Characterization, diversity studies and clustering of tetraploid Bt cotton hybrids using morphological markers

摘要

A study was conducted to characterise the Bt cotton hybrids and their parents using morphological markers as given by test guidelines of DUS in cotton. Among the 26 characters, nine characters viz., hypocotyl pigmentation, gossypol glands, nectaries,petiole pigmentation, stem pigmentation, bract type, boll colour, boll bearing habit and boll opening were not included in this Principal Component (PC) analysis since they had no variability. The PCA revealed that the first eight PCs having Eigen values> 1 and explained 78.22 per cent of the total variation. The variance explained by PCI was mostly due to traits related to colour traits like boll surface, leaf shape, growth habit, petal spot, stigma, petal colour and boll prominence of tip whereas PCII was mostly related to seed fuzz colour, anther filament colouration, leaf appearance and petal colour. Two dimensional scatter plots supported the grouping patterns of cluster analysis. Cluster analysis classified 60 genotypes into three distinct clusters. The cluster I was the largest comprising of 38 genotypes followed by cluster III occupies 17 genotypes and cluster II consists of five genotypes. The genotypes in cluster I is mainly contributed by petal spot and anther filament colouration, cluster II by petal spot, semi digitate leaf shape and pitted boll surface and cluster III having yellow petal colour. So these genotypes are very much useful for crop improvement.