Genetic divergence studies in cluster bean genotypes

The present experiments were carried out at Department of Horticulture, Dr. PDKV, Akola and Regional Research Centre, Amravati during the years 2013-14 and 2014-15. Fifty five genotypes of cluster bean were assessed for genetic divergence using Mahalanobis D2 technique. Among the characters studied in all four environmental conditions, gum content in seed (63.50%), plant spread (17.17%), number of primary branches per plant (4.65%), days to first flower (3.77%), hundred seed weight (2.09%), days to 50 % flowering(1.95%), seed to husk ratio (1.68%) and ten dry pod weight (1.35%) contributed 95 percent to the total divergence. Genotypes were grouped into 8 clusters using Tocher’s method. Cluster V was the largest group, involving 17 genotypes followed by twelve genotypes were grouped in cluster IV, eleven genotypes in cluster III and six genotype each in cluster I and II. The remaining solitary clusters (VI, VII and VIII) contained only one genotype each. The genotypes from the solitary clusters showed high divergence and useful in breeding. The intra-cluster distance ranged from 0 to 9.15. Cluster V possessed the highest intra-cluster distance (D2=9.15), followed by cluster IV (D2=6.34), cluster III (D2=4.71), cluster II (D2=3.31), and cluster I (D2=2.65). The clusters comprised of only one genotype had zero intra-cluster distance (cluster VI to VIII). The average inter-cluster distance reveled  the maximum divergence(D²) between cluster V and VIII (D²=37.26) followed by cluster III and V (D²=29.92), cluster VI and VIII (D²=25.51). On the basis of inter cluster distance and performance observed in the present study a breeding programme involving genotypes for a specific character has been selected using cluster mean.