水分胁迫对发草种子萌发和幼苗生长的影响

Effects of water stress on seed germination and seedling growth of Deschampsia caespitosa collected from five provenances

水分是影响发草种子萌发和幼苗成功定植的主要限制因素,也是决定高寒退化湿地生态修复能否成功的关键所在。基于此,本研究以青海省和四川省5个地理种群发草(Deschampsia caespitosa)为研究对象,采用不同PEG浓度溶液模拟水分胁迫环境,测定不同采集地发草发芽率、发芽指数、幼苗高度及胚根长度。结果表明:随水分胁迫程度增加,发草种子发芽率、发芽指数、幼苗高度和胚根长度不断降低。水涝(年均降水量860 mm)或干旱(年均降水量150 mm)条件抑制发草种子的萌发和幼苗生长,而湿生条件(年均降水量400~800 mm)是发草种子萌发和幼苗建植的理想环境。水势模型能准确预测发草种子在不同水势条件下种子萌发进程,预测结果与实测种子发芽率一致。由此可见,水分条件对发草种子萌发和幼苗生长具有可塑性,可为发草在高寒退化湿地生态修复和人工引种驯化提供基础数据。

Water is regarded as one of the crucial abiotic factors that determines the fate of Deschampsia caespitosa seed germination. Consequently, success in terms of seed germination will determine the effect of ecological restoration in alpine wetlands. Therefore, we collected seeds from fruits of D. caespitosa from five provenances in Qinghai and Sichuan Province,and conducted a seed germination experiment to examine the effect of water potential on its seed germination ability and seedling growth. Our results demonstrated that seed germination rate, seed germination energy, seedling height, and radicle length decreased with increasing concentration of Polyethylene glycol 6000. Seed germination and seedling growth of D.caespitosa seeds collected from waterlogged(mean annual rainfall 860 mm) or arid(mean annual rainfall 150 mm) areas were largely inhibited. Contrasting this, germination and seedling growth of seeds collected from wetlands(mean annual rainfall 400~800 mm) were improved. Our study clearly showed that the hydrotime model can adequately describe the germination time course of D. caespitosa seeds under different water potentials, and the conclusion derived from the hydrotime model is consistent with the observed data. In conclusion, the water conditions of D. caespitosa had a variable role in regulating the seed germination and seedling growth. These findings could shed a light on the restoration of degraded wetlands and cultivation and breeding of D. caespitosa in alpine wetland region.