GENE ACTION AND COMBINING ABILITY IN SOME TOMATO (Solanum lycopersicum L.) CROSSES GROWN IN LATE SUMMER SEASON

Gene action and combining ability effects were estimated in forty five hybrids obtained from crossing fifteen lines with three testers using line x tester matting design. These genotypes (fifteen lines, three testers and forty five hybrids) were evaluated for vegetative growth, yield and its quality in late summer season. This study was carried out at Faculty of Agriculture, KafrelsheikhUniversity, Sidi Salim distrect, North-Delta Region of Egypt. G.C.A and P.C.V. % ranged from 0.88 to 0.98, which was confirmed by the estimated ratio of G.C.V. / P.C.V. Furthermore, broad sense heritability (h2bs) values ranged from 76.96 to 95.60 suggesting less effect of environmental and the large portion of σ2p was due to the σ2g on these traits. The magnitude of variance due to general and specific combining ability was highly significant indicating importance of the additive (σ2A) and non-additive (σ2D) gene action. However, the ratios of σ2GCA / σ2SCA (<1) and σ2A/ σ2D (<1) revealed the preponderance of non-additive variance in the inheritance of all studied traits. The average degree of dominance revealed over-dominance for all studied traits except for ascorbic acid content, which was revealed partial dominance. Highly significant differences were observed among the parents and hybrids for general combining ability (GCA) and specific combining ability (SCA) effects. The parental lines HE-13-2-1, HE-6-5-1, HE-13-1-1 and D-7-3-1 displayed desirable general combiners for most studied traits. The cross combinations HE-13-1-1 x F.M.9, D-4-3-1 x F.M.9, D-2-1-2 x Super Strain B and HE-19-1-1 x Super Strain B are considered the best specific combinations since showed desirable significant SCA effect values for most studied traits.