Impact of fertilization on drought response in the medicinal herb Bupleurum chinense DC.: Growth and saikosaponin production

Bupleurum chinense DC. is a plant with high medicinal value. Its roots have been used in Chinese medicine for at least 2000 years. Environmental stress has been used as a strategy to optimize yield of important compounds in other crops. The objective of this pot study was to investigate the combined effects of fertilizer and water-stress on total saikosaponin a (SSa) and saikosaponin d (SSd) yield from B. chinense. The 2 × 3 factoral design included two levels of water-stress and three fertilizer amounts. The results showed that mild water-stress significantly increased the SSa and SSd content in B. chinense roots, but decreased root biomass. Total SSa and SSd yield were lower in the water-stressed treatment compared to the well-watered treatment. There was significant interaction between the water and fertilizer treatments and the negative effect of water-stress on total SSa and SSd yield could be partly mitigated through the application of N and P fertilizer. In conclusion, results from this study show that the application of proper amounts of fertilizer are important for medicinal plant production in semi-arid and arid regions, and that it is possible to increase total SSa and SSd yield through the combined use of fertilizer and properly timed exposure to water-stress.