactured by drying/dehydration of fruit puréesinto leathery sheets. The leathers are eaten as confections or cooked as a sauce.They are made from a wide variety of fruits, the more common being apple,apricot, banana, cherry, blackcurrant, grape, peach, pear, pineapple, plum,raspberry, strawberry, kiwi fruit, mango and papaya.

A description of procedures for mango, banana, guava and mixed fruitbars is given in this document. Another product with good potential is cikuleather; ciku fruit is grown in Malaysia. A standard process is carried outusing ripe fruits which are washed, peeled, diced and the seeds removed. The


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fruits are blanched for 1 minute at 80° C and blended into puree in a foodprocessor. Ciku leather is prepared by mixing ciku puree with 10% sugar,10% pre-gelatinous rice flour, 150 ppm sorbic acid an 500 ppm sodiummetabisulphite (Na2H2SO4). The mixture is cooked on a water bath at 60° Cand then made into sheets 1.8 mm thick on trays spread with glycerol toreduce stickiness.

This is then further dried in a forced-air dehydrator at 45° C for 3.5 hr oruntil the surface no longer feels sticky when touched with the fingers. Thedried and cooled leathers are cut into 12 x 12 cm squares and wrapped inpolypropylene (PP) of 0.1 mm thickness.

Osmotic Dehydration in Fruit and Vegetable Processing

Osmotic dehydration is a useful technique for the concentration of fruitand vegetables, realised by placing the solid food, whole or in pieces, in sugarsor salts aqueous solutions of high osmotic pressure. It gives rise to at leasttwo major simultaneous counter-current flows: a significant water flow outof the food into the solution and a transfer of solute from the solution into thefood.

Process Variables

Main process variables are:a. Pre-treatments;b. Temperature;c. Nature and concentration of the dehydration solutions;d. Agitation;e. Additives.In the light of the published literature, some general rules can be noted:• Water loss and solid gain are mainly controlled by the raw material

characteristics and are certainly influenced by the possible pre-treatments;

• It is usually not worthwhile to use osmotic dehydration for morethan a 50% weight reduction because of the decrease in the osmosisrate over time. Water loss mainly occurs during the first 2 hr andthe maximum solid gain within 30 min;

• The rate of mass exchanges increases with temperature but above45 ° C enzymatic browning and flavour deterioration begin to takeplace. High temperatures, i.e. over 60° C, modify the tissuecharacteristics so favouring impregnation phenomena and thus thesolid gain;

• The best processing temperature depends on the food; massexchanges are favoured by using high concentration solutions;

• Phenomena which modify the tissue permeability, such as over-ripeness, pre-treatments with chemicals (SO2), blanching or freezing,


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favour the solid gain compared to water loss because impregnationphenomena are enhanced;

• The kind of sugars utilised as osmotic substances strongly affectsthe kinetics of water removal, the solid gain and the equilibriumwater content. Low molar mass saccharides (glucose, fructose,sorbitol, etc.) favour the sugar uptake;

• Addition of NaCl to osmotic solutions increases the driving forcefor drying.

Synergistic effects between sugar and salt have also been observed.

Applications

The effects of osmotic dehydration as a pre-treatment are mainly relatedto the improvement of some nutritional, organoleptic and functional propertiesof the product. As osmotic dehydration is effective at ambient temperature,heat damage to colour and flavour is minimised and the high concentrationof the sugar surrounding fruit and vegetable pieces prevents discolouration.

Furthermore, through the selective enrichment in soluble solids highquality fruit and vegetables are obtained with functional properties“compatible” with different food systems. These effects are obtained with areduced energy input over traditional drying process. The main energy-consuming step is the reconstitution of the diluted osmotic solution that couldbe obtained by concentration or by addition of sugar.

Drying

Air drying following osmotic dipping is commonly used in tropicalcountries for the production of so-called “semi-candied” dried fruits. The sugaruptake, owing to the protective action of the saccharides, limits or avoids theuse of SO2 and increases the stability of pigments during processing andsubsequent storage period.

The organoleptic qualities of the end product could also be improvedbecause some of the acids are removed from the fruit during the osmotic bath,so a blander and sweeter product than ordinary dried fruits is obtained. Owingto weight and volume reduction, loading of the dryer can be increased 2-3times. The combination of osmosis with solar drying has been put forward,mainly for tropical fruit. A 24 hour cycle has been suggested combiningosmodehydration, performed during the night, with solar drying during theday. Two-three-fold increase in the throughput of typical solar dryers isfeasible, while enhancing the nutritional and organoleptic quality of the fruits.

A two-step drying process, OSMOVAC, for producing low moisture fruitproducts was described. The osmotic step is performed with sucrose syrup65-75 Brix until the weight reduction reaches 30-50%. By osmotic dehydrationfollowed by vacuum drying puffy products with a crisp, honeycomb-liketexture can be obtained at a cost comparatively lower than freeze-drying.


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Commercial feasibility of the process on bananas has been studied, basedon the results of a semi-pilot scale operation; the process scheme. Osmoticallydried bananas retained more puffiness and a crisper texture than simplevacuum dried ones, and the flavour lasted longer at ambient temperature.The combination of osmotic dehydration with freeze-drying has beenproposed only at laboratory scale.

Appertisation

A combination of osmotic dehydration with appertisation has beenproposed to improve canned fruit preserves. The feasibility of a process, calledosmo-appertisation, to obtain high quality fruit in syrup, has been assessedon a pilot scale.

The key point of this technique is the pre-concentration of the fruit toabout 20-40 Brix, that causes, together with the enhancement of the naturalflavour, an increase of the resistance of the fruit to the following heat treatment,especially for colour and texture stability. The products obtained are stableup to 12 months at ambient temperature and show a higher organolepticquality than canned preserved alternatives.

Furthermore, because of their higher specific weight and diminishedvolume, the filling capacity of jars or pouches is increased.

Freezing

The frozen fruit and vegetable industry uses much energy in order tofreeze the large quantity of water present in fresh products. A reduction inmoisture content of the material reduces refrigeration load during freezing.

Other advantages of partially concentrating fruits and vegetables priorto freezing include savings in packaging and distribution costs and achievinghigher product quality because of the marked reduction of structural collapseand dripping during thawing.

The products obtained are termed “dehydro-frozen” and theconcentration step is generally carried out through conventional air drying,the additional cost of which has to be taken into account. Osmotic dehydrationcould be used instead of air drying to obtain an energy saving or a qualityimprovement especially for fruit and vegetable sensitive to air drying.

Extraction of Juices

An osmotic pre-step before juice extraction was reported to give highlyaromatic fruit or vegetable juice concentrates.

Further Developments

So far only applications on a pilot plant scale are reported in the literature.For further developments on a larger scale, theoretical and practical problemsshould be solved. The industrial application of the process faces engineering


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problems related to the movement of great volumes of concentrated sugarsolutions and to equipment for continuous operations. The use of highlyconcentrated sugar solutions creates two major problems. The syrup’s viscosityis so great that agitation is necessary in order to decrease the resistance to themass transfer on the solution side. The difference in density between thesolution (about 1.3 kg/litre) and fruit and vegetables (about 0.8 kg/litre), makesthe product float.

Another important aspect, so far not investigated, is the microbiologicalsafety of the process, which should be studied thoroughly before furtherindustrial development.

Apricot Processing

a. Fresh apricot puree:After washing, cutting and removal of stones, apricot halves aredipped in 2% solution of sodium or potassium metabisulphite for10 minutes. After draining, the resulting material is passed througha 0.045-in. screen pulper - finisher to produce a fresh apricot puree.The fresh apricot puree obtained in this way could be furtherprocessed in different semiprocessed (i.e. chemically or otherwisepreserved products) or finished fruit products (fruit leathers, fruitbars, jams, etc.).

b. Concentrated apricot pulp:Fresh apricot halves could also be steam blanched for 5 min., passedthrough a 0.045-in pulper - finisher and transformed in a puréewith about 14 Brix depending on the fruit quality. This purée maybe concentrated in steam jacketed kettles up to 20 Brix or in otheradequate equipment (e.g. a stirred vacuum evaporator) up to28°Brix.As for fresh apricot purée, the concentrate may be further processedin various semiprocessed or finished fruit products.

c. Dried apricot leather:• From fresh fruit purée by drum drying. The fresh apricot purée

at about 14 Brix could be dried to 12% moisture apricot sheets,using a double-drum dryer operating at 132 degrees C with adrum clearance of 0.008 in and speed of 45 sec per revolution.

• From fruit concentrate by drum drying. The concentrate couldalso be dried to 12% moisture fruit sheets by the same processas described above.

• From fresh fruit purée or from apricot concentrate by sun/solardrying or by dehydration.

a. Trays: For sun/solar drying or dehydration of fruit pulp, the traysmust have a solid base in order to retain the liquid contents. Theymay be made of metal, timber or plastic. Stainless steel or plastic


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trays are most suitable because they are unaffected by acid fruitpulp; they are, however, expensive.A metal tray could be 75 x 50 cm in size and with side 5 cm high.The trays must keep level during drying; if the tray is not level thepulp will run to the lowest point, giving a layer of irregular depthwhich will dry unevenly. Any tray which is not made of stainlesssteel or plastic must be covered inside with a sheet of heavy gaugeplastic film to protect the pulp from chemical or bacteriologicalcontamination.Standard sun/solar trays as described can be used by covering theminside with a sheet of plastic film to create a solid base.

b. Preparation before drying/dehydration: Fresh apricot purée can bedirectly used for next processing steps. Fruit concentrate needs tobe added to potassium metabisulphite to obtain a 0.3%concentration of SO2 in the material.

c. Drying/dehydration: The apricot/fruit purée or concentrate is pouredinto the trays to a depth of about 1.5 cm. When stainless steel orplastic trays are used they should be coated with a thin layer ofglycerine to prevent sticking.

The pulp is then sun/solar dried or tunnel/cabinet dehydrated; moisturecontent in the dried product should not exceed 14% and the SO2 content shouldnot be less than 1500 pp. The dried product is wrapped in cellophane toprevent sticking, then put inside polythene bags and stored at best in tightfitting tins and sealed to prevent moisture transfer.

From fresh fruit purée or from apricot concentrate, with sugar addition,and then processed by sun/solar drying or by dehydration. In some countriespreference is for finished products with added sugar; and this is alsointeresting from a point of view of energy consumption (concentration ispartially achieved by sugar dry matter) and of shelf life. The overall contentin SO2 could also be reduced as sugar is a preservation agent, the productwill be close to a fruit “paste”.

Reconstitution Test for Dried/Dehydrated Products

In reconstitution water is added to the product which is restored to acondition similar to that when it was fresh. This enables the food product tobe cooked as if the person was using fresh fruit or vegetable.

All vegetables are cooked but many of the dried fruits can be used foreating after they have been soaked in water. The following reconstitution testis used to find out the quality of the dried product.

Reconstitution test1. Weigh out a sample of 35 grams from the bulked and packed final

product of the previous day’s production.2. Put the sample into a small container (beaker) and add 275 ml of


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cold water (and 3.5 g salt).3. Cover the container (with a watch-glass) and bring the water to the

boil.4. Boil GENTLY for 30 minutes.5. Turn out the sample onto a white dish.6. At least two people should then examine the sample for palatability,

toughness, flavour and presence or absence of bad flavours. Thetesters should record their results independently.

7. The liquid left in the container should be examined for traces ofsand/soil and other foreign matter.

This test can be used also to examine dried products after they have beenstored for some time. Evaluation of rehydration ratio may be performedaccording to the following calculations.

Rehydration ratio. If weight of the dried sample is 10 g (Wd) and theweight of the sample after rehydration is 60 g (Wr), rehydration ratio is:

Wr 60 6= = ,6 to 1

Wd 10 1

Rehydration coefficient. The weight of rehydrated sample is 60 g (Wr);the weight of dried sample is 10 g (Wd) and its moisture is 5% (Wu); rawmaterial before drying had 87% water (A); rehydration coefficient is:

Wr

Wd- Wu× 100

100-A =

60× 100-87

10 10 0.05 =780

52.19.5

.

A simpler test for eating quality can be carried out without weighing andmeasuring. The material is placed in a cooking pot with water (and a littlesalt). The pot is then covered and boiled as described above.

Except for a few products which are eaten in the dry state, most driedfruit and all dried vegetables are prepared by soaking and cooking. Oftenthis preparation is carried out incorrectly and dried products get a badreputation. Good quality dried products, after cooking and if properly treatedshould be similar to cooked fresh produce. In order to get good results, thefollowing methods are recommended:

Quick Method

Cold water, ten times the weight of the dry product, is added to the driedproduct. The container is covered, brought to the boil and simmered GENTLYuntil the product is tender. The cooking time may be 15 to 45 minutes afterthe boiling point has been reached.

Slow Method

This gives better results than the quick method. Cold water is added to


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the dry food and is left to soak for 1 to 2 hours before cooking. The productis then cooked in the same water as that in which it was soaked. The actualcooking time will probably be shorter than that for the quick method.

Other points to remember are:• If too much water is added the cooked product will have little

flavour. However, if too little water is added the product may dryand burn. This can be avoided by adding small quantities of waterduring cooking;

• Always cook with a lid on the container;• Salt, if required, should be added when the cooking is almost

complete;• Partly used packages of dry products should be reclosed tightly or

kept in containers with good fitting lids.

Handling, Sorting, Packing and Storage of Dried and Dehydrated Fruits

and Vegetables

It is not easy to assess when drying has been completed. In absence ofinstrumentation, the characteristics of the various products after drying/dehydration can only be assessed by experience. Although this cannot beconveyed adequately on paper, some general indications can be given.

Fruit Products

When a handful of fruit is squeezed tightly together in the hand and thenreleased, the individual pieces should drop apart readily and no moisture beleft behind on the hand. It should not be possible to separate the skin byrubbing unpeeled fruit and the fruit centre should no longer reveal any moistarea. Banana should be leathery and not too tough to eat in their dry state.

Vegetable Products

Onions should be dried until they are crisp whereas tomatoes should beleathery. In general, the lower the moisture content, the better the keepingquality will be, but overdried products generally have an inferior quality. Alsothe loss in weight from excessive drying cannot be tolerated in a commercialoperation designed to run profitably.

It is, however, essential to dry up to an optimum/safe moisture level,related to the type of the product and his designed shelf life, and to avoidrunning the risk of the products becoming spoiled due to excess water content.When drying is completed, the material should be sorted either on trays oron a table in order to remove pieces of poor quality and colour and any foreignmatter.

Very fine material should be separated from the bulk of the material byusing a sieve (12 or 16 mesh per inch). Bad quality products which showpoor colour need to be removed from the bulk of finished product. After


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selection and grading, dried products should be packed immediately,preferably in polythene bags which must be folded and closed/tied tightly.However, plastic bags are easily damaged and therefore they must be packedinto cartons or jute sacks before they are transported.

Deterioration of Dried Fruit During Storage

Dried fruit must be considered as a relatively perishable commodity inthe same category as cereals, pulses and similar stored products. It is subjectto deterioration resulting from mould growth, insect and mite infestation andphysical and chemical changes.

Mould Growth

When the moisture content of dried fruit is allowed to exceed themaximum permissible level for safe storage then mould growth may occur.The moisture levels applicable to various types of fruit; and it can be seenthat the safe moisture levels for dried fruit are much higher than those forother similar commodities.

At the present time, suitable field moisture metres for use with dried fruitare not readily available, and moisture determinations can only besatisfactorily carried out where laboratory facilities are available.

Various species of drought resisting fungi may develop on dried fruitwhen the moisture content is just above the safe level, and a number ofosmophilic yeasts are quite commonly associated with spoilage in dried fruit.

Many of the yeasts bring about fermentation with the production of lacticacid or alcohol, and yeasts are frequently present in wart-like crystallinegrowths which occur in fruit which has become “sugared”. In very moist fruitmucoraceous fungi may predominate and are visible as white fluffy growthson and within the fruit.

Mite Infestation

Severe mite infestations are often associated with the growth ofosmophilic yeasts in fermenting dried fruit products. Many of these mitesare unable to complete their development in the absence of yeast. They havebeen reported as occurring on dried fruit, and particularly figs and prunes inMediterranean countries. Such infestations are difficult to eradicate and affectconsumer acceptance of the contaminated products.

Insect Infestation

Insect infestations may begin in the field before harvest, may continueduring bulk storage after drying, and unless measures are taken to preventit, may occur in the finished packaged product during storage prior todistribution and consumption.

Regular treatments of the stack of dried fruit with a suitable insecticide


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will be necessary as a routine to combat light insect infestations. Pyrethrinssynergised with piperonyl butoxide are commonly used as a surface spray oras an aerosol fog for this purpose. Heavy infestations will require that thefruit be fumigated.

TECHNOLOGY OF SEMI-PROCESSED FRUIT PRODUCTS

The semi-processed fruit products are manufactured in order to bedelivered to industry processing centres (in the fruit producing country itselfor in importing countries) where they will be further manufactured inconsumer oriented finished products: jams, jellies, syrups, fruits in syrup, etc.

In the practice of semi-processed fruit products and for the purpose ofthis document the following categories are defined:

a. Fruit “pulps”: semi-processed products, not refined, obtained bymechanical treatment (or, less often, by thermal treatment) of fruitfollowed by their preservation. Either whole fruit, halves or bigpieces are used which enables easy identification of the species.“Pulps” can be classified in boiled or non boiled (raw).

b. Fruit “purées-marks”: semi-processed products obtained by thermaland mechanical treatment or, very rare, raw and then refined,operations by which all nonedible parts (cores, peels, etc.) areremoved. “Purées-marks” are classified in boiled (the more usualcase) and non boiled (raw).

c. Semi-processed juices: products obtained by cold pressure or veryrare by other treatments (diffusion, extraction, etc.) followed by thepreservation.

Technical Processes for Preservation of Semi-processed Fruit Products

Preservation can be achieved by chemical means, by freezing or bypasteurization. The choice of preservation process for each individual case isa function of the semi-processed product type and the shelf life needed.

Chemical Preservation

In many countries, in practice, this is carried out with sulphur dioxide,sodium benzoate, formic acid and, on a small scale, with sorbic acid andsorbates.

Preservation with sulphur dioxide is a widespread process because of itsadvantages: universal antiseptic action and very economic application. Thedrawbacks of SO2 are: SO2 turn firms the texture of some fruit species(pomaces), desulphiting is not always complete and recolouring of red fruitsis not always complete after desulphitation.

Practical preservation dosage levels with SO2 for about 12 months is 0.18-


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0.20% SO2 (with respect to the product to be preserved).This level could be reduced to 0.09% SO2 for 3 months and to 0.12% SO2

for 6 months preservation. The preservation with sulphur dioxide is in usemainly for “pulps” and for “purées-marks”.

Chemical preservation can be performed from a practical point ofview by the utilisation of 6% SO2 water solutions or by direct introductionof sulphur dioxide gas in the product (for “purées-marks”). Thepreparation of 6% SO2 solutions is done by bubbling the gas from cylindersin cold water; from a 50 kg SO2 compressed gas cylinder results 830 l of 6%SO2 solution.

These SO2 solutions have to be stored in cool places, in closed receptaclesand with periodic concentration control/check by titration or by densitymeasurements approximate results.

Preservation with sodium benzoate has the following advantages: it doesnot firm up the texture and does not modify fruit colour. The disadvantagesare: it is not a universal antiseptic, its action needs an acid medium and theremoval is partial. Sodium benzoate is in use for “pulps” and for “purées-marks” but less for fruit juices.

Practical dosage level for 12 months preservation is 0.18-0.20 % sodiumbenzoate, depending on the product to be preserved. Sodium benzoate is usedas a solution in warm water; the dissolution water level has to be at maximum10% reported to semi-processed product weight.

Formic acid preservation is performed mainly for semi-processed fruitjuices at a dosage level of 0.2 % pure formic acid (100%). Formic acid is anantiseptic effective against yeasts, does not influence colour of products andis easily removed by boiling.

Formic acid could be diluted with water in order to insure a homogeneousdistribution in the product to be preserved; water has to be at maximum 5 %of the product weight. Because of a potential effect of pectic substancedegradation, formic acid is less in use for “pulps” and “purées-marks”preservation.

Sorbic acid used as potassium sorbate (easily water soluble) can be usedfor preservation of fruit semi-processed products at a dosage level of 0. 1%maximum. Advantages of sorbates are: they are completely harmless andwithout any influence on the organoleptic properties of semi-processed fruitproducts.

Preservation by Pasteurization

As fruit has a low pH, preservation of semiprocessed fruit products couldalso be performed by pasteurization (heat treatment step at maximumtemperature of 100°C), the length of this step varying with the size of thereceptacles. The advantages of this type of treatment are: hygienic process,which assure a long term preservation; the disadvantages are: need for air


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tight receptacles, and pectic substances could begin to deteriorate if the thermaltreatment is too long.

Thermal preservation of fruit semi-processed products could also be doneby a “selfpasteurization”: very hot semi-processed products are filled intoreceptacles (e.g. metal cans) which are sealed and then inverted in order tosterilise the air which goes through the hot fruit mass.

Preservation by Freezing

This is done on an industrial scale in some countries and can be donewith or without sugar addition. The advantages of this process are: absenceof added substances; very good preservation of quality of fruit constituents(pectic substances, vitamins, etc.) and good preservation of organolepticproperties (flavour, taste, colour). Freezing is done at about -20 to -30° C andstorage at -10 to -18° C.

Freezing is applied mainly to semi-processed fruit products aimed at veryhigh quality and high cost finished products. Technological flow-sheet forsemi-processed fruit “pulps”: chemical preservation.

Sorting is needed in order to remove sub-standard fruit (with moulds,with diseases, etc.) and all foreign bodies.

Washing is obligatory in order to remove all impurities which cannot beeliminated at the processing step in finished products.

Coring and Cutting, mainly for pomace fruits, has as main objective abetter utilisation of preservation “space” in receptacles and is not mandatory;this will be defined by customer/supplier agreements/standards. Thisoperation is preferably performed by mechanical means.

Preservation is carried out with the 6% SO2 solution which is added tothe prepared fruits (placed in bulk in receptacles) in the quantity needed toobtain the preservation dosage level. For a better/homogeneous preservativedistribution, the initial 6% SO2 solution could be diluted with water; however,the diluted solution (which will be filled in receptacles) has to be at a dosagelevel of less than 10% of the semi-processed product weight.

For some soft fruit, especially strawberries, preservation is done with amix of 6% SO2 solution and calcium bisulphite solution (containing also 6%SO2).

Preparation of calcium bisulphite solution is done by the introduction of30 kg of CaO in 1 m³ SO2 solution and mixing up to clarification. The resultingsolution is mixed with the initial 6% SO2 solution, generally in a 1:1 ratio, butthe ratio can be adapted to the fresh fruit texture. Firming of soft fruit textureby this treatment is based on the formation of calcium pectate with pecticsubstances from fruit tissues.

In the case of sodium benzoate, formic acid or potassium sorbate, thedosage levels to be used are as indicated above with the rule that it is notallowed to add more that 10% liquid in receptacles on the prepared fruits.


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Preservation by pasteurization or “self-pasteurization” will need asadditional steps: a) boiling with a minimum water addition (maximum 10%);b) filling of receptacles; c) hermetic closing followed by d) pasteurization or“self-pasteurization”.

Processing of Pineapple-papaya Jam

The fruit should be prepared as per previous instructions.For pineapples, the ends are removed and discarded; the cores and outer

parts of the fruits are also removed. The fruit cylinders obtained are pulpedthrough a special extractor (Fitzpatrick communiting machine) equipped witha 0.40-in screen sieve; the pulp thus obtained is used for making jam.

The papaya are prepared by hand-peeling the fruit; the fruit is then halvedand the seeds removed. It is then pulped in the communiting machine usinga 0.40-in screen sieve.

When ginger root is used as flavouring, it is peeled and macerated in aKenwood blender to a very fine consistency.

A typical formula for a pineapple-papaya jam (50:50 ratio) with gingerflavouring is given as follows:

Pineapple pulp 25.0Papaya pulp 25.0 poundsCane sugar 50.0Apple pectin (150 grade) 6.0 ouncesCitric acid 6.4Fresh ground ginger 7.5

Processing is carried out in the following way:The weighed fruit pulp is placed in a stainless steel steam-jacketed kettle

and heated to about 110°F under constant stirring.When the product reaches this temperature, the heat is turned off. The

pectin (mixed in about ten times its weight with some of the weighed sugar),is then mixed into the fruit pulp, stirring constantly in order to prevent thepectin from clotting.

When the pectin has dissolved, the remainder of the sugar is added anddissolved completely in the mixture. The heat is then turned on and the jammixture is stirred constantly until it starts boiling vigorously. During theremainder of the cooking, the product is stirred occasionally. Near the finishingpoint (approximately 221° F), the citric acid and the ginger (if it is used) arealso added.

Determination of the finishing point is done by removing samples atintervals, cooling, and reading the soluble solids by means of a refractometreequipped with a Brix scale. After the jam reaches the proper Total SolubleSolids content, the heat is turned off and the surface scum/foam is removed.

The jam then is quickly put into receptacles which have been cleaned


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and sterilised with boiling in water for 30 minutes. The filling operation isdone rapidly in order to prevent the temperature of the jam from falling below190° F.

After filling, sterilised lids (boiled for 30 minutes in water) are placed onthe receptacles and they are then sealed.

After this operation the receptacles are inverted for about 3 minutes toinsure that the lids are sterilised. The receptacles are then placed upright. Atthis stage it is not necessary to do any further processing, therefore thereceptacles are cooled in running cold water until they reach a temperatureslightly above room temperature. They are then dried in air and labelled.

Evaluation of Finished Products

During production at medium/large scale, it is recommended that qualitycontrols be performed during manufacturing. After ten weeks of storage atroom temperature it is recommended that an examination of finished productsbe performed. The receptacles are opened and contents carefully emptied onto enamel trays without disturbing the formation of the jam.

The empty cans (if metal cans were used) are then inspected for signs ofcorrosion. Factors other than flavour include colour, appearance, syrupseparation, firmness and spreading quality. For flavour, jam is tested on piecesof bread. Samples are taken for measurement of pH (with a glass electrodepH metre) and Total Soluble Solids (with a refractometre equipped with aBrix scale).

This evaluation enables to have a quality check during product shelf lifeand to obtain data needed for necessary improvements of future productions.

For pineapple-papaya jam, products made with 30% pineapple and 70%papaya with added ginger has the highest score for flavour. The use of plaintin cans causes corrosion problems which is not the case when acid resistantlacquer cans are used.

Gelified Sugar Fruit Preserves

Technology of Fruit Jellies

Jellies are gelified products obtained by boiling fruit juices with sugar,with or without the addition of pectin and food acids. Jellies are usuallymanufactured from juices obtained from a single fruit species only, obtainedby boiling in order to extract as much soluble pectin as possible.

Jellies have to be clear, shiny, transparent and with a colour specific tothe fruit from which they are obtained. Once the product is removed fromthe glass receptacles where it was packed, jellies must keep their shape andgelification and not flow, without being sticky or of a too hard consistency.

Technological flow-sheet for jellies manufacturing covers two categoriesof operations: those to obtain gelifying juices and those related to themanufacturing of jelly itself.


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a. Production of gelifying juices:Washing & Sorting are carried out in usual conditions.Cutting is applied eventually only to pomaces (apples, quinces) andare limited to cutting in halves or quarters.Boiling is performed with water addition with 50-100% water,needed for pectin extraction. The boiling time is 30-60 min., it shouldnot be longer so as to avoid pectin degradation; at the same timeboiling must not be too violent.Juice separation is carried out by a simple drain through metallicsieve or cloths; in these cases the yield is lower and the residue canbe used for marmalade production. In bigger productions it juiceseparation by hydraulic press is preferred, yield being in these casesgreater.Juice clarification is strictly necessary in order to obtain clear jellies.This step can be achieved by sedimentation during 24 hours or byfiltration.

b. Manufacturing of jellies:Basic Recipe Seting is done starting with equal parts in weight ofsugar and juice (for example 1000 g juice and 1000 g sugar). Asfinal jelly has to contain about 60% added sugar, weight of finishedproduct must be of about 1600 g, by evaporation of about 400 gwater.Boiling is carried out as following: juice is boiled up to removal ofabout half of the water that has to be evaporated, then the calculatedsugar quantity is added gradually; the remainder of the water isevaporated until a concentration in soluble substances(refractometric extract) of 65-67% is reached, in which isincorporated also the sugar from juice.During boiling it is necessary to remove foam/scum formed. Productacidity must be brought to about 1% (malic acid) corresponding topH > 3. Any acid addition is performed always at the end of boiling.For juices rich in pectin, gelification will occur without pectinaddition. If at the trial boiling test the gelification has not occurred,because of pectin absence, in this case 1-2% powder pectin will beadded by operating as indicated: pectin is mixed with 10-20 foldsugar quantity and is introduced directly in the partially evaporatedjuice and then boiling is conducted rapidly up to final point.Evaluation of final point is done not only by refractometry but alsoby gelifying test.A rapid test for evaluation of juice pectin content is possible bymixing a small sample of juice with an equal volume of 96% alcohol;the apparition of a compact gelatinous precipitate indicates asufficient pectin content for gelification.


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Boiling of jellies is performed in small batches (25-75 kg) in orderto avoid excessively long boiling time which brings about pectindegradation.Cooling is optional and is carried out up to 85 deg. C, in doublewall baths with water circulation.Filling is performed at a temperature not below 85 deg. C inreceptacles (glass jars, etc.), which must be maintained still about24 hours to allow cooling and product gelification.Receptacle closing is done after product gelification.Usual jelly types are: quinces, strawberries, cherries, wild berries,alone or in mixes with apples.

Grading of Marmalades

Three categories can be defined:• Fine marmalade, manufactured from one fruit;• Superior marmalade, obtained from a mix of fruit in which 30%

are “noble” species (cherries, strawberries, apricots, etc.) and 70%from other species;

• Marmalade from fruit mixes; apples, pears, plums, quinces,ungrafted apricots and wax cherries may be used, with the optionaladdition of “superior” fruit which was rejected at sorting but whichwas sound.

The content in total soluble substances (refractometric extract) ofmarmalades must be 64% minimum; the acidity must be between 0.5% and1.8% expressed as malic acid.

Basic Recipe Setting For a normal composition - marmalade withoutpectin addition the following is a basic recipe:

100 kg semi-processed fruit product(10% refractometric extract) …………… 10 kg soluble substances55 kg sugar ………………………………. 55 kg soluble substances155 kg 65 kg soluble substances55 kg water to be evaporated100 kg marmalade with 65% refractometric extract

This marmalade satisfies many standards and at same time has a goodshelf-life since it contains less than 35% water. Semi-processed fruit productsmust have a minimum 8% refractometric extract; in this case the recipe shoulduse 125 kg of raw material, with 80 kg water to be evaporate.

The use of semi-processed fruit products with a low refractometric extractpresents the following drawbacks:

a. Higher water quantity to be evaporated;b. Longer boiling times with negative impact of pectin degradation;c. Loss of flavour; andd. Lower equipment efficiency.


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Pectin addition in marmalade manufacture produces the followingadvantages:

a. Improvement of gelification;b. Economy in fruit;c. Shorter boiling time; this maintains taste and flavour and produces

higher equipment efficiency.Pectin addition makes it possible to obtain the “fine” type of marmalade

from “noble” fruits which do not contain enough pectin (cherries, peaches,apricots, etc.). In marmalades from fruit mixes, low pectin content can becompensated by addition of semi-processed fruit products which are rich inthis component (for example apples).

When pectin is to be added, the above recipe should be modified asfollows:

80 kg semi-processed fruit product(10% refractometric extract) …………… 8 kg soluble substances55 kg sugar ………………………………. 55 kg soluble substances10 kg pectic extract (10 % R.E.) ………. 1 kg soluble substances145 kg 64 kg soluble substances45 kg water to be evaporated100 kg marmalade with 64% refractometric extract

Pectin can be added as pectic extract with about 10% refractometric extract(R.E.) in the recommended proportion or in the form of a powder consideredwith 100% dry matter (e.g. 100% soluble substances) in a quantity of about1%.

In some countries it is usual to add 5-12% of corn syrup (calculated tofinished product weight) to replace the corresponding quantity of sugar (100parts corn syrup can replace 80 parts sugar). Corn syrup has to be liquefiedby heating before use. Corn syrup addition reduces the too sweet taste ofmarmalade, avoids sugar crystallisation and gives a special shine to finishedproducts.

Marmalade manufacturing follows the technological line and covers thefollowing steps:

“MARK” Preparation can be achieved from fresh fruits or starting fromchemical preserved semiprocessed fruit products: “marks” or “pulps”. In thelatter case, pulps will be processed in marks which then will be desulphitated.

Desulphitation is carried out by boiling at atmospheric pressure, undervacuum in specialised equipment or under pressure in special retorts built inacid-resistant material. In any case, the desulphitation must be carried outbefore sugar addition because sugar will bound to the sulphur dioxide. Thedesulphitation operation must be conducted so as to be, if possible, fullycompleted; the finished product must contain less than 0.005% free SO2.

The technological flow for marmalade production is the following: freshfruit after sorting on control belt (1) is washed in a washing machine (2) is


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brought to the continuous boiling equipment (3) then to the pulper (4); thesemi-finished mark is passed on to the storage tank (6). Pulps are boiled anddesulphited in continuous boiling equipment (3), then are brought to pulper(4) and to the storage tank (6).

Boiling aims at evaporating the required water quantity, to facilitate theformation of pectin-sugar-acid gel and to partially invert sugar (about 40%from total sugar). The boiling operation can be carried out in open kettles orin evaporators under vacuum.

In the latter case, the warm “mark” from storage tank (6) is aspirated ina concentrator (7) in a vacuum and submitted to a partial boiling up to removalof half of water quantity which needs to be evaporated; the calculated sugarquantity is then added by aspiration, keeping the boiling on.

After this the pectin extract or powder pectin which has previously beendissolved in warm water, is added; when the final concentration is reached,as indicated by refractometric control, the required quantity of acid is added.Sugar is added in proportion of 55% in finished product, pectic extract(10% refractometric extract) at a level of about 10-15% and the acid (citric,tartaric, lactic) in a quantity needed to obtain a finished product acidity ofabout 1%.

Boiling at atmospheric pressure affects not only the appearance but alsothe nutritional value of the products, mainly if these contain proteins, as somealbuminoids coagulate even at 60°C.

Food products for which flavour is an essential property as for examplefruit juices, etc., are also affected by the action of heat. Heat treatment has animpact on vitamin losses, mainly of vitamin C, in the presence of oxygen as isthe case at concentration in open vessels.

Sugars are generally less damaged by heat at temperatures below 100°C; as the boiling point is increasing above 100° C, a risk of partial sugarcaramelization exists. In the study of heat effects on products submitted toconcentration operation, it is necessary to take into account not only theevaporation surface temperature but also the distribution of the temperaturein the whole liquid mass.

The length of the heating period also has a major influence because inmany cases it is preferable to concentrate the liquid at a relatively hightemperature in a short time avoiding the drawbacks of lower temperaturesacting during a long time.

In order to maintain the food value and organoleptic properties, it isnecessary that concentration take place at a low temperature which can beachieved by concentration under partial vacuum, taking into account thatboiling point decreases when the residual pressure decreases, respectivelywith the increase of vacuum degree.

Advantage of concentration under partial vacuum are the following:• Lowering of boiling point;


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• The total time needed for concentration of food products under aresidual pressure of about 200 mm Hg is about half as comparedto the that of concentration by boiling at atmospheric pressure;

• By lowering the concentration temperature and time, organolepticproperties and of nutritional value are maintained better particularlyas far as the vitamins are concerned;

• When products are concentrated in a vacuum, it is possible torecover volatile aromatic substances by using adequate installations.

Technical procedures of concentration by vaporisation can be classifiedin:

a. Concentration at atmospheric pressure: continuous or discontinuous;b. Concentration under partial vacuum: discontinuous (in vacuum

equipment with simple or multiple effect) or continuous (in vacuuminstallations with continuous action or in thin film vaporisationinstallations).

Even if open kettle equipment is less expensive than evaporators in avacuum, it is necessary to take into account that boiling under vacuum hasthe following advantages:

a. Low boiling temperature (60-70° C), depending the degree of thevacuum; this give the fruit better taste and flavour-keeping qualities;

b. Easy feeding with raw and auxiliary materials;c. Shorter boiling time;d. Better working conditions (vapour elimination in condensed water

and not in open air).There are small size evaporators under vacuum which can be well suited

to the needs of medium size operations in developing countries.Cooling of marmalade to about 50-60°C can even be done in a vacuum

evaporator by closing the heating steam and maintaining vacuum degree or bydischarge in storage tanks (8).

Filling in receptacles (boxes, jars, glasses, etc.) is done preferably withfilling machines (9) followed by labelling(10). Small packages can be closedwarm or after complete cooling; big packages (boxes, etc.) must be closed onlyafter cooling, e.g. 24 hours after processing.

STORAGE of marmalade must be done in dry rooms (air relativehumidity at about 75%), well ventilated, medium cool places (temperature10-20 degrees C), disinfected and away from direct sunlight and heat. Thesemeasures are necessary because marmalade is a hydroscopic product and, bywater absorption, favourable conditions for mould development are created.

Technology of Special Fruit Jams

Special fruit jams are products similar to marmalades but in which fruitpartially keep their shape (whole, halves, etc.). Special fruit jams are obtainedby boiling fruit with sugar, with or without pectin addition, with acid addition


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followed by n concentration by evaporation.Special fruit jams present a pronounced gelification at their cooling and

can be considered as fruits included in a pectin-sugar-acid gel.High quality special fruit jams are obtained only from fresh fruit or

possibly frozen and from only one fruit species.Special fruit jams are classified in:a. Non-pasteurized (min. 68% refractometric extract); andb. Pasteurized (min. 65% refractometric extract); minimum acidity,

expressed in malic acid, is 0.5%.Basic Recipe Seting is done taking into account following elements: -

maintenance, as much as possible, of fruit shape, because this is specific tothese finished products;

• Added sugar, in relation to finished product, must be at 60-65%;this high percentage is needed in order to obtain a rapid and stronggelification and to facilitate conservation of fruit shape;

• A satisfactory gelification cannot generally be obtained withoutpectin addition, at a level of 1-2%, or respectively 10-20% pecticextract (10% refractometric extract);

• Partial (about 40%) inversion of added sugar is necessary.The basic recipe is: 80 kg fruit + 100 kg sugar + 1.6-2.0 kg pectin powder

and 1 kg citric or tartric acid; this will yield about 165 kg of special fruit jamwith 60% added sugar; water quantity to be evaporated is about 18 kg. If thefinished product has to contain 65 % added sugar, the boiling has to becontinued up to evaporation of about 30 kg water, the resulting finishedproduct quantity will be about 153 kg.

Technological flow sheet for manufacturing of special fruit jams is asfollows: Fruit Preparation: sorting, washing, peeling and coring (for apples,pears, quinces), or removal of quetches and stones/pits (for plums, peaches,apricots, cherries) or of short tails (for strawberries and wild berries). Pomacefruits are then cut in slices or quarters.

Boiling with sugar is the most important operation in production ofspecial fruit jams and has as objective to evaporate water until gel formationand partial inversion of sugar. Boiling has to be conducted in such a way asto avoid fruit disintegration, but fruits must be well penetrated with sugar.

By boiling an equilibrium is reached, by osmosis, between sugar solutionand cellular juice. The initial concentration gap between sugar syrup andcellular juice is very high and if the equilibration process is forced, juice comesout of cells and fruit loses its shape and may even disintegrate.

The boiling process accelerates the equilibration, intensity of whichincreases with temperature and boiling time.

Pectin addition shortens boiling and thus delays the equilibration; forthis reason there are different methods for special fruit jams preparation:

• Maintaining fruit in sugar, at ambient temperature, over 8-24 hours;


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fruit to sugar ratio is that indicated in recipe. After this sugarimpregnation, fruits and resulting sugar syrup are brought togetherto boil; toward the end of boiling, pectin, dissolved in warm water,and necessary acid quantity are added.

• Preparation of a very concentrated sugar syrup (at least 75%), inwhich fruit is introduced in order to be boiled. The rest of theoperations are similar to those described in the previous method.— Soft fruit (strawberries, wild berries) can be mixed with sugar

directly in evaporating open kettles, without added water andthen heated gradually up to boiling, which is continued as inprevious method.

Boiling is preferably carried out in small open kettles (50-100 kg) in orderto avoid too long a boiling and fruit disintegration.

Gelification corresponds generally to the reaching of a concentration of65% soluble extract, respectively 68% refractometric extract. Practical test forgelification is done as for jellies and marmalades.

Cooling is a technological step strictly necessary in order to avoid fruitrising to the surface in preservation receptacles. Cooling is done in a doublebottomed water bath in which water circulates at about 80° C.

