Combining ability and gene action of some tomato genotypes under low light condition

Limitations in access to electricity in rural areas and substantial cost of supplemental lightning necessitate breeding as response to low light conditions. Seven inbred lines of tomato (Solanum lycopersicum L.) and their F1 hybrids, including reciprocals, developed through a 7×7 full diallel cross were evaluated under two different levels of light. Mean square for light (L) effect was significant for total yield, average fruit weight and days to first flower. Variation attributable to Genotypes and genotype × light (G×L) interaction had significant effect on all studied traits except days to ripening for which G×L interaction was not significant. Diallel analysis across two environments indicated that general (GCA), specific (SCA) and reciprocal combining ability (REC) were significant for all characters implying importance of additive and non-additive gene action along with cytoplasmic effects on genetic expression of yield, yield components and earliness. Ratio of SCA variance to SCA variance and estimates of narrow sense heritability (h2n.s) demonstrated higher weight of additive effects in inheritance of yield, fruit number and days to ripening, while indicating predominance of non-additive effects for fruit weight and early flowering. Interactions GCA×L and SCA×L were significant for almost all studied features. A particular genotype could not be recommended for all traits, but variation among genotypes in response to ambient light was promising for feasibility of plant breeding for non-optimal light intensity and duration