Abstract

The amount of weed control not only depends solely on the use of herbicides, but also on interactions with other inputs, including the interaction of herbicides and levels of urea fertilizers. In order to study wheat -Sinapis arvensis and Avenaludo viciana competition in response to urea fertilizer and herbicide, a field experiment was laid out in split plots in randomized complete block design with four replications at Agricultural Sciences and Natural Resources University of Khuzestan, Iran. Main plot comprised of urea fertilizer with 5 levels of 0, 45, 90, 180 and 330 kg/ha of urea and herbicide dose of “mesosulfuron methyl + iodosulfuron methyl sodium + diflufenican + mefenpyr-diethyl” Branded (Othello OD) in 6 doses of 0, 0.32, 0.64, 0.96, 1.28 and 1.6 L/ha (recommended dose 1.6 L/ha) as sub plot. The results showed that the response of weed and wheat biomass to herbicide doses was described, respectively, with dose-response and sigmoid models, and developed in response to an increase in urea fertilizer consumption. Based on the prediction of the combined model, the dosage required for reducing the weed biomass to less than 150 g/m2 with consuming of 0, 45, 90, 180, 250 and 330 kg/ha of urea fertilizer was predicted to be 0.64, 1.04, 1.12, 0.96, 0.88, and 0.80L/ha of herbicide, respectively. From the results it could be observed that 1172 g/m2 of wheat biomass can be achieved using 225 kg/ha of urea fertilizer plus 0.96 L/ha.