Temperature-Mediated Alterations in the Growth, Physiology, Morphology, and Pharmacology of Astragalus membranaceus Bunge: Implications for Medicinal Herb Cultivation and Therapeutic Efficacy

Climate change is known to affect the physiobiochemical aspects of plants throughout their life cycles, including their growth and maturation stages. This study was conducted to assess the influence of different temperatures on the growth characteristics, physiological responses, leaf surface microstructure, and pharmacological properties of Astragalus membranaceus Bunge (Hwang-gi) cultivated in a temperature-gradient greenhouse (T1, control; T2, moderate increase; T3, high increase; and T4, extreme increase). As the temperature was increased, there was a pronounced decrease in the soil moisture content, leading to alterations in the growth patterns of Hwang-gi. Specifically, a reduction in the chlorophyll content was observed, resulting in diminished photosynthetic capacity. Additionally, changes in leaf surface microstructures indicated adaptive strategies aimed at minimizing moisture loss, such as an increase in the trichome density and a reduction in the pore size. Moreover, a pharmacological analysis of Hwang-gi roots showed that the contents of certain secondary metabolites, in this case astragaloside I, calycosin-7-O-glucoside, and formononetin, were significantly altered by temperature stress. These findings suggest that climate change poses a potential threat to the growth, physiological function, and pharmacological quality of Hwang-gi, highlighting the need for adaptive strategies to protect this valuable medicinal herb.