Ontogenic Changes in Growth and Assimilate Distribution as Influenced by N Supply in Rapeseed-mustard

Brassica juncea , cv. Pusa Bold, and Brassica campestris , cv. Pusa Kalyani, were raised under field conditions with varying levels of N fertilization, i.e. 0, 40, 80 and 120 kg N ha⁻¹. Changes in dry matter accumulation in various plant parts as influenced by N supply were measured throughout the crop ontogeny. N supply up to 120 kg had an increasing effect on the growth of leaves, stem and pods during the entire period till maturity. Analysis on the assimilate distribution pattern revealed that 84–87% of the total was accumulated during the post-flowering phase. Dry matter partitioning profile during the ontogeny indicated that about 72–83 % of the total DM was accumulated in the leaves, while 17–28 % in the stem, in the preflowering phase. This trend was found nearly opposite during the postflowering phase. At maturity, however, stem and pods accounted for nearly equal amounts of dry matter accumulation. Among the genotypes, Pusa Bold recorded significantly higher DM accumulation and seed yield over Pusa Kalyani which, on the other hand, exhibited a better assimilate-partioning ability than the former. Nitrogen levels had a favourable effect on LAI, LAD and CGR in both genotypes. Highly significant correlations were obtained between seed yield vs. LAI, LAD and CGR. N fertilization up to 120 kg ha⁻¹ was found beneficial in enhancing growth and yield of rapeseed-mustard.     

Response of Mustard to Ethrel Spray and Basal and Foliar Application of Nitrogen

In a field trial conducted during 1992–93 and 1993–94, the effect of basal (B) nitrogen (N) (45 and 60 kg N ha⁻¹) and foliar application (F) of water (W) or 10 kg N ha⁻¹ and 400 or 600 ppm ethrel (E) (2-Chloro ethyl phosphonic acid) at 70 days after sowing was studied on leaf area index and dry mass at 90 days and pod number per plant, seeds per pod, 1000 seed weight, seed yield, oil content and oil vield at harvest of mustard ( Brassica juncea L. Czern & Coss.) cv. T-59. Recommended basal (B) application of 90 kg N ha (BN₉₀) was used as control. On the basis of 2 year data it was found that basal application of 60 kg N and foliar spray of 10 kg N ha ⁻¹ and 600 ppm ethrel gave higher values for growth and yield characteristics and enhanced seed yield and oil yield by 12.5 and 14.8%, respectively over control BN_90.     

Contribution of Leaf Photosynthesis towards Seed Yield in Brassica species

The effect of defoliation after flowering, when a considerable number of pods were already formed on yield components, was examined in four Brassica species. In B. campestris and B. juncea , a decrease in seed yield by defoliation was associated with a decrease in the number of pods per plant as seed number per pod and thousand-seed weight were not significantly affected by this treatment. In B. nigra , apart from decreasing the pod number per plant, defoliation also significantly decreased the thousand-seed weight, Defoliation significantly decreased both seed number per pod and thousand-seed weight apart from decreasing the number of pods per plant in B. carinata. The study indicated that in B. campestris and B. juncea , the role of leaf photosynthesis seemed to be restricted mainly to the formation of pods. On the other hand, in B. nigra and B. carinata it appeared that leaf photosynthesis also contributed towards seed development.     

不同氮肥用量对绿豆主要农艺性状及产量的影响

为确定陕西榆林风沙草滩地区绿豆种植的最佳氮肥施用量,以‘榆绿1号’为试验对象,设计6个氮肥施用梯度,研究不同氮肥用量对绿豆植物学性状、经济性状和产量的影响。试验结果表明：不同氮肥用量对绿豆株高、主茎分枝数、百粒重和产量达到了差异显著的影响,对主茎节数、荚长、单株荚数和单荚粒数的影响差异不显著。由氮肥施用量和产量的回归方程得出,在施用P₂O₅ 60 kg/hm²、K₂O 45 kg/hm²和商品有机肥750 kg/hm²的基础上,氮肥最佳施用量推荐为75 kg/hm²。     

Effect of Gibberellic Acid Spray and Basal Nitrogen and Phosphorus on Productivity and Fatty Acid Composition of Rapeseed-Mustard

