HETEROSIS AND COMBINING ABILITY FROM 7X7 DIALLEL ANALYSIS IN Brassica napus L.

Abstract

An experiment on oleiferous Brassica napus L. was conducted to evaluate the heterosis and combining ability for ten different characters. Out of 21 of F1 s, the hybrids Nap2022 x Nap2001 and Nap2022 x Nap248 showed desirable negative heterosis for the characters of shorter plant height, early flowering and early maturity. The hybrid Nap248 x Nap2012 was the best for early flowering. The cross Nap248 Nap 179 was the best for number of primary branches/plant. The hybrid Nap20 13 x Nap94006 was found to be the high heterotic for number of secondary branches and number of siliquae/plant. The cross Nap200l x Nap94006 was the best for siliqua length and number of seeds/siliqua, respectively. For 1000 seed weight the hybrids NapI 79 x Nap200 I and Nap2012 x Nap94006 and for seed yield/plant the crosses Nap2012 x Nap94006 was found to be the best heterotic. The parent Nap-248 was the best general combiner for early flowering, early maturity, plant height. The parent Nap-2012 was the best for 1000 seed weight. For seed yield the parent Nap-179 and Nap-94006 and for number of siliquae/plant the parent. Nap-2022 was suitable general combiner.The parent Nap-94006 is best for high no of primary branches and no of secondary branches. On the basis of average score and rank position, the hybrid Nap2022 x Nap2001 was the best specific combiner for early flowering. The combination Nap200I x Nap94006 was the best specific combiner for number of secondary branches/plant. The cross Nap2022 x Nap94006 and Nap179 x Nap94006 were the best for the number of primary branches and number of siliquae/plant respectively. For siliqua length NapI 79 x Nap94006 was the best specific combiner. The cross Nap20 13 x Nap200 I was the best specific combiner for seed yield/plant and 1000 seed weight. The mean sum of square due to GCA was significant for all traits indicating that the additive gene actions were predominant for the expression of these characters. The significant mean sum of square due to SCA was also observed for all the traits indicating that the non additive gene actions were predominant. The higher magnitude of SCA variance was observed than that of CiCA variance for plant height, days to maturity, number of primary branches, number of secondary branches, number of seeds/siliqua, seed yield/plant and 1000 seed weight.