Exploring genetic variability and trait relationships in Ashwagandha (Withania somnifera Dunal L.) for improved yield

Abstract

This study estimated genetic variability and interrelationship among traits in 50 genotypes of Indian Ashwagandha, with the objective of identifying superior genotypes for improvement. Significant differences (p < 0.01) among genotypes were observed for 12 morphological and yield-related traits. High heritability estimates (>90 %) were coupled with high genetic advance as % of the mean (>40 %) for most traits. The highest genotypic and phenotypic coefficients of variation (106.143 % and 106.548 % respectively) and a genetic advance as a % of the mean of 217.823 % were recorded for root dry weight per plant. Root dry weight was strongly positively correlated with root fresh weight, root diameter and root length. Seed yield was positively correlated with berry dry weight and traits related to branching, but negatively correlated to root dry weight, suggesting a trade-off between seed and root production. Root fresh weight is the primary contributor to root dry weight. Cluster analysis grouped the genotypes into four clusters, with Cluster 2 showing the maximum potential for improvement in Ashwagandha root yield. The first three principal components explained 85.58 % of the total variation; PC1 primarily explained root-related traits, while PC2 explained branching and reproductive traits. In the chemical quality analysis of eight genotypes in Cluster 2, the germplasm WS 2 (IC - 0604214-X) exhibited the highest withaferin A (0.318 %), alongside moderate biochemical characteristics such as fiber, carbohydrate and protein content. This study provides valuable insights in developing breeding strategies to enhance economically important traits in Ashwagandha but also calls highlights the challenges involved in simultaneously improving both root and seed yield.