Heterosis and combining ability studies in interspecific hybrids (G.hirsutum x G.barbadense) in cotton over environments
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Date
2002
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AAU, Anand
Abstract
The present investigation comprised of 4 genotypes as females, 8 genotypes as males and their 32 resulting interspecific hybrids produced by line x tester mating design. The hybrids alongwith parents were grown in a randomized block design with three replications at the farm of Department of Cytogenetics and Plant Breeding, B.A. College of Agriculture, Gujarat Agricultural University, Anand. The experiment to study heterosis, combining ability and nature of gene action for various yield and quality characters was sown on two different dates during kharif 1999. The analysis of variance, revealed significant differences among the genotypes for the different characters studied indicating sufficient variability in parents. The inconsistency in performance over environments was manifested in the significant genotype x environment interaction for majority of the characters. Considering mean performance, females 4716 SR and G. Cot. 10 gave maximum seed cotton yield and highest measurement for micronaire value, respectively. Among the males, Gujvin, BC 2000-1, Sils 9-22 and 53-56 B proved their superiority for yield, yield attributes and other quality traits. The highest mean performance for seed cotton yield and major yield components was exhibited by the hybrids. Pi x P12 (G. Cot. 10 x Suvin), P1 x P9 (G. Cot. 10 x G. 84-1/247) and P2 x P12 (G. Cot. 16 x Suvin). The highest magnitude of heterosis was observed for halo length followed by number of balls, seed cotton yield, plant height, number of sympods and 2.5% span length. On pooled basis, hybrids P1 x P12 (G. Cot. 10 x Suvin), P2 X P12 (G.Cot.16 x Suvin) and P1 x P9 (G.Cot.lO x G.84-1/247) were the most heterotic crosses for seed cotton yield and other yield attributing characters. For quality characters, none of the hybrids gave the highest magnitude of heterosis. Combining ability analysis indicated the significance of σ2gca and σ2sca sea thereby proving the involvement of additive as well as non-additive gene action. However, the ratio of σ2gca / σ2sca revealed the preponderance of nonadditive gene action for all the characters except halo length on pooled basis. The results on general combining ability effects suggested that female G. Cot. 16 and males Suvin, G. 84-1/247 and 53-56 B were the best general combiner for seed cotton yield and other yield related characters. A direct relationship between gca effects and per se performance indicated the importance of per se performance along with gca effects in selection of parents. Estimates of sea effects did not reveal any specific trend. However, a comparison of sea effects with per se performance of crosses indicated that at least one good general combiner was necessary for better per se performance
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PLANT BREEDING AND GENETICS, AGRICULTURE, A STUDY