Estimation of genetic variability for Cotton leaf curl virus disease, fiber quality and some morphological traits using multivariate analysis in exotic Gossypium (Diploid and tetraploid) species
This study was designed to evaluate the germplasm imported from USA for cotton leaf curl virus, fiber quality and yield components. Seventy nine cotton genotypes were evaluated using statistical procedures such as correlation analysis, cluster and principle components (PC). These evaluation procedures would result in obtaining parents that possess better tolerance against cotton leaf curl virus and having better fiber quality. Cotton leaf curl virus exhibited a significant negative association with plant height, monopodial and sympodial branches, and a significant positive correlation with fiber fineness but with other traits the relationship was non-significant. The number of days taken to first square has a significant positive correlation with days taken to first flower but a significant negative correlation with GOT and monopodial branches. Principal component (PC) analysis showed the first 4 PCs as having an Eigen value >1 explaining 65.4% of the total variation with CLCuD, plant height and sympodial branches, being the most important characters in PC1. Cluster analysis classified 79 accessions into four divergent groups. The genotypes in cluster 1 showed reasonable values of GOT, staple length and plant height but for other traits selection cannot be made in this cluster. Similarly, the 2nd cluster was comprised of genotypes having low values of fiber fineness and CLCuD and higher values for staple length. The members of the 3rd cluster were characterized by least values of days taken to first square and plant height and more staple length. Cluster 4 was characterized by maximum staple length and boll weight but minimum CLCuD. The genotypes in cluster 1 and 3 may be combined to obtain desirable traits related to earlier and better disease tolerance. Scatter plot and tree diagrams demonstrated sufficient diversity among the cotton accession for various traits and some extent of association between different clusters. The results indicated that the diversity among the genotypes could be utilized for the development of CLCuD resistant varieties with higher seed cotton yield and better fiber quality.