Grain production and assimilate utilization of wheat in relation to cultivar characteristics, climatic factors and nitrogen supply

The effects on grain production of cultivar characteristics, nitrogen supply and some climatic factors were studied in field trials and under controlled environmental conditions. A rise in temperature considerably increased the rate of grain growth but shortened its duration, whilst the positive effect of light intensity on the grain yield was greater at high temperatures. Additional nitrogen raised post-floral photosynthesis. The nitrogen assimilation by the grains was increased by warmth, resulting in a higher nitrogen concentration of the grains and in earlier senescence of the leaves. Differences between a semi-dwarf cultivar and a standard were mainly expressed in the dry matter distribution before and after anthesis and so in a higher harvest-index.