Determination of optimum concentration of Diuron for the growth and bloom of the algae (Scenedesmus obliquus) in in Vitro condition

Growth rate of the green algae, Scenedesmus obliquus, influenced by Diuron, with the trade name of (Karmex) and chemical name of (N'-(3,4-Dichlorophenyl)-N,N-Dimethylurea), was examined in the present study. This study is performed in the laboratory of National Inland Waters Aquaculture Institute in Iran during 96 hours in 6 treatment and 3 replicates, using 500 cc Erlenmeyer Flasks. Measurement of growth rate in the same period of time was performed by three simultaneous methods of cell counting, measurement of turbidity and determination of the rate of chlorophyll a. Quantities of EC10, EC50, EC90 and allowable concentration level of this poison for the studied algae were obtained as 0/0019, 0/1, 0/05, 0/02 milligram per liter, respectively. Achieved quantities of EC were used in four 500cc Erlenmeyer flasks each containing more than one million algae cells and in 24h periods adding up to be 96 hours, concentration of the algal cells was evaluated by cell counting. Results of the present experiment showed that the frequency of S. obliquus was significantly different in presence of concentrations obtained from EC indicators and decreased sharply in EC90 quantities.