Relating Phenotypic and Molecular Diversity with Heterosis in Cotton (Gossypium hirsutum L.)
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Date
2011
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Publisher
UAS, Dharwad
Abstract
The study was mainly aimed at assessing diversity among hirsutum varieties
both at phenotypic (D2 analysis) and molecular level (SSR based) and relating this
diversity with actual heterosis observed in a set of crosses involving representative set
of parents.
A set of 156 hirsutum lines was subjected to D2 analysis based on different
plant type, productivity and fibre quality parameters. Most of the robust and compact
types figured in first two clusters. Among the parents utilized for developing
Line×Tester analysis, D2 values ranged from 12.92 to 505.02 and highest D2 value was
noticed between RAH-35 and RAH-13-86 which were used as tester and line
respectively. The combination (RAH-370×RAH-110) with lowest D2 value exhibited
low yield of 2122.41 kg/ha. The highest seed cotton yield (4117.50 kg/ha) was
exhibited in the cross RAH-53×RAH-10 with D2 values of 128.74, while next best
cross (RAH-13-86×RAH-35) revealed highest D2 value in this study.
These most productive crosses were characterized based on combining ability
effects and the method of handling of these crosses was inferred based on this. SCA
variance was higher in magnitude than GCA variance for majority of characters.
Correlation co-efficient values were determined between D2 value, similarity
co-efficient values and heterosis for seed cotton yield. The correlation value were
positive and significant at both phenotypic (r=0.762) and molecular level (r=0.828)
indicating a positive relationship between diversity and heterosis. However, this needs
to be confirmed based on larger set of markers.
The association among quantitative characters was studied at phenotypic (rP),
genotypic (rG) and genetic (rA) levels. The genetic correlation values differed in
magnitude as well as direction from genotypic and phenotypic correlation suggesting
importance of working out genetic correlations. At the level of breeding value, seed
cotton yield exhibited highest positive genetic correlation with number of bolls per
plant (rA=0.45), boll weight (rA=0.21) and other traits.
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Keywords
Genetics and Plant Breeding