Mode of gene action in inheritance of vegetative, floral and leaf yield traits in the African eggplant (Solanum aethiopicum)

Understanding gene actions and how they contribute in the expression of characters is of great importance when devising an efficient selection program through the use of a suitable mating design. This study sought to determine the mode of gene action involved in inheritance of vegetative and floral traits in Solanum aethiopicum. Specifically, to establish probable existence of dominance and combining ability of the studied S. aethiopicum genotypes. To do this, twenty-nine (29) successful hybrids from a partial diallel crossing design along with their parental lines were evaluated to determine the mode of gene action involved in inheritance of vegetative, floral and leaf yield traits of S. aethiopicum. A multivariate linear mixed model fit by REML was used to estimate variance components for general combining ability (GCA) and specific combining ability (SCA) in the incomplete diallele design. The specific combining ability (SCA) effects were significant (p>0.01) for all traits measured at 6 and 8 weeks after planting (WAP) except for Harvest Index. Broad-sense heritability (H2) values were generally high (>80%) for all traits compared to narrow sense heritability (h2) at both stages of harvest; moreover Baker’s ratio for these traits was low. The estimates of dominance variance were also higher in magnitude than corresponding estimates of additive variance. The cross N2xN14 had the highest SCA effects for majority of the vegetative traits and floral traits at both 6 and 8WAP. The results showed that non-additive gene action (dominant, additive × dominant and dominant dominant effects) takes centre stage in inheritance of petal colour, stem colour, relative style length, stem hairiness, plant height, number of leaves, plant canopy width, and stem girth, flowers per inflorescence and flowers per plant and harvest index. However, inheritance of leaf area is governed by additive gene action. Therefore, for improvement of the African eggplant, methods such as restricted recurrent selection in early segregating generations might be appropriate. Key words: Combining ability, diallel, gene action, Solanum aethiopicum