Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 52 1 2021 03 21 Does increase of wild oat density change time of application of wheat selective herbicide? Does increase of wild oat density change time of application of wheat selective herbicide? 131 143 80991 10.22059/ijfcs.2020.295226.654678 FA Ahmad Zare Plant Production and Genetics Department, Faculty of Agriculture, Agricultural Sciences and Natural Resources University of Khuzestan 0000-0003-2505-6134 Hamid Rahimian Mashhadi Agronomy and Plant Breeding Department, Faculty of Agriculture, University of Tehran Mostafa Oveisi Agronomy and Plant Breeding Department, Faculty of Agriculture, University of Tehran 0000-0003-0742-5485 Reza Hamidi Agronomy and Plant Breeding Department, Faculty of Agriculture, University of Shiraz Journal Article 2020 01 05 To investigate the effrct of various densities of wild oat, application time and type of herbicide on wild oat control and yield and yield components of wheat, a split spilt plot experiment was carried out base on randomized complete block design (RCBD) with 3 replications in a field in Fars Province )Marvdasht city) in the cropping year of 2014-2015. The different densities of wild oat (0, 20, 40, 80, 160 and 320 plants m²) as the main plot, two herbicides including mesosulfuron + iodosulfuron + mefenpyr-diethyl (Atlantis18 g a.i. /ha) and clodinafop-propargyl (Topik, 64 g a.i. /ha) as sub-plot and application time (18 (8 leaves) and 23 Zadoks (tillering) stages) as sub-sub plot were considered. According to logistic model (parameter Den₅₀), 127 and 95 wild oats per m² was required to reach a 50% reduction in dry weight of wild oat in clodinafop-propargyl herbicide treatment at 8 and 23 Zadoks stages, respectively, whereas, for 50% reduction in dry weight of wild oat in mesosulfuron + iodosulfuron herbicide treatment were 141 and 149 wild oats/m², respectively. The regrowth of wild oat in clodinafop-propargyl compared to mesosulfuron + iodosulfuron herbicides was higher in tillering compared to 8 leaves in all densities. Hyperbolic model for grain yield showed that in Topik herbicide treatment at both application times, 50% reduction in the yield was observed in 118 and 83 wild oats/m² and in mesosulfuron + iodosulfuron herbicide treatment at both application times, 50% reduction in the yield was observed in 423 and 221 wild oats/m².At higher wild oat densities, of mesosulfuron + iodosulfuron application is recommended at 18 Zadoks stage. To investigate the effrct of various densities of wild oat, application time and type of herbicide on wild oat control and yield and yield components of wheat, a split spilt plot experiment was carried out base on randomized complete block design (RCBD) with 3 replications in a field in Fars Province )Marvdasht city) in the cropping year of 2014-2015. The different densities of wild oat (0, 20, 40, 80, 160 and 320 plants m²) as the main plot, two herbicides including mesosulfuron + iodosulfuron + mefenpyr-diethyl (Atlantis18 g a.i. /ha) and clodinafop-propargyl (Topik, 64 g a.i. /ha) as sub-plot and application time (18 (8 leaves) and 23 Zadoks (tillering) stages) as sub-sub plot were considered. According to logistic model (parameter Den₅₀), 127 and 95 wild oats per m² was required to reach a 50% reduction in dry weight of wild oat in clodinafop-propargyl herbicide treatment at 8 and 23 Zadoks stages, respectively, whereas, for 50% reduction in dry weight of wild oat in mesosulfuron + iodosulfuron herbicide treatment were 141 and 149 wild oats/m², respectively. The regrowth of wild oat in clodinafop-propargyl compared to mesosulfuron + iodosulfuron herbicides was higher in tillering compared to 8 leaves in all densities. Hyperbolic model for grain yield showed that in Topik herbicide treatment at both application times, 50% reduction in the yield was observed in 118 and 83 wild oats/m² and in mesosulfuron + iodosulfuron herbicide treatment at both application times, 50% reduction in the yield was observed in 423 and 221 wild oats/m².At higher wild oat densities, of mesosulfuron + iodosulfuron application is recommended at 18 Zadoks stage. https://ijfcs.ut.ac.ir/article_80991_66cc5608a851eba2cf95aaeefe595b03.pdf