In order to investigate physiological and biochemical changes of wheat under stress residue of Imazethapyr herbicide (Imazethapyr), an experiment was conducted in a completely randomized design with four replications in greenhouse conditions at university of Mohaghegh Ardebili. The treatments consisted of five dose levels of herbicide Imazethapyr (0, 0.011, 0.022, 0.033 and 0.044 micrograms of herbicide) per kilogram of soil. The analysis of variance showed that the content of the main and auxiliary pigments of leaf, proline, sugar content, protein, activity of catalase enzymes, peroxidase, polyphenol oxidase, root and shoot dry weight were significantly affected by herbicide. The results showed the Imazethapyr herbicide stopped the production of valine leucine and isoleucine amino acids. As a result, the rapid reduction in the volume of these amino acids led to a reduction in protein synthesis in wheat plant. Therefore, the application of doses of 0.011, 0.022, 0.033 and 0.044 micrograms of herbicides decreased 14, 26, 44 and 47 percent of leaf protein content, respectively, compared with control treatment. Further, theapplication of these doses resulted in the reduction of 2.8, 5, 27 and 64% of activity of catalase enzyme, 3.5, 39, 49 and 52% peroxidase enzyme activity and 13, 24, 35 and 46% activity of polyphenol oxidase enzyme, compared with control treatment. The results revealed that Imazethapyr herbicide activates wheat antioxidant enzymes to reduce plant tolerance from damage caused by herbicide residues; therefore, it can be used as a marker or index of herbicide damage rate in physiological research.

In order to investigate the effect of weed control with common herbicides on yield and yield components of soybean ( Glycine max L.) Williams cultivar, two experiments were conducted using randomized complete block design with three replications at Agricultural and Natural Resources Research Center of Moghan during 2016-2017 and 2017-2018. Treatments consisted of Ethalfluralin, Imazethapyr, Trifluralin, Metribuzin, Bentazone and Alacolor herbicides with and without hand weeding control. The results showed that the number of pods per plant, biological yield, grain yield, and soybean protein percentage were statistically significant, but for plant height, growth period, chlorophyll index, 1000 seed weight and oil percent grain, the difference was not significant. The highest number of pods per plant (333.92), biological yield (1221 g.plant -1 ) and grain yield (2792 kg.ha -1 ) were obtained in hand weeding treatment. The results of the analysis of variance showed that the treatments had a significant difference in terms of herbicide efficiency percentage, density, and total weed dry weight. The results showed that one month after spraying, Trifluralin and Ethalfluralin herbicides had the highest effect on weed control. However, two months after herbicides spraying; all other treatments also showed their control effect. In this study, all weed control treatments significantly reduced the density and dry weight of weeds as compared to control treatment, but their effect was less than hand weeding. The highest grain yield (1896 kg.ha -1 ) and the highest biological yield (784.9 kg.ha -1 ) were observed in Ethalfluralin herbicide. Generally, based on the results of this study, the application of Ethalfluralin herbicide at rate of 2 L.ha -1 could be recommended for effective weed control in soybean production systems.

The use of cover crops can be considered as an effective method in sustainable agriculture through reducing herbicide use, improving soil and increasing crop yield. An experiment was conducted using randomized complete block design with three replications in Agricultural and natural resources research center of Ardabil (Moghan) in 2015-2016. Cover crops was considered as the main factor (mixed wheat + crimson clover, monoculture wheat and mixed (rye + wheat)) and mulch management as subplots and control (no cover crop use post-emergence herbicide Maister (Foramsulfuron + Idosulfuron 3.1% OD)). The results showed no significant difference between treatments in terms biomass production, the lowest weed biomass was related mixed of rye + wheat in both crop management methods. In wheat and wheat+ rye a significant decrease was observed in crop yield components possibly due to the release of allelopathic materials and soil properties, But the crimson clover mix of wheat + maize yield satisfactory beside weed control a good yield was obtained after the treatment with herbicide. The results showed that the effect of cover crop, crop management and their interaction except grain weight, were significant for ear dry weight, biological yield, number of rows per ear and number of kernels per ear. The highest values of grain yield, ear dry weight, biological yield, number of grains per ear was achieved in treatments clover + wheat and the least amount of yield and yield components of treated wheat were obtained in residues removed management.