Effect of different salinity on physiological features of Vallisneria natans The uptake of nitrate and ammonium by the root of Vallisneria natans Effects on the transformation of phosphorus in sediment with growing of Vallisneria natans Competition between Myriophyllum spicatum L. and Vallisneria natans (Lour.) Hara at Different Growth Stages REPRODUCTIVE ECOLOGY OF VALLISNERIA NATANS Effects of cyanobacterial accumulation and snail grazing on the growth of vallisneria natans Effects of environmental factors and their interaction on Vallisneria natans by orthogonal test The Influences of Suspended Sands on Photosynthetic Fluorescence Characteristics of Vallisneria natans in Turbidity Waters