Gene effects and combining abilities for 1000-seed mass in sunflower (Helianthus annuus)

Significant differences in the mean values of 1000-seed mass were found among the sunflower (Helianthus annuus L.) genotypes studied (eight inbred lines and 15 F1 hybrids). The mean value of 1000-seed mass was 46.88 g in the female inbreds, 43.52 g in the restorers and 57.45 g in the F1 hybrids. Heterosis and dominance of the better parent manifested themselves in the inheritance of 1000-seed mass in 12 and three combinations, respectively. The nonadditive component of genetic variance played the main role in the inheritance of this trait. The major portion of nonadditive genetic variance was due to superdominance. The inbred lines were found to have different alleles for 1000-seed mass. Standard deviation and coefficient of variation were used as indicators of variability. The influence of genotype and environmental factors and their interactions on total phenotypic variance was determined by the variance analysis model for a two-factorial trial with year as one of the factors. Analysis of phenotypic variance components showed that genotype had the largest contribution in the expression of the trait in the inbreds (78.9%) as well as in F1 hybrids (73.7%). Analysis of combining abilities by the line x tester method (Singh and Choudhary, 1976) revealed that significantly different GCA effects occurred among the inbred lines studied. Inbred lines and F1 hybrids with positive and negative GCA and SCA effects were identified. The inbred lines HA-22 and RHA-C-B were identified as the best general combiners for this trait, and their hybrid combination (NS-H-59) was the only one with a significantly positive SCA value. The GCA/SCA ratio was less than 1. The GCA/SCA showed that the main portion of total genetic variance was nonadditive in character