روح الله افریکان

In the whole agro ecosystems, weeds had existence as unwanted plant that control of them is necessary. The competition between weeds and corn for moisture, light, nutrients during the growth season is induced reducing the quality and quantity of corn yield. Although the corn is high and powerful crop but is sensitive to competition with the weed and reduction of yield has been reported over 30%. Since the weeds are adapted to conditions, they are successful to completion and reducing the yield. So weed management is important in corn production. Chemical control has not been the unique and best way to manage the weeds and it reduce the sustainability of agro ecosystems. Although developing the herbicides, reduce the pressures caused by the weeds, but by developing rapidly the weed resistance to herbicides and increasing the environmental concerns and its high cost, today need to new, more immune and sustainable techniques for weed management. The main approach for sustainable weed management in an integrated weed management program is increasing crop competitiveness with weeds to reduce herbicide use. In this regard, the planting date, crop rotation, planting density, intercropping, planting pattern, fertilizer type, rate and application method are some of the most crop management strategies. Among the nutrients necessary for plants, nitrogen is the most nutrient in plant competition. Therefore, its application management plays a key role in reducing weed interference with crops and reduced herbicide use. Foramsulfuron herbicide from ALS inhibitors is a post-emergence sulfonylurea herbicide for the control of grasses and certain broadleaf weeds in maize. Unfortunately, these herbicides are also notorious for their ability to select resistant weed populations. Now, there are more weed species that are resistant to ALS-inhibiting herbicides than to any other herbicide group. In several cropping systems, ALS-inhibiting herbicides were used repeatedly as the primary mechanism of weed control. These herbicides exert strong selection pressure because of their high activity on sensitive biotypes at the rates used and because of their soil residual activity. So, the primary objective of this study was to determine the effect of some crop management strategies including sowing pattern and fertilizer application methods on herbicide optimizing and reducing foramsulfuron dose.
In order to evaluate the effects of corn sowing pattern and nitrogen application methods on optimizing and reducing of foramsulfuron dose, a field experiment was conducted as split factorial, based on randomized complete block design with three replications at the Research Station, of Faculty of Agriculture, Ferdowsi University of Mashhad, in 2012. Treatments included, corn sowing methods (single-row with 75 cm distance, twine row as parallel on 75 cm width ridges sides and double row as zigzag on 75 cm width ridges sides) as main plots, factorial of nitrogen application methods (broadcast and band application), nitrogen source for fertilization was urea (400 kg ha-1), and foramsulfuron doses (100, 75, 50 and 0% of recommended dose (2 liter of commercial doses) applied at 4th corn leaf stage as sub plots.Weed density and frequency were recorded 10 days before corn harvesting and total weed biomass, corn biomass and seed yield were recorded at the end of the experiments per 1 m-2. Analysis of variance of data was carried out with SAS software and for means comparisons LSD (p≤0.05) test was used. Also The rectangular hyperbolic equation to describe the relationship between density and weed biomass and biomass and grain yield of maize was used
Evaluation of weed flora indicated that 6 weed species (including 5 dicot. and 1 monocot.) including red root pigweed (Amaranthus retroflexus L.), black nightshade (Solanum nigrum L.), lambsquarters (Chenopodium album L.), field bindweed (Convolvolus arvensis L.), purslane (Potulaca oleracea L.) and barnyard (Echino clhloacrussgalli L.) were dominant species, with high evenness in the experimental plots. Amongst the mentioned weed species, the red root pigweed included about 74% of relative frequency and 80% of relative biomass of total weed biomass. Also results showed that the effect of sowing pattern on biomass and density of weeds and corn traits was not significant. However, band application of nitrogen versus broadcast application, increased weed density and biomass per m-2 25 and 10 percent, respectively and in the same way, increased corn height, kernel yield and biomass per m-2 7, 30 and 25 percent, respectively.
It was concluded that by using double row sowing pattern along with band application of nitrogen, we can reduced foramsulfuron dose nearly 50 percent.

