Genetic divergence studies in American cotton (Gossypium hirsutum L.)

This study aimed to assess the genetic diversity and relationships among the G. hirsutum genotypes using multivariate Mahalanobis D2 statistics. The analysis of variance for dispersion revealed significant differences among the genotypes, which were grouped into five clusters. The largest group, Cluster I, contained 21 genotypes sourced from various locations. Cluster II was the second largest, with 15 genotypes. Clusters III and IV each represented a single genotype, while Cluster V included 2 genotypes and exhibited no intra-cluster D2 value. The trait that contributed most significantly to genetic divergence was seed cotton yield per plant, accounting for 48.32% of the variation. This was followed by halo length (13.21%), number of bolls per plant (8.72%), ginning percentage (5.38%), seed index (4.49%), and number of monopodia per plant (4.23%). The maximum inter-cluster distance between Cluster V and Cluster II was observed, with a D value of 9.33. Therefore, the genotypes in Clusters V and II may be valuable for breeding programs aimed at enhancing heterosis for yield and related traits, such as the number of bolls per plant, boll weight, seed index, seed cotton yield per plant, days to 50% flowering, and days to 50% boll bursting.