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

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.