Course of dry matter and nitrogen accumulation of spring wheat genotypes (Triticum aestivum L.)...

This article was downloaded by: [Nagref ]On: 08 May 2013, At: 00:32Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Journal of Plant NutritionPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/lpla20

COURSE OF DRY MATTER AND NITROGENACCUMULATION OF SPRING WHEATGENOTYPES KNOWN TO VARY INPARAMETERS OF NITROGEN USEEFFICIENCYChristos Noulas a , Ioannis Alexiou a , Juan M. Herrera b & PeterStamp ca National Agricultural Research Foundation, Institute for SoilMapping and Classification 1 , Larissa , Greeceb Institute of Plant Sciences, Swiss Federal Institute of Technology ,Lindau , Switzerlandc Institute of Plant Sciences, Swiss Federal Institute of Technology ,Zürich , SwitzerlandAccepted author version posted online: 05 Mar 2013.Publishedonline: 02 May 2013.

To cite this article: Christos Noulas , Ioannis Alexiou , Juan M. Herrera & Peter Stamp (2013): COURSEOF DRY MATTER AND NITROGEN ACCUMULATION OF SPRING WHEAT GENOTYPES KNOWN TO VARY INPARAMETERS OF NITROGEN USE EFFICIENCY, Journal of Plant Nutrition, 36:8, 1201-1218

To link to this article: http://dx.doi.org/10.1080/01904167.2013.779706

PLEASE SCROLL DOWN FOR ARTICLE

Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions

This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden.

The publisher does not give any warranty express or implied or make any representationthat the contents will be complete or accurate or up to date. The accuracy of anyinstructions, formulae, and drug doses should be independently verified with primarysources. The publisher shall not be liable for any loss, actions, claims, proceedings,demand, or costs or damages whatsoever or howsoever caused arising directly orindirectly in connection with or arising out of the use of this material.

http://www.tandfonline.com/loi/lpla20

http://dx.doi.org/10.1080/01904167.2013.779706

http://www.tandfonline.com/page/terms-and-conditions

Journal of Plant Nutrition, 36:1201–1218, 2013Copyright C© Taylor & Francis Group, LLCISSN: 0190-4167 print / 1532-4087 onlineDOI: 10.1080/01904167.2013.779706

COURSE OF DRY MATTER AND NITROGEN ACCUMULATION

OF SPRING WHEAT GENOTYPES KNOWN TO VARY IN PARAMETERS

OF NITROGEN USE EFFICIENCY

Christos Noulas,1 Ioannis Alexiou,1 Juan M. Herrera,2 and Peter Stamp3

1National Agricultural Research Foundation, Institute for Soil Mapping and Classification1, Larissa, Greece2Institute of Plant Sciences, Swiss Federal Institute of Technology, Lindau, Switzerland3Institute of Plant Sciences, Swiss Federal Institute of Technology, Zurich, Switzerland

� Field experiments were conducted for two years to compare and identify bread spring wheat(Triticum aestivum L.) genotypes which make the most efficient use of nitrogen (N). Such in-formation is required for breeding strategies to reverse the negative relationship between yield andprotein content. Three Swiss spring wheat cultivars (‘Albis’, ‘Toronit’, ‘Pizol’) and an experimentalline (‘L94491’) were grown without (N0; 0 kg N ha−1) and with high fertilizer N [(NH4NO3);(N1; 250 kg N ha−1) supply on a clay loam soil with low organic matter content. Biomass andnitrogen accumulation in biomass as well as the leaf growth and senescence patterns (SPAD) wereinvestigated in an attempt to explain the physiology of growth and N translocation of these geno-types. The pre-anthesis accumulation of biomass and N in the biomass depended on genotype only atN1 in 2000. In this year, conditions were less favorable for the pre-anthesis accumulation of biomassand N, which was, on average, 10 and 20% lower, respectively, of the total than in 1999. The con-tribution of pre-anthesis assimilates to the grain yield (CPAY) was higher in 1999 for all genotypes(36.9%) compared to 2000 (13.5%) except ‘Toronit’. Between anthesis and maturity the climateinfluenced the genetic variability of some N use efficiency components: N translocation efficiency(NTE) and dry matter translocation efficiency (DMTE). NTE was higher in 1999 (68.1%) com-pared to 2000 (50.7%); 1999 was a year in which the post-anthesis period was drier and warmerthan usual. ‘Toronit’ produced the highest biomass by maturity due mainly to greater and longerlasting green leaf area after anthesis. ‘Albis’ performed relatively well under low input conditions,with considerable amounts of N being re-translocated to the seeds at maturity (NHI), whereas ‘Pizol’accumulated in grains N as high as for ‘L94491’. In a humid temperate climate breeding for greaterN uptake and partitioning efficiency may be a promising way to minimize N losses and produce highphytomass and grain yields. Using high protein lines as selection material and combining them withhigh biomass genotypes may lead to high protein contents without decreasing yield.

Received 1 October 2010; accepted 1 June 2011.Address correspondence to Christos Noulas, National Agricultural Research Foundation, In-

stitute for Soil Mapping and Classification 1, Theophrastou Str. 41335, Larissa, Greece. E-mail:[email protected]

1201

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013

1202 C. Noulas et al.

Keywords: spring wheat, dry matter accumulation, nitrogen accumulation, nitrogenuse efficiency parameters

INTRODUCTION

Yield potential and grain protein content of a wheat crop are crucial de-terminants of its profitability and product quality. Nitrogen (N) is the mostimportant element for both determinants and its efficient use is econom-ically and environmentally indispensable, apart from its agronomic value.Nitrogen use efficiency (NUE) of cereals worldwide is relatively low andmethods for increasing it are being investigated (Raun and Johnson, 1999;Fageria and Baligar 2005; Fageria et al., 2008).

A wheat genotype that uses N efficiently can be defined as a genotype thatabsorbs large amounts of N from the soil and from fertilizer, producing highgrain yield per unit absorbed N and leaving only little N in the straw. How-ever, it is difficult to improve simultaneously grain yield and grain proteinpercentage through breeding because of the common negative relationshipbetween these traits (Feil, 1997). This negative relationship between grainprotein concentration (GPC) and grain yield is crucial in breeding for yieldand further attempts must be made to overcome it. Worldwide, wheat yieldsincreased slightly and insignificantly during the last decade, indicating astate of a leveling off and genetic improvements are needed to keep raisingyields and meet future population demands (Slafer et al., 2001).

