扁蓿豆和苜蓿种子萌发期抗旱性和耐盐性比较

为明晰扁蓿豆[Medicago ruthenica(Linn.)Trautv.]和苜蓿(Medicago varia Martin.)种子萌发期的抗旱性和耐盐性强弱,以不同浓度的聚乙二醇(PEG-6000)和Na Cl溶液模拟干旱和盐胁迫,研究了不同程度干旱和盐浓度对采自甘肃景泰的扁蓿豆和苜蓿品种阿尔冈金(M.varia Martin.cv."Algonquin")种子萌发和幼苗生长的影响。结果表明,干旱胁迫和盐胁迫降低了扁蓿豆和苜蓿种子的发芽率、发芽指数、活力指数,抑制了胚芽和胚根的生长。-0.3~-0.9 MPa和-1.5 MPa的PEG处理下苜蓿和扁蓿豆种子的相对发芽率间无显著差异,-1.2 MPa的PEG胁迫下苜蓿种子的相对发芽率显著高于扁蓿豆。-0.3~-1.2MPa的PEG胁迫下苜蓿种子的相对发芽指数均显著高于扁蓿豆,其相对芽长无显著差异。Na Cl渗透势为-0.9~-1.5 MPa时,苜蓿种子的相对发芽率显著高于扁蓿豆;-0.3~-1.2 MPa的Na Cl胁迫下苜蓿种子的相对发芽指数和相对活力指数均显著高于扁蓿豆。通过种子萌发期的相对发芽率、相对发芽指数、相对活力指数、相对胚根长和相对胚芽长5项指标,应用隶属函数法对参试材料种子萌发期抗旱性和耐盐性进行综合评价的结果表明,苜蓿品种阿尔冈金种子萌发期的抗旱性、耐盐性均强于来自景泰的扁蓿豆。此结果和人们以往对扁蓿豆和苜蓿的认识"扁蓿豆的抗旱性和耐盐性优于苜蓿"不一致。

Comparative study on drought resistance and salt tolerance of Medicago ruthenica and Medicago sativa at seed germination period

To clarify the drought resistance and salt tolerance of Medicago varia and M. ruthenica at seed germination period, the effect of seed germination and seedling growth of the seed of M. ruthenica (collected from Jingtai) and M. varia (Algonquin) were studied by using different concentration of polyethylene glycol (PEG-6000) and NaCl solution to simulating drought and salt stress. The results showed that the both stress of NaCl and PEG decreased the germination percentage, germination index, vigor index of M. ruthenica and M. varia and inhibited the growth of plumule and radical. The differences of relative germination percentage between M. varia and M. ruthenica seeds were not significant under the PEG stress from -0.3 to -0.9 MPa and -1.5 MPa (P>0.05), but the relative germination percentage of M. varia was significantly higher than that of M. ruthenica under -1.2 MPa (P<0.05). The relative germination index of M. varia was significantly higher than that of M. ruthenica under PEG stress from -0.3 to -1.2 MPa, while the relative radical length were not significantly. The relative germination percentage of M. varia were significantly higher than that of M. ruthenica under the NaCl stress from -0.9 to -1.5 MPa, the relative germination index and relative vigor index of M. varia were significantly higher than that of M. ruthenica under the NaCl stress from -0.3 to -1.2 MPa. The comprehensive evaluation of the relative germination percentage, relative germination index, relative vigor index, relative plumule length and relative radical length of M. ruthenica (Jingtai) and M. varia (Algonquin)was done by membership function method which indicated that the drought tolerance and salt tolerance of M. varia seed were stronger than that of M. ruthenica . This result is not consistent with past understanding of "drought resistance and salt resistance of M. ruthenica were stronger than that of M. sativa and M. varia.