Genetic Analysis of Combining Ability and Gene Action in Sunflower (Helianthus annuus L.) Hybrids through Line × Tester Design

This study was conducted to evaluate the combining ability of six cytoplasmic male sterile (CMS) lines and nine testers using the line × tester method. Biometrical data were recorded for ten agronomic traits: days to 50% flowering, days to maturity, plant height, head diameter, seed filling percentage, 100-seed weight, volume weight, hull content, oil content, and seed yield per plant. The results indicated that specific combining ability (SCA) variance was higher than general combining ability (GCA) variance for most traits, except for days to 50 percent flowering and seed filling percentage, suggesting that non-additive gene action predominantly governed the inheritance of these traits. The GCA of parents did not always align with their per se performance, indicating that GCA should be the primary criterion for selecting parents in breeding programs. Three CMS lines, CMS-103A, CMS-10A and CMS-112A, along with testers EC-75717, EC-502036, EC-279309-1 and R-271-1, were identified as good general combiners for seed yield and yield-contributing traits. Among the hybrids, CMS-243A × EC-279309-1, CMS-243A × EC-75717 and CMS-103A × EC-75717 exhibited the highest SCA effects for seed yield per plant. These findings underscore the importance of selecting superior general combiners for traits like oil content and seed yield to develop high-yielding sunflower hybrids.