Vol. 8, Special Issue 12, Part R (2024)

The magnitude and nature of genetic variability among the genotypes significantly influence the breeding strategies employed. Hence, the present study was carried out to assess the genetic variability and divergence among the twenty eight bread wheat genotypes under two nitrogen conditions: N₀ (no nitrogen) and N⁺ (optimal nitrogen dose). Results revealed that high genotypic and phenotypic coefficients of variation were observed for traits like nitrogen content in leaves and grain yield per plant (in N₀ and N+), leaf chlorophyll content (in N₀) and tillers per plant (in N+), reflecting strong genetic control and minimal environmental influence. Traits such as NUE exhibited high heritability coupled with a high GAM, GCV and PCV, highlighting their reliability for selection under both nitrogen conditions. Cluster analysis indicated wider genetic diversity among wheat genotypes, which were grouped into 7 clusters in N₀ and 10 clusters in N+ condition. Maximum intra cluster distance was observed for cluster IV in both nitrogen conditions. For inter-cluster distances, the largest distance was observed between cluster VI and cluster VII in N₀ condition and between cluster VII and cluster VIII in N+ conditions. Crosses between high-yielding and nitrogen-efficient clusters offer potential for developing heterotic progeny with enhanced traits.