Effects Of Some Environmental Factors On The Photosynthesis Of Myriophyllum Spicatum L. And The Study Of Polyculture Fish With Grass

This paper investigated the effects of light intensity, pH and temperature on the photosynthesis of Myriophyllum spicatum L.. Light compention point were worked out by regression analysis. And photoinhibition was studied outdoors. According to the oxygen consumption of Carassius auratus gibelio and the net oxygen production of M. spicatum L. under the same condition, the biomass ratio of fish and grass was determined preliminarily. To determine the best suitable ratio of fish and grass, the change of situation of the water physic-chemical factors and the growth of fish and grass were studied. Purifying effect of M.spicatum L. on the polluted water in outdoor ponds was discussed. The results were summarized as follows:1. The effects of light intensity, pH and temperature on the photosynthesis of M. spicatum L. Experiment results showed that at a given temperature, net oxygen production of M. spicatumL.was in linear relation to light intensity. Light compention point were worked out by regression analysis. That at various temperatures was 45 lx (5℃), 173 lx (10℃), 308 lx (15℃), 418 lx (20℃) and 495 lx (25℃), respectively. It could be concluded that light compensation points of M. spicatum L. increased with temperature. There was photoinhibition phenomenon on M. spicatum L.. And the light saturation point of M. spicatum L.was 58,1361x in 25℃.The photosynthesis of M. spicatum L.was better in acid water. When pH was 5--10, the net oxygen production of M. spicatum L.decreased with the raising of pH.2. The experiment of polyculture C. auratus gibelio with various biomass of M. spicatum L.(1 preliminary determination of biomass of C. auratus gibelio and M. spicatum L.The polyculture effect of C. auratus gibelio and M. spicatum L.was related to the biomass ratio. According to the oxygen consumption of C. auratus gibelio and the net oxygen production of M. spicatum L. under the same condition, the biomass ratio of fish and grass was determined preliminarily, that was 35~90g. Considering some oxygen consuming factors, such as the fish's excrement and the fodder that hadn't been eaten in the aquarium, in the polyculture experiment of C. auratus gibelio and M. spicatum L., we determined the initial biomass of M. spicatum L.. The control group (just C. auratus gibelio )without M. spicatum L.; experimental group 1(1 a, 1b, 1c) M. spicatum L.: 40g; experimental group 2(2a, 2b, 2c) M. spicatum L.: 80g; experimental group 3(3a, 3b, 3c)M spicatum L.: 120g; experimental group 4(4a, 4b, 4c) M spicatum L.: 160g.(2)The change situation of the water physic-chemical factors and the growth of fish and grass in polyculture system.Clustering analysis of water quality index in various treatments showed that the water quality of experimental group 2 was the best, better followed by the experimental group 3, then worse in group 4, group 1 and control group(without M. spicatum L.)The water was in good quality preliminarily, each group fish's food taking, swimming and so on, They were the same as usual. In the later period, there were dead fish in aquarium. In the end, the degree of fish-dying phenomenon was in turn: experimental group 4 > control group > experimental group 1 > experimental group 3, but no dead fish seen in experimental group 2.The M. spicatum L.growth situations of experimental group 1 and group 2 were similar, while that of group 3 was slightly abdicate to the first two groups. The worst was the experimental group...