Membrane thermostability and chlorophyll fluorescence as indices of high temperature stress tolerance and performance in wheat ( Triticum aestivum L.)

An experiment was conducted for the measurement of membrane thermostability and chlorophyll fluorescence in parents and their six F 1 ’s at post-anthesis stage. Parents and F 1 ’s showed significant variation for high temperature stress tolerance in late sown conditions. Genotype PBW 435 and the cross PBW 343 × PBW 435 exhibited less relative injury and greater thermotolerance possibly through maintaining cellular membrane integrity under high temperature stress. Data based on chlorophyll fluorescence revealed reduction of mean values of all genotypes and their F 1 ’s for F v /F m , proportion of efficiently working Photo system II (PSII) units among the total PS II population in late sown conditions. The genotypes EIGN 8, UP 2425 and Raj 3765 and F 1 s EIGN 8 × UP 2425 and PBW 343 × WH 283 figured important for further wheat improvement programmes