Estimation of Combining Ability and Gene Action for Agro-Morphological Characters of Rapeseed (Brassica Napus L.) Using Line×Tester Mating Design

Combining ability effects were estimated for different agronomic characters in line × tester crossing program comprising 21 hybrids produced by crossing 7 lines and 3 testers. Parents and hybrids differed significantly for general combining ability (GCA) and specific combining ability (SCA) effects, respectively. The variance due to GCA and SCA showed that gene action was predominantly additive for number of branches. This characters may further be improved through simple selection method in early generation, whereas predominance of non-additive gene action was discovered for plant height, pod per plant and seed yield which are desirable for heterosis breeding and may be exploited in hybrid seed production. Both additive and non-additive genetic constitution were important for seed per pod and thousand kernel weight. Among the 7 female lines, RGS003 revealed maximum GCA effects for seed yield, thousand kernel weight, seed per pod and number of branches. Among the testers, Option500 was desirable as it manifested higher estimates of GCA effects for seed yield and thousand kernel weight. Three cross-combiners Magent × Opera, Elect × Option500 and Shiralee × Opera were found to be the best specific crosses for seed yield