The effect of temperature on kernel development in cereals

Abstract

A study has been made of the effect of temperature on kernel development and mature kernel weight of three contrasting cereals: wheat, rice and sorghum.

Wheat and sorghum showed clear and well-separated optimum temperatures for individual kernel dry weights of 15/10° and 27/22°C respectively, while rice showed a relatively small change in weight over temperatures ranging from 21/16° to 30/25°. Rice kernel development was less affected by temperature extremes than sorghum, but was more sensitive to low temperature than wheat. At the lower temperatures (21/16°) the rate of development of individual kernels was greater in wheat than in the other species, while in sorghum, which had a more marked temperature response, the rate of kernel development was greater than in the other cereals at the higher temperatures (30/25°). A preliminary analysis of barley suggests that kernel development in this cereal responds to temperature in a similar way to wheat.

Measurements of net photosynthesis of the flag leaf blade and ear of each cereal, at intervals after anthesis, suggested that at the completion of kernel development a source of carbohydrate was still available for continued development at all temperatures. A preliminary examination was carried out on the role of respiration and of translocation in limiting kernel development at high temperatures.