The choice of breeding method for genetic improvement of a crop depends on the nature of gene action involved in the expression of its quantitative traits. Hybrid vigour has become a potential tool for genetic improvement of many crops. This study examined heterosis and gene action controlling yield and yield-related traits for selection among eggplant breeding lines. Four breeding lines of Solanum aethiopicum namely: ACN.NH-165; ACN.NH-124; ACN.NH-159; and ACN.NH-125 were crossed using diallel mating design to produce first filial generation without reciprocals. The Ten (four parents and six diallel-cross) families generated were evaluated between July-December, 2014, at the research farm of National Horticultural Research Institute Ibadan, using randomized complete block design with three replications. Data collected on days to 50% flowering, plant height (cm), number of leaves per plant, fruit length (cm), fruit diameter (cm), number of fruits per plant, fruit weight per plant (g) and 1000-seed weight (g) were analyzed for general combining ability (GCA), specific combining ability (SCA) and heterosis estimation. Significant genetic variation was observed among the lines used with respect to all traits evaluated. GCA mean square was significant for all the traits studied, while SCA mean square was significant for all but plant height and number of fruits per plant. Almost all the studied traits had >50% proportion of total genotypic sum of square due to GCA except number of leaves. Heterobeltiosis was observed in ACN.NH-165 × ACN.NH-124 for earliness (-1.15%), 1000-seed weight (21.03%), fruit length (28.50%), fruit diameter (26.65%); and ACN.NH-124 × ACN.NH-125 for number of fruits per plant (7.70%). ACN.NH-124, ACH.NH-165 and ACH.NH-125 which are good combiners in the present study can be used as parents in hybridization breeding program for earliness, higher fruit yield and bigger size of fruits of Solanum aethiopicum.

Keywords: Solanum aethiopicum, heterosis, gene action, diallel