Higher grain protein yields can be achieved by two major ways: firstly,by increasing the N harvest index (NHI = proportion of seed N to totalshoot N), which is high in Switzerland and central to northern Europe >

0.80, (Banziger et al., 1994b) a very variable trait, which is strongly affectedby the environment and is not a promising selection criterion. Secondly, byenhancing the amount of N in the plant by breeding for a higher N uptake.Dhugga and Waines (1989) concluded that uptake efficiency is slightly moreimportant than utilization efficiency in determining NUE, especially underconditions of high amounts of available N in the soil. The role of available Nin the soil is very important in N uptake (Ortiz-Monasterio et al., 1997), es-pecially with late N application and good soil moisture conditions (Banzigeret al., 1994b).

Several field experiments were conducted to determine genetic variationin the N uptake and utilization in winter wheat (Le Gouis et al., 2000) tomeasure genetic progress in grain yield and NUE (Ortiz-Monasterio et al.,1997), to identify cultivars with high GPC and yield (Monaghan et al., 2001)and to determine the improvement of NUE through plant breeding (VanGinkel et al., 2001). Other studies considered the importance of biomass,N accumulation, and remobilization during grain filling for grain yield andgrain N (Cox et al., 1985a, 1985b, 1986; Papakosta and Gagiannas, 1991) or

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013

Biomass and N Accumulation of Spring Wheat 1203

determined whether an increase in N accumulation during grain filling re-duces carbohydrate availability for grain formation (Banziger et al., 1994a).

The anthesis stage of wheat is particularly important since it representsthe transition from the vegetative to the reproductive phase of growth; thepost-anthesis utilization of assimilates and energy may lead to competitionbetween dry matter and protein production (Bhatia and Rabson, 1976).Mobilization of the pre-anthesis mass of assimilates between anthesis andmaturity and the efficiency of the conversion of mobilized pre-anthesis as-similates into grain may play an important role in grain filling (Gebbinget al., 1999). The pre-anthesis accumulation of N seems to be the mainsource of N during seed growth and the development of wheat (Van San-ford and MacKown, 1987) and can be as high as 90 to 102% of total plant Nat maturity, depending on the experimental conditions (Clarke et al., 1990;Heitholt et al., 1990). However, wheat retains the capacity to take up N afteranthesis (Van Sanford and MacKown, 1987; Oscarson et al., 1995a). Lateapplication of N usually increases the leaf N concentration and may delayleaf senescence, especially under moist conditions (Banziger et al., 1994a).Genotypic variability is evident in the post-anthesis uptake of N (Cox et al.,1985b; Monaghan et al., 2001). Up to 50% of total N was taken up afteranthesis (Spiertz and Ellen, 1978; Van Sanford and MacKown, 1987). Coxet al. (1985b) found that post anthesis N uptake was more strongly relatedto grain yield and total grain N than to GPC. Additionally, leaf growth is akey determinant of plant N demand, because the photosynthesis of leavesrequires a large amount of reduced N compared to the photosynthesis ofother plant tissues (Novoa and Loomis, 1981).

The present study followed the course of biomass formation and N ac-cumulation of four spring wheat genotypes with different yield and grainprotein potential for two growth periods in a temperate climate. We de-termined whether: i) low (zero N; N0) or high N (N1) contributes to thegenotypic variability of biomass and N accumulation, especially at anthesis,ii) genetic variability in dry matter and N translocation during grain fillingcan be explained indirectly by physiological traits. Genetic possibilities forcircumventing the negative yield-protein relationship are discussed.

MATERIALS AND METHODS

The Experiments

The field experiments were conducted for two years (1999 and 2000) inthe Swiss midlands (550 m above sea level), at the experimental station ofthe Institute of Plant Sciences near Zurich (47◦ 26′ N, 8◦ 40′ E).

The Swiss spring wheat cultivars ‘Albis’, ‘Toronit’ and ‘Pizol’ and theexperimental line 94491 (‘L94491’) (Banziger et al., 1992) were bred atthe Swiss Federal Research Station in Reckenholz and were used in bothexperiments. ‘Albis’ and ‘L94491’ are medium early genotypes and ‘Toronit’

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


and ‘Pizol’ medium late with respect to ear emergence. ‘Albis’ has a mediumyield potential and protein content. ‘Toronit’ is characterized by higher yieldpotential and somewhat lower protein content than ‘Albis’. ‘L94491’ wasincluded in the experiment because of its high grain protein concentration,despite its lower yield potential. The yield potential of ‘Pizol’ is similar tothat of ‘Albis’ and its protein content is similar to that of ‘L94491’. ‘Pizol’ isthe genotype that was released more recently than the other ones.

The studied soils have been classified as Inceptisols (Soil Survey Staff,2003) with clay loam (CL) texture. At soil depths of 0 to 30, 30 to 60 and 60to 90 cm, the mineral soil nitrogen content at the beginning of the season[nitrate (NO3

–) plus ammonium (NH4+), Kjeldahl] was 24.5, 21.5 and 20.5

Kg ha−1 respectively in 1999 and 21.0, 11.0 and 6.8 kg ha−1, respectivelyin 2000. The contents of phosphorous (Olsen) and potassium [assimilablepotassium oxide (K2O), NH4 acetate] were sufficient to a depth of 30 cm[0.40 g phosphorus (P) kg −1 and 26.7–36.5 ppm]. The soil was poor in soil or-ganic matter (3%, Walkley-Black), and neutral to slightly alkaline [pH(H2O) =6.7 to 7.7].

The extended BBCH scale (Lancashire et al., 1991) was used to describethe phenological development of 50% of the plants in each plot. Hereafter,the stages will be mentioned only with the responding stage number.

Plot size was 18 m2 and seeding depth was 20–30 mm. Half of the plotswere not fertilized with N (N0) and the rest were fertilized with 250 kg Nha−1 (N1) as ammonium nitrate (NH4NO3). The N fertilizer was dividedinto four doses: 90 kg N ha−1 at sowing, 40 kg N ha−1 at stem elongation(BBCH stage 30), 60 kg N ha−1 at heading (BBCH stage 50) and 60 kg Nha−1 at anthesis (BBCH stage 60).

Agrochemical protection was performed when necessary during thegrowth periods. A growth regulator Moddus R© (Syngenta Agro AG, Basel,Switzerland) (0.5 l ha −1) was sprayed in both experimental years at the1-node stage (BBCH stage 30–32), to prevent subsequent lodging. The pre-ceding crops were potatoes (Solanum tuberosum L.) in 1999 and ryegrass(Lolium perenne L.) in 2000.

