Epistatic bias and gene action for protein content in green-gram (Phaseolus aureus Roxb.)

Abstract

A study to ascertain the epistatic bias in the estimates of genetic components of variance and sensitivity of the test for epistasis based on the deviation of regression coefficient from unity was conducted. It indicated that the absence of deviation of regression of Wr to Vr from unity is not always a sure test of the absence of epistasis. Graphical, combining ability and variance component analyses suggested the importance of both additive and non-additive components of variance for protein content. The non-additive component of variance was constituted both by dominance and epistatic variance. Predominantly, the epistasis observed, was reinforcing degree of dominance yet, the existence of the one reducing degree of dominance has not been ruled out. High protein content appears to be controlled by dominant genes. Positive (dominant) and negative (recessive) genes were equally frequent and were randomly distributed among the parents. The improvement in this character is possible through accumulation of favourable dominant genes.