Genetic diversity for seed cotton yield parameters, protein and oil contents among various Bt. cotton cultivars

Availability of sufficient genetic diversity is prerequisite for selection of economically important traits. Forty upland cotton genotypes were evaluated for genetic variability with respect to seed cotton yield attributes, fiber quality traits and protein and oil content in the seed through PCA and cluster analysis. Considerable genetic differences were estimated among the genotypes for most of the characters including bolls per plant, seed cotton yield, lint percentage, oil content, protein content and fiber uniformity while non-significant results were recorded for boll weight, fiber length, fiber strength and fiber fineness. Phenotypic variances were a little higher than genotypic variances for all the traits except bolls per plant and seed cotton yield for which environmental variance was higher indicating more influence of environmental factors. Heritability in broad sense was high for all the traits except bolls per plant and seed cotton yield. Genetic advance was the highest for seed cotton yield (31.50) followed by bolls per plant (13.77), fiber uniformity (9.26) and crude protein (8.97). Correlation analysis revealed the highest significant correlation between seed cotton yield and bolls per plant (0.858) followed by seed cotton yield and fiber fineness (0.469). Oil and protein contents were negatively correlated. Principal component analysis (PCA) revealed four PCs exhibiting Eigen value more than 1and contributing 66.1% in total variability. Dendrogram showed that the clusters I and II were the most diverse clusters indicating that their members had great genetic diversity for the characters under study. Genotypes belonging to distant clusters may be used for exploiting the maximum genetic diversity.