Study On The Response Of Physiological And Ecological Of Several Submersed Macrophytes In Aquatic Ecological Restoration

As the main primary producer of aquatic ecosystem, submersedmacrophyte is the base to mentain biodiversity of water-bodies. This kind ofmacrophytes provide food, site and other necessary conditions to build thecomplicated food chain, it also sustain camivorous and detritus food chainindirectly as well, by adding ecological space, restraining biotic and abioticsuspend substance, and improving environmental factors such as the lightintensity and dissolved oxygen. It was reported in this paper those:1. Study on the effect of light on the content of chlorophyll, soluble proteide and MDA; enzyme activity of SOD, CAT and POD of Hydrilla verticillata.2. Investigate on the responses of nitrogen concentration on segregate, height of plant, root length, root number, biomass and tatio of dry weight and fresh weight of three species of freshwater plants, that is Hydrilla verticillata, Vallisneria natans and Potamogeton malaianus with the approaches of exoerimental ecology.The results can be gained as follows:a) The physiological and biochemical attributes of Hydrilla verticillata under different light intensity:1. The content of chlorophyll increased rapidly with the reduce of light intensity, which is 200lux (H5) >500lux (H4) >1250lux (H3). By t-test, there is a highly significant differences between H5 and H3, H5 and H4. (P=0.002,0.003<0.05).2. When the light intensity under 500lux, the soluble proteide content of Hydrilla verticillata decrease, the activity of CAT increased.3. The response of SOD activity at low light was high than that of CAT and POD. When the light intensity under 1250lux(H3), the SOD activity increased, Hydrilla verticillata can maintain metabolism as usual with auto-regulation. While H5(200lux), the activity of SOD reached the peak in the first five days, then droped rapidly.4. The sensitivity of POD was very low with the reducetion of light, the activity of POD increased slightly at 200lux (H5) and 500lux (H4), the differences among experimental groups were not significant.5. The content of MDA of every group changed unconspicuously and the differences among experimental groups were not significant.b) The response of Hydrilla verticillata, Vallisneria natans andPotamogeton malaianus to different concentration of nitrogen1. Hydrilla verticillata:When the concentration of nitrogen was about 8 mg/L, the height of plant and root number were the best.The biomass, segregate,and root length were the best when the concentration of nitrogen was about 16 mg/L. Nurition require of Hydrilla verticillata was different at its different period.Generally to say, the growth of Hydrilla verticillata was the best when the concentration of nitrogen was about 8-16 mg/L .2. Vallisneria natans:The growth of Vallisneria natans was different under differ concentration of nitrogen. The biomass and height of plant were the...