Heterosis and Combining Ability for Ornamental Traits in Petunia (Petunia hybrida Hort.) Inbred Lines

In order to evaluate the heterosis and combining ability of petunia inbred lines for ornamental traits, 12 hybrids were derived from direct and reciprocal crosses of 4 petunia inbred lines viz. L5 (P1), L8 (P2), L11 (P3), and L17 (P4). In the second year, the derived hybrids and their parents were planted in a randomized complete block design with three replications. The measured traits in F1 generation were, plant height at first flower, number of flower per plant, days to flowering, flower diameter, flower tube diameter, flower tube length, flower length, flower longevity and flower fragrance. The significance of specific combining ability (SCA) and general combining ability (GCA) for the most studied traits revealed that both additive and non-additive gene effects contributed to the inheritance of the traits. Not statistically significant of GCA/SCA ratio and the degree of dominance more than one showed that the contribution of non-additive gene actions was relatively higher than that of additive for all studied traits. For flower diameter, parent P2 and hybrid P1 × P2 had the highest GCA and SCA effects, respectively. Reciprocal effects were significant in all measured traits except for flower longevity and flower length. Estimation of heterosis showed that combinations P1 × P3 and P2 × P3 had the highest heterosis relative to mid and high parents for flower number and diameter among all hybrid combinations, respectively.