Quantitative Trait Variation and Identification of Key Yield Components in Bread Wheat Genotypes under Eastern Indo-Gangetic Plains

A field evaluation of 298 bread wheat (Triticum aestivum L.) genotypes was conducted under timely sown conditions at ANDUAT, Kumarganj, Ayodhya, to quantify genetic variability, heritability, and trait associations influencing grain yield. Analysis of variance revealed highly significant genotypic differences across 12 quantitative traits. Phenotypic coefficient of variation (PCV) consistently exceeded genotypic coefficient of variation (GCV), indicating environmental modulation. Traits such as economic yield, grain number per spike, and tillers per plant exhibited high broad-sense heritability (h²b) with substantial genetic advance as a percentage of the mean (GAM), suggesting predominance of additive gene action. Correlation analysis demonstrated strong positive associations of grain yield with grains per spike (0.805), biological yield (0.530), 1000-grain weight, and harvest index. Path coefficient analysis partitioned these correlations into direct and indirect effects, revealing grain number per spike (direct effect = 0.8869), biological yield (0.5359), and harvest index (0.5787) as principal determinants of yield. Negative direct effects were observed for days to maturity, plant height, and anthesis. Indirect effects through interrelated traits further modulated yield components, with a low residual effect (0.143), confirming model adequacy. The results underscore the strategic importance of selecting for grain number per spike, biological yield, and harvest index to enhance yield potential in wheat breeding programs.