Combining ability analysis for quality and nutritional traits in rice

Combining ability analysis was carried out with seven parents and twenty one F1s in diallel mating without reciprocals for their quality and nutritional traits. The results indicated that the sca variance was greater than gca variance for all the characters under study except for milling percentage and protein content indicating that the trait was under the influence of non-additive gene action. Significant values of mean squares for both gca and sca for all the quality characters indicated considerable influence of both additive and non-additive variances. Non-additive gene action was predominant in governing the protein, iron and zinc contents as the ratio of gca variance to total variance was low. The results indicated that there was close relationship between mean performance of the parents and their gca effects in most of the cases studied. Based on gca effects Indra was the best parent among all the seven parents studied as it recorded positive gca effects for hulling, milling, head rice recovery, L/B ratio and grain yield per plant. The characters viz L/B ratio, volume expansion ratio, amylose, iron and zinc contents are predominantly governed by non-additive gene action. However the role of additive component of gene action appears to be considerable along with non-additive effect in case of head rice recovery, L/B ratio and elongation ratio.