Filling of receptacles (jars, boxes, glasses, etc.) is carried out and it isnecessary to assure at this stage that the finished product is homogeneous(equal quantities of fruits and gel). Pasteurization is only applied to specialfruit jams with 65 % refractometric extract packed in jars or boxes and isperformed at about 100° C for about 20 min.

Gelification is carried out during product cooling and intensifies duringstorage. Storage must follow the same conditions as for marmalades.

NON GELIFIED SUGAR FRUIT PRESERVES

T ECHNOLOGY OF FRUIT JAM S

Fruit jams are products obtained by boiling of fruits (whole, halves, etc.)with sugar syrup until the reaching a viscous consistency. Jams can be definedas fruits included in a concentrated syrup.

Jams are only prepared from fresh fruits; the usual product range coversthe following species: strawberries, cherries, apricots, wild berries, peaches,plums, raisins, quinces, rose petals, etc.; manufacturing of jams from fruitmixes is not an accepted practice. Standards indicate that fruit jams have toconform with following conditions:

• Fruit or fruit pieces content 45-55%;• Soluble substances, refractometric degree min. 72%;• Acidity (expressed in malic acid) min. 0.7%.Basic Recipe Setting is presented below as an indication:


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100 kg fruits150 kg sugar250 kg35 kg water to be evaporated215 kg jam at about 72% refractometric extractFruit preparation is similar to special fruit jams with the difference that

stone/seed removal is mandatory for all species.Boiling Fruits with Sugar can be achieved by the same three methods

described above for special fruit jams. By boiling a sugar content equilibrationis foreseen and the operation must be conducted in such a way that texture,flavour and colour of fruits be preserved. Foam/scum has to be removedduring boiling.

Generally boiling in concentrated sugar syrup (at least 75%) after aprevious diffusion during 2-4 hours is in practical use. Boiling must to becarried out in small portions (about 15 kg) in order to avoid fruit disintegration.

For some fruit species, boiling has to be conducted in many phases/stepswith “stops” to enable sugar diffusion. At the end of boiling, vanillin at aratio of 125 g for 100 kg jam may be added for some fruits (white cherries,raisins, etc.). At the same time, it is also possible to add citric or tartric acid inorder to avoid the “sugaring” defect.

Cooling of jams, necessary in order to avoid fruit rising to the surface, iscarried out as for special fruit jams.

Filling of receptacles and Storage for jams are performed in same way asfor special fruit jams.

Technology of Special non Gelified Fruit Marmalades

Special non gelified fruit marmalades are products resulting from fruitwithout stones or seeds, sieved or squashed, concentrated by boiling, withoutsugar added and non gelified. Their consistency results from a low watercontent (about 35%) and a high percentage of insoluble substances (5-10%).Sugar the from fruits acts as a preserving agent.

Plum special non gelified fruit marmalade is the product representativeof this category. Other fruit is used very rarely, because they have a reducedsugar content as compared to plums; though there are some countriesproducing special non gelified fruit marmalade from pears or sweet apples.

For plums, the finished product in this category must contain minimum55-60% soluble substances (refractometric extract), rising up to 70% for a highquality product.

Basoc Reco[e Settomg for plums is done in relation with sugar contentof fruits; when this is higher, the product quality is better and the yield ishigher. Thus, if plums with 18% refractometric extract are used, 300-350 kgof fruits are needed for 100 kg finished product.

At the same time, concentration of sugar by boiling, also increases by


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three fold acidity and astringency of this special plum non gelified marmalade;for this reason it is recommended to use only sweet and completely matureplums.

Washing is performed in usual conditions.Pre-Boiling of fruits can be carried out in water or vapour, preferably

with continuous running and has as its objective the softening of tissues.De-Stoning is performed in a pulper.Boiling of the sieved mass is done in double bottom open kettles with a

big evaporation surface or in vacuum evaporators. Boiling in open kettlesenables production of a more tasty slightly caramelized, product; boiling invacuum evaporators has the technological advantages indicated in marmaladeproduction.

At the end of boiling and once of necessary concentration is reached, theproduct is poured directly into receptacles (drums, etc.) and left to cool inorder to form a hard surface layer (crust).

Storage of well closed receptacles is carried out as for marmalade.Special non gelified fruit marmalade can also be prepared from chemically

preserved semi-processed fruit products, but the quality is lower than thatobtained from fresh fruits.

Sometimes dried prunes in a mix with preserved semi-processed productscan be used for plum special non gelified marmalade preparation.

In some countries plum finished products in this category are sweetenedby the addition of maximum 30% sugar, calculated in relation to the finishedproduct.

Technology of Fruit Pastes

These products are obtained in a similar way to marmalades and specialnon gelified marmalades, but have a lower water content (about 25%).Reduction of water content can be achieved by continuing the boiling of theproduct or by natural or artificial drying.

A typical example of fruit paste without sugar added is the apricot paste- “pistil”, etc. which is a concentrated special non gelified fruit marmaladepoured in thin layers and sun dried. An example of fruit paste with sugaradded is quince paste which is a marmalade concentrated by evaporation.Sugar content must be 65%; soluble substances content, 7075 % refractometricextract and acidity at least 0.5% expressed as malic acid. Packing is doneusually in polyethylene sheets and then in boxes or tins; storage conditionsare similar to those for marmalade.

Technology of Fruit Syrups

Fruit syrups are products obtained by dissolving sugar in juices obtainedfrom direct pressing of fruits. Sugar dissolving can be done at roomtemperature or by heating.


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Syrups have to contain 68% soluble substances (refractometric extract)and minimum 1 g/100 ml malic acid. Up to a maximum 10% of sugar can bereplaced by corn syrup. Syrups must be manufactured from the juice of onlyone fruit species.

Juice preparation is carried out at room temperature as described above.Sugar dissolving in fruit juice can be performed by one of the following

methods:a. Boiling in open kettles, done by using the basic recipe:

350-400 kg fruit juice; 650-660 kg sugar; max. 10 kg citric or tartricacid.The juice is brought to boiling and the sugar is dissolved; the totaltime has to be as short as possible in order to avoid flavour lossand a too high sugar inversion degree (optimum inversion degreeis 40%). Acid is added preferably towards the end of boiling.During all boiling processes it is necessary to remove foam/scum.In order to avoid caramelization, the syrup has to be cooled rapidly,and this can be carried out in baths with double bottoms throughwhich are circulated water.One alternative to this method is to boil syrup in closed vessels toavoid flavour losses.

b. Boiling in a vacuum. The basic recipe is the same as above. Sugarand fruit juice are mixed previously in a pre-heating kettle and thentransported to vacuum equipment.Boiling is performed at 50°C and at the end the temperature is raisedslowly up to 65-70°C. The syrup can be cooled directly in vacuumequipment by closing the steam inlet and by increasing the vacuum.In this boiling method it is possible to incorporate a flavourrecuperation device.

c. A continuous process for syrup preparation can be carried out bydissolving components with heat while passing them through ahorizontal cylinder with a screw inside.In the methods where sugar is dissolved by heat, it is also possibleto use chemically preserved juices.In this case it is necessary to first perform the desulphitation ofjuices preserved with SO2. This can be performed by boiling juicewith optional water addition (and before any sugar addition). Highquality syrups are obtained however from fresh juices.

d. Sugar can also be dissolved at room temperature by usingcontinuous flow percolators. These are similar to those used forsalt solution preparation in vegetable canning processes. The juicegoes over a sugar layer and is concentrated progressively untilsaturation (about 65 %). The syrup is then passed through a filtrationsection in the bottom of the percolator.


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Syrup filtration is needed in order to clarify crystals; the filtration ofsyrup is done in warm conditions through cloth.

Filling of syrup in bottles is done in aseptic conditions as much as possiblein order to avoid syrup infection with osmophile yeasts.

Syrup preservation is assured by the high sugar content with respect toa low water activity [unclear].

Storage takes place in well ventilated storage rooms; avoiding sunlightat 10-15°C.

The usual product range is: strawberries, cherries, wild berries, citrusfruits.

T ECHNOLOGICAL ST EPS FOR PROCESSING OF FRUIT JUICESWIT HOUT PULP

Fruit juices must be prepared from sound, mature fruit only. Soft fruitvarieties such as grapes, tomatoes and peaches should only be transported inclean boxes which are free from mould and bits of rotten fruit.

Washing: fruit must be thoroughly washed. Generally, fruit will besubmitted to a pre-washing before sorting and a washing step just aftersorting.

Sorting: removal of partially or completely decayed fruit is the mostimportant operation in the preparation of fruit for production of first qualityfruit juices; sorting is carried out on moving inspection belts or sorting tables.

Crushing/Grinding/Disinteration Step is applied in different ways anddepends on fruit types:

Crushing for grapes and berries;Grinding for apples, pears;Disintegration for tomatoes, peaches, mangoes, apricots.This processing step will need specific equipment which differs from one

type of operation to another.Enzyme Treatment of crushed fruit mass is applied to some fruits by

adding 2-8% pectolitic enzymes at about 50° C for 30 minutes.This optional step has the following advantages: extraction yield will be

improved, the juice colour is better fixed and finished product taste isimproved.

However, for fruit which is naturally rich in pectic substances, thistreatment makes the resulting “exhausted” material useless for industrialpectin production.

Heating of crushed fruit mass before juice extraction is an optional stepused for some fruit in order to facilitate pressing and colour fixing; at sametime, protein coagulation takes place.

Pressing to extract juice.Diffusion is an alternative step for juice extraction and can be carried out

discontinuously or in batteries at water temperature of about 80-85 ° C.


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Juice clarifying can be performed by centrifugation or by enzymetreatment. Centrifugation achieves a separation of particles in suspensionin the juice and can be considered as a pre-clarifying step. This operation iscarried out in centrifugal separators with a speed of 6000 to 6500 RPM.

Enzyme clarifying is based on pectic substance hydrolysis; this willdecrease the juices’ viscosity and facilitate their filtration. The treatment isthe addition of pectolitic enzyme preparations in a quantity of 0.5 to 2 g/l andwill last 2 to 6 hours at room temperature, or less than 2 hours at 50° C, atemperature that must not be exceeded.

The control of this operation is done by checking the decrease in juiceviscosity. Sometimes, the enzyme clarifying is completed with the step called“sticking” by the addition of 5-8 g/hl of food grade gelatine which generatesa flocculation of particles in suspension by the action of tannins. Filtration ofclarified juice can be carried out with kieselgur and bentonite as filtrationadditive in press-filters (equipment).

De-Tartarisationis applied only to raisin juice and is aimed to eliminatepotassium bitartrate from solution. This step can be performed by the additionof 1% calcium lactate or 0.4% calcium carbonate.

Pasteurization of juice can be done for temporary preservation (pre-pasteurization) and in this case this operation is carried out with continuousequipment (heat exchangers, etc.); warm juice is stored in drums or large sizereceptacles (20-30 kg). Pasteurization conditions are at 75°C in continuousstream.

Pasteurization of bottled juice is then carried out just before delivery tothe market; this is performed in water baths at 75° C until the point where thejuice reaches 68° C. In cases when the final pasteurization is done withoutpre-pasteurization and temporary storage, modern methods use a rapidpasteurization followed by aseptic filling in receptacles.

Rapid pasteurization conditions are as follows: temperature about 80° C,over 10-60 sec., followed by cooling; all operations are carried out incontinuous stream.

Preservation under CO2 pressure may be done at a concentration of 1.5%CO2 under a pressure of 7 kg/cm². At the distribution step, proceed at CO2decompression and the juice is then submitted to a sterilising filtration andaseptic filling in receptacles. Preservation by freezing is carried out at about -30° C, after a preliminary de-aeration; storage is at -15 to -20° C.

Production of concentrated juices by evaporation is performed undervacuum (less than 100 mm Hg residual pressure) up to a concentration of 65-70% total sugar which assures preservation without further pasteurization.Modern evaporation installations recover flavours from juices which are thenreincorporated in concentrated juices.

Additional operations for juice manufacturing are the vacuum de-aerationand mixing with other fruit juices or with sugar. For the production of non


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clarified juices the centrifugation is the only specific step, enzyme clarifyingand subsequent filtration being eliminated. The optimum sugar/acid ratiofor the majority of fruit, mainly for pomaces, is 10/1 to 15/1.

Fruit which is rich in carotenoids (apricots, peaches, etc.) is only processedas juices with pulp (“nectars”).

Technological Flow-sheet for Fruit Juices with Pulp (“Nectars”)

This process is divided at industrial scale in two categories of operations:a. Processing for obtaining juices;b. Juice conditioning for preservation;a. Operations in the first category are differ according to the type of

fruit which to be processed.Pomaces (apples, pears) are washed and sorted and then crushed in a

colloid mill; fruit purée is then passed through a screw type heating equipmentwhere direct steam is used as a source of heat. Warm fruit mass is treated ina pulper with a 2 mm screen and then through an extractor similar with theequipment used for tomato juice.

Stone fruits (apricots, peaches, cherries, etc.) after washing and sortingare submitted to steam in a continuous heater, then the warm fruit mass ispassed through a pulper and then an extractor (as mentioned above). Berries(strawberry, wild berries, etc.) are washed, sorted and then crushed, preheatedand then introduced in extractor.

In order to avoid browning and undesirable taste modifications it is usualto add about 0.05% ascorbic acid.

b. Second category type of operations are similar for all fruit species.Partial elimination of cellulose is achieved with a continuouscentrifugal separator; the resulting juice is then processed in orderto adjust sugar and acid content for viscosity.

Sugar (about 8-10%) is added as a syrup (in water or in the juice of samefruit obtained by pressure). Acidity is adjusted with citric or tartaric acid.The adjusted juice is then deaerated under vacuum at about 40° C. This stepaims at avoiding oxidative reactions and vitamin C loss reduction.

An important subsequent step is an intensive homogenisation (underpressure at 150-180 A) in order to obtain particles with dimensions below 100.The homogenised juice obtained is then continuously pasteurized in plate heatexchanger equipment at a temperature of about 130° C, cooled down to about90° C and aseptically packed in receptacles.

The principal characteristics of fruit “nectars” are uniformity and stabilityof the content provided by the advanced disintegration of fruits. Stability canbe obtained by increasing product viscosity by adding pectin for fruit whichis deficient in this component. In order to avoid “separation”, intensivehomogenisation is carried out as described above.

Fruit “nectars” contain all the important components of the original fruit


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and to a large extent maintain their taste and flavour. The sugar/acidity (ascitric acid) ratio is to a large extent determined by the type of fruit and thecorrection applied; for example, this ratio is 30 for apricots, 40 for peaches,160 for pears, etc.

M ANGO AND GUAVA PROCESSING T ECHNOLOGIES

Mango Processing Technologies

Mangoes are processed at two stages of maturity. Green fruit is used tomake chutney, pickles, curries and dehydrated products. The green fruitshould be freshly picked from the tree. Fruit that is bruised, damaged, or thathas prematurely fallen to the ground should not be used. Ripe mangoes areprocessed as canned and frozen slices, purée, juices, nectar and various driedproducts. Mangoes are processed into many other products for home use andby cottage industry.

The mango processing presents many problems as far as industrializationand market expansion is concerned. The trees are alternate bearing and thefruit has a short storage life; these factors make it difficult to process the cropin a continuous and regular way. The large number of varieties with theirvarious attributes and deficiencies affects the quality and uniformity ofprocessed products.

The lack of simple, reliable methods for determining the stage of maturityof varieties for processing also affects the quality of the finished products.Many of the processed products require peeled or peeled and sliced fruit.The lack of mechanised equipment for the peeling of ripe mangoes is a seriousbottleneck for increasing the production of these products.

A significant problem in developing mechanised equipment is the largenumber of varieties available and their different sizes and shapes. The cost ofprocessed mango products is also too expensive for the general population inthe areas where most mangoes are grown. There is, however, a considerableexport potential to developed countries but in these countries the processedmango products must compete with established processed fruits of highquality and relatively low cost.

Green Mango Processing

Pickles

The optimum stage of maturity should be determined for each varietyused to make pickles. There are two classifications of pickles - salt picklesand oil pickles. They are processed from whole and sliced fruit with andwithout stones. Salt is used in most pickles.

The many kinds of pickles vary mainly in the proportions and kinds ofspices used in their preparation. One basic recipe for the study of thepreparation and storage of pickles in oil is as follows:


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Mango pieces 250 g Tumeric powder 2 to 4 g

Salt 60 g Fenugreek seeds 2 to 4 g

Mustard powder 30 g Bengal gram seeds 2 to 4 g

Chili powder 20 g Gingelly oil 20 to 30 g

The ingredients are mixed together and filled into wide-mouthed bottlesof 0.5 kg capacity. Three days later the contents are thoroughly mixed andrefilled into the bottles. Extra oil is added to form a 1-2 cm layer over thepickles.

Chutney

The product is prepared from peeled, sliced or grated unripe or semi-ripe fruit by cooking the shredded fruit with salt over medium heat for 5 to 7minutes, mixed and then sugar, spices and vinegar are added. Cook overmoderate heat until the product resembles a thick purée, add remainingingredients and simmer another 5 min. Cool and preserve in sterilised jars.

Spices usually include cumin seeds, ground cloves, cinnamon, chilipowder, ginger and nutmeg. Other ingredients such as dried fruits, onions,garlic and nuts may be added.

Drying/dehydration. immature fruit is peeled and sliced for sun-drying.The dried mango slices can be powdered to make a product called amchoo.The use of blanching, sulphuring and mechanical dehydration gives a productwith better colour, nutrition, storability and fewer microbiological problems.

Ripe Mango Processing

Puree

Mangoes are processed into purée for re-manufacturing into productssuch as nectar, juice, squash, jam, jelly and dehydrated products. The puréecan be preserved by chemical means, or frozen, or canned and stored in barrels.This allows a supply of raw materials during the remainder of the year whenfresh mangoes are not available.

It also provides a more economical means of storage compared with thecost of storing the finished products, except for those which are dehydrated,and provides for more orderly processing during peak availability of freshmangoes.

Mangoes can be processed into purée from whole or peeled fruit. Becauseof the time and cost of peeling, this step is best avoided but with some varietiesit may be necessary to avoid off-flavours which may be present in the skin.The most common way of removing the skin is hand-peeling with knives butthis is time-consuming and expensive. Steam and lyepeeling have beenaccomplished for some varieties.

Several methods have been devised to remove the pulp from the freshripe mangoes without hand-peeling. A simplified method is as follows: the


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whole mangoes were exposed to atmospheric steam for 2 to 2 1/2 min in aloosely covered chamber, then transferred to a stainless steel tank.

The steam-softened skins allowed the fruit to be pulped by a power stirrerfitted with a saw-toothed propeller blade mounted 12.7 to 15.2 cm below aregular propeller blade. The pulp is removed from the seeds by a continuouscentrifuge designed for use in passion fruit extraction. The pulp material isthen passed through a paddle pulper fitted with a 0.084 cm screen to removefibre and small pieces of pulp.

Mango purée can be frozen, canned or stored in barrels for laterprocessing. In all these cases, heating is necessary to preserve the quality ofthe mango purée. In one process, purée is pumped through a plate heatexchanger and heated to 90°C for 1 min and cooled to 35° C before beingfilled into 30 lb tins with polyethylene liners and frozen at -23.50 C.

In an other process, pulp is acidified to pH 3.5, pasteurized at 90°C, andhot-filled into 6 kg high-density bulk polyethylene containers that have beenpreviously sterilised with boiling water. The containers are then sealed andcooled in water. This makes it possible to avoid the high cost of cans.

Wooden barrels may be used to store mango pulp in the manufacture ofjams and squashes. The pulp is acidified with 0.5 to 1.0% citric acid, heated toboiling, cooled, and SO2 is added at a level of 1000 to 1500 ppm in the pulp.The pulp is then filled into barrels for future use.

Slices

Mango slices can be preserved by canning or freezing, and recent studieshave shown the feasibility of pasteurized-refrigerated and dehydro-cannedslices. The quality of the processed product in all of these procedures will bedependent upon selection of a suitable variety along with good processingprocedures. Thermal process canning of mango slices in syrup is the mostwidely used preservation method.

Beverages

The commercial beverages are juice, nectar and squash. Mango nectarand juice contain mango purée, sugar, water and citric acid in variousproportions depending on local taste, government standards of identity, pHcontrol, and fruit composition of the variety used. Mango squash in additionto the above may contain SO2 or sodium benzoate as a preservative. Otherfood grade additives such as ascorbic acid, food colouring, or thickeners maybe used in mango beverages.

A short description of finished products found in literature is as follows:• Mango juice: prepared by mixing equal quantities of pulp (purée)

and water together and adjusting the total soluble solids (TSS) andacidity to taste (12 to 15% TSS and 0.4 to 0.5% acidity as citric acid);

• Mango nectar containing 25% purée can be prepared using thefollowing procedure.


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Brix of puree

Nectar components 15° 17° 20°

Purée 100 100 100

Sugar 45 43 40

Water 255 257 260

Commercial processing conditions may require the use of a preservative.The pH is adjusted to approximately 3.5 by adding citric acid as a 50%

solution.The time of heat processing will vary with filling temperature, can size

and viscosity of the juice or nectar.Mango squash may be prepared according to flow-sheet; the finished

product may contain 25% juice, 45% TSS and 1.2 to 1.5% acidity and may bepreserved with sulphur dioxide (350ppm) or sodium benzoate (1000 ppm) inglass bottles.

Mango squash simplified flow-sheet.

Ingredients

Mango pulp 900 900

Sugar 900 1100

Citric acid 18 15

Water 900 900

Mangoes are washed, stored, peeled with stainless steel knives. The pulpis prepared by using a pulper with fine sieve (0.025-in); Sugar is mixed withwater and citric acid = syrup; The pulp is added to the syrup and mixed well;The mixture is strained trough cloth; The squash is heated at 85° C and bottlesare filled and closed.

For additional heat treatment bottles may need to be maintained at aproduct temperature of 80°C for 30 minutes if the product is to be processedwithout preservatives. The bottles are then left to cool in water and stored atroom temperature.

Two negative points must be avoided: presence of air bubbles (which isa source of quick deterioration) and separation of squash solids (giving anundesirable appearance). The means to avoid these two phenomena aredescribed in the fruit juices section.

A type of “squash type” beverage may also be manufactured with ‘/apulp + ‘/a water + i/a sugar and pH adjusted to 3.7 by addition of citric acid.Using different sieve sizes affects the quality and reduces air bubbles to acertain extent but homogenisation and de-aeration of purée or squash seemto be important in order to avoid separation and air bubbles. The squashquality is evaluated on the basis of the following characteristics: pH, titrableacidity, soluble solids, ascorbic acid (by 2,6 dichlorophenol indophenolmethod), specific gravity.


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Dried/Dehydrated

Ripe mangoes are dried in the form of pieces, powders, and flakes. Dryingprocedures such as sun-drying, tunnel dehydration, vacuum-drying, osmoticdehydration may be used. Packaged and stored properly, dried mangoproducts are stable and nutritious.

One described process involves as pre-treatment dipping mango slicesfor 18 hr (ratio 1:1) in a solution containing 40° Brix sugar, 3000 ppm SO2,0.2% ascorbic acid and 1% citric acid; this method is described as producingthe best dehydrated product. Drying is described using an electric cabinetthrough flow dryer operated at 60° C. The product showed no browning after1 year of storage.

Drum-drying of mango purée is described as an efficient, economicalprocess for producing dried mango powder and flakes. Its major drawbackis that the severity of heat preprocessing can produce undesirable cookedflavours and aromas in the dried product. The drum-dried products are alsoextremely hydroscopic and the use of in-package desiccant is recommendedduring storage.

Canning

This preservation technology is described in various technological flow-sheets in this bulletin. Mango bar or “fruit leather” is presented in variousflow-sheets.

GUAVA PROCESSING T ECHNOLOGIES

Guava Puree

Guava puree is used in the manufacture of guava nectar, various juice drinkblends and in the preparation of guava jam. The washed sound fruit is firstpassed through a chopper or slicer to break up the fruit and this material is fedinto a pulper. The pulper will remove the seeds and fibrous pieces of tissue andforce the reminder of the product through a perforated stainless steel screen.

The holes in the screen should be between 0.033 and 0.045 in. The machineshould be fed at a constant rate to ensure efficient operation.

The puréed material coming from the pulper is next passed through afinisher. The finisher is equipped with a screen containing holes ofapproximately 0.020 in. The finisher will remove the stone cells from the fruitand provide the optimum consistency to the product.

Perhaps the best way to preserve the guava purée is by freezing and thematerial passing through the finisher can be packaged and frozen with nofurther treatment. It is not necessary to heat the product to inactivate enzymesor for other purposes. The material can be frozen in a number of types ofcartons and cans; however, a fibre box with a plastic bag inside is commonlyused and is probably the less expensive.


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It is also possible to can and heat process the guava purée and this canbe accomplished by heating the purée to 195° F in an open double bottomkettle, filling into cans, closing the cans, inverting the cans for a few seconds,followed by cooling. Cans should be cooled rapidly to approximately 100° Fbefore they are cased and stacked into warehouses.

Guava juice and Concentrate

Guava juice can be used in the manufacture of a clear guava jelly or invarious drinks. A clear juice may be prepared from guava purée that isdepectinised enzymatically. About 0.1% pectin-degrading enzyme is mixedinto the purée at room temperature; heating of the product at approximately120° F will greatly speed the action of the enzyme. After 1 hr. clear juice isseparated from the red pulp by centrifuging or by pressing in a hydraulicjuice press. A batch-type or continuous-flow centrifuge can be used on thedepectinised purée with no further treatment.

The clear juice after centrifuge or after press (and subsequent filtration)can be preserved by freezing or by pasteurization in hermetically sealed cans.For shipment to overseas markets it may be advantageous to concentrate eitherthe purée or the juice.

BANANA AND PLANTAIN PROCESSING T ECHNOLOGIES

Traditional Processing

Most of the world’s bananas are eaten either raw, in the ripe state, or asa cooked vegetable, and only a very small proportion are processed in orderto obtain a storable product. This is true both at a traditional village levelwith both dessert and cooking bananas and when considering the internationaltrade in dessert bananas.

In general, preserved products do not contribute significantly to the diet;however, in some localised areas the products are important in periods whenfood are scarce. Probably the most widespread and important product is flourpreparation from unripe banana and plantains by sun-drying. In Uganda,dried slices known as “mutere” are prepared for storage from green bananas,the dried slices being either used directly for cooking or after grinding into aflour. “Mutere” is used chiefly as a famine reserve and does not feature largelyin the diet under normal conditions.

In Gabon, plantains are sometimes made into dried slices which can bestored and used on long journeys, and plantains are used in Cameroon toprepare dried pieces which are stored and ground as needed into flour for usein cooking a paste known as “fufu”. Dried green banana slices are also used inparts of South and Central America and West Indies for preparing flour.

The other nutritionally important product is beer which is a major productin Uganda, Rwanda and Burundi where green banana utilisation isparticularly high.


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Preservation Methods and Processes

Drying

Both ripe and unripe bananas and plantains are normally peeled andsliced before drying, although banana figs are sometimes prepared from wholeripe fruit. Sun drying is the most widespread technique where the climate issuitable but drying in ovens or over fires is also practiced. In west Africa,plantains are often soaked and sometimes parboiled before drying. The slicesof unripe fruit are normally spread out on bamboo frameworks; or a cementedarea; or on a mat; or on a swept-bare patch of earth; or on a roof; or sometimeson stones outcrops or sheets of corrugated iron.

Oven-drying of ripe bananas is practiced in Polynesia as a mean ofpreserving the fruits, which are then wrapped in leaves and bound tightly tostore until needed. In East Africa a method has been reported that involvesdrying the peeled bananas on a frame placed over a fire for 24 hr before dryingin the sun, to accelerate the process.

Product Stability and Storage Problems

There is little experimental data on the storage life of the traditionallymade banana and plantain products.

Potential for Scaling up of Traditional Processes to Industrial

Level

Many banana products are now produced on an industrial scale, includingthe traditional banana figs and flour, and the processing techniques. One ofthe main problems encountered has been the susceptibility of banana productsto flavour deterioration and discolouration and in the past many productsreaching the market have been of poor quality.

A great deal of research has been directed to overcoming these problems,although however good the resultant products are they cannot compare inflavour and other characteristics with the fresh banana fruit. Indeed, animportant constraint on the large-scale development of banana processing isthe lack of demand for banana products since the fresh fruit is availablethroughout the year in most parts of the tropical world.

The production of beer from banana and plantains has not been scaledup to an industrial level, and while an important product in localised areasof tropical Africa, the market is rapidly declining in favour of European-typebrews produced locally.

Industrial Processing

Products and Uses

The main commercial products made from bananas are canned or frozenpurée, dried figs, banana powder, flour, flakes, chips (crisps), canned slices


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and jams. Banana products can be divided roughly into two types - those fordirect consumption, such as figs, and those for use in food manufacturingindustry, for example purées and powder.

Banana figs, or fingers as they are sometimes known, are usually whole,peeled fruit carefully dried so as to retain their shape, although sometimesthe fruit is sliced or halved to facilitate drying. Banana and plantain chips(crisps) are thinly sliced pieces of fruit fried in oil and eaten as a snack likepotato chips (crisps). The main use of canned slices is in tropical fruit salads.Banana flakes are used as a flavouring or in breakfast cereals. Banana puréefind use mainly in the production of baby foods. Banana flour is said to behighly digestible and is used in baby and invalid foods, but can also be usedin the preparation of bread and beverages. Banana powder is used chiefly inthe baking industry for the preparation and fillings for cakes and biscuits andis also used for invalid and baby foods.

Processing Technology

In general, to obtain a good-quality product from ripe-bananas the fruitis harvested green and ripened artificially under controlled conditions at theprocessing factory. After ripening, the banana hands are washed to removedirt and any spray residues, and peeled. Peeling is almost always done byhand using stainless steel knives, although a mechanical peeler for ripebananas has been developed, capable of peeling 450 Kg of fruit per hour.

The peeling of unripe bananas and plantains is facilitated by immersingthe fruit in hot water. For example, immersion in water at 70-75 ° C for 5 min.has been suggested as an aid for peeling green bananas for flour production,while the peeling of green bananas for freezing has been facilitated byimmersion in water at 93° C for 30 min.

Banana Figs

Fully ripe fruits with a sugar content of about 19.5% are used and aretreated with sulphurous acid after peeling, then dried as soon as possibleafterwards. Various drying systems have been described using temperaturesbetween 50 and 82° C for 10 to 24 hr to give a moisture content ranging from8 to 18% and a yield of dried figs of 12 to 17% of the fresh banana on the stem.

One factory in Australia uses a solar heat collector on the roof to augmentthe heat used for drying bananas. Bananas can also be dried by osmoticdehydration, using a technique which involves drawing water from 1/4-in.thick banana by placing them in a sugar solution of 67 to 70 deg. Brix for 8to 10 hr. followed by vacuum-drying at 65 to 70° C, at a vacuum of 10 mmHg for 5 hr. The moisture content of the final products is 2.5% or less, muchlower than that achieved by other methods.

Banana Puree

Banana purée is obtained by pulping peeled, ripe bananas and then


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preserving the pulp by one of three methods: canning aseptically, acidificationfollowed by normal canning, or quick-freezing. The bulk of the world’s puréeis processed by the aseptic canning technique. Peeled, ripe fruits are conveyedto a pump which forces them through a plate with 1/4-in. holes, then onto ahomogeniser, followed by a centrifugal de-aerator, and into a receiving tankwith 29in. vacuum, where the removal of air helps prevent discolouration byoxidation. The purée is then passed through a series of scraped surface heatexchangers where it is sterilised by steam, partially cooled, and finally broughtto filling temperature. The sterilised purée is then packed aseptically intosteam-sterilised cans which are closed in a steam atmosphere.

Banana Slices

Several methods for canning of banana slices in syrup are used. Best-quality slices are obtained from fruit at an early stage of ripeness. The slicesare processed in a syrup of 25 deg. Brix with pH about 4.2, and in someprocesses calcium chloride (0.2%) or calcium lactate (0.5%) are added asfirming agents. A method for producing an intermediate-moisture bananaproduct for sale in flexible laminate pouches has been developed. Banana slicesare blanched and equilibrated in a solution containing glycerol (42.5%), sucrose(14.85%), potassium sorbate (0.45%), and potassium metabisulphite (0.2%) at90 deg. C for 3 min. to give a moisture content of 30.2%.

Banana Powder

In the manufacture of banana powder, fully ripe banana pulp is convertedinto a paste by passing through a chopper followed by a colloid mill. A 1 or 2% sodium metabisulphite solution is added to improve the colour of the finalproduct. Spray- or drum-drying may be used, the latter being favoured as allthe solids are recovered. A typical spray dryer can produce 70 kg powder perhour to give yields of 8 to 11% of the fresh fruit, while drum-drying gives afinal yield of about 13% of the fresh fruit. In the latter method the moisturecontent is reduced to 8 to 12 % and then further decreased to 2 % by drying ina tunnel or cabinet dryer at 60° C.

Banana Flour

Production of flour has been carried out by peeling and slicing greenfruit, exposure to sulphur dioxide gas, then drying in a counter-currenttunnel dryer for 7 to 8 hr. with an inlet temperature of 75° C and outlettemperature of 45° C, to a moisture content of 8%, and finally milling.

Banana Chips (Crisps)

Typically, unripe peeled bananas are thinly sliced, immersed in a sodiumor potassium metabisulphite solution, fried in hydrogenated oil at 180 to200° C, and dusted with salt and an antioxidant.


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Alternatively, slices may be dried before frying and the antioxidant andsalt added with the oil. Similar processes for producing plantain chips havebeen developed.

Banana Beverages

In a typical process, peeled ripe fruit is cut into pieces, blanched for2 min. in steam, pulped and pectolytic enzyme added at a concentration of2 g enzyme per 1 kg pulp, then held at 60 to 65° C and 2.7 to 5.5 pH for30 min. In a simpler method, lime is used to eliminate the pectin. Calciumoxide (0.5%) is added to the pulp and after standing for 15 min. this isneutralised giving a yield of up to 88% of a clear, attractive juice. In anotherprocess banana pulp is acidified, and steam-blanched in a 28-in Hg vacuumwhich ensures disintegration and enzyme inactivation. The pulp is thenconveyed to a screw press, the resulting purée diluted in the ratio 1:3 withwater, and the pH adjusted by further addition of citric acid to 4.2 to 4.3,which yields an attractive drink when this is centrifuged and sweetened.

Jam

A small amount of jam is made commercially by boiling equal quantitiesof fruit and sugar together with water and lemon juice, lime juice or citricacid, until setting point is reached.

Product Stability and Spoilage Problems

All dried banana products are very hydroscopic and susceptible to flavourdeterioration and discolouration, but this can be overcome to some extent bystoring in moisture-proof containers and sulphiting the fruit before drying toinactivate the oxidases.

The dried products are also liable to attack by insects and moulds if notstored in dry conditions, although disinfestation after drying by heating for 1hr to 80° C or by fumigation with methyl bromide ensures protection againstattack. Banana powder is said to be stored for up to a year commercially andflakes have been stored in vacuum-sealed cans with no deterioration inmoisture, colour or flavour for 12 months.

Banana chips tend to have a poor storage life and to become soft andrancid. However, chips treated with an antioxidant have been storedsatisfactorily at room temperature in hermetically sealed containers up to 6months with no development of rancidity.

Quality Control Methods

In general a good quality product is obtained if fruit is harvested at thecorrect stage of maturity and, where appropriate, ripened under controlledconditions. For example, in the case of banana figs, the fruit should be fullymature (sugar content of 19.5% or above) or the final product is liable to be


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tough and lacking in flavour. However, if over-ripe fruit is used, the figstend to be sticky and dark in colour, so the fruit must be fully yellow but stillfirm.

For banana flour, which is prepared from unripe bananas, the fruit isharvested at three-quarters the full-ripe stage and is processed within 24 hr.prior to the onset of ripening. If less mature fruit is used, the flour tastes slightlyastringent and bitter due to the tannin content. Bananas harvested between85 and 95 days after the emergence of the inflorescence, with a pulp-to-peelratio of about 1.7, were considered to be most suitable for the deep-fat frying.Other criteria suggested for assessing maturity were beta-carotene andreducing sugar content, both of which increase with increasing maturity andpH which decreases as the fruit ripens, and these should be, respectively, about2000 µg/100 g, less than 1.5% and 5.8 or above. Browning was found to occurif the sugar content was higher than 1.5%. The determination of crude fat inprocessed chips is also considered to be a necessary quality control measure.It is important to remove all impurities prior to processing of products, andthis is done by washing to remove dirt and spray residues and control on theprocessing line so that substandard fruit can be removed.

Preparation Methods for Fresh Bananas and Plantains

The main ways of preparing fresh bananas for consumption are boilingor steaming, roasting or baking and frying. Boiling followed by poundinginto “fufu” is also widely adopted in certain areas of the tropics.

Boiling or Steaming

Plantains and bananas are often prepared simply by boiling in water,either in their peel or after peeling, and either ripe or unripe; if unripe, thefruit is scraped thoroughly after peeling to remove all traces of fibrousmaterial. The boiled fruit is eaten alone or more usually accompanied by asauce. This preparation technique is widely used in West Africa.

Roasting or Baking

Unpeeled or peeled fruit, either ripe or unripe, is roasted simply by placingin the ashes of a fire or in an oven. This method is widely used in WestAfrica, East Africa and the South Pacific islands. For example, ripe plantainsare placed unpeeled in an oven and when partly brown and tender, removedand peeled, then replaced in the oven and roasted evenly.

Frying

Ripe or unripe plantains or bananas are often peeled, sliced and cookedin oil, particularly in West Africa and in parts of South America and theWest Indies. Similar products are also made in East Africa. Typically, ripeplantains are peeled, cut into slices or split lengthways, and fried in palm oil


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or with groundnut oil, the pieces being served either hot with a sauce orwith fried eggs, or cold as a snack.

Pounding

Pounding is a process, used particularly in West Africa, for preparingmost perishable staple food crops including plantains, cassava, yams andcocoyams to obtain a paste or dough known as “fufu” (also spelled “foofoo”,“foutou”, “foufou”). The plantains are peeled or boiled and peeled after boilingand pounded in a wooden mortar, the resulting paste normally being eatenwith soup or a spiced sauce of meat and vegetables, but sometimes afterwrapping in leaves and steaming.


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4

Fruit Crop Cultivation andDevelopment

FERTILIZATION IN FLOWERING PLANTS

The development sequence of a typical drupe, the nectarine (Prunus persica)over a 7½ month period, from bud formation in early winter to fruit ripeningin midsummer. A fruit is a ripened ovary. Inside the ovary is one or moreovules where the megagametophyte contains the mega gamete or egg cell.The ovules are fertilized in a process that starts with pollination, whichinvolves the movement of pollen from the stamens to the stigma of flowers.After pollination, a tube grows from the pollen through the stigma into theovary to the ovule and sperm are transferred from the pollen to the ovule,within the ovule the sperm unites with the egg, forming a diploid zygote.

Fertilization in flowering plants involves both plasmogamy, the fusingof the sperm and egg protoplasm and karyogamy, the union of the spermand egg nucleus. When the sperm enters the nucleus of the ovule and joinswith the megagamete and the endosperm mother cell, the fertilization processis completed. As the developing seeds mature, the ovary begins to ripen. Theovules develop into seeds and the ovary wall, the pericarp, may become fleshy(as in berries or drupes), or form a hard outer covering (as in nuts). In somecases, the sepals, petals and/or stamens and style of the flower fall off. Fruitdevelopment continues until the seeds have matured. In some multiseededfruits, the extent to which the flesh develops is proportional to the number offertilized ovules. The wall of the fruit, developed from the ovary wall of theflower, is called the pericarp. The pericarp is often differentiated into two orthree distinct layers called the exocarp (outer layer, also called epicarp),mesocarp (middle layer), and endocarp (inner layer). In some fruits, especiallysimple fruits derived from an inferior ovary, other parts of the flower (suchas the floral tube, including the petals, sepals, and stamens), fuse with theovary and ripen with it. The plant hormone ethylene causes ripening. When

such other floral parts are a significant part of the fruit, it is called an accessoryfruit. Since other parts of the flower may contribute to the structure of thefruit, it is important to study flower structure to understand how a particularfruit forms. Fruits are so diverse that it is difficult to devise a classificationscheme that includes all known fruits. Many common terms for seeds andfruit are incorrectly applied, a fact that complicates understanding of theterminology. Seeds are ripened ovules; fruits are the ripened ovaries or carpelsthat contain the seeds. To these two basic definitions can be added theclarification that in botanical terminology, a nut is not a type of fruit and notanother term for seed, on the contrary to common terminology.

FRUIT CROPS

Passion Fruit

A promising hybrid between purple and yellow-fruited varieties has beenevolved at Chettalli. The hybrid is high yielding and tolerant to leaf spot, rootrot and resistant to root knot nematodes.

Guava

Two soft seeded guava varieties Arka Mridula and Arka Amulya havebeen released.

Annona

One interspecific hybrid in annona named as Arka Sahan has beenreleased which has good keeping quality and high TSS.

