[Objective] This study aimed to investigate the effect of soaked seed with rare earth on the seed germination and seedling growth of tartary buckwheat under different water conditions. [Method] A hydroponic experiment was carried out with the seeds of tartary buckwheat variety ＂Heifeng No.1＂ in the year 2012. [Result] ①In the normal irrigation, suitable concentration of rare earth increased the germination rate, vital index, germination index and sprouting index of tartary buckwheat seed; at the same time, the leaf area, stem thickness, total root length, root weight,leaf relative water content, proline content, soluble sugar content, soluble protein content, root activity, SOD activity and POD activity of seedling were significantly enhanced, while the relative conductivity and MDA content of tartary buckwheat were decreased obviously. ② Compared with water stress and normal irrigation, the indices of germination potential, germination rate, vital index, germination index, the leaf area, stem thickness, total root length, root weight, leaf relative water content,proline content, chlorophyll content, soluble sugar content, root activity, SOD and POD activity were reduced, while relative conductivity and MDA content were increased, and the extents differed in the treatment of different chemical regulators,and the varied range increased with the higher severity of soil water stress. ③ Under water stress, soaking seeds with suitable concentration（200 mg/L） of rare earth could significantly improve the SOD and POD activity, leaf area, total root length,chlorophyll content and root activity compared with CK. They could increase leaf relative water content by 8.9% and 10.8%, proline content by 7.5% and 8.2%, TTC activity by 13.8% and 16.7%, and soluble sugar content by 10.4% and 7.9% under mild and severe water stress, separately. [Conclusion] The appropriate concentration of rare earth was 200 mg/L.
