Effects of submerged height on allelopathic inhibition of Carex cinerascens to Microcystis aeruginosa in Poyang Lake marshland

In the present study, the allelopathy inhibition of Carex cinerascens soaking culture to Microcystis aeruginosa were studied with batch culture in light incubator controlling light and temperature and outdoors with different submerge height. The results showed that C. cinerascens soaking liquid inhibited the growth of M. aeruginosa and the inhibitory ratios increased with submerge height increasing which increased from 64% to 82%. C. cinerascens mainly secreted allelochemical by root system and dead or damaged tissues. Cell diameter of M. aeruginosa decreased by 10% compared with that of control group which suggested that the cells pyknosis. Intracellular and extracellular polysaccharide content of M. aeruginosa were 1.6~1.8 and 1.7~2.0 pg·cell-1, respectively. These results suggested that M. aeruginosa resist the allelopathic inhibitionby polysaccharide accumulation to form extracellular rubber sheath and single cells assembled to form group. This study provided the basis data forusing ecological regulation water level to control water bloom.