DETECTION OF EPISTASIS AND ESTIMATION OF ADDITIVE AND DOMINANCE COMPONENTS OF GENETIC VARIATION USING TRIPLE TEST CROSS ANALYSIS IN RICE (ORYZA SATIVA L.)

Genetic analyses were performed to uncover the supremacy of additive, dominance and epistasis genetic variances following triple test cross analysis involving three testers (P1, P2 and F1) and four lines of rice. Epistasis was found to be an integral part of genetic variation for days to flowering, plant height, number of tillers per plant and yield per plant. The partitioning of total epistasis revealed that i type (additive x additive) were highly significant for days to flowering whilst j and l type (additive x dominance and dominance x dominance) were important for plant height with predominant effect of i type interaction. j and l type epistasis also played significant role in the inheritance of number of tiller per plant and yield per plant respectively. The additive and dominance effects were highly significant for number of grains per panicle and grain weight per panicle with the exception of 1000-grain weight where dominance effects were non-significant coupled with highly significant additive effects. The degree of dominance was less than unity, indicating partial dominance for number of grains per panicle, grain weight per panicle and 1000-grain weight. The direction of dominance was observed towards less grain weight per panicle. Non-allelic interactions registered for days to flowering, plant height, number of tillers and yield per plant can be manipulated through recurrent selection technique for the improvement of these traits. The predominance of additive gene action for number of grains per panicle, grain weight per panicle and 1000 grain weight suggest that the selection may be delayed to later segregating populations for the improvements of yield through yield components in rice.