The samples were prepared by following the method provided by China Pharmacopeia [15] . The chromatographic condition followed the guidelines set by the Standard Administration of the People's Republic of China [16] . A Waters (Milford, MA, USA) chromatography system equipped with 1525 Binary HPLC pump, 2487 dual λ absorbance detector, and 2707 autosampler was used to perform the HPLC analysis and to determine the content of four active saponins. The column configuration consisted of a Waters SYMMETRY C18 reserved-phase column (5 μm, 250 mm × 4.6 mm) and a SYMMETRY C18 guard column (5 μm, 200 mm × 4 mm). The column temperature was maintained at 30°C. UV absorption was measured at 203 nm.
Methyl alcohol (MeOH) and acetonitrile (MeCN) (HPLC grade) were purchased from Tedia Co., Inc. (Fairfield, OH, USA). Ultrapure water was generated with an ultrapure water system (Shanghai Ultrapure Technology, Shanghai, China). Standard ginsenosides Rg1 (110703-201027), Rb1 (110704-201122), Rd (111818-201001), and notoginsenoside R1 (110745-200617) were purchased from the National Institute for the Control of Biological and Pharmaceutical Products (Beijing, China). The contents of these four active saponins were determined from those dried roots that were harvested from the pots with different water stresses.
Methyl alcohol (MeOH) and acetonitrile (MeCN) (HPLC grade) were purchased from Tedia Co., Inc. (Fairfield, OH, USA). Ultrapure water was generated with an ultrapure water system (Shanghai Ultrapure Technology, Shanghai, China). Standard ginsenosides Rg1 (110703-201027), Rb1 (110704-201122), Rd (111818-201001), and notoginsenoside R1 (110745-200617) were purchased from the National Institute for the Control of Biological and Pharmaceutical Products (Beijing, China). The contents of these four active saponins were determined from those dried roots that were harvested from the pots with different water stresses.