Abstract: Na₂SO₄, NaCl and Polyethylene glyecl (PEG 6, 000 mol.wt.) were used in a series of labbased experiments to comparatively investigate their effect on germination of Puccinellia tenuiflora and its mechanism.The results showed that total germination percentage linearly declined with decreasing osmotic potential (OP) in solutions of NaCl, Na₂SO₄ and PEG.On isopotential basis, the percent of germination in tested solutions was Na,SO4>NaCl>PEG.NaCl and Na₂SO₄ influence germination chiefly due to changing water uptake and producing toxicity to membrane, and would thus disturb membrane rnetabolism.Their mechanism, based on the results of correlation and path analysis, is summarised as follows: (1)direct positive effect of water absorption of seeds dependent on OP level and Na concentrations caused by NaCl and Na₂SO₄ solutions on germination (with path coefficient of 0.73); (2)direct negative effects of toxicity to membrane of seeds produced by Na concentrations of solutions (-0.51); and (3)indirect positive and negative effect (0.30 and -0.24) of the entry of Na into seeds on germination through causing increase of water uptake and aggreviation of toxcity to membrane of seeds, respectively.

Key words: Puccinellia tenuiflora, Germination, Osmotic potential, Water uptake, Membrane leakage

摘要： 耐碱茅种子在盐(NaCl与Na₂SO₄)及干旱(PEG-6000模拟)胁迫下发芽及其机制的比较研究表明,种子发芽率随溶液渗透势的降低而下降,在等渗条件下三种溶液中的发芽率次序为Na₂SO₄>NaCl>PEG。NaCl与Na₂SO₄主要通过影响种子吸水量及对膜的毒性影响发芽,根据相关及通径分析结果,其机制为:(1)溶液渗透势及Na⁺浓度决定的种子吸水对发芽的直接正效应(通径系数0.73);(2)溶液Na⁺浓度引起的膜毒性对发芽的直接负效应(-0.51);(3)种子从溶液中吸收Na使种子吸水增加对发芽的间接正效应(0.30)及使膜毒性增大对发芽的间接负效应(-0.24)。

关键词: 碱茅, 发芽, 渗透势, 水分吸收, 膜透性