Litchi

One selection in litchi has been identified and released from CHES, Ranchiunder the name Swarna Roopa which is resistant to fruit cracking with highTSS. This is the first litchi variety released in the country.

Jujube/Ber

A promising ber selection CHES-1 from variety Umran has been releasedwhich is earlier than Umran, high yielder and escapes insect, pest diseaseproblems and has been christened as Gomati Kirti.

Pomegranate

Two pomegranate hybrid with dark red arils and soft seeded superior toGanesh seedless have been developed and are in the advanced stages oftesting.

Grape

Grape is grown in 42 139 ha with 672.9 thousand tonnes of production.Most of the commercial varieties are introductions from abroad. Two wild


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species, namely, Vitis lanata and V. riparia are reported from northwesternHimalayan foothills. The commercial varieties are both seeded and seedlesstypes.

Seeded Cultivars

Anab-e-Shahi: The origin of this cultivar seems to be a bud sport as ithas a satelite chromosome. It has been one of the most productive cultivargrown in India and yielded over 12-16 tonnes/ha/year. It has attractive largebunch of berries with good shipping quality.

Bangalore Blue: It is reported to be a vinifera × labrusca hybrid. It ismedium in vigour and yield. The bunches are small and compact. The berriesare small to medium and dark blackish purple in colour. The ripening isuniform. Apart from being used for table purpose, it is being extensively usedfor juice and wine making. It is known for its hardiness and resistance todisease for which it finds a suitable place as parent in a breeding programmeaimed at inducing disease resistance.

Black Champa: It is a selection made at the Indian Institute ofHorticultural Research (IIHR), Bangalore. The vines are vigorous with mediumyielding capacity. The seeded grape of excellent quality is suitable for tablejuice and red dessert wine. It is susceptible to cracking and rotting duringrains.

Cheema Sahebi: A selection from open pollinated seedlings of "PandhariSahebi' in India. The vine is vigorous and a very heavy yielder. Bunches arelong, conical and shouldered with medium-sized, oval and pale berries.Shipping quality is poor due to weak pedicellar attachment. It is a late-ripeningcultivar.

Gulabi: It is also known as Karachi, Paneer Drakshi and Muscat. Itresembles Muscat Hamburg of Australia. The vine is medium in vigour andyield; bunches are small and loose with deep purple, small and sphericalberries. It has thick-skinned berries which attribute to good keeping quality.It has a muscat flavour. The ripening is early and fairly uniform.

Seedless Cultivars

Perlette: Berries are medium in size, whitish green and spherical. Fleshis soft and mild muscat flavoured. It has good keeping quality. Small under-developed berries (shot berries) scattered all over the bunch is a major defect.

Pusa Seedless: It is a selection made at the Indian Agricultural ResearchInstitute, New Delhi from unknown origin. It resembles Thompson Seedlessin many characters. Vine is vigorous and medium yielder. Apart from tablepurpose, good quality raisin can also be prepared from it. It has good keepingquality.

Thompson Seedless: It is one of the most commercially important varietyin India. It is a table and a raisin cultivar. It has wide adaptability and has


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performed well in all the grape growing regions of the country. It is mid-season and uniform in ripening.

Vine is medium in vigour, the bunch is medium-large, long, conical tocylindrical, shouldered and compact. The berries are yellowish green to goldenyellow when fully ripe, small and elongated. Eating and keeping quality areexcellent. Berry size is improved through GA application.

Table: Composition of Some Underutilized Fruits in India

Constituents Jujube Aonla Jackfruit Bael Custard

(%) apple

Moisture 81.0 81.2 77.2 61.5 73.6

TSS 13-20 10-14 - - 26.4

Acidity 0.2-0.8 1.4-2.5 - - 0.3

Protein 0.9-1.7 0.5 1.9 1.8 0.8

Carbohydrates 12.8 14.1 18.9 31.8 -

Total sugar 5.4-12.4 4.0-9.8 20.6 - 21.8

Vitamins (mg/100g) 70-165 600 540 IU 931 IU 8.5

(Vit. C) (Vit. C) (Vit. A) (Vit. A) (Vit. C)

Arkavati: It is a hybrid developed at IIHR, Bangalore. It is a high yieldingvariety, suitable for raisin making.

IIHR also released other varieties like Arka Kanchan (seeded), ArkaShyam, Arka Hans, Arka Neelmani (black seedless), Arka Shweta (whiteseedless). One black hybrid Arka Krishna has been released for juice making,while Arka Soma and Arka Trishna are good for wine preparation.

UNDERUT ILIZED T ROPICAL FRUIT S

The underutilized fruits like Jujube or ber (Ziziphus mauritiana), aonlaor Indian gooseberry (Emblica officinalis), jackfruit (Artocarpusheterophyllus), bael (Aegle marmelos), custard apple (Annona squamosa),jamun (Syzygium cuminii), karonda (Carissa congesta), tamarind (Tamarindusindica) are spread over the tropical and subtropical belts of the country. Someof these have good nutritive value and considerable local demand.

Ber (Ziziphus Mauritiana)

Indian ber or jujube belongs to the genus Ziziphus of the Rhamnaceaefamily. Out of about 50 species of the genus, about 20 occur in India. It is thehardiest cultivated fruit tree grown in north Indian Plains.

In the arid Rajasthan state, about 750 ha area was under the crop in 1991.Indian ber starts vegetative growth with commencement of rainy season andsheds its leaves during summer. For good cropping, pruning is essential.Presently, about 70 000 ha is covered under ber in the country.

Cultivar Umran has high yield potential with large sized fruits (av. weight26.8g), whereas cv. Gola, Reshmi, Illaichi have distinct quality attributes.


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Gola is highly drought hardy. Unlike Chinese cultivars, Indian ber cultivarsare not very tolerant to low temperature. Some cultivars, namely, SafedRohtak, Sanaur 5, Jhajja Selection and Katha Phal showed resistance topowdery mildew, which is the major disease in ber.

Bael (Aegle Marmelos)

Bael belongs to family Rutaceae and is an indigenous fruit of India. Thetrifoliate aromatic leaves are used for sacred offering in Hindu religiousfunctions. It is reported to have medicinal value; the unripe fruit is oftenprescribed for diarrhoea and dysentry, while ripe fruit is a tonic, laxative andgood for heart. Fruit is a rich source of carotene and riboflavin. There was nostandard cultivar in bael. In the recent past, some improved cultivars (NB-1,NB-7, NB-9) have been identified. A large genetic diversity still remainsunexplored.

Jackfruit (Artocarpus Heterophyllus)

Jackfruit grows wild in the forests of Western and Eastern Ghats of Indiaand a few species, namely, A.chaplasha, A.hirsutus and A.lakoocha areavailable in nature in Assam, West Bengal in the Eastern India and in theAndaman Islands. Being a cross pollinated plant, propagated mainly by seeds,a wide range of variability is noticed in Jackfruit. There are two broad groups,soft flesh and firm flesh types. The soft flesh types are quite juicy and pulp ishighly scented. So far there is no well defined variety, and in differentlocalities, local varieties are known differently. Local selections have beennamed as Gulabi (rose scented), Champa (flavour like that of Michelia sp.),Hazari (bearing large number of fruits in a tree).

As a result of local survey, some better types have been collected. Sincein India raw jackfruits have good demand as vegetable for culinary purpose,emphasis is also given on fruit characters like thinner rind and soft flesh atpremature stage of fruit development.

A few selections, namely, NJT1, NJT2, NJT3 and NJT4 with large fruitsand excellent pulp quality have been identified for table purpose, while typeslike NJC1, NHC2, NJC3 and NJC4 were found to be better for culinary purpose.North-Eastern region of India produces large quantity of Jackfruit. The stateAssam of in eastern India is reported to have about 8000 ha under Jackfruit,while Tamil Nadu state in south India has a covered area of about 2960 haunder this crop.

Jamun (Syzygium Cuminii)

Jamun belongs to the family Myrtaceae and is a native of India, Burma(Myanmar) and Sri Lanka. The tall tree with evergreen foliage is an excellentroadside tree and very often used as windbreaker. It is widely grown both innorth and south India. Distribution of some economic species of Syzygium.


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Small dark purple coloured fruits with sub-acid spicy flavour are eaten fresh.There is no standard variety in jamun. In north India, a type known as

'Ra Jamun' with big (2-5 cm long fruits) fruits is normally grown. A small(1.5-2.0 cm long and 1-1.5 cm diameter) fruited type is also grown for lateharvesting. A wide range of variability exists in jamun and survey conductedin Pune and Ahmednagar districts in Maharashtra state revealed widevariation in fruit weight (3.5 to 16.5 g), pulp contents (54-85 %),TSS (4.5-17 %) and acidity (0.16 to 0.55 %). Some promising lines have beenselected.

Table : Syzygium Species of Horticultural Interest Found in India

Species Distribution

S. cuminii Indo-Gangetic plains of north India, Tamil Nadu in south,

widely distributed

S. arnottianum Western Ghats, the Nilgiris, Palni and Anamalai Hills

S. bracteatum Western Ghats, Eastern/northeastern India

S. operculatum Grows wild in Nilgiri Hills of Tamil Nadu, Western Ghats

S. aqueum Mainly in Assam, Sikkim and Meghalaya, Eastern/ northeastern

India

S. fruiticosum Grows as an avenue tree, widely distributed

Other Fruits

India grows many other tropical fruit crops. Fruits like guava, litchi,sapota, pomegranate and pineapple are grown commercially. Goodgermplasm exists in these crops and improved cultivars have been released.In custard apple, a few promising cultivars have been identified. At the IIHR,large number of hybrids obtained from different crosses are being evaluated.

In passion fruit, a cultivar named, 'Kaveri' with multiple resistance againstFusarium sp. leaf spot disease and nematodes has been developed from crossesof Passiflora edulis × P. edulis f. flavicarpa. In sapota, Kalipatti, Cricket Balland Kirtibarthi are some popular cultivars, while in guava, Allahabad Sufedaand L-49 are popular. In pomegranate, very fast expansion has taken placeand some excellent, high yielding cultivars like 'Ganesh' G-137 have beenreleased. In a traditional crop like tamarind, several high yielding types havebeen selected. Tamil Nadu state alone covers about 13 820 ha under tamarindand produces about 42 000 tonnes of fruit.

The fruit industry in India has made remarkable progress during the lastthree decades. The area under fruits has increased from 1.22 million ha in1961 to 5.56 million ha in 1994-95. As per FAO Yearbook 1994, India rankedsecond after China with a production of about 33.23 million tonnes. Our sharein the world production of fruits is about 8% and India produces about 65%of the world mangoes and 11% of the world bananas, ranking first in boththe crops.


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Although banana occupies less than 12% of the area under fruits, itcontributes nearly 32% of the total fruit production in the country. Quantity-wise, out of all fruits produced in the country, maximum production is inbanana (32%). The five fruits, mango, banana, citrus, guava and apple, coverabout 75% of the total fruits produced in the country. In less known fruitslike sapota, jujube/ber, aonla and pomegranate, area expansion and productionrise during the recent years is simply spectacular.

PRESENT SITUATION OF DECIDUOUS FRUIT CROP CULTIVATION

CROPS GROWN

India grows crops like apple (Malus pumila Mill.), pear (Pyrus communisBerm.f.), peach/nectarine (Prunus persica (L). Bats. Ch.), plum (Prunus domesticaL.), apricot (Prunus armeniaca L.), sweet cherry (Prunus avium L.) and sourcherry (Prunus cerasus L.) on a commercial scale.

Cultivars

The promising cultivars of different temperate fruits in 3 major deciduousfruit growing States of India. Some relevant information on cultivars andcultivar selection is indicated below:

Apple: Over 700 accessions of apple, introduced from USA, Russia, U.K.,Canada, Germany, Israel, Netherlands, Australia, Switzerland, Italy andDenmark have been tried and tested during the last 50 years. The deliciousgroup of cultivars predominates the apple market. The areas covered underDelicious cultivars are: 83% of the area under apple in H.P., 45% in J&K and30% in U.P. hills. In more recent times improved spur types and standardcolour mutants with 20-50% higher yield potential are favoured. The importantselections are:

• Spur types-Red spur, Starkrimson, Golden spur, Red Chief andOregon spur.

• Colour mutants-Vance Delicious, Top Red, Skyline Supreme.• Low chilling cultivars-Michal, Schlomit.• Early cultivars-Benoni, Irish Peach, Early Shanburry, Fanny.• Juice making cultivars-Lord Lambourne, Granny Smith, Allington

Pippin.• Scab resistant cultivars-Co-Op-12, Florina, Firdous, Shirean.• New Hybrids-Lal Ambri (Red Delicious X Ambri), Sunehari (Ambri

X Golden Delicious), Amred (Red Delicious X Ambri), ChaubatiaAnupam & Chaubatia Princess (Early Shanberry X Red Delicious)developed in India.

In H.P. monoculture of a few cultivars such as Royal Delicious, RedDelicious and Richared have started showing negative impact on the apple


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industry. Serious problems of apple scab disease and outbreak of prematureleaf fall and infestation of red spider mite are causing great concern. U.P. Hills,particularly the Kumaon hills division, have the unique advantage of earlyharvest of apple, mainly due to cultivation of early maturing varieties likeEarly Shanburry, Fanny and Benoni. The early maturing varieties areharvested 2-3 weeks before the arrival of fresh apple from H.P. and J&K, andhence fetch very remunerative prices.

Pear: In pear for higher altitude conditions high chilling requirementvarieties (like Bartlett) are mainly grown. In more recent years, red-colourstrains of pear like Max Red Bartlett, Red Bartlett and Starking are replacingyellow coloured cultivars. In warmer sub-mountainous areas of H.P. andsubtropical Punjab oriental pear cultivars like Baghugosha, Kieffer, China andsand pear Patharnakh are cultivated commercially both for table andprocessing purpose.

Apricot: Generally there are two types of apricot, namely, sweet kerneltype and bitter kernel type. About 81 exotic accessions and 19 indigenouscultivars were collected and evaluated. The local types Halman andRakhaikarpo have been popular, whereas exotic introductions namely, Nari,Kaisha, Shakarpa and New Castle are promising. These cultivars arerecommended for dry cold areas. The USA variety Nugget is self-fruitful andbears sweet and attractive coloured fruits.

Peach: For colder conditions the peach cultivars July Elberta, Elberta,Peshwari, Quetta, Burbank and Stark Earliglo are well adopted. Low-chillingcultivars viz. Flordasum, Flordared, Shan-e-Punjab, Sharbati and Sunred(nectarine) have become popular in subtropical belts of U.P. and Punjab States.

Plum: A large number of cultivars have been introduced into the country.European plums performed better in the hills, while Japanese plums are moreadopted in sub-mountainous lower elevations. Leading cultivar in the hills isSanta Rosa. In the north-Indian plains small fruited cultivars like Titron, KalaAmritsari, Kelsey, and Alubukhara showed better performance. A goodnumber of low-chilling Florida hybrids Sungold, Redgold etc, are underevaluation.

Cherry: Many cultivars of sweet cherry have been introduced fromEurope, USSR and British Columbia. Promising exotic cultivars like BigarreanNapoleon, Black Heart, Guigne Noir for J&K and cultivars like Black TartarianBing, Napoleon (white) Sam, Sue (White), Shella for H.P. have been identified.For warmer climate, cultivars like Summit, Sunburst, Lapins, Compacat andStella have been found to be promising.

Rootstocks

• Apple has been propagated mainly on seedling stocks of apple(Malus pumila Mill). Clonal rootstocks of M and MM series wereintroduced from East Malling Research Station of U.K. and M-9,


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M-26, M-4, M-7, MM-106 and MM-111 were identified as promising.Merton 779 was recommended as a commercial rootstock for applefor Kumaon hills of U.P. However, clonal rootstocks have not foundfavour among the apple growers. In-vitro protocols of M-9, MM-106 and MM-111 have been developed. Clonal rootstocks have beenpreferred only for high density orchards. Four rootstocks, namely,EMLA-111 for drought prone areas, EMLA-7 for slopy land andEMLA-106 for slopy and less clayey soil and EMLA-9 for highdensity planting on irrigated deep soils have been recommended.In pears, seedling stocks of Pyrus pashia (Kainth) is commerciallyused. Clonal rootstock Quince A with semi-vigorous growth hassome promise. Newer clonal rootstocks like Old Home XFarmingdale series and BA 29C are under evaluation.

• For apricot, seedlings of wild apricot have been found to be goodgiving a smooth union and vigorous scion growth. Peach can alsobe tried as a rootstock, particularly for dry and light soils.Myrobolan plum is recommended for high moisture soil conditions.

• Peach is normally grafted on wild peach seedlings, plum and evenon apricot. Wild peach produced healthy and high-yielding plants.For controlling tree size, apricot rootstocks which impart dwarfingmay be used.

• For plum, wild peach and wild apricot are commonly used asrootstocks. Among clonal rootstocks, Myrobolan B. was found tobe most promising. Wild apricot seedlings and wild peach werealso found to be suitable rootstocks for commercial cultivars likeSanta Rosa, Mariposa and Beauty.

• Commercial plantations of sweet cherry were raised mainly onMazzard and Mahaleb rootstocks. Seedlings are raised from latematuring cherry cultivars and stones of Waterloo or Misri cultivarsare often used as rootstocks. Rooting of cherry suckers has beenmade possible with use of rooting hormones like IBA (6000 ppm)in combination with NAA (2000 ppm).

Apple

Although there has been 5-6 fold increase in apple production duringthe last 50 years, the productivity level is still very low (5.56 t/ha). Applecultivation received greater attention by the growers. In H.P, area under appleincreased from 3026 ha in 1960-61 to 78296 ha in 1995-96 with a correspondingincrease in yield. J&K covers about 78007 ha under apple with a productionof 714834 tons. In the U.P. hills (8 districts) apple occupies about 30 per centof the area under fruits and contributes 46.9 percent of fruit production. Thearea covered under apple in U.P. hills is 55200 ha with production of 210000tons of fruits. In the North-Eastern Hills Region, good quality apple is


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produced only in the rain-shadow belts of Arunachal Pradesh (5523 ha),and in Nagaland a very small area (64 ha) has been brought under applecultivation.

About 99 percent of India’s apple area falls under the North Western Hillsregion, covering 6 districts of J&K (Srinagar, Budgam, Pulwama, Anantanag,Baramullah, Kupwara), 6 districts of H.P. (Shimla, Kullu, Sirmour, Mandi,Chamba, Kinnaur) and 8 districts of U.P. (Almora, Nainital, Pithauragarh,Tehri, Pauri, Chamoli, Uttarkashi, Dehradun). In the Northeastern Hills region,good quality apple is grown in a small area in Tawang belt of Kameng districtin Arunachal Pradesh. The Tawang area is basically a rainshadow belt andtherefore, permits a longer period of sunshine and freedom from heavy rains,making it ideal for apple. Apple is also grown in Sikkim and Nagaland butthe production is not a major success. Presently, a small quantity of appleproduced in India is exported, mainly to Bangladesh and Sri Lanka.

Pear

Pear is grown under a wide variety of climatic regimes, ranging fromcold dry temperate hilly conditions to warm humid subtropical conditionson the plains of northern India. Its cultivation is most extensive in J&K State(14012 ha), followed by U.P. (10550 ha). In the plains of Punjab, pear is grownin a specific area (7899 ha), whereas in H.P, it is widespread from the foothillsto the highlands (600-2700 m) in areas experiencing 500-1500 chilling hours.Area, production and yield of apple and pear.

Others

There is no reliable data on area and production of other deciduous fruitcrops. Stone fruits as a group occupy an area of 0.11 million ha, with 0.14million tons production. In H.P about 28 thousand ha are covered under peach,plum, apricot, almond and cherry. In the Northwestern Himalayan region,peach holds greater promise because of its utilization for canning purposes.Peach is grown mainly in low and mid hilly areas (1000-2000 m above msl),except the low chilling cultivars belonging to the Florida group, which canbe grown very well under subtropical conditions.

European plums require more chilling than Japanese plum. Japaneseplums are generally grown in low and mid-hilly areas (1000-6000 m)conditions. The climatic requirement of apricot is almost the same as that ofplum, while cherries require a colder climate (1000 chilling hours below 7°C). Cherry is commercially cultivated in J&K where the hailstorm problem isnot encountered.

In the North-Eastern Hills (NEH) Region, these crops can be successfullygrown in Arunachal Pradesh (Kameng, Siang, Tirap and Lohit districts),Meghalaya (Central plateau of Khasi & Jaintia hills), Manipur (Maram, Tadubi,Mou, Ukhrul) and Nagaland (Mokokchung, Wokhla, Thensang, Kohima,


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Phek districts). The productivity of all the stone fruits is low and estimatedyield of peach is 0.50, 0.73, 2.11 and 2.23 t/ha in H.P, J&K, U.P, and NEHRegions respectively. The productivity of cherry in J&K is approximately1.73 t/ha, while average yield of apricot is 0.42, 0.20 and 0.28 t/ha in H.P, J&Kand U.P. hills respectively.

PHYSIOLOGY OF PRUNING FRUIT TREES

Woody plants are pruned to maintain a desired size and shape and topromote a certain type of growth. Ornamental plants are pruned to improvethe aesthetic quality of the plant, but fruit trees are pruned to improve fruitquality by encouraging an appropriate balance between vegetative (wood)and reproductive (fruiting) growth. Annual pruning of fruit trees alwaysreduces yield, but enhances fruit quality. Pruning increases fruit size becauseexcess flower buds are removed and pruning encourages the growth of newshoots with high-quality flower buds. Pruning improves light penetration intothe canopy, and light is required for flower-bud development, fruit set andgrowth, and red colour development. Pruning also makes the canopy moreopen and improves pest control by allowing better spray penetration into thetree; air movement throughout the canopy is increased, which improvesdrying conditions and reduces severity of many diseases.

This publication describes why plants respond to pruning and other formsof plant manipulation used to train trees. This information applies to all plants,but application to fruit trees is emphasized.

Pruning fruit trees is somewhat of an art based on an understanding ofplant physiology and development. In other words, if we understand howplants grow and how they will respond to different types of plantmanipulations, we can alter vegetative growth and fruiting to obtain treesand fruit with desirable characteristics.

A basic understanding of certain aspects of plant physiology is aprerequisite to understanding pruning. Unlike animals, plants continue toincrease in size throughout their lives. There are only two ways plants cangrow.

Primary growth is the increase in length of shoots and roots, and isresponsible for increases in canopy height and width.

Secondary growth is the increase in thickness of stems and roots.Both types of growth require cell division followed by cell enlargement

and differentiation.

FRUIT TREE PROPAGATION

Fruit tree propagation is usually carried out through asexual reproduction


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by grafting or budding the desired variety onto a suitable rootstock.Perennial plants can be propagated either by sexual or vegetative means.

Sexual reproduction occurs when male pollen from one tree fertilises theovules (incipient seeds) of the flower of another, stimulating the developmentof fruit. In turn this fruit contains a seed or seeds which, when germinated,will become a new specimen. However, the new tree will inherit many of thecharacteristics of both its parents, and it will not grow ‘true’ to the varietyfrom which it came. That is, it will be a fresh individual with manyunpredictable characteristics of its own. Although this is desirable in termsof increasing biodiversity and the richness of the gene pool (such sexualrecombination is the source of most new cultivars), only rarely will such fruittrees be directly useful or attractive to the tastes of humankind. A tendencyto revert to a wild-like state is common.

Therefore, from the orchard grower or gardener’s point of view, it ispreferable to propagate fruit cultivars vegetatively in order to ensurereliability. This involves taking a cutting (or scion) of wood from a desirableparent tree which is then grown on to produce a new plant or ‘clone’ of theoriginal. In effect this means that the original Bramley apple tree, for example,was a successful variety grown from a pip, but that every Bramley since thenhas been propagated by taking cuttings of living matter from that tree, or oneof its descendants.

Methods

The essentials of our present methods of propagating of fruit trees datefrom pre-Classical times. Grafting as a technique was first developed in Chinafrom where it was imported to Greece and Rome. Classical authors wroteextensively about the technical skills of fruit cultivation, including graftingtechniques and rootstock selection. The oldest surviving named varieties offruits date from classical times.

The simplest method of propagating a tree asexually is rooting. A cutting(a piece of the parent plant) is cut and stuck into soil. Artificial rootinghormones are sometimes used to assure success. If the cutting does not die ofdesiccation first, roots grow from the buried portion of the cutting to becomea complete plant. Though this works well for some plants (such as figs andolives), most fruit trees are unsuited to this method.

Root cuttings (pieces of root induced to grow a new trunk) are used withsome kinds of plants. This method also is suitable only for some plants.

A refinement on rooting is layering. This is rooting a piece of a woodthat is still attached to its parent and continues to receive nourishment fromit. The new plant is severed only after it has successfully grown roots. Layeringis the technique most used for propagation of clonal apple rootstocks.

The most common method of propagating fruit trees, suitable for nearlyall species, is grafting onto rootstocks. These are varieties selected for


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characteristics such as their vigour of growth, hardiness, soil tolerance, andcompatibility with the desired variety that will form the aerial part of theplant (called the scion). For example, grape rootstocks descended from NorthAmerican grapes allow European grapes to be grown in areas infested withPhylloxera, a soil-dwelling insect that attacks and kills European grapes whengrown on their own roots. Grafting is the process of joining these two varieties,ensuring maximum contact between the cambium tissue (that is, the layer ofgrowing plant material just below the bark) of each so that they grow togethersuccessfully. Two of the most common grafting techniques are ‘whip andtongue’, carried out in spring as the sap rises, and ‘budding’, which isperformed around July and August.

Apple Rootstocks

Another reason for grafting onto rootstocks is that this enables the growerto determine the tree’s eventual size. Apple tree size classes number one toten in increasing height and breadth. A “1” is a dwarf which can be productiveand as short as three (3) feet with proper pruning. A “10” is the standardsized tree with no dwarfing and will grow to twenty(20) or more feet tall andwide, dependent upon the variety chosen. In general the class range is (1) 10-20% of full size, (2) 20-30%, (3) 30-40% and so forth to size 10 which is 100%of full size.

Apple tree rootstocks are referred to by numbers prefixed by lettersindicating the developer of the rootstock.

“M” designates Malling series developed stocks. East Malling Researchis a pioneer in the development of dwarfing rootstocks. East Malling ResearchStation in Kent, England collected clones of the Paradise stocks from Francein 1912 from which 24 “M” were designated with no particular order to therootstock characteristics other than where they were located in the garden atthe time the numbers were assigned. In other words, M.2 is larger tree thanM.9 while M.27 is smaller than M.26.

“MM” designates Malling-Merton stocks developed from joint breedingprogramme by John Innes Institute, in Merton, England, & East MallingResearch Station in the early 1950s.

The “MM” series was developed primarily to provide resistance to WoollyApple Aphid (Eriosomatinae) infestation.

“EMLA” designates East Malling/Long Ashton research stations who tookthe “M” stocks and developed virus free versions. E.g., EMLA 7 is M 7 with aguaranteed virus free stock. EMLA characteristics are often different from theparent “M” rootstock. Note that nearly all the apple rootstocks in the industryare now virus free.

“CG” or “G” designates Cornell-Geneva stocks which are those developedvia the Cornell & USDA collaboration at the New York AgriculturalExperiment Station in Geneva, NY. The “G” is the old designation. All newer


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stocks are “CG” followed by numbers that actually provide some informationabout the stock. As one might surmise, this is a huge improvement in theclassical naming scheme which has no identification method at all.

Diagram illustrating comparative sizes of apple trees depending onrootstock grafting:

• M.27 Malling 27: A very dwarfing rootstock. Unless the centralleader is supported, the tree will be very small. Often only used asan intermediate stem piece on MM.106 or MM.111. If handled andspaced properly, it can be a very productive stock for a vertical axesystem. Trees can be grown three to four feet tall and produce about45 fruit, roughly 2 pecks, depending on fruit cultivar.

• M.9: Very dwarfing-Reaches a height of 8 to 10 ft (2.4 to 3.0 m),coming into fruit after 3–4 years, reaching full capacity of 50 to 65pounds (23 to 29 kg) after 5 to 6 years. It will grow under averagesoil conditions, but needs a good rich soil to thrive. A good choicewhere space is limited and fertility is high. Permanent staking isrequired, as is routine feeding and watering. Trees on this rootstockalways require leader support. The rootstock is very susceptible tofire blight and can develop burr knots.

• G.41 Geneva 41, released in 2005, produces trees the size of M.9.The rootstock was developed from a cross between M.27 andRobusta 5 made in 1975. Resistant to Crown|Collar|Rootrot(Phytopthora) and fire blight.

• M.26: Dwarfing-Similar to M9 in effect, although somewhat morevigorous and generally stronger, with a higher expected eventualyield of 65–75 pounds (29–34 kg) and height of 8 to 10 ft (2.4 to3.0 m). A good choice where soil quality is average and compactgrowth is required. Comes into fruit after 3-4 years, reaching fullcropping capacity after 5 to 6 years. Staking needed for first fiveyears of its life. It is susceptible to collar rot and fire blight andshould not be planted in a wet site. Certain varieties when graftedonto this rootstock may exhibit signs of graft unionincompatibility(i.e., the union breaks).

• G.11 Geneva 11 is the second release of the Cornell breeding


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programme similar in size to M.26 but more productive. Has theadvantage of being resistant to fire blight and crown rot as well asonly rarely producing suckers or burr knots.

• G.202 Geneva 202(CG 5202) is a semidwarfing rootstock thatproduces a tree in class 5 slightly larger than M.26 and is moreproductive than M.26. It was developed from a cross of M.27 andRobusta 5 to be fire blight and Phytopthora resistant as well ashaving resistance to woolly apple aphids. In a 9-year study withthe scion cultivar of the “Liberty” apple, G.202 was about 50 percentsmaller than M.7 but had much greater production efficiency.

• M.7 Malling 7 rootstock produces a semidwarf tree of Class 6 thatis freestanding in deep well drained soils but in rocky, steep, orshallow soils, it tends to lean. The rootstock may sucker profuselyand is susceptible to collar rot(Phytopthora).

• MM.106: Semi-dwarfing-Sometimes referred to as semi-vigorous,this is the most widely used of rootstocks. It is probably the bestchoice for the average garden under average conditions, beingtolerant of a wide range of soils, and producing a tree with aneventual size of 14 to 18 ft (4.3 to 5.5 m). Trees on this stock beginproducing fruit within three to four years, and yield 90 to 110pounds (41 to 50 kg) after some seven or eight years. MM106 isvery suitable for use with weaker varieties that would produceunder sized bushes with more dwarfing rootstocks. Can be trainedas a half standard tree, but is rather too vigorous for cordons unlessthe soil is poor. Requires staking for the first five years or so of itslife. Trees on MM.106 are highly susceptible to collar rot especiallywhen planted in soils that remain wet(poor percolation).

• M.111 : Vigorous-Not generally suitable for garden scale growing,being both too large and spreading (18-25'), and too slow to comeinto cropping. They are however suitable for growing as specimenstandards in the large garden, or for producing medium sizedbushes on poorer soils. Begins to fruit after six or seven years,reaching full capacity of 160 to 360 lb (73 to 160 kg) after eight tonine years. It is the most cold-hardy rootstock readily available.Planting depth of this rootstock is critical. The union should be nohigher than 1 to 2 inches above the final soil line.

• M.25: Very vigorous-Suitable for a grassed orchard, and to growon as a full standard. Plant 20 ft (6.1 m) apart, makes a tree of 15 to20 ft (4.6 to 6.1 m) or more height and spread, eventually yielding200 to 400 lb (91 to 180 kg) per tree. This rootstock is primarily usedin UK and is rarely seen in USA where M.111 is used for this sizetree.

• Seedling: Very vigorous trees produced on a rootstock grown from


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seed. There is greater variability than with the vegetativelypropagated rootstocks. Apples used for production of seedlingrootstocks include ‘Dolgo’ and ‘Antonovka’, which are bothextremely hardy and vigorous.

That is only a sample of some of the more important current applerootstocks that are available. There are at least a hundred more that have beendeveloped to either provide enhancement or prevent potential damage fromone kind of pest or another.

The problem with growing fruit trees, especially apple trees, is that theyare subject to many different types of damage from bacteria, fungi and insects.The general approach of the commercial industry has been to use as manychemicals as necessary to insure attractive and marketable fruit. The attitude,still prevalent, has been “Who cares? Nobody eats a tree!” but asenvironmental problems increase and the general public pushes for low orno-spray fruit, there has become a commercial need for fruit that does notrequire such intensive spray programmes. This is being achieved, albeit slowly,by rootstocks and trees that are bred to have natural disease and pestresistance.

The Malling series and clones have been standard rootstocks for applesfor many years and remain the standard “workhorses” for the commercialindustry (in USA). However, since most of them are susceptible to diseasesome Malling rootstocks are being replaced by new breeds, including theCornell-Geneva series. One of the newest rootstocks, only releasedcommercially in 2004, is CG5202 (G.202) which adds resistance to the woollyapple aphid(WAA) for the “CG” series of stocks which already has resistanceto the major problems preventing quality production of apples utilizingorganic control systems. Combined with highly resistant trees such as“Liberty” it is showing great potential.

That leads to another characteristic of rootstocks that is or can be bredinto them: environmental adaptability. This may be tolerance to wet|dry soilconditions, acidity|alkalinity of soil or even hot|cold air temperature.

Some new rootstocks based on Siberian Crab Apple are being used incolder areas for more cold tolerance.

The ability of rootstocks to modify or augment characteristics of fruit treesis limited and often disappointing in the final results. It takes ten years to geta full picture of the effects of any one rootstock so a rootstock that appearspromising in the first five years of a trial may fail in the last five years. TheMark (apple) rootstock was such a stock and has now fallen mostly intodisfavour. Another, the G.30, has proved to be an excellent stock forproduction but it was only after a number of years of trials that it was foundto be somewhat incompatible with “Gala” apple(and possibly others) so thatit is now recommended to be staked and wired.

To get a clear picture and push the industry forward, a consortium was


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founded and the so-called “NC-140” trials of rootstocks began. These testmany pome rootstocks in many different sites across the USA and therebyprovide growers, be they backyard or commercial, a clearer picture of whatto expect when growing fruit trees on specific stock, in specific plantingmethods in their specific area of the USA. As one can imagine, this has thepotential for a large economic benefit to both growers and consumers as wellas going a long way to eliminating the need to spray pesticides as frequentlyas is currently required.

Pear Rootstocks

Pears are usually grafted onto quince rootstocks, which produce small tomedium sized trees. Some varieties however are not compatible with quince, andthese require double working. This means that a piece of pear graft-work compatiblewith both the quince rootstock and the pear variety is used as an intermediatebetween the two. If this is not done the pear and the rootstock could eventuallyseparate at the graft. Varieties that require double working include ‘Bristol Cross’,‘Dr Jules Guyot’, ‘Doyenné d’ été’ and ‘Williams Bon Chrétien’.

• Quince C: Moderately vigorous- Makes a bush pear tree about 8to 18 ft (2.4 to 5.5 m) tall, bearing fruit within four to eight years.Suitable for highly fertile soils and vigorous varieties, but not whereconditions are poor. Used for bush, cordon and espalier growing.Old stocks of Quince C may be infected with a virus, so care shouldbe taken to obtain certified virus free stock. If in doubt, use QuinceAn as there is not a great amount of difference in vigour betweenthe two.

• Quince A: Medium vigour- Slightly more vigorous than Quince C,this is the most common variety upon which pears are grafted. Bearsfruit between four to eight years, making a tree of some 10 to 20 ft(3.0 to 6.1 m) in height and spread. Suitable for all forms of peartrees except standards.

Pear stock: Very vigorous- Pears grafted onto pear rootstocks make verylarge standard trees, not suitable for most gardens.

Cherries

Until the 1970s, cherries were grown of the vigorous Malling F12/1,Mazzard (Prunus avium), or Maheleb rootstocks, which required much spaceand time before cropping began, thus the growing of cherries was not arealistic option on a garden scale.

The introduction of the rootstock ‘Colt’ enables trees reaching a maximumheight of 12 to 15 ft (3.7 to 4.6 m) to be grown, and if trained as a pyramid itis possible to restrict growth to about 10 ft (3.0 m). The popular sweet variety‘Stella’ could even be grafted onto a ‘Colt’ rootstock and successfully grownin a pot on the patio.


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Plums

Plum rootstocks include;• Pixy- A dwarfing rootstock, suitable for bush trees planted 8-10 (3

m) apart.• St. Julien A- A semi vigorous rootstock suitable for bush and half

standards planted 12 to 15 ft (3.7 to 4.6 m) apart. Also suitable forpeaches, nectarines and apricots.

• Brompton or Myrobalan B- Suitable for half standards planted 18to 22 ft (5.5 to 6.7 m) apart. Also suitable for peaches, nectarinesand apricots.

• Myro-29C- Semi-dwarf rootstock. Shallow, vigorous, good choicefor hard soils. Somewhat drought tolerant.

• Citation- Semi-dwarf rootstock. Shallow, vigorous, good choice forhard soils. Prefers a wetter soil.

Own-Root Fruit Trees

Some species of fruit are commonly grown on their own roots; new plantsare propagated by rooting, layering, or modern tissue-culture techniques. Inthese cases there are may be no great advantages to using a special rootstockor improved rootstocks are not available. Fig, filbert, olive, pomegranate,gooseberry, bramble, and other fruits are commonly grown without anyspecial rootstock.

FRUIT TREE PRUNING

Pruning fruit trees is a technique that is employed by gardeners to controlgrowth, remove dead or diseased wood or stimulate the formation of flowersand fruit buds. The most economical pruning is done early in the season, whenbuds begin to break, and one can pinch off the soft tissue with one’s fingers(hence the expression “nipped in the bud”). Many home fruit growers makethe mistake of planting a tree, then neglecting it until it begins to bear. Butcareful attention to pruning and training young trees will ultimately determinetheir productivity and longevity. Good pruning and training will also preventlater injury from weak crotches that break under snow or fruit load.

OVERVIEW

To obtain a better understanding of how to prune plants properly, it isuseful to have some underlying knowledge of how pruning works, and howit affects the way in which plants grow.

Plants form new tissue in an area called the meristem, located near thetips of roots and shoots, where active cell division takes place. Meristem growthis aimed at ensuring that leaves are quickly elevated into sunlight, and that


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roots are able to penetrate deeply into the soil. Once adequate height andlength is achieved by the stems and roots, they will begin to thicken to givesupport to the plant. On the shoots, these growing tips of the plant areknown as apical buds. The apical meristem (or tip) produces the growthhormone auxin, which not only promotes cell division, but also diffusesdownwards and inhibits the development of lateral bud growth which wouldotherwise compete with the apical tip for light and nutrients. Removing theapical tip and its suppressive hormone allows the lower dormant lateral budsto develop, and the buds between the leaf stalk and stem produce new shootswhich compete to become the lead growth.

Manipulating this natural response to damage (known as the principleof apical dominance) by processes such as pruning (as well as coppicing andpollarding) allows the horticulturist to determine the shape, size andproductivity of many fruiting trees and bushes. The main aim when pruningfruit trees is usually to obtain a decent crop of fruit rather than a tree with anabundance of lush yet unproductive foliage.

Unpruned trees tend to produce large crops of small, worthless fruit oftendamaged by pests and diseases, and much of the crop is out of reach at thetop of the tree.

Branches can become broken by the weight of the crop, and the croppingmay become biennial (that is, only bearing fruit every other year). Overprunedtrees on the other hand tend to produce light crops of large, flavourless fruitthat does not store well. Pruning is therefore carried out to achieve a balancebetween shoot growth and fruit production.

Formative Pruning of Bush Trees

Formative pruning of apple and pear trees (the pome fruits; the stonefruits such as cherries, plums, gages, etc., have different requirements andshould not be pruned during the dormant months) should be carried outduring the dormant winter months between November and March (or Juneand September in the southern hemisphere) and during the early years of thetree’s life to develop a strong framework capable of bearing the weight of thecrops that will be borne in later years. This involves hard pruning, althoughin later years pruning will be lighter and carried out to encourage fruiting.

One year old tree Two year old tree


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Three year old tree Four year old tree

Maiden Tree

A maiden whip (that is, a one year old tree with no side shoots) shouldbe pruned to a bud with two buds below it at about 80 cm from the groundimmediately after planting to produce primary branches during the firstgrowing season. A feathered maiden (that is, a one year old tree with severalside branches) should have its main stem pruned back to three or four strongshoots at 80 cm from the ground. Side shoots should be shortened by twothirds of their length to an upward or outward facing bud. Lower shootsshould be removed flush with the stem.

Two Year

Remove any lower shoots and prune between three and five of the bestplaced shoots by half to an upwards or outwards facing bud to form whatwill become the tree’s main structural branches. Remove any inwards facingshoots.

Three Year

Prune the leading shoots of branches selected to extend the frameworkby half to a bud facing in the desired direction. Select four good laterals to fillthe framework and shorten these by a half. Prune any remaining laterals tofour buds to form fruiting spurs.