Data Sampling

Sowing of the trials was performed on 17 March and on 22 March 1999and 2000, respectively. Shoot samplings were conducted at stem elongation(BBCH stages 30–31; on 10 May 1999 and on 11 May 2000), flag leaf emerged(BBCH stages 37–39; on 26 May 1999 and on 26 May 2000), flowering (BBCHstage 65; on 17 June 1999 and on 13 June 2000), medium to late milk (BBCHstages 75–80; on 8 July 1999 and on 3 July 2000) and at physiological maturity(BBCH stage 91 and 92; on 11 August 1999 and on 8 August 2000).

Plants at all harvests were cut at ground level using hand sickles froman area of 0.18 m2 of the two central rows and at maturity from an area of0.54 m2 from the three central rows in each plot.

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


Right after determination of fresh weight the shoots were processed atthe laboratory. A random shoot sub-sample was collected and the green leafblades (without leaf sheaths) were separated to determine the green leafarea. The area of the blades was measured with a ′Mark 2′ leaf area meterwith a belt conveyor (Delta-T devices, Burwell, Cambridge, England). Thetransformation to LAI (leaf area index) was made by dividing the area of thesoil occupied by each sample at each developmental stage.

After drying in an oven at 65◦C for at least 48 h, the shoot materialof the first three sampling dates (BBCH stages: 30–31, 37–39 and 65) wasthoroughly mixed, ground and prepared for analyses of total N. Shoots ofthe two last samplings (BBCH stage 75–80 and at maturity) were threshedand separated into grains, chaff (rachis plus glumes and awns) and straw; thedry weight was determined (chaff and straw were mixed thoroughly beforeweighing and will be referred to as straw hereafter).

The straw was ground twice using mills with 3-mm (Wolf Muhle, Wien,Austria) and 1-mm sieves (Cyclotec Tecator 1093 Mill, Tecator AB, Hoganas,Sweden). Grains were ground once with an A 10 mill (Janke & KunkelLabortechnik, Staufen I Br., Germany). Analyses of plant tissue materialfor total N were performed with a LECO CHN-1000 auto analyzer (LECOCorporation, St. Joseph, MI, USA).

The leaf greenness was determined on the blades of fully expanded flagleaves at regular intervals using a SPAD-502 m (Minolta, Plainfield, IL, USA).Measurements were taken during the afternoon and recorded as the meanof 10 randomly selected main stems per plot. The SPAD meter readingswere used to assess the profiles of the decline in the greenness of leaves(Dwyer et al., 1991; Chapman and Barreto 1997; Sadras et al., 2000). SPADmeter readings were taken at six principal stages. Late booting (BBCH stages47–49), medium to late heading (BBCH stages 57–59), flowering (BBCHstages 64–69), milk to dough (BBCH stages 70–80), ripening (BBCH stage85) and senescence (on the fertilizer plots, at BBCH stage 89) for the fieldexperiments in 1999. For the field experiment in 2000 the first series ofmeasurements were performed slightly earlier (BBCH stage 32+), whereasall the other samplings were the same as those in 1999. Meteorological datawere obtained from a weather station 500 m away.

Methods of Calculations

Nitrogen utilization efficiency (grain yield produced per unit total shootN) and N harvest index (NHI) were calculated with the following formulasaccording to Huggins and Pan (1993):

(i) Nitrogen utilization efficiency = Gw/Nt,

where Gw = grain yield in (kg ha−1);

Nt = total above ground plant N at physiological maturity

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


(ii) NHI = Grain N yield / biomass N yield

N translocation efficiency from vegetative plant parts to grain (NTE;%),dry matter translocation efficiency (DMTE;%), contribution of pre-anthesisassimilates to grain yield (CPAY;%) and dry matter translocation (DMT; kgha−1) were calculated according to the formulas of Papakosta and Gagiannas(1991).

(iii) NTE = Nshoot anthe s is − Nstr aw matur i t y

Nshoot anthe s is× 100,

where N in shoot or straw in (kg ha−1)

(iv) DMT = Dry matter at anthesis - straw dry matter at maturity

(v) DMTE = Dry matter translocationDry matter at anthesis × 100

(vi) CPAY = Dry matter translocationGrain yield × 100,

where dry matter and grain yield in (kg ha−1).

Experimental Design and Statistical Analyses

The experimental design was a split plot with four replications in bothyears. Rates of N fertilization in the main plots and spring wheat genotypesin the subplots were selected to minimize border effects between plots thatwere fertilized at different rates. The main plot size (fertilizer level) was72 m2, and the subplot size (cultivar plot) 18 m2. The results of each yearand each developmental stage were analyzed separately by means of analysisof variance (ANOVA) using the MIXED procedure of the Statistical AnalysisSystem (SAS Institute Inc., Cary, NC, USA; Littell et al., 1996). Genotypesand N fertilizer rates were considered to be fixed effects; block and the inter-action block × N fertilizer rate were considered to be random effects. Thepair-wise t rest was used for mean separation when F tests were significant.

RESULTS

Weather Conditions during Development

The mean temperature was quite similar (∼14.5◦C) in each growth sea-son of spring wheat (March to August), in 1999 and in 2000 (Figure 1).However, it was warmer from April to June in 2000 than in 1999 andthis contributed to the faster development of wheat as early as stage 31.The growing season in 1999 was wetter (by 100 mm) than in 2000, with aconsiderably different distribution of rainfall in May, June and July. Precipi-tation in May 1999 was markedly higher than in 2000 and higher than thatin Eschikon during the past sixteen years, amounting to almost one third of

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


FIGURE 1 Mean monthly precipitation and mean air temperature during the two growth seasons.

the precipitation that fell during the entire cropping season. July was wetterthan normal in 2000 (grain filling period), whereas 1999 was closer to themean. May and June (pre-anthesis and anthesis periods) were drier in 2000than in 1999 and than in the previous sixteen years.

Shoot Biomass and N Accumulation

The temporal patterns of dry matter accumulation and N in the biomassof the two growing seasons are shown in Figure 2 and in Figure 3. In 1999accumulation of shoot biomass of the genotypes tended to follow a similartemporal pattern as N biomass accumulation. These similarities were lesspronounced in 2000. Few and weak indications of significant genotypic vari-ation were found for both traits at both N levels in the both growing seasons.

