Evaluation of bread wheat (Triticum aestivum L.) genotypes for terminal heat tolerance under different environments

Thirty five genetically diverse bread wheat genotypes were evaluated for terminal heat tolerance in three environments by altering the sowing dates viz, non stress (El), mild heat stress (E2) and high heat stress (E3) using physiological indices. Twelve genotypes showed the consistent performance under El and E3 environments. Genotypic performance varied substantially over the El and E3 environments. Genotypes namely, HD 2733, CL 3125, HD 2189, C 306, DBW 14, WR 544, PBW 373, HD 2932, Kundan, HD 2967, HD 2997 and L 512 showed least heat susceptibility index (HSI) for grain yield ranging from 0.1 to 0.5. These genotypes also showed least HSI for other associated characters viz, canopy temperature depression, membrane stability index, 1000 grain weight and biological yield and hence can be regarded as tolerant to terminal heat stress. Since the identified genotypes can cope up the effect of heat stress, they can be utilized for developing heat tolerant genotypes