Allelopathic effects of three ornamental submerged macrophytes on five eutrophic algae

Some submerged macrophytes may inhibit the growth of Eutrophic algae by excreting allelopathic substance. Allelopathic inhibition of three submerged macrophytes (Sagittaria pygmaea Miq, Hippuris vulgaris., Limnophila heterophylla) on five eutrophic algae Chlamy domonas sajao、Microcystis aerugnasa、Phormidium tenue、Scenedesmus quaclricauda、Chlorella pyrenoidosa are investigated by the form of adding planted water continuously. The research results indicate that: (1) The planted water of Sagittaria pygmaea Miq inhibited the growth of Chlamy domonas sajao and obviously accelerated the growth of Chlorella pyrenoidosa , but it has no effect on the growth of Microcystis aerugnasa、Scenedesmus quaclricauda and Phormidium tenue. (2) The planted water of Hippuris vulgaris inhibited the growth of Microcystis aerugnasa and obviously accelerated the growth of Scenedesmus quaclricauda, but it has no effect on the growth of Chlorella pyrenoidosa、Chlamy domonas sajao and Phormidium tenue. (3) The planted water of Limnophila heterophylla inhibited the growth of Chlorella pyrenoidosa、Scenedesmus quaclricauda and Phormidium tenue, without any effect on Microcystis aerugnasa, but accelerated the growth of Chlamy domonas sajao. Of the three submerged macrophytes, Limnophila heterophylla has the strongest inhibition on Eutrophic algae, and has wider allelopathic effects. Limnophila heterophylla compete with algae more predominant, and it should be used to inhibit excessive growth of algae in Eutrophic water body.