OBJECTIVE: To uncover the inhibition of Allium cepa (onion) on Microcystis aeruginosa, and identify the allelochemicals in onion.METHODS: The inhibition of different concentrations of onion bulb and onion leaf water extracts on M. aeruginosa were investigated, and the allelochemicals of onion bulb were extracted and identified by organic solvent and GC-MS, repectively.RESULTS: Both onion bulb and onion leaf water extracts had, to different degree, inhibitory effect on the growth of M. aeruginosa. Compared with the control group, the onion bulb and onion leaf extracts treatment groups were lower than the control group in the same period, and the inhibitory effect were more obvious with the increase of the water extract concentrations. The inhibition ratios of water extracts from onion bulb to M. aeruginosat were 100% on the fifth day, except 5 ml/L water extract treatment group. And the inhibition ratio of 40 ml/L water extract treatment group from onion leaf to M. aeruginosat was 97. 4% on the sixth day. The main allelochemicals in onion includes tris (hydroxymethyl) nitromethane, nonanoic acid, capric acid and methane sulfonic anhydride.CONCLUSION: The inhibition of onion bulb water extracts on Microcystis aeruginosa are very strong and better than onion leaf water extracts.
Gas Chromatography-Mass Spectrometry Microcystis