大花白麻和罗布麻种子萌发对干旱胁迫的响应

以大花白麻和罗布麻为对象，在不同浓度的PEG溶液（0%、5%、10%、15%、20%、25%、30%、35%）、对应的渗透势（-0.05、-0.15、-0.30、-0.49、-0.73、-1.03、-1.37 MPa）作为干旱胁迫处理，研究干旱胁迫对种子萌发和幼苗生长的影响。结果表明，随着PEG浓度的不断增加，使种子萌发期含水率减少，大花白麻和罗布麻种子的相对发芽率、相对发芽势、发芽指数、活力指数呈明显的下降趋势，推迟了发芽日进程，也抑制了胚芽长、胚根长和幼苗鲜重，各项指标在25%～30%时受抑制程度最明显，罗布麻受抑制程度<大花白麻。在PEG溶液浸种处理的种子复水后仍具有较高的萌发率，发芽高峰期在2～3 d。大花白麻和罗布麻胚芽长、胚根长与对照之间差异显著(P＜0.05），其他浓度与对照之间无显著差异(P＞0.05），罗布麻种子抗旱性>大花白麻，大花白麻和罗布麻最适宜萌发的PEG浓度范围分别为0%~20%、0%~25%。该研究结果可为干旱荒漠区盐碱地人工辅助改良草本植物的选择提供参考，为盐碱地治理提供优良物种。

Response of Seed Germination of Poacynum hendersonii and Apocynum venetum to Drought Stress

In order to understand the influences of drought stress on the seed germination and seedling growth,seeds of Poacynum hendersonii and Apocynum venetum were treated by PEG with the concentrations of 0%,5%,10%,15%,20%,25%,30%,35%,in which the corresponding osmotic potentials were about-0.05,-0.15,-0.30,-0.49,-0.73,-1.03,and-1.37 MPa,respectively.The results showed that the relative germination rate,relative germination potential,germination index and vigor index of the seeds decreased significantly with the increase of PEG concentration,the water content of the seeds decreased during germination,which delayed the daily germination process,inhibited the embryo length,radical length and fresh weight of the seedlings.The most significant inhibition occurred at the PEG concentrations of 25%-30%.The degree of inhibition on A.venrtum was less than P.hendersonii.High germination rates were observed after rehydration with the germination peak of 2-3 days.There were significant differences in embryo length and radicle length between the 5%PEG treatment group and the control(P<0.05),but no significant differences between the other PEG concentrations and the control(P>0.05).The drought resistance of A.venetum was higher than P.hendersonii.The ranges of PEG concentration suitable for the seed germination of P.hendersonii and A.venetum were 0%-20%and 0%-25%.The conclusion can provide a reference for the selection of herbaceous plants and the control of saline alkali land in arid desert area.