In 2000 at N1 plants (Figure 2, B: 2000) at stem elongation (∼50d.a.s.) showed few significant genotypic differences in biomass accumula-tion, whereas the genotypic differences in the N biomass accumulation ofN1 plants (Figure 3, B: 2000) were already pronounced at stage 30 (50 d.a.s)and at mid-anthesis (83 d.a.s). ‘Albis’, relative to ‘Toronit’, with a few excep-tions at initial growth stages, showed mostly a lower total biomass at bothN levels and years until maturity. ‘Pizol’ or ‘L94491’, accumulated morebiomass by stage 75 to 80 (∼113 d.a.s in 1999) or earlier (∼80 d.a.s in 2000)

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


A: 1999

X Data

Rel

ativ

e to

tal s

hoot

dry

mat

ter

0.6

0.8

1.0

1.2

1.4

1.6

B: 1999

Days after sowing54 70 92 113 147

0.6

0.8

1.0

1.2

1.4

A: 2000

0.6

0.8

1.0

1.2

1.4

1.6

B: 2000

50 65 83 102 1380.6

0.8

1.0

1.2

1.4

1) 0.07 0.15 0.51 0.85 0.89

1) 0.10 0.26 0.84 1.21 1.45

1) 0.08 0.26 0.57 0.93 0.93

1) 0.13 0.41 0.90 1.51 1.68

stage 65

stage 65stage 65

stage 65

2) *

*

***AlbisL94491PizolToronit

FIGURE 2 Total shoot dry matter accumulation without (A: 0 kg N ha−1) and with (B: 250 kg N ha−1) Nsupply in two growing seasons. Values are expressed relative to those observed for ‘Toronit’. 1) Absolutevalues (kg ha−1) of the genotype ‘Toronit’. 2) ∗, significant differences in shoot dry matter accumulationat 0.05 probability level.

in both growing seasons especially under N1. However, by maturity ‘Toronit’again had the largest amount of shoot biomass at both N levels.

Accumulation of N in the biomass was significantly different betweenthe genotypes only at N1 in 2000 (Figure 3, B: 2000). While at N0 ‘Albis’showed higher values than ‘Toronit’ during intermediate growth stages,‘Albis’ was clearly inferior to ‘Toronit’ at N1 and accumulated significantlylower amounts of N in the biomass by maturity. Initially ‘L94491’ seemed toaccumulate more N in the biomass than ‘Toronit’. This advantage was lostbetween ∼80 to 100 d.a.s in 2000 at both N levels.

Kinetics of Dry Matter and N during Grain Filling

All genotypes showed around 17% higher NTE from vegetative plantparts to grain in 1999 compared to 2000; the genotypes varied in NTE inboth years (Table 1). ‘Albis’ had consistently high values, whereas ‘L94491’

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


A: 1999

0.6

0.8

1.0

1.2

1.4

1.6

B: 1999

Days after sowing54 70 92 113 147

Rel

ativ

e N

bio

mas

s yi

eld

0.6

0.8

1.0

1.2

1.4

A: 2000

0.6

0.8

1.0

1.2

1.4

1.6

B: 2000

50 65 83 102 1380.6

0.8

1.0

1.2

1.4

1) 1.95 2.93 4.76 7.62 9.50

1) 5.10 8.96 18.52 21.71 24.7

1) 2.21 3.75 5.87 7.20 10.20

1) 4.12 12.68 23.59 28.39 31.40

2) *

stage 65

stage 65

stage 65

stage 65

** ***

*


FIGURE 3 Accumulation of N in biomass without (A: 0 kg N ha−1) and with N supply (B: 250 kg Nha−1) in two growing seasons. Values are expressed relative to those observed for ‘Toronit’. 1) Absolutevalues (g m−2) of the genotype ‘Toronit’. 2) ∗, ∗∗, ∗∗∗ significant differences in shoot N accumulation at0.05, 0.01 and 0.001 probability levels respectively.

had high values in 1999 and very low values in 2000. DMTE was, on average,higher in 1999. ‘Toronit’ was the only genotype that did not show a decreasein the dry weight of the vegetative parts after anthesis, as indicated by thesignificantly lowest negative values.

The proportion of yield provided by pre-anthesis assimilates (CPAY) was,on average, lower in 2000 than in 1999. In 1999 ‘Toronit’ had the significantlylowest, missing CPAY whereas, values were high for the other genotypes andwere related to DMTE values, respectively. In 2000 no significant differenceswere observed among the genotypes.

Gw/Nt and NHI

Genotypes differed significantly in Gw/Nt at both N levels and in bothyears. NHI was significantly different at both N levels in 1999 and at N1 in2000 (Table 2).

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


TABLE 1 Results of the ANOVA for genotype (G) and nitrogen fertilization (N) and effects of theirinteraction (G × N) on NTE (N translocation efficiency from vegetative plant parts to grain, %), DMTE(dry matter translocation efficiency, %) and CPAY (contribution of pre-anthesis assimilate to yield, %).Data represent means of two N levels

NTE (%) DMTE (%) CPAY (%)

Pr > F

1999G 0.024 0.002 0.045N 0.004 0.818 0.809G × N 0.878 0.855 0.993

2000G 0.051 0.950 0.985N 0.006 0.002 0.063G × N 0.923 0.838 0.702

Means1999

‘Albis’ 75.0a 21.2a 38.7ab‘L94491’ 69.6ab 26.3a 62.2a‘Toronit’ 62.1b −1.9b −0.5b‘Pizol’ 65.6b 15.8a 47.2aMean 68.1 15.4 36.9

2000‘Albis’ 53.3a 10.6 13.0‘94491’ 41.0b 7.9 14.7‘Toronit’ 54.5a 9.4 12.4‘Pizol’ 53.9a 8.6 14.0Mean 50.7 9.1 13.5

Means followed by different letters are different at P < 0.05 according to pair-wise t-test comparisons.

TABLE 2 Genotype (G), nitrogen fertilization (N) and effects of their interaction (G × N) on Nutilization efficiency (Gw/Nt) and N harvest index (NHI) for spring wheat (N0; 0 kg N ha−1, N1; 250 kgN ha−1)

Gw/Nt (kg kg −1) NHI (%)

G N G × N G N G × N

1999 Pr > F < 0.001 < 0.001 0.146 0.001 < 0.001 0.0342000 Pr > F < 0.001 < 0.001 0.014 0.005 < 0.001 0.032

N0 N1 Mean N0 N1 Mean1999 ‘Albis’ 42.3a 28.1a 35.2a 85.6a 73.7a 79.6a

‘L94491’ 36.0b 25.8b 30.9b 81.3b 74.1a 77.7ab‘Toronit’ 38.5ab 24.5b 31.5b 83.2ab 68.0b 75.6b‘Pizol’ 34.5b 24.1b 29.3b 80.6b 66.8b 73.7bMean (cvs) 37.8 25.6 31.7 82.7 70.7 76.7

2000 ‘Albis’ 40.6 27.3 33.9 78.7 67.2 72.9‘L94491’ 33.1 22.8 28.0 76.1 69.8 72.9‘Toronit’ 43.5 26.6 35.1 76.7 63.1 69.9‘Pizol’ 37.5 23.6 30.5 74.4 64.2 69.3Mean (cvs) 38.7 25.1 31.9 76.5 66.1 71.3

Means followed by different letters are different at P < 0.05 according to pair-wise t-test comparisons.

