COMBINING ABILITY AND HETEROSIS ANALYSIS IN Brassica rapa

Abstract

An experiment on olciferous Brasski, rapa I.. was conducted to evaluate the combining ability and heterosis of diftbrent characters on seed yield. The mean sum of square due to general combining ability (gca) was significant for plant height. days to 50% flowering, days to maturity and thousand seed weight indicating that the additive gene action was predominant for the expression of these characters. The significant mean sum of square due to specific combining ability (sea) was also observed for plant height, days to maturity. number of primary branches/plant, number of secondary branches/plant, number of siliquae/plant. thousand seed weight and seed yield/plant indicating that the non.additive gene actions were predominant for the expression of these characters. The higher magnitude of gea variance was observed than that of sea variance for plant height. days to 50% flowering. days to maturity, length of siliqua, number of seeds per siliqua and thousand seed weight.The hybrid P, x P10 was found to be the best for number of primary branches per plant. While the cross Pe, x P1 I produced maximum number of secondary branches per plant. The cross P7 x P3 produced maximum number of siliquae per plant. The hybrids P5 x Pin, showed positive heterosis over mid parent and better parent on length of siliqua. thousand seed weight and number of seeds per siliqua. The cross P7 x P1 I showed desirable heterosis for seed yield per plant. The cross P7 x P3. P7 x P10. Pc x Pit and P2 x P11. were also good for seed yield per plant. The parent P5 was good general combiner for days to flowering, maturity and number of seeds per plant. The parent P6 was also good general combiner for number of primary branches, number of siliquae per plant length of siliqua and thousand seed weight. The parent P7 was also good general combiner for number of seeds per siliqua. The parent P10 and P5 were good general combiner for plant height. The parent P10 was good general combiner for number of secondary branches. The hybrids P7 x P11 and P6 x P11 were good specific significant combiner for the number of primary branches. The hybrids P1 x P3. 110 x P3. P5 x P2 and P2 x P10 were good specific combiner for the secondary branches. The hybrids P, x P3. P6 x P3. P5 x 132 and P2 x Plo were good specific combiner for the secondary branches. The hybrids P7 x P3 P7 x P11. P6 x P3. and P5 x P2 have also good sea effects on number of siliquae. The best specific combiner were P, x P11. P6 x Pu. and Ps x 1130 and P2 x P11 for number of seeds per siliqua: P6 x Pit, Ps x P11. P3 x P11 and P2 x P10 also for length of 'siliqua: P7 x P5. P, x P10. 116 x P2 and P6 x PU for thousands seed weight and P5 x P2. P6 x P1. P7 x P;. V7 x Pg and P6 x 113 for seed yield per plant.