Combining ability and heterotic studies through line × tester in local and exotic upland cotton genotypes

Combining ability is mostly used by breeders to select appropriate parental cultivars to produce the larger progeny of new combinations through their hybridization. the objectives of this research were to estimate general combining ability of parents and specific combining abilities of f1 hybrids,to identify suitable parents and hybrids for yield and its contributing traits,fiber quality parameters and also determine the heterosis in f1 populations. in this study,35 f1 hybrids obtained by crossing five local lines (turkey) with seven exotic testers (usa,pakistan,greece and israel) in line × tester mating system during 2008 and were planted in randomized complete block design with four replications during 2009. analysis revealed significant gca and sca mean squares for all the traits,however,non-additive gene action was predominant. among parents,sahin 2000 and tamcot-22 were the best general combiners for yield and its components,and carmen was the best general combiner for improvement in fiber quality. the best specific combinations were s-2000 × sj-u86 and gsn-12 × niab-999 for boll number; ba-119 × dpl90 for boll weight; s-2000 × niab-999 for seed cotton yield; gsn-12 × eva for fiber length; gsn-12 × az-31 and ba-119 × tamcot-22 for fiber strength. in f1 hybrids,the highest heterosis was observed for yield,boll number,boll weight and lint % with values of 79.8,19.8,35.2,and 5.7%,respectively. heterosis values for fiber quality parameters were generally lower than that for yield components and 14.1% heterosis was observed for micronaire. the f1 hybrids viz; sahin-2000 × tamcot-22,sahin-2000 × niab-999,carmen × tamcot-22,and carmen × niab-999 were noticed as high yielding hybrids with acceptable fiber quality parameters. results also indicated that identification and selection of best new f1 hybrids should not be only based on gca and sca,but it must be coupled with mean performance.