Effects of Salinity and Water Depth on Germination of Phragmites australis in Coastal Wetland of the Yellow River Delta

Phragmites australis, a perennial herb and a widespread species, is widely distributed in coastal wetland in the Yellow River Delta. Laboratory experiments were carried out to assess the effects of water and salinity on seed germination of P. australis and recovery response after seed transferred to distilled water. The germination responses of seeds were determined over a wide range of salinities of 0, 0.5, 1, 2, 2.5, and 3% and water depths of 0, 2, 4, 6, 8, 10, and 15?cm. Final percent germination and germination speed except for at 0.5% salinity treatment were decreased with increasing salinities. Lower salinity (0.5%) could stimulate germination of P. australis, while seed germination was nearly inhibited completely at salinity 3%. P. australis percent germination was decreased with water depth increasing except 2?cm water depth treatment. Percent germination and speed were great and fast at lower water depth. After end of the recovery period, the final percent germination of P. australis after high salinity treatments (2, 2.5, and 3%) was up to 80%, while those after low salinity treatments were lower than 1%, and percent germination after different water depth treatments was zero. The results indicate that it is possible to accelerate the degraded coastal wetland restoration process of P. australis population by sexual ways in the Yellow River Delta.