Effects of overlying water and sediment from Donghu Lake of Wuhan on the growth of Potamogeton maackianus A. Benn

The effects of the overlying water and sediment from the heavily polluted area of Donghu Lake of Wuhan on the growth of Potamogeton maackianus A. Benn. were surveyed under using artificial culture method. The shoots of P. maackianus are well developed on the lake sediment when it is cultured in cement tank, and the biomass and shoot height of the plant are both much higher than those of the control plants cultured on the brown clay in the same tank. The activity of root system in the lake sediment is also much higher than that of the root system in clay. However, the roots of this plant are slender and the root number per shoot is lower in the lake sediment as compared to the control. It is shown that the sediment is certainly the main source of nutrients for submerged macrophytes and the roots play an important role in the uptake of nutrients from sediment besides the attachment to substrate. The results also showed that the overlying water from the heavily polluted area of Donghu Lake affected on the growth and development of P. maackianus. When P. maackianus grow in the lake water, their biomass, weight ratio between root weight and shoot weight and root numbers are low. The mechanism responsible for the extinction of P. maackianus and strategies for aquatic macrophyte rehabilitation are also discussed