GENETIC DIVERGENCE IN UPLAND COTTON (Gossypium hirsutum L.)
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Date
2015
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Acharya N.G. Ranga Agricultural University, Guntur
Abstract
The present investigation was carried out during Kharif, 2014-15 at Regional Agricultural Research Station, Lam farm, Guntur, Andhra Pradesh to characterize 60 genotypes of cotton (Gossypium hirsutum L.), to study the variability, heritability, genetic advance as per cent of mean, genetic divergence, character association and the magnitude of direct and indirect effects of 15 yield component traits with seed cotton yield per plant viz., plant height, days to 50% flowering, number of monopodia, number of sympodia per plant, number of bolls per plant, boll weight (g), ginning outturn (%), seed index (g), lint index (g), 2.5% span length (mm), micronaire (10-6g/in), bundle strength (g/tex), uniformity ratio, seed cotton yield per plant (g) and lint yield per plant (g).
The genotypic coefficients of variation for all the characters studied were lesser than the phenotypic coefficients of variation indicating the masking effect of the environment. Moderate to high variability and high heritability coupled with high genetic advance as per cent of mean was observed for plant height, number of monopodia per plant, number of bolls per plant, lint index, seed cotton yield per plant and lint yield per plant indicating the predominance of additive gene action and hence, direct phenotypic selection may be useful with respect to these traits.
Correlation study revealed that plant height, number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight, ginning out turn, seed index, lint index and lint yield per plant had positive significant association with seed cotton yield per plant.
The path analysis indicated that plant height, number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight, ginning out turn, seed index, lint index and lint yield per plant showed positive and significant correlation, direct selection based on these attributes may be helpful in evolving high yielding varieties of upland cotton.
The results of multivariate analysis indicated the presence of considerable genetic divergence among the 60 genotypes studied. The 60 genotypes were grouped into 11 clusters in case of D2 analysis indicating that the genetic diversity and geographical diversity were not related.
By Mahalanobi’s D2 statistic, it could be inferred that 2.5% span length, seed index, days to 50% flowering, micronaire, number of monopodia per plant and bundle strength contributed maximum towards genetic divergence. Based on intra-and intercluster distance among the groups, it is suggested to make crosses between the genotypes of cluster IX (HYPS 152) and cluster X (IH 65), between genotypes of cluster IX (HYPS 152) and cluster XI (L 389), between the genotypes of cluster VII (TCH 1705) and cluster XI (L 389), between the genotypes of cluster VIII (GISV 267) and cluster X (IH 65) after confirming their general combining ability.
Principal component analysis identified seven principal components (PCs), which contributed 78.696 per cent of cumulative variance. The significant factors loaded in PC1 towards maximum genetic divergence were plant height, ginning out turn, lint yield per plant, number of bolls per plant, 2.5% span length, seed index, lint index, number of monopodia per plant, days to 50% flowering, seed cotton yield per plant, number of sympodia per plant and boll weight. 2D and 3D graphs showed wide divergence between GISV 267, MCU 5, HYPS 152, TCH 1741, CNH 120 M/B, LH 2256 and IH 65 signifying their usefulness in cotton breeding to develop high heterotic hybrids.
The genotypes HYPS 152, GISV 267, MCU 5, L 389 and TCH 1741 showed maximum inter-cluster distance in Mahalanobi’s D2 analysis, principal component analysis and also have better per se performance in sympodia per plant, number of bolls per plant, boll weight, seed index, lint index and quality characters . So they can be exploited for the development of heterotic hybrids in future breeding programmes.
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D5184
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