Effects of Eichhornia crassipes allelochemicals on the growth of two mono- and co-cultured algae Microcystis aeruginosa and Scenedesmus obliquus
凤眼莲化感物质对铜绿微囊藻、斜生栅藻生长及细胞数相对比例的影响

To explore the possibility of using allelochemicals in solving the problem of algal blooms in eutrophicated shallow lakes, five allelochemicals found from roots of Eichhornia crassipes (linoleic acid, 1-linoleoyl-rac-glycerol, propionamide, N-phenyl-2-naphthylamine and nonanoic acid) were tested with mono- and co-cultured algae Microcystis aeruginosa and Scenedesmus obliquus. The results showed that components and doses of the allelochemicals, as well as culture modes, affected the growth of the two algae significantly (p<0.001). The allelochemicals generally promoted the growth of the algae when added at low concentrations (0.1~1.0 mg·L-1) and during early culture stages, while such effects turned into inhibition when allelochemical concentration was increased (10.0 mg·L-1) and the culture stage was extended. Among the fived allelochemicals tested, nonanoic acid had the strongest effect on both algae, whereas individually, M. aeruginosa was most affected by propionamide, and S. obliquus by linoleic acid. Cell number proportions of S. obliquus in co-cultures were also increased by nonanoic acid at a concentration of 0.1~1.0 mg·L-1 and the other allelochemicals at 10.0 mg·L-1 (p<0.05). This research indicated a promising potential of the application of Eichhornia crassipes allelochemicals in control of aquatic algae.