Abstract: We explored the effects of drought and salt stresses on seed germination and seedling growth of Rheum officinale Baill. at different altitudes, growth years and storage periods, with seeds collected from Zhenba County, Shaanxi Province. PEG and NaCl treatments with two osmotic potential levels (-0.3 and -0.5 MPa) were used to simulate drought stress and salt stress, respectively. The number of seed germination was recorded daily and the growth of seedlings was observed. The results showed that the germination rate of seeds collected at the middle altitude of 1650 m was higher than that of seeds collected at the low and high altitudes. Seeds collected at the altitudes of 1650 and 1300 m were more tolerant to drought and salt stresses. With the increases of stress concentration, the inhibitory effect of drought stress on seedling growth was extremely significant. All seedlings died under -0.5 MPa PEG treatment. There was no significant difference in the endogenous GA₃ content of seeds collected at different altitudes, growth years and storage periods. Seed vigor and endogenous GA₃ concentration increased significantly after gibberellin soaking. The germination rate, vigor, and salt tolerance of seeds stored for one year at room temperature were significantly lower than that of newly collected seeds, while the germination rate, vigor, and salt tolerance of seeds from three-year-old plants were higher than those from two-year-old plants. Drought tolerance of seeds from three-year-old plants was stronger. In summary, R. officinale seeds are not suitable for long-term storage at room temperature. Medium altitude and mild salt stress are beneficial to seed germination and seedling growth of R. officinale. Seed quality of three-year-old plants is higher than that of two-year-old plants.

Key words: osmotic stress, altitude, growth year, storage period, seed germination, seedling growth, gibberellin.