Assessment of genetic diversity for terminal heat tolerance in bread wheat (Triticum aestivum L. em. Thell.) under very late sown condition

Abstract

Heat stress in wheat bears very high significance in realsing yield potential of a genotype. Terminal heat stress in particular affects the wheat yields considerably. Keeping this in view the present investigation was carried out with 32 diverse genotypes of bread wheat in completely randomized block design with 3 replications at G.B. Pant University of agriculture & Technology, Pantnagar for studying the genetic diversity for terminal heat stress tolerance under very late sown condition. The observations were recorded on 16 agronomic traits and 3 physiological traits. The statistical analysis for genetic divergence wasdoneusingMahalanobis-D 2 statisticsandclusteringofgenotypeswasdoneusingTochermethod.On the basis of genetic diversity analysis, it was found that grain yield/plot and minimum by CTD-IV. Clustering of genotypes revealed that cluster-III had maximum number of genotype followed by cluster-I,cluster-II,cluster-IV,cluster-Vandcluster-VI.Thehighestinter-clusterdistancewasobservedbetween cluster-IV and VI while lowest inter-cluster distance was observed between cluster-I and II. The highest intra-cluster distance was observed in cluster-III revealing maximum genetic divergence among its constituents while lowest intra-cluster distance was observed in cluster-VI. The five genotypes were found tolerant to heat stress. The genotypes bearing desired values from different clusters can beexploited in future breeding programme for improving the yield and physiological traits under very late sown condition for mitigating the threat of terminal heat stress in bread wheat.