study of nicosufuron+rimsulfuron (ultima) residues in maize filed by bioassay

one of the most important adverse environmental effects of herbicide application in production systems is possible damage to non-target plants, such as crops that are grown in rotation. nicosufuron+rimsulfuron (ultima) is a sulfonylurea herbicide that recently registered for use in maize fields in iran. its residues may be present more than a season in certain conditions. to measure nicosufuron+rimsulfuron residues, a greenhouse experiments were performed based on randomized complete block design in karaj, fasa and moghan. at first, the sensitivity of eight plant species (wheat, barley, bean, lentil, vetch, canola, sugar beet, and cucumbers) to nicosufuron+rimsulfuron was determined using a completely randomized design. lentil with the maximum inhibition of root length was detected as the most sensitive plants to the herbicide. thus, it was used in bioassay trials to determine the concentration of the herbicide in the maize field. the determination of nicosufuron+rimsulfuron residues using standard regression equations showed that at the recommended dose of herbicide residues were detected up to 60 days after application. based on the model parameters, x0 (time required for 50% dissipation of the herbicide) in fasa was less than the other two regions, a 34.7% and 56.8 % decrease compared to karaj and moghan, respectively. thus, in areas where corn is rotated as a second crop and its weed are controlled by ultima, considering the suitable re-cropping interval   to reduce the adverse effects of this herbicide on the next plants is necessary.