The influence of temperature and light intensity on grain growth in relation to the carbohydrate and nitrogen economy of the wheat plant.

Abstract

The response of wheat grain growth to temp. and light intensity was studied under controlled conditions within the ranges 10-25 deg C and 64-188 W/m2, resp. Warmth hastened plant senescence and enhanced the initial growth rate of the grains. Additional light promoted the rate of grain growth more at high than at low temp.; under the latter conditions there was a considerable accumulation of carbohydrates in the stem (up to 40%) from anthesis onwards. The rate of grain growth ranged from 0.70 to 1.64 mg/day grain. The duration of grain growth was prolonged by decrease from 25 to 10 deg ; the increase in growth duration from about 30 to 80 days corresponded with a relatively stable temp. sum. Temp. and light also affected the redistribution of assimilates and the chemical composition of the grain. The rate of protein synthesis was promoted more by warmth than the rate of starch synthesis. This resulted in an increased N content of the grain. The final content of total non-structural carbohydrates (starch and sugars) was slightly decreased by warmth. Additional light raised the carbohydrate content of all parts of the plant and so decreased the N content of these parts. However, light intensity had less effect on N distribution and yield than temp. (Abstract retrieved from CAB Abstracts by CABI’s permission)