Grain growth and yield components of winter wheat cv. Lely were studied in a field experiment in 1976 with 4 rates of N (50, 100, 100 + 50 or 100 + 100 kg N/ha). Growing conditions were characterized by a high level of solar radiation, warmth, ample nutrient supply and no damage by diseases. N raised grain number/m2 from 16 700 to 20 600 and grain yield from 640 to 821 g dry wt./m2. Grain growth duration was short, due to warmth, but the rate of the grain filling was very high (from 24.0 to 29.2 g/m2 day during the effective grain-filling period). A high grain yield was associated with a high grain N content which resulted in a grain protein yield ranging from 63.8 to 107.1 g/m2 with increased N rate from 50 to 200 kg/ha. The carbohydrate demand of the grains was provided by current photosynthesis and relocation of stem reserves. The latter was reflected in a decline of the stem wt. after the mid-kernel filling stage. N and P demands of the grains were supplied by withdrawal from the vegetative organs (leaves, stem, chaff) and to a large extent by post-floral uptake and assimilation. Under the prevailing growing conditions the grains turned out to be very strong sinks for carbohydrate, N and P as shown by the harvest indices. Additional N dressings increased the harvest indices of DN, N and P from 0.40 to 0.48, from 0.75 to 0.81 and from 0.91 to 0.93 resp. It was suggested that a more restricted vegetative crop development at high N levels and a longer duration of root activity, photosynthesis and grain growth after anthesis would considerably favour grain yield. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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Perennial ryegrass cv. Cropper was given high (188), intermediate (140) or low (84 cal/cm2 day between 400-700 nm) light intensity during the period 1 Apr.-30June using supplementary lighting, normal daylight and artificial shading, respectively. Other plots were given 174, 86 and 52 cal/cm2 day during 26 Aug.-1 Oct. and 106, 43 and 26 cal/m2 day until 29 Oct., without affecting the photoperiod. Increased light intensity in autumn or spring considerably increased tillering, while shading treatments gave a decrease. Differences in tiller numbers in autumn decreased during winter and early spring. Numbers of vegetative and reproductive tillers and weight/tiller increased with increasing light intensity in spring. Seed yield was closely correlated with number of reproductive tillers and less closely with number of seeds/head. Supplementary illumination in autumn had only a small effect on number of reproductive tillers but increased number of seeds/head. Maximum LAI of the top 3 leaves, internodes and inflorescences was 13.2, 11.6 and 7.7 in the 3 treatments respectively; these values were high compared with cereals. Amounts of water-soluble carbohydrates in reproductive tillers increased exponentially until ripening and then fell sharply. (Abstract retrieved from CAB Abstracts by CABI’s permission)

A field experiment with 3 cultivars of each of 4 winter cereals (wheat, rye, triticale and barley), sown at about 320 plants/msuperscript 2, was conducted on a fertile clay soil in the central Netherlands. The N fertilizer was split-dressed: 120 kg/ha in total for wheat and triticale, and 60 kg/ha for rye and barley. The fewest shoots/msuperscript 2 were found in triticale (828/msuperscript 2), and the most in barley (1477/msuperscript 2). The average decrease in number of shoots during shoot/ear development was 51% in wheat, 54% in rye, 49% in triticale and 67% in barley. The rate of crop development was largest in rye and barley; they flowered and matured earlier than wheat and triticale. Rye was the first to attain a closed canopy (LAI >3), and had the lowest maximum LAI and shortest leaf area duration. Wheat and triticale stayed green longest. Average specific leaf weight was 4.3 mg/cmsuperscript 2 in wheat and triticale, and 3.7 mg/cmsuperscript 2 in rye and barley. The growth rate of the grains at the linear stage was fastest in barley (1.89 mg grain-1 d-1) and slowest in rye (0.89 mg grain-1 d-1). Total aboveground DM production was 18 790 kg/ha in wheat, 15 230 kg/ha in rye, 18 300 kg/ha in triticale and 12 460 kg/ha in barley. Grain yields (t/ha) were 8.74 (wheat), 6.64 (rye), 8.20 (triticale) and 6.62 (barley). Cultivar differences in grain yield and in yield components were mostly smaller in wheat and rye than in triticale and barley. The harvest index was highest in barley (53.3%) and lowest in rye (43.7%); in some plant species there were marked differences between cultivars, but in others there were not.

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.