Physiological and Morphological Variation in Withania somnifera under Contrasting Agro-Climatic Conditions

Withania somnifera (Ashwagandha) is a medicinal plant from the Solanaceae family that is highly regarded for its root-derived withanolides. In order to identify the primary traits that influence productivity, this investigation evaluated physiological and morphological variation in two starkly different agro-climatic environments: Chennai (Tamil Nadu) and Jabalpur (Madhya Pradesh). Uniform agronomic practices were implemented during field trials in rainfed kharif conditions. The average plant height was 80.30 cm in Chennai and 88.53 cm in Jabalpur, while the root yield was 8.58 g and 10.57 g per plant, respectively. Regression analysis revealed that plant height and root area significantly influenced root yield in Chennai (p < 0.05), whereas leaf length was the only trait showing a significant association with root yield in Jabalpur (p < 0.05). Differences in shoot–root ratio between locations were also statistically significant, indicating environment-specific biomass allocation patterns. In Chennai, root area and plant height were identified as significant predictors of root yield, while leaf length was the sole significant factor in Jabalpur .Theincreased allocation of biomass to roots was indicated by lower shoot–root ratios. The results emphasize the genetic and phenotypic diversity of Withania somnifera and identify traits—particularly shoot–root ratio, root area, and leaf length-as potential selection criteria for breeding initiatives that are designed to enhance yield and stress tolerance.This study contributes to plant science by demonstrating how agro-climatic variability alters trait–yield relationships in a medicinal crop of high economic importance. It advances understanding of phenotypic plasticity and biomass allocation strategies in Withania somnifera, and establishes measurable traits-such as shoot–root ratio, root area, and leaf length-as reliable indicators of adaptive performance and yield potential.