Effects Of Turbidity And Low Light Intensity On The Growth Of Macrophytes

The effects of turbidity and low light intensity on the growth and physiological indexes of macrophyts were investigated by laboratory experiments. The influence of water turbidity and low light intensity on photosynthesis of macrophytes were measured with natural and undamaged means by pulse-amplitude modulated fluorometer (PAM). The purpose of this study is to provide scientific basis for the recovery of macrophytes. According to the indexes determined in the study, the conclusions are as follows:1.The ralative growth yield , the photosynthetic rate and the germination of Potamogeton malaianus and Hydrilla verticillata were significantly influenced by the turbidity. The photosynthetic rate of Potamogeton malaianus and Hydrilla verticillata were significantly reduced when the turbidity was more than 120NTU.2.The parameters of chlorophyll fluorescence and the indexes of enzyme show that the low turbidity have not stressed the Potamogeton malaianus and Hydrilla verticillata's growth and photosynthesis. The high turbidity water stressed the two macrophytes and the Fv/Fm, Yield and qP was reduced, enzyme activity was dropt. The suspended solids deposit on the leaves of macrophyts restrained the photosynthesis and accelerated the aging of plants.3.The Hydrilla verticillata's chlorophyll content and chlorophyll a/b was increased on shading. Hydrilla verticillata's parameters of chlorophyll fluorescence and the indexes of enzyme were better than contrast. Hydrilla verticillata's relative growth yield, germination, soluble suger content was reduced because the plant acquire less light.4.The Hydrilla verticillata's germination, chlorophyll content, chlorophyll a/b, soluble suger content, relative growth yield and photosynthetic rate increased since the light intensity was incresed. Some plants died in the 15μmolm-2s-1light intensity and the indexes were lower. The indexes of plants in the 50μmolm-2s-1light intensity were near to contrast. The light intensity of 30~40μmolm-2s-1 is suit for macroyphytes.