MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF COTTON (Gossypium hirsutum L.)
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
The present investigation was carried out during kharif 2017-18 at Regional
Agricultural Research Station, Lam and APGC, Lam, Guntur to characterize 40
genotypes of cotton (G. hirsutum) using DUS characterstics of PPV & FRA and SSR
markers and also to study the variability, heritability, genetic advance as per cent of
mean, and genetic divergence of seed cotton yield per plant and yield component traits.
The data were recorded on 20 descriptors viz., leaf colour, leaf hairiness, leaf
appearance, gossypol glands, leaf nectaries, leaf petiole pigmentation, leaf shape, stem
hairiness, stem pigmentation, bract type, petal colour, petal spot, stigma position, anther
filament colouration, pollen colour, boll bearing habit, boll colour, boll shape, boll
surface, prominence of boll tip and 14 quantitative characters 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), seed index (g), lint index (g), ginning outturn
(%), 2.5% span length (mm), uniformity ratio, micronaire value (10-6 g/inch), bundle
strength (g/tex) and seed cotton yield per plant (g).
The morphological descriptors indicated variability for eight characters (leaf
petiole pigmentation, stem pigmentation, petal colour, stigma position, pollen colour,
boll shape, boll surface, prominence of boll tip) out of twenty characters studied and
these traits are helpful for the identification of the genotypes from one another and some
of the characters like stem hairiness, can be exploited for breeding pest resistant
genotypes.
The genotypic coefficients of variation for all the characters studied were lesser
than the phenotypic coefficients of variation indicating the masking effect of
environment. Wide genetic variability was observed for the characters viz., plant height,
number of sympodia per plant, number of bolls per plant, boll weight and seed cotton
yield per plant. High heritability coupled with high genetic advance as per cent of mean
was recorded for seed cotton yield per plant indicating the preponderance of additive
gene action and hence further improvement may be done through simple selection
procedures.
The results of Mahalanobis D2 analysis indicated the presence of considerable
genetic divergence among the 40 genotypes and the traits bundle strength, days to 50%
flowering, number of monopodia per plant, 2.5% span length and boll weight
contributed maximum towards genetic divergence. The 40 genotypes were grouped into
7 clusters using Tocher’s method indicating genetic diversity and geographical diversity
were not related.
The cluster I had the maximum number of genotypes while the intra-cluster
distance was maximum in the cluster II. The clusters III, IV, V, VI, and VII were
solitary clusters. The inter cluster distance was maximum between clusters II (SCS
1061, CCH 14-2, TSH 0533-1, RS 2767, SCS 1207, L 1008, CCH 14-1, GJHV 510, BS
26) and VI (BS 23) indicating the importance of genotypes present in these clusters in
hybridization programme for the exploitation of heterosis. The cluster II recorded the
highest mean values for the quality traits and seed cotton yield per plant and these
genotypes can be effectively exploited in the breeding programmes.
In the present study, 40 genotypes were also screened with 50 SSR primers out
of which 19 showed polymorphism and the PIC values were also higher for 17 primers
indicating their usefulness in characterization. The jaccard’s similarity coefficient
values ranged from 0.03 to 0.80 indicating that the cultivars have a vast genetic base.
The genotypes, RAH 1033 and L 788 showed least similarity coefficient value among
the genotypes revealing their use in hybridization programme for generating variability
and production of transgressive segregants in the future generations. The genotypes
were grouped into seven clusters using UPGMA method. The cluster I had nine
genotypes while the cluster III was the second largest cluster with 11 genotypes. The
cluster IV was the largest with sixteen genotypes. The clusters II, V, VI and VII were
solitary clusters.
Description
D5596
Keywords
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