JOURNAL OF AGROECOLOGY (کشاورزی بوم شناختی)
Year:2017 | Volume:7 | Issue:1 |Papers Count:13

Introduction: Conservative agriculture with minimal adverse effects on the environment has been the subject of great interest recently as a means of promoting sustainable crop production and food security (Nkala et al., 2011). The approach is practiced in large-scale commercial agriculture. Conservative agriculture also encourages the optimal utilization of resources such as soil and water and helps the sustainability of products in the agroecosystem (Stavi et al., 2016). Nonetheless, due to the diversity of conservation farming operations around the world, it is critical to prioritize different tillage methods according to cultivation conditions and climatic conditions (Miller et al., 2012). The main objective of this study was i) to assess the efficacy of different conservative soil tillage (minimum and/or zero tillage) in combination with crop residue and fertilizer management in achieving maximum crop production; and ii) to assess the effects of management practices on agroecosystem performance using agronomic and environmental data and scoring function descriptions.Materials and methods: To achieve the goals, a field experiment was carried out involving 7 treatments with varying combinations of different tillage methods, crop residues and fertilizer management on a field of maize which was planted after the cultivation of a wheat crop. At the end of the growing season, the chemical and physical soil properties as well as the total yield of corn were measured. The physical and chemical parameters measured in the soil included electrical conductivity, field capacity, available water, porosity, pH, soil organic carbon, total crop biomass and maize yield. Agroecosystem performance was assessed using a computer program entitled the AgroEcosystem Performance Assessment Tool (AEPAT). It utilizes performance-based index methodology to derive a relative ranking of agroecosystem performance among management practices for functions and indicators included in the procedure. Data measured by the software AEPAT are rated from 0-100 to calculate two agroecosystem functions including conservation agriculture and food production.Results and discussion: The results showed that “stalk chopper+disc+100 kg N-fertilizer+ditcher” treatment resulted in the maximum amounts for field capacity (25.63%), available water (15.63%), porosity (49.2%) and organic carbon (0.73%). The highest total biomass (87.3 th-1) and ear yield (23.8 tha-1) was also obtained using this treatment. In contrast, the lowest amounts for these parameters were obtained with the “stubble burning + disc + ditcher” treatment. This was due to the stubble burning which increased the soil electrical conductivity and reduced the physical and chemical soil quality. On the other hand, leaving the on-farm residue in place plays an important role in regulating electrical conductivity and soil salinity. It can be concluded that the type of agriculture practiced affects the soil physicochemical properties to a high extent. Leaving crop residue in the field may increase the soil biological activity resulting in soil porosity and aggregation. The analysis on sustainability of agricultural practices showed that “stalk chopper+disc+100 kg N-fertilizer+ditcher” treatment had the highest score for agroecosystem performance (61.21) in terms of both optimum yield and sustainability. The lowest score of 7.63 was obtained with “stubble burning+disc+ditcher” treatment.Conclusion: In conclusion, it was demonstrated that conservative tillage in combination with crop residue not only led to a higher maize yield but also improved the soil quality. Nonetheless, for conservative tillage to be effective adequate N-fertilizer, as a starter to provide needed crop growth nutrients, must be applied. In addition, the efficiency of the indexing score is critical in discriminating between different agricultural practices within and across agroecosystem functions. The agricultural practices had a direct effect on agroecosystem performance and the soil physicochemical properties can be used as an index to assess agroecosystem function and performance.

Introduction: Intercropping has many advantages including improved soil conditions (Chen et al., 2004), increased resources and better weed control (Banik et al., 2006). Due to their positive effect on forage quality, intercropping of cultures has an important role in farming systems. Furthermore, intercropping improves absorption of solar radiation, increases the activity of soil microorganisms and contributes to better weed- and pest-resistant conditions (Karadage, 2004). The goal of this research is to investigate intercropping of maize and sorghum with legumes, such as mung beans, cowpeas and clover, in order to evaluate the benefits. The benefits should include increased yield, improved quality forage (higher protein levels), and better weed control. Intercropping should best suit the climatic conditions of the region and improve agricultural practices.Materials and methods: In order to investigate the effect of additive intercropping of maize and sorghum with legumes on qualitative and quantitative forage and weed growth, a field experiment was carried out over two years, in the 2011-12 growing seasons in the village of Mafin-Abad, in the Eslamshahr region of Tehran Province. Maize and sorghum monoculture and their intercropping with three different legumes (mung beans, cowpeas and berseem clover) in different additive intercropping systems were compared in a randomized complete block design (RCBD) with three replications. The traits evaluated in this study include yield, forage dry matter, protein, index against ground, and economic advantages.Results and discussion: The results showed that intercropping increased forage dry matter and crude protein. Intercropping also significantly decreased weed dry weight. In all intercropping treatments, LER was above 1, indicating yield advantages for intercropping. Maize and cowpeas in the 100% density treatment showed the best results over both years and produced the highest dry forage yield, LER and CP and the least amount of weed dry weight. Based on the results of this experiment, it could be concluded that maize and sorghum-legume intercropping could substantially increase forage quality and quantity. These intercrops can be recommended to replace monoculture systems. Maize and sorghum-cowpea additive intercropping could be highly recommended because of higher forage quality and quantity with fewer side effects on the environment. Conclusion: The results showed that intercropping could be used to increase yield, improve forage quality and weed control. Intercropping cultures also indicated that LER was more than 1 and led to a higher economic profit in comparison with a monoculture. This can be a suggestion for farmers to use intercropping in this recommended form. In the intercropping of maize and sorghum and cowpea, particularly with a density of 100%, cowpea clearly manifests itself. Therefore, intercropping can be recommended to farmers as a way to boost performance, revenue, forage quality (protein) and control weeds.

Introduction: The widespread use of chemical fertilizers and their effects on agricultural products is an issue that is still being studied and discussed. An important subject for study is the replacing of biofertilizers and organic fertilizers with chemical fertilizers and the application of integrated fertilizers to increase soil fertility in sustainable agriculture and for livestock (Wu, et al., 2005). Integrated fertilizing systems are more reliable than conventional fertilizers in producing better quality and higher quantities of whole forage in arid environments with water stress or a water deficit irrigation system. (Jahanian, 2012). On the other hand, drought stress is the most important abiotic factor that limits growth and development of plants in arid and semi-arid areas. Water stress conditions can also effect the root’s ability to uptake nutrients and leads to decreased forage quality. Evaluating new methods of irrigation and deficit irrigation systems can reduce the adverse effect of drought stress (Keshavarz Afshar et al. 2012). Therefore, the study of different fertilizing systems along with irrigation regimes is the main goal of this research in order to improve forage quality and trigonelline content in fenugreek plants. Materials and methods: A field experiment using a split plot on a RCB design with three replications was conducted at the Research Farm of the College of Agriculture, University of Tehran, in Karaj, Iran during the 2012 growing season. Treatments consisted of three levels of irrigation protocols assigned to the main plots as follows: complete irrigation (providing 100%), moderate drought stress (providing 75%) and severe drought stress (providing 50% of weekly evaporation). Six levels of fertilizing systems assigned to the subplots consisted of: a control, chemical fertilizer, biological fertilizer (seeds inoculated by Pseudomonas and Azotobacter), and three different integrated fertilizers: bio+100% chemical, bio+75% chemical and bio+50% chemical.Results and discussion: By increasing the drought severity, the percentage of CP, WSC, NDF, ADF, ash and trigonelline concentrations increased while the percentage of DDM, mineral contents and trigonelline yield followed a decreasing trend. By increasing NDF and ADF, forage quality was reduced. This reduction also came with a decrease in DDM. Drought stress caused an increase in the trigonelline, while most of the growth parameters in the fenugreek plant decreased. The highest values for DDM, mineral contents and trigonelline yield were achieved with full irrigation treatment accompanied by integrated fertilizer (Bio75% and Bio50%). The highest percent of CP, WSC and trigonelline was measured in severe drought stress together with Bio100%. Conclusion: The results of this experiment indicated that the integrated fertilizers were more efficient than bioand chemical fertilizers. They could mitigate the adverse effect of drought stress and produced the highest forage quality and secondary metabolite. These characters along with less use of chemical fertilizers produced the highest yield in quality and quantity compared to the other fertilization systems. Under the conditions in Karaj, it seems that application of integrated fertilizers along with moderate deficit irrigation (providing 75% of weekly evaporation), due to less water consumption and less negative effect on yield and forage quality, can be suggested for a sustainable agricultural system in arid and semi-arid areas like Karaj, Iran. Fenugreek, due to its dual positive characteristics, can be suggested as a medicinal-forage crop for livestock.

Introduction: Allelopathy is how one plant, by producing chemical compounds, affects another plant, either in a harmful or beneficial way, directly or indirectly (Prati and Bossdorf, 2004). Allelopathic phenomena have existed since the distant past and there are estimates in connection with weed control using this material. Pigweed (Amaranthus retroflexus) is one of the most important weeds (McNaughton et al., 2005). This study aimed to control pigweed using allelopathic substances (alcohol and aqueous extracts) of five species of poisonous houseplants.Materials and methods: This experiment was conducted as a factorial in a completely randomized design at the Agricultural Faculty, Tarbiat Modarres University in 2014. Experimental factors included five poisonous houseplants (oleander (Nerium oleander), Dieffenbachia amoena, Caladium candidum, Lilium ledebouri and Chrysanthemum indicum) at three concentrations of 5%, 15% and 25% of aqueous and alcohol extract, as well as their control. To evaluate the allelopathic potential of different concentrations in the alcoholic and aqueous phases of five poisonous species, root and shoot length, maximum germination, germination rate, uniformity of germination, germination percentage, seedling length and vigor index were compared. A glasshouse study was conducted to evaluate the effect of the potential of allelopathic extractions on the growth and physiological parameters such as the fresh and dry weight of leaves, stems and inflorescence, and the leaf area of redroot pigweed.Results and discussion: Results showed that the longest roots and shoots, maximum germination, germination rate, germination uniformity, germination percentage, seedling length and vigor index were observed in the treatment without extract, while the different extract treatments caused a sharp decline in trait values. The highest leaf dry weight was observed in a foliar application of 5% aqueous extract of diphenhydramine. The highest dry weight of inflorescences was seen in an alcoholic extract treatment that was applied to the soil with 5% of the Lilium extract. The highest dry and fresh weight of stem was observed in caladium aqueous extract with 5% of the extract applied to the soil. The highest leaf area occurred with a foliar application of 5% caladium extract. The highest fresh weight of leaf and inflorescences was obtained in aqueous soil treatment of 5% oleander extract.  Previous studies showed that the effect of plants from the cabbage family on canola seed germination and seedling length are significant. The results showed that canola had maximum and cress minimum potential of inhibition.  However there was no significant difference in their effects on root growth (Rezaei-Nodehiet al., 2003). There were significant differences between ornamental plants in terms of germination percentage and seedling length.  Generally, the higher concentration of the extract decreased the traits values which can be increased by increasing the amount and toxicity of allelochemicals. Also, it can be deduced that allelochemicals may be selective. This point is emphasized in the topic of weed control. On the other hand, root growth in redroot pigweed was inhibited more than shoot growth. Compared to the aqueous extracts, alcoholic extracts were more effective in decreasing the values of traits in this experiment.Conclusion: The results of this research confirm the previous reports that the growth of the root was more sensitive than the shoot and all plant traits can be affected negatively by allelopathic substances and their growth reduced.

Introduction: The carob moth, Apomyelois ceratoniae, is the chief pest of the pomegranate. Its control is only plausible using ecological pest management. Population dynamics and, in particular, population regulation is of prime importance in ecology. Different factors, including indigenous (intraspecific competition) and exogenous (climate and other organisms), may affect population size; the effects can be dependent or independent of population density (Price, 1997). In general, insect populations can go through equilibrium dynamics or nonequilibrium dynamics. In addition, a population at equilibrium level can be stable, unstable or have neutral stability. Stability denotes a return to the previous equilibrium level after a perturbation. Neutral stability, however, is a shift of the equilibrium to a new level (Cappuccino and Price, 1995; Schowalter, 2012). In the present study, the stability of the population equilibrium of the carob moth was examined.Materials and methods: To examine the effects of perturbation and the stability of population equilibrium of carob moths, two different experiments were performed. The first experiment included three treatments (perturbation using density reduction, perturbation using density increase, and no perturbation or the control). In the second experiment, only two treatments (perturbation using density reduction and the control) were carried out. All treatments were replicated four times using a randomized complete block design. The growth season was divided equally into two periods, and the number of infested fruits in 30 randomly selected trees per plot (orchard) was recorded weekly for each period. Data were analyzed using log-linear models to determine whether the equilibrium was stable, or if there were any shifts in the equilibrium level.Results and discussion: The results showed that when there was no perturbation, the equilibrium was unchanged. It was the same for perturbation using density reduction in the first experiment, since the equilibrium showed stability. However, perturbation using density reduction in the second experiment shifted population equilibrium to a lower level. In addition, perturbation using density increase also caused a change in population equilibrium such that the mean infestation of the pre-perturbation period was significantly greater than that for the postperturbation period. Our findings indicate that creating a perturbation in the population of carob moths may significantly change the stability and population equilibrium as seen in the first experiment with perturbation using density increase. In this experiment, the equilibrium shifted to a higher level after a perturbation. Moreover, in the second experiment with perturbation using density reduction, the perturbation decreased population equilibrium, indicating a neutral stability. When there was no perturbation, carob moth populations showed persistence in a stable manner, where the same equilibrium was recorded for both time periods. It can be said that populations that were not subjected to a perturbation may persist if there are enough food resources. Therefore, these populations cannot be easily perturbed or made unstable by climate or natural enemies unless the populations are manipulated by human practices such as pest management strategies.Conclusion: It was concluded that by using a perturbation, carob moth populations can be ecologically managed. With exact times and applications of ecological strategies of pest management (such as perturbation), it is possible to benefit from the method by lowering population equilibrium to below the economic injury level. Thus, the lowered level of population equilibrium is very important due to its stability, preventing usage of extra pest management practices.

Introduction: Nitrogen is needed in plants to form chlorophyll as well as to increase crop protein and plant yield. Application of too much nitrogen-containing fertilizers, however, is not economical. It has the additional disadvantage that it ultimately ends up in groundwater resources. Potato production in light soils usually requires a high consumption of nitrogen and frequent irrigation. At the beginning of the growing season, potatoes need a lot of nitrogen. High consumption of it at the end of the growing season, however, will cause increased foliage instead of larger tubers. Studies with high levels of nitrogen input aimed at comparing fertilizer regimes have also shown differences in nitrogen use efficiency (NUE). In recent years, the use of nanotechnology has been considered. With respect to the food recommended in most cultures, and limited research on the efficacy of nanofertilizers on crops, the present study is meant to evaluate the effectiveness of two types of nitrogen nanofertilizers, sulfur-coated urea and urea fertilizer, on potato crops.Materials and methods: The effect of nitrogen fertilizers on nitrogen efficiency in potato cultivation were investigated by performing a factorial experiment based on a completely randomized design with four fertilizer treatments. These included applications of Nano-Nitrogen Chelate (NNC), Sulphur Coated Nano-Nitrogen Chelate (SNNC), Sulphur Coated Urea (SCU) and Urea (U) in the greenhouse over two years. Each treatment, including 46 kg-N/ha, 92 kg-N/ha, and 138