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


The N effect was significant in both years and for both components.Interactions G × N were significant for both components in 2000 but onlyfor NHI in 1999.

‘Toronit’ showed significantly higher Gw/Nt at N0 and N1 in 2000 com-pared to ‘L94491’ or ‘Pizol’. Compared to ‘Toronit’, ‘Albis’ showed a higherGw/Nt and NHI. With the exception of the significantly higher NHI at N1in both years, ‘L94491’ and ‘Pizol’ had the lowest or medium to low valuesfor Gw/Nt.

Temporal Patterns LAI and SPAD

The temporal patterns of LAI and SPAD are presented in Figures 4 and5, respectively. Significant genotypic variability in LAI at N0 was found atstages 75 to 80 in both years (Figure 4, A: 1999 and A: 2000; 113 d.a.s in1999 and 102 d.a.s in 2000), with the highest values for ‘Toronit’, despiteinitially comparable ones. At N1 the genotypes exhibited similar patternsof LAI values, but the relative differences were smaller, despite the meanhigher absolute values at N1.

A: 1999

Rel

ativ

e le

af a

rea

ind

ex (

LA

I)

0.0

0.5

1.0

1.5

2.0

B: 1999

Days after sowing54 70 92 113

0.0

0.5

1.0

1.5

A: 2000

50 65 83 102

B: 2000

1) 1.06 1.06 1.61 1.37

1) 1.77 2.79 3.43 2.70

1) 1.11 1.40 1.18 1.09

1) 1.65 3.41 3.46 2.88

2)*

stage 65

*

stage 65stage 65

stage 65

*

***

*

*

*


FIGURE 4 Relative LAI values without (A: 0 kg N ha−1) and with N supply (B: 250 kg N ha−1) in twogrowing seasons. Values are expressed relative to those observed for ‘Toronit’. 1) Absolute LAI values ofthe genotype ‘Toronit’. 2) ∗, ∗∗∗ significant differences among genotypes at 0.05 and 0.001 probabilitylevel respectively.

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


A: 1999R

elat

ive

SP

AD

val

ues

0.6

0.8

1.0

1.2

1.4

B: 1999

Days after sowing

77 84 91 99 106 116 121 126

0.6

0.8

1.0

1.2

A: 2000

0.6

0.8

1.0

1.2

1.4

B: 2000

54 75 83 89 96 102 110 116

0.6

0.8

1.0

1.2

1) 30.9 28.5 33.8 30.4 30.4 22.4 28.0

1) 45.3 40.6 46.9 44.5 43.9 37.0 30.7 25.0

1) 30.7 40.0 39.8 38.1 35.5 33.4 21.7 18.5

1) 41.5 48.3 50.3 48.9 48.4 48.4 42.5 29.5

2) ***

**** *

*

****

*** ** ****

*

* * * * * * * * **

*****

stage 65

stage 65

stage 64

stage 64

yAlbisL94491PizolToronit

FIGURE 5 Relative SPAD meter readings without (A: 0 kg N ha−1) and with N supply (B: 250 kg N ha−1)in two growing seasons. Values are expressed relative to those observed for ‘Toronit’. 1) Absolute SPADmeter readings of the genotype ‘Toronit’. 2) ∗, ∗∗, ∗∗∗ significant differences among genotypes at 0.05,0.01 and 0.001 probability level respectively.

Significant genotypic differences in SPAD meter readings were observedat most of the stages in both growing seasons and at both N levels (Fig-ure 5). ‘L94491’, ‘Albis’ and ‘Pizol’ showed higher SPAD meter readingsat N0 than ‘Toronit’ for most of the growing season. However, ‘Toronit’had higher values towards the end of the season. After an initial ad-vantage over ‘Toronit’, the greenness of ‘L94491’ at N1 decreased afterabout 106 d.a.s in 1999 (as at N0). However, in 2000 the values were notlower than of those of ‘Toronit’, while ‘Albis’ and ‘Pizol’ generally exhib-ited similar patterns as ‘Toronit’; ‘Albis’ usually had higher values than‘Toronit’.

DISCUSSION

Shoot Biomass and N Accumulation by Anthesis and Maturity

Except the genotype ‘Toronit’ in 1999 and ‘L94491’ in 2000, all geno-types had accumulated by anthesis more than 50% (in 1999 >70%) of their

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


total shoot biomass or N in the biomass at both N levels (data based on cal-culation from absolute values). These values were close to those reported byVan Sanford and MacKown (1987), who found that 8 to 35% of the total Nwas taken up after anthesis. Clarke et al. (1990) found that the total uptakeof N was proportional to the available water, was strongly associated with drymatter accumulation and from 67 to 102% of total plant N at harvest hadbeen accumulated by anthesis. However, Cox et al. (1985b) concluded thatdespite a pre-anthesis accumulation of N of more than 80% of the total N as-similated by maturity, only a small part of the variation in total N assimilationcould be explained by pre-anthesis values in 96 wheat lines.

At anthesis, significant differences in dry matter and N in the biomasswere found only in 2000 at high N availability. The moderately late geno-types (‘Toronit’ and ‘Pizol’) accumulated more biomass and more N inthe biomass than the moderately early genotypes (‘Albis’ and ‘L94491’)similar to the findings of Kumakov et al. (2001) and to Cox et al.(1985a), who found significant differences among F5 lines under high Nsupply.

As expected and in agreement with previous findings (Noulas et al.,2004), ‘Toronit’ had accumulated more biomass at both levels of N supplyin both years by maturity. Nitrogen accumulation in the biomass was higherfor ‘Toronit’ under both N levels in 1999, mainly due to its greater amount ofbiomass. Under high N supply in 2000, ‘L94491’ accumulated even more Nin the biomass (significantly higher than ‘Albis’), probably due to its higherpost anthesis N uptake (Noulas et al., 2010).