Four Year

The tree will have begun to fruit and only limited formative pruning isnow required. Shorten leaders by one third and prune laterals not requiredto extend the framework to four buds.

Five year and Onwards

The tree is considered to be established and should be annually pruned.

Pruning the Cropping Tree

Before pruning it is important to distinguish between spur bearing andtip bearing varieties. The former, which is the most common type, bear most


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of their fruit on older wood, and include apples such as Cox’s Orange Pippin,James Grieve and Sunset, and pears such as Conference, Doyenne du Commiceand Williams Bon Chretien. Tip bearers on the other hand produce most of theirfruit buds at the tips of slender shoots grown the previous summer, andinclude the apples Worcester Pearmain and Irish Peach, and the pears such asJargonelle and Josephine de Malines. There are basically three types of pruningthat are applied once the main shape of the tree has been established.

Renewal Pruning

• Spur pruning:Spur bearing varieties form spurs naturally, but spurgrowth can also be induced.

• Renewal pruning: This also depends on the tendency of many appleand pear trees to form flower buds on unpruned two year oldlaterals. It is a technique best utilised for the strong laterals on theouter part of the tree where there is room for such growth. Pruninglong neglected fruit trees is a task that should be undertaken overa lengthy period, with not more than one third of the branches thatrequire removal being taken each year.

• Regulatory pruning: This is carried out on the tree as a whole, andis aimed at keeping the tree and its environment healthy, eg, bykeeping the centre open so that air can circulate, removing dead ordiseased wood, preventing branches from becoming over crowded(branches should be roughly 50 cm apart and spurs not less than25 cm apart along the branch framework), and preventing anybranches from crossing.

Pruning of tip Bearers

Tip bearers should be pruned lightly in winter using the regulatorysystem. any maiden shoots less than 25 cm in length should be left untouchedas they have fruit buds at their tips. Longer shoots are spur pruned to preventover-crowding and to stimulate the production of more short tip bearingshoots the following year. Branch leaders are ‘tipped’, removing the top threeor four buds to a bud facing in the desired direction to make them branch outand so produce more tip bearing shoots.

PLANT GROWTH

Meristems are regions of cell division and there are two types of plantmeristems. An apical meristem is located at the tip of every shoot and root.As cells divide in these apical meristems, the shoots and roots elongate ascells are piled one on another. Behind the region of cell division is a region ofcell differentiation, where cells enlarge and differentiate into various tissues.In the axil of each leaf is a small apical meristem called an axillary meristem


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that forms an axillary bud, which usually remains dormant until well afterthe subtending leaf is fully developed. An axillary bud may remain dormantor develop into a lateral branch or a flower.

There are two distinct layers of meristematic tissue within the stem orroot responsible for secondary growth, the vascular cambium and the corkcambium. The vascular cambium is a cylinder of specialized cells, usuallyfive to ten cells thick, running the length of the plant, including the roots, andis responsible for the radial growth of plant parts. Phloem cells are producedto the outside of the cambium and xylem cells are produced to the inside ofthe cambium. Downward transport of sugars, nutrients, and hormones fromthe top of the tree to the roots occurs in the phloem tissue. Xylem cells aretube shaped, become hollow and die to form a pipe-like system through whichwater, hormones and mineral nutrients move from the roots to the top of thetree. Most of the radial growth of woody plants is due to activity of the vascularcambium, but a small amount results from activity in another lateral meristem,the cork cambium, located outside the vascular cambium.

The cork cambium together with the cork cells, constitute the periderm:a protective layer of suberized dead cork cells forming the bark. Suberizationis the impregnation of cell walls of cork tissue with a fatty substance calledsuberin. Each season new layers of cells are produced and appear as growthrings when viewed in cross-section. Over time, the xylem cells at the centreof the trunk or limb are crushed and become nonfunctional as transport pipes,but they do provide structural support to hold the plant upright. Whilegrafting it is important to line up the cambiums of the scion and the rootstockto ensure a successful graft union.

BUDS

Buds are important to the vegetative and reproductive growth of trees.Fruit tree training and, to a lesser extent, pruning primarily involves budmanipulation. Buds are actually undeveloped shoots. When a vegetative budis sliced longitudinally during the winter and viewed under magnification,the apical meristem at the tip, leaf primordial (developing leaves), axillarymeristems, developing axillary buds, and procambial tissue (tissue that willdevelop into the cambium) are all visible.

Buds on fruit trees usually have about seven leaves and initial shootelongation in the spring results from cell expansion. During late June and Julysome of the shoot apices will flatten out and develop into flower buds. Flowerbuds are actually modified shoots and the various flower tissues are actuallymodified leaves. Although the process of switching from vegetative toreproductive buds is not fully understood, hormones that can be influencedby environmental factors, stresses, and plant nutrition control the process.

There are several things we can do to influence whether or not a budbecomes a flower bud or remains vegetative. In general, factors that favour


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rapid growth, such as high nitrogen levels in the shoot tissues, inhibit thedevelopment of flower buds. Applying growth-promoting plant growthregulators such as gibberellins usually inhibits flower-bud induction, whereasethylene may promote flower-bud development. Mild stresses such as shootbending and water stress may also promote flower-bud development.

Producing annual crops of high-quality fruit requires a balance betweenreproductive and vegetative growth. Fruit producers use various techniques,including pruning, branch bending, and plant growth-regulator sprays, tomanipulate tree growth and flowering. Often these techniques affect buddormancy, so knowledge of buds and bud dormancy is essential if we are tounderstand how pruning influences tree growth. It is also important to beable to identify the different types of buds on a tree, especially to distinguishbetween flower and vegetative buds.

Buds may be classified as to location, contents, or activity. Classificationby content Several types of buds commonly develop on fruit trees. Vegetativebuds only develop into leafy vegetative shoots. Flower buds produce onlyflowers. Stone fruit trees (peach, nectarine, apricot, plum, and cherry) producevegetative buds and flower buds. Apple and pear trees produce vegetativeand mixed buds. Both leafy shoots and flowers emerge from mixed buds.

Classification by Location

Terminal buds are located at the tip of a shoot. On stone fruit treesterminal buds are vegetative buds. Terminal buds on apple and pear treesare usually vegetative; however, some varieties such as Rome Beauty producemixed buds terminally and are referred to as tip bearers or terminal bearers.Most mixed buds on apple and pear trees are formed terminally on short,less than sixinch, shoots that terminate with a rosette of leaves. These shortshoots are called spurs. Lateral buds form in the axils of leaves and are oftenreferred to as lateral buds or axillary buds. On stone-fruit trees, lateral budsmay be either vegetative or flower. Nodes on one-year-old shoots may haveone to three buds, some of which may be flower buds and others vegetativebuds. Flower buds are larger with tips that are relatively round, whereasvegetative buds are small, narrow, and pointed. In the case of apple and peartrees, lateral buds on the previous season’s growth are usually vegetative.However, lateral buds on some varieties, especially on the dwarfing rootstocks,may be mixed buds.

Classification by Arrangement on the Stem

The bud arrangement influences the arrangement of a fruit tree’s branchesand thus the tree’s shape and how easy it is to manage. A node is the joint ona stem where a leaf is or was attached. Axillary buds are located in the axisabove where a leaf is attached to the stem. In apples there is usually only oneleaf per node, whereas three leaves often arise from a node on peach shoots.


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When a leaf falls in the autumn, a leaf scar remains just below the axillarybud. Buds are opposite when there are two at the same node but on oppositesides of the stem. Forsythia is an example of a plant with opposite buds. Budsare alternate when there is only one from each node and no one bud is on thesame side of the stem as the one next above or below it. Deciduous fruit treeshave buds that spiral along a shoot. The spiraling three-dimensionalarrangement of leaves around a stem is known as Phyllotaxy and is expressedas a fraction, where the numerator is the number of turns to get to a leafdirectly above another and the denominator is the number of buds passed.

Classification by Activity

Buds are dormant when they are not visibly growing. When shootsdevelop around large pruning cuts, they usually are sprouting from dormantbuds. Adventitious buds form irregularly on older portions of a plant andnot at the stem tips or in the leaf axils. They form on parts of the root or stemthat have no connection to the apical meristems. They may originate fromeither deep or peripheral tissues.

For example, shoots often arise from adventitious buds growing fromcallus tissue around wounds. Root suckers (vigorous upright shootsdeveloping from the roots) develop from adventitious buds on the roots.

FRUIT DEVELOPMENT

Ethylene production is largely pre-determined in both time and amountby the genetics of the fruit and, depending on when the fruit blossoms andthe climate, will determine to a large degree the development of the respiratoryclimacteric. During fruit development, respiration (i.e., the generation ofcarbon dioxide), which is a measure of metabolic activity, declines graduallythroughout the season until several weeks before it ripens where it reacheswhat is known as a preclimacteric minimum. At this point, the metabolicfunctions of the fruit are in a near resting stage in preparation for a burst ofmetabolic activity signifying ripening. During ripening both carbon dioxideand ethylene increase significantly. The main developmental stage of the fruitis referred to as maturation, in which photosynthate is converted to starch.The ripening phase is when the starch is converted to sugar. Senescence isthat stage in which the membrane functions break down due to degradationof lipid bilayers leading to cell damage and necrosis.

Optimum harvest is a subjective measurement defined as a fruit withgood keeping quality and good eating quality. If picked too early during thematuration stage, insufficient starch will be converted to sugar and the fruitwill keep well enough, but the eating quality will be poor. On the otherhand, if the fruit is picked too late, there will be insufficient starch and acidreserves for metabolic maintenance in storage, but the eating quality will be


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good. Therefore, the optimum timing is critical to the proper storage (andmarketing) of apples. Researchers throughout the world have spent decadesdefining the optimum time of harvest for long-term CA storage and yet, asnew varieties enter the marketplace, optimums must be redefined for eachindividual cultivar.

ETHYLENE PRODUCTION

After the respiratory preclimacteric minimum comes the respiratoryclimacteric. This is the point at which the fruit will generate a high, sustainedrespiration and ethylene biosynthesis. It occurs at different times for differentcultivars. For example, a Yellow Transparent apple, which ripens in early July,has a very quick respiratory climacteric and may ripen within a few days. Infact, there are times when I have gone out one day and seen green fruit on thetree and two days later, these fruit are yellow and on the orchard floor. Therespiratory climacteric of this apple is quick and peak is high. On the otherhand, a Delicious apple, which ripens sometime in mid-September, has asomewhat longer climacteric period. This fruit may develop a respiratoryclimacteric over a period of 10 days, for example. This is advantageous to agrower because it allows time to harvest all of the fruit without being soconcerned that the fruit will ripen early and even drop from the tree. Further,there are cultivars that ripen later, such as Fuji, Braeburn, or Granny Smith.These cultivars in turn have an even broader climacteric and the peak ofrespiration (when similarly measured) is lower than in the previous scenarios.

Consider, for example, ethylene from the cultivar Braeburn. In one of ourtrials, fruit was picked over a period of 10 weeks beginning around August15. If we measure the ethylene from the core by sampling with a syringe 24hours after the fruit has been harvested, we see a very low ethylene productionwithin the fruit tissue—generally less than 2 ppm. On the other hand, if wewait for four days before sampling the core gases of the fruit, we seesignificantly higher levels of ethylene reaching about 10 ppm at proper harvest.Waiting for seven days after the fruit is harvested before sampling, results inethylene values in the 60-70 ppm range at harvest time. This suggests thatdelaying cooling (storage) of the fruit after it has been picked hastens theripening process and, therefore, is deleterious to the condition of the fruit outof storage. This is important because often times a grower will harvest hisfruit in bins and it may stay in his orchard or on the warehouse receivingdock before it is properly cooled. The longer the delay between harvest andstorage the shorter will be the storage life and the poorer the condition of thefruit after it is removed from storage.

SAM PLING FRUIT ET HYLENE

Clearly, the accurate measurement of ethylene in apples is vital to theirproper storage and therefore their condition out of storage. But with so


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many fruit (100 million boxes of roughly 100 apples each in WashingtonState alone, and at least 4 times that throughout the world) the problem hasbecome not the accuracy of sampling, but the unfathomable number ofsamples to assess.

Early efforts to analyse gas samples used a bulk approach. A bushel ofapples would be placed in a large glass container and a sample of theheadspace gas would be withdrawn and sampled. If each apple were verysimilar, this approach would accurately depict the physiological state of theindividual fruit and, therefore, the proper regime for optimum storage. Thisis hardly the case. Data obtained from this method was qualitative, however,because there always exists the possibility that one apple could be riper thanthe others, thereby generating most all the ethylene. Thus, although all of theother fruit could have extremely low ethylene levels, the single mature applewould indicate the “average” ethylene was quite high. Because there aredifferences due to size, colour, tree position, stress, variety, rootstock, soil,and a host of other factors, the best that can be said of this method is that itwould always overestimate the average ethylene production.

Individual apples were then evaluated for ethylene production. The mostcommon method was to insert an 18-gauge needle into the apple through thecalyx end extending through to the core. A 0.5 to 1.0 mL sample of gas couldbe withdrawn and subsequently analysed by gas chromatography. (Routineanalysis of ethylene by megabore gas chromatography is sensitive to the tenparts per billion range.) By increasing the number of samples and examiningthe variability among samples, one could obtain a more accurate picture ofthe physiological state of the part of the orchard sampled. Harvest decisionscould then be based on both the amount of ethylene being produced as wellas on the degree of variation of samples. High ethylene blocks (experimentalsites within and orchard) with high variability might well indicate that veryfew fruit are producing significant amounts, whereas, high ethylene blockswith little variability might indicate the entire block is ripening more evenly.The concern with this method lies in not knowing the physiological meaningof a gas sample taken from the fruit centre. Again, there are differences due,for example, to size of seed cavity, amount of water in the fruit, amount ofinterstitial space, cell density and the amount of wounding from the needleinsertion. Generally, any damage to the fruit tissues induces ethylenebiosynthesis.

The method presently under design of assessing individual fruit ethyleneis to place each apple in a small, 3-liter Plexiglas chamber with a low flow ofscrubbed air. Micro-processors may sample the effluent gas as often asrequired 24 hours a day. This takes a single person about 1 hour to set up thesystem capable of analysing gas composition of hundreds of apples—a processthat manually takes about 2 to 3 minutes per sample. The greater number ofsamples increases the likelihood that apples will reach the consumer with


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optimum quality.What is needed is a method to assess quickly and accurately the ethylene

generated by the whole apple, or one that uses part of the fruit that is mostdirectly correlated with the physiological stage of fruit maturity. As forsampling a portion of tissue, it almost seems as though Heisenberg’s principalis at work here in that any invasive action to the fruit will change itsphysiological stage and response.

Perhaps the closest thing the apple industry has to assessing individualfruit maturity is in the fruit sorting process. In modern fruit packingwarehouses individual fruit are mechanically sorted into weight categoriesand optically scanned for colour sorting. Not far away are sensors for inlinedetermination of firmness, sugar content and internal disorders. Practicallyeverything can be determined about an individual fruit without damaging it.So far, however, only ethylene gives a meaningful picture of the physiologicalstage of ripeness. Thus, the problem remains; how does the apple industrynondestructively assess ethylene of 10 billion apples.

INHIBIT ING ET HYLENE BIOSYNT HESIS

Abbott Laboratories has recently developed a new chemical tool for usein apple production. AVG (aminoethoxyvinylglycine) was discovered in 1976by researchers at Hoffmann-LaRoche, but it wasn’t until the last few yearsthat it was made commercially available. This compound is a substitutedamino acid produced by a streptococcal mold and is specifically targeted toinhibit the enzymatic production of ACC, which is the precursor of ethylene.In 1980, Williams in Wenatchee showed that AVG could be used to inhibitinternal ethylene production thereby reducing fruit abscission, but could notbe used to compensate for external ethylene, no matter the source. In 1981,we did some experiments on Golden Delicious apples, in which we took fruitthat was harvested at optimum harvest time and dipped them in solutionscontaining 0, 100, 200, or 400 ppm AVG (Curry, et al.).

These fruit were stored in Plexiglas chambers and the ethylene and carbondioxide were measured daily for a period of seven weeks. Ater about 10 days,the untreated fruit showed an increased rate of respiration that coincidedwith the climacteric rise. For this treatment, ethylene exceeded 50 ppm for theremainder of the study. Fruit dipped in 100 ppm AVG had a respiratoryclimacteric delayed about six weeks. At seven weeks, ethylene levels wereabout 20 ppm and by the ninth week, ethylene had not exceeded 30 ppm. At200 ppm, it took approximately nine weeks to see a slight increase in carbondioxide and at that time, ethylene was approximately 4 ppm. Lastly, at 400ppm, Golden Delicious apples dipped after harvest never showed an increasein respiration and the ethylene levels were near zero, even at nine weeks afterharvest. At the end of the nine weeks, the control apples were yellow andshriveled whereas apples dipped in AVG were still green and noticeably firmer.


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In another trial, Williams (1980) treated Delicious apples with pre-harvestapplications of AVG approximately three days before harvest. These fruit werestored in regular cold storage and after three weeks, showed no differencefrom those that were not treated with AVG. By 16 weeks, however, differencesbegan to occur. Firmness of untreated apples was 13.9 pounds, whereas thosetreated with 450 ppm AVG three days before harvest showed an averagefirmness of 15.2. Thirty weeks after harvest control fruit had a firmness of12.8 pounds, whereas those treated with AVG were a full pound firmer.

TYPES OF FRUIT

SEEDLESS FRUIT S

Seedlessness is an important feature of some fruits of commerce.Commercial cultivars of bananas and pineapples are examples of seedlessfruits. Some cultivars of citrus fruits (especially navel oranges), satsumas,mandarin oranges table grapes, grapefruit, and watermelons are valued fortheir seedlessness.

In some species, seedlessness is the result of parthenocarpy, where fruitsset without fertilization. Parthenocarpic fruit set may or may not requirepollination. Most seedless citrus fruits require a pollination stimulus; bananasand pineapples do not. Seedlessness in table grapes results from the abortionof the embryonic plant that is produced by fertilization, a phenomenon knownas stenospermocarpy which requires normal pollination and fertilization.

Seed Dissemination

Variations in fruit structures largely depend on the mode of dispersal ofthe seeds they contain. This dispersal can be achieved by animals, wind, water,or explosive dehiscence.

Some fruits have coats covered with spikes or hooked burrs, either toprevent themselves from being eaten by animals or to stick to the hairs,feathers or legs of animals, using them as dispersal agents. Examples includecocklebur and unicorn plant.

The sweet flesh of many fruits is “deliberately” appealing to animals, sothat the seeds held within are eaten and “unwittingly” carried away anddeposited at a distance from the parent. Likewise, the nutritious, oily kernelsof nuts are appealing to rodents (such as squirrels) who hoard them in thesoil in order to avoid starving during the winter, thus giving those seeds thatremain uneaten the chance to germinate and grow into a new plant awayfrom their parent.

Other fruits are elongated and flattened out naturally and so become thin,like wings or helicopter blades, e.g. maple, tuliptree and elm. This is anevolutionary mechanism to increase dispersal distance away from the parent


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via wind. Other wind-dispersed fruit have tiny parachutes, e.g. dandelion andsalsify.

Coconut fruits can float thousands of miles in the ocean to spread seeds.Some other fruits that can disperse via water are nipa palm and screw pine.

Some fruits fling seeds substantial distances (up to 100 m in sandbox tree)via explosive dehiscence or other mechanisms, e.g. impatiens and squirtingcucumber.

Uses

Many hundreds of fruits, including fleshy fruits like apple, peach, pear,kiwifruit, watermelon and mango are commercially valuable as human food,eaten both fresh and as jams, marmalade and other preserves. Fruits are alsoin manufactured foods like cookies, muffins, yoghurt, ice cream, cakes, andmany more. Many fruits are used to make beverages, such as fruit juices(orange juice, apple juice, grape juice, etc) or alcoholic beverages, such as wineor brandy. Apples are often used to make vinegar. Fruits are also used forgift giving, Fruit Basket and Fruit Bouquet are some common forms of fruitgifts.

Many vegetables are botanical fruits, including tomato, bell pepper,eggplant, okra, squash, pumpkin, green bean, cucumber and zucchini. Olivefruit is pressed for olive oil. Spices like vanilla, paprika, allspice and blackpepper are derived from berries.

Nutritional Value

Fruits are generally high in fibre, water and vitamin C. Fruits also containvarious phytochemicals that do not yet have an RDA/RDI listing under mostnutritional factsheets, and which research indicates are required for properlong-term cellular health and disease prevention. Regular consumption of fruitis associated with reduced risks of cancer, cardiovascular disease, stroke,Alzheimer disease, cataracts, and some of the functional declines associatedwith aging.

Non-food Uses

Because fruits have been such a major part of the human diet, differentcultures have developed many different uses for various fruits that they donot depend on as being edible. Many dry fruits are used as decorations or indried flower arrangements, such as unicorn plant, lotus, wheat, annual honestyand milkweed. Ornamental trees and shrubs are often cultivated for theircolourful fruits, including holly, pyracantha, viburnum, skimmia,beautyberry and cotoneaster.

Fruits of opium poppy are the source of opium which contains the drugsmorphine and codeine, as well as the biologically inactive chemical theabainefrom which the drug oxycodone is synthysized. Osage orange fruits are used


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to repel cockroaches. Bayberry fruits provide a wax often used to makecandles. Many fruits provide natural dyes, e.g. walnut, sumac, cherry andmulberry. Dried gourds are used as decorations, water jugs, bird houses,musical instruments, cups and dishes. Pumpkins are carved into Jack-o’-lanterns for Halloween. The spiny fruit of burdock or cocklebur were theinspiration for the invention of Velcro.

Coir is a fibre from the fruit of coconut that is used for doormats, brushes,mattresses, floortiles, sacking, insulation and as a growing medium forcontainer plants. The shell of the coconut fruit is used to make souvenir heads,cups, bowls, musical instruments and bird houses.

Fruit is often also used as a subject of still life paintings.

CONSTRAINTS IN DECIDUOUS FRUIT PRODUCTION

Large number of old orchards (more than 30 years old) are showingdecline in terms of growth and fruit yield. Such old trees do not produceadequate extension growth. Large scale replanting is therefore needed.

Delicious group of cultivars constitute the major share (about 83% in H.P.)of apple production in the country. These cultivars are self unfruitful and needcross pollination to ensure good fruit set. Interplanting pollinizer cultivars(Golden Delicious, Jonathan, Red Gold, Lord Lambourne etc.) in theproportion of 25 to 33 percent is necessary for good fruit set, and choice ofwrong pollinizers and their inadequacy in number often result to lowproductivity.

In many countries, Delicious group has been replaced or is in the processof replacement with more promising cultivars. The need for injecting newblood into the apple industry through spread of new cultivars (spur types,colour mutants, strains of Gala, Red Fuji; scab resistant cultivars, bud sportselections of Royal Delicious, and some of the promising hybrids) is urgentlyfelt. Some of the spur type and coloured mutants are already popular withfarmers and high density planting has also caught the imagination ofdevelopmental departments and agencies both in H.P. and J&K. The researchsystem has already identified Early, Mid and Late cultivars for different agro-climatic regions. The low chilling cultivars of stone fruits have also coveredlarge tracts of the subtropical plains of Punjab, U.P and H.P. For the hills,promising cultivars identified need further spread.

Generally, apple is grown in marginal land and fertilizers are not appliedaccording to the requirements of the trees. The water and fertilizer useefficiency is generally poor. Also, spring frost and hailstorms are adverseweather parameters leading to low productivity. Research results have shownthat through proper orchard management practices (soil and waterconservation and fertilizer application) the fruit yield can be doubled in theexisting orchards. The adoption of improved production technology developed


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by the research system can bring visible and perceptible changes in thetemperate fruit industry in India. Technologies like use of clonal rootstocks,introduction of renewal pruning techniques and micro nutrient applicationshave not been transferred and adopted at a satisfactory level.

Apple scab disease has been the major plant protection problem in applein J&K and H.P, whilst U.P hills are comparatively free from the disease. Applescab forecasting system developed and the chemical control scheduleprescribed have helped in reducing loss due to apple scab to a considerableextent. Apple growers are adopting the prescribed schedule of chemical spraysto control the disease. For checking entries of diseased material in the freeareas of U.P. and North-Eastern Hills, strict quarantine and selection of elitedisease-free mother plants are very essential. Often it is not followed strictly.Some of the virus diseases have also been reported in apple for whichbiological and serological indexing/detection procedures have been developed.Limited quantity of virus-free budwood is also being supplied. Extreme careis now required to be taken to multiply quality planting material (in applealone approximately 2 million plants/year) for establishing new plantations.

Most of the orchardists still sell their crop at flowering to contractors asthere is no well organized marketing system. Transportation in the hills itselfis problematic. Post-harvest management problems originating from poorharvesting (strip picking) and improper packing system (non CFB boxes) andlack of proper pre-cooling and cold storage facilities result in huge (25-30%)loss of fruits. Capacity of the processing sector is also inadequate. Productdiversification, value addition and market infrastructure development wouldrequire very substantial investment. The existing processing units are quiteold and they require modernization for which substantial investment isrequired. CA storage trials have shown good promise. Its extension in largergrowing areas is needed. Technology for storage of apple is now known, as aresult of which apple is now available throughout the year.

DECIDUOUS FRUIT PRODUCT ION IN INDIA

India produces all deciduous fruits including pome fruits (apple and pear)and stone fruits (peach, plum, apricot and cherry) in considerable quantity.These are mainly grown in the North-Western Indian States of Jammu andKashmir, Himachal Pradesh and in Uttar Pradesh hills. The North-EasternHills region, comprising of the States of Arunachal Pradesh, Nagaland,Meghalaya, Manipur and Sikkim also grows some of the deciduous fruits ona limited scale. Due to introduction and adaptation of low chilling cultivarsof crops like peach, plum and pear, they are also now being growncommercially in certain areas of the north Indian plains. Out of all thedeciduous fruits, apple is the most important in terms of production andextent. Apple was introduced into the country by the British in the KulluValley of the Himalayan State of H.P. as far back as 1865, while the coloured


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‘Delicious’ cultivars of apple were introduced to Shimla hills of the sameState in 1917. The apple cultivar ‘Ambri’, is considered to be indigenous toKashmir and had been grown long before Western introductions. Pears andother deciduous fruits were domesticated successfully in the early part of the20th century, although some of them were reported to occur under semi-wildconditions much earlier. Apricot was found growing in the drier pockets ofnorthwestern Himalayas and two apricot varieties, locally known as ‘Halman’and ‘Rakchaikarpo’ are reported to be indigenous to Leh-Laddakh areas ofJ&K State.

Sweet cherry was introduced from Europe before India’s independencein 1947, while commercial cultivars of sour cherry have been brought mainlyfrom USA in more recent years. The European and Japanese plum varietiesare grown both in high and low hill areas. A plum variety ‘Santa Rosa’ reportedto be a hybrid between Japanese and American species predominates (70-80%)plantations in the hills. Low chilling cultivars of peach and nectarine such asFlordasum, Flordared, and Sunred nectarine are successful introductions tothe north-Indian plains. Some local selections of peach (Shan-e-Punjab,Sharbati), plum (Jamuni, Alubhokhara) and sand pear (Patharnakh) are alsocultivated on a commercial scale in subtropical-marginal chilling areas of northIndia.

FRUIT CULT IVAT ION IN INDIA

The exhaustive and comprehensive cultivation of vegetables, flowers andfruits is referred to as horticulture. Horticulture in the country has beenthoroughly involved with the cultivation of fruits in India, besides also layingsimultaneous stress upon vegetables and gardening of rare plants. This verystudy of fruit and vegetable production is an arena, which provides sizeablesubject of enormous scope, if pursued passionately in order to take India togreat heights to cultivating fruits in a strategic manner. Cultivation of fruitsin India and in the international scenario, involves the consolidation of widespectrum of disciplines. As the new technologies and developments havegradually become readily available in the country, the cropping andcultivating systems and production practices have also remained witness tosignificant metamorphoses. Indeed, if dug deep into the fascinating historyof fruit cultivation in the country, it can verily be seen that the Silk Route hadplayed a key role in the ushering of various kinds of these delicious sweetand fleshy things called ‘fruits‘ since pre-Christian era, especially fromcountries like China and Egypt.

Fruit cultivation in India is one such major commercial and businesssector for exporting merchandise and shipping, from which much of theinternational revenue is incurred. Since Independence, the country has beentrying to come to terms with the dazzling prospects of exporting commercialbusiness and the land being essentially agrarian and rural, possesses ample


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scope for lands for cultivation and farming. However, the erstwhile toolsand implements of the Central Indian administration, is being upgraded everyfiscal year, a domain which truly looks towards guaranteed future. Numerouskinds of precepts, rules and practices that were common a few years ago inIndia, may just not be no longer be current. India has been perhaps justlyrenamed as the ‘fruit and vegetable basket of the world‘, a factor that weighsfascinatingly upon the cultivation of fruits in the country. India serving ashome to a supreme variety of fruits and vegetables, holds an exclusive positionin production figures amongst other countries. More than 90 percent of India‘sexports in fresh products travels to west Asia and East European markets.India‘s exports of fresh fruits and vegetables has amplified by 2437.12 crorerupees in the 2007-08 financial year. This amplification list merrily incorporatesthe products like walnut, fresh mangos, fresh grapes and umpteen other freshfruits and vegetables.

Since prehistoric times, India has served as an agriculturally dependantcountry. Hundreds of fruits and vegetable types are grown in all parts of India.For such a thriving business to network itself, the Indian industrial strategyhas been known to have expanded from grassroots level, onto big markets,dealing globally. The cultivated fresh fruit and vegetable reach small scalefruits and vegetables suppliers, they are then sent to local markets as well asfruits and vegetables exporters, who in turn make baskets of shipping of fruits,dealing with international buyers. The last few decades have witnessed thenumber of Indian fruit vegetables suppliers and fruits vegetables exportersrising to an all time high. The total production of fruits and vegetables in theworld is approximately 370 metric ton. India proudly ranks first in the world,with an annual output of 32 metric ton, taking the fruit cultivation of Indiangraph shooting sky-high. While there are almost 180 families of fruits thatare cultivated all over the world, citrus fruits represent approximately 20percent of world‘s total fruit production. Major Indian cultivated fruits consistof mango, banana, citrus fruits, apple, guava, papaya, pineapple and grapes.The fruits are further also processed into various products such as fruit juicesand concentrates, canned fruit, dehydrated fruit, jams and jellies etc.

India with its current production of approximately 32 million metric tonof fruits, accounts for about 8 percent of the world‘s fruit production. Thediverse agro-climatic zones present in the country, makes it possible topractically grow almost all varieties of fresh fruits and vegetables in India.The fruit cultivation and production in India has recorded a growth rate of3.9 percent, whereas the fruit processing sector has grown at approximately20 percent per annum. However, the growth rates have been expansivelyhigher for frozen fruits and vegetables (121%) and dehydrated fruits andvegetables (24 percent). There exist more than 4000 fruit processing units inIndia, with an combined capacity of more than 12 lakh metric ton (less than4 percent of total fruits produced). It is reckoned that approximately 20 percent


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of the production of processed fruits is intended for exports, the rest suppliesto the defence, institutional sectors and household consumption; fruitcultivation in India however depends a lot upon mango and mango-basedproducts, constituting 50 percent of exports.

The fruits and vegetable cultivation and processing industry in India ishighly decentralised in content. A large number of units are in the cottage/home scale and small scale sector, possessing small capacities upto 250 tonnesper annum. But big Indian and multinational companies in the sector possessenormous capacities in the range of 30 tonnes per hour more or less. Sinceliberalisation and pulling out of excise duty on fruit and vegetable products,there has been substantial rise in the growth rate of the industry.

The Indian fruit cultivation, especially mangoes and bananas, are now inhuge demand outside the country. India is a producer of tropical fruits likecoconuts, jackfruits, cashew nuts, pineapples, bananas and oranges. Oftemperate fruits, apples, plums, peaches, almonds, apricots and grapes aregrown in abundance. While Jammu and Kashmir and Himachal Pradesh leadin the fruit production of the temperate region, others are grown in variousparts of peninsular India and Northern Plains. India brings in pots of foreignexchange by exporting cashew nuts too. Part of the raw cashew nuts isimported and treated here, before they are later re-exported. The north easternregion of India holds mammoth horticulture potential. States like ArunachalPradesh, Nagaland, Meghalaya and Manipur have favourable soil and climaticconditions and also have great scope for temperate fruit cultivation in theseparts of India to augment business management. Presently stone fruits likepeach, plum and apricot and pome fruits like apple and pear are grown insmall scale but the future is bright and there is great scope for the expansionof temperate fruit culture.

Fruit cultivation in India has received additional impetus in the formatof various state governments realising their functionary role in boosting cnationwide commerce. As such, the Haryana government has been lendinggrants for setting up orchards under the National Horticulture Mission.Under this plan, a special grant of 9,750 rupees per hectare is provided to thefarmers for cultivation of guava, 15,750 rupees per hectare for mango, 11,250rupees for ber and 18,525 rupees for cheeku. This amount is to be disbursedin three years time, according to sources. Ample investment opportunitiesdoes exist in expanding the export market for fruit cultivation in India. Amodifying acceptance of new products with market development efforts havealso been witnessed since long, given the fact that there exists a goodinternational demand for certain fruits and vegetable products. India produces41 percent of world‘s mangoes, 23 percent bananas, 24 percent cashew nutsand 36 percent green peas. The total export value of the main exporting fruitcrop from India is mango. Exports of mangoes, grapes, mushrooms havestarted going to the United Kingdom, Middle East, Singapore and HongKong.


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Mango, termed as the ‘king of fruits in India‘, accounts for 40 percent ofthe national fruit production almost every year. It occupies 42 percent of thecountry‘s 2205.6 thousand hectares land under fruit cultivation in the Indiansubcontinent. India had exported 54350.80 metric ton of fresh mangoes withthe value of 127.42 crore rupees in 2007-08. The major varieties of mangoesexported include-Dashehri, Alphonso, Kesar, Banganpalli, Kesar, Dusheri,Langra, Chausa, Mallika and. Swarnrekha. The major markets for Indianmangoes comprise U.A.E, Bangladesh, U.K, Saudi Arabia and Nepal. India isverily approximated to account for around 60 percent (9.5 million tonnes) ofthe world‘s mango production of 15.7 million tones. The major cultivationand production areas of this fleshy fruit in Indian subcontinent are in the statesof Andhra Pradesh, Uttar Pradesh, Karnataka, Bihar, Gujarat and Maharashtra.India is one of the leading exporters of fresh table grapes to the global market;India‘s export of grapes has increased from 301.92 crore rupees in 2006-07 to317.83 crore rupees in 2007-08. The leading destinations for export of Indiancomprise Netherlands, U.K, U.A.E, Bangladesh and Belgium.

As has already been stated that the country is the largest producer offruits in the world, acknowledging it as the fruit basket of world, India‘s fruitcultivation has been orchestrated after several application of masterminds tohave thus reached such a position. The major fruits cultivated in India aremangos, grapes, apple, apricots, orange, banana, avocados, guava, lichi,papaya, sapota and water melons. This is due to its potential in different agroclimatic zones. India‘s export of fresh fruits to the major countries consists ofU.K, Netherlands, U.A.E, Russia, Bahrain, Qatar, Kuwait, Saudi Arabia,Bangladesh and Nepal.

Fruit cultivation in India further has always remained a recipient of hugerespect and admiration, owing to its marvellous produces of deciduous fruits,including pome fruits (apple and pear) and stone fruits (peach, plum, apricotand cherry) in considerable quantities. Deciduous fruits and its cultivation inIndia mainly takes place in the north Indian states of Jammu and Kashmir,Himachal Pradesh and in the Uttar Pradesh hills. The northeastern hillsregion, comprising the states of Arunachal Pradesh, Nagaland, Meghalaya,Manipur and Sikkim, also grow some of the deciduous fruits on a restrictedscale. Due to initiation and adaptation of low chilling cultivars of crops likepeach, plum and pear, they are also presently being grown commercially incertain areas of the north Indian plains too. Out of all the deciduous fruits,apple is the most vital in terms of production and extent.

From amongst the umpteen and healthy and palatable deciduous fruitcultivation in India, apple demands and calls for incredible attention. Indeed,apple was introduced into the country by the British Raj in the Kullu Valleyof the Himalayan state of Himachal Pradesh as far back as 1865. On the otherhand, the coloured ‘delicious‘ cultivars of apple were introduced to the Shimla


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hills of the same state in 1917. The apple cultivar Ambri, is measured asindigenous to Kashmir and had been grown long before Westernintroductions. Pears and other deciduous fruits were domesticated lucrativelyduring the early part of the 20th century, although some of them wereaccounted to occur under semi-wild conditions much earlier. Apricot wasfound growing in the drier pockets of northwestern Himalayas and two apricotvarieties, locally acknowledged as Halman and Rakchaikarpo, are reportedto be indigenous to the Leh-Ladakh region Jammu and Kashmir state.

Sweet cherry was introduced from Europe before India‘s independencein 1947, whereas, commercial cultivars of sour cherry have been fetchedprimarily from USA in more recent years. The European and Japanese plumkinds are cultivated both in high and low hill areas. A plum variety ‘SantaRosa‘, reported to be a hybrid between Japanese and American species,predominates (70-80 percent) plantations in the Himalayan hills. Low chillingcultivars of peach and nectarine such as Flordasum, Flordared, and Sunrednectarine are booming introductions to the north-Indian plains. Some localselections of peach, plum and sand pear (Patharnakh) have also taken fruitcultivation in India on a grand commercial scale in subtropical marginalchilling areas of north India. Fruit cultivation in India, quite understandablygrows most prolific in the areas of the Himalayas, with abundance speakingout from every angle. The Uttar Pradesh hills, particularly the Kumaon hillsdivision, possesses exceptional advantage of early harvest of apple, principallydue to cultivation of early maturing varieties like Early Shanburry, Fannyand Benoni. The early maturing varieties are harvested 2-3 weeks before theonset of fresh apple from Himachal Pradesh and Jammu and Kashmir andhence, fetch very moneymaking prices. Deciduous fruits, covering pome andstone fruits contribute significantly to the horticulture economy of India. Truly,cultivation of fruits in India, does depend upon the success of plantation,harvest, soils and a perfect ambience of brilliant minds.


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5

Tropical Fruit Crops

A large number of tropical and subtropical fruit crop species have highlyrecalcitrant seeds often exhibiting viability of just a few weeks. Severalvegetatively propagated tropical fruits including woody perennials need tobe conserved with their genetic fidelity intact. Maintenance and preservationof germplasm of fruits in field genebanks is difficult, expensive and labour-intensive. Besides, the conection may also be vulnerable to naturalperturbations.

Although conservation of seeds of economically important crops has beenpractised since times immemorial, it suffers from severe limitations like lowseed viability and heterozygosity. Therefore, a need was felt to developalternative methods, viz., in vitro preservation. New techniques help toconserve germplasm disease-free, but also involve lower labour costs andrequirement for technical personnel besides limiting disease-transfer (Withersand Engelmann 1990).

TROPICAL FRUIT GERMPLASM

A considerable variety of tropical fruits are grown in Asia, in particularin South and South-East Asia. The region is a centre of diversity for severalimportant native fruits which include mango (Mangifera indica), Citrus andrambutan (Nephelium lappaceum) (Arora 1994; Kajiura 1990). In addition,more than 200 minor, underutilized native species occur; these are collectedin the wild or grown in home gardens. Some of these species have considerablepotential, such as breadfruit (Artocarpus altilis) and jackfruit (Artocarpusheterophyllus), which are rich in carbohydrates, proteins, minerals and manyvitamins. Examples of minor fruit crops with high genetic variation in theregion are carambola (Averrhoa carambola), longan (Dimocarpus longan) andaonla (Phyllanthus emblica).

Just as for other crops, it is important to conserve the genetic material ofthe various fruits. Human beings are highly dependent on plants for survival.Plants are mainly used for food, but also as sources for building material,

fibres, medicines, oils, rubber, perfumes and dyes. The relationships betweenhuman being and plants are not static. Because of constantly changing needsin human nutrition, increasing population and industrialisation and trade, alarge variety of species is required to meet these needs.

In India and its neighbouring countries, various native fruits, such asaonla, beal fruit (Aegle marmelos), jackfruit, jamun (Syzygium cuminii),karonda (Carissa congesta), Kokum (Garcinia indica) and phalsa (Grewiasubinaequalis) are underutilized. Some of these might be important in thenear or far future, because of their therapeutic/medicinal and nutritive valueas well as their excellent flavour and very attractive appearance. Consumerstoday are becoming increasingly conscious of the health and nutritional aspectsof their food.

Underutilized fruits could play an important role in satisfying demandfor nutritious, pleasantly flavoured and attractive natural food of hightherapeutic value. Encouraging local people to produce these fruits can helpto improve their social and economic welfare. In this way, they can alsosignificantly contribute to the preservation of the environment by stoppinguncontrolled harvesting from the wild and assisting in the retention of thevarious species in their native habitats where they perform best.

