Physiological mechanism of Eichhornia crassipes in inhibiting the growth of Microcytis aeruginosa.
Water hyacinth (Eichhornia crassipes (Mart.) Solms), an invasive plant, is used to control algae-polluted water, but the mechanism among which is not clear. In this study, the allelopathic effects of water hyacinth on the growth of Microcytis aeruginosa were investigated. The physiological changes of M. aeruginosa such as chlorophyll content, superoxide dismutases (SODs), peroxidases (PODs), total protein contents (TPCs), and MDA contents were also determined. Our results showed that higher density of water hyacinth extracts and ethyl acetate fractions all showed significant allelopathic inhibition on the growth of M. aeruginosa. The ethyl acetate fraction considerably reduced the algae chlorophyll content. The higher concentration used of ethyl acetate fraction, the lower the chlorophyll content of algae. The activity of SODs and PODs were quite reduced after 10-day treatment by ethyl acetate fraction. The TPCs and MDA contents were also found to be decreased after 4-day treatment. It is inferred that water hyacinth inhibited the algal growth by released allelochemicals and affected diversity of biochemical and physiological attributes, and also lead to the membrane injury in the M. aeruginosa cells.