Kinetics of Dry Matter and N-Related Parameters

The relatively warmer and drier weather conditions in July 1999 com-pared to 2000 may have favored greater NTE from the vegetative plant partsafter anthesis to the grain for all genotypes (Table 1). Campbell et al. (1983)and McNeal et al. (1968) agree that such conditions favor greater transportof N to the grains. These conditions may also reduce final grain yield as aresult of high respiration rates, a faster senescence of the photosyntheticorgans and reduced starch accumulation (Nicolas et al., 1984). In absoluteterms, the comparatively lower from anthesis to maturity SPAD meter read-ings (senescence pattern of the canopy) and the lower LAI values at stages75 to 80 in 1999 than in 2000, especially at high N supply support this obser-vation. Accordingly, higher on average GPC in 1999 at both N environmentswere favored under the same conditions (Noulas et al., 2004). In many in-stances, GPC appears to increase with increasing temperature and reducedrainfall, as reported by Hopkins (1968) for Canadian hard red spring wheator by Schipper (1991).

In 1999, NTE was higher for ‘Albis’; values in 2000 were among the high-est, probably as a result of higher SPAD meter readings recorded for this

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


genotype later in both seasons (Figure 4). Thus, this genotype continued totranslocate leaf N during grain filling. Simpson et al. (1983) postulated thatleaves contribute more actively than stems to N translocation to the grainafter anthesis; Vidal et al. (1999) found that the relationship between SPADmeter readings and N exportation was better than with tissue N concentra-tion. Moreover, this genotype showed a loss of green leaf area (Figure 3),which was often significant when compared to other genotypes and probablycontributed to a lower photosynthetic activity and greater remobilization ofvegetative N during grain filling (Frederick, 1997).

Negative values for DMTE (no decrease in the weight of the vegetativeplant parts after anthesis) and the lack of pre-anthesis assimilates to yield(CPAY) that were recorded for ‘Toronit’ in 1999, suggest that the yield ofthis high-yielding, moderately late genotype may have depended mainly oncurrent photosynthesis during grain development. This genotype showed asignificantly higher green leaf area during this period (Figure 3). In contrastthe lower-yielding, high-protein ‘L94491’ exhibited a significantly higherCPAY in 1999. Similar trends were recorded by Cox et al. (1985a) for thespring wheat genotypes ‘Anza’ (high-yielding) and ‘Cajeme 71’ (higher-protein). Moreover, the results of our study in 1999 were supported by higherSPAD meter readings for ‘Toronit’ relative to ‘L94491’ from ∼25 days afterflowering until maturity. The CPAY of the other genotypes ranged from 12.4(2000; ‘Toronit’) to 47.2% (1999; ‘Pizol’) in both years. In other studies, thevalues ranged widely: 6 to 73% (Papakosta and Gagiannas, 1991), 7 to 27%(Austin et al., 1977; Bidinger et al., 1977). As in the study of Papakosta andGagiannas (1991), genotypes with a greater biomass at anthesis (i.e., ‘Albis’,‘L94491’ at N0) translocated a greater portion of dry matter between anthesisand maturity. Genetic variability in DMTE was found by other studies (Austinet al., 1977; Davidson and Birch, 1978).

Losses of N from wheat ranged from 16 to 70 kg ha−1 (Wetselaar andFarquhar, 1980) and are inevitable throughout the whole cropping period(i.e., translocation to the root and soil, loss of plant material, gaseous lossesfrom plant tops) (Kanampiu et al., 1997). The study of Rroco and Mengel(2000) showed that the rates of translocation of labeled N into the soilwere low from tillering to ear emergence and increased progressively toattain maximum rates from ear emergence to grain filling; volatile losseswere found to be highest from ear emergence to the beginning of grainfilling. Contrary to Mediterranean conditions, which enhance N loss duringgrain filling (Papakosta and Gagiannas, 1991) under a temperate climate,as in this study, further N gains after anthesis are expected for spring sownwheat, especially with a late application of N near anthesis. The N in thebiomass at anthesis was lower than at maturity at both N levels, and all thegenotypes tended to continue accumulating N in the biomass after anthesisin both growing seasons, as discussed above. Similar results were reportedby Banziger et al. (1994a).

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


A change in the source to sink relationships and steady leaf activity mightbe another explanation for the continued accumulation of N by all genotypesafter anthesis, and especially for ‘Toronit’ in 1999 and for all the genotypesunder high N availability in 2000. The source to sink relationship of the vege-tative organs changes at anthesis, with the ear becoming the most importantsink and the vegetative organs the N source. In 1999 the LAI of ‘Toronit’was significantly higher even earlier from 92 d.a.s (Figure 3); in 2000 thesame was true from 102 d.a.s, indicating a continuing photosynthetic activityof this genotype after anthesis and continuing availability of N for the grain,even under relatively contrasting post anthesis weather conditions.

‘Albis’ was the most efficient genotype in producing grain per unit oftotal plant N at high N supply in both years. However, this genotype wasthe least efficient genotype in producing grain yield per unit of N supply,mainly because of its markedly lower uptake efficiency (Noulas et al., 2010).‘Pizol’ had a limited capacity to translate total plant N into grain yield thusthis genotype may be less efficient in N use. However, especially underconditions of higher N supply, Dhugga and Waines (1989) concluded thatuptake efficiency is slightly more important than utilization efficiency indetermining NUE.

Without N application, ‘Albis’ had stored the highest proportion of totalplant N in the seeds at maturity (NHI), whereas under high N supply thiswas the case for ‘L94491’ in both years.

Conclusions and Implications for Breeding

Of the tested genotypes, ‘Toronit’ showed continued photosyntheticactivity after flowering, thus supporting findings for its good ability to takeup N at flowering and by the end of the season (Noulas et al., 2010). VanGinkel et al. (2001) showed that uptake efficiency is more closely relatedwith yield and biomass improvement at all N levels. On the other handFeil (1997) suggested that breeding for higher above-ground biomass mayindirectly improve the uptake of N, because cultivars with high above-groundphytomass are likely to show vigorous root growth.

There are indications, that under low N conditions, ‘Albis’ translocatedlarge amounts of N from the vegetative plant parts to grain (NTE) afteranthesis and that a large amount of total plant N is stored in the seeds atmaturity (NHI); but the grain yield potential of this genotype is moderate(Noulas et al., 2004) and its ability to take up N is limited (Noulas et al., 2010)both of which may limit the use of this genotype in breeding programs.

