Genetic Divergence of Ashwagandha (Withania somnifera (L.) Dunal) for Growth and Yield Traits

Abstract

Genetic divergence among 32 Ashwagandha (Withania somnifera (L.) Dunal) accessions of different geographic origins was assessed using Mahalanobis D2 statistics. Observations revealed significant genotypic differences, and accordingly, genotypes were classified into six clusters. Cluster I was the largest, with twenty genotypes, followed by the cluster II, which has eight, and clusters III, IV, V, and VI contained only one most divergent genotype. The maximum divergence was observed between clusters II and III (D2 = 47.90), followed by clusters V and VI (D2 = 43.95), and clusters III and VI (D2 = 42.29). Cluster IV had the least inter-cluster distance (D2 = 22.82) with cluster VI. Clusters III, IV, V, and VI had only one genotype each, and hence, the intra-cluster distance was zero. The genotype of cluster V was unique as it had the highest values for fresh and dry root weight per plant, diameter and length of the main root, number of secondary roots per plant, number of berries per plant, and girth of stem with a high seed yield per plant. Cluster VI was desirable in respect of days to 50 per cent flowering and days to root harvest. Cluster II exhibited the highest value for height of plant and branches per plant. Cluster IV had the highest mean values for the number of seeds per berry. Thus, hybridization among these genotypes can generate desirable transgressive segregants. Aim of Studies: To assess the genetic divergen of Withania somnifera. Place and Duration of Study: Department of Horticulture, College of Agriculture, UAS, GKVK, Bengaluru from 2020-21 to 2021-22. Methodology: The genetic divergence between the genotypes in the population was estimated using formula D2= p (Yit - Yjt) and genetic divergence among 32 Ashwagandha (Withania somnifera (L.) Dunal) accessions of different geographic origins was assessed using Mahalanobis D2 statistics. Observations revealed significant genotypic differences, and accordingly. Results: Observations revealed significant genotypic differences, and accordingly, genotypes were classified into six clusters. Cluster I was the largest, with twenty genotypes, followed by the cluster II, which has eight, and clusters III, IV, V, and VI contained only one most divergent genotype. The maximum divergence was observed between clusters II and III (D2 = 47.90), followed by clusters V and VI (D2 = 43.95), and clusters III and VI (D2 = 42.29). Cluster IV had the least inter-cluster distance (D2 = 22.82) with cluster VI. Clusters III, IV, V, and VI had only one genotype each, and hence, the intra-cluster distance was zero. The genotype of cluster V was unique as it had the highest values for fresh and dry root weight per plant, diameter and length of the main root, number of secondary roots per plant, number of berries per plant, and girth of stem with a high seed yield per plant. Cluster VI was desirable in respect of days to 50 per cent flowering and days to root harvest. Cluster II exhibited the highest value for height of plant and branches per plant. Cluster IV had the highest mean values for the number of seeds per berry Conclusion of finding: Significant genetic divergence and complementarity for most features has been shown by the genotypes of clusters II and III and clusters V and VI. This could lead to significant genetic improvement for particular characters and their selection for new varieties.