Evaluation of selected indian wheat cultivars for identification of tolerant lines under terminal heat stress

In the present study, 102 Indian wheat cultivars were evaluated against terminal heat tolerance under normal and late sowing conditions at the ICAR-NBPGR Farm, New Delhi for two consecutive years in augmented block design. Observations were recorded for ten characters including phenological, yield and yield component traits. Genotype, season, and genotype by season interaction on grain yield and other traits were highly significant. Six genotypes, IC75240(C306); IC75215(PBW34); IC252632(HD2687); IC303070(HD2781); IC75226(WG377); IC75191(DL153-2) were common among the 30 top yielding genotypes across the environments. The Relative Heat Tolerance (RHT) ranged from 0.09% in genotype RAJ3765 (38) to -57.19% in genotype RAJ2184(70). Grain yield was positively correlated with days to spike emergence, days to physiological maturity, biological yield, tillers per plant, grains per spike and harvest index under normal sown condition, whereas it was associated additionally with thousand grain weight under late sown condition. The sufficient genetic variability recorded in the cultivars warrants for improving heat tolerance using combination breeding among these lines and further search for novel variation in untapped genepool.