Conservation is very important, because many species are becomingextinct and many others are threatened and endangered. The diversity of somefruits is well collected, while for other fruits relatively little has been doneyet. Gaps in collections are found both between species and between regions.This is especially true for both underutilized species and wild crop relatives,where big gaps are noted. Kostermans and Bompard (1993) indicate thatMangifera blommesteinii, M. leschenaultii, M. superba and M. paludosa arein real danger of extinction. High genetic erosion has been noted for jackfruit,Citrus sp. and Litchi chinensis in a survey carried out by the InternationalCentre for Underutilized Crops (ICUC) and IPGRI.

Furthermore, great genetic diversity is required in order to have a stableecosystem. In the case of species, which are already used by human beings ascrops, it is very important to have a broad genetic base, to improve existinggenotypes when necessary. Finally, the diversity of plants in differentecosystems brings a lot of pleasure and inspiration to people with culturaland/or religious significance and the potential for income generation througheco-tourism. Thus, it is important to appreciate the contribution to humanwelfare and environmental sustainability made by all the three levels ofbiodiversity: (i) ecosystems, (ii) species, and (iii) genetic diversity.

This chapter deals with in situ conservation, particularly as it relates totropical fruit crops. Two different approaches of in situ conservation aredistinguished, namely, genetic reserves and on-farm conservation. Beforegoing into detail on both approaches, major problems and constraints for insitu conservation research are reviewed to give a better understanding on


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the status of in situ conservation at present. Lastly, various examples, a fewon tropical fruits, are presented on how in situ conservation could be applied.These examples can provide a basis for further discussion on how to approachand apply in situ conservation.

DEFINIT IONS

In situ conservation is defined as the conservation of ecosystems andnatural habitats, and the maintenance and recovery of viable populations ofspecies in their natural surroundings and, in the case of domesticated orcultivated species, in the surroundings where they have developed theirdistinctive properties.

Ex situ conservation, on the other hand, is defined as the conservation ofcomponents of biological diversity outside their natural habitats, for example,in genebanks (CBFD 1992). Thus, conserved species can be either wild ordomesticated and habitats can be either natural ecosystems or agro-ecosystems. In practice, the situation is more complex as different intermediatetypes exist. For example, IPGRI divides its mandate crops into the followinggroups: cultivated species and their wild relatives and useful forestry species.Brush (1991) distinguishes the following four categories of crop germplasm:wild crop relatives, semi-domesticated (weedy) crop relatives, perennialspecies and landraces of ancestral crop species.

In this chapter, the in situ conservation strategy is divided into twogeneral approaches, following the working definitions proposed by Maxtedet al. (1997).

1. Genetic Reserve Conservation: The location, management andmonitoring of genetic diversity in natural wild populations withindefined areas designated for active, long-term conservation.

2. On-farm Conservation: The sustainable management of geneticdiversity of locally developed traditional crop varieties withassociated wild and weedy species or forms by farmers withintraditional agricultural, horticultural or agri-silvicultural cultivationsystems.

In Situ Conservation

Traditional, many crops are conserved as seed in genebanks. However,conservation of tropical fruit crops often takes place in field genebanks dueto the recalcitrant nature of the seeds of many of them. Major disadvantagesof field genebanks, such as high maintenance costs, the limited amount ofgenetic variation that can be stored and vulnerability to natural and humandisasters have led to efforts to develop in vitro conservation methods.

This conservation can be either under slow growth conditions or throughcryopreservation (preservation at very low temperatures in liquid nitrogen).Pollen and DNA conservation are two other techniques, which are being


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explored and are used on a small scale. All of the above mentioned ex situconservation techniques have their niche in conserving part of the geneticvariation of fruits. However, the conservation of plant material outside itsnatural habitat brings disadvantages. For example, to conserve material exsitu, it is necessary to remove it from the area in which the plants occurnaturally, so interrupting the evolutionary process. Risk of genetic driftincreases. This disadvantage can be resolved by using an in situ conservationstrategy. However, this does not mean that in situ conservation is the only orbest way of conservation; rather it should be seen and used as an additionaland complementary technique. In situ conservation can be a valuable tool,because it extends the conservation of a species beyond the level of theindividual to the habitat or ecosystem in which the species lives.

In addition to preserving the plant material per se, the processes thatcreate new genotypes are also conserved. In other words, evolutionaryprocesses continue letting the plant populations continually adapt to thechanging environment. Furthermore, in many case's, it is easier to conserve aviable population in situ than ex situ. This is certainly true of tree species. Insitu conservation might be of great importance for: (i) recalcitrant seededspecies, (ii) wild relatives, (iii) wild species, and (iv) species depending onother organisms within the ecosystem, e.g., some plant species have highlyspecialised breeding systems, which require insect or birds for pollination.For the first group, other solutions which are often very expensive, might resultin the conservation of a limited number of accessions. The second and certainlythe third group often receive a low priority in collecting, which could beresolved by in situ conservation. For the last group in situ conservation is theonly way.

Major Problems and Constraints for in Situ Conservation

At present, there is substantial body of information available on thedevelopment and establishment of biological reserves. However, there islimited information on the development and establishment of genetic reservesand only very limited knowledge is available on on-farm conservation.Knowledge on the genetic diversity of the target species, agro-ecology andindigenous knowledge are recognised as important elements for on-farmconservation, yet a logical framework is lacking. Iwanaga (1995) recognisedand distinguished the following problems and constraints for in situconservation of crops, their wild relatives, and useful forest and non-forestplant species:

• The absence of a formal institutional framework able to developand support in situ conservation activities.

• Lack of linkages (both formal and informal) between differentgroups interested in maintaining or conserving different species andtypes of plant germplasm in situ.


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• Inadequate knowledge of communities who maintain crop or otherplant germplasm in situ and an absence of systems for supportingsuch communities (and frequently, a lack of recognition of theirrole and interests).

• Low level of awareness by formal-sector agencies of the significanceof in situ conservation and the contribution that it can make tobiodiversity maintenance and to provision of useful germplasm asa contribution to development.

• Limited number of trained personnel able to guide and lead thedevelopment of in situ conservation activities of crop, forestry andother plant species.

• Major limitations in the knowledge base with respect to selectionof in situ conservation locations, their monitoring and management.

• A lack of effective analysis of the relationship between developmentand conservation of the different forms this relationship can takeand the impact these will have on the maintenance of the diversity.In the next part of this presentation, existing approaches andframeworks for in situ conservation are described. However, beforethat, different activities that should be undertaken in order to beable to develop and establish final conservation plan are presented.

Preliminary Information Gathering for in Situ Conservation

Before planning and designing a genetic reserve or an on-farmconservation project, several issues need to be considered. Firstly, the maintarget and related species should be identified. The choice for these shouldbe objective, based on logical, scientific and economic principles related tovalue and use of the species. Other important factors influencing the choiceof a target are threats, which vary from species to species. These threats canbe grouped under the headings of overexploitation, habitat destruction orfragmentation, competition from introductions, changes and intensificationof land use, environmental pollution and climatic change (Maxted and Hawkes1997).

A practical approach to select target species could be the use of thegenepool concept of Harlan and de Wet (1971). This concept is based on theease with which species hybridize with each other. Three categories ofgenepools are proposed:

• Primary Genepool (GP-1): This includes the true biological speciesincluding all cultivated, wild and weedy forms. Crossing betweenthe various species within this genepool should not cause anyproblems and the derived hybrids should generally be fertile.

• Secondary Genepool (GP-2): This includes those biological species thatcan be hybridized with the main species, but often result in sterileprogeny.


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• Tertiary Genepool (GP-3): This includes the species that only couldbe hybridized with the main species with difficulty, e.g., use ofembryo culture, doubling the chromosome number or usingbridging species. Resulting hybrids are anomalous, lethal and/orsterile.

The availability of information on different genepools enables the prioritysetting of target species to be incorporated into the in situ conservationstrategy. The general importance of a species and the number selected withina species depends on the ease with which they can be used. So this meansthat the highest priority should generally go to species in the primary genepooland the lowest to those species in the tertiary genepool. In formulatingstrategies for the conservation of any crop, it is essential to know its areas ofdistribution, and to understand the diversity and location of its wild relatives.This knowledge base should consist of both geographical and ecologicalinformation. Furthermore, information on the density of the different speciesis needed.

In order to conserve biological diversity, conservation programmes mustbe guided by the biology of the species or systems that one seeks to preserve.The taxonomic status, geographical range, life form, breeding system and seeddispersal mechanism all have significant effects on the levels of geneticdiversity maintained by a species (Hamrick et al. 1991). These factors influencethe genetic diversity within and between populations of the target species.

Dicots generally have a lower genetic diversity than monocots andgymnosperms. Annuals and short-lived perennials and endemic speciesnormally have a lower genetic diversity than long-lived perennials and widespread species. Higher diversity is found among cross pollinating species thanin self-pollinating species.

The foregoing information indicates that species with limited potentialfor gene flow have more differentiation between populations, while specieswith a high potential for gene flow have more differentiation within thepopulation. Gene flow potential is closely correlated with type of pollination,seed dispersal mechanisms, longevity and seed size. Hamrick et al. (1991)concluded that species with high levels of genetic diversity are more likely tohave populations with high genetic diversity than those species with low levelsof genetic diversity.

In addition to the various technical aspects influencing the choice of targetspecies, and location and size of genetic reserves, socioeconomic and politicalfactors also play a role. Firstly, there are various international agreements andconventions influencing and impacting upon the conservation of plant geneticresources, among which more important are the following:

• The Convention on Biological Diversity (CBD).• Agenda 21.• Resolution 5/89 on Farmers Rights.


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• FAO Global Plan of Action for the Conservation and SustainableUtilization of Plant Genetic Resources for Food and Agriculture.

Article 8 of the CBD, a legally binding convention, accepted by theConference for the Adopting of the Agreed Text of the Convention onBiological Diversity met at UNEP Headquarters in Nairobi, Kenya in 1992,deals with in situ conservation. Although this is a fairly long article, it can besummarised as follows: the contracting parties should establish a system ofprotected areas to conserve biological diversity. This should be done in sucha way that conservation is ensured and that diversity will be used in asustainable way. Guidelines for the selection, establishment and managementof protected areas should be developed where necessary. These legally bindingnorms provide a broad basis for both genetic reserves and on-farmconservation.

In situ conservation is also discussed in Chapter 14.G of Agenda 21. Twomajor objectives of this programme are:

1. to adopt policies and strengthen or establish programmes for insitu conservation.

2. to take care of sustainable use of plant genetic resources for foodand agriculture, integrated into strategies and programmes forsustainable agriculture.

3. to take appropriate measures for the fair and equitable sharing ofbenefits and development in plant breeding between the sourcesand users of PGR".

Resolution 5/89 on Farmers Rights was added in 1989 to The InternationalUndertaking on Plant Genetic Resources. Resolution on Farmers Rights aimsto :

1. ensure that full benefit to farmers from the exploitation of thediversity that farmers have generated goes to the farmersthemselves.

2. support the continuation of the contributions by farmers to thedevelopment and maintenance of landraces.

3. attain the purpose of the undertaking. The purpose of theundertaking according to Art. 1 is to ensure that "plant geneticresources, especially species of present or future economic and socialimportance, are explored, collected, conserved, evaluated, utilizedand made available, for plant breeding and other scientificpurposes."

Farmers Rights differ from plant breeders right (PBR), in that the objectiveof Farmers Rights is the conservation and sustainable use of biologicalresources to serve the community, rather than allowing that biologicalresources to become a commodity. Furthermore, these rights are a counterpartto intellectual property rights (IPR). In addition to establishing funds tosupport farmers in protecting and conserving genetic diversity and to inform


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the public about the importance of conserving these genetic resources, it alsoguarantees full benefit to farmers of the gains which are realised by othersusing the plant genetic resources developed by farmers.

The GPA is a set of recommendations and activities arising from theReport on the State of the World's Plant Genetic Resources, prepared in 1996on the basis of 150 country reports. The GPA was adopted at the FAOInternational Technical Conference on Plant Genetic Resources held in Leipzig,Germany in June 1996.

The GPA main objectives are to:• ensure the conservation of PGRFA as the basis of food security.• promote sustainable use of PGR to foster development and reduce

hunger and poverty.• promote the fair and equitable sharing of the benefits arising from

the use of PGR.• assist countries and institutions to identify priorities for action.• strengthen existing programmes and enhance institutional capacity.The GPA refers to both in situ and ex situ conservation. For in situ

conservation, four main activities are recommended in this book of the GPA.Firstly, PGRFA should be surveyed and inventoried, in order to be able todevelop rational conservation systems and national policies for the use of theseresources. Secondly, more support through training, participatory researchand a supporting policy environment will be provided for the managementand improvement of on-farm conservation.

Thirdly, assistance will be offered to farmers in disaster situations, suchas war, civil strife or natural disasters to restore agricultural systems. Lastly,the in situ conservation of wild crop relatives and wild plants for foodproduction will be promoted through improved management of the geneticresources in genetic reserves.

National policies should deal with the national agricultural policy, thenational research agenda, genetic conservation programmes, farmerconsultation by official agencies, education and incentives for farmers andfarming resources (Henne 1995). The 1992 National Integrated Protected AreasSystem Law of the Philippines is an example in which the legal instrumentspecifically addresses genetic conservation management.

One of the problems which can be encountered here is that such lawscan actually cut across the mandated areas of responsibility of a number ofdifferent ministries and departments, such as agriculture and environmentalaffairs. This makes the application and enforcement of these laws very difficult.

Lastly, it is extremely important to get local communities involved,because they are socially and economically dependent on the environmentwhere the conservation should take place, especially for on-farm conservation.However, even in the case of natural reserves, local communities are oftendependent on those areas for example for the collection of food, medicinal


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plants and fuel wood. The collected material can be either for own use orcash income.

Thus, it is important to explain the purpose of in situ conservation tolocal communities, to obtain information from them on the area, and toexchange ideas about the selection of a site, using rapid appraisal andparticipatory appraisal techniques. In other words, indigenous knowledgeshould be considered as a valuable source of information. Finally, it is veryimportant that communities feel and take responsibility for the entire project.This can make the difference between success and disaster.

Genetic Reserves

A model for how to plan and establish a genetic reserve has beendeveloped by Maxted et al. (1997). This model divides the entire process ofestablishment and use of genetic reserve into three phases:

1. Reserve planning and establishment.2. Reserve management and monitoring.3. Reserve utilisation.

Reserve Planning and Establishment

Using ecogeographic studies, broad areas of genetic diversity areidentified. For the establishment of the actual reserve, precise sites have to bedefined within these broad areas. Potential sites require a detailed surveybased on taxonomic diversity of target species in order to have detailed andup-to-date information on the various sites to facilitate the selection of bestsites. This assessment of genetic diversity increasingly involves the use ofmolecular techniques, such as isozymes or DNA markers. Furthermore, thehabitat requirements of the target taxa should be verified and the most suitablesites should contain robust populations of the target taxa.

The sites should hold as much genetic diversity as possible, because theminimum viable population size is often not determined in advance ofconservation (Maxted et al. 1997). To prevent total loss of a target species, it isadvisable to establish more than one reserve, selecting sites which complementeach other. This means that the widest possible range of different ecologicaland geographic zones in which the target species are found, should be covered.

When considering potential sites for establishing genetic reserves, itwould be advantageous to link these to other ongoing conservation interests.In the wider conservation movement, the types of protected area are fairlywell understood as defined by the IUCN Commission on National Parks andProtected Areas, and also by various international networks and conventions.As far as possible, genetic reserves should be designed within the generalframework set out by these agreements.

Some sort of cost-benefit analysis should be carried out for each site inorder to be able to select the most valuable one. It is not easy to measure the


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benefits, as it is very difficult to estimate the value of a resource especiallywhen it is not of particular interest at this moment, but which might have avalue in future. This often means that these figures cannot have more thanmoral and scientific value. The relative costs of establishing a reserve alsoaffect selection of the site. Obviously, if two sites are of equal genetic value,the one which will be the cheapest to establish should be selected. Due toproblems in estimating benefits, the cost-benefit analysis cannot be decisivefor the site selection; rather it is an additional information source.

Subsequently, the reserve site should be sustainable in this role forforeseeable future. It must be accessible to the reserve manager and potentialusers. When selecting a site, the national regulations and policy on plantgenetic resources should be kept in mind. It is very important to involve thelocal community and this should be done at as early a stage as possible.

After the site for a reserve is determined, the reserve itself should bedesigned. Factors, such as structure, size, whether a single large or multiplesmaller sites for the target species, the use of corridors, reserve shape,environmental heterogeneity and potential user communities have to beconsidered (Maxted et al. 1997).

According to the Man and the Biosphere Programme (UNESCO), a geneticreserve should consist of a core zone surrounded by a buffer zone and outsidethat, if possible, a transition zone. The core zone should represent a naturalundisturbed or minimally disturbed area, representative of the ecosystem.Certain degree of management need to take place and the core species needto be monitored. The buffer zone protects the core zone from edge effects andother factors that might threaten the viability of the target populations in thecore. It also allows the reserve to have a more natural boundary. In addition,the buffer zone allows restricted use of the traditionally utilized species bythe local communities and it can be used for research, education,demonstration and harmonious interaction with people. The transition zoneserves to shield the core zone from general areas of human exploitation.

This zone may be used for the development and research of propertechniques for eco-restoration, limited human settlement, sustainableutilisation and tourism (Hawkes et al. 1997). The size of a genetic reserveshould be large enough to ensure self-perpetuation and continuing evolutionof the biodiversity within it (Arora and Paroda 1991). This means that thecore zone should contain at least 1000 to 5000 potentially breeding individualsto represent a population, the minimum viable population size (Hawkes et al.1997).

The reserve design can be based either on the use of various small reservesor on one large reserve. For example, is it better to have one large reserve of15 000 hectares or a network of five, each of 3000 hectares? A large reservehas as advantage that it might cover more habitat types than small reserves.However, the different small reserves can be placed in different environment


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to enable conserve all extreme ecotypes. Of course, it should be kept in mindthat small reserves should be big enough to contain the minimal populationsize to survive.

The size and number of reserves depend on the characteristics of the targetpopulation. Large areas are better for maintaining larger species, while smallermultiple reserves might be appropriate for annual plant species that are oftenfound in dense but restricted stands (Maxted et al. 1997). For the majority ofthe wild relatives of crop plants, the establishment of multiple small reservesis preferred, because they are generally widely distributed over a range ofdifferent ecosystems. The conservation value of multiple small reserves canbe increased by the establishment of corridors which facilitate gene flow andmigration between the component reserves.

The edge of a reserve should be kept to a minimum to avoid side effectsfrom the outer environment, such as changes in light, temperature, wind, theincidence of fire, introduction of alien species, grazing and deleteriousanthropogenic effects. For that reason, a round-shaped reserve has the lowestedge to area ratio. It should also be realised that each disturbance in thereserve, such as roads, dams and fences causes additional edge effects (Maxtedet al. 1997).

Lastly, the sustainability of the reserve needs to be considered. Incomparison with the maintenance costs of ex situ conservation, themaintenance costs for reserves are high. This is due to the need for active andconsistent population monitoring, habitat management and site security, allof which require the commitment of substantial level of resources for asubstantial period of time. If material is lost during the in situ conservationprocess, it could be reintroduced, if stored at another place, either in anotherreserve or ex situ.

It is also important for sustainability to obtain as much knowledge aspossible about future plans for human development for the site selected.Legislation ensuring that once a reserve has been established, it is maintainedto assist in securing the sustainability of the reserve (Maxted et al. 1997).

Reserve Management and Monitoring

To be able to manage a reserve in a proper way, a good managementplan has to be established. Management plans normally contain informationon conservation objectives, site biotic and abiotic dynamics, site history, publicinterest, factors influencing management, management prescription (whatwork needs to be carried out and precisely how and when to do it), ecologicaland genetic survey and monitoring schedule, budget and human resources(Maxted et al. 1997).

In the case of the conservation of certain target species in a reserve,information should be added on the species themselves. This informationshould be both general (taxonomy, phenology, habitat preference, breeding


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system and minimum population size), and specific, based on the site (mappingof populations, information on density within the site and interaction ofspecies with the surrounding environment). Furthermore, the plan shouldcontain information on what is an acceptable fluctuation in size of thepopulations (maximum and minimum values) and when to raise the alarmto take alternative actions to save populations.

A good management plan should also contain detailed information onthe appropriate level of intervention through grazing, mowing, burning,planting and harvesting regimes (Maxted et al. 1997). When the managementplan is introduced, it should be continuously combined with evaluation,revision and refinement in the light of its practical application. An exampleof how management can influence a population is seen in the cutting or non-cutting of branches of Myrica trees in Japan. In the protected forest zone alongthe coastal cliff at Yahatano Village at the Izu Peninsula, large Myrica treesform a part of the upper forest canopy, but young trees are not found insidethe forest. On the other hand, in the inland zone forest, where managementhas been practised to obtain evergreen and deciduous coppice forests, youngtrees are found at high frequency. This suggest that the availability of morelight through cutting has made invasion and growth of Myrica trees possible.

To be able to follow how a population develops over time, it should bemonitored regularly. The following activities are part of the monitoringprocess: defining objectives, identifying key associated taxa and samplequadrat locations, selection of data for quadrat recording, determination ofdesirable frequency and timing of quadrat recording, accumulation of datasets, statistical analysis and production of recommendations on themanagement plan (Maxted et al. 1997).

Since it is impossible to record and monitor all species or individualplants, samples are taken and key indicator taxa, mostly including the targetspecies, and key indicator sites are measured. This involves the use of bothfixed and random quadrats or transects within the reserve. There are severalmethods to measure the abundance or diversity within quadrats or transects.The most commonly used is presence or absence with an estimate of densitywhen present. Absolute numbers could also be taken, but that is more timeconsuming. There is no recommended size for quadrats, but it is the best tokeep the same size for all quadrats at every location and time. Furthermore,monitoring should take place in the same season to facilitate comparisons fromyear to year.

Reserve Utilization

Genetic reserves are not just established for conservation on itself, but toconserve PGR which might go extinct and be needed in the near or distantfuture. The conserved material is or could be utilized by different groups andfor different reasons. Three different groups of users are recognised:


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1. local communities.2. general public.3. scientific professionals.The establishment of a reserve will often disrupt the normal activities

carried out by local people, such as collecting, hunting or simply visiting thearea. To work in the reserve in a sustainable manner, the support of the localcommunity for conservation should be obtained.

To avoid disruption to the activities of local communities, whereverpossible, sustainable use of the buffer and transition zones by local traditionalcommunities should be encouraged. The second user group is the generalpublic, who pay for the reserves by taxation. So it is very important to havethe support of the general public and make them aware of the importance ofconservation. Both ethical and aesthetic reasons are often very well accepted.In addition, the reserves could be used by the general public for example foreducation and eco-tourism.

The scientific professionals will utilize the conserved material in the sameway as material that is conserved ex situ. A disadvantage of the in situapproach might be that the material is not easily accessible for the plantbreeder, this can be avoided by characterizing much of the material anddisseminate the collated information. The seasonality of the reserve mightalso limit the access of the reserve, because fruits and seeds can only becollected during the fruiting season of the species. An advantage of in situgenetic reserves for the professionals is that evolutionary studies of the targetspecies can be carried out.

Examples of Genetic Reserves

Myrica rubra is dioecious with its female tree bearing reddish to purplefruits as well as a dye from its bark. It is distributed in coastal areas fromsouthern China to central Japan. Fruit of M. rubra is consumed fresh or brewedinto wine or reddish liquor. Ukiyamma, a forest located on a flat lava terraceon the Izu Peninsula in Japan is used as a genetic reserve for M. rubra. In the19th century, the management of this forest was directly controlled by theSamurai government. Harvesting of the mature fruits of M. rubra in the forestwas permitted only for inhabitants. If anyone cut a trunk or even a shoot, thedeath penalty by decapitation was imposed because M. rubra was animportant economic crop at that time. Since then, M. rubra trees have beenpreserved as common property by means of an agreement by the villagers.

Kostermans and Bompard (1993) recommended that conservation ofMangifera species should be both ex situ and in situ. Although in situconservation has advantages, since the trees remain in their natural habitat,its big drawback is that the nature reserves in Asia, especially in Indonesia,are not secure. From this example, it is clear that further investigations areneeded to explore if in situ conservation is possible or not.


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In 1993, a pioneering project on in, situ conservation of wild croprelatives and important forest trees species was started in Turkey. This projectaims to provide a national strategy and action plan for the conservation ofwild relatives through the development of in situ conservation areas (calledmanagement zones) where populations of the most important wild relativesoccur. It involves ecogeographic surveys, selection of the sites, developmentof management plans, and activities to maintain the selected populations,creation of an effective national plan and capacity to carry out the plannedprogramme on a sustained basis.

At the moment, seven 'Biosphere reserves' have been established in Indiaby the Department of Environment and Forests to preserve biodiversity. Thereare plans underway for the establishment of another seven. These reserveshave been chosen, because they all have a high genetic diversity and alsobecause they represent ecosystems in the different biogeographic regions ofthe country.

In relation to tropical fruits, it would be more important to haveinformation on the biodiversity held within the core areas of a reserve. Untildetailed surveys are carried out in the biosphere reserves, it is rather difficultto have exact information on the diversity of fruit crops. The only informationavailable can be found in the synthesis published by the National Bureau ofPlant Genetic Resources (NBPGR) in India (Arora and Paroda 1991).

In the Western Ghats, where the biosphere reserve of Nilgiri Hills islocated, jackfruit and mango are known to be distributed. Furthermore, speciesof Syzygium are found in the Eastern Ghats, where the Gulf of Mannarbiosphere reserve is located. Lastly, various Citrus species are found in thenortheastern region where the Manas biosphere reserve is located and theNamdapha and Kaziranga biosphere reserves are to be established. Eventhough information is collected on the presence of fruit crops, no data areavailable on the density and diversity of each species.

On-farm Conservation

As defined earlier, on-farm conservation of PGR is concerned with crops,and their weedy and wild relatives. On-farm conservation is dynamic and isaimed at maintaining the evolutionary processes that continue to shape geneticdiversity. It is based on the recognition that farmers have improved and growngenetic diversity and that this process still continues among many farmers inspite of socio-economic and technical changes.

Farmers play a big role through their selection of plant material whichinfluences the evolutionary process and through their decisions to continuewith a certain landrace or not.

Landraces are part of agricultural systems. Therefore, on-site conservationcannot be achieved through their isolation in biological reserves. Accordingto Brush (1991) and Bellon (1995), farmers should be encouraged to continue


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planting their landraces and thereby conserve them. This implies a radicallydifferent approach to conservation, one in which farmers play a role equallyimportant as that of scientists and politicians. There have been only a fewstudies aimed at studying on-farm conservation and up to now, no modelexists for the development and establishment of on-farm conservation. If on-farm conservation is to be implemented, a fuller understanding of both croppopulations on the farming systems that produce them is needed to createactive cooperation between farmers and conservationists. Bellon (1995) arguesthat the focus of on-farm conservation should not only be on the varieties afarmer grows, but also on seed flows, variety selection, variety adaptationand seed selection and storage. All elements of the farmers' managementinfluence the whole process of on-farm conservation and these should bestudied.

Since scientific back-up for on-farm conservation is lacking, Brush (1991)suggests five general guiding principles that may be used in evaluatingproposals and pilot on-farm conservation programmes:

1. Even while focusing on on-farm conservation, it is important to beaware of the complementarity of the different techniques. Ex situconservation be used as a back-up in case material is lost in situ.

2. Institutional development of in situ conservation strategies shouldbe related to the activities already found in. farming system.

3. The existing institutions and incentives should be reinforced ratherthan create new ones to provide continuity.

4. Conservation by farmers can be strengthened by agriculturaldevelopment policies that enhance incentives to continue tomaintain landraces. Given the role of farmers in on-farmconservation, meeting development goals such as increased farmincome, is critical.

5. Crop germplasm is an international public good and its conservationmust be supported through international means.

According to Brush (1991), the main challenge in implementing in situconservation for crop species is to encourage farmers to continue cultivationof the various landraces. Therefore, he suggests that an institutionalframework, an extensive information base and a policy framework arerequired to develop and establish an on-farm reserve.

IPGRI, based on a number of Brush's recommendations, has developed aglobal project entitled "Strengthening the Scientific Basis of in SituConservation of Agricultural Biodiversity". The project consists of case studiesin 9 countries including Nepal and Vietnam. The objectives of this projectare to:

1. Enhance and support a framework of knowledge on farmer decisionmaking processes that influence in situ conservation of agriculturalcrop diversity.


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2. Strengthen national institutions in planning and implementationof conservation programmes for agricultural biodiversity.

3. Broaden the use of agricultural biodiversity and to involve farmingcommunities in its conservation.

As a first step, a basic data set will be collected through interviews onfarmer decision making in the selection and maintenance of landraces toprovide measurable indices of genetic diversity of the landraces. In addition,morphological and agricultural information relating to characteristics that thefarmer does not actively select for are also being gathered. Finally, biochemicaland molecular markers will be used. Once a basic data set is established, keyfactors that affect farmer decision making will be identified. A wide range ofenvironmental biological, socioeconomic and/or cultural factors will beincluded. To obtain all the information described above, IPGRI collaboratesclosely with national programmes. To support national capacity building,IPGRI will also provide training on in situ conservation in the fields ofconservation biology, populations genetics, ecology, etc.

FUNGAL DISEASES IN TROPICAL FRUITS

M ANGO

Mango (Mangifera indica L.) is an important fruit and is subjected to anumber of diseases at all stages of its development i.e. from nursery to theconsumption of fruits. All the plant parts, namely, trunk, branch, twig, leaf,petiole, flower and fruit are attacked by different pathogens. Some of thediseases are very severe on plant and produce alike and have become alimiting factor in profitable mango orcharding. Bloom blight caused a completefailure of the crop in Florida and Brazil, black spot in South Africa andpowdery mildew and Black-tip in India, etc. Many types of agents causediseases in mango and of these fungi cause the largest number of diseases,while bacteria, algae, angiospermic parasites and nutritional deficiencies arethe other causal agents of mango maladies. Virus, which causes severeinfection in other fruit crops, is luckily not reported so far on mango.

Many of the mango diseases have been investigated and also measuresto combat them have been worked out in different countries. However, ourknowledge about them is still imperfect and inadequate. Vast areas in South-East Asia - the home of mango, still remain unexplored from disease point ofview and may possibly offer many other problems for investigations. Theinformation available on some of the important diseases.

Powdery Mildew (Oidium Mangifera Bert.)

First reported from Brazil in 1914 by Berthet, later on it has been recordedfrom several countries of the world. In India, it has been reported from Uttar


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Pradesh, Punjab, Maharashtra, Gujarat, Madhya Pradesh, Jammu & Kashmir,Haryana, Andhra Pradesh, Karnataka and Tamil Nadu. The losses caused varyfrom 5-20 per cent depending upon the weather conditions. Prakash andSrivastava (1987) reported 30-90% losses in Lucknow. This is a serious problemin hills, valleys and tarai regions of Uttar Pradesh. Serious outbreaks havebeen noticed in Uttar Pradesh in the last 6-7 years. It attacks the leaves, flowerscales, buds of tender flower heads, axils, stalks and fruits. It manifests itselfas wefts of white mycelium on the affected parts.

The whole surface is later on covered with a powdery substance whichis blown away by even a slight disturbance caused by winds. The fungus isectophytic, remaining mostly on the surface and draws its nutrition from theplant cells through the haustoria which penetrate the epidermal layer andreach the cells. The affected fruits do not grow in size and may drop beforeattaining pea size. In Bangalore area, the disease has been found to beprevalent almost throughout the year on varieties like Pairie and Alphonso.

In Indo-gangetic region the infection is occasionally found on malformedinflorescences and there is a likelihood of its survival in the sub-mountainousregions of Uttar Pradesh. Warm temperature with heavy morning dew andcloudy weather favour the disease development. The minimum, optimum andmaximum temperature for conidia germination is stated to be 9, 22 and 30.5°Crespectively (Uppal et al. 1941). The disease appearance and incidence is greatlyinfluenced by the sunshine (hours) per day and it is inversely proportional tothe disease having a correlation coefficient of r =0.5943. The other factorsinfluencing the disease was relative humidity at 1430 hours (Rawal and Saxena1992).

The most effective method of control is by dusting the plants with finesulphur (250-300 mesh) at the rate of 1-3 lb. of sulphur/tree (Cheema et al.1954). The first application may be soon after flowering, second 15 days laterfollowed by a third one. Spraying of Guesarol (405.50) has been foundsuccessful in Tamil Nadu, Andhra pradeeh and Maharashtra. Severalfungicides, such as Cosan (0.2%), benlate (0.2%), wettable sulphur and DDT(2:1), karathane or morestan, carbendizim (0.1%), 0.2% microsul and butrimate,Baycor, Calixin, Anvil (0.05%), Systhane (0.05%), Saprol (0.2%) were found tobe effective in controlling the disease.

Anthracnose: This is caused by Colletotrichum gloeosporioides Penz. =Glomerella cingulata (Sten.) Spould and Shrenk., Gloeosporium mangiferaeP. Henn and is the most important disease wherever mango is grown. Thedisease develops on all the tender parts of the plant and is especially seriouson tender twigs, flowers, flower stems and fruits in storage.

In India, it is widely distributed in Bihar, Punjab, Maharashtra, Gujarat,Kerala, Uttar Pradesh, Rajasthan and Karnataka. The disease produces leafspot, blossom blight, wither tip, twig blight and fruit rot symptoms. Youngleaves when attacked wither and dry up. Sometimes only the edges of the


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leaves are attacked; their margins darken, dry up, may fall out, giving theleaf a rugged appearance. It produces a wither tip of young tender twigs. Italso results in a die-back which appears as blackish spot on the growing tips.The affected branches ultimately dry up and infections keep on penetratingdown.

On fruits, most of the infection takes place from the start of the blossomingperiod until the fruits are more than half grown. The spots appear near thestem end as small brown areas that enlarge rapidly and become black. In somecases, the areas involved are in the form of streaks running down from thestem end. The affected areas usually crack and sink slightly.

The decay is confined to the skin of the fruit except in late stages when itpenetrates the flesh in shallow areas. The latent infection (during ripening) iscarried from the field and develops further which causes rotting in the storage.Healthy fruits develop infection after coming in contact with diseased fruits.The inoculum remains on dried leaves, defoliated branches and mummifiedflowers and flower brackets. The severity and prevalence of the disease isinfluenced by excessive rains, heavy dews or high humidity during criticalinfection period. The temperature range for disease development 10-30°C, andthe R.H. 95-97% are highly congenial. Spotting of leaves and twigs whichbecome severe in damp weather are generally not serious enough to causewither tip and die back in full grown trees (Kausar et al. 1960). The secondaryspread is through rain drops.

Only one variety, namely, Edward has been reported to be resistant(Brooke and Olmo 1957). In Uttar Pradesh, anthracnose was effectivelycontrolled by spraying with carbendazim (1%) or Topsin-M (0.1%) orchlorothalonil (0.2%) at 14 days intervals until harvest. Benlate (0.2%) andDithane Z-78 (0.2%) are extremely toxic to fungus in culture.

However, these have not been tested in the field. Spraying of Micop, Blitoxand dithiocarbomate were found effective. Bordeaux mixture (1.0%) has beenrecommended. Application of Captan (3 g/l) or Phaltan (2g/l) are alsorecommended.

For the control in storage, the management strategies recommended tocontrol anthracnose include cultural practices, tree management, varietalselection and protective sprays using curative fungicides with advantage thatsprays need only to be applied after infection occur and using prochloraz anddisease detection instrument known as mango anthracnose estimator (MAE)(Fitzell and Peak 1985). Hot water treatment has also been recommended byvarious workers which is 51.5°C for 15 minutes (Pennock and Maldonaldo1961); 50.5-55.5 °C for 5 minutes (Soot and Segall 1963); 54-55°C for 15 minutes(Tandon and Singh 1968) and 55°C for 5 minutes added with Benomyl or TBZ(Spalding and Reeder 1972).

Anthracnose would be controlled by dipping the fruits in variousfungicides or exposing them to ammonia, sulphur dioxide and carbon dioxide


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gases and also by hot air treatment (Tandon and Singh 1968). The fruitdipping in benomyl solution (9500 ppm a.i) or thiobendazole (1000 ppm)immediately before storage reduces the disease to 5 per cent from 29 per cent.Pre-harvest spraying with Bavistin (0.1%) or Topsin-M(0.1%) or Prochloraz(0.1%) followed by dipping in the same after harvesting have also been foundto be effective.

Mango Malformation (Fusarium Moniliforme var.Subglutinans Sheldon)

It is the most important malady of mango and was first reported byBurn (1910). It causes the losses from 50-80 per cent. It is also reported to bedue to other disorders like physiological and acarological. Indications of itsvirus nature has also been postulated. The maximum incidence of the diseasehas been recorded in the north, northwest and north-east parts of the country.

The incidence is, however, less in western and southern India. There aretwo types of symptoms, namely, floral malformation and witches broom orbunchy top or vegetative malformation with a proliferation of infected tissue.The flowering panicles turn into a compact mass of flowers. This compactmass is very hard and not soft like normal panicle. Individual flower is greatlyenlarged and has a large disc. The percentage of bisexual flowers in malformedpanicles is very low. In bunchy top, compact leaves are formed in a bunch atthe apex of shoot or in the leaf axil. A similar bunch consisting of smallrudiments crowded together on short shootlets is seen in vegetativemalformation in which the growth of shootlet is arrested. Vegetativemalformation is more pronounced in young seedling and seedling trees. Themalformed heads dry up in black masses and persist on the trees for a longtime. The malformed inflorescences contain more of endogenous cytokininsthan healthy ones.

The variety Zebda has been reported to be resistant in Egypt (El Ghandouret al. 1979). Considerable incidence reduction has been reported by spraying100-200 ppm NAA during October. Use of disease free planting material andprophylactic spray of insecticides and fungicides can keep the orchardshealthy. In areas with less than 5-10 per cent infection, pruning of diseasedplants should be made compulsory; pruning of diseased parts along the basal15-20 cm apparently healthy portions. This is followed by the spraying ofBavistin (0.1%) or Captaf (0.2%). Partial control of malformation has beenachieved by spraying mangiferin-Zn2 and mangiferin-Cu2+chelates.

Stem End Rot (Botryodiplodia theoBromae Pat)

It is an important disease of ripe mango. This fungus also causes die-back symptoms in orchards. It is known to occur in India, Myanmar, Sri Lanka,the Philippines, Mauritius and the U.S.A. In India, it is recorded from all themango growing areas. The disease is characterized as the dark epicarp around


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the base of the pedicel in the initial stage. In the next few hours, the affectedarea enlarges to form a circular, black patch which in humid atmosphereextends rapidly and turns the whole fruit completely black within two orthree days. The pulp of the diseased fruits become brown and somewhatsofter. The diseased fruits showed increased phosphorus and reduced ascorbicacid contents (Desai and Pathak 1970). Pectolytic enzyme activity was alsolowered in such fruits (Pathak and Srivastava 1969). The disease is carriedfrom the dead twigs and bark of the trees harbouring the pathogen and withthe onset of rains the orchards get contaminated.

Dipping of mangoes in 6 per cent borax solution at 43°C for 3 minutesreduces the incidence (Thomas and Dalai 1968). Fruit dipping in Aureofunginand wrapping was also found effective (Dharamvir et al. 1967). Pathak (1980)suggested to harvest mangoes on clear dry day. Hot water treatment at 53°Cfor 10 minutes (Quimio and Quimio 1974) and at 51 to 55°C for 15 minuteshave been recommended elsewhere. Care should be taken to preventsnapping-off of the pedicels. Injury should be avoided to fruits at all stages ofhandling. Spalding (1982) in his experiments found thiobendazole andthiophenate methyl to be the most effective ones. Recently, Rawal and Ullasa(1988) have reported that Bavistin (0.1%) or Topsin-M (0.1%) or chlorothalonil(0.2%) spraying in the field before harvesting give very effective control.

Die-back (Botryodiplodia Theobromae Pat)

It is a descructive disease of mango and is known to occur in India andother mango growing countries. The disease is manifested by discolourationand darkening of the bark some distance from the tip of the twigs. The darkarea advances and young green leaves start withering first at the base andthen extending outwards along the vein. The affected leaves turn brown andthe margins roll upward. At this stage, the twig or branch dies, leaves shriveland fall, and this may be accompanied by exudation of gum.

The infected twigs show internal discolouration. Brown streaks of vasculartissues is seen on splitting the twigs lengthwise along the long axis. In earlystages, epidermal and sub-epidermal cells of twigs appear slightly shrivelled.The areas of cambium and phloem show brown discolouration and yellowgum like exudate flows out of the cells.

The disease is known to be enhanced by a beetle, Xyleborus affinis.Relative humidity above 80% and temperature of 25 to 31.5°C, and rainsenhance disease development. The die-back is also caused due toColletotrichum gloeosporioides. Both these pathogens also attack fruits whichget spoiled during ripening.

