以新疆橡胶草为材料，采用聚乙二醇（PEG －6000）模拟干旱法，PEG溶液渗透势范围为－1．0～0．0 MPa ，探讨干旱胁迫对橡胶草种子发芽势、发芽率、日相对发芽率、平均发芽速率、发芽指数、活力指数、幼根长度、幼叶长度以及幼叶宽度的影响。结果表明，随着PEG溶液浓度的增加，种子活力以及幼苗长势均呈现出先升高而后降低的趋势。当PEG溶液渗透势为－0．4 MPa时，发芽指数和活力指数显著低于对照组，而其幼根长度、幼叶长度以及幼叶宽度与对照组差异不显著，说明橡胶草种子活力比幼苗生长对于干旱胁迫更敏感；当PEG溶液渗透势为－0．8 MPa时，橡胶草种子萌发受到完全抑制，表明－0．8 MPa为橡胶草种子萌发的临界水势。%Seeds of Taraxacum kok-saghyz Rodin (TKS) were employed as the experimental material in this paper , and the effects of simulated drought stress with different concentrations and osmotic potentials (-1 .0~0 .0 MPa ) by polyethylene glycol (PEG-6000 ) were investigated on seed germination potential ,seed germination rate ,seed daily ger-mination rate ,average seed germination rate ,germination index ,viability index ,radicle length ,germ length and germ width .The results showed that the variation trend of seed activity and seedling growth of TKS was firstly ascending and then gradually dropping with the levels and time of simulated drought stress by PEG increased .When osmotic potential of PEG reached -0 .4 MPa ,TKS seeds germination was promoted ,and their germination index and viability index were significantly higher than the CK group .However ,the differences in radicle length ,germ length and germ width tested in this research were not significant from the CK group ,indicating that the seed activity might be more sensitive to PEG-simulated drought stress than seedling growth .The seeds treated with -0 .8 MPa osmotic potential by PEG could not ger-minate at all ,suggesting that -0 .8 MPa osmotic potential was critical for the seed germination of TKS .
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