Combining Ability in Diallel Cross Analysis Involving Heat Tolerant Lines of Tomato [Lycopersicon esculentum Mill]

The 36 F_1S of tomato obtained from a diallel cross of heat tolerant lines were grown along with parents and check hybrid TH2312, during spring season of 2006. Highly significant GCA and SCA variances observed for different characters except TSS indicated the importance of both additive and non-additive gene action in the expression of these characters. The estimates of component of genetic variance indicated predominant role of non-additive gene effects for the characters studied. Under high temperature conditions EC534-1-2-1 and PS-6-1-1 were best general combiners for most of the traits for instance, endosperm utilization efficiency, setting percentage per cluster, harvesting span, total yield and marketable yield per plant. The cross 1-7-1-1×UC82B was good specific combiner for setting percentage per cluster, days from fruit setting to turning stage, fruit weight, harvesting span, total fruit and marketable yield per plant.