GENETIC STUDIES ON RECIPROCAL SELECTION FOR COMBINING ABILITY TO IMPROVE HYBRID PERFORMANCE IN COTTON (Gossypium hirsutum L.)

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dc.contributor.advisorS.A PATIL
dc.contributor.authorSOMASHEKHAR
dc.date.accessioned2019-06-21T04:02:23Z
dc.date.available2019-06-21T04:02:23Z
dc.date.issued2007-08-30
dc.description.abstractHybrid breeding programmes in eross pollinated erops like maize are supported by various schemes for improving combining ability by handling combining ability as a trait. By utilizing such scheme genetically diverse lines are developed, which when used, give rise to superior hybrid combinations, such method can be employed in cotton. The experimental material of this study was constituted by a set of four hirsutum varietal (parental) lines namely RAH 10 (A), RAH 100 (B), RAH20 (C) and RAH200 (D) forming two diverse single (RAHH102 (A X B) and RAHH136 (C x D)) crosses which are found to be veiy diverse from each other based on predicted double eross performance. Twenty six random F4 lines derived from these two single crosses were selected for use in assessing the variability for combining ability. These lines are crossed with three common testers viz., AACHH1065 (T3), 435308 (T4) and ZCH- 21045 (T5). Another two different testers were used as uncommon/reciprocal testers where RAHH136 (Ti) hybrid serves as a tester for evaluating F4 lines of RAHH102 lines and vice versa te., RAHH102 (T2) hybrid serves as a tester for testing combining ability of F4 lines of RAHH136 lines. The magnitude of variability for combining ability was assessed in terms of range, variance, coeflieient of variance and mean seed cotton yield of these derived Fis (26 dFis per tester) in comparison with straight crosses (crosses of parental lines A, B, C and D with tester concerned) and commercial check. By comparing dFis with superior straight crosses, the magnitude of transgressive segregation for combining ability was determined. Efficiency of testers were also determined based on the mean and variances of the derived Fis. Based on this 435308 (T4) was found to be most efficient in distinguishing the F4 lines of the both crosses, A sizeable portion of derived Fis was significantly superior over commercial check. Among F4 lines R-2 (102) (of RAHH 102) and R-5 (136) (of RAHH 136) lines showed highest improvement in combining ability for seed cotton yield and with regard to fibre properties R-1 (136) and R-6 (102) are the potential combiners. Based on weighted per cent gea method R-11 (102), R-18 (102), 1^21 (136) and R-3 (136) F4 lines were found to be potential combiners with higher pooled scores. The SCA variance for seed cotton yield- was high confirming the role of non-additivity including dominance in governing the expression of seed cotton yield. This also confirms the role of dominant favourable alleles in influencing the seed cotton yield. The combining ability status of most productive crosses in this study helped in drawing the inference about handling the best crosses. Apart from sea, gea effects also contributed to superiority of these crosses justifying the emphasis on developing these Fis into commercial hybrids. In general, the correlation between genetic distances through RAPD among parents and the heterosis shown by their hybrids was non-signifieant may be because the molecular markers used to calculate genetic distances are not linked to the genes controlling seed cotton yield.en_US
dc.identifier.otherTH8781
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810109407
dc.language.isoenen_US
dc.pages294en_US
dc.publisherUniversity of Agricultural Sciences GKVK, Bangloreen_US
dc.subGenetics and Plant Breedingen_US
dc.subjectnullen_US
dc.themeGENETIC STUDIES ON RECIPROCAL SELECTION FOR COMBINING ABILITY TO IMPROVE HYBRID PERFORMANCE IN COTTON (Gossypium hirsutum L.)en_US
dc.these.typePh.Den_US
dc.titleGENETIC STUDIES ON RECIPROCAL SELECTION FOR COMBINING ABILITY TO IMPROVE HYBRID PERFORMANCE IN COTTON (Gossypium hirsutum L.)en_US
dc.typeThesisen_US
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