Genetic Divergence in Indian Mustard [brassica Juncea (L.) Czern and Coss] under Sub-Himalayan Region.

A study was carried out with 71 genotypes of Indian mustard [Brassica juncea (L.) Czern and Coss] under sub-Himalayan condition to examine the genetic diversity within them. All the 71 genotypes were tested in randomized complete block design with three replications during rabi 2017-18. The genetic divergence was studied among the genotypes of Indian mustard [Brassica juncea (L.) Czern & Coss] using Mahalanobis D2 statistics followed by Rao (1952). Genotypes were found to be grouped into seven clusters. Cluster I had the largest number of genotypes (31) followed by cluster IV (21), V (12), II (two), III (two), VI (two) and VII (one). Maximum intra cluster divergence was found in cluster VI followed by cluster V, IV and I. Maximum inter cluster distance was found between cluster VII and V followed by cluster VII and VI, cluster VII and IV and cluster VII and I, which indicates that efficient breeding programme can be formulated to improve yield potential by hybridization between genotypes from these clusters. Based on the maximum intra cluster distance value the crosses could be made among the genotypes having the highest divergence like PHR-2, RNWR-09-3, Giriraj, Kranti, SKJM-05, DRMR-15-16, RW-85-59 and NPJ-194 from various clusters like IV, V, VI and VII to get desirable transgressive segregants. Cluster III having the highest seed yield (11.80 g plant-1) had not shown highest genetic divergence from the other clusters. However, other clusters like cluster IV, V, VI, and VII had shown higher genetic divergence among themselves. Plant height (18.71) contributed maximum towards genetic divergence followed by 1000 seed weight (18.35) as well as penetration force (18.35), aphid count (12.76) and seed yield per plant (10.62). For the characters like plant height,1000 seed weight, penetration force, seed yield and aphid count contributing substantially high to the total genetic divergence, it was found that genetically divergent clusters namely IV, V, VI and VII performed optimally and amongst these clusters only. Cluster VII was the poorest seed yielder. This clearly reflected that the genetically divergent genotypes were distributed in the different clusters like cluster IV, V, VI and VII.