Two field experiments were conducted during] 994-95 to study the effect of spray of 10⁻⁵ M GA3 at 40 days after sowing on mustard ( Brassica juncea (L.) Czern & Coss.) cv. Varuna grown with basally applied 0, 40, 80 and 120 kg N ha⁻¹ (Expt. 1) and 0,15, 30 and 45 kg P ha⁻¹ (Expt. 2) on pod number per plant, seeds per pod, 1000 seed weight, seed yield, biological yield, harvest index and fatty acid composition of oil. No significant difference between water and GA3 spray was found when basally applied nitrogen was 0 or 40 kg N ha⁻¹. N₈₀ proved to be the best for yield characteristics. In another experiment on phosphorus, GA₃ and 30 kg P ha⁻¹ individually enhanced the yield, but interaction of GA₃ and P remained non-significant. The fatty acid composition of oil in both experiments was significantly affected only by nitrogen and phosphorus treatments for oleic acid and erucic acid. It was found that return in the form of yield was more for every kg applied fertilizer under GA, spray treatment. The response was more for N fertilizer in comparison to P. GA₃ at a low level of fertilization significantly increased the return from fertilization.     

密度对红豆草农艺性状和种子产量的影响

为了合理利用空间资源,提高红豆草种子产量,试验以奇台红豆草为材料,设置不同的种植密度,通过对株高、分枝数、荚果数、千粒重、种子产量等指标的测量,探寻密度与红豆草生殖格局的关系。试验结果表明,种植密度30 cm×25 cm时,单株花序数、荚果数、千粒重和种子产量最高,依次是81.1个、839.2个、23.8 g、1995.8 kg/hm²。通过相关性分析,种子产量与千粒重呈显著正相关,相关系数为0.631;种子产量与单株荚果数呈极显著正相关,相关系数高达0.998。     

The Effect of Nitrogen Fertilization and Population Density of the Field Bean (Vicia faba L. minor) of Indeterminate and Determinate Growth Habit on the Symbiosis with Root Nodule Bacteria and on the Seed Yield

Field beans of indeterminate (cv. Nadwiślański) and determinate (cv. Tibo) growth habits were grown on field plots with a density of 20, 40 and 80 plants m⁻² at two levels of nitrogen fertilization: low (20 kg N ha⁻¹) and very high (150 kg N ha⁻¹). At the phase of intense pod growth the number and the dry matter weight of root nodules as well as their nitrogenase activity and some features of the plants growth were determined, and in the period of ripeness the components of seed yield were established.
It was found that increased density of sowing as well as the high level of nitrogen fertilization inhibited the growth and development of root nodules and limited their nitrogenase activity in both cultivars. Plants of both varieties were characterized by a similar potential of forming the root nodules, however, in plants of the cv. Tibo the nitrogenase activity of nodules was much lower than in the cv. Nadwiślański.
Increased population density of the plants has in both varieties given increased seed yield when calculated per m² of the soil, compensating in excess the depression of the seed yield from one plant. Such compensation did not occur in the case of the depression of nitrogen fixation under intense nitrogen fertilization.     

Response of Rainfed Sunflower (Helianthus annuus L.) to Nitrogen Rates and Plant Population in the Semi-arid Savanna Region of Nigeria

Field experiments were conducted during the wet seasons of 1991,1992 and 1993 at the Abubakar Tafawa Balewa University Farm, Bauchi (10 ° 22'N, 09 ° 47'E) to study the response of sunflower ( Helianthus annaus L.) to N rates and plant population under rainfed conditions. Four N rates (0, 50, 100 and 150 kg N ha ^-1) and four plant populations (40000,80000,120000 and 160000 plants ha^-1) were factorially combined in a randomized complete block design with three replications. Leaf area index, shoot dry weight and seed yield (kg ha^-1) increased significantly with increasing N rates from 0 to 100 kg N ha^-1. The growth and yield parameters per plant decreased significantly with increasing plant populations from 40000 to 160000 plants ha^-1, but the seed yield (kg ha^-1) obtained at 80000 plants ha^-1 was significantly higher than all the other plant populations. The interactions of N x plant population confounded the main effect of each factor on the growth and yield of sunflower. The seed yield (3425 kg ha^-1) obtained from the use of 100 kg N ha^-1 at 80000 plants ha^-1 was significantly higher than those obtained from all other combinations of N x population and out-yielded the main effects of 100 kg N ha^-1 and 80000 plants ha^-1 by 18 % and 25 %, respectively. The use of 100 kg N ha^-1 at 80000 plants ha^-1 is therefore recommended for maximum yield of sunflower in Bauchi.     

