بررسی اثر کاربرد ترکیبی علفکشهای پیشکاشت و پسرویشی بر عملکرد و اجزای عملکرد گندم.

Background and Objectives: Wheat (Triticum aestivum L.) is one of the most strategic crops, which is very important in terms of level and nutritional value, and is known as one of the most important and most consumed crops in the world. According to the report of the World Food and Agriculture Organization (FAO), in 2017, the world production of wheat was about 772 million tons, of which Iran's share was reported to be about 14 million tons. Increasing the yield of wheat per unit area depends on certain factors, one of which is the correct management of weeds to reduce their damage. Therefore, the aims of this study was to use different time of application of pre and post emergence herbicide to reduce use of herbicide for improving productivity of wheat. Materials and Methods: A field experiment was conducted in a randomized complete block design with three replications in the research farm of Shahid Chamran University of Ahvaz in the year 2019-2020. Treatments in this experiment include; Uncontrolled, hand weeding, pendimethalin + atlantis, pendimethalin + metribuzin, trifluralin + atlantis, trifluralin + metribosin, pendimethalin + 2,4-D, trifluralin + 2,4-D, green mungbean + 2,4-D and 2,4-D intercropping. Wheat cv. ‘Mehregan’ was sown at 20 cm row spacing on 28 November in 2019. A seed rate of 120 kg ha-1 along with recommended fertilizer dose of 120:60:40 kg N-P2O5- K2O ha-1 was followed uniformly. Wheat matured in the 2nd week of April. Result: The control methods of hand weeding and pendimethalin+atlantis had a positive effect on increasing the weight of 1000 seeds and the treatment of trifluralin+2,4-D had a negative effect on the weight of 1000 seeds. Examining the changes in wheat grain yield among weed control levels showed that hand weeding and pendimethalin+Atlantis treatment levels had an average grain yield of 3.86 and 3.93 tons per hectare, respectively, which was more than the control, but in the rest of the experimental treatments, lower grain yield was observed. According to the obtained results, the use of pendimethalin pre-planting herbicide along with atlantis herbicide and metribuzin increased yield compared to the control treatment and the use of trifluralin herbicide. Conclusion: In general, the results of this research showed that hand weeding treatments, pendimethalin+atlantis, pendimethalin+metribuzin, improved the growth and performance characteristics of wheat by reducing the amount of weed interference and increasing the amount of absorption of nitrogen, phosphorus and potassium elements in aerial organs. [ABSTRACT FROM AUTHOR]