| The status of Chinese eutrophic water is very severe:the ratio of eutrophic water increases every year, and eutrophication degree intensifies continuously. Due to their landscape value, ecological effects, good purifying ability and potentially economic value, hydrophytes have prosperous future in treating eutrophic water.Firstly, this paper summarizes control theory and technology of eutrophication. The traits and feasibilities are discussed and relevant direction is brought forward. Secondly, this paper made a summary of the current situation and progress in the studies on allelopathy. Finally, we select three wetland plants (Canna indica L., Iris tectorum Maxim., Typha latifolia L.) which are implemented widely in the garden landscaping, Chlorella pyrenoidosa and Microcystis aeruginosa. which are the common dominant species to algae blooms as the subjects of study.Specifically, the allelopathic effect of Canna on the growth of Microcystis aeruginosa. and the mechanisms of algal inhibition by Canna leaching liquor were investigated; Further comparisons of anti-algae ability of different parts of Canna, then active component extraction and bioactivity assay were conducted on the plant tissue with the highest bioactivity. Finally, the allelopathic effect among these three different species of wetland plants was compared. On this basis, further research on the allelopathy of the mixed culture water on Chlorella pyrenoidosa were carried out. Thus, it can create a better theoretical basis of both the reasonable construction in garden landscaping of the variety types of wetland plants and establishing environmentally-friendly surroundings.①The culturing water of Canna indica L. had the strong inhibiting effect on Microcystis aeruginosa growing. Moreover, with the increasing of the concentration, the culturing water had better inhibiting effect on Microcystis aeruginosa. Continuous addition assays showed strong growth inhibition by culture solution. The highest inhibitory rate was92.8%in8d experiment. However the effect varied with different sterilizing methods (sig<0.01), its showed that there are some thermally unstable substances in the allelochemicals in the Canna indica L.②The strongest anti-algae effect showed from Canna root and leaf leaching liquor, the inhibition rate to the Microcystis aeruginosa. was93%and96%respectively. The results showed that Canna leaching liquor destroyed the membrane integrity, enhanced the esterase activity, during these processes, normal metabolism was disturbed and then Microcystis aeruginosa was removed.③Accelerated solvent extraction technique increased the extract efficiency, and the extraction yield of leaf can reach14.27%. The methanol-eluted fraction and acetone-eluted fraction form leaf showed the strongest effect, and its I50was2.03mg/m、2.31mg/ml respectively. Anti-algae capacity of methanol-eluted fraction from leaf is better than copper sulphate.④Culturing water of Iris tectorum Maxim. stimulated the growth of C pyrenoidosa. Canna indica L. was positive on growth of the C pyrenoidosa when the concentration of the culturing water was low, and negative when the concentration was high. Typha latifolia L. inhibited the growth of C pyrenoidosa by50.7%. C pyrenoidosa Chlorophyll a(Chl. a) contents differed significantly under three plant species, being significantly high in Iris tectorum Maxim, by1035g/L, and the lowest content of Typha latifolia L. was only41%of the control. Inhibit activities may changed in the co-culture condition.indicating that the allelochemicals secreted by three wetland plants are not the same components, and maybe has a certain cooperate interaction. |
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