Six cytoplasmic male sterile inbred lines and six restorers/testers were selected on the basis of variability for yield related characters. The lines and tester restorers were crossed in a line x tester mating design resulting in 36 F hybrids. The potential parents with high general 1 combining ability (GCA) effects were identified for yield related traits. Among
females, CMS-H55-2-2-1 expressed the highest significant GCA effects for 1000- seed weight whereas female, CMS-303 represented the highest and significant GCA estimates for head diameter, yield and harvest index. Among male parents, RHA-295 expressed the highest significant magnitude for head diameter while SF-187R possessed the highest significant GCA effects for 1000-seed weight, harvest index and moisture contents. Among male parents, the highest
significant value for yield was observed in RHA-854. The potential parent lines with highest GCA estimates can be utilized in different desirable combinations for varietal improvement through breeding programme. The cross of CMS-303 x RHA-271 expressed the highest specific combining ability (SCA) value for yield while CMS 303 x RHA-854 hybrid exhibited the highest SCA estimates for harvest index. CMS-53 x RHA-854 and CMS-64 x SF-187 crosses exhibited the highest SCA estimates for head diameter and 1000-seed weight, respectively. The SCA variances were higher than GCA for seed yield and related traits revealing the involvement of non-additive type of gene action controlling the characters. Estimates of proportional contribution of inbred lines, testers and their inter- action to total variances for seed yield and related traits indicated the highest contribution of lines x testers in inheritance of all characters except harvest index where the contribution of lines was higher than testers and line x testers. Nonadditive type of gene action can be utilized in a hybrid improvement programme through heterosis breeding in sunflower.