Additive, dominance and epistasis genetic variances were estimated from analysis of a clonally replicated full-sib progeny test grown in the Republic of Congo. Phenotypic variance components were estimated for ages 4 through 25 months for growth and at ages 8 and 18 months for ecophysiological traits. The estimation of genetics effects was derived from the individual mixed model. Genetic structure was incorporated into variances and covariance’s effects based on markers information. The detected genetic effects of epistasis are significant in some traits. This study shows that epistasis variance can be non-zero and contribute significantly to the genetic variability of growth and ecophysiological traits. We conclude that the epistatic effect for quantitative traits may exist, but estimates may not be obtained, either because the models used are inappropriate or because the epistasis variance is too small relative to other components of the genetic variance to be estimated.