Seed germination environments of Typha latifolia and Phragmites australis in wetland restoration

Seeds are materials of redevelopment of plant communities, and can be valuable in the wetland conservation and restoration if the seeds germinate and survive. Sexual reproduction of those species is considered the simple and low-cost way to restore wetland. However, seeds usually have the characteristics of deep dormancy and low germination rate, so how to break these bottle-necks is critical to reestablish plant populations. We investigated seed germination environments of Typha latifolia and Phragmites australis, which were the dominant species of the riparian wetland along the downstream of Songhua River, Northeast China, and used to occupy riparian areas. This study involved pretreatment and controlled experiments. Treatments of soaking seed (untreated, distilled water soaked, H2O2 soaked, H2O2 soaked and then distilled water cleaned, KNO3 soaked, KNO3 soaked and then distilled water cleaned, KMnO4 soaked and KMnO4 soaked and then distilled water cleaned) and trails on the effect of water depth (0, 2, 4, 6, 8, 10 and 15 cm) on germination were conducted to explore the most effective pretreatment method and optimum water depth of seed germination of T. latifolia and P. australis. Results showed seed-soaking and water depth both had significant influence on seed germination of T. latifolia and P. australis. Based on the result, we found that success in establishing T. latifolia and P. australis in wetland restoration project can be greatly enhanced by treating seeds before sowing. T. latifolia seeds are more adaptive to aquatic condition, and P. australis seeds are more favorable of wet or moist conditions. A main strategy provided from our experiment to accelerate wetland plants restoration is as followed: T. latifolia and P. australis seeds would be soaked in an aqueous solution of 0.1% KMnO4 and a solution of 0.1% KNO3 for 8 h, and then rinsed with distilled water before sowing. T. latifolia seeds are sowed at aquatic condition (about 8 cm) and P. australis seeds are sowed at shallow water (<2 cm). The strategy provide future insight into how to use seed germination successfully in wetland plant restoration.