Comparison on Salt Tolerance of Nine Submerged Macrophytes

Salt tolerance of nine submerged macrophytes in coastal wetland of Tianjin was compared through measuring relative growth rate of the submerged macrophytes by river sediment culture and hydroponic culture. The results showed that only Ruppia maritima and Potamogeton pectinatus could survive when grown in river sediments. The nine macrophytes were different in salt tolerance under hydroponic conditions with various salinity of the reclaimed wastewater. Potamogeton crispus and Potamogeton pusillus tolerated salinity as high as 5.3 g·L-1, while Ceratophyllum demersum and Myriophyllum spicatum tolerated salinity 7.6 g·L-1 and 10.1 g·L-1. The salt tolerance of R. maritima and P. pectinatus were highest, being above 10.1 g·L-1. Based on the salt tolerance, the nine plants followed the order: R. maritimP. pectinatusM. spicatumC. demersumP. crispusP. pusillusPotamogeton malainusHydrilla verticillataVallisneria asiatica. The results indicated that R. maritima and P. pectinatus could be used as the pioneer plants to reconstruct submerged vegetation in the water body containing high salinity in coastal wetlands.