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Application possibility of non-selective soil herbicides to weed control in wheat was studied in a two-year experiment in 2022 and 2023 in East Azerbaijan (Maragheh) and Khorasan Razavi (Torgh, Mashshad), Iran. The experiment was established in a conservation agriculture setting, utilizing a strip-plot design based on a randomized complete block design with four replications. The vertical treatment included the application of herbicides, while the horizontal treatment involved different speeds of planter (5 and 7 kilometers per hour). The herbicides were Terflan (trifluralin EC 48%, at 1.5 and 2 L.ha-1) and Sencor (metribuzin WP 70%, at 500 and 700 g.ha-1). Additionally, three control treatments were implemented: clodinafop-propargyl + 2, 4-D + MCPA (post emergence at rates of 1000 + 1500 mL.ha-1), weed free and weed infested. Evaluations were conducted 30 days after spraying and included assessments of weed density and biomass, as well as the dry weight and yield of wheat at the end of the growth period. Based on the experimental results in Khorasan Razavi, speed of planter did not have a significant effect on weed density and dry weight, as well as on the germination, growth, and yield of wheat in either year. In contrast, the total weed density and dry weight were reduced by 25% and 17%, respectively, due to the application of pre-emergent herbicides in the first year compared to the untreated control. The differences among herbicides were not also significant. Similarly, the application of pre-emergent herbicides showed a comparable effect on total weed density and dry weight, with no significant impact compared to the untreated control in Mashhad. In the Maragheh region, the application of metribuzin at a rate of 700 g.ha-1 demonstrated superiority with an average total density of 1.9 plants.m-2 and a dry weight of 1.43 g.m-2 compared to the untreated control (with an average of 2.4 plants and 1.74 grams per square meter), and was identified as the best treatment. In the second year, regarding total weed density, the pre-emergent herbicide treatments did not show significant differences among themselves but reduced total density by 31% compared to the untreated control. In this year, the combination of clodinafop-propargyl + 2,4-D + MCPA was the most effective treatment, leading to a 93% reduction in overall density. In Maragheh and during the second year, metribuzin (at 700 g.ha-1) reduced total weed dry weight by 47.5%, while clodinafop-propargyl + 2,4-D + MCPA led to a 95% reduction compared to the untreated control. According to the assessment of herbicide treatments in Khorasan Razavi during the first year, the biological yield of wheat did not differ significantly from weed free control, although the average grain yield in pre-plant herbicide treatments decreased by approximately 22%. Among these treatments, no significant differences were observed. In the second year, the grain yield of wheat in treatments of trifluralin at a rate of 1.5 L.ha-1 and metribuzin at 500 g. ha-1 (with average yields of 3.58 and 2.81 ton. ha-1, respectively) did not differ significantly from the weed free control (with an average yield of 2.99 ton.ha-1). In the Maragheh region, the impact of pre-plant herbicides on wheat was not well assessed in the first year, and due to the dryland conditions in this area, the damage to wheat plants was noted, with reductions in dry weight of 24% for trifluralin and 70% for metribuzin, followed by decreases in grain yield of 13% for trifluralin and 42% for metribuzin. In the second year, with adjustments made to the treatments, better results were achieved such that the grain and biological yield of wheat in the split-application doses of metribuzin (at 250+250 grams before planting and at the full tillering stage) did not differ significantly from the weed free control. Thus, the application of this herbicide using the specified method may be recommended, pending validation in pilot studies.
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