Effect of Environment on the Combining Ability of Virginia Tobacco Genotypes

To determine the impact of environment on the combining ability of Virginia tobacco (Nicotiana tabacum L.) five genotypes were crossed in a half diallel fashion and the resulting material was grown under irrigated as well as drought stress conditions. Data collected on yield and related traits revealed highly significant differences among genotypes under both sowing conditions. Combining ability analysis revealed that specific combining ability (sca) were highly significant for all the traits and the general combining ability (gca) effects were highly signification for all the traits except the dry leaf yield both sowing conditions. The results, showed that the additive variance had important role in controlling of number of leaves, width of leaf and leaf area index in both conditions, while, for dry leaf yield, non additive gene effect played major role. In stress conditions, the additive and dominance variances were involved together in plant height, but in non stress condition the dominance variance was more important than additive variance.