Effect of post anthesis high temperature stress on growth, physiology and antioxidative defense mechanisms in contrasting wheat genotypes

Abstract

An experiment was conducted to study the effect of post anthesis high temperature stress on morpho-physiological characters, antioxidants and yield of four wheat genotypes. Seeds were sown in the field under normal (15th November) and late sown (15th December) condition. High temperature stress caused significant reduction in photosynthetic parameters, relative water content, membrane stability and chlorophyll content in all the genotypes, with variable magnitude. Activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase increase as a consequence of high temperature conditions. Higher enhancement in activities of antioxidant enzymes under late sown condition was observed in RAJ 4083. There were general reduction in yield and yield contributing parameters but the tolerant genotypes RAJ 4083 and RAJ 4037 maintained higher yield by maintaining relatively higher grain weight and grain number. The effect of high temperature was variable among four wheat genotypes but RAJ 4083 performed the best. It is suggested that heat tolerance of RAJ 4083 could be due to enhanced photosynthetic efficiency, chlorophyll retention, membrane stability and antioxidative defense mechanism under late sown condition. The study also underlines the protective role played by antioxidant enzymes under heat stress and their significance as the basis of the tolerance to high temperature.