Temperature stress and its effects on phytochemical dynamics and antioxidant activity in Withania somnifera (L)....

Elevated temperature stress limits the growth, metabolism and productivity of medicinal plants. However, the response of Withania somnifera (L.) Dunal (Ashwagandha) which has diverse therapeutic properties, to elevated temperature stress remains unexplored. This study investigated the effects of elevated temperature stress exposure on the phytochemical content and antioxidant activity of Ashwagandha four varieties namely: Vallabh 01, Vallabh 02, Pratap, and Chetak, across leaf, stem, root, and fruit parts. The selected varieties were exposed to ambient temperature (10.4 ± 2.6 to 31.6 ± 5.9 ℃) and elevated temperature (ET) levels (13.5 ± 3.5 to 34.3 ± 5.6 ℃) in net house and control environment facility chamber, respectively from November 2021 to April 2022. Fruiting stage samples of different parts of all varieties from both treatments were analysed for total phytochemical content, total flavonoid content (TFC) and antioxidant activity. The results revealed the variable response of varieties and their parts to ET stress. ET stress enhanced the cumulative (root + stem + leaf + fruit) phytochemical content of Vallabh 02, Pratap and Chetak by 112.9%, 15.2%, and 84.9%, respectively, and suppressed in the Vallabh 01 (3.6%). TFC and antioxidant activity were significantly (p < 0.05) higher under ET stress in all the varieties in the following order Pratap > Chetak > Vallabh 01 > Vallabh 02. The findings indicate that ET stress exposure significantly alters as well as enhances Ashwagandha varieties' total phytochemical content and antioxidant activity. Among the four varieties, Pratap is the most tolerant to ET stress. This study indicates that climate change associated ET levels up to 2 ℃ may enhance therapeutic potential of Ashwagandha varieties through synthesis of novel and unique phytochemicals. Novel knowledge of ET levels exposure to favour the production of specific phytochemicals can aid in optimizing the cultivation of medicinal plants for higher yields of desired medicinal compounds.

The online version contains supplementary material available at 10.1007/s12298-025-01594-2.