Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 54 1 2023 03 21 Evaluation of radiation absorption and use efficiency of winter wheat (Triticum aestivum L.) and wild oat (Avena ludoviciana L.) in nitrogen fertilizer levels and wild oat additive densities Evaluation of radiation absorption and use efficiency of winter wheat (Triticum aestivum L.) and wild oat (Avena ludoviciana L.) in nitrogen fertilizer levels and wild oat additive densities 59 79 92707 10.22059/ijfcs.2022.338838.654894 FA Ashkan Kalilian Department of Production Engineering and Plant Genetics, Razi University, Kermanshah, Iran. Farzad Mondani Department of Production Engineering and Plant Genetics, Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran Alireza Bagheri Dept. of Production Engineering and Plant Genetics, Faculty of Science and Agricultural Engineering, Razi University, Kermanshah-Iran Mahmoud Khorrami Vafa Department of Agronomy and Plant Breeding, Faculty of Agriculture and natural resources, Razi University, Kermanshah, Iran Journal Article 2022 02 09 Some essential factors effectively reduce wheat yield; one of the most critical factors is weeds. The effect of this factor can vary at different fertilizer levels. To investigate the effect of different densities of wild oat in different nitrogen fertilizer levels on the wheat traits, an experiment was conducted in the form of split plots and in a randomized complete block design with three replications. Treatments included the application of 30, 60, 100 and 120% of wheat nitrogen fertilizer requirement and densities of zero, 25, 50, 75 and 100 wild oat plants per m². The results showed that the highest wheat grain yield (871.60 g/m²) and radiation use efficiency (1.49 g Mj^-1) obtained at 120% fertilizer level and the absence of weeds, and the lowest obtained at 30% nitrogen and 100 plants per m². The highest dry weight yield (381 g/m²) and radiation use efficiency (1.6 g Mj^-1) of wild oats were obtained at 100 plants/m² density and at the highest level of nitrogen fertilizer. In general, increasing the presence of wild oats and increasing its density under conditions of improper application of nitrogen can intensify interspecific competition and ultimately lead to yield reduction. Some essential factors effectively reduce wheat yield; one of the most critical factors is weeds. The effect of this factor can vary at different fertilizer levels. To investigate the effect of different densities of wild oat in different nitrogen fertilizer levels on the wheat traits, an experiment was conducted in the form of split plots and in a randomized complete block design with three replications. Treatments included the application of 30, 60, 100 and 120% of wheat nitrogen fertilizer requirement and densities of zero, 25, 50, 75 and 100 wild oat plants per m². The results showed that the highest wheat grain yield (871.60 g/m²) and radiation use efficiency (1.49 g Mj^-1) obtained at 120% fertilizer level and the absence of weeds, and the lowest obtained at 30% nitrogen and 100 plants per m². The highest dry weight yield (381 g/m²) and radiation use efficiency (1.6 g Mj^-1) of wild oats were obtained at 100 plants/m² density and at the highest level of nitrogen fertilizer. In general, increasing the presence of wild oats and increasing its density under conditions of improper application of nitrogen can intensify interspecific competition and ultimately lead to yield reduction. https://ijfcs.ut.ac.ir/article_92707_aa9fb615e1ff0fb14699cb35bf59565e.pdf