紫花苜蓿种子萌发及幼苗生理特性对PEG6000模拟渗透势的响应

用不同质量浓度PEG6000(0%、5%、10%、15%、20%、25%、30%,渗透势分别为0、-0.06、-0.17、-0.32、-0.53、-0.79、-1.10 MPa)控制渗透势,研究紫花苜蓿种子萌发及幼苗生理特性对不同渗透势的响应.结果表明: 种子5项萌发指标均随渗透势降低呈先升后降趋势,-0.06 MPa时萌发指数和活力指数最高,-0.17 MPa时发芽率、发芽势和发芽指数最高;幼苗过氧化物酶、超氧化物歧化酶、过氧化氢酶活性和叶绿素含量均随渗透势降低呈先升后降趋势,-0.17 MPa时各指标值最高;叶绿素a/b随渗透势降低呈先降后升趋势,-0.06 MPa时最低;游离脯氨酸、丙二醛含量和相对电导率随渗透势降低而持续升高.渗透势为-0.06～-0.17 MPa时,种子萌发和幼苗生理综合评价结果最优,是最适宜种子萌发的渗透势条件,而当渗透势低于-0.79 MPa时,对种子萌发产生抑制.

Response of seed germination and seedling physiological characteristics of Medicago sativa to the simulated osmotic potential of PEG6000.

The responses of seed germination and seedling physiological characteristics of alfalfa to different osmotic potentials were studied with the varied concentrations of PEG6000 (0%, 5%, 10%, 15%, 20%, 25% and 30% corresponding to osmotic potential of 0, -0.06, -0.17, -0.32, -0.53, -0.79 and -1.10 MPa, respectively) in this study. Five indexes of seed germination increased firstly and then decreased with a decrease of osmotic potential. Indexes of germination and vigor were the highest when osmotic potential was -0.06 MPa. Rate, potential and index germination reached the maximum when osmotic potential was -0.17 MPa. Seedling POD, SOD, CAT activities and chlorophyll content increased firstly and then decreased with a decrease of osmotic potential, and indexes reached the maximum when osmotic potential was -0.17 MPa. The ratio of chlorophyll a to chlorophyll b decreased firstly and then increased with a decrease of osmotic potential, and it reached the minimum when osmotic potential was -0.06 MPa. Pro, MDA and REC increased with a decrease of osmotic potential. Seed germination and the comprehensive indexes of seedling physiology were optimal for seed germination when osmotic potential was -0.06--0.17 MPa. Seed germination was restrained when the osmotic potential was lower than -0.79 MPa.