Wheat is the main crop cultivated through out the world. Around 60 percent acreage of world farms belong to cereal crops from which, 33 percent belong to wheat production. In Iran wheat also is the dominant cereal crop accounting for almost 70 percent of cereal production. Iran wheat production in 2013 was about 14 million tones, and average grain yield 3750 Kg ha-1, is much lower than developing countries such as France ( 6800 Kg ha-1 ), Germany (7000 Kg ha-1 ) UK (7500 Kg ha-1 ) Japan ( 5000 Kg ha-1 ) and China (4900 Kg ha-1. The reasons for low yield include conventional planting methods, costly inputs, improper land preparation, imbalanced fertilizer application, lack of coordination between growers and mill owners, natural calamities and shortage of irrigation water and heavy weed infestation. Among these, poor management of fertilizers and weeds are the major cause of low wheat production in Iran. The use of herbicides for weed control in wheat is a common practice in management of weeds. But environmental and economical aspects, uncertainty in the long-term efficacy of chemical weed control methods are the most important issues that have caused researchers and farmers seeking to introduce an alternative to herbicides or to reduce the use of herbicides. Among herbicides, sulfonylurea’s such as sulfosulforun is one of the most important herbicides in wheat field. However, sulfosulforun is an effective herbicide for weed control. But its active soil residual, may damage rotational crops. Due to importance of nitrogen fertilizer management in wheat yield improvement, present study was designed to investigate the effect of nitrogen fertilizer application methods on weed management of wheat and reducing sulfosulforun herbicide under agro-climatic conditions of Mashhad, Iran.
In order to evaluate sulfosulforun reducing dose, by nitrogen application management, an experiment was performed as split factorial plot, based on randomized complete block design with three replications at research farm, Faculty of Agriculture, Ferdowsi University of Mashhad, in 2012. Treatments included, nitrogen application methods (Broadcast and Band), the amount of nitrogen application (100, 200 and 400 kg ha-1 )(46% urea source) equal to 46, 92 and 184 kg ha-1 nitrogen per hectare, as complete factorial plots and sulfosulforun doses (100, 75 and 50 % of recommended dose (26.6 g (75% EC (emulsifiable concentrate)) as sub plots, applied at wheat tillering stage. Weed density and relative frequency were recorded 149, 177 and 210 days after wheat planting. Wheat biomass and seed yield per 1 m-2 were recorded at the end of the experiments. Analysis of variance of data was carried out with SAS software and for means comparison LSD (p≤0.05) test was used.
Results showed that band application of nitrogen, reduced weed density and weed biomass significantly. By increasing nitrogen dose, mentioned parameters were increased significantly in both methods on nitrogen application. The highest weed density (29.27 plant m-2) were observed when sulfosulforun was not applied and the method of nitrogen application was broadcasted. The lowest weed density (12.78 plant m-2) observed at solfosulforun recommended dose and nitrogen band application treatment. The method of nitrogen application affected the amount of solfosulforun application. Based on the results, the effect of sulfosulforun at 75% and 50% of the recommended dose, didn’t effect significantly (p 0.05) on weed control when nitrogen applied in band with solfosulforun at recommended dose on weed control when nitrogen applied broadcast. Similar results were observed for wheat seed yield and wheat biomass. Wheat seed yield (343.40 g m-2) and wheat biomass (1141.50 g m-2) at solfosulforun recommended dose, when nitrogen applied in band, was not significantly different from 75% recommended dose of solfosulforun and nitrogen broadcast application method.
Based on the results of experiment, the amount of nitrogen and its application method concludes an acceptable approach for wheat integrated weed management. It can optimize nitrogen fertilizer and solfusulforun herbicide usage, which are the main concerns in wheat production economically and ecologically. However nitrogen band application reduced the amount of nitrogen fertilizer and solfusulforun herbicide. Due to various factors affecting the competitive relationship between weeds and crops, it is suggested that in future the use of other herbicides, in different places and different crops to be considered.

Spinach (Spinacia oleracea L.) is a quick-maturing, cool-season, hardy vegetable crop that is produced for both fresh markets (field packed in bunches or lightly processed in cellophane bags) and processing markets (frozen products). A fresh-market spinach can be grown in 30 to 50 days, while the same variety grown for freezer processing takes 70 to 120 days. Spinach require weed control from nearly the moment a gardener decides to plant them, extending throughout the growing season. Weeds are often the most serious threat for organic vegetable production. Therefore weed control is especially important at the early growth of them. Two recent trends in agriculture have encouraged to use alternative weed control methods instead of chemical control (Cordill and Grift, 2011). Soil solarization is a nonchemical method to control soilborne pests in which high temperatures produced by capturing the sun radiant energy. The method involves heating soil by covering it with a clear plastic tarp during a hot period of year when soil will receive the most direct sunlight. Another method is use of cover cops. Cover crop help to maintain soil organic matter, improve soil fertility, prevent erosion and assist in nutrient management. They can also contribute to weed management, increase water infiltration, and maintain populations of beneficial fungi. Therefore, this research was conducted to evaluate the effect of different weed management methods on the weed seed bank and growth characteristics and fresh weight of spinach based on principles of sustainable agriculture. A field experiment was performed at the Agricultural Research Station Field of Ferdowsi University of Mashhad in growing season 2012-2013. Seven treatments including solarization using by dark and transparent sheets, three crop residues, sunflower (Helianthus annuss L.), barley (Hordeum vulgare L.) and garlic (Allium sativum L.), hand weeding and weed-infest control were arranged based on a randomized complete block design with three replications. Before the start of experiment, soil seed bank was sampled from the soil depth of 0-30 cm. Seed bank samples were conducted at two stages including before land preparation and after harvest times. Weed seed were pulled out from the soil depth of 0-20 cm and recognized by stereomicroscope. Yield of spinach was determined at the end of the growing season. Plant height, leaf area index (LAI), as well as dry and fresh weight were measured in five randomly selected plants. Data were subjected to the analysis of variance (ANOVA) using MSTAT-C. Significant difference among means were identified by Least Significant Difference (LSD) at the 0.05 level of significance.. In this experiment, the weed community of seed bank was comprised for 7 species. The results showed that solarization and use of cover crops significantly affected seed number of weeds on the seed bank (p≤0.01). The minimum and maximum relative density ranges were observed for amaranth (Amaranthus sp.) and barnyard grass (Echinochloa crus-galli L.) with 5.26-25.00 and 22.00-70.00%, respectively. Although decreasing of identified weed seed number affected by non-chemical treatments compared to control, but the highest rate of decrease (93%) was recorded in solarization with dark polyethylene. The impact of non-chemical management treatments was significant (p≤0.01) on growth characteristics and yield of spinach. The highest and the lowest fresh weight of spinach were observed for solarization with dark polyethylene (1921.3 g.m-2) and control plot (413.3 g.m-2), respectively. Application of garlic, barley and sunflower residues improved the fresh yield of spinach up to 41, 55 and 63% compared to control, respectively. These improvements were 75% and 78% for solarization with transparent polyethylene and hand weeding, respectively. Dark polyethylene enhanced growth characteristics and yield of spinach due to controlling of weeds, temperature regulating and improving moisture content of soil. Impact of solarization with dark sheets on seed bank, growth characteristics and yield of spinach was higher than transparent sheets. Crop residue application enhanced growth characteristics of spinach due to their positive effects on soil properties. So, based on the results of the present study solarization with dark and transparent sheets is an effective approach for weed control and improving growth characteristics of spinach.