For effective control of the disease, pruning and destruction of infectedtwigs is the foremost practice. Spraying the trees periodically with copperoxychloride sulphate is recommended by Alvarez and Lopez (1971). Pastingof trees with a mixture of oil and 5% phenol was found effective. Sprays of


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carbendazim (0.1%) or methyl thiophenate (0.1%) or chlorothalonil (0.2%)at fortnightly interval during rainy season is important. Sometimes shorthole borers also predispose the trees to infection and hence proper insecticidesare also to be sprayed. Healthy twigs should be selected for grafting of seedlingduring propagation.

Leaf Blight (Macrophomina Mangiferae Hingorani & Sharma)

It was first reported from Brazil to be caused by Macrophomina sp. byLacca (1922). In India, it was reported by Patel et al. (1949). Later, it has beenreported by various workers from Delhi, U.P. and Gujarat. The otherpathogens causing the disease are grey blight (Pestalotiopsis mangiferae),phoma blight (Phoma glomerate), and twig blight and fruit rot (Phoma sp.).

The disease usually appears as yellowish pin head like spots on leavesand twigs of the affected plants. These gradually enlarge discolouring thesurrounding tissues which first become brown and then dark brown withslightly raised and brown purplish margins and later ash coloured due to theappearance of pycnidia.

Spots are round to start with but later become oval or irregular in sizedepending upon environmental conditions such as humidity and temperature.Infection is mainly observed on leaves and rarely on stems. On stem, thelesions are elliptic which later girdle the stem at the point of infection. Onfruits, water soaked circular lesion are produced which enlarge rapidly andcause rotting. The pathogen can survive for more than a year on the leaves ofmango (Hingorani et al. 1960). The varieties, namely, Khandeshi, Borasio andAsal Damido are reported to be resistant (Desai and Patel 1963). Fieldsanitation is by collecting and destruction of diseased parts. Spraying ofBurgandy mixture, Perenox, lime sulphur and dithane have beenrecommended by Hingorani et al. (1960).

Red Rust (Cephaleuros Mycoides Karst)

This or red spot is a common algal disease on the mango in the tarai andin the other humid regions of India. Its occurrence has been reported fromBihar, Karnataka and Uttar Pradesh. The alga attacks the foliage, bark andtwigs of the host plant and is both parasitic and epiphytic in nature. In seriousinfections, the bark becomes thickened, the twigs get enlarged and remainstunted and the foliage becomes sparse and finally dries up. Initially the spotsare greenish-grey in colour and velvety in texture, but later on the surfacebears reddish-brown appearance. Algal spot is circular to irregular in shape,slightly elevated and with usually 2 mm in diameter, though in some cases itmay be as much as 1 cm. Bordeaux mixture (6:6:100), Supramar, Fytolan,Blitox-50 or lime sulphur are recommended.

Black Spot (Xanthomonas Campestris pv Mangiferae Indicae)

It is one of the serious diseases and is reported from many countries. In


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India, it is reported from Maharashtra, Delhi, Uttar Pradesh, Tamil Naduand Karnataka. It affects leaves, petioles, fruits and tender stems. Numeroussmall angular water soaked lesions appear in groups towards the tip of theleaf blade.

These are first light yellowish but later turn dark brown to black and getsurrounded by a distinct halo. Several lesions are often found to coalesceforming large necrotic spots. On young fruits, water-soaked lesions developwhich also turn dark brown to black. Infected fruits may show skin crackingand badly affected ones dry prematurely. Infection by wounding producesdiseased spots on tender stems, petioles and stalk bearing fruits. These spotsturn into deep longitudinal scars accompanied by appreciable amount ofbacterial gum-like ooze. The incubation period on leaves varies from 2-14 days.

In India, the disease remains dormant during November to March dueto low temperature (11.8-22°C) and the leaf infection is considerably reducedby the fall of the infected leaves. Kent mangoes showed close relationship ofrainy season with incidence of bacterial leaf spot. One day's rainfall did notaffect the disease appearance, whereas four days of rainfall led to the 36.9%disease incidence.

Twig canker persists and initiates fruit infection. The disease spread israpid during the rains and becomes severe in July-August. Five applicationof Bordeaux mixture (4:4:50) with spreader was recommended by Wager(1937), whereas four sprays of 6:6:50 Bordeaux mixture was found to beeffective by Marloth (1947). Sprays with fungicides such as copper containingmaterials and agrimycin (Viljoen and Kotze 1972) have also been advocated.Shekhawat and Patel (1975) recommended orchard sanitation by way ofremoval of infected materials and seedling treatment as preventive measures.Agrimycin-100 proved best in arresting the disease development. Plantomycin(200 ppm) followed by agrimycin + bavistin (1000 ppm) was reported to bethe best against this disease. Streptomycin sulphte followed by aureofunginhave been recommended by Prakash and Raooff (1985) to control bacterialdisease of mango.

Black Mould Rot (Aspergillus Niger Van Teigh)

The affected fruits show yellowing of base and development of irregular,hazy, greyish spots and coalesce into dark brown or black lesions. Themesocarp of the rotted areas becomes depressed and soft. The diseased fruitsshow rapid decrease in ascorbic acid content. The pathogen infects injuredfruits. Totapuri variety is highly susceptible. A fruit dip treatment with benlateat 1500 ppm can control the rot (Bhargava and Singh 1975).

Soft Rot (Rhizopus arrhizus Fisc.)

This pathogen alone is reported to be responsible for the decay of 6.3 percent fruits in Delhi markets (Thakur and Chenulu 1966). The pathogen incites


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a typical soft rot. Development of disease is slow and less intensive at lowtemperature (7-8°C). The disease develops rapidly between 20 and 40°C.Thakur and Chenulu (1970) found that 2-aminothiozole with 2-aminopyridineeach at 7 per cent concentration protected mango fruits for 20 days.

Some of the other post-harvest diseases and pathogens are Alternaria rot(Alternaria tenuissima (Neer. Ex. fr.) Wiltshire), Sclerotium rot (Sclerotiumrolfsii Sacc.), dry rot (Boothiella tetraspora Lodhi and Mirza), brown rot(Pestalotiopsis mangiferae P. Henn. and P. glandiola (Cast) Stey), fruit rot(Phomopsis mangiferae Ahmed) and black spot, Actinodichium jenkinsii.

Black Tip : This disease is peculiar to India and does not occur in anyother country. It has been reported to occur in regions of West Bengal, UttarPradesh, Bihar and Punjab in orchards located in close proximity of a brickkiln. South India is free from this disease. The symptoms manifest as smalletiolated area at the distal end of the fruit, which gradually spreads, turnsnearly black and covers the tip completely. Before the etiolation is complete,isolated greyish spots appear which become dark brown, enlarge and coalesceinto a continuous necrotic area. The brown discolouration spreads to theneighbouring parenchyma and the deposits also appear in the ducts. Thebrowning and deposits gradually spread throughout the mesocarp and theaffected cells distintegrate and coalesce into a dead tissue. In severe cases,the necrosis extends to the endocarp.

The practical control measure lies in keeping the brick kilns away fromthe mango orchards. The use of telescoping chimney 12-15 m high has alsobeen recommended. Spraying of borax (0.6%) at 10-14 day intervals has beenrecommended (Reddy and Kapoor 1965).

Soft Nose : The problem was first observed as physiological breakdownin cvs. Kent and Haden by orchardists in 1950 in Florida. The soft nose ischaracterized by hallowing of the green skin in the areas between the apexand the stigmal point. A lack of firmness in diseased fruits can also be feltwith experience. Upon cutting the flesh on the ventral side towards the apexof some soft nose fruits appear to be over ripe, while on shoulder and dorsalside it is unripe. The over ripe flesh surrounds a mass of yellowish to browntissue which is firmer than the surrounding affected tissue and is bitter intaste.

Young (1957) concluded that the disorder is not due to themicroorganisms. However, Young et al. (1963) reported the loss of only fewpercent in fruits harvested from trees grown on calcareous rock soil, but onacidic soil, sandy soil it is common for 15-20 per cent incidence. According toYoung et al. (1963), soft nose disorder increased with N fertilization but wasreduced to greater extent by increasing Ca level of the soil. Nitrogen fertilizerin sandy acidic soil increased the incidence whereas in calcareous soil therewas no effect.

To overcome this disorder, the high N level of soil should not be allowed


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in the sandy or acidic soil and proper Ca level should also be maintained insoil. Early picking is also suggested. The other disorders are little leaf causedby zinc deficiency, tip burn due to moisture stress and salt accumulation insoil and leaf scorch due to accumulation of chloride ion in leaf.

Phanerogamic Parasites (Dendrophthoe (Loranthus) viscum) : The mangotrees are severely affected by this parasite particularly in neglected orchards.They are commonly present on the trunk or branches of the trees. The foliageof the infected tree is sparse, reduced in size and its bearing capacity andquality of fruits is considerably reduced. The fruits of this parasite are baccatewith viscous mesocarp and attract the birds by its attractive colour. The seedsof this parasite are spread through bird and animal droppings. Such seeds,germinate and produce haustoria. Sometime tumour like swellings areobserved on the affected tissue. There are many other species of parasiteswhich also attack mango trees. All epiphytic plants can be removed easily inearly stages before their aerial roots penetrate the ground and surround thehost trunk.

Some more diseases reported by various workers attacking the mangocrop in the field are leaf spots due to Rhizoctonia bataticola (Taub) Butt.,Cercospora mangiferae indica Munjal Lal & Chona, Alternaria alternata Fr.& Keissler, Phoma sorghicola (Sacc.) Boerema. Dorem and Venkast; Scab(Elsinoe mangiferae Bit & Jen; black band (Rhinocladium corticolum Massee);pink disease (Pellicularia solmonicolor Dastur); root rot and damping-off(Rhizoctonia solani Kuhn) and wilt due to Verticillium albo-atrum Reinke andBerth and Fusarium solani (Mart.) Sacc. There are several more fungi causingdifferent diseases but the above are the most important among them.

POLLEN STORAGE IN TROPICAL FRUITS

Genetic conservation through pollen storage is desirable for a variety ofhorticultural plant species, since pollen is known to transmit importantgenetically heritable characters. Pollen is a product of genetic recombinationand can provide a reliable source of nuclear genetic diversity at the haploidstage.

Although genetic conservation through pollen storage does notaccomplish the whole genome conservation, a plant breeder involved ingenetic enhancement of a given horticultural crop could have access to afacility called Pollen Cryobank, from where he can draw pollen parents of hischoice in the process of breeding a new cultivar.

Pollen genepools can provide sources of resistance for exchange withother breeders. Exotic nuclear genetic diversity can be easily received andexchanged through pollen, thereby eliminating the need to go through a longjuvenile phase, common in most fruit trees to produce pollen for hybridizationat a desired location. Thus, stored pollen can be used to improve breeding


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efficiency. Plant breeding strategies could derive the benefit of pollen selectionwhen samples having increased longevity are indexed as viable and fertilefor carrying out breeding operations throughout the year.

Fruit tree pollen is generally required to be stored for controlled crossings,either to achieve a desired breeding objective, or to overcome a constraintinvolved in commercial fruit production. For example, in Citrus rootstockbreeding programme, interspecific or even intergeneric crosses are attemptedto introgress genetic traits into the desirable cultivated plants from pollenparents known for providing resistance to biotic stresses. Citrus and its alliedspecies flower asynchronously and successful crosses are seldom accomplishedwith fresh pollen due to non-availability of the seed parent when the pollenparent is in full bloom. Pollen storage has come to the rescue, where storedpollen indexed as viable can be used in crossing with the desired female cloneso as to accomplish the breeding objective.

Successful transfer of trifoliate leaf character to the F1 zygotic hybrids ofan intergeneric cross involving Poncirus trifoliata as the pollen parent andCitrus limonia as seed parent, using one year cryopreserved pollen(Rajasekharan et al. 1995) was accomplished. On the same lines, pollen ofmango cultivars were successfully cryopreserved for two years. Pollen fertilitywas retained for five years as tested by intervarietal crosses.

Genepool conservation at the haploid stage can, therefore, be effectivelyaccomplished through pollen which can provide a rich source of nucleargenetic diversity. A major emphasis on research needs include pollen storage(Arora and Rao 1995) for citrus, mango, rambutan, jackfruit, durian and litchi.Pollen cryopreservation research has been recently recognized by IPGRI. Asone of the genepool components in an integrated PGR conservationprogramme, pollen can serve as an alternative or additional ex situconservation method. Alexander and Ganeshan (1993) have extensivelyreviewed pollen storage research in fruit crops. Grout and Roberts (1995) haveelaborately described the methodology involved in pollen cryopreservation.Hoekstra (1995) has assessed the merits and demerits of pollen storage forgenetic resources conservation. The present lecture will give an insight onresearch progress made at IIHR with respect to citrus and mango pollenstorage.

CIT RUS

Pollen Collection : The species handled for pollen collection include Citruslimon, Citrus aurantifolia, Citrus sinensis and Poncirus trifoliata.

Inventory : Petri dishes, butter paper, forceps, muslin cloth fixed to a 10cm. cylindrical ring with the help of a firm rubber band, clean razor blade,etc.

Procedure : Pollen collecting are usually made on a bright sunny daybetween 8 - 10 AM, staminate flowers are harvested at peak anthesis and the


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dehiscing anthers are gently caressed over a muslin cloth sieve. Anthers arecarefully removed from pistillate flowers and pollen is extracted over a muslincloth sieve. Thus, pure pollen is extracted in clean petri plates or butter paper.

Precautions : The following points should be noted:1. Quality of pollen collected depends on the correct stage of anthesis/

anther dehiscence.2. Pollen should be free of anther debris.3. Do not collect pollen from infected or insect damaged flowers.4. Decide upon bagging of inflorescence depending on insect activity.5. Do not venture to collect pollen on a rainy day or if it had rained

overnight.6. Do not force out pollen from anthers.Viability Testing : Pollen collections are subjected to viability indexing

by germination in vitro by the hanging drop technique (Shivanna andRangaswamy 1993). This process involves suspension of pollen grains in adrop of liquid medium consisting of a carbohydrate source, inorganic andorganic compounds.

Inventory : Cavity slides, cover glasses (22 mm square), microslides,petroleum jelly, large petri plates, filter paper discs, incubator, double distilledwater, needle, forceps, "Quick fix" (epoxy resin).

Medium : Prepared in deionised, double distilled water. 20% sucrose, 100ppm H3BO3, 300 ppm Ca(NO3)24 H2O, 200 ppm Mg SO4 7H2O, 100 ppmKNO3, pH 7.3.

Procedure : Apply petroleum jelly to the edges of a new cover glass. Placethis cover glass on the work table so that the edge on which petroleum jelly isapplied faces the roof. Place a 25 to 50 l drop of nutrient medium on the centreof the cover glass assuming the shape of a small bubble. Add pollen grainswith the help of a needle carefully filling the drop with optimum quantity ofpollen. Invert a cavity slide over the cover glass with the cavity over the drop.

The petroleum jelly helps to adhere to the cover glass around the cavity,sealing the cavity from all sides. Reverse the cavity slide and place in a petriplate fixed with moistened filter paper disc cut to its exact size. Place the cavityslide over a microslide in such a way that the cover glass with the hangingdrop over the cavity is well clear of its surrounding area, intact and hanging.Cover petri plate with the top lid (also fixed with moistened filter paper) andkeep in an incubator at 25 ± 2°C, dark, for 18 to 20 hours.

After the prescribed duration of incubation, the hanging drop preparationis separated carefully from the cavity slide. After removing the residualpetroleum jelly from the slides of the cover glass, a drop of Alexander'sdifferential stain is added over the stained drop and mixed slowly. Place aclean microslide over the stained drop. The drop is flattened with the coverglass sticking to the underneath of the microslide. Remove excess stain andseal the edge of the cover glass microslide interface with a thin layer of quick


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acting adhesive. The slide with germinated pollen is ready for observationsunder the microscope for qualitative and quantitative viability estimates.

Precautions : Noteworthy points are:1. Prepare medium fresh.2. The medium on the cover glass should be just optimal for it to

hang on the cover glass when inverted.3. Add just enough stain to the drop containing germinated pollen.

If excessive stain is added, the germinated pollen drifts away outsidethe cover glass when the drop is flattened, leading to errors inquantitative estimation.

Storage

Inventory : Butter paper, glass vials, silica gel, gelatin capsules,polyethylene aluminium laminated pouches, head sealer, domesticrefrigerator, freezer, liquid nitrogen storage, cryoflask filled with liquidnitrogen.

Procedure : Pollen samples are packed in glass vials/gelatin capsules/butter paper packets depending on the method of storage. Lemon pollencontained in glass vials are best stored at 5 or -18°C for short duration of 8weeks (Ganeshan and Sulladmath 1983) and medium term duration of 6months with a progressive decline in viability index by germination in vitroat weekly or monthly intervals. Cryogenic temperatures (-196°C) afford muchmore prolonged duration storage, beyond two years as demonstrated byJapanese workers (Kobayashi et al. 1978). Ganeshan and Alexander (1991)reported cryogenic preservation of lemon pollen for 3.5 years.

Storage of 5°C and -18°C : Storage in liquid nitrogen: Pollen samples arepacked either in gelatin capsules or butter paper packets, sealed air tight inpolyethylene aluminium laminated pouches and lowered into a canister of acryoflask. The canister is capped with a perforated lid and plunged slowly inliquid nitrogen contained in the cryoflask. Frequent refilling of the cryoflaskwith liquid nitrogen at least once every 10 to 15 days, ensures a constantcryogenic temperature. For proper ease of operation, samples to becryopreserved for a long duration are located at the bottom of the canisterand those that are to be retrieved after a short duration, at the top of thecanister.

Retrieval and Post-storage Viability Assessment : There are not manycritical steps to be followed for retrieval of pollen samples stored at low orsub-zero temperatures. Pollen is removed from the glass vial and directlytested for viability as described above. Pollen samples retrieved from cryogenictemperatures have to be carefully pulled out of the canister with the help of aone foot long blunt forceps, held at ambient temperature for 10-15 minutesprior to a viability test or field pollination.

Pollen samples are viable if:


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• Germination profiles in vitro are as good as fresh pollen.• Germination time taken is not more than that of fresh pollen (pollen

vigour).• Estimated germination is in the range of 60 to 80 per cent of fresh

pollen.Field Pollinations with Stored Pollen for Fertility AssessmentInventory : Breeder's crossing kit.Procedure : Stored pollen are required to be tested for fertility under field

conditions through controlled pollination. For this, pollen samples retrievedfrom storage are transported to field locations in an ice box and used in crosseswith compatible seed parents in order to obtain an estimate of fertility, fruitand seed set.

Stored pollen is applied to pre-bagged emasculated perfect flowers atpeak stigma receptivity with the help of a painting brush, followed by baggingto avoid contamination with stray pollen. For comparative fertility estimates,crosses with fresh pollen must be carried out as far as possible at least initially.If the pollen parent in question is not in flowering, crosses may be repeatedwith the fresh pollen over the same seed parent within a short period.

Observations to be recorded in field are:• Number of crosses made with fresh and stored pollen.• Number of fruits set to maturity.• Number of seeds per fruit.• Number of aborted seeds.Seeds set through stored pollen are germinated and observation of any

marker characters transmitted by pollen parent (for example, trifoliate leafcharacter in F1 population of crosses involving pollen of Poncirus trifoliata),would confirm that the stored pollen was fertile and has transmitted thecharacter conserved to the next generation.

M ANGO

The species handled for pollen collection include Mangifera indica.Pollen Collection : Each inflorescence consists of several thousands of

staminate and perfect flowers, having a preponderance over staminate flowers.Anthesis is initiated much earlier to the complete development of theinflorescence:

Inventory : Petri dishes, butter paper, forceps, polythene covers (forbagging if necessary) needles, clean razor blade, etc.

Procedure : Pollen collection is usually synchronized with anthesis,between 9 and 11 AM. Anthers dehisce only after the flower is opened. Inmost Indian cultivars, staminate and/or pistillate flowers have just one oroccasionally two anthers producing viable and fertile pollen. These are about2 mm long and could be seen with the naked eye. In some cultivars, theanthers are pink, turning purple on anthesis, and in some they are dark


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maroon turning to weak ash-grey colour which is "pollen covered" on thedehisced anther. Pink or dark maroon anthers are picked out from each flowerusing a fine pair of forceps and kept on a butter paper in a petri plate.Although it is a laborious process, considerable amount of such anthers areconsolidated on a butter paper kept in a petri plate, These anthers ondehiscence turn purple or ash grey. A hand lens can reveal the presence ofpollen on the dehisced anthers.

Viability Testing : Spencer and Kennard (1955), and Young (1956)reported in vitro germination of mango pollen. Germinating pollen by thehanging drop method as described for citrus or the modified cellophanemethod (Alexander and Ganeshan 1989) for recalcitrant pollen resulted in poorviability estimates (Rajasekharan 1996, personal communication). Efforts areunder way at IIHR to design a repeatable procedure for germinating mangopollen.

Storage

Inventory: Gelatin capsules, polyethylene aluminium laminated pouches,heat sealer, cryoflask with liquid nitrogen.

Procedure : Mango pollen is required for breeding only once a year andhence long term cryogenic preservation effect was investigated. Anthers ladenwith pollen were enclosed in gelatin capsules, sealed in polypouches andlowered in canisters and capped as described for citrus. Complete immersionof the samples are ensured by periodical replenishment of the cryogen.

Retrieval and Post-storage Fertility Assessment

Inventory : Field pollination kit.Procedure : Post-storage fertility of mango pollen is tested by field

pollination. At peak stigma receptivity, emasculated flowers of seed parentpreviously enclosed in polythene bags were pollinated with cryostored pollenby gently touching the receptive stigma with the anther-pollen mixture drawnfrom the gelatin capsule with the help of fine brush, followed by bagging.Fruit and seed (stone) set could be observed in the next 2 to 4 weeks.

Due to a high inherent fruit drop rate (Mathews and Litz 1992), very fewfruits develop among crosses involving cryopreserved pollen as observed inthe case with fresh pollen crosses. Cryopreserved mango pollen induced fruitand seed set among intravarietal crosses attempted at IIHR, therebydemonstrating that mango pollen could retain fertility after long termcryopreservation. Further studies on the seed (stone) set with stored pollen isin progress.

Some theoretical and practical considerations of cryogenic preservationof pollen:

1. Techniques of cryogenic storage are new to many plant species, ofwhich the success rate is very high for bicellular pollen material,


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often collected from tropical regions.2. Survival of pollen to cryogenic storage and eliciting a high viability

response can be used as a model to study the moisture kineticsinvolved in other plant tissues.

3. The cryogen used i.e., liquid nitrogen though inert, is hazardousby way of causing frost injuries with risk for the personnel using,and those who work in the surrounding area. Training in cryogenicoperations, handling procedures, safety precautions, etc., areessential.

4. Places with cryoflasks filled with nitrogen should minimise the riskof gaseous nitrogen build-up. Small volumes of liquid on expansionat ambient temperature, converts into large volumes of gaseousnitrogen, reducing the local oxygen content. This can causedrowsiness, and in extreme cases, asphyxiation.

5. Proper handling equipment, such as cryogloves, long forceps ortongs, face guards if necessary while working for long duration, isessential. It is generally advised not to use glass vials for cryogenicstorage, as they can explode due to seepage of liquid nitrogen intothe vial during storage.

6. Liquid nitrogen source as far as possible, must be located inproximity and should be easily accessible.

Cryogenic Containers

• Commercially available storage containers with a long static liquidnirogen holding time and with a low evaporation rate are desirable.The canisters designed to hold vials, pouches, etc., in liquid andvapour phase are to be used.

• It is of cardinal importance to ensure transfers or retrievals in andout of the canisters as quickly as possible, so that samples held instorage at -196°C are not allowed to warm up significantly as aresult of being relocated temporarily.

• The liquid nitrogen level in storage cryocans will have to bemonitored regularly (at least once every week and more frequentlyif the containers are often opened within this period). Accordingly,the cryogen level has to be replenished to the level recommendedby the manufacturer to achieve the required temperature. Keepingthe containers in a room temperature controlled between 0º - 10ºCreduces loss of the cryogen to a great extent, thus extending thetime between fillings.

TROPICAL AND SUBTROPICAL FRUIT CROPS

Bacterial citrus canker and now citrus greening have ravaged citrus


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plantings throughout Miami-Dade and Broward Counties and much of southFlorida. Infected trees may severely defoliate and management options arevery limited; sanitation procedures and following quarantine regulations arevery important.

Because of the highly infectious nature of these citrus diseases fruit cropsother than citrus should be considered for planting in the home landscape.For some residents, that could mean the opportunity to grow some excitingtropical and subtropical fruit crop alternatives.

The south Florida climate offers the opportunity to successfully producea surprising variety of tropical and subtropical backyard fruits. Many of themhave strange names, odd shapes and exotic flavours, particularly for those ofus who have come from up north. Yet many of these fruits are tempting,nutritious, and luscious old favourites enjoyed by the peoples of the tropicsaround the globe.

Examples include, avocado, mango, guava, and papaya or perhaps theeven more exotic carambola, jakfruit and jaboticaba. Although many of thesespecies can attain the size of large trees, routine pruning can keep them to amanageable size for most backyard situations.

The University of Florida, Institute of Food and Agricultural Sciences hasa wealth of information on how to grow and enjoy these and many othertropical and subtropical fruits right here in south Florida. Learn which varietiesare adapted to our area, recommended cultural practices, pitfalls, andpreparation techniques. An overview of some of the fruits we think localresidents might want to grow and several (guava and sapodilla) that theUniversity of Florida, IFAS does not recommend because of their invasivestatus.

Atemoya (Custard Apple)

The atemoya is a hybrid between the sugar apple and cherimoya. Itproduces a fruit very similar to the sugar apple, also called sweetsop or anon.It is a small to medium sized, open, deciduous tree with a rounded canopyrarely exceeding 20 feet in height and width.

Because of their relatively small stature, atemoya trees are suited to smallyards. A relative of the atemoya, sugar apple has similar characteristics. Thefruit is heart-shaped, round, ovate or conical, from 2 to 4 inches in diameter.The pulp is white or creamy white, with a custard-like consistency and a sweet,pleasant flavor. When ripe, atemoyas become light green or yellow-green incolour. The pulp of atemoya is consumed principally as a dessert fruit andhas an excellent flavor. It may be eaten fresh but it may also be used to makea tasty ice cream or milkshake. Season: late Aug.-Oct., sometimes Dec.-Jan.

Avocado

Perhaps one of the best known subtropical fruits, avocado trees are


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typically medium to large in size (40-60 feet), easy to grow and can producelarge quantities of fruit. Limbs are vulnerable to wind damage and can evenbreak under the weight of a heavy fruit load. The fruit is a very large berryconsisting of a single large seed surrounded by a buttery pulp.

Mature fruit are generally green, although some cultivars may be black,red or purple when soft (ripe). Avocados do not ripen until they are pickedor fall to the ground. Mature fruit size varies considerably depending uponcultivar and growing conditions. Avocados are highly nutritious. Fruit arepopular eaten fresh, in salads or used to make guacamole and other dishes.Planting in a well-drained site is a must, as avocados do not tolerate flooding.Productivity, season of maturity, cold tolerance, and disease tolerance varygreatly depending upon the variety under consideration. Season: late May toMarch.

Banana

A true tropical favourite, bananas are perhaps the best known of thetropical fruits. There are many different cultivars available with a widevariation in fruit type and quality. Bananas are not cold tolerant and somevarieties are better adapted to south Florida than others. Growth is extremelyrapid during the very warm, wet summer months. Because they reproducefrom underground rhizomes and not seed, a single plant can quickly spreadout producing multiple trunks in a matter of a few months.

Fruits develop in clusters on the end of flower stalks usually within 1-2years. Shortly after bearing, the stem dies. Bananas like full sun and moistbut well drained soil.

They will tolerate partial shade, but best growth and fruit production isin full sun. Bananas may be eaten fresh, fried, baked, and added as acomponent to deserts and drinks. Season: year round.

Caimito (Star Apple)

Native to Central America and the West Indies, this evergreen tree ishighly ornamental and produces a sweet purple or green fruit. Trees mayreach 25 to 100 ft. in height and have a dense, broad crown. The attractiveleaves are glossy and green on the upper surface and golden brown on theunder surface. Trees produce either light green or purplish coloured fruit.The fruit is round, 2-4 inches in diameter, and may have a dark-purple orwhite flesh. The flesh is milky, sweet, and gelatinous and surrounds up to10 seeds. Plant trees in a well-drained soil and sunny location. Season:Jan.-June.

Carambola (Star Fruit)

Originally from southeast Asia, star fruit is becoming increasinglypopular and available in the U.S. Locally, commercial production occurs in


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the southern half of south Florida. Trees are generally small to medium inheight (35 feet max.) and spreading with the majority of fruit borne onbranches in the mid-canopy region. The fruit is a large fleshy berry, 2-6inches in length, yellow skinned with a waxy surface and star-shaped crosssection.

Flesh is light to dark yellow, translucent, crisp and very juicy. Bettercultivars have a nice, slightly sweet to subacid flavor. Eat fresh, cut up infruit salads, or as an iced juice drink. The fruit may also be canned, preserved,and dried.

Carambola trees also have ornamental value with their dark green foliageand attractive flowers and fruit. Plant in a well-drained soil and sunny location,which has protection from wind. On alkaline soils (those with high pH) watchfor signs of minor element deficiencies, particularly zinc, iron, and manganeseand treat accordingly. Season: July-September, Nov.-Feb.

Canistel (Egg Fruit)

Native to southern Mexico, Belize, Guatemala, and El Salvador, thisevergreen tree is ornamental and produces a sweet yellowish-orange top-shaped fruit. Trees may reach 25 ft. or so in height with leaves mostly groupedat the ends of branches. The attractive lanceolate-shaped leaves are glossyand green. Trees produce 3-5 inch long by 2-3 inch diameter, conical-shapedfruit. The maturing fruit changes from green to light green to golden-yellowor pale orange-yellow at maturity. After picking allow fruit to become softbefore eating. Soft fruit will have a yellow-orange flesh, which is smooth witha sweet to musky flavor. Eggfruit is eaten fresh and used in making milkshakes. Plant trees in a well-drained soil and sunny location. Season: Dec.-May.

Jaboticaba

Native to Brazil, jaboticaba is an unusual tree that produces a purple,grape-like berry directly upon the trunk and larger branches either singly orin clusters. Under the skin is a whitish pulp with 1 to 4 seeds. The fruit has apleasant flavor and taste a bit like grape. They can be eaten fresh or madeinto jam, jellies or wine.

Flowering and fruiting occur periodically throughout the year so multiplecrops are produced. Other than its fruit, jaboticaba is known for its beautifulmulticolored bark, which gives it value in the landscape. The tree is small,slow growing, and bushy, and seldom exceeds 20 feet in Florida. Flowers aresmall and white, interesting but rather inconspicuous and borne right on thetrunk and larger branches. Jaboticaba is relatively hardy but will not toleratedrought.

Plant in full sun in a moist but fairly well drained soil. The tree prefers aslightly acid soil, so some special attention will be required to provide the


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proper nutrition on our alkaline soils. If provided with an ideal growingenvironment, jaboticaba can be a relatively low maintenance tree requiringlittle pruning or spraying for pests. Season: variable.

Jackfruit

Native to India and Malaysia, this attractive large tree has glossy, darkgreen leaves and produces a very large, oval shaped, rather unusual lookingsegmented (spiked) fruit. Typically, fruit are produced in clusters of 2 or moreat various height intervals along the trunk. The skin of the fruit must be peeledto reveal the succulent, yellow to orange coloured pulp. Because of sticky latexin the peel, coat your hands with vegetable oil prior to peeling a jackfruit.This will make clean up a lot easier. The flavor is sweet, not unlike that ofbanana or pineapple, but with a strong, fruity aroma and taste. Fruit may beused fresh, fried green, pickled or roasted (seeds). Jackfruit must be plantedin flood free, well-drained soils. In south Florida, jakfruit trees have few seriouspest or disease problems. Season: spring-fall (some all year round).

Longan

Indigenous to Mayanmar (Burma), southern China, southwest India, SriLanka, and the Indochinese peninsula, longan is large tree (30-40 ft.). Longanis an excellent fresh fruit with a pleasant, unique, sweet flavor. Fruit are relativesmall (about the size of a typical strawberry), round to oval, and borne inloose clusters. When fruit are ripe, the leathery skin develops an attractivegolden brown colour. Longan trees are attractive having a dense, round toupright, symmetrical canopy of dark green foliage. They may grow as highas 40 feet. Plant in sunny, well-drained sites. Trees may begin to bear within3-5 years of transplanting. However, unreliable bearing is a major constraint.Season: July-Aug.

Lychee (Litchi)

Lychee trees are native to southern China and southeast Asia and maygrow to 40 or more feet in height. Lychee is an excellent fresh fruit with apleasant, sweet flavor. Fruit are a relatively small (about the size of a typicalstrawberry), round to oval, and borne in loose clusters. When fruit are ripe,the leathery skin develops an attractive pinkish red colour. Lychee trees areattractive having a dense, rounded, symmetrical canopy of dark green foliage.They may grow as high as 40 feet. Plant in sunny, well drained sites, preferablywhere there is some protection from wind. Trees may begin to bear within3-5 years of transplanting. However, unreliable bearing is a major constraint.Season: June, early July.

Mamey Sapote

Native to Mexico and the Central American lowlands, mamey sapote trees


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are large and erect reaching a height of about 40 feet in Florida. Mameysapote makes an excellent specimen tree in the home landscape with handsomeglossy foliage. The fruit has a brown, scurfy peel and the flesh of mature fruitis salmon pink to reddish brown in colour and has a unique, sweet flavor.The tree grows well in a variety of soils, but requires good drainage. Mameysapote can be eaten fresh, and is also excellent for use in ice cream, sherbets,jellies, and preserves. Milkshakes may also be prepared from the flesh. Itrequires little care and yields a useful, good tasting fruit. Occasionally, aninsect known as the Cuban May beetle may cause some defoliation. Season:Jan.-Sept. (some all year).

Mango

Mango trees are native to southeast Asia and India. Hardly a new comerto Florida, mango trees have been planted and enjoyed for over 100 years inFlorida.

Mango trees are medium to large trees (up to 100 ft.) and there is a widevariety of cultivars available with varying shapes, colours and maturities. Mostmangoes are ripe when the fruit softens slightly and takes on a yellow toorange or red colour and carries a subtle sweet fragrance. Mangoes are a goodsource of vitamins A and C. They can be eaten fresh or pureed. Perhaps morethan any other tropical fruit, mangoes are readily available at many localnurseries and garden centres. Trees are tough and relatively easy to grow.Most varieties of grafted trees will bear in as little as 3-5 years aftertransplanting. Season: May-Oct.

Papaya

Indigenous to southern Mexico, Central and South America, papayaplants are relatively short lived (1-3 years) and are easily propagated fromseed. Papayas are relatively easy to grow so long as they are sited in full sunand have excellent drainage.

Common throughout the tropics, papayas are small to large fruits bornon the stem of upright semi-herbaceous trunks. Fruit are sweet, have orangeto reddish-salmon coloured flesh and contain numerous small black seeds inthe interior cavity. Papaya fruit is typically peeled, sliced and consumed fresh.Papaya ring spot virus can be a problem causing stunting and fruit loss; atpresent there is no control for this disease. Papaya fruit fly is another problembut can be overcome by placing a 3-5 pound paper bag over developing fruit.Amend the soil with plenty of organic matter and fertilize often. Season: yearround.

Passion Fruit

Native to South America, passion fruit is a vigorous vine that producespurple, yellow, or reddish coloured fruit containing seeds surrounded by an


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orange, sweet, watery pulp. The juice is very aromatic and is commonly usedto make juice or punch. Plant vines next to a fence or along a trellis in a welldrained soil area with full sun. Vines begin to bear within 3-6 months ofplanting. Season June-Dec.

Sugar Apple (Annona, Sweetsop)

Native to tropical America, the sugar apple, is also called sweetsop oranon, has been widely planted in home gardens of south Florida because ofits high quality fruit. It is a small, open, deciduous tree with a rounded canopy,rarely exceeding 20 feet in height and width. Because of their small stature,sugar apple trees are suited to small yards. The fruit is heart-shaped, round,ovate or conical, from 2 to 4 inches in diameter. The pulp is white or creamywhite, with a custard-like consistency and a sweet, pleasant flavor. When ripe,sugar apples become light green or yellow-green in colour. The sugar appleis consumed principally as a dessert fruit. A relative of the sugar apple calledatemoya has similar characteristics to sugar apple. The pulp of sugar applehas an excellent flavor and is usually eaten fresh but it may also be used tomake tasty ice cream or milkshakes. Season: July-Sept., Nov.-Jan.


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6

Soil Quality in Vegetable andFruit Production

ORGANIC MATTER TO REPLENISH THE SOIL

Carrots and onions are prime examples of low-residue crops that leavelittle organic matter to replenish the soil after harvest. Potatoes produce highamounts of organic matter per acre, but most is removed in the tubers.Radishes and leafy crops like lettuce and spinach have short growing seasonsand return little residue even with multi-cropping. To compound the challengeof maintaining SOM, frequent and intense cultivation are generally used inthe production of these crops.

Methods discussed in the previous section for increasing SOM—reducingtillage, improving soil structure, and recycling excess plant nutrients—are allsuitable for vegetable crops. Application of manures, composts, biosolids, andother organic wastes are good ways to add organic matter. If biosolids areused, they should be low trace-metal, “clean” sludges that can be applied tofood crops with no restrictions.

Soil preparation and management operations such as preparing seedbeds,controlling and cultivating weeds, burying crop residue (e.g., for diseasecontrol), and building raised beds are important in vegetable production.These operations improve certain soil conditions that otherwise limit cropgrowth and development. However, each operation also accelerates the lossof SOM by mixing and aerating the soil. And excessive tillage severelydegrades soil structure. Loss of structure makes soil prone to compaction andrelated problems like reduced water infiltration and poor root growth. Tillageoperations should be selected carefully, because in some situations growersmust weigh short-term benefits to the current crop against long-termreductions in soil quality.

Growing cover crops and preceding vegetables with high-residue rotation

crops, such as small grains and forages, can increase SOM. In addition, manycover crops suppress weeds; legume cover crops add nitrogen; and cerealsand other grasses scavenge residual nutrients and keep them from movingoff-site. Buckwheat, sorghum-sudangrass, millets, and annual ryegrass areuseful summer cover crops that can follow early-season vegetables or precedefall crops.

Rye and millet produce large amounts of vegetative growth, addingpotentially large amounts of organic matter. It is important to fertilize ryecover crops or the subsequent cash crop adequately to avoid nitrogen tie-upduring decomposition. Common winter cover crops include small grains, suchas cereal rye, wheat, and oats. Oats often winter-kill and produce much lessdry matter but are a good cover crop for wet soils because they are less likelyto delay field operations in the spring. Hairy vetch and red clover are commonlegume cover crops. They can be grown alone or in grass/legume mixtures.

Many vegetable crops have relatively shallow, sparse root systems butare well fertilized because of their high value. This combination of small rootsystems and high fertilizer rates may lead to another potential soil-qualityproblem—the possible movement of excess nutrients to surface water orgroundwater. Following a good soil-testing programme, banding fertilizer,splitting nitrogen applications, using fertigation, and avoiding excess irrigationcan minimize unwanted nutrient movement.

No-till alternatives have not received as much attention in vegetable cropsas in agronomic crops, especially in temperate climates with cold winters.Yet, cover crops are used in successful no-till vegetable systems. Transplantinginto killed cover crops (e.g., tomato into hairy vetch) has produced the bestresults to date. Various practices to overcome the challenges of no-till vegetableproduction are being tested. For example, seeding or transplanting into livingmulches like short life-cycle medics may allow for more timely planting andstill offer the benefits of reduced tillage. These and other practices may soonbecome viable alternatives, especially in northern growing regions.

SOIL MANAGEMENT

Plants need nitrogen, phosphorus, and potassium as well asmicronutrients, but getting enough nitrogen, and particularly synchronizationso that plants get enough nitrogen at the right time (when plants need it most),is likely the greatest challenge for organic farmers. Crop rotation and greenmanure (“cover crops”) help to provide nitrogen through legumes (moreprecisely, the Fabaceae family) which fix nitrogen from the atmosphere throughsymbiosis with the bacteria rhizobia. Intercropping, which is sometimes usedfor insect and disease control, can also increase soil nutrients, but thecompetition between the legume and the crop can be problematic and wider


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spacing between crop rows is required. Crop residues can be ploughed backinto the soil, and different plants leave different amounts of nitrogen,potentially aiding synchronization. Organic farmers also use animal manure(which must be composted), certain processed fertilizers such as seed mealand various mineral powders such as rock phosphate and greensand, anaturally occurring form of potash which provides potassium. Altogetherthese methods help to control erosion. In some cases pH may need to beamended. Natural pH amemdments include lime and sulfur, but in the U.S.some synthetically compounds such as iron sulfate, aluminum sulfate,magnesium sulfate, and soluble boron products are allowed in organicfarming.

