WHEAT GENOTYPES RESPONSE TO HEAT STRESS TOLERANCE NORMAL AND DELAY SOWING DATES

At average physical maturity, flag leaf area, specific flag leaf weight, grain spike-1, grain weight spike-1, 1000-grain weight, grain yield plant-1, organic yield plant-1, crop index, relative water content and cell membrane stability showed a decrease of 7.01, 31.38, 20.63, 20.50, 37.93, 30.63, 37.87, 31.62, 9.38, 16.95 and 10.96%, respectively, under heat stress conditions.While the wheat genotypes like Imdad-05, NIA-Sarang and TD-1 showed minimum reductions under heat stress conditions for various traits suggesting their heat tolerance, nonetheless cultivars Khirman and AS-2002 expressed maximum declines under heat stress expressing their susceptibility to heat stress conditions. Chlorophyll fluorescence changes, changes in cell membrane permeability, changes in canopy temperature, etc. after high temperature stress are used as physiological indicators for heat resistance screening and evaluation, especially cell membranes. Delay heat stress is the reason for the shortening of the grain filling period. [...]improper grain filling will affect the total yield of wheat crops (Khokhar et al., 2019a). [...]the delay sown wheat crop faced terminal heat stress.