TOLERANCE MECHANISM AGAINST IMPACT OF HEAT STRESS ON WHEAT : A REVIEW

Wheat (Triticum aestivum) of the family Poaceae is an important cereal crop and is regarded as a basic source of calories and protein demands of the increasing population. With regards to change in global temperature, the impact of rising temperature on crop production is gaining concern worldwide. Among the various abiotic stresses observed in wheat, heat and drought are the major abiotic stresses. An increase in temperature results in the reduction of grain number, photosynthetic activity, chlorophyll content, and starch synthesis in the endosperm interrupting the important morphological, physiological, and biochemical processes of the plant causing considerable variation like reduction in grain weight per ear, single kernel weight, kernel number, grain size. Spikelet formation, seed size, etc. along with decreased plant size under morphological changes. Similarly, under physiological changes, water potential, photosynthesis, respiration, etc. are adversely affected due to heat stress in wheat. Content of starch, protein, and different types of amino acid present in wheat grain is also affected due to heat stress which comes under biochemical changes. Heat shock proteins (HSPs) and stay green are the mechanisms for the heat tolerance in wheat. The present review was carried out to summarize the various effects of heat stress on wheat at morpho-anatomical, physiological, and biochemical behavior with a brief discussion on suitable breeding strategies to improve the production of wheat crops.