Mixed farms with both livestock and crops can operate as ley farms,whereby the land gathers fertility through growing nitrogen-fixing foragegrasses such as white clover or alfalfa and grows cash crops or cereals whenfertility is established. Farms without livestock (“stockless”) may find it moredifficult to maintain fertility, and may rely more on external inputs such asimported manure as well as grain legumes and green manures, although grainlegumes may fix limited nitrogen because they are harvested. Horticulturalfarms growing fruits and vegetables which operate in protected conditionsare often even more reliant upon external inputs.

WEED CONT ROL

After nutrient supply, weed control is the second priority for farmers.Techniques for controlling weeds include handweeding, mulch, corn glutenmeal, a natural preemergence herbicide, flame, garlic and clove oil, borax,pelargonic acid, table salt, solarization (which involves spreading clear plasticacross the ground in hot weather for 4–6 weeks), vinegar, and various otherhomemade remedies. One recent innovation in rice farming is to introduceducks and fish to wet paddy fields, which eat both weeds and insects.

Controlling other Organisms

Organisms aside from weeds which cause problems include arthropodsand nematodes. Fungi and bacteria can cause disease.

Insect pests are a common problem, and insecticides, both non-organicand organic, are controversial due to their environmental and health effects.One way to manage insects is to ignore them and focus on plant health, sinceplants can survive the loss of about a third of leaf area before suffering severegrowth consequences. To avoid using insecticides, one can select naturally-resistant plants, put bags around the plants, remove dying material such asleaves, fruit, and diseased plants, covering plants with a solid barrier (“rowcover”), hosing, encouraging and releasing beneficial organisms and beneficialinsects, planting companion plants and polycultures, various traps, stickycards (which can also be used to assess insect prevalence), and season


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extension. Biological pest control uses natural predators to control pests.Recommended beneficial insects include minute pirate bugs, big-eyed bugs,and to a lesser extent ladybugs (which tend to fly away), all of which eat awide range of pests. Lacewings are also effective, but tend to fly away. Prayingmantis tend to move slower and eat less heavily. Parasitoid wasps tend to beeffective for their selected prey, but like all small insects can be less effectiveoutdoors because the wind controls their movement. Predatory mites areeffective for controlling mites.

Several of pesticides approved for organic use have been called greenpesticides such as spinosad and neem. Generally, but not necessarily, organicpesticides are safer and more environmentally friendly than syntheticpesticides. The main three organic insecticides used are Bt (a bacterial toxin),pyrethrum and rotenone. Surveys have found that fewer than 10% of organicfarmers use these pesticides regularly; one survey found that only 5.3% ofvegetable growers in California use rotenone while 1.7% use pyrethrum. Asof 2005, the controversial and highly toxic insecticide rotenone wastheoretically approved for U.S. organic farmers, but no products had beenreviewed by the Organic Materials Review Institute. Nicotine sulfate may alsobe used; although it breaks down quickly, it is extremely toxic, nearly as toxicas aldicarb. Less toxic but still effective organic insecticides include neem,spinosad, soaps, garlic, citrus oil, capsaicin (repellent), Bacillus popillae,Beauvaria bassiana, and boric acid. Pesticides should be rotated to minimizepest resistance.

The first disease control strategy involves keeping the area clean byremoving diseased and dying plants and ensure that the plants are healthyby maintaining water and fertilization. Compost tea is sometimes promotedand can be effective, but there is concern over whether these are ineffectiveor even harmful. Polycultures reduce the ability of disease to spread. Disease-resistant cultivars can be purchased. Organic fungicide include the bacteriaBacillus subtilis, Bacillus pumilus, and Trichoderma harzianum which aremainly effective for diseases affecting roots. Bordeaux mix contains copper,which can be used as an organic fungicide in various forms. Sulfur is effectiveagainst fungus as well as some insects. Lime sulfur is also available, but candamage plants. Potassium and sodium bicarbonate are also effective againstfungus. Some plant activators, which increase plants’ defence systems, areconsidered organic although most are synthetic. Other synthetic fungicidesnot generally allowed are classified as protectants and systemics.

Standards

Standards regulate production methods and in some cases final outputfor organic agriculture. Standards may be voluntary or legislated. As early asthe 1970s organic producers could be voluntarily certified by privateassociations. In the 1980s, governments began to produce organic production


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guidelines. Beginning in the 1990s, a trend towards legislation of standardsbegan, most notably with the 1991 EU-Eco-regulation developed for EuropeanUnion, which set standards for 12 countries, and a 1993 UK program. TheEU’s program was followed by a Japan program in 2001, and in 2002 theUnited States created the National Organic Program (NOP). As of 2007 over60 countries have regulations on organic farming. In 2005 IFOAM created thePrinciples of Organic Agriculture, an international guideline for certificationcriteria. Typically the agencies do not certify individual farms, but ratheraccredit certification groups. Materials used in organic production and foodsare tested independently by the Organic Materials Review Institute.

Composting

Under USDA organic standards, manure must be subjected to properthermophilic composting and allowed to reach a sterilizing temperature. Ifraw animal manure is used, 120 days must pass before the crop is harvested.

Economics

The economics of organic farming, a subfield of agricultural economics,encompasses the entire process and effects of organic farming in terms of humansociety, including social costs, opportunity costs, unintended consequences,information asymmetries, and economies of scale. Although the scope ofeconomics is broad, agricultural economics tends to focus on maximizing yieldsand efficiency at the farm level. Mainstream economics takes an anthropocentricapproach to the value of the natural world: biodiversity, for example, isconsidered beneficial only to the extent that it is valued by people and increasesprofits. Some governments such as the European Union subsidize organicfarming, in large part because these countries believe in the external benefits ofreduced water use, reduced water contamination by pesticides and nutrientsof organic farming, reduced soil erosion, reduced carbon emissions, increasedbiodiversity, and assorted other benefits.

Organic farming is labour and knowledge-intensive whereas conventionalfarming is capital-intensive, requiring more energy and manufactured inputs.Organic farmers in California have cited marketing as their greatest obstacle.

Geographic Producer Distribution

The markets for organic products are strongest in North America andEurope, which as of 2001 are estimated to have $6 and $8 billion respectivelyof the $20 billion market. However, as of 2007 organic farmland is distributedacross the globe. Australasia has 39% of the total organic farmland withAustralia’s 11.8 million hectares, but 97 percent of this land is sprawlingrangeland, which results in total sales of approximately 5% of US sales. Europehas 23 percent of total organic farmland (6.9 million hectares), followed byLatin America with 19 percent (5.8 million hectares). Asia has 9.5 percent


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while North America has 7.2 percent. Africa has a mere 3 percent.Besides Australia, the countries with the most organic area are Argentina

(3.1 million hectares), China (2.3 million hectares), and the United States (1.6million hectares). Much of Argentina’s organic farmland is pasture, like thatof Australia. Italy, Spain, Germany, Brazil, Uruguay, and the UK follow theUnited States by the amount of land managed organically.

Growth

As of 2001, the estimated total market value of certified organic productswas estimated to be $20 billion. By 2002 this was $23 billion and by 2007 morethan $46 billion according to Organic Monitor.

In recent years both Europe and North America have experienced stronggrowth in organic farmland. However, this growth has occurred underdifferent conditions. While the European Union has shifted agriculturalsubsidies to organic farmers in recognition of its environmental benefits, theUnited States has taken a free market approach. As a result, as of 2007 4 percentof the European Union’s farmland was organically managed compared to just0.6 percent of United States farmland.

IFOAM’s most recent edition of The World of Organic Agriculture:Statistics and Emerging Trends 2009 lists the countries which had the mosthectares in 2007. The country with the most organic land is Australia withmore than 12 million hectares, followed by Argentina, Brasil and the US. Intotal 32.2 million hectares were under organic management in 2007. For 199911 million hectares of organically managed land are reported.

In recent years organic agriculture has grown tremendously. Consideringthis rapid growth, it is within the nature of organic farming to keep it frombecoming a large scale industrial business as conventional farming hasbecome. Duram, Leslie. Good Growing. Santa Cruz: Bison Books, 2005.

Productivity and Profitability

A 2006 study suggests that converted organic farms have lower pre-harvest yields than their conventional counterparts in developed countries(92%) and that organic farms have higher pre-harvest yields than their low-intensity counterparts in developing countries (132%). The researcherattributes this to a relative lack of expensive fertilizers and pesticides in thedeveloping world compared to the intensive, subsidy-driven farming of thedeveloped world. Nonetheless, the researcher purposely avoids making theclaim that organic methods routinely outperform green-revolution(conventional) methods. This study incorporated a 1990 review of 205 cropcomparisons which found that organic crops had 91% of conventional yields.A major US survey published in 2001, analyzed results from 150 growingseasons for various crops and concluded that organic yields were 95-100% ofconventional yields. Lotter reports that repeated studies have found that


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organic farms withstand severe weather conditions better than conventionalfarms, sometimes yielding 70-90% more than conventional farms duringdroughts. A 22-year farm trial study by Cornell University published in2005 concluded that organic farming produces the same corn and soybeanyields as conventional methods over the long-term averages, but consumedless energy and used zero pesticides.

The results were attributed to lower yields in general but higher yieldsduring drought years. A study of 1,804 organic farms in Central America hitby Hurricane Mitch in 1998 found that the organic farms sustained the damagemuch better, retaining 20 to 40% more topsoil and smaller economic losses athighly significant levels than their neighbours.

On the other hand, a prominent 21-year Swiss study found an average of20% lower organic yields over conventional, along with 50% lower expenditureon fertilizer and energy, and 97% less pesticides. A long-term study by U.SDepartment of Agriculture Agricultural Research Service (ARS) scientistsconcluded that, contrary to widespread belief, organic farming can build upsoil organic matter better than conventional no-till farming, which suggestslong-term yield benefits from organic farming.

An 18-year study of organic methods on nutrient-depleted soil concludedthat conventional methods were superior for soil fertility and yield in a cold-temperate climate, arguing that much of the benefits from organic farming arederived from imported materials which could not be regarded as “self-sustaining”.

While organic farms have lower yields, organic methods require nosynthetic fertilizer and pesticides. The decreased cost on those inputs, alongwith the premiums which consumers pay for organic produce, create higherprofits for organic farmers. Organic farms have been consistently found to beas or more profitable than conventional farms with premiums included, butwithout premiums profitability is mixed. Welsh (1999) reports that organicfarmers are more profitable in the drier states of the United States, likely dueto their superior drought performance. In 2008 the UN EnvironmentalProgramme (UNEP) and UN Conference on Trade and Development(UNCTAD) issued a report which stated that “organic agriculture can be moreconducive to food security in Africa than most conventional productionsystems, and that it is more likely to be sustainable in the long-term”. Thereport assessed 114 projects in 24 African countries, finding that “yields hadmore than doubled where organic, or near-organic practices had been used”and that soil fertility and drought resistance improved.

In 2009, a review concluded that organic production was more profitablein Wisconsin, when including price premiums.

Macroeconomic Impact

Organic methods often require more labour, providing rural jobs butincreasing costs to urban consumers.


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Motivations

Agriculture in general imposes external costs upon society throughpesticides, nutrient runoff, excessive water usage, and assorted other problems.As organic methods minimize some of these factors, organic farming isbelieved to impose fewer external costs upon society. A 2000 assessment ofagriculture in the UK determined total external costs for 1996 of 2343 millionBritish pounds or 208 pounds per hectare.

A 2005 analysis of these costs in the USA concluded that cropland imposesapproximately 5 to 16 billion dollars ($30 to $96 per hectare), while livestockproduction imposes 714 million dollars.

Both studies concluded that more should be done to internalize externalcosts, and neither included subsidies in their analysis, but noted that subsidiesalso influence the cost of agriculture to society.

Both focused on purely fiscal impacts. The 2000 review included reportedpesticide poisonings but did not include speculative chronic effects ofpesticides, and the 2004 review relied on a 1992 estimate of the total impactof pesticides.

Pesticides

Most organic farms use fewer pesticides than conventional farms, somepesticides damage the environment or with direct exposure human health.The main five pesticides used in organic farming are Bt (a bacterial toxin),pyrethrum, rotenone, copper and sulphur.

Surveys have found that fewer than 10% of organic farmers use thesepesticides regularly; one survey found that only 5.3% of vegetable growers inCalifornia use rotenone while 1.7% use pyrethrum.

Reduction and elimination of chemical pesticide use is technologicallychallenging. Few organic farms manage to eliminate the use of pesticidesentirely; organic pesticides are often used to complement other pest controlstrategies.

Pesticide runoff is one of the most significant effects of pesticide use. TheUSDA Natural Resources Conservation Service tracks the environmental riskposed by pesticide water contamination from farms, and its conclusion hasbeen that “the Nation’s pesticide policies during the last twenty six years havesucceeded in reducing overall environmental risk, in spite of slight increasesin area planted and weight of pesticides applied.

Nevertheless, there are still areas of the country where there is no evidenceof progress, and areas where risk levels for protection of drinking water, fish,algae and crustaceans remain high”.

Pest resistant genetically modified crops have been proposed as analternative to pesticide use, however concerns over the safety and the longterm benefits of genetically modified food, result in the genetic modificationbeing widely opposed in the organic farming movement.


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EFFECT S ON SOIL EROSION

Crop rotation can greatly affect the amount of soil lost from erosion bywater. In areas that are highly susceptible to erosion, farm managementpractices such as zero and reduced tillage can be supplemented with specificcrop rotation methods to reduce raindrop impact, sediment detachment,sediment transport, surface runoff, and soil loss.

Protection against soil loss is maximized with rotation methods that leavethe greatest mass of crop stubble (plant residue left after harvest) on top ofthe soil. Stubble cover in contact with the soil minimizes erosion from waterby reducing overland flow velocity, stream power, and thus the ability of thewater to detach and transport sediment Soil Erosion and Cill prevent thedisruption and detachment of soil aggregates that cause macrospores to block,infiltration to decline, and runoff to increase. This significantly improves theresilience of soils when subjected to periods of erosion and stress.

The effect of crop rotation on erosion control varies by climate. In regionsunder relatively consistent climate conditions, where annual rainfall andtemperature levels are assumed, rigid crop rotations can produce sufficientplant growth and soil cover. In regions where climate conditions are lesspredictable, and unexpected periods of rain and drought may occur, a moreflexible approach for soil cover by crop rotation is necessary. An opportunitycropping system promotes adequate soil cover under these erratic climateconditions. In an opportunity cropping system, crops are grown when soilwater is adequate and there is a reliable sowing window. This form of croppingsystem is likely to produce better soil cover than a rigid crop rotation becausecrops are only sown under optimal conditions, whereas rigid systems are sownin the best conditions available.

Crop rotations also affect the timing and length of when a field is subjectto fallow. This is very important because depending on a particular region’sclimate, a field could be the most vulnerable to erosion when it is under fallow.Efficient fallow management is an essential part of reducing erosion in a croprotation system. Zero tillage is a fundamental management practice thatpromotes crop stubble retention under longer unplanned fallows when cropscannot be planted. Such management practices that succeed in retainingsuitable soil cover in areas under fallow will ultimately reduce soil loss.

CARBON DIOXIDE FERTILIZATION

Widely recognised as the matriarch of the greenhouse industry, theDutch industry spreads over some 12000 hectares. Approximately 7000hectares are to be found in the region known as the Westlands (mostlyvegetables), with a further 4000 hectares in the Aalsmeer district (mostlyfloriculture) and the remainder scattered around the country, with a


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concentration in the areas around Venlo and Emmen. The greenhouseindustry has been part of the Dutch scenery for decades. For example, inthe area of Naaldwijk, in the Westlands, glasshouses currently cover25% (or 3000 hectares) of the land area. Subsequently glasshouses arehand-in-hand with windmills and canals in representing the lifestyle ofThe Netherlands. The estimated minimum viable operation is 4000m2,though most new developments range between three and 30 hectares inscale.

England is very much a small-scale version of the Dutch industry.Greenhouse production covers approximately 400 hectares and is foundthroughout the mid to southern regions. A similar situation is found inSweden, though, the industry in Sweden is of much lesser significance thanthe British industry. In Sweden, the technology and practices are a near carboncopy of the Dutch industry, or more accurately, the Dutch industry of 10-20years ago. The most striking feature of these industries (Dutch and pseudo-Dutch) is the similarity between one operation and the next. These industriesdemonstrate a base level of technicality, which every operation has attained.In fact, the difference in technology at the top compared with the bottom ofthe industry is extremely narrow.

In contrast, there are two divergent industries in Spain, similar to thesituation found in Australia. The larger, traditional Spanish industry hasevolved its own unique greenhouse structure, which has minimalenvironmental control and is dominantly used for winter production. Thesmaller, newer industry on the other hand, reflects the world’s best standardsin technology and greenhouse design. A heavy Dutch and British influence isdetectable, with many modern operations, in fact, involving directinternational - often Dutch - investment. In total, the greenhouse industry inSpain covers as much as 40000 hectares, though this may be a conservativeestimate. The newer industry possibly accounts for no more than two percentof the total industry at present.

The industry in Canada (in the two provinces I was able to visit) moreclosely spotlights the potential of the Australian industry than anywhere elseI visited. A strong Dutch influence is noticeable though there remains a distinctrange of technological levels throughout the industry unlike the Dutchindustry that varies little between growers. Two key areas of the Ontarioindustry are the Leamington and the Niagara districts, to the south andsoutheast respectively of Toronto. The Leamington area is primarily involvedin the growing of vegetables while the Niagara peninsula is the largestfloricultural production area in Canada. There are approximately 800-1000hectares of greenhouses in Ontario, with around half the area used forvegetable production, half for floriculture. Tomato is the single biggestgreenhouse vegetable crop in Ontario, with over fifty percent of the harvestexported to the USA. On the West Coast of Canada, the British Columbian


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greenhouse vegetable industry is around 300 hectares and floricultureaccounts for a further 100 hectares of structures. Vegetable and floriculturaloperations are mixed throughout the region of Vancouver from the Deltaregion east to Abbotsford. A small proportion of the industry is located onVancouver Island.

A range of greenhouses are used, including glass and plastic cladstructures and the level of technology varies significantly from one end ofthe industry to the other, though this difference does not necessarily correlatewith the profitability of an operation. The average size of floriculturalgreenhouse operations is approximately 1 hectare while vegetable operationsare twice this area.

ORGANIC VEGETABLE PRODUCTION

INTEGRATED DEVELOPMENT

Organic farming is estimated to be growing at 30% a year worldwide inresponse to market forces (Troeth, 2001). Export market demand for certifiedorganic produce, especially vegetables, currently exceeds supply (Kinnear,2000) and in many cases produce attracts premium prices (Fielke, 2001). TheAustralian organic industry is small relative to the conventional foodproduction industry. This trend is reflected in the Tasmanian vegetableindustry where only five, out of approximately 1500 commercial vegetablegrowers are certified organic. Only one organic vegetable grower is producingon a large-scale commercial basis.

Tasmanian packing and exporting companies have increased their interestin organic produce in response to the global trend for increased consumption.The opportunities are considered substantial enough by some to initiate,develop and support a commercial organic vegetable industry in Tasmania.Export markets have considerable appeal due to demand for year roundsupply of fresh organic produce and an average price premium of 23% aboveconventional product.

A scarcity of data on the commercial production of intensively croppedorganic vegetables, combined with market potential, were the primary driversof this four-year project. The result was a partnership between the Departmentof Primary Industries, Water and Environment (DPIWE) and Field FreshTasmania (FFT), with funding from the Rural Industries Research andDevelopment Corporation (RIRDC).

Aims/Objectives :• Test and evaluate, on a commercial scale, organic production

protocols for a range of vegetable crops.• Document case studies assessing the production protocols, cost,

net yields, market premiums and cost effectiveness of intensiveorganic vegetable production.


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• Provide information and training in organic production protocolsfor both existing and prospective organic vegetable growers.

A 10-hectare site, located amidst intensive vegetable productionenterprises on the northwest coast of Tasmania, was selected for the trial.Conversion of the site to a certified organic status was conducted during theproject and was a principle feature of the work. The trial site consisted ofthree paddocks, which were split lengthwise to form six units of approximately1.2 hectares each. A five-year cropping rotation was then overlaid onto thesite plan representing an intensive vegetable production system of four yearscrop and one-year pasture/rest phase. Crops chosen consisted of thoseconsidered relatively easy to grow organically (broad beans, snow peas,carrots) as well as those with the highest market demand but greater difficultyto produce organically (onions, shallots).

Although an initial 5-year rotation was selected as a guide at thebeginning of the trial, this was reviewed prior to each season and adjustmentsmade according to the market information and the previous season’sproduction data.

Production Protocols: Production protocols for the major crops (onionsand carrots) and for test crops (shallots, broad beans and snow peas) wereprogressively developed, adapted and refined throughout the trial forimproved performance.

Carrots and Onions: Inter-row spacing configurations were manipulatedfor greater soil cover and to improve accessibility and effectiveness of weedingmachinery. Planting times for carrots were altered to reduce insect burdenand to meet market requirements. Addition of organic fertilizer and nitrogenbudgeting were incorporated to improve nutritional health of crops. Bedpreparation and pre-emergence weeding (flame) were adjusted for weedmanagement purposes in onions.

Shallots, broad beans and snow peas: A protocol for shallots wasestablished however, bulbs from the first crop were mostly unmarketable dueto a late planting date and a colder than usual season.

A second shallot crop was planted in the subsequent season using theformer season’s protocol.

Planting layout and density of broad beans were manipulated forimproved weed control, airflow and accessibility. Snow peas were deemeduneconomical due to high hand harvesting costs and low yields, and wereploughed in as green manures.

Yield data from the trial was collated and details are presented in thereport. Yields were mostly expressed in terms of net yield (t/ha) of Class Iproduct and pack out (percentage yield of Class I product). The exception iswhere either low total yield or low product quality occurred, in which instanceonly gross values are provided.

Carrots and Onions: With the exception of the 2002 crop yields, the packout


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values for the harvested carrot crops were similar or better than averageconventional yields indicating an overall high quality. The carrot crop yield in2002 was low, primarily due to wet weather and wet soil preventing pre-emergence flame weeding. The yields of organic onions were low compared toconventional yields. A heavy weed burden may have impacted on yield.Cutworm and accidental removal of crop plants with mechanical weedingimplements may have also had a minor effect. A change in planting configurationin 2002 contributed to a further decline in yield during that season.

Shallots, Broad Beans and Snow Peas: The quality of product harvestedfrom shallot crops was considered to be of a suitable market quality andcomparable with conventional crops. However, due to agronomic difficultiesexperienced, it is difficult to draw any meaningful conclusions or viewsrelating to yields and associated factors. Difficulties experienced related to alater than ideal planting time and colder growing conditions which wereincompatible with variety requirements. Harvested seed from the first broadbean crop was retained for subsequent use. Sufficient product from the secondbroad bean crop was harvested specifically for test marketing purposes andas a consequence extensive field data on yields and associated factors wasnot collated. Snowpeas were produced for one season only. Due to the highcosts associated with the harvest and packing of crop, the volume harvestedwas extremely small and not sufficient to produce reliable data for analysis.

Marketing and Economics: Market opportunities were assessed prior tocrop selection and planting.

Produce from the trial was sent internationally to the United Kingdom,Japan and interstate.

Carrots and Onions: Initial market feedback on the first year’s productionof carrots was very positive regarding quality, however all the marketsindicated that premiums for pre-conversion and in-conversion organicproduce are difficult to achieve. Data from the first crop indicated that organiccarrot production could cost $100-$130 a net tonne more than conventionalcarrot crop production.

This poses a difficult financial dilemma for the pre-conversion andconversion periods in the absence of a suitable market premium. Despite lowonion yields, pack-out figures were high indicating excellent onion quality.The majority of the harvested bulbs fitted market specifications and wereexported to the United Kingdom. The bulbs were solid with tight skinspresenting them as ideal for long term storage and shipping. Based on thisexperience they are considered comparable with onions grown usingconventional production practices.

Shallots, Broad Beans and Snow Peas: Shallot bulbs from the first cropwere mostly unmarketable due to late planting date and colder than normalgrowing season. In 2002, FFT planted a shallot crop using the protocolsestablished. Problems occurred when irrigation and rain delayed weeding.


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Due to the small recovery of Class 1 product in the second season the viewwas taken that the volume was too small to justify export. Instead, the productwas marketed in Australia – at higher prices than those achievable in exportmarkets. Commercial samples of broad beans were airfreighted to Japan andthe quality was reported to be of a suitable standard. Difficulties wereexperienced due to the extremely narrow production window, whichprevented a sustainable marketing campaign.

Evaluation was undertaken in Japan on the options of supplying productin complete pod form and individual beans, but both options proved to becommercially non-viable. Test marketing in Australia was undertaken andalthough initial quality feedback was positive, fungal deterioration becameapparent with some product losses experienced by clients. Demand for broadbeans over the production period was limited and clients reported that productdemand was strongest during winter months. Whilst the product wasconsidered to have niche interest, the prices were well below the levelsrequired to make it commercially viable. Snow peas were grown in 2001; thecrop was sown in two plantings for sequential harvest. The hand harvestingcosts for the first planting outweighed the market return. The variety wasdetermined to be unsuitable and achievable prices were extremely low.Although product quality was considered suitable, hand harvest meantproduction was uneconomic.

Weed and Pest Management: Weed control in the absence of herbicideswas the dominant pest management issue in this project. Weed managementwas particularly challenging in the allium crops as they do not form a cropcanopy to assist in competition against weeds. These crops require constantweed control through to harvest.

However, non-herbicide weed management protocols for onion, carrotand broad bean crops were established and are detailed in this report. Theyconsist of a range of well-timed mechanical techniques. Evidence of diseasewas detected in a number of crops grown at the organic trial site. However,whilst crop diseases occurred at the site, they were not considered a majormanagement issue. Copper and sulphate applications were used as the onlyform of fungicide at the site; the mixture is preventative and requires regularapplications. Overall, the effectiveness of the fungicide treatments was good.Poor results were generally viewed as due to poor timing in application.Overall insect pests, like disease, were not considered a major problem at theorganic trial site. However, they were detected in some crops at levels highenough to cause economic damage. Insect pest management included the useof natural pyrethrins.

Agronomic Challenges for Converting to Intensive Organic VegetableProduction: The three principal agronomic challenges identified by the trialwork are:

• Weed Management: Weeds proved to be the greatest pest management


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issue associated with intensive organic vegetable production andwere a significant factor in the final production costs.

• This project indicated the major challenge to improve the economicviability of intensive organic vegetable production was to decreasethe level of hand weeding required.

• Soil Health and Nutrition: Soil structural damage was noted at thesite and was primarily attributed to heavy vehicle use on moistsoil at harvest. In addition, despite legume rotations, availablenitrogen decreased rapidly over the trial period. Improvements insoil organic carbon were identified as essential, while pH levelswere considered satisfactory. Long term soil monitoring at the sitewould be beneficial.

• Skills: An organic producer needs to be highly skilled withadditional and/or different skill sets to conventional farmers. Theproject team believe that many conventional farmers that maydecide to convert would need additional training and skills supportparticularly through the conversion period. Such support is likelyto enhance the success rate of the conversion process and subsequentorganic cropping operation.

CHARACTERISTICS AFFECTING VEGETABLE PRODUCTION

The unique combination of climate, landscape, parent material, and livingorganisms in southwest Florida has greatly influenced the formation of soilsin this area. With time, many of these soils have formed distinguishingcharacteristics, termed diagnostic horizons. These horizons are identified byobserving the soil with depth, such as the side of a pit or a road cut. In turn,these diagnostic horizons are useful for classifying soils and relating theircharacteristics to commercial crop production.

The surface horizon, designated by a capital A, usually appears gray toblack and is almost always of sandy texture. Moving down the soil profileand just beneath the A horizon, a leached zone called the E horizon is oftenfound. Nutrients and fine particles including organic matter are moved bywater from this horizon. The E horizon is usually much lighter in colour thanthe surface horizon, often gray to white.

Located beneath this leached zone, some soils have a distinct brown orblack horizon, called the Bh or spodic horizon. This horizon is composed oforganic matter that is leached down the profile and by both physical andchemical means has been deposited in the lower part of the soil profile. Oftenhigh in aluminum and iron and usually with a low pH, the Bh horizon isalmost always sandy in texture. This horizon impedes water flowing verticallythrough the soil and causes water to accumulate above this horizon. Thiswater accumulation is referred to as a perched water table and is quite beneficial


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for maintaining a constant water table for row crop subsurface irrigation.In some soils, the Bt is another diagnostic horizon that may be found belowthe leaching zone or occasionally with the Bh horizon. This horizon is createdby the deposition of clay particles and is usually mottled gray in colour andsandy or sandy loam in texture. Similar to the Bh horizon, the Bt horizonmay also allow the formation of a perched water table.

Below these diagnostic horizons, substratum may be present. The Chorizon denotes substratum that can be a variety of textures and colours butis usually unconsolidated materials. The R horizon denotes substratum thatis limestone bedrock (not shown).

Using these diagnostic horizons, most of the mineral soils in southwestFlorida can be classified. The USDA-NRCS (Natural Resource ConservationService) has prepared soil survey reports for each county in Florida. Thesedocuments are invaluable for understanding soils used for commercialvegetable operations and contain maps showing the spatial distribution ofsoils in the landscape. While some soils may be better suited than others forvegetable production, soils often occur in associations and complexes, whichdescribe a mixture of soils within the named mapping unit in the surveys.Thus, soil survey maps are considered accurate but not precise, meaning thatthe general management, as well as the chemical and physical characteristicswithin a mapping unit, is accurately described, but any one spot within thelandscape may not be precisely described.

Further complicating precise characterization of any specific landscapepoint is the fact that some of the soil profile layers may be mixed during theconstruction of drainage ditches and beds. Depending upon the constructionof field drainage and vegetable bedding operations, soil material used to createthe bed or excavated to form the drainage ditch may actually contain portionsof the lower horizons. Thus, vegetables may be planted (transplanted) inportions of the subsoil, rather than in the A horizon where most of the nutrientsand organic matter of the original soil are located.

SIGNIFICANCE OF VEGETATIVE PROPAGATION

Rooting in stem cuttings can be important means of vegetativepropagation for afforestation purposes. In arid zones, quick establishment ofplants with ample root systems is a necessity. In arid regions, water in theform of precipitation is available only in the rainy season, and the plantsmust be established in suitable conditions of soil moisture. Therefore, rootedstem cuttings are more useful than seed sowing because rooted cuttings arefar better able to survive in the stressful environment of the desert thandelicate seedlings.

There are various methods of multiplication of mulberry plants. Inmulberry species, the stem cuttings readily form roots. Both grafting and


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layering need time for establishment. Hence, propagation of mulberry throughstem cuttings is preferred. Thimann and Behnke-Rogers showed that therooting of cuttings of many tree species is stimulated by synthetic growthsubstances. Bose has developed easier and better methods of vegetativepropagation by the use of growth substances for ornamental and fruit plants.Bose and Mukherjee used some growth substances to improve rooting incuttings of Legerstroemia indica. Prasad and Dikshit obtained maximum successin rooting with cuttings of essential oil–producing plants treated with growthregulators. Teaotia and Pandey obtained better results in rooting guava stemcuttings with the assistance of growth substances.

FACT ORS AFFECT ING VEGETAT IVE PROPAGAT ION

More than 50% of the land surface of the developing countries is locatedin the arid and semiarid zones. In many of these countries, in which morethan 80% of the population lives with agricultural and animal husbandry, atragic and dangerous imbalance is developing between requirements for andavailable supply of food, fodder, and fuel. Dwindling vegetation cover willadversely affect all facets of rural life in which trees and shrubs generallyserve not only as fuel but also as shade and shelter for man, animal, and crops.In the long term, depletion of the natural vegetation will increase ecologicalfragility and contribute to gradual degradation of the resource base as wellas the natural resources themselves.

A practice common among peasants is migration of cattle to neighboringstates or within the state wherever fodder is available. This large-scalemigration does immense harm to the delicate ecosystem. Animals usually stripall of the plants from the area; this causes poor regeneration and increasedsoil erosion, and more areas become barren. This necessitates the utilizationof saline wastelands for fodder production as crop cultivation is impossiblebecause of the high salt content of the soil. Enumeration of indigenous salinespecies showed that very few plants are palatable and their growth pattern isnot at an acceptable level for fodder production.

Many taxa of the family Chenopodiaceae are indigenous to arid and salineregions of the world. Their ecological amplitude is very high, and variousadaptive features at different levels of the plant life cycle are observed. Manyare shrubs, and they offer a tremendous potential for human benefit in makingthe arid and semiarid lands of the world more productive and useful.

To revegetate the salt-affected soils and secondary salinized soils, plantsthat can survive in arid and saline conditions are needed. Shrubby halophytesof the genus Atriplex are particularly adapted to such conditions. The genusAtriplex includes several haloxeric fodder species very useful in arid zones.The primary driving force of all animals is the need to finding the right kindof food and enough of it. Food is the burning question in animal society,and the whole structure and activities of the community are dependent upon


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questions of food supply. Saline and sodic soils are problems of individuallocalities, and their formation and causes of development must be consideredbefore these soils are put to any economic use. Salt-tolerant plants have beenused as forage in arid saline areas for millennia.

The recognition of the value of certain salt-tolerant shrub grass species isreflected in their incorporation in pasture improvement programmes in manysalt-affected regions throughout the world. However, reproduction, survival,and multiplication under the inhospitable conditions of arid saline areas arebasic needs for any halophytic or glycophytic species. In many halophytes,germination of seeds is usually retarded by high concentrations of salt in thesoil. Germination is the most important stage in the life cycle of any speciesgrowing in an arid saline environment.

Seed germination in saline environments occurs mostly with highprecipitation, when soil salinity levels are usually reduced.

It is also known that when seeds are sown in a saline environment, thereis a decrease in the rate of germination, delaying completion of germination;moreover, there is a water potential below which germination does not occur.In general, it is agreed that salinity affects germination by creating sufficientlylow to inhibit water uptake (osmotic effect) and/or by providing conditionsfor the entry of ions that may be toxic to the embryo. These constraints affectthe different stages of seed germination and seed establishment to varyingdegrees.

Reduction of germination occurs when halophytes are subjected tosalinities above 1% NaCl; increasing salt concentrations also delaygermination. Salinity or sodicity and water stress are the most importantfactors responsible for limiting seed germination and plant growth. Toovercome the present environmental stress of saline areas, plants produce avariety of ecological adaptations. Propagation through vegetative means hasbeen used as a method of multiplication for a number of plant species underarid saline conditions.

Among factors affecting rooting of cuttings, the position of the shoot playsan important role. It is reported that without auxin treatment and withoutleaves, no roots were obtained in cutting of red Hibiscus and Allamendacathartica. Vegetative reproduction substitutes for or at least contributes tothe reproductive potential of many plants. This statement is more applicableto various halophytic species that are restricted to narrow ecological limits,either in the production of disseminules or by their germination. Self-layeringspecies of Atriplex are at an advantage in establishing themselves in salt-affected soil, which they accomplish faster than other species: the growth ofdeveloping roots results in rapid penetration through the upper salty soillayers. Furthermore, roots developing at different nodes are not dependenton a direct supply of water from the soil. Being well supplied with water bythe parent plant, roots can penetrate layers of extreme salinity.


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VEGETATIVE PROPAGATION IN SALINE PLANTS

The distribution of salinity varies spatially, temporally, qualitatively,and quantitatively. In addition, the responses of plants to salt stress varyduring the life cycle of the individual. Phenotype plasticity involving bothmorphological and physiological changes in response to episodic events isan important characteristic associated with the survival of long-lived plantsunder highly stressful environmental conditions. Transient reductions in yieldin response to salinity may be the result of the adaptive reconstruction ofgrowth habits of a plant. The heterogeneity of saline habitats leads toconsiderable genetic differentiation among populations as a result of naturalselection: an all-purpose genotype capable of growing in a wide range of salinehabitats probably does not exist.

The growth and productivity of Atriplex under conditions of low anderratic rainfall are exceptional, and the adaptation of this species to highsalinity makes its introduction very suitable. Agronomic testing, feeding trials,and development of the best agronomic practices are necessary in theevaluation of suitable species for introduction and mass propagation.

Normal vegetation, except for some halophytes, cannot survive on salineand sodic soils. Thus, areas having soils of these types are of limitedagricultural use unless the salinity is quite mild. Increased salinity hasrendered many lands unfit for cultivation. Plant species that are capable ofaccumulating large quantities of sodium in their tissues are the least sensitiveto the presence of salt in the soil. The tolerance of a species to high amountsof absorbed or exchangeable sodium is modified by the pH of the soil and bythe accumulation of CO2. With increasing human and animal populations andthe need for greater crop and fodder production, nonproductive salt-affectedlands may be used to grow nonconventional crops of economic value andalso such food crops as pearl millet. It is desirable to choose species well suitedto saline habitats and to calculate the most economical means of reclamationto make the salt-affected soils productive. The essential ingredients oftechnology for meeting these problems consist of the use of tolerant species,special planting techniques, and aftercare.

Cultivation of salt-affected areas with palatable halophytes is one of themost promising and ecologically safe approaches in the reclamation process.It also helps cattle breeders and farmers to improve a chronically stagnanteconomy. Selection of the most suitable halophytic species for introductioninto saline land needs extensive research. Malcolm and Sen et al. have produceda guide to the selection of salt-tolerant shrubs for forage production fromsaline lands in southwestern Australia and India, respectively. Importantselection parameters include:

1. Growth and survival for a sufficient period in a representativeenvironment


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2. Reproduction by seed or vegetative means3. Acceptable growth form for management use4. Production of biomass of sufficient quantity, quality, and

acceptability to livestock5. Ease of establishment6. Persistence under a profitable management system7. Effectiveness for erosion control, lowering ground water, and

improvement of habitat for wildlifeIn addition, the plant must be evaluated by another set of criteria before

attempting its development on a crop scale.1. Establishment:a. Seed germination percentageb. Vegetative propagationc. Seedling vigour and root establishmentd. Need for supplemental water and nutrition2. Hardiness under crop production densities:a. Insect and disease resistanceb. Intra- and interspecific competition3. Ecological traits:a. Ecotype variability from which to select stock for introductionb. Total genetic plasticity to different ecosystemsMany halophytic species appear to have significant economic potential

for desert agriculture. In addition, the productivity of cultivated halophytesis high. Haloxeric species of the genus Atriplex are widely used as fodder cropsin otherwise unusable saline wastelands in many parts of the world. ManyAtriplex species are promising in the reclamation of the salt-affected lands.Use of salt-affected soils for uncontrolled grazing, subsistence cropping, orintensive fuel gathering results in degradation of the natural vegetation cover.

This process may take decades to reverse, and the land may never bereturned to its original condition. To slow such deterioration, neweconomically useful exotic species can be introduced in these areas. Forage-yielding xerohalophytes such as Atriplex can be suitable candidates for themanagement of saline wastelands because these plants can also be irrigatedwith brackish water. Land reclamation and rehabilitation in arid zones canbe achieved by using salt-tolerant plant species for a number of differentpurposes suited to the local conditions.

Many halophytic species (e.g., Arthrocnemum spp., Nitraria retusa, Salicorniaspp.) are capable of forming adventitious roots on their twigs. This abilityvaries among species and according to the season of the year. Vegetativepropagation is of great advantage in revegetating salt-affected soils. It favorsmore assured establishment in the field than direct seeding or seedlingtransplantation. Rooted stem cuttings of Atriplex are also helpful in raising alarge number of plants with such desired properties as favorable growth


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habits, regeneration capacity, leafiness, and palatability. Vegetativepropagation of desert shrubs is a means of producing genetically identicalindividuals in species whose sexually produced offspring normally exhibithigher variability. Reduced variability of plant materials can increaseexperimental precision, and many genetically identical individuals arenecessary for varietal testing. Reproduction of desirable parentalcharacteristics such as high seed yield would be valuable in the establishmentof seed nurseries. Vegetative propagation is also a method of producingtransplants of species whose seeds do not germinate readily.

VEGETAT IVE PROPAGAT ION OF SALT BUSH (ATRI PLEX SPP.)

A. amnicola Paul G. Wilson (river saltbush or swamp saltbush) shows aremarkable high growth rate under desert conditions. The seedlings can betransplanted in the first week of October and can be irrigated with poor qualitywater. For the first 2–3 months the growth rate is slow, after which fast growthoccurs. Enormous production of side branches during the winter season is avery distinctive feature, and these newly formed branches (stems) are soft,fleshy, and purplish pink in colour. By mid-December plants attain a heightof about 60–70 cm and lateral branches measure about 50–60 cm. Plants mayshow two types of growth patterns: (1) an erect type and (2) a prostratespreading type. Two-year-old plants may cover an area of more than 2–5 m2.These plants grow sideways and cover the ground very rapidly.

