青海野决明、芒颖大麦草和盐生草种子萌发对盐分和干旱胁迫的响应特征

Seed germination response characteristics of Thermopsis przewalskii,Hordeum jubatum,and Halogeton glomeratus under salt and drought stresses

以采集于甘肃省境内的青海野决明(Thermopsis przewalskii)、芒颖大麦草(Halogeton glomeratus)和盐生草(Hordeum jubatum)种子为材料,调查了模拟盐分(NaCl溶液)和干旱(聚乙二醇溶液)胁迫条件下种子萌发情况。结果显示,3种种子的最终萌发率(FGP)均随盐分和干旱胁迫的加剧呈下降趋势,初始萌发时间呈延迟趋势,平均萌发时间呈延长趋势。盐分胁迫条件下,青海野决明、芒颖大麦草和盐生草种子的FGP均以对照和轻度胁迫条件(-0.6～-0.3MPa)下为高,最高FGP依次为97%、86%和76%,萌发耐盐极限值分别出现在-2.1、-2.1和-3.3 MPa左右,耐盐指数分别为0.76、0.70和0.84。干旱胁迫条件下,青海野决明、芒颖大麦草和盐生草种子FGP分别在-0.3～0MPa、0MPa和-2.1～0MPa渗透势条件下为最高,分别为97%、76%和68%,萌发耐旱极限值分别出现在-2.4、-2.4和-3.5MPa左右,耐旱指数分别为0.71、0.72和0.88。

The seeds used in this study were collected from Thermopsis przewalskii,Hordeum jubatum,and Halogeton glomeratus growing in the desert region of Gansu Province.Seed germination characteristics under salinity and drought stress[imposed by increasing concentrations of sodium chloride(NaCl)and polyethylene glycol(PEG),respectively]were investigated.The results showed that,with the osmotic potentials of solutions of NaCl and PEG decreasing,the final germination percentages(FGP)of the tested seeds of the three species decreased,initial dates of germination were delayed,and mean germination time was prolonged.T.przewalskii,H.jubatum,and H.glomeratus showed the highest FGP values(97%,86%,and76%)when treated with0,-0.3,-0.6MPa solutions of NaCl(salinity stress;P<0.05,N=4),respectively.The critical osmotic potentials of NaCl solution under which seeds could germinate were-2.1,-2.1,and-3.3MPa,respectively.The values of salinity tolerance indices were0.76,0.70,and0.84,respectively.T.przewalskii,H.jubatum,and H.glomeratus showed the highest FGP values(97%,76%,and68%)when treated with-0.3~0MPa,0MPa,and-2.1~0MPa solutions of PEG(drought stress),respectively.The critical osmotic potentials of PEG solution under which seeds could germinate were-2.4,-2.4,and-3.5MPa,respectively.The values of drought tolerance indices were0.71,0.72,and0.88,respectively.