The improvement in sunflower breeding requires exploitation of combining ability of divergent male and female inbreds. Six cytoplasmic male sterile (CMS) lines and three testers were crossed in line ´ tester design, thus 18 F1 hybrids were developed for evaluation of general combining ability (GCA) and specific combining ability (SCA) of inbred parents for days to 90% maturity, stem girth, head size, achenes/plant, 1000-seed weight, achene yield kg/ha, oil and protein%. The significant variances due to lines and testers both determined GCA variances revealed the predominance of additive genes whilst significance of lines ´ tester interactions indicated the importance of SCA variances and the involvement of non-additive genes in the expression of traits studied. The foremost role of non-additive genes was apparent when ratio s2 SCA/s2GCA was above 1.0. These results suggested the prevalence of dominant genes and possibility of hybrid crop development. The GCA effects indicated that CMS parents SF-187, 64-A-93 and ARG-0405 and tester RHP-46 were high general combiners, thus may be chosen for crossing and selection programmes, whereas F1 hybrids SF-187 ´ RHP-46, 64-A-93 ´ RHP-46, PAC-ARG-0405 PAC-ARG-0106, 64-A-93 ´ RHP-46 and PSF-025 ´ RHP-64 which used parents with good ´ good and good ´ poor GCA estimates revealed higher positive SCA estimates for achene yield, oil and protein traits yet manifested desirable negative effects for 90% maturity. Such results suggested that these hybrids are desirable for the exploitation of hybrid crop development or selection of desirable plants from earlier filial generations.
General and Specific Combining Ability Estimates for Morphological, Yield and its Attributes and Seed Traits in Sunflower (Helianthus annuus L.)