‘L94491’ is a high protein genotype compared to ‘Albis’, ‘Pizol’ or‘Toronit’ even though this genotype was characterized by low biomass,early onset of senescence of the canopy and a short period of grain filling(Banziger et al., 1992, 1994b). Talbert et al. (2001) suggested that a longerperiod of grain filling is associated with a larger amount of grain protein in a

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


dry environment that is not irrigated and a smaller amount of grain proteinin a cool, wet environment. In most cases, the duration of grain filling wasnot significantly related to grain yield. Selection for early heading in earlygenerations followed by selection for grain yield and duration of grain fillingin later generations in multi-site trials may circumvent the negative relation-ship between grain yield and grain protein. Selecting for late maturity, onthe other hand, may contribute to an improvement in protein and grainyields, but the inverse yield-protein relationship cannot be overcome by thisbreeding strategy (Banziger et al., 1992, 1994b; Feil, 1997). In soils whereN is limited late maturity may increase grain yield to a greater extent thangrain protein yield. In such cases late maturity will be associated with a lowconcentration of grain protein and vice versa. If sufficient N is available andthe gains in grain yield and grain protein yield are similar, then late maturitywill not cause a decline in GPC. Declining soil moisture, low temperaturesor seeding requirements of subsequent crops may be also limit breeding forlate maturing cultivars (Feil, 1997). ‘L94491’ showed an extraordinary abilityto accumulate and translocate N in the grain, especially under high N, evenunder contrasting weather conditions during crucial stages of development.‘Pizol’ showed a low ability to translocate N in the seeds at maturity (NHI)and to transform total plant N into grain yield (Gw/Nt).

The results of this study demonstrate that genotypes with high biomassand high grain yield potential (i.e., ‘Toronit’) do not simultaneously displayhigh NHI or GPC, independent of the level of N supply. However, high-biomass genotypes seem to be efficient in N uptake (Austin et al., 1977;Desai and Bhatia, 1978). Above-ground biomass maybe positively correlatedwith below-ground biomass (MacKey, 1988). Thus an extensive root systemmay explore soil N more intensively. The positive correlation between aboveand below-ground biomass (Feil, 1992) may indicate that there is still somescope for genetically improving GPC without sacrificing grain yield by usinghigh biomass germplasm.

ACKNOWLEDGMENTS

We thank Dr. Markus Liedgens, Dr. Alberto Soldati and Dr. Boy Feil forthe useful discussions during the experiments and their accurate commentson the preparations of the present manuscript.

REFERENCES

Austin, R. B., J. A. Edrich, M. A. Ford, and R. D. Blackwell. 1977. The fate of dry matter, carbohydratesand 14C lost from the leaves and stems of wheat during grain filling. Annals of Botany 41: 1309–1321.

Austin, R. B., M. A. Ford, J. A. Edrich, and R. D. Blackwell. 1977 The nitrogen economy of winter wheat.Journal of Agricultural Science 88: 159–167.

Banziger, M., B. Feil, J. E. Schmid, and P. Stamp. 1992. Genotypic variation in grain N content of wheatas affected by mineral N supply in the soil. European Journal of Agronomy 1: 155–162.

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


Banziger, M., B. Feil, and P. Stamp. 1994a. Competition between nitrogen accumulation and grain growthfor carbohydrates during grain filling of wheat. Crop Science 34: 440–446.

Banziger, M., B. Feil, J. E. Schmid, and P. Stamp. 1994b. Utilization of late-applied nitrogen by springwheat genotypes. European Journal of Agronomy 3: 63–69.

Bhatia, C. R., and R. Rabson. 1976. Bio-energetic considerations in cereal breeding for protein improve-ment. Science 194: 1418–1421.

Bidinger, F. R., R. B. Musgrave, and R. A. Fischer. 1977. Contribution of stored pre-anthesis assimilate tograin yield in wheat and barley. Nature 270: 431–433.

Campbell, C. A., H. R. Davidson, and T. N. McCraig. 1983: Disposition of nitrogen and soluble sugars inManitou spring wheat as influenced by N fertilizer, temperature and duration and stage of moisturestress. Canadian Journal of Plant Science 63: 73–90.

Chapman, S. C., and H. J. Barreto. 1997. Using chlorophyll meter to estimate specific leaf nitrogen oftropical maize during vegetative growth. Agronomy Journal 89: 557–562.

Clarke, J. M., C. A. Campbell, H. W. Cutforth, R. M. De Pauw, and G. E. Winkleman. 1990. Nitrogen andphosphorus uptake, translocation, and utilization efficiency of wheat in relation to environmentaland cultivar yield and protein levels. Canadian Journal of Plant Science 70: 965–977.

Cox, C. M., C. O. Qualset, and D. W. Rains. 1985a. Genetic variation for nitrogen assimilationand translocation in wheat. I. Dry matter and nitrogen accumulation. Crop Science 25: 430–435.

Cox, C. M., C. O. Qualset, and D. W. Rains. 1985b. Genetic variation for nitrogen assimilation andtranslocation in wheat. II. Nitrogen assimilation in relation to grain yield and protein. Crop Science25: 435–440.

Cox, C. M., C. O. Qualset, and D. W. Rains. 1986. Genetic variation for nitrogen assimilation andtranslocation in wheat. III. Nitrogen translocation in relation to grain yield and protein. Crop Science26: 737–740.

Davidson, J. L., and J. M. Birch. 1978. Responses of standard Australian and Mexican wheat to temperatureand water stress. Australian Journal of Agricultural Research 29: 1091–1106.

Desai, R. M, and C. R. Bhatia. 1978. Nitrogen uptake and nitrogen harvest index in durum wheat cultivarsvarying in their grain protein concentration. Euphytica 27: 561–566.

Dhugga, K. S., and J. G. Waines. 1989. Analysis of nitrogen accumulation and use in bread and durumwheat. Crop Science 29: 1232–1239.

Dwyer, L. M., M. Tollenaar, and L. Houwing. 1991. A nondestructive method to monitor leaf greennessin corn. Canadian Journal of Plant Science 71: 505–509.

Fageria, N. K., and V. C. Baligar. 2005. Enhancing nitrogen use efficiency in crop plants. Advances inAgronomy 88: 97–185.

Fageria, N. K., V. C. Baligar, and Y. C. Li. 2008. The role of nutrient efficient plants in improving cropyields in the twenty first Century. Journal of Plant Nutrition 31: 1121–1157.

Feil, B. 1992. Breeding progress in small grain cereals-A comparison of old and modern cultivars. PlantBreeding 108: 1–11.

Feil, B. 1997. The inverse yield-protein relationship in cereals: Possibilities and limitations for geneticallyimproving the grain protein yield. Trends in Agronomy 1: 103–119.

Frederick, J. R. 1997. Winter wheat leaf photosynthesis, stomatal conductance, and leaf N concentrationduring reproductive development. Crop Science 37: 1819–1826.

Gebbing, T., H. Schnyder, and W. Kuhbauch. 1999. The utilization of pre-anthesis reserves in grainfilling of wheat. Assessment by steady-state 13CO2/12C2 labelling. Plant, Cell and Environment 22: 851–858.

