COMBINING ABILITY AND HETEROSIS IN RAPE SEED

Abstract

An experiment on oleiferous Brassica rapa L. was conducted to evaluate the combining ability and heterosis for nine different characters. The parent BAR! sarisha 6 was the best general combiner for plant height, early maturity, number of primary branches, number of siliqua per plant, seed yield per plant and thousand seed weight. The parent BARI sarisha 15 was the best general combiner for number of primary branches per plant and number of seeds per siliqua. The parent Tori 7 was good general combiner for number of secondary branches per plant. The parent SAU sarisha 2 was the best for seed per siliqua. On the basis of avenge score and rank position, Tori 7 X BARI sarisha 15 was the best cross combination for plant height, no. of secondary branches per plant. and no. of siliquae per plant. The combination SAU sarisha 2 X BARI sarisha 15 was the best for days to early maturity. Siliqua length and seed per siliqua. The hybrid SAU sarisha 3 X BARI sarisha 15 was the best for no. of primary branches per plant and thousand seed weight. For seed yield per plant the cross BARI sarisha 6 X BARI sarisha 15 was the best. The higher magnitude of C}CA variance was observed than that of SCA variance for plant height, days to maturity, no. of primary branches/ plant. no. of secondary branches/ plant, no. of siliquae/ plant, seed yield/ plant and 1000 seed weight which indicated the preponderance of additive component in their expression. The Vr-Wr graph indicates over dominance for days to maturity, primary branches per plant, secondary branches per plant, siliquae per plant, and seeds per siliqua. Partial dominance was observed for plant height, length of siliqua, seed yield per plant and thousand seed weight. The graphical analysis also indicated wide genetic diversity among the parents. Out often crosses, the hybrids SAU sarisha 2 X BARI sarisha 6 showed desirable negative heterosis for the character of short plant height. The hybrids SAU sarisha 3 X BARI sarisha 6 were best for early maturity. The hybrids Tori 7 X BARI sarisha 15, SAU sarisha 3 X BARI sarisha15. Tori 7 X SAU sarisha 2 were found to be heterotic for no. of primary branches per plant. no. of secondary branches per plant and no, of siliquae per plant. While the cross Tori 7 X BARI sarisha 15 produced maximum no. of secondary branches and no. of siliquae per plant. Most of the crosses showed significant and negative performance for length of siliqua and no. of seeds per siliqua. The crosses SAU sarisha 2 X BARI sarisha 15 were best for siliqua length and the crosses SAU sarisha 3 X BARI sarisha 6 and Tori 7 X BARI sarisha 6 were best for seeds per siliqua. For thousand seed weight the hybrids SAU sarisha 3 X BARI sarisha 15. Tori 7 X BARI sarisha 15, BARI sarisha 6 X BARI sarisha 15 and Tori 7 X SAU sarisha 2 were best. For seed yield per plant the cross SAU sarisha 2 X BARI sarisha 15 was found to be the best.