Response of Mustard (Brassica juncea L.) to Applied Nitrogen with or without Ethrel Spray under Non-irrigated Conditions

Field studies were conducted during the winter seasons of 1995–96 and 1996–97 at the Agricultural Farm of Aligarh Muslim University, Aligarh, India on mustard ( Brassica juncea L. Czern & Coss., var. Alankar) under non-irrigated conditions, to evaluate the effect of foliar spray of 200 p.p.m. ethrel (2-chloroethyl phosphonic acid) at flowering growth stage along with basal 0, 40, 80 or 120 kg N ha⁻¹ on net photosynthetic rate (P_N), stomatal conductance (C_S), stomatal resistance (R_S), leaf K content, relative water content (RWC), leaf area index (LAI) and total dry matter (TDM) production monitored at 20 days after spray application, and plant N content, seed N content, nitrogen harvest index (NHI), nitrogen yield merit (NYM), pods plant⁻¹, 1000 seed weight, seed yield, biological yield, harvest index (HI), seed yield merit (SYM) and merit of genotype (MOG) at harvest. Results indicated that, at 0 or 40 kg N ha⁻¹, ethrel did not produce any significance effect, but at basal 80 kg N ha⁻¹, ethrel affected the parameters favourably with the exception of 1000 seed weight, HI, seed N and NHI. Ethrel-sprayed plants utilized N from the soil more effectively and showed increased NYM. Yield attributes, seed yield and merit of genotype (in terms of NYM and SYM) were also enhanced. Ethrel spray enhanced seed yield under water stress conditions mainly by increasing K uptake and retaining higher RWC, thereby decreasing R_S and increasing LAI, P_N and TDM production.     

The Influence of Row Spacing and Seeding Rate on Seed Yield and Yield Components of Forage Turnip (Brassica rapa L.)

The effects of four row spacings (17.5, 35.0, 52.5 and 70.0 cm) and five seeding rates (50, 100, 200, 400 and 800 viable seeds m^?2) on seed yield and some yield components of forage turnip (Brassica rapa L.) were evaluated under rainfed conditions in Bursa, Turkey in the 1998–1999 and 1999–2000 growing seasons. Plant height, stem diameter, pods/terminal raceme, total pods/plant, seeds/pod and primary branches/plant were measured individually. The number of plants per unit area was counted and the lodging rate of the plots was scored. The seed yield and 1000‐seed weight were also determined. Row spacing and seeding rate significantly affected most yield components measured. The number of plants per unit area increased with increasing seeding rate and decreasing row spacing. Plant height was not greatly influenced by row spacing and seeding rate, but higher seeding rates reduced the number of primary branches and the stem diameter. The number of pods/main stem was affected by row spacing and but not by the seeding rate. Also, the number of seeds per pod was not affected by either the row spacing or the seeding rate. In contrast, the number of pods per plant clearly increased with increasing row spacing, but decreased with increasing seeding rate. The plots seeded at narrow row spacings and at high seeding rates were more sensitive to lodging. Seeding rate had no significant effect on seed yield in both years. Seed yield was similar at all seeding rates, averaging 1151 kg ha^?1. However, row spacing was associated with seed yield. The highest seed yield (1409 kg ha^?1) was obtained for the 35.0‐cm row spacing and 200 seeds m^?2 seeding rate combination without serious lodging problems.     

Effect of Gibberellic Acid Spray during Ontogeny of Mustard on Growth, Nutrient Uptake and Yield Characteristics

In a field trial conducted during 1993–1994, mustard ( Brassica juncea L. Czern & Coss.) cv. Varuna was sprayed with either deionised water or 10⁻⁵ M GA₃ at 40 (vegetative stage), 60 (flowering stage) or 80 (pod fill stage) days after sowing (DAS) to select the suitable growth stage for spray for augmenting productivity of the crop. Shoot length per plant, leaf number per plant, leaf area per plant, dry weight per plant and leaf area index and accumulation of N, P and K were recorded at 100 DAS. Pods per plant, seeds per pod, 1000 seed weight, seed yield, biological yield, harvest index and seed yield merit were computed at harvest. Growth, NPK accumulation and yield were maximal when spraying was done at 40 DAS. However, spraying at 40 and 60 DAS gave at par values for most of the growth and yield parameters. It was also noted that there was a significant difference in spray treatment at different growth stages only when G A, was sprayed and not when water was sprayed.     