Heitholt, J. J., L. I. Croy, N. O. Maness, and H. T. Nguyen, 1990. Nitrogen partitioning in genotypes ofwinter wheat differing in grain N concentration. Field Crops Research 23: 133–144.

Hopkins, J. W. 1968. Protein content of western Canadian hard red spring wheat in relation to someenvironmental factors. Agricultural Meteorology 5: 411–431.

Huggins, D. R., and W. L. Pan. 1993. Nitrogen efficiency component analysis: An evaluation of croppingsystem differences in productivity. Agronomy Journal 85: 898–905.

Kanampiu, F. K., W. R. Raun, and G. V. Johnson. 1997. Effect of nitrogen rate on plant nitrogen loss inwinter wheat varieties. Journal of Plant Nutrition 20: 389–404.

Kumakov, V. A., O. A. Evdokimova, and M. A. Buyanova. 2001. Dry matter partitioning between organsin wheat cultivars differing in productivity and drought resistance. Russian Journal of Plant Physiology48: 421–426.

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013


Lancashire, P. D., H. Bleiholder, P. Langeluddecke, R. Stauss, T. Van den Boom, E. Weber, and A.Witzenberger. 1991. A uniform decimal code for growth stages of crops and weeds. Annals of AppliedBiology 119: 561–601.

Le Gouis, J., D. Beghin, E. Heumez, and P. Pluchard. 2000. Genetic differences for nitrogen uptake andnitrogen utilization efficiencies in winter wheat. European Journal of Agronomy 12: 163–173.

Littell, R. C., G. A. Milliken, W. W. Stroup, and R. D. Wolfinger. 1996. SAS system for mixed models. Cary,NC: SAS Institute.

MacKey, J. 1988. Shoot:root interrelations in oats. In: Proceedings of the 3rd International Oat Conference,eds. B. Mattsson and R. Lyhagan, pp. 340–344. Lund, Sweden: Svalof.

McNeal, F. H., G. O Boatwright, M. A. Berg, and C. A. Watson. 1968. Nitrogen in plant parts of sevenspring wheat varieties at successive stages of development. Crop Science 68: 535–537.

Monaghan, J. M., J. W. Snape, A. J. S. Chojecki, and P. S. Kettlewell. 2001. The use of grain proteindeviation for identifying wheat cultivars with high grain protein concentration and yield. Euphytica122: 309–317.

Nicolas, M., R. M. Gleadow, and M. J. Dalling. 1984. Effects of drought and high temperature on graingrowth in wheat. Australian Journal of Plant Physiology 11: 553–566.

Noulas C., M. Liedgens, P. Stamp, I. Alexiou, and J. M. Herrera. 2010. Subsoil root growth of field grownspring wheat genotypes (Triticum aestivum L.) differing in nitrogen use efficiency parameters. Journalof Plant Nutrition 33: 1887–1903.

Noulas, C., P. Stamp, A. Soldati, and M. Liedgens. 2004. Nitrogen use efficiency of spring wheat genotypesunder field and lysimeter conditions. Journal of Agronomy and Crop Science 190: 111–118.

Novoa, R., and R. S. Loomis. 1981. Nitrogen and plant production. Plant and Soil 58: 177–204.Ortiz-Monasterio, I. J., K. D. Sayre, S. Rajaram, and M. McMahon. 1997. Genetic progress in wheat yield

and Nitrogen Use Efficiency under four nitrogen rates. Crop Science 37: 898–904.Oscarson, P., T. Lundborg, M. Larsson, and C. M. Larsson. 1995a. Genotypic differences in nitrate

uptake and nitrogen utilization for spring wheat grown hydroponically. Crop Science 35: 1056–1062.

Papakosta, D. K., and A. A. Gagiannas. 1991. Nitrogen dry matter accumulation, remobilization, andlosses for Mediterranean wheat during grain filling. Agronomy Journal 83: 864–870.

Raun, W. R., and G. V. Johnson. 1999. Improving nitrogen use efficiency for cereal production. AgronomyJournal 91: 357–363.

Rroco, E., and K. Mengel. 2000. Nitrogen losses from entire plants of spring wheat (Triticum aestivum)from tillering to maturation. European Journal of Agronomy 13: 101–110.

Sadras, V. O., L. Echarte, and F. H. Andrade. 2000. Profiles of leaf senescence during reproductive growthof sunflower and maize. Annals of Botany 85: 187–195.

Schipper, A. 1991. Modifications of the dough physical properties of various wheat cultivars by environ-mental influences. Agribiological Research 44: 114–132.

Simpson, R. L., H. Lambers, and M. J. Dalling. 1983. Nitrogen redistribution during grain growth inwheat (Triticum aestivum L.). Plant Physiology 71: 7–14.

Slafer, G. A., L. G. Abeledo, D. J. Miralles, F. G. Gonzales, and E. M. Whitechurch. 2001. Photoperiodsensitivity during stem elongation as an avenue to raise potential yield in wheat. Euphytica 119:191–197.

Soil Survey Staff. 2003. Keys to Soil Taxonomy. Washington, DC: U.S. Government, Printing Office.Spiertz, J. H. J., and J. Ellen. 1978. Effects of nitrogen on crop development and grain growth of winter

wheat in relation to the carbohydrate and nitrogen economy of the wheat plant. Netherlands Journalof Agricultural Science 26: 210–231.

Talbert, L. E, S. P. Lanning, R. L. Murphy, and J. M. Martin. 2001. Grain fill duration in twelve hard redspring wheat crosses: genetic variation and association with other agronomic traits. Crop Science 41:1390–1395.

Van Ginkel, M., I. Ortiz-Monasterio, R. Trethowan, and E. Hernandez. 2001. Methodology for selectingsegregating populations for improved N-use efficiency in bread wheat. Euphytica 119: 223–230.

Van Sanford, D. A., and C. T. MacKown. 1987. Cultivar differences in nitrogen remobilization duringgrain fill in soft red winter wheat. Crop Science 27: 295–300.

Vidal, I., L. Longeri, and J. M. Hetier. 1999. Nitrogen uptake and chlorophyll meter measurements inspring wheat. Nutrient Cycling in Agroecosystems 55: 1–6.

Wetselaar, R., and G. D. Farquhar. 1980. Nitrogen losses from tops of plants. Advances in Agronomy 33:263–302.

Dow

nloa

ded

by [

Nag

ref

] at

00:

32 0

8 M

ay 2

013

Course of dry matter and nitrogen accumulation of spring wheat genotypes (Triticum aestivum L.)...

Documents

Transcript of Course of dry matter and nitrogen accumulation of spring wheat genotypes (Triticum aestivum L.)...