Abstract: In general, Elymus nutans grows well in hostile environments at high altitudes. Aluminum (Al) stress is one of the serious factors limiting plant productivity in acidic soils. However, studies of the influence of aluminum on this plant are still lacking. The seeds of wild E. nutans from three different areas in Tibet (Naqu, Shenza and Langkazi Counties) were used as materials in this study. The major experimental method involved hydroponic culture with four concentrations of Al³⁺ (0, 0.5, 1.0 and 1.5 mmol·L^-1) under acidic conditions (pH 4.5). In order to provide robust germplasm resources for the improvement of acid-aluminum soil, the effects of Al³⁺ stress on the seed germination and seedling growth were initially explored. Our investigations indicated that there were no significant differences (P>0.05) in the germination rate of the three samples of wild E. nutans seeds at lower concentrations of Al³⁺ stress (0.5 and 1.0 mmol·L^-1) compared to the control, but that results were adverse at higher concentrations (1.5 mmol·L^-1). The results showed that root length, plant height, root weight and shoots’ weight in the three samples decreased with increasing Al³⁺ concentration. In addition, the MDA and soluble sugar contents of seedlings substantially increased with Al³⁺ application. Data showed that Al was poorly translocated from the roots to aerial parts of the three seedling samples. In the treatment groups, the Al content of roots increased 12.2, 15.3 and 17.5 times more than that of the aerial parts. Al toxicity and phosphorus (P) deficiency often co-exist in acidic soils and limit plant growth and crop production. In this study, we observed that Al stress induced a reduction in P accumulation in the plants. Using eight indicators for seedlings under Al stress, we performed a comprehensive evaluation of Al tolerance of the three E. nutans samples and showed that the Shenza County sample was highly tolerant to aluminum and so could be used for domestication and breeding to provide good germplasm resources for the improvement of acid-aluminum soils.

Key words: Elymus nutans, aluminum stress, seeds germination, seedlings growth, aluminum accumulation, phosphorus content, Tibet