Abstract

Understanding the interaction between crop-weed competition and herbicide doses may, in many cases, result in a recommendation to reduce the consumption of the herbicide, which is both environmentally and economically important. Nitrogen fertilizer also influences the competitive balance through changes in weed density and biomass, and also contributes to environmental pollution. Hence, the evaluation of the interaction of herbicide doses and nitrogen fertilizer application is necessary for proper management of weeds and achieving acceptable economic yield along with minimizing environmental negative impacts.Therefore, in order to Quantify wheat-weed competition to levels of urea and reduced dose of herbicide (mesosulfuron methyl + iodosulfuron methyl sodium + diflufenican + mefenpyr-diethyl) brand (othello OD) this experiment was conducted during 2019–20 at Khuzestan University of Agricultural Sciences and Natural Resources, Iran. The experiment was laid out in split plots under randomized complete block design wherein urea fertilizer included five levels of 0, 45, 90, 180 and 330 kg/ha as the main plot and the herbicide dose of “othello OD” in six levels of 0, 0.32, 0.64, 0.96, 1.28 and 1.6 L/ha (1.6 L/ha the recommended dose) was considered as the sub plot. The results showed that wheat grain yield and weed biomass response to herbicide doses of sigmoid response and response dosage models, and developed in response to an increase in urea fertilizer consumption. Based on the prediction of the combined model, The achieving a yield of about 500 g/m2 with the application of 140 kg of urea fertilizer per hectare with 1.04 L/ha of Othello OD herbicide or the application of 265 kg of urea fertilizer per hectare and 0.64 L/ha. Hectare of herbicide or application of 330 kg urea fertilizer per hectare with 0.72 L/ha of herbicide was possible.