Rooted cuttings of Atriplex species are needed to establish a rapidplantation. Some Atriplex species are subdioecious, with at least three genders.Moreover, rooted cuttings can be used to propagate superior individual plantsfor a variety of purposes, including breeding programmes and provision ofsuperior or uniform outplanting stock. Observations made in the field haverevealed that A. amnicola plants have a natural ability to produce rootedcuttings. During the monsoon season, A. amnicola was found to produce nodalroots from the lateral branches wherever they touched the ground. This abilityis of great importance in binding the loose topsoil. It also helps the plant torecover speedily from grazing pressure and enables the plant to spread rapidlyand multiply. Vegetative propagation is much easier in A. amnicola becauseits nodal root formation helps in the production of a large number of rootedcuttings for field planting.

The effects of different growth regulators used on stem cuttings for rootregulation and axillary shoot growth in different seasons.

Indole Acetic Acid (IAA)

Observations regarding the effect of indole acetic acid on root and shootgrowth branch initiation and growth in the rainy season was observed.Interestingly, at almost all concentrations, very large numbers of roots werealso produced on the internodal region.


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Indole acetic acid did not produce much beneficial effect on root andshoot growth; it promoted roots only when administered in lowerconcentrations. In higher concentrations (40 and 50 ppm) during winterand at all concentrations in rainy seasons, root and shoot growth were affectedseverely: there was no root formation. IAA favored root growth only inlower concentrations (10 and 20 ppm) during the winter and summer seasons,respectively. Slight yellowing and drying effects on leaves were seen at higherconcentrations.

Indole Butyric Acid (IBA)

The effect of IBA on rooting is next to that of NAA; that is, IBA promotesroot growth better at lower concentration (30 ppm) than at higher ones andno distinct difference in the growth of axillary branches was observed. Rootgrowth was maximum in winter at 30 ppm and with welldeveloped secondaryroots. Very poor growth of roots and no initiation of axillary branches wereobserved in plants treated with IBA in summer.

Field Transfer and Establishment of Rooted Cuttings

The effect of growth regulators on root and shoot growth was observedby growing the cuttings in polyethylene bags for 35 days after treatment. It isclear from the results that root growth was maximum at the higherconcentration (20 ppm) of NAA, followed by IBA (10 ppm), and the leastgrowth was obtained with IAA (10 ppm) after 35 days. In the control set, theroots were very much shorter than in the treated cuttings. The maximumdevelopment of roots with profuse secondary roots was observed with NAAand IBA. Whereas IAA suppressed the growth of roots and axillary branchesduring summer.

NAA and IBA enhanced the growth of axillary branches to a maximum,but the number and the length of the roots were diminished in comparisonwith NAA. The maximum number of axillary branches was observed in winterand rainy seasons, the least in summer. The propagation of stem cuttings ofseveral saltbush species and a few species from other salt desert shrub generawas studied by Nord and Goodin, Wieland et al., Ellern, and Wiesner andJohnson. Although Nord and Goodin and Ellern observed a general trend forbetter rooting of saltbush (Atriplex) species in spring than in fall, no datawere available for summer and winter. Nord and Goodin noted better rootingof green stem tips than ripe wood cuttings, but Ellern failed to find anydifference in rooting of soft, green cuttings and young woody stem cuttings.

Nanda et al. used IAA, IBA, and NAA to enhance the rooting responseof stem cuttings of forest trees and investigated the possibility that evenseasonal changes in the effectiveness of different auxins are governed bymorphophysiological factors. Auxins enhanced the rooting of stem cuttingsof Populus nigra and Hibiscus rosa-sinensis even during December–February,


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but these hormones failed to cause rooting in Ficus infectoria cuttings duringthe same period. It was observed that auxins enhanced the rooting more inwinter, followed by the rainy season, and least in summer.

Indole acetic acid has been one of the most commonly used auxins, butdifferent workers have obtained varying results. Chatterjee found thatPogostemon potehouli, an essential oil–yielding plant, responded more favorablyto IAA than other auxins. Shanmugavelu also obtained the maximumpercentage of rooting in cuttings of certain shrubby plants with IAA. On theother hand, NAA gave favorable results in the induction of roots in cuttingsof Levendula, Ficus infectoria, and Hibiscus rosa-sinensis. The experimental resultsof our study showed that a large number of roots were produced at lowerconcentrations of NAA, IAA, and IBA.

A number of saltbush species may be established from cuttings, includingA, amnicola, A. nummularia, A. canescens, A. halimus, A. lentiformis, A. paludosa,and A. polycarpa. The cuttings should be taken at the peak of spring growthor in the autumn in a Mediterranean climate. The wood should be about 6mm thick and 250 mm long, taken from young stems between two leaf axils.A rooting hormone (e.g., IBA) may be applied to encourage root growth beforeapproximately half the stem is covered with a moist, sandy soil. The cuttingsshould root within 6 weeks and should be ready for transplanting in 10 weeks.In our study, IBA also enhanced the rooting in A. amnicola. According toRichardson et al., fourwing saltbush cuttings could be rooted best in thesummer, but A. amnicola rooted best in winter, followed by the rainy seasonand summer. According to Sharma and Sen and Rajput and Sen, respectively,winter is most suitable for the vegetative propagation of Tamarix and Atriplex.The present results also support these views.

The results of field experiments showed that NAA is more effective thanIBA and IAA. The increased appearance of new leaves with an increase in thepercentage of rooting also points to better rooting possibilities, with theemergence of more new leaves on the cuttings. The greater number of rootsper cutting and the greater number of leaves may also help the cuttings tosurvive when sown in natural conditions.

VEGETATIVE PROPAGATION OF MULBERRY (MORUS SPP.)

Since the dawn of agriculture, one of the principal aims of human beingshas been the control and promotion of plant growth to satisfy human needs.These two important aspects of people’s work with plants in the struggle toincrease production are by no means synonymous. Humans soon realized thatlush green growth does not always produce the best crop in the form of fruitand seeds, and hence they were forced to evolve such well-known culturalmethods as pruning, balanced manuring, and use of mineral fertilizers toregulate the nature and luxuriance of plant growth. The naturally occurring


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(endogenous) growth substances are commonly known as plant hormones,while the synthetic ones are called growth regulators. A plant hormone(synonym: phytochrome) is an organic compound synthesized in one part ofa plant and translocated to another part, where at very low concentrations itcauses a physiological response. Plant hormones are identified as promoters(auxin, gibberellin, and cytokinin), inhibitors (abscisic acid, xanthoxin, andviolaxanthin), and ethylene and other hypothetical growth substances(florigen, death hormone, etc.). They usually exist in plants and crops at aconcentration lower than 1 M; above this, they are generally consideredsupraoptimal.

Mulberry is propagated either through seeds or vegetatively. The latteris the more common method of propagation because of such advantages asmaintenance of particular properties of the plant, relative speed in raisingsaplings in large numbers for plantation, adaptability to a particular habitat,and abilities to develop resistance to pests and diseases and to modify thegrowth of plants. Propagation through seeds has reached certain limitations.For example, triploid plants, which do not produce viable seeds, cannot bepropagated. It is not possible to reproduce true to the type from a seed ofbiparental origin.

Mulberry is a highly heterozygous plant that is open for cross-fertilization.Therefore, the seeds that are formed through open pollination are naturalhybrids. Seedling populations from such seeds provide wider chances forselection of superior types whose characteristics are perpetuated throughvegetative propagation. Generally, the population thus obtained is a mixtureof several clones. Each clone is heterozygous although homogeneous, and thesame genotype is maintained because propagation is vegetative, Interclonalvariations are due to heredity. Depending on climatic and soil conditions,different countries follow different modes of vegetative propagation. Hamadadescribed the methods used in Japan, which include (1) bark grafting(Fukurotsugi), (2) veneer grafting (Kiritsugi), (3) simple layers (Magedori),(4) continuous layers (Shumokudori), and (5) division (Shirodasmi), hardwoodcuttings (Kojyosashiki), and softwood cuttings (Shinshosashiki), Generally,grafting is used in places where the temperature is 6°C in March and morethan 25°C in July, with rainfall of 175 mm. Shirodasmi cottage is popular inplaces having temperatures less than 4°C in March and less than 25°C in Julywith rainfall lower than 175 mm. Propagation through hardwood andsoftwood cuttings is common in the northern districts and the southernregion, respectively, of Japan. In Italy, rooted grafting is a popular method ofmultiplying Japanese mulberry varieties.

In India, the most common method of propagating mulberry is throughcuttings in multivoltine regions (e.g., Karnataka and West Bengal). Exoticvarieties that are not established by cuttings are propagated through rootgrafts. Many of the indigenous varieties and well-acclimatized exotic varieties


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are propagated through cuttings. Bud grafting (budding) is used only whenscion material is scarce. Whenever a large number of mulberry plants mustbe obtained in a shorter time than would be possible if they were started as acutting, the method of layering is used. Layering allows the grower to fill inthe gaps formed as a result of the failure to sprout of certain cuttings plantedin pits of established plantations.

In univoltine areas (e.g., Kashmir), the mulberry is propagated throughseedlings and the exotic varieties through root grafts. In India, the field-scalepropagation through cuttings of Japanese varieties of mulberry is still aproblem.

Propagation through seeds is used mainly to bring about a variedpopulation for the purpose of selection and hybridization. Because mulberryflowers are open for cross-pollination, the seeds thus collected serve mainlyas sources of stock material for grafting. In general, a deficiency of hormonemust be created experimentally (as by removing young leaves or using ahormone-deficient mutant) to show that adding a hormone has an effect. Inthis respect, the Mitscherlich law of diminishing return can be modified asfollows: the increase in plant response produced by a unit increment of adeficient (limiting) hormone is proportional to the decrement of that hormonefrom the maximum.

Mulberry varieties that do not ordinarily produce roots from a cuttingare induced to root with application of the requisite quantity of root hormones.The following chemicals are generally used, but their efficiency varies fromspecies to species and from variety to variety: (1) IAA, (2) IBA, and (3) NAA.The objective of using growth regulators is to increase the percentage ofcuttings that form roots, hasten root initiation, and increase the number ofroots per cutting. IBA and NAA have proved to be better in producing rootsthan other growth regulators. The water requirement of mulberry does notdiffer greatly from species to species or from variety to variety. The plantmust be capable of absorbing water from soils of low moisture regimes.Generally resistant plants should have well-developed root systems,hydrophilic colloids to absorb and hold water by imbibition, and adaptationsto facilitate the lowering of transpiration. In this regard, certain Japanesevarieties have a thick cuticle, sometimes a two-layered epidermis, a palisadeparenchyma, and other beneficial characteristics.

Although many tropical species root profusely through cuttings, certaintemperate varieties do not ordinarily produce roots. Root induction has beensuccessfully achieved in the latter varieties by the (artificial) application ofthe requisite quantity of root hormones. However, the efficacy of thesubstances varies from species to species and from variety to variety.

Development of the root primordium depends on the relative amount ofnatural auxin present in the plant. Varieties that do not root apparently containless auxin. The growth regulators act like auxins when applied in small


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quantities and move upward in mass translocation through the xylem whenthe bases of the cuttings are soaked in their solutions. The objective oftreatment is to increase the percentage of cuttings that form roots, hasten rootinitiation, and increase the number of roots per cutting. Indole butyric acidand naphthalene acetic acid appear to be better at producing roots than otheragents. The chemicals may be applied by various methods, including directapplication of a powder, soaking the cuttings in dilute solutions, dipping thecuttings in concentrated solutions, and application as a paste in lanolin.

The action of many gibberellic acids (GAs) is similar to that of IAA,including elongation, promotion of cambial activity, induction ofparthenocarpy, and stimulation of nucleic acid and protein synthesis. TheGA3s vary greatly in their biological activity, and GA5 and GA7 are consideredto have the widest range. In ferns, algae, and fungi, GA3s have also beenshown to influence growth and development.

For the vegetative propagation experiments, mulberry cuttings werecollected from both cultivated and wild varieties at Jodhpur (site Chopasni).Growth regulators used for root initiation in cuttings were NAA, IAA, IBA,and GA. Shoots of thick branches with well-developed buds were used forrooting experiments. Cuttings taken from parts with a high carbohydratecontent have been reported to root more readily and profusely than cuttingsselected from parts rich in nitrogen. Portions of the shoot that were too tenderat the top and overmature at the base were rejected. Cuttings taken from youngbranches sprouted rapidly and profusely as compared with those taken fromold parts. Cuttings of 7 to 10 cm usually of pencil thickness with three to fourwell-developed buds were prepared from the central portion of the clone witha slanting cut.

Also, the total leaves generally increased, together with the number ofinflorescences. Increasing concentrations of hormones tended to decrease thevalues. Slightly higher values of these parameters were observed with 10 ppmthan with 20 ppm IAA. Of the two auxins, IAA was more effective than NAA.The case of NAA, a lower concentration is more effective than a higher one.From the observations of the rooting behaviour in a wild variety of mulberry,we see that the lower concentration of IAA is more effective than the higherone. The maximum number of sprouting buds was 11; afterward the valuesremained constant. However, in the case of NAA, 20 ppm was more effectivethan 10 ppm. Comparatively, IAA was more effective than NAA and highervalues were observed in the wild than in the cultivated variety.

Cuttings were immersed in different concentrations of growth regulatorsfor 24 hr. During treatment, cuttings were kept inside the growth room. Afterthis treatment, cuttings were washed in distilled water and individuallytransferred to test tubes filled with water. Three cuttings were used for eachset, and each set was repeated three times for confirmation. The observationswere recorded after a definite interval of time. Measurements of bud sprouting,


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number of leaves, inflorescence, and root initiation were observed in thecultivated variety. The lower concentration (10 ppm) of IAA led to a betterresponse than the higher one (20 ppm). At 10 ppm the bud sprouting was100%, whereas with 20 ppm it diminished to 4. Leaf initiation and inflorescencefollowed the same trend as the bud sprouting, being 8 and 11, respectively,in 10 ppm, and 8 and 6, respectively, in 20 ppm.

Similar results were obtained in NAA, with 100% bud sprouting in 10ppm, slightly more than in IAA, being 5. Leaf initiation and inflorescence werealso higher in 10 ppm compared with 20 ppm, being 9, 9, 8, and 5, respectively.

IAA again showed a beneficial effect at the lower concentration (10 ppm)as compared with the higher (20 ppm), producing 7 and 4 buds, respectively.Leaf initiation increased from 7 to 10 with increasing concentration, but theinflorescence did not show any change.

The results with NAA showed effects similar to those with IAA. At 10ppm, 8 buds sprouted out of 8 buds, whereas at 20 ppm the figures were 4out of 7 buds. Leaf initiation showed a better response at the lowerconcentration than at the higher one, and a similar trend was also shown forinflorescence.

Growth means an irreversible increase in the weight, area, or length of aplant or a particular tissue or organ of a plant, while development denotesthe changing pattern of organization as growth progresses. Control over plantgrowth by the regulated exogenous supply of chemical substances may occurin different ways. It has become clear that total control of plants is vested notin a single hormonal type; rather, control is shared by a group of severalspecifically defined auxins, gibberellins, ethylene, and certain naturallyoccurring inhibitors such as phenols and abscisic acid. Thus, the plant growthregulators provide a very helpful tool for controlling physiological processesin plants.

NAA was found to be better than IAA in rooting by Jauhari and Rehmanin cuttings of sweet lime. It responded favorably on induction of roots in stemcuttings of many plants. In the present study IAA was found to be moreeffective than NAA.

Stem cuttings of Ipomoea pes-caprae and species of Morus showed a largenumber of roots and buds in the higher concentration but with maximumsuppression of growth, whereas lower concentrations resulted in onlyimprovement in the growth of roots. In our investigation also, the highervalues were observed with lower concentrations of the growth regulators.Under favorable environmental conditions, during the period of rootdevelopment, a callus tissue develops at the basal end of a cutting: an irregularmass of parenchyma cells in various stages of lignification. Callus growtharises from cells and adjacent phloem, although various cortical and medullarcells also contribute. Because root development and callus formation occursimultaneously, it is believed that the formation of callus is essential for root


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development. In reality, these two are entirely different phenomena. Sometimesroots develop even without callus from the nodes. Callus formation issometimes beneficial in varieties that are slow to root because it provides aprotective layer, preventing the cutting from becoming desiccated anddecayed. Sometimes the callus interferes with the absorption of water by thecutting. In our investigations, rooting did not start, instead, callus formationwas observed after 1 week of treatment. The callus was creamy white andhad a granular texture.

The rate of sprouting of vegetative buds is of primary consideration inintroducing a variety or species in an area. Mulberry varieties grown in Mysoreand West Bengal sprout throughout the year, facilitating the attempts ofsericulturists to rear the silkworms year-round. The axillary buds vary in size,shape, and position from variety to variety. Thus the rooted stem cuttingsare more useful than seed sowing because the survival of a rooted cutting isfar better than that of the delicate seedlings in the stressful environment ofthe desert.

SEED ST ORAGE IN CERTAIN FRUIT CROPS

Mango

Mango seeds are protected by hard stony endocarp. Seed is ex-albuminous having two fleshy cotyledons with testa and tegmen representedby two papery layers. Polyembryony is observed in certain cultivars. Seedexhibits recalcitrant type of storage behaviour wherein seed loses the viabilityon drying after extraction and undried seeds cannot be preserved long at lowtemperatures.

Reduction of seed moisture to below 25% in Alphonso and 32% inTotapuri lowered the germination percentage and seedling vigour (Doijode1990). Patil et al. (1986) obtained 40% of germination in Alphonso stones after90 days of storage at 25°C in polyethylene bags with charcoal powder. Itdeclined from 75 to 12% after 60 days when stored in open while those storedin polyethylene bags at 8°C did not germinate at all.

The moist storage appears to be successful for preservation of recalcitrantseeds. Here seeds are imbibed with either germination inhibitor or fungicidesfor preventing germination and pathogens during moist storage. Seedtreatment with 1% 8-hydroxy quinoline sulphate and storage at 15°C couldpreserve the seed viability for one year (Doijode 1995).

Citrus

Citrus seeds are either mono- or polyembryonic in nature. They arelargely Utilized for raising rootstocks as well as in breeding programme.Lime (Citrus aurantifolia) seeds are small, oval and polyembryonic with whitecotyledons. Lemon (Citrus limon) seeds are ovoid and polyembryonic with10-15% nucellar embryos and white cotyledons.


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Sweet orange (Citrus sinensis) seeds are obovoid, polyembryonic withwhite embryos. Mandarin (Citrus reticulata) seeds are small polyembryonicwith green embryos. Pummelo (Citrus grandis) seeds are large ridgedyellowish and monoembryonic. Grape fruit (Citrus parodisi) seeds are white,polyembryonic with white cotyledons.

Seeds of many Citrus species are viable for a short period under ambientconditions. The seeds belong to orthodox group and/or show intermediatestorage behaviour and require special procedure for preservation. Seed storagein moisture proof containers at low temperature checks the deterioration byreducing metabolism. Seed storage with calcium chloride in polyethylene bagsat 8°C resulted in 100% viability in Citrus karna and rusk citrange and 84% inCitrus jambhiri and Citrus limonia after 150 days (Krishna and Shankar 1974).

Acid lime seeds were successfully stored for 10 years at 5 and -20°C. Grapefruit seeds retained viability for 3 months when stored with charcoal at roomtemperature and for 4 months at 5-8°C (Chacko and Singh 1968). In Poncirustrifoliata and Citrus grandis, germination was the highest after 80 days inseeds stored in polyethylene bags at 4.4°C and 56-58% RH (Mallareddy andSharma 1983).

Seeds could be stored in fruit itself for short term preservation. Fruits ofsome lemon cultivars were successfully preserved for 40 days at ambienttemperature and for 60 days at 5°C (Doijode 1984). Bajpai et al. (1963) alsoreported that seed storage in whole fruit of kagzi lime and sweet orange isbetter than in polyethylene bags.

Rambutan

Seeds are difficult to store under normal conditions (Ellis 1984) and atroom temperature they lose their viability within a matter of days. They canbe stored for a few weeks in moist saw dust or charcoal to which some ariljuice has been added at 21-28°C.

Jackfruit

Seeds are large oblong about 3 x 2 cm in size having thick gelatinousyellow covering and belong to recalcitrant group. Seeds remained viable for15 days and gave 40% germination after 30 days of storage.

Litchi

Litchi seeds are dark brown, covered with white fleshy, juicy andtranslucent aril. Seeds are recalcitrant and should not be allowed to dry. Whensown immediately after extraction, their germination was 100% which reducedjust after one day storage in water and it was 75% on the seventh day and30% on 15th day after storage. Seeds stored in moisture proof containerssprouted within 15 days and those stored for 10 days in polyethylene bagsshowed 50.7% germination. However, seeds can be preserved in fruit for


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short periods. Seed viability was preserved for 24 days by storing fruits insealed polyethylene bags after treatment with benomyl (0.05%) and 6% waxemulsion.

Mangosteen

Seeds are recalcitrant and lose their viability rather quickly, especiallywhen the thin membrane around the seed is damaged or when seed is placedin ambient or cool atmosphere. Storage of seeds in charcoal or moss at roomtemperature retains the viability for a few months.

Conclusions

Seeds of several tropical fruit crops show recalcitrant storage behaviourand they do not withstand drying or are able to keep alive at low temperatures.Thus, they are difficult to store for longer period. In this context, more researchis needed for extending storage life. However, it is desirable to preserve thegermplasm in field as fruit repository. To supplement the conservationprocess, wherever, as far as possible seeds could be conserved by use ofavailable techniques like moist storage, etc., for certain period.

GERMPLASM OF MANGO

Mango is one of the most important fruit crops in India. It has been incultivation for almost last five thousand years. Apart from India, mango isalso an important crop in the Philippines, Indonesia, Thailand, Myanmar,Malaysia, Sri Lanka, U.A.E., South-East Africa, South Africa, U.S.A., Mexico,West Indies, Brazil and tropical Australia. All the cultivated Indian mangoesbelong to the single species Mangifera indica L. The geographical distribution,phytogenetic trend, pollen morphology, chromosome number, cytogeneticaland breeding behaviour indicate that the highest concentration of species ofMangifera is found in Malayan Peninsula followed by Sunda Islands and theEastern Peninsula comprising Myanmar, Thailand and Indo-China.

Occurrence of wild species like M. sylvatica and M. caloneura in Myanmar,Assam and northeastern India and evidence of fossil leaf impression of M.pentandra which looks similar to M. indica having edible fruits indicate thatmango originated in this region. In India, more than thousand varieties ofmango are available and these have arisen mainly as a result of openpollination.

It is to be admitted that most of the varieties lack in one or the othercharacter. As opined by Naik et al. (1958), this very diversity has tended tolimit commercial production of fruits of standard quality in India. In the recentpast, efforts were made to exploit natural variability and breed new varietiesfor different purposes. So there has been a need to prevent the loss of varieties,and to conserve and use them in the breeding programme. Apart from


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intervarietal breeding programmes, progress has been made with regard toidentifying the location of wild species of Mangifera and their utilization inbreeding.

Collection and Conservation

Mango in India has a long history of domestication and cultivation. Therich varietal wealth, however, has not been collected at one place. Hence, thereis erosion of the genepool owing to deforestation, urbanisation andindustrialization. Systematic attempts to conserve the genepool have beenmade in the past few decades and more than 1266 varieties were collected invarious field genebanks.

In-situ Conservation

The species of Mangifera occur mainly as a complex biotic community intropical humid forests, subtropical rain forests and dry forests/woodlands ofIndo-Malayan biogeographic realm. For in situ conservation, the hilly regionsof east Orissa, and forests bordering Myanmar in Manipur valley have beenidentified.

Ex-situ Conservation

Most of the important commercial varieties grown in India as statedearlier have arisen due to natural cross pollination and selection. Germplasmcollections have been made in the past. Although, substantial diversity ofcultivated M. indica is in the field genebank, this does not contain wild species.Germplasm collections at many centres are duplicated and it has been noticedthat varieties belonging to one region behave differently in other regions.Yadav and Singh (1985) opined that south and north Indian varieties belongto two different ecotypes of M. indica. Mustaffa (1993) confirmed the sameby isozyme analysis. Hence, diverse collection has become a necessity to getactual performance. The major germplasm collection centres are listed.

Conservation in Vitro

One of the main constraints in the maintenance of mango in fieldgenebank has been that it requires large area and funds. In this regard, invitro conservation holds promise. However, in mango, owing to the problemof regeneration of tissue, so far no success has been obtained. Iyer andSubramanyam (1989) have suggested pollen storage of important mangovarieties. This will also help in speeding up the hybridization programme.

Utilization

Almost all the commercial cultivars belong to M. indica. However, a fewcommercial cultivars of South-East Asia belong to other species, such as M.altissima, M. caesia, M. foetida, M. griffithii, M. odorata, M. pentandra, M.


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sylvatica, M. zeylanica, M. laurina, M. lagenifera, M. cochinchinensis, etc.For the improvement of mango, some of the wild species could be of great

help, Iyer (1991) suggested that Mangifera species useful for crop improvementfall into two categories: (i) species having edible fruits with other desirablecharacters, and (ii) species that could act as gene donors for specificimprovement like resistant to pests and diseases. If basic information likecrossability become available then interspecific hybridization in mango canbecome a reality.

CONSTRAINTS IN DECIDUOUS FRUIT PRODUCTION

Large number of old orchards (more than 30 years old) are showingdecline in terms of growth and fruit yield. Such old trees do not produceadequate extension growth. Large scale replanting is therefore needed.

Delicious group of cultivars constitute the major share (about 83% in H.P.)of apple production in the country. These cultivars are self unfruitful and needcross pollination to ensure good fruit set. Interplanting pollinizer cultivars(Golden Delicious, Jonathan, Red Gold, Lord Lambourne etc.) in theproportion of 25 to 33 percent is necessary for good fruit set, and choice ofwrong pollinizers and their inadequacy in number often result to lowproductivity.

In many countries, Delicious group has been replaced or is in the processof replacement with more promising cultivars. The need for injecting newblood into the apple industry through spread of new cultivars (spur types,colour mutants, strains of Gala, Red Fuji; scab resistant cultivars, bud sportselections of Royal Delicious, and some of the promising hybrids) is urgentlyfelt. Some of the spur type and coloured mutants are already popular withfarmers and high density planting has also caught the imagination ofdevelopmental departments and agencies both in H.P. and J&K. The researchsystem has already identified Early, Mid and Late cultivars for different agro-climatic regions.

The low chilling cultivars of stone fruits have also covered large tracts ofthe sub-tropical plains of Punjab, U.P and H.P. For the hills, promisingcultivars identified need further spread.

Generally, apple is grown in marginal land and fertilizers are not appliedaccording to the requirements of the trees. The water and fertilizer useefficiency is generally poor. Also, spring frost and hailstorms are adverseweather parameters leading to low productivity. Research results have shownthat through proper orchard management practices (soil and waterconservation and fertilizer application) the fruit yield can be doubled in theexisting orchards. The adoption of improved production technologydeveloped by the research system can bring visible and perceptible changesin the temperate fruit industry in India. Technologies like use of clonal


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rootstocks, introduction of renewal pruning techniques and micro nutrientapplications have not been transferred and adopted at a satisfactory level.Apple scab disease has been the major plant protection problem in apple inJ&K and H.P, whilst U.P hills are comparatively free from the disease. Applescab forecasting system developed and the chemical control scheduleprescribed have helped in reducing loss due to apple scab to a considerableextent. Apple growers are adopting the prescribed schedule of chemical spraysto control the disease. For checking entries of diseased material in the freeareas of U.P. and North-Eastern Hills, strict quarantine and selection of elitedisease-free mother plants are very essential.

Often it is not followed strictly. Some of the virus diseases have also beenreported in apple for which biological and serological indexing/detectionprocedures have been developed. Limited quantity of virus-free budwood isalso being supplied. Extreme care is now required to be taken to multiplyquality planting material (in apple alone approximately 2 million plants/year)for establishing new plantations.

Most of the orchardists still sell their crop at flowering to contractors asthere is no well organized marketing system. Transportation in the hills itselfis problematic. Post-harvest management problems originating from poorharvesting (strip picking) and improper packing system (non CFB boxes) andlack of proper pre-cooling and cold storage facilities result in huge (25-30%)loss of fruits.

Capacity of the processing sector is also inadequate. Productdiversification, value addition and market infrastructure development wouldrequire very substantial investment. The existing processing units are quiteold and they require modernization for which substantial investment isrequired. CA storage trials have shown good promise. Its extension in largergrowing areas is needed. Technology for storage of apple is now known, as aresult of which apple is now available throughout the year.

GOVERNM ENT POLICIES AND PLANS

Research on pome and stone fruits is conducted mainly by three StateAgricultural Universities, namely: (a) Sher-e-Kashmir University forAgriculture Science & Technology, J&K; (b) Y.S. Parmar University forHorticulture and Forestry, H.P.; and c) G.B. Pant University for Agriculture& Technology, U.P. A good number of research stations of these Universitieslocated in major pome and stone fruit growing belts are engaged in temperatefruit research.

The Indian Council of Agricultural Research (ICAR) through All IndiaCoordinated Research Projects on Fruits and Post-harvest Technology andanother Network project on Apple Scab disease has further strengthened theresearch activities in deciduous fruits.

A few long established temperate fruit research stations namely at


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Shalimar Bagh in J&K, at Mashoobra in H.P. and at Chaubatia in U.P. hillshave made commendable progress in temperate fruits. Both StateGovernments and the ICAR provide financial support to strengthen fruitresearch in these Universities. A large number of ad-hoc research projects onpome and stone fruits funded by ICAR are also generating good informationon these crops.

During the 8th Government Developmental Plan (1992-1997) the ICARestablished a Central Institute for Temperate Horticulture (CITH) with itsheadquarters at Srinagar in the J&K State, with a regional station atMukteshwar in the U.P. Hills. Both these research stations will workexclusively on temperate fruit crops. This new Institute will receive majorsupport during the 9th Plan period (1997-2001). In the North-Eastern Hillsregion, the ICAR Research Complex for NEH Region with its headquarters inMeghalaya State and regional units in each of the 5 other States are engagedin fruit research.

On the developmental side the State governments are engaged in nurseryproduction of quality planting material. For example, in H.P. alone currentlythere are 600 nurseries in private and public sector producing and distributingmore than 0.8 million plants of apple alone, every year. There are ambitiousprogrammes in all the States to further expand/replant with new improvedcultivars. Apple scab disease control and post-harvest processing sectors aregetting focused attention in Government developmental plans.

The Directorate of Marketing and Inspection of the Government of Indiahas framed grade standards for apple, plum and William pear. Theorganizations like National Horticultural Board (NHB), National CooperativeDevelopment Corporation (NCDC), Agricultural and Processed Food ProductsExport Development Authority (APEDA) etc., are providing incentives totraders and exporters to improve their infrastructural facilities like gradingand packaging centres, refrigerated transport, setting up of pre-cooling, coldstorage, auction platforms etc. The NCDC is undertaking procurement andmarketing of apple on a limited scale. The NHB has set up a market informationservice for the benefit of growers.

Deciduous fruits, covering pome and stone fruits contribute significantlyto the horticulture economy of India. Apple production dominates the sceneand systematic cultivation and marketing of apple can change the ruraleconomy in the hills of North-Western India.

New vision and concerted efforts are required for change in variety mix,supply of quality planting material from elite clones on indexed clonalrootstocks. High density planting, water management including micro-irrigation, integrated plant nutrient management and IPM strategy for plantprotection are some of the areas which need greater R&D focus. Adoption ofpost-harvest management practices and infrastructure development forgrading, packaging, pre-cooling and storage of the produce needs focused


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developmental attention. Value addition and export promotion, particularlyof apple are drawing due attention of the developmental agencies in India.

FRUIT CULTURE

Introduction: The Cashewnut (Anacardium occidentale L.) is one of theimportant nut tree grown in the tropical world. This fruit tree was introductedinto Malbar coast of India in 16th century by Portuguese. It is the native ofBrazil. It is grown mostly on West Coast area of Maharashtra, Goa, Karnataka,Kerala and Tamil Nadu.

Importance: The dry nuts - Kernels are of high nutritive value and alsorich in protein, carbohydrates, minerals like calcium, phosphorus and iron.This has a great export value and is considered as one of the importanthorticultural crop in India.

Climate: The Cashew requires a minimum rainfall of 60 cm per annum,but can stand extremes of rainfall from 20 cm to 400 cm. If there is sufficientwater supply, it can withstand a long period of dry spell and low humidity.The Cashew is a sun loving tree and does not tolerate excessive shade, also itdoes not favour very high temperatures above 45 deg cent. During the fruitset and development. Heavy rains and cloudy weather during floweringadversely affect the yield.

Soil: The Cashew is cultivated on a wide variety of soils. It is considereda crop of marginal land and is recommended for slopy and light soils. Thebest soils for better production are deep, friable, well drained and without ahard pan upto 2/3 m in depth.

The Cashew is mainly grown on Laterite, red and coastal sands inIndia.

Varieties: The following are the important varieties of Cashew grown indifferent parts of the country.

i. Vengurla 1ii. Vengurla 2iii. Vengurla 3iv. Vengurla 4v. Vengurla 5vi. Vengurla 6vii. Bhubaneshwarviii. Kanakaix. Dhanax. SelectionPropagation: The cashew is grown by the following methods:i. Seed Propagation: It is the oldest and cheapest method of propagation.

It is also used to raise the plants for the purpose of grafting


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ii. Layering this method is more successful in coastal and more humidareas

iii. Soft Wood Grafting: This is followed both in the nursery as well asin the field of in-situ. For this purpose, veener grafting is done

iv. Top-working: This method is used not for propagation but forconverting inferior free into desirable one

Planting and Season: Normally cashew grafts are planted at the spacingof 7.0 x 7.0 or 7.5 x 7.5 or 8.0 x 8.0 m on plain land or on desirable contours onslopy lands. After marking, the pits of 60x60x60 cm are dug and filled with acompost,top soil, single super phosphate and karnaj cake. This is to be wellbefore the monsoon starts. Planting should be done during June-July i.e. inthe beginning of monsoon.

Interculturing:i. Removal of weeds is done once twiceii. Intercrops are planted in interspaceiii. Some perenial forest plants and/or some seasonal crops can be taken

as per the local need and situationCare of young orchard:i. Gap filling for the missing plantsii. Removal of outgrowth on stocks in case of grafted plantsiii. Staking with bamboosiv. Cover croppingv. Providing protective irrigation during first few summers. These are

some of the points for young plantationsSpecial Horticultural practices:i. Pruning of dead and dried shoots alongwith crisscross branches

and water shootsii. Pruning of leader shoots in June followed by 2% KNO3 sprayiii. Spraying with 10 ppm NAA twice during flowering for increasing

fruit set and minimizing flower and fruit dropIrrigation: The cashew is mostly grown as the rainfed crop and requires

no irrigation in the high rainfall areas. However, if the rainfall is low, thecashew responses well to irrigation water at the time of fruit set upto fulldevelopment stage of nuts. Irrigation should not be given before or at thetime of flowering, as it is likely to promote vegetative growth.

Nutrition: To improve the growth and yield the cashew trees should bemanured and fertilized with bio-fertilizers like biomeal and NpK 500,200, 200gm per tree per year. Spraying with ultrazyme and 8:12:24:4 NPKmg twice,during fruit development is useful to increase size and yield of nuts.

Plant Protection: The crop particularly blossom and fruits should beprotected against Tea Mosquito, Stem and root borer is also an important pest.Leaf minor, Leaf and blossom webber, Flower thrips are the common pests inneglected orchards.


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Inflorescence blight, pink disease, and anthrac nose are some diseasesfound on cashew. Clean cultivation, pruning, better aeration and preventivemeasures should be adopted besides occassional sprays of selected pesticidesand fungicides.

Harvesting and Yield: The Cashew comes to its full bearing stage at theage of 10th year and continuous to give yield further for 30-40 years. Usuallythe nuts are collected after they fall off from the tree. They are separated fromapples and dried for 2/3 days to reduce the moisture. Regarding yield thereis a wide variation and differences of opinions. However, the desirable varietyat good management yields 50 kg of raw nuts.

Post Harvest Handling: The processing of raw nuts involves roasting,shelling, drying, peeling, grading and packing `A' grade nuts are always indemand from the outside markets and fetch a good price. A Fenny like drinksare prepared from the apples.

THE CASHEWNUT

The Cashewnut (Anacardium occidentale L.) is one of the importantnut tree grown in the tropical world. This fruit tree was introducted intoMalbar coast of India in 16th century by Portuguese. It is the native of Brazil.It is grown mostly on West Coast area of Maharashtra, Goa, Karnataka,Kerala and Tamil Nadu.

Importance: The dry nuts - Kernels are of high nutritive value and alsorich in protein, carbohydrates, minerals like calcium, phosphorus and iron.This has a great export value and is considered as one of the importanthorticultural crop in India.

Climate: The Cashew requires a minimum rainfall of 60 cm per annum,but can stand extremes of rainfall from 20 cm to 400 cm. If there is sufficientwater supply, it can withstand a long period of dry spell and low humidity.

The Cashew is a sun loving tree and does not tolerate excessive shade,also it does not favour very high temperatures above 45 deg cent. During thefruit set and development. Heavy rains and cloudy weather during floweringadversely affect the yield.

Soil: The Cashew is cultivated on a wide variety of soils. It is considereda crop of marginal land and is recommended for slopy and light soils. Thebest soils for better production are deep, friable, well drained and without ahard pan upto 2/3 m in depth. The Cashew is mainly grown on Laterite, redand coastal sands in India.

Varieties: The following are the important varieties of Cashew grown indifferent parts of the country.

i. Vengurla 1ii. Vengurla 2iii. Vengurla 3


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iv. Vengurla 4v. Vengurla 5vi. Vengurla 6vii. Bhubaneshwarviii. Kanakaix. Dhanax. SelectionPropagation: The cashew is grown by the following methods:i. Seed Propagation: It is the oldest and cheapest method of propagation.

It is also used to raise the plants for the purpose of graftingii. Layering this method is more successful in coastal and more humid

areasiii. Soft Wood Grafting: This is followed both in the nursery as well as

in the field of in-situ. For this purpose, veener grafting is doneiv. Top-working: This method is used not for propagation but for

converting inferior free into desirable onePlanting and Season: Normally cashew grafts are planted at the spacing

of 7.0 x 7.0 or 7.5 x 7.5 or 8.0 x 8.0 m on plain land or on desirable contours onslopy lands. After marking, the pits of 60x60x60 cm are dug and filled with acompost,top soil, single super phosphate and karnaj cake. This is to be wellbefore the monsoon starts. Planting should be done during June-July i.e. inthe beginning of monsoon.

Interculturing:i. Removal of weeds is done once twiceii. Intercrops are planted in interspaceiii. Some perenial forest plants and/or some seasonal crops can be taken

as per the local need and situationCare of young orchard:i. Gap filling for the missing plantsii. Removal of outgrowth on stocks in case of grafted plantsiii. Staking with bamboosiv. Cover croppingv. Providing protective irrigation during first few summers. These are

some of the points for young plantationsSpecial Horticultural practices:i. Pruning of dead and dried shoots alongwith crisscross branches

and water shootsii. Pruning of leader shoots in June followed by 2% KNO3 sprayiii. Spraying with 10 ppm NAA twice during flowering for increasing

fruit set and minimizing flower and fruit drop1. Irrigation: The cashew is mostly grown as the rainfed crop and

requires no irrigation in the high rainfall areas. However, if therainfall is low, the cashew responses well to irrigation water at


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the time of fruit set upto full development stage of nuts. Irrigationshould not be given before or at the time of flowering, as it islikely to promote vegetative growth

2. Nutrition: To improve the growth and yield the cashew trees shouldbe manured and fertilized with bio-fertilizers like biomeal and NpK500,200, 200 gm per tree per year. Spraying with ultrazyme and8:12:24:4 NPKmg twice, during fruit development is useful toincrease size and yield of nuts

3. Plant Protection: The crop particularly blossom and fruits should beprotected against Tea Mosquito, Stem and root borer is also animportant pest. Leaf minor, Leaf and blossom webber, Flower thripsare the common pests in neglected orchards. Inflorescence blight,pink disease, and anthrac nose are some diseases found on cashew.Clean cultivation, pruning, better aeration and preventive measuresshould be adopted besides occassional sprays of selected pesticidesand fungicides

4. Harvesting and Yield: The Cashew comes to its full bearing stage atthe age of 10th year and continuous to give yield further for 30-40years. Usually the nuts are collected after they fall off from the tree.They are separated from apples and dried for 2/3 days to reducethe moisture. Regarding yield there is a wide variation anddifferences of opinions. However, the desirable variety at goodmanagement yields 50 kg of raw nuts

5. Post Harvest Handling: The processing of raw nuts involves roasting,shelling, drying, peeling, grading and packing 'A' grade nuts arealways in demand from the outside markets and fetch a good price.A Fenny like drinks are prepared from the apples


217

Vegetable and Fruit Production

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