Effects of Irrigation at Different Growth Stages and Source-Sink Manipulations on Yield and Yield Components of Mung Bean, Vigna radiata (L.) Wilczek, in Dry and Intermediate Zones of Sri Lanka

Irrigation is a management option available to farmers in the subhumid zones of Sri Lanka to increase mung bean yields during the dry Yala season. The objective of this study was to quantify the yield gain in response to irrigation at different stages of the crop and thereby determine the most suitable stage/s of irrigation. Four field experiments were conducted during Yala in 1995 and 1996 at two sites, Maha-Illuppallama (MI) and Kundasale (KS). Eight irrigation regimes consisting of all possible combinations of irrigation at three growth stages of the crop were defined. The respective growth stages were vegetative (from germination to appearance of first flower), flowering (from appearance of first flower to 75 % pod initiation) and pod-filling (from 75 % pod initiation to maturity). The treatments which received irrigation during two or more stages had significantly higher yields (793–1396 kg ha⁻¹) than those which received irrigation during only one stage (401–756 kg ha⁻¹) with the lowest yield being shown by the rain-fed treatment (227–396 kg ha⁻¹). When at least two stages can be irrigated, irrigation during the flowering and pod-filling stages was most effective. Irrigation during flowering produced the highest yield gain when only one stage could be irrigated. Seed yield showed a strong positive correlation with number of pods m^−2. Fifity per cent de-podding caused yield reductions at both sites, indicating sink limitation. In contrast, 50 % defoliation reduced the yields only at MI where the number of pods m⁻² was greater than at KS. Hence, source limitation was present only when the number of pods was higher.     

Effects of Timing of Drought Stress on Phenology, Yield and Yield Components of Short-duration Pigeonpea

Nine short-duration pigeonpea genotypes were given adequate soil moisture throughout growth or subjected to water stress during the late vegetative and flowering (stress 1), flowering and early pod development (stress 2), or podfill (stress 3) growth stages under field conditions. The stress 1 treatment had no significant effect on the time to flowering. No stress treatment affected maturity or inter-plant flowering synchronization. The interval from a newly opened flower to a mature pod was about 30 days for all genotypes, and was unchanged in plants that were recovenng from stress 1 or undergoing stress 2. Seed yield was reduced to the greatest extent by stress 2 (by 37 %) and not significantly affected by stress 3 for all genotypes. No consistent differences were found between determinate and indeterminate genotypes in the ability to maintain seed yield under both stress 1 and stress 2. The harvest index was significantly reduced (22 %) by stress 2 but not by stress 1. However, under each soil moisture treatment, genotypic differences for seed yield were associated largely with differences in total dry matter production (TDM). For all genotypes, the number of pods m^-2 was the only yield component significantly affected by the water stress treatments. The stability of other yield components should be fully exploited to improve the stability of seed yield under drought conditions (drought resistance). Possible characteristics which may improve the drought resistance of short-duration pigeonpea include the ability to maintain TDM, low flowering synchronization, small pod size with few seeds pod^-1, and large 100-seed mass.     

Effect of Integration of Fertilizer and Green Manure Nitrogen on Yield Attributes, Nitrogen Uptake and Yield of Lowland Rice (Oryza sativa L.)

Field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, India, during the wet seasons of 1992 and 1993 to study the effect of full and partial substitution of fertiliser N with green manure N (Sesbania rostrata) on nitrogen uptake, yield attributes and yield of rice. The experiment consisted of eight treatments with two levels of N (100 and 200 kg ha⁻¹) and three sources of N application viz., fertilizer, integrated (1:1 fertilizer and green manure N) and green manure N compared to the recommended practice (150 kg fertilizer plus 6.25 t ha⁻¹ (72 kg N) green manure) and a no N control. Nitrogen application markedly increased the N uptake. Combined use of the two N sources at 200 and 222 kg N ha⁻¹ and of single fertilizer N at 200 kg N ha⁻¹ recorded the maximum N uptake, increased the yield attributes such as number of panicles per unit area, weight per panicle, number of total and filled grains per panicle and test weight. At 200 kg N ha⁻¹ full substitution of N by green manure reduced the grain yield but only partial substitution of N by green manure resulted in almost similar yield as single fertilizer N. Thus 200 kg N ha⁻¹ applied in equal proportions of fertilizer and green manure N can be recommended for medium duration rice cultivars.     

