Detection of epistasis, additive and dominance variation for some metric traits in Indian mustard under timely and late sown conditions

Sixty progenies were produced by crossing 20 Indian mustard varieties/strains with three testers viz., NDYR 32, Narendra Rai and their F1 (NDYR 32 x Narendra Rai) in a triple test cross fashion to detect epistasis and test of additive and dominance components of genetic variation. Test of epistasis detected important role of epistasis or non-allelic interactions in inheritance of all the characters in both the environments. The additive x additive [i] type of epistatic interaction was significant for silique plant-1 and oil content in normal sown condition (E1) and days to flowering and maturity, secondary branch plant-1, silique plant-1 and seed yield plant-1 under late sown condition (E2). The [j+l] type of epistatic component, representing additive x dominance and dominance x dominance interaction, was significant for all the characters studied. The estimate of fixable additive genetic variance (D) and non-fixable dominance variance (H) were highly significant for all the characters in both the environments. In TTC analysis, the estimates of average degree of dominance indicated over dominance for plant height and oil content in E1 and primary branches per plant in E2.