Bioassay of Chlorsulfuron Residue in Soil by Using Cress (Lepidium sativum L.) Plant as an Indicator

M.Sc Student, Pardis Faculty of Agriculture and Animal Science, Tehran University, Iran 2- Ph.D Student, Pardis Faculty of Agriculture and Animal Science, Tehran University, Iran Received:11 Nov. 2007 Accepted: 7 Feb. 2008 ABSTRACT Chlorsulfuron is a herbicide which shows carry over effects. Their residues may damage subsequent crops presented in rotational program. Bioassay is considered a good method for detecting biologically active herbicide residues. A greenhouse experiment using cress Lepidium sativum L. as an indicator plant was conducted to detect the bioavailable residues of Chlorsulfuron (at 0 – 0.125 ppm) in a completely randomized design in research greenhouses of Karaj College of Agriculture, during the summer of 2006. The models of three and four parametric log-logistic described plant shoot, dry weight and height response as a function of herbicides doses. Chlorsulfuron its lowest concentration (0.025 ppm) reduced dry weight and height of cress significantly. ID20 (The Doses which caused to decrease 20% of plant dry weight) of chlorsulfuron for plant dry weight and height were 0.023 and 0.047 ppm, respectively. In general, plant dry weight and height of cress show adequate sensitivity to detected chlorsulfuron. Cress germination was not affected by either herbicide or the applied doses. Keywords: Indicator plant, Carry over, Bioassay, Herbicide, Chlorsulfuron _____________________________________________________________________________________________