Nature of Divergence Among some Varieties of Upland Cotton

Twenty-five varieties of upland cotton (G. hirsutum L.) representing a wide collection of genetic stocks belonging to five different countries were grown in randomized complete blocks with four replications. Analysis of variance revealed significant differences between varieties for all the characters studied— indicating a high degree of variability for different traits related to yield and quality. Plant height, boll number and yield collectively contributed the maximum towards the total divergence. Mahalanobis's D² statistic was used to assess the genetic diversity among the varieties which were grouped into six clusters. The distribution of varieties in different clusters was not according to their geographic origin. The important role of adaptation and selection on divergence was revealed by present study. Utilization of diverse American types and short branched Russian types for hybridization programme is suggested.