Optimum Seed Rate and Nitrogen Fertilizer Requirement of Rice Under Semi-deepwater Ecosystem

The effect of varying seed rates (100–1000 seeds m⁻²) and nitrogen fertilizer (0–60 kg N ha_-1) applied either in a single basal dose or in splits was investigated on a tall elongating, photosensitive rice variety, Nalini, under semi-deepwater conditions (0–100cm) during 1993 and 1994 at Cuttack, India. Seedling emergence was higher in 1993 (53.9 %) than in 1994 (44.1 %) and it increased proportionately with increasing seed rate, Increase in the number of tillers and panicles m⁻² at higher seed rates was associated with a corresponding decrease in panicle weight. Regression analysis indicated a decrease of 0.91–1.28g in panicle weight for an increase of 100 panicles m⁻². The grain yield of rice was significantly higher at 400 seeds m⁻² in 1993 and at 600 seeds m⁻² in 1994 than at low seed rates but further increase in seed rate did not increase the yield. Application of N fertilizer increased the panicle number and thereby grain yield significantly. The effect of basal and split applied N at active or maximum tillering stages as well as between 30 and 60 kg N ha⁻¹ was not significant on the grain yield. The results suggest that a basal dose of 30kg N ha⁻¹ and seeding density of 400–600 seeds m⁻², resulting in 40–50 % seedling emergence and 150–200 panicles m⁻², each with 2.0–2.5 g weight, may be adequate for optimum productivity of rice under semideepwater conditions.     

Growth and Yield Responses to Plant Density and Stage of Transplanting in Winter Oilseed Rape (Brassica napus L.)

Growth and yield responses to plant density (6.75 × 10⁴, 9.75 × 10⁴ and 12.75 × 10⁴ plants ha^–1) and stage of transplanting (30, 35 and 40 days after sowing) of winter oilseed rape cultivar HO 605 were investigated in two field trials in the 1996/97 and 1997/98 growing seasons at Zhejiang University Farm, Huajiachi Campus, China. Results revealed a progressive decrease in leaf area per plant in response to increasing plant density and delayed transplanting, though leaf area m^–2 and leaf area index were higher in high-density plants. Number of effective branches and pod per branch decreased with increasing plant density and delayed transplanting. There were no significant differences in the mean seed weight among treatments. Although the average number of seeds per pod was significantly lower for high-density plants and delayed transplanting, the economically highest seed yields were realized in relatively high-density plants. Seed oil content was negatively affected by increasing plant density, but no significant differences were observed with delayed transplanting. The highest seed yields of 1730.7 and 1748.1 kg ha^–1 with no significant differences were observed for plant densities of 9.75 × 10⁴ and 12.75 × 10⁴ plants ha^–1, respectively, transplanted at 35 and 30 days after sowing.     

Effect of Inoculant Rate on Nodulation and Various Agronomic Traits of Soybean

In a soil lacking indigenous Bradyrhizobium japonicum , soybean ( Glycine max [L.] Merr.) nodulation depends upon the number of rhizobia applied with the inoculum. This field study reports the effect of different rates of applied rhizobia on nodulation, dry matter and nitrogen content in soybean in a Mediterranean soil lacking B. japonicum.
Treatments included six rates of B. japonicum , ranging from 2.5 × 10⁴ to 6.075 × 10⁶ rhizobia cells per seed applied to the seed as peat inoculant at planting, 100 kg N ha⁻¹ and an uninoculated control. The experiment was conducted in an Entisol soil. Regression analysis showed linear relationship between the rate of applied rhizobia and the number of the nodules per plant or the dry weight per nodule. In early stages of development (32 and 68 days after planting) plant dry weight was not affected by inoculation rate. At harvest a rate of 7.5 × 10⁴ rhizobia cells per seed was necessary for maximum total and stover dry weight. A higher rate, 6.75 × 10⁵ rhizobia cells per seed, was required to obtain maximum grain yield, total N content in plant tops and grain N content. Grain percentage N was increased up to 2.025 × 10⁶ rhizobia cells per seed. Nitrogen application increased grain yield, total N content and grain N content at the same level as the lower inoculation rate.     

