Genetic divergence and combining ability in relation to heterosis in Indian mustard [Brassica juncea (L.) Czern. and Coss.] for seed yield, its attributes and oil yield.

摘要

Genetic divergence and combining ability for 9 traits (plant height, days to 50% flowering, days to maturity, primary branches per plant, siliquae per plant, seeds per siliqua, 100-seed weight, seed yield per plant and oil content) of Indian mustard were studied in Imphal, Manipur, India. Genetic divergence studies were conducted during rabi 1999/2000 with 19 all-India released strains/cultivars of Indian mustard. Combining ability studies were conducted during rabi 2000/01 with 7 selected parents and 21 F1s derived via diallel mating design excluding reciprocals. Analysis of variance showed highly significant differences for all traits, indicating a wide range of genetic diversity in the material. Tocher's method grouped the 19 cultivars into 6 clusters, with cluster III recording the most number of genotypes (9). The highest intracluster distance was recorded in cluster III, whereas the highest intercluster distance was observed between cluster II and V. Siliquae per plant had the highest contribution toward total genetic divergence, followed by days to maturity and plant height. Analysis of combining ability revealed that both general (gca) and specific combining ability (sca) variances were highly significant for all traits studied. Varuna, TM-4 and Vardan showed the highest gca effects and yielded crosses with high sca effects for seed yield. In general, parents with low gca effect along with medium divergence had high heterotic cross combinations. On the other hand, medium genetic divergence combined with low or average gca effect resulted in high sca effects and high heterotic performance..