Decreasing level of genetic diversity in germplasm and cultivars of upland cotton (Gossypium hirsutum) in Pakistan
2012
Ahmad, M.Q. (University of Agriculture, Faisalabad (Pakistan). Dept. of Plant Breeding and Genetics) | Khan, S.H. (University of Agriculture, Faisalabad (Pakistan). Centre of Agricultural Biochemistry and Biotechnology) | Azhar, F.M. (University of Agriculture, Faisalabad (Pakistan). Dept. of Plant Breeding and Genetics)
This study was conducted to investigate the level of diversity among cotton germplasm before and after year 1975 in Pakistan. Principal component analysis and cluster analysis was carried out on phenotypic data of 16 characters. As revealed through PCA, pre-1975 group showed 41% genetic diversity, while post-1975 cultivars accounted for 37% genetic diversity. 1st principal component being the most diverse component accounted 1-53% of degree of association in pre-1975 as compared to 1-46% in post-1975 cultivars. Number of days to boll open, fiber fineness, number of locules, internodal distance and ginning out turn percentage were noted as the characteristics that showed maximum diversity among exotic germplasm. In score plot analysis, entries in pre-1975 group scattered, while modern cultivars being similar were present very close to each other. Cluster analysis grouped all 39 accessions into five clusters on similarity bases. Cultivars in the post-1975 group were present in the same cluster showing that current breeding efforts had narrowed the genetic basis of upland cotton in Pakistan.
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