Nature of gene action for fruit yield and quality charactersof tomato was determined analyzing the mean and variancesof the six genetic populations (P1, P2, F1, F2, BC1 and BC2) ofthree cross combinations involving parental linespossessing mutant genes viz., Alisa Craig AftAftx Alisa Craighp-1 hp-1, Alisa Craig Aft Aftx Alisa Craig ogcogc and AlisaCraig AftAftx BCT 115 dg dg. In most of the characters inthree cross combinations, simple additive / dominance modelwas inadequate to explain the gene action which indicatedthe involvement of epistasis in the control of the characterconcerned. The characters were under the control of bothfixable and non-fixable gene effects, but non-fixable geneeffects were predominant. Duplicate type epistasis for mostof the characters would hinder the pace of progress throughselection. Postponement of selection in later generationsand development of hybrids were the best breeding strategybecause non-fixable gene effects were predominant for mostof the characters.
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