Physiology of heat and drought tolerance in wheat: An overview

Abstract

Wheat crop often gets exposed to drought and high temperature during grain growth particularly in subtropical conditions. Physiology of wheat is adversely affected by heat stress and drought stress. Heat and drought tolerance are influenced by some of the physiological traits such as increased rates of photosynthesis, stay green, chlorophyll concentration, chlorophyll fluorescence, and so on. Under drought stress wheat yield is mostly decreased by half or less of the irrigated control. Drought stress (60% relative soil moisture content) has been found to decrease the grain yield by more reduction in the kernel weight than the grain. Hence, any efforts to improve grain yield of wheat under these stresses should consider insights into the mechanisms of grain development and also the physiological traits when plants experience terminal stress. For improvement of grain weight of wheat under abiotic stress conditions caused by drought and high temperature found that drought stress decreased the grain yield per spike by 16.2% in the tolerant cultivar and by 27.9% in sensitive cultivar. But under combined heat and drought stress, the same cultivar did not show high tolerance. High temperature significantly reduced the grain weight and number of grains in wheat. Some other studies have reported that post anthesis rise in ambient temperature resulted in reduction in individual grain weight. So, it can be concluded that for the sustainability of the agriculture heat stress and drought are the major barrier in the field.