Genetic analyses of agronomic and seed quality traits of doubled haploid population in Brassica napus through microspore culture

Summary The results showed that the F1 genotype from the cross (Brassica napus cv. Zheshuang 758 × cv. Z-4115) had good response to embryogenesis, and their embryo yield and rate of plant regeneration reached 69.8 embryo/bud and 46.9%, respectively. Characters from the doubled haploid (DH) populations in B. napus were analyzed and it was showed that the means of each agronomic trait were between their parents, but they were nearer to the paternal in 6 agronomic traits (plant height, branch position, number of pods in the main raceme, length of pod, number of pods/plant and number of seeds/pod). The number of genes controlling each agronomic trait was analyzed based on the DH populations. The results showed that the number of genes controlling number of pods in the main raceme was the highest (15.6), and the least number of genes was involved for stem width (only 7.9). According to estimated coefficients of skewness and kurtosis of the traits tested, gene interaction was found to be absent for stem width, plant height, length of main raceme, number of primary and secondary branches, pod density in the main raceme and seed weight/plant. Complementary interaction was also observed in five agronomic traits (number of pods in the main raceme, length of pod, number of pods/plant, number of seeds/pod and 1000-seed weight). A significantly positive correlation was observed between seed yield/plant and four agronomic traits (length of main raceme, length of pod, number of pods/plant and 1000-seed weight). The experiment also showed that the erucic acid, glucosinolate, oil and protein contents of DH populations were 34.23%, 87.09 μmol/g, 44.09% and 42.67%, respectively. The numbers of genes controlling each quality trait were 7.8, 9.7, 9.4 and 8.7, respectively. Partial correlations between the seed quality traits and the agronomic characters of DH populations were analyzed. In this experiment, the partial correlations among seed quality traits were also analyzed and it was found that the oil content had a negative correlation with the other three seed quality traits.     

Effect of Okra Planting Density and Spatial Arrangement in Intercrop with Maize on the Growth and Yield of the Component Species

The effects of three okra planting densities (28 000; 56 000 and 111 000 plants ha¹) intercropped within or between maize rows were investigated in two field trials during the 1990 and 1991 wet seasons at Nsukka. The plant height and the leaf area index (LAI) increased as the planting density increased in sole or intercropped okra while the number of branches per plant decreased with increasing okra planting density. The height of maize plants also increased as okra planting density increased but the LAI decreased. Intercropping reduced the yield and yield components (number and weight of pods per plant) of okra and maize (number of cobs, cob length and 100-grain weight). Increasing okra planting density reduced the sole and the intercropped okra and also the maize intercrop yield by reducing the number of pods and grains as well as the pod and grain size, respectively. Assessment of the productivity ofthe mixtures showed that the highest yield advantage (35%) of growing okra and maize together was obtained at 28000 okra plants ha¹ while the highest monetary return was realized at the highest okra planting density of 111000 plants ha¹ intercropped between maize rows. The patterns of row arrangement did not have effect on the growth, yield and yield components of the mixtures.     

Effects of Nitrogen and Plant Density on Growth, Yield and Chemical Composition of Two Winter Wheat (Triticum aestivum L.) Cultivars

A field study was conducted on the winter wheat cultivars Arminda and Okapi , using two seed rates (80 and 160 kg/ha) and three N applications (40, 80 and 120 kg/ha).
The cultivars did not differ in total dry matter production but did differ in grain yield. The difference in grain yield was mainly attributable to a higher harvest index (HI).
Increased plant density reduced HI; it resulted in more shoots per m², but in a lower grain yield. The reduction in grain yield was caused by fewer kernels per ear and a lower 1000-grain weight in both cultivars.
A higher rate of N increased total dry matter production and grain yield, except in Okapi at the high plant density. The number of kernels per ear increased, but 1000-grain weight fell.
The higher the N applications, the higher the N-content of the roots was.
Total N yield was greater in Arminda than in Okapi. The cultivars differed in the amount of nitrogen they took up after anthesis.
The content of water-soluble carbohydrates (WSC) differed between the cultivars, N treatments and growth stages. Carbohydrate formed before anthesis accounted for 23 % of Arminda's grain yield and for 10 % of Okapi's grain yield.
The content of cell-wall constituents (CWC) depended on cultivar, growth stage and the rate of the N dressing. Differences in CWC were more pronounced in Arminda than in Okapi. During leaf, stem and ear development there was a strong increase in content and amount of CWC. Concomitantly, WSC decreased. This implies that a large consumption of WSC is necessary for the formation of CWC. The competition for the WSC, necessary for CWC and shoot and ear development influences kernel initiation. Per unit of dry matter Okapi contained more CWC than Arminda. This was not in agreement with differences in straw sturdiness.