GENETIC DIVERGENCE STUDIES IN COTTON (Gossypium hirsutum L.) FOR YIELD AND YIELD COMPONENTS
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Date
2017
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Publisher
Acharya N.G. Ranga Agricultural University
Abstract
The present investigation was carried out during kharif, 2016-17 at Regional
Agricultural Research Station, Lam farm, Guntur, Andhra Pradesh to characterize 40
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 fifteen yield component traits with seed cotton
yield per plant viz., plant height (cm), days to 50% flowering, number of monopodia per
plant, number of sympodia per plant, number of bolls per plant, boll weight (g), ginning
out-turn (%), seed index (g), lint index (g), 2.5% span length (mm), micronaire (10-
6
g/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. High heritability coupled with moderate genetic advance was
observed in case of micronaire, 2.5% span length and bundle strength revealing
the role of additive and non additive gene action. The other traits viz., number of
monopodia per plant, number of sympodia per plant, number of bolls per plant
and boll weight showed moderate heritability and moderate genetic advance. This
indicates the presence of additive and non-additive gene action and further
improvement of these traits would be possible through heterosis breeding rather
than simple selection.
Correlation study indicated that plant height, days to 50% flowering,
number of sympodia per plant, number of bolls per plant, boll weight, ginning out
turn, seed index, lint index, micronaire, bundle strength, uniformity ratio and lint
yield per plant had positive significant association with seed cotton yield per
plant.
Path coefficient analysis revealed that days to 50% flowering, bundle
strength, number of bolls per plant, number of sympodia per plant, plant height
and number of monopodia per plant exerted highest positive direct effect on seed
cotton yield per plant followed by, ginning out-turn, seed index, lint index and
micronaire. 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 40 genotypes studied. The 40 genotypes were grouped into seven
clusters by using Tocher’s method in D
2
analysis which indicated that the genetic
diversity and geographical diversity were not related.
By Mahalanobis’ D
2
statistic, it could be inferred that seed index, days to 50%
flowering, boll weight, 2.5% span length and micronaire contributed maximum towards
genetic divergence. Based on intra-and inter-cluster distance among the groups, it is
suggested to make crosses between the genotypes of cluster VI (ARBH 1402) and cluster
VII (HYPS 152), between genotypes of cluster I (SSGR 105) and cluster VIII (L 788),
between the genotypes of cluster I (SSGR 105) and cluster IV (L 799), between the
genotypes of cluster V (GJHV 497) and cluster VIII (L 788) after confirming their
general combining ability.
Principal component analysis identified six principal components (PCs) which
contributed 81.99 per cent of cumulative variance. The significant factors loaded in PC1
towards maximum genetic divergence were seed cotton yield per plant, bundle strength,
lint index, micronaire, number of bolls per plant, number of sympodia per plant, plant
height and uniformity ratio. The 2D and 3D graphs showed wide divergence among the
F-2522, TCH-1716, ARBH-1501, HS-296, CPD-1502 and GJHV-517 signifying their
usefulness in cotton breeding to develop high heterotic hybrids.
The fore mentioned six genotypes showed maximum inter-cluster distance in
Mahalanobis’D
2
analysis, principal component analysis and cluster analysis and also for
better performance for number sympodia per plant, number of bolls per plant, boll
weight, seed index, lint index and quality characters. So they could be exploited for the
development of heterotic hybrids in future breeding programmes.
Description
D5429
Keywords
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