Evaluation of different ecological regions for cultivation of best quality Bupleurum: a case study from Shanxi, China

Bupleurum, a plant of the genus Bupleurum L. in the family Umbelliferae, is prevalent and extensively applied in traditional medicine systems across East and Southeast Asian countries for the treatment of colds, malaria, hepatitis and other diseases. In the current Chinese herbal medicine market, only the dried roots of two species, Bupleurum chinense DC. and Bupleurum scorzonerifolium Willd., are authentic herbs, and their cultivars dominate as the commercial source, contributing to about 80% of the market share. Shanxi Province, known as the suitable habitat for Bupleurum in China, has a diverse ecosystem and geographical areas with diverse environmental conditions. These diversity ecosystem and environmental conditions cause prominent variations in the content of active ingredients of Bupleurum L. across different sites. Therefore, analyze the ecological, geographical, and soil factors that influence the quality of Bupleurum and to recommend the best suitable sites for cultivation of Bupleurum. This study demonstrates a close correlation between the quality of Shanxi Bupleurum sp. and different ecological factors. A total of 70 sets of Bupleurum and soil samples were collected from 25 counties across 6 cities in Shanxi Province. Consequently, the saponin contents of Datong, Shuozhou and Yizhou were generally higher than those of Linfen, Jincheng and Yuncheng. Bupleurum from northern Shanxi exhibits higher saikosaponin content compared to that from southern Shanxi; The total content of the five saponins shows a significant positive correlation with longitude (*P < 0.05) and a highly significant positive correlation with latitude and altitude (**P < 0.01). Saikosaponin levels positively correlate with latitude, longitude, and altitude; Meanwhile, the significance ranking of these ecological factors is: monthly average temperature is equal to monthly average surface temperature is greater than monthly sunshine hours. Low temperatures, arid conditions, and longer sunlight exposure are optimal conditions for the accumulation of saponin components; Besides, high-saponin Bupleurum is typically cultivated in low alkaline soils with low nitrogen, while the habitat of Shanxi Bupleurum is differentiated into four regions. Overall, the current study presents a foundation for selecting the best cultivation sites for Bupleurum and provides a valuable reference for evaluating other medicinal herb production regions.