Inhibitory Effects for Water Extracts from the Root of Geum aleppicum Jacq. on Scenedesmus obliquus

The inhibitory effects of an allelopatbic fraction extracted from the root of Geum aleppicum Jacq. The growth status of Scenedesmus obliquus was investigated when different amounts of the allelopathic fraction (i.e. water extracted from the the Root of Geum Aleppicum Jacq.) were added into the culture solution, in which the same amount of algae was inoculated. During the cultivation period, the algae cell density was determined by hemocytometer under a microscope and the changing shape of algae was also observed under a transmission electron microscope. The results indicated that the allelopathic fraction showed significant inhibitory effects on the growth of Scenedesmus obliquus, and the half-effect concentration EC_50,7d was 3.8 g/l. The algae cells with the treatment of allelopathic fraction became well-rounded, dark green colored and it´s settling velocity was speeded up.