Drought Stress and Recovery Modulate Physiological Traits and Metabolite Profiles in Kaempferia galanga L.

Abstract

Kaempferia galanga L. is a volatile compound-rich herb belonging to the ginger family and has been widely utilized in traditional medicine, pharmacology, and cosmetic applications. The aims of this study were to determine growth, physiological responses, and alterations in hexane extractable compounds, as well as antibacterial activity in plants subjected to water stress and recovery periods. The experiment was conducted using a randomized complete design with two experimental groups and four replications under well-irrigated water and drought conditions. The drought-affected plants, experiencing a 65.34% decrease in soil moisture, demonstrated only a 15.58% fall in leaf relative water content. Drought revealed nonsignificant effects on the plant biomass and pigments of the mature leaves. While physiological adaptation such as the elevation of chlorophyll a+b and carotenoids in the young leaves was observed, that may be related to photosynthesis during the recovery phase. The predominant groups of the phenylpropanoids, such as ethyl p-methoxycinnamate, and the aliphatics exhibited levels of 53.90% and 27.82%, respectively, in the control rhizomes. These contents remained at elevated levels during recovery, confirming that rhizomes had a unique characteristic that differed from leaves. Moreover, the hexane extracts derived from the drought-induced rhizomes showed a minimum inhibitory concentration of Staphylococcus epidermidis at 12,500 µg/mL, which was two times less than the control. The findings demonstrated that the native KG require an adequate water supply, and water deficit management influenced the proportions of plant metabolites. This study may establish a knowledge base for sustainable KG cultivation in future research.