Assessment of Terminal Heat Stress Tolerance in Doubled Haploids Derived from Synthetic Hexaploid Wheat (Triticum aestivum L.) Using Genetic Variability and PCA-based Cluster Analyses

A comprehensive study was conducted on germplasm derived from two synthetic wheats and two hexaploid wheats i.e., SHW14102 x BWL4444, SHW14102 x BWL3531, and SHW3761 x BWL4444 to identify the potential doubled haploids that can withstand high temperatures, particularly at the reproductive stage during crop seasons viz., 2020–2021 and 2021–2022. The doubled haploid lines were selected based on phenotypic characteristics using genetic variability analysis. In the preliminary field trial evaluation, 100 lines were selected based on high phenotypic uniformity for further testing against terminal heat stress conditions and high yield potential. Among these, 17 lines had relatively higher values for days to biomass yield, grain yield, thousand-grain weight, and harvest index and relatively lower values for maturity, and grain filling duration based on principal component and cluster analyses. Principal component analysis (PCA) based cluster analysis exhibited that, clusters II and III had clear separation compared to cluster I. All three clusters were analyzed according to their means and standard deviations. The mean values for GYP (385.07), BMYP (1162.37), and TGW (38.13) were relatively higher in cluster 1 than in other clusters. Cluster 2 exhibited a higher value for DH (89.14), SL with awns (18.21), and GFD (18.19) while cluster 3 showed a higher value for HI (41.02). Thus, it was concluded that cluster I demonstrated superior performance in grain yield per plant, biomass yield per plant, and thousand-grain weight, indicating its overall higher productivity compared to the other clusters under terminal heat stress conditions and suggesting them as potential germplasm for future breeding programs.