Prediction of Gene Action, Heterosis and Combining Ability to Identify Superior GMS Based Hybrids in Asiatic Cotton (G. arboreum L.)

The nature of gene action and combining ability is valuable in determining whether heterosis is fixable or predictable. Thus, to know the nature of gene action of seed cotton yield and its components and fibre quality parameters, seventeen parents (15 males and two genetic male sterile lines) and 30 F1 crosses (genetic male sterility based) were evaluated in a line x tester mating design of Asiatic cotton (Gossypium arboreum L). Sufficient variability among hybrids and their parents was found as the mean squares of genotypes for all the traits including fibre quality parameters investigated were significant. The total genetic variability was partitioned to general combining ability (GCA) and specific combining ability (SCA) effects. GCA was significant for male parents HD-123, RG-270, CISA-59, CISA-64, CISA-65, CISA-66 and LD-694 for seed cotton yield (SCY); HD-123, RG-286 and DLSA-24 for bolls per plant; HD-123, CISA-59, PAIG-8/3, DLSA-9 and LD-694 for boll weight; female parent DS-5, male parents HD-123, RG-18, CISA-65, and PAIG-8/3 for ginning outturn (GOT%); RG--270, RG-286, PAIG-8/3, DLSA-9 and LD-694 for 2.5% span length (mm); RG-286, CISA-59, CISA-66, PAIG-8/3 and LD-694 for lower micronaire value having finenessand HD-400, RG-270, RG-286, RG-341 CISA-60, CISA-66, PAIG-8/3 and LD-694 for tenacity (g/tex) which were considered as good general combiners. Similarly among 30 cross combinations, SCA was positively significant for 10 crosses for seed cotton yield, 10 crosses for boll number, 10 crosses for boll weight, 9 crosses for GOT(%), 10 crosses for 2.5% span length and 8 crosses for fibre strength (gt/tex).Cluster III of yield attributing traits, consisted of 9 crosses ( C3, C6, C18, C20, C26, C22, C23, C24, C30, and C8) showed the highest average seed cotton yield where as Cluster II of fibre quality traits consisted of 3 crosses ( C2, C12, C15) showed highest average GOT(%) with highest tenacity (g/tex). Cross DS-5 x HD 123for SCY and bolls per plant, DS-5 x DLSA 9 for boll weight, DS-5 x CISA 65 for GOT % , CISA-2 x CISA 66 for lower micronaire value (fibre fineness) showed significant estimation of heterosis in desirable direction and could be further utilized in the future breeding programme for specific trait improvement.