Combining ability through line × tester analysis for phenological, seed yield, and oil traits in sunflower (Helianthus annuus L.)

Abstract

Major improvement in sunflower breeding requires heterotic hybrids which can be achieved by tapping combining ability of F1 hybrids developed from crossing of two genetically diverse female lines with male testers. Six lines and three testers were crossed in a line × tester mating design, thus 18 F1 hybrids were developed for genetic analysis. The objectives of this research were (i) to determine combining ability of female and male lines through line × tester analysis for developing rewarding sunflower hybrids and (ii) to estimate additive and non-additive genes controlling phenological, seed yield and oil traits. The experiment was carried-out in randomized complete block design with four replications. The combined analysis revealed that genotypes performed differently over the years for all the characters with the exception of leaves per plant and 1,000-achene weight, however genotypes × year interactions were non-significant for all the traits except plant height. The non-significant interactions hence indicated that the genotypes were quite consistent in the performance over the years. The significant differences (p < 0.01) among the parents, crosses and parents versus crosses were also observed. The significant mean squares due to lines and testers both determine the general combining ability (GCA) revealed the prevalence of additive variances and additive genes influencing the traits. While the significance of lines × tester interactions indicated the importance of specific combining ability (SCA) of parents and demonstrated the importance dominance or non-additive variances and genes. The major role of dominant genes was found because the degree of dominance was greater than unity. These results indicated the preponderance of dominant gene action and the feasibility of hybrid sunflower development. GCA estimates revealed that female lines HO-I, T-4-0319 and PAC-0505 and testers PAC-0306 and PAC-64-A were good general combiners for early maturity, seed yield and oil content. SCA estimates determined the suitability of F1 hybrids and the hybrids T-4-0319 × SF-187, HO-I × PAC-0306, Peshawar-93 × SF-187 manifested higher positive SCA effects for seed yield and oil content while they recorded negative but desirable SCA effects for phenological traits and plant height.