Assessment of genetic diversity of cotton genotypes for various economic traits against cotton leaf curl disease (CLCuD).

In Pakistan, cotton crop has been under enormous threat of cotton leaf curl disease (CLCuD) over the last four decades. In order to estimate genetic diversity in cotton germplasm CLCuD resistance, we assessed 100 cotton genotypes for their CLCuD resistance/tolerance and other related agronomical traits. Various statistical analytical tools, including correlation analysis, cluster analysis, and principal component analysis (PCA), were used to select the best genotypes. These genotypes can be used in future breeding programs to generate CLCuD resistant varieties. The same set of procedures could be utilized for other diseases in other crops. CLCuD incidence showed a significant negative genotypic correlation with yield-contributing traits followed by a significant negative association for phenotypic correlation. The seed cotton yield showed significant positive genotypic and phenotypic correlations with plant height, number of bolls per plant, and boll weight. From the PCA we identified five principal components (PCs) that explained a significant amount of the variance among the variables, which may be used for selection of cotton genotypes with CLCuD resistance. Of the five PCs, the first four contributed more towards the total variability and had eigenvalues greater than one. The cluster analysis showed that the genotypes in one of the clusters performed particularly well with respect to CLCuD tolerance. These genotypes can be utilized for development of varieties with increased CLCuD tolerance.