Information on gene actions controlling the expression of traits from generation mean analysis is critical for developing heterotic hybrids and/or selection of lines from segregating generations. The study was conducted under irrigation condition at West Wallega Zone Gimbi Destric from October 2020 to June 2021. Two extremely different lines viz. ARP tomato d2 (Floradado) (fresh market tomato) with higher TSS, pH value, sugar-acid ratio, and titratable acidity) and Roma VF (processing tomato with lower TSS, pH value, This research is therefore, conducted to estimate the type of gene actions and interactions and to assess the gene actions and interactions involved in the expression of yield and yield related traits. The inheritance of days to flowering is governed by simple additive-dominance genetic system predominantly under negative significant influence of dominance gene effect. Therefore, hybrid breeding could be applied to develop early maturing variety in tomato. Highly significant all type digenic and complex digenic interaction was observed for days to maturity, plant height, fruit per plant, shape index and fruit weight. This indicated that the inheritance of these traits is controlled by higher order interactions or complex higher order interactions or under the influence of complex genetic control or they have large environmental variance.

Keywords: Additive-dominance, Digenic-interaction, Scaling test, non-allelic interaction, epistatic interactions