Abstract:With the strengthening of freshwater eutrophication, the original aquatic vegetation gradually reduced and even disappeared, resulting in the well-functional grass type water degraded to algae-based water. Submerged plant is a key factor for the construction of stable and well-functioning freshwater ecosystems. Therefore, restoration and reconstruction of submerged plants is very important for prevention and control of eutrophication. The growth and development, decline and extinction of submerged plants are closely related with environmental factors due to their aquatic characteristics. In this study, we aim to explore the effects of light intensity, temperature, total nitrogen concentration and their interactions on the growth and development of submerged plants. Our study can shed new light on the mechanism of decline of submerged plants in the eutrophic water, and supply a theoretical basis for species selection in the process of the restoration and reconstruction of eutrophic water. Vallisneria natans is a common submerged plant species in fresh water of the middle-lower reaches of the Yangtze River in China. The effects of light intensities, temperatures and total nitrogen concentrations, 3(light) 3(temperature)×3(nutrient), on the growth of V. natans were investigated with orthogonal design methods in the laboratory. The experimental results showed that (1) light intensity and temperature, as well as their interaction significantly affect the growth of V. natans, V. natans grew well under the conditions of the light intensity in 5320lx, water temperature at 10 ℃, and total nitrogen concentration in 24 mg/L. In addition, V. natans can grow normally when the light intensity were 12000lx and 5320lx, and all of growth parameters were largest when total nitrogen concentration was 4mg/L. However, 2mg/L or 8mg/L total nitrogen concentration as well as 30 ℃, the growth of V. natans was inhibited. (2)The concentration of photosynthetic pigment was highest under the conditions of the light intensity in 5320lx, water temperature at 10 C than other conditions, however, the effect of total nitrogen concentration on the synthesis of photosynthetic pigment of V. natans was little. (3)The physiological activity of V. natans was inhibited under the conditions of the light intensity more than 12000lx or less than 1025lx, or temperature more than 30 ℃, or total nitrogen concentration in 8mg/L. (4) The results of analysis of variance indicated that, in the process of the growth of V. natans, the light intensity and temperature were main factors. Light intensity, temperature, total nitrogen concentration, as well as all the interaction of light intensity and temperature all had significant impact on the synthesis of photosynthetic pigment of V. natans. In addition, light intensity, temperature and the interaction of them were main factors for physiological activity of V. natans. In conclusion, V. natans, as a basal leaves and rosette-type of submerged plant species which can not form canopy, can grow well under the environment of low light intensity and low temperature, however, it can′t endure high nitrogen concentration. Therefore, for the eutrophic water restored for some extent, V. natans can be used as a key species for restoration and reconstruction of aquatic plants in autumn and winter.