Terminal heat tolerance in wheat: An overview

Abstract

Since the beginning of the century, ambient temperatures have increased and are predicted to rise further under climate change. Heat stress is a rigorous threat, particularly during reproductive and grain-filling phases, that results into yield loss. Reductions in dry matter accumulation and grain yield, caused by reduced plant photosynthetic capacity through metabolic limitations and oxidative damage to chloroplasts due to heat stress. Wheat pre-breeding and breeding may be based on secondary traits like chlorophyll content, chlorophyll fluorescence and grain number under heat stress. On the other hand, grain yield under heat stress can be improved by selecting genotypes for the rate of grain filling and for grain size. Wheat varieties with improved grain yield can be developed by integrating physiology and biotechnological tools with conventional breeding techniques during reproductive and grain-filling phases. In this review, we have discussed the effect of heat stress on wheat reproductive and grain-filling stages and the strategies to improve terminal heat stress tolerance in wheat.