Genetic characterization of bread wheat (Triticum aestivum L.) for seed yield and its attributing traits under late sown cropping condition

The present investigation was conducted during rabi 2025 under late sown conditions at the research farm of FASAI, Rama University, Kanpur, to assess genetic variability, association and selection indices for yield improvement in bread wheat (Triticum aestivum L.). A total of 104 diverse genotypes were evaluated in an augmented block design with four checks for thirteen yield and yield-related traits. Analysis of variance revealed highly significant differences among genotypes for all traits, indicating the presence of substantial genetic variability. High heritability coupled with high genetic advance as per cent of mean (GAM) was observed for days to 50% flowering (h² = 96.3%), number of grains per spike (mean 52.88; h² = 91.52%; GAM = 93.92%), grain weight per spike (GCV = 21.26%; h² = 88.31%; GAM = 90.71%), peduncle length (h² = 90.17%; GAM = 92.57%) and test weight (mean 43.22 g; h² = 94.22%; GAM = 96.62%), suggesting predominant additive gene action and effectiveness of direct selection. Grain yield per plant (mean 15.73 g) exhibited moderate heritability (52.75%), indicating influence of both genetic and environmental factors. Correlation analysis revealed that grain yield per plant showed strong positive genotypic associations with test weight (0.902**), grain weight per spike (0.600**), harvest index (0.48**) and effective tillers per plant (0.274**). Number of grains per spike also exhibited a strong positive correlation with grain weight per spike (0.773**), reflecting the importance of sink capacity. Traits such as spikelets per spike and certain phenological traits showed weak or negative associations with yield. Overall, grain weight per spike, number of grains per spike, test weight and effective tillers per plant emerged as major direct yield-contributing traits. These characters, exhibiting high heritability and strong positive association with grain yield, can be effectively utilized as reliable selection indices for developing high-yielding and stable wheat cultivars under late sown conditions.