Line tester analysis for seed yield and yield components in spring and winter type varieties of oil seed rape

Line × tester analysis of two testers of spring type and six lines of winter type oil seed rape varieties were used to estimate combining ability and heterosis of yield components and seed yield. Significant mean squares of treatments for yield components and seed yield, indicating significant genetic variations among the genotypes including parents and their crosses. Parents vs crosses mean square which indicate average heterosis was significant for all the traits except pods per plant. Line × tester mean square was significant for all the traits except pods per plant. High narrow sense heritability estimate for 1000-seed weight indicating the prime importance of additive genetic effects for this trait. Significant positive general combining ability (GCA) effects of seed yield were observed for parents which had positive GCA effects of pods per plant. Most of the crosses with significant positive specific combining ability (SCA) effects for pods per plant had significant positive SCA effects of seed yield. Most of the crosses had significant positive over spring parent heterosis of seed yield, indicating winter type of oil seed rape varieties are suitable candidates for improving this trait using combination method.   Key words: Heterosis, narrow sense heritability, seed yield, oil seed rape.