Correlation, Path Coefficient and Genetic Diversity Analysis in EMS Induced Cultivars of Ashwagandha [Withania somnifera (L.) Dunal].

Abstract

Withania somnifera (L.) Dunal, commonly known as ashwagandha, belongs to the family Solanaceae is a significant medicinal plant in Ayurveda, valued for its high-quality roots and usage to treat an extensive physiological disorder. To enhance sustainable production and genetic gains, mutagenic treatment was applied to generate genetic variation. This study focused on investigating probit, genetic parameters, correlation associations, and path analysis in an M₁ population of two cultivars, NMITLI-118 (NM-118) and CIM-Pushti (CIM-P), exposed to Ethyl Methane Sulphonate (EMS). A total of fifteen morphological traits and seven biochemical markers were assessed across five different EMS doses: 02%, 0.4%, 0.6%, 0.8%, and 1%, with a control. The experiment was conducted at Mahatma Gandhi Central University, Motihari, Bihar. Significant genetic improvement along with high heritability were observed for traits like no. of leaves, seeds per plant, and berries per plant in NM-118 while, in CIM-P no. of leaves, seeds per plant, and main root length exhibited high genetic gain. Strong positive correlations were found between root dry wt. and root fresh wt. (0.852✷✷/0.894✷✷), no. of branches (0.721✷✷/0.816✷✷), and plant height (0.743✷✷/0.809✷✷) in NM-118, while CIM-P showed strong correlations with root width (0.864✷✷/1.076✷✷), root fresh wt. (0.983✷✷/0.998✷✷), and main root length (0.979✷✷/0.987✷✷). Path coefficient analysis revealed that the no. of seeds per berry, 1000-seed wt., and total seeds per plant had a strong positive direct effect on root dry wt. in NM-118, while in CIM-P, total seeds per plant, main root length, and root fresh wt. had the highest direct effects. In conclusion, the root dry yield of NM-118 is higher with a 1% EMS dose compared to all other treatments and cultivar. Additionally, the study found that CIM-P, treated with a 0.8% EMS dose, has the highest concentration of steroidal lactones/withanolides among the selected cultivars and doses, making it the most effective source for extracting withanolide A from the Withania mutant population. These traits are promising for breeding programs targeting improved root dry production in Withania cultivars.