Abstract:

[Objective] This study was conducted to clarify the adaptability of seed germination and seedling growth of Astragalus laxmannii to different salt stresses. [Method] Astragalus laxmannii seeds were exposed to five gradient concentrations of NaCl, Na₂SO₄, and Na₂CO₃ solutions respectively at 0 （CK）, 10, 20, 30, and 40 mmol/L. Three replicates were set for each treatment concentration of each salt solution. Under the treatments of different salt solutions, the germination rate, germination potential, germination index, vigour index, and relative salt damage rate of Astragalus laxmannii seeds were calculated, and the seedlings′ height and root length were measured. [Result] The indexes associated with seed germination and seedling growth of Astragalus laxmannii declined as salt solution concentrations increased. Compared with CK group, the germination rate, germination potential, germination index, and vigour index of Astragalus laxmannii seeds decreased significantly （P<0.05） when the concentration of NaCl, Na₂SO₄, and Na₂CO₃ solutions was 40 mmol/L, and the seedlings′ height and root length decreased significantly （P<0.05） as well. The Astragalus laxmannii seedlings′ root length in 10 mmol/L Na₂SO₄ solution treatment group was 5.5% longer than that in CK group, indicating the promoting effect of Na₂SO₄ solution on the seedlings′ root growth at low concentrations. Na₂CO₃ solution treatments resulted in severe salt damage to Astragalus laxmannii seeds. The indexes associated with seed germination and seedling growth of Astragalus laxmannii in Na₂CO₃ solution treatment groups were all significantly （P<0.05） lower than those in CK group, and the differences among varied treatment concentrations were large. [Conclusion] Astragalus laxmannii seeds were most tolerant to Na₂SO₄ salt stress, followed by NaCl and Na₂CO₃ salt stresses. While low concentrations of Na₂SO₄ solution had certain promoting effect on seed germination and seedling growth of Astragalus laxmannii, Na₂CO₃ solution had strong inhibitory effect.

Key words: Astragalus laxmannii, germination rate, germination index, vigour index, seed