e. zeinali

For optimal production and maintaining its stability, environmental and weather conditions must be determined from the perspective of capabilities and limitations. For this purpose, it requires reliable regional data such as planting date, ripening time, plant density, soil, and meteorological information, which are generally not available for most regions. Obtaining this information is very time-consuming and expensive in many areas and is often simply not possible. Therefore, zoning can facilitate access to this information on a large scale. In other words, if the regions that are similar in terms of climate, soil, and management conditions are identified, the time and cost needed to collect information on a wide scale will be minimal.  

The present study was conducted for the agro-ecological zoning of the country. In this research, the existing climatic zones of the country were analyzed based on GYGA, and the existing soil zones of the country were analyzed based on the HC27 method.

The combination of climatic zones and soil, 198 polygons or agro-ecological zones were obtained for all agricultural lands of the country. The zones in which more than 1% of the country's agricultural lands are located include 28 zones, and in total, about 80% of the agricultural lands are located in these zones. The highest frequency percentage is related to agro-ecological zone 4103-5 with a frequency of 85.11%. Also, the frequency of agro-ecological codes (climate code 5003 with soil code 5) 5003-5 (28.7%) and (climate code 4003 with soil code 5) 5-4003 (93.4%) were placed next. Zoning can facilitate the selection of points for plant studies and other planning.

Each of these areas has a different climate and soil code, which indicates the specific production conditions of that area. From these agro-ecological zones, to improve studies and make agricultural management decisions, it is possible to prepare and complete the climate and soil information bank in each zone for use in simulation models of plant production, to facilitate the collection of information (such as management information, cultivar information plant) and the implementation of plant production simulation model to be used in studies related to the food security of the country. The current research was conducted to determine the main agro-ecological areas of agricultural production in the country so that simulation studies and other studies can be carried out in the main production location in each province. Therefore, it is necessary to know where the main production centers of each province were, what kind of climate and soil it has, and which meteorological station is the indicator of that region. In this research, the climate zones of irrigated, rainfed, garden, and pasture lands of the country were determined by using the Giga climate map. Based on this, more than 50% of water lands are located in climates 5003, 4003, 5002, 8003, and 6003, respectively. Also, the rainy lands are located in 4103, 4003, and 3103 climates respectively. Also, by using the HC27 soil map, the soil areas in the irrigated, rainfed, garden, and pasture lands of the country were determined. Therefore, more than 50% of water lands in soil codes 5 and 17; Rainy lands in Kodkhak 5 and 12; Garden lands were located in soil codes 5 and 12 and pastures were located in soil codes 5 and 17. By combining climatic zones and soil zones, agricultural-ecological zoning of the country was done, and finally, 198 zones were obtained. The zones in which more than 1% of the country's agricultural lands are located include 28 zones, in total, about 80% of the agricultural lands are located in these zones (Figure 7). The highest frequency percentage (11.85%) was related to the area with agroe-cological code 4103-5, which covered 1789965.8 hectares of agricultural land. Also, after that, the agro-ecological code 5003-5 has the highest frequency (7.28 percent), which covers 1100599.25 hectares of agricultural land in the country. In this research, after the agro-ecological zoning of the country's agricultural lands, several 198 zones were obtained, and after calculating the area covered by each zone, finally, 28 agro-ecological zones have an abundance percentage of more than 1%, and together they are about 80% (11813518.66 hectares). They cover the country's agricultural lands. These climate zones obtained can be used for food security studies and calculating and determining the production capacity of each region. On the other hand, considering that in agricultural studies, extensive and comprehensive information about climate and soil is needed for each region and access to this information is usually expensive and time-consuming, the use of agro-ecological zones resulting from this research can be necessary.

Contamination of wheat seeds in southern Golestan province (Shahkooh village) with rye has rendered it a weed in wheat fields. Due to the lack of suitable herbicides, it is very difficult for farmers to control weed-rye. According to observations, many farmers use rye-infected self-consumed wheat seeds for cultivation. Separation of rye seeds from wheat seeds is very difficult due to their similarity in appearance, and farmers are not aware of the possibility of seed separation. Therefore, this study was conducted to compare the physical properties of rye and wheat seeds to improve seed separation.

Rye seeds were collected from wheat fields in Shahkooh village. The seeds of Alvand wheat cultivar, which is a common cultivar in Shahkooh region, were also obtained from Shahkooh Rural. The studied physical properties included seed size (seed length, width and thickness), seed surface area, seed weight, spherical percentage, bulk density, true density, porosity percentage, angle of repose and coefficient of friction. Physical properties of the seeds were studied at five seed moisture levels including 10, 15, 20, 25 and 30%.

Based on the results, the length, width and surface area of both wheat and rye seeds were not affected by seed moisture. Only in wheat, seed thickness increased with increasing seed moisture content. Since these properties determine the final seed size, it can be said that the seed size remained almost constant by increasing the percentage of seed moisture in these two plants. On the other hand, in all moisture levels, the width, thickness and surface area of wheat seeds were higher than those of rye seeds. In contrast, seeds length of rye was longer than wheat seeds. In wheat seeds, the spherical percentage increased linearly by increasing seed moisture content, but its amount was constant in rye at different seed moisture content. The significant difference between the spherical percentage of wheat and rye seeds also indicates that the wheat seed is more spherical compared to rye at all moisture levels. The seed weight increased linearly with increasing seed moisture content in both wheat and rye plants, with a higher slope in wheat than rye. In addition, wheat seed weight was higher than rye seed weight in all moisture levels. The existence of these differences in the dimensions, the shape and weight of wheat and rye seeds can be considered as the basis for their separation. In wheat and rye plants, the bulk density, true density and percentage of seed porosity decreased linearly by increasing seed moisture content. Also, the bulk density and true density in wheat was higher than in rye at all moisture levels. With an increase in seed moisture from 10 to 30 percent, the porosity percentage in both wheat and rye plants decreased by about 14 percent on average, and there was no significant difference between them in terms of the percentage of porosity at different moisture levels. An increase in the percentage of seed moisture caused a linear increase in the angle of repose. In other words, the ability of seeds to move was reduced by increasing the moisture content in two wheat and rye plant. There was no significant difference in the angle of repose between wheat and rye at any of the moisture levels. In this study, the coefficient of friction in wheat and rye seeds linearly increased on different materials by increasing seed moisture content. There was no significant difference in the coefficient of friction on galvanized iron and cement surfaces at different moisture levels between wheat and rye. However, the coefficient of friction in wheat was always higher than rye on plastic, wood and rubber surfaces. Due to these differences, it is easy to remove rye seeds from wheat seed lots and prevent rye from re-entering the wheat fields during planting.

According to the results of this study, there is a significant difference between wheat and rye seeds in terms of physical characteristics. These differences facilitate separation of rye seeds and avoid entry into wheat seed lots. The difference in the length, width, thickness and density of the seeds in these plants makes it possible to use length or width based separators, air screen machines and gravity separators.

Repeated tillage, in addition to the burning of post-harvest crop residues in recent decades, has caused various problems, including reduced soil fertility and increased soil water losses, resulting in reduced water use efficiency. To study the effects of type of tillage system and how to manage wheat residues on yield, and cotton water use efficiency, a field experiment was conducted in 2016 and 2017 in a randomized complete block design with four replications in Hashemabad cotton research station of Gorgan was executed. The tillage system consisted of four levels of tillage: no-tillage (NT), conventional tillage (CT), disk (DK), combinate (ComT), and crop residues management of wheat including three levels of complete removal of the remains (CRR), straw removal (SR), and preservation of residues (PR). According to the results, the average total yield in two years of the experiment was 1183 kg/ha in the land preparation with disk (DK) and complete removal of residues (CRR) up to 2563 kg/ha in the land preparation with combinates (ComT) and preservation of residues (PR) was variable. In all tillage systems, the highest yield is related to (PR) and (SR). (CRR) significantly reduced the yield compared with those treatments. Also, the effect of treatments on water use was very similar to their effect on total yield. The average water use efficiency of 0.33 kg / m 3 of water consumed in the treatment of CRR, in addition to conventional tillage (CT) up to 0.77 kg / m3 of water consumed in the treatment (PR) Also, planting with (ComT) was variable. In all soil tillage systems, water use efficiency in the removal of residues was significantly less than the (PR) and (SR). Besides, the results of this study clearly showed that: a) Regardless of the tillage systems, preservation of wheat residue in the soil after harvesting can significantly improve the yield and water use efficiency of cotton, and (b) among the tillage systems, in conventional tillage (CT) system, the lowest yield and water use efficiency are obtained.

Cover crops have  wide range influence on agroecosystem  as well as multiple benefits for farmers. A major benefit of cover crops is the suppression of weeds during fall and winter, which can help to reduce soil tillage and herbicide use. A cover crop is a plant that is used primarily to slow erosion, improve soil health, enhance water availability, make weeds smother, help control pests and diseases, increase biodiversity and bring a host of other benefits to your farm. Many types of plants can be used as cover crops. Fabaceae, Poaceae and brassicaceae familys are the most extensively used. Considering the importance of corn, this study was conducted to investigate the effect of six types of winter cover crops including rye, barley, hairy vetch, berseem clover, Indian mustard and rocket on the dynamics of weed populations and seedling growth and yield of corn.

To investigate  the efficiency of various cover crops in weed controlling, seedling growth and yield of maize (Zea mays L.) (single-cross 704), a factorial experiment based on Split Block  design was conducted with three replicates in 2016-2017 at research field of Gorgan University of Agricultural Sciences and Natural Resources. Experimental treatments included: 1) cover crop type in 7 levels of rye (Secale cereal L.), barley (Hordeum vulgare L.), hairy vetch (Vicia villosa L.), berseem clover (Trifolium alexandrinum L.), Indian mustard (Brassica junce L.), rocket (Eruca sativa L.) and no cover crop (control), 2) weed elimination in two levels of hand weeding and no-weeding. Different  cover crops planted in three times the recommended amount in middle winter of 2016. One week before planting corn, all cover crops were sprayed with paraquat herbicide (3 liters per hectare), then corn seeds were planted  directly inside the residuals of the cover crops manually.

Comparison of weed density and dry weight in various treatments of cover crop with control treatment shows the potential of cover crop (disregarding the type) in weed control and increment of diversity. The results showed that the growth of maize seedlings planted in hairy vetch and berseem clover (both from Fabaceae family) and rye residue areas (form Poaceae family) had an increasing trend and in Indian mustard and rocket (both from Brassicaceae family) and barley (from Poaceae family) had a decreasing trend. The lowest maize grain yield was obtained in no cover crop treatment, whereas the lowest grain yield among cover crop treatments was achieved in maize planted in barley residue. Indian mustard and rocket residues had the lowest maize yield after barley. It seems that residues  of these three crops have  allelopathic impact on maize, which was confirmed by observing growth reduction in maize seedlings planted in these residues. On the other hand, the highest maize grain yield was associated with rye, hairy vetch and berseem clover treatments. Hairy vetch and berseem clover had lower biomass than rye. It seems: 1) the ability of these plants  in biological nitrogen fixation, 2) improve soil fertility and 3) accelerate the rate of decomposition of these plant  residuals had a significant role to  improve the growth and quick development of maize that planted in  residuals of these plants. Brust et al. (2014) were tested the  growth and weed suppression ability of four new cover crop species including tartary buckwheat, forage radish, red oat and grain amaranth. The results show that tartary buckwheat and forage radish are well suited as new cover crops in Germany due to their fast growth and good weed suppression ability. 

According to the results, barley, Indian mustard and rocket are able to produce high biomass and have very good effects on weed control. However these plants also have allelopathic effects on corn seedling. Therefore, they are not recommend for cultivation in corn. Rye, hairy vetch and berseem clover had less biomass, but had a good ability to control weeds. It also improved seedling growth and corn yield. Therefore, these three plants can be described as suitable cover crops in corn.

This study was carried out to evaluate the effects of soil and foliar applied chemical fertilizers and foliar organic acids (as leonardite; a mixture of humic and fulvic acids) on yield and yield components and nutrient uptake by wheat. The experiment was laid out in Gorgan University of Agricultural Sciences and Natural Resources Farm during 2013- 2014, using a split-plot design with four replications. Treatments included potassium application and without potassium in the main plots and foliar applications of nitrogen, potassium, and leonardite from two different sources (Humic Power, mega humat) and a control without foliar application in subplots. Maximum root length before heading was obtained by Humic Power (11.6 cm) and, at harvest, by megahumat (16.4 cm), both in potassium treated sub plots. Root weights also followed the same trend. This may be due to growth stimulating effects of humic acids. Greatest phosphorous uptakes were 19.2 and 48.75 kg.ha-1 by straw and grain, respectively, by foliar application of megahumat in soil potassium applied plots. Foliar applications of nitrogen and potassium also enhanced nitrogen and potassium uptake, respectively. The interactions between foliar and soil applied treatments on stem length and straw yield were significant by analysis of variance. Their combined application significantly improved plant height and straw yield. This research showed that yield by foliar application of leonardite (from both sources) was greater than yield by foliar use of nitrogen and potassium irrespective of soil potassium applications. Soil potassium applications enhanced yield and nutrient uptakes by foliar treatments.

The increasing needs for energy, its high price and its environmental impact on greenhouse gases emission and limited energy resources due to increased research on energy balance in crop production systems. The objective of this research was to compare seedbed preparation and sowing methods in wheat production in Kordkoy region with respect to energy use and efficiency. Fifteen wheat fields were selected in the region in five sites. The fields were classified into three groups with included to seedbed preparation and sowing methods, i.e. centrifuge, drill and Combination Cultivator. All fields were rainfed. The results indicated that using Combination Cultivator method led to 35% and 33% reduction in energy use in seedbed preparation and sowing compared to centrifuge and drill methods, respectively. In terms of energy required for production operations, the method resulted in 22% reduction in energy use compared to centrifuge and drill methods. Using Combination Cultivator also led to 11% and 9% less energy use as seed compared to centrifuge and drill methods, respectively. Energy output to input ratio was 7.41 for Combination Cultivator method which was higher than centrifuge (4.07) and drill (6.15) methods. Using Combination Cultivator also resulted in higher energy yield than other two methods. It was concluded that using (expanding) Combination Cultivator method is effective in energy saving and improving its utilization.

To assess the effects of management factors on nitrogen nutrition and seed yield of rapeseed farms in Gorgan areas, an experiment was conducted as a nested model arranged in a randomized complete block design (RCBD) with three replications in 2010. Fifteen canola fields were classified at three levels of management (optimum, medium, minimum) studied at four growth stages. Questionnaires were filled out by farmers for the quantification of agricultural management levels during the experiment. The results showed that levels of management for nitrogen nutrition index, plant density, dry matter yield, seed yield and harvest index were different significantly (p

Seed dormancy is one of the major problems in the study of the effects of different factors on the weed seed germination characteristics because healthy seeds without dormancy, having high vigor and germinability are needed in these studies. This experiment was carried out to find simple, applicable, cheap, quick and efficient methods to breaking seed dormancy in velvetleaf which is one of the most important weeds in Iran. Two seed populations gathered from two locations in Golestan province were used in this study. Experiments were conducted in a completely randomized design as a factorial with four replications. Each seed population was divided to three parts; the first part (control) was stored in room conditions. The second and the third parts were placed in prechilling conditions (in a cool (4οC) and wet place) for two weeks and three months, respectively. Then, nine mechanical and chemical scarification treatments were applied on each of these 3 seed parts. Treated seeds transported to petri dishes 15 cm in diameter. Germinated seeds were counted daily to calculate germination percentage, rate and uniformity. In addition, time trends of water absorption in different treatments were investigated. Combined analysis of variance results indicated that the population (location) has no significant effect, and prechilling and scarification treatments and their interactions have significant effects on germination components. According to results, the most effective treatments in non-prechilling and 2 weeks prechilling were soaking in boiling water for 5 and 10 seconds followed by soaking in sulfuric acid for 20 minutes, respectively. Based on obtained results, in prechilling for 3 months none of the chemical and mechanical treatments have acceptable germination. Germination percentages were 52, 50.5 and 53 percentages (in non-prechilled seeds) and 58, 63.25 and 63.5% (in 2 weeks prechilled seeds) in soaking in acid for 20 minutes, and soaking in boiling water for 5 and 10 seconds treatments, respectively. In the prechilling for 3 months, germination percentages of these treatments decreased to 12, 19.25 and 19.2%.