This study with the Gardner-Eberhart model (1966) involved eight maize parental populations and their related populations. The objectives were to estimate the cumulative gene effects (additive, dominance and heterotic) which could The justify support of a maize hybrid programo The grain yield inter-varietal dominance effects accounted for 55.54% of the generation means, suggesting large genetic variability within populations. Heterotic effects accounted for 12.11 %, indicating little difference in gene frequency for loci controlling grain yield. Plant height followed the same pattero as grain yield, since dominance effects were the most important. However, homozygote loci (aj) were important in explaining genetic variability for days to bloom and number of ears. For grain yield, the cross Pop. 32 x Pop. 21 maximized the heterotic effects. Population 21 exhibited a high average heterosis, so we suspect that its, combination with Popo 32 and CN(S)-C3, among others, would be a great genetic material for a Reciprocal Recurrent Selection Programo