Effect of high temperature stress on growth, biomass and yield of wheat genotypes

Twenty four wheat genotypes were sown under normal and late sown irrigated conditions. Under late planting crop was exposed to high temperature during anthesis and grain filling stages. High temperature stress caused significant reductions in physiological parameters and yield. High temperature/late sowing induced decline in membrane stability index (31.1%), plant height (17.1%), biomass (39.2%) and seed yield (51.7%) were observed in WH 730, HI 1535, WH 896 and RR 3, respectively. Genotypes LOK-1, HI-1418, DL-788-2, Raj-3765 showed lower values of heat susceptibility index (<0.5) and higher values of yield stability index (>90%), and therefore grouped as temperature tolerant. Membrane stability index at seed development stage showed positive association with biomass and seed yield in wheat genotypes under normal and late sown conditions. The linear relationship of MSI with seed yield and biological yield showed dependence of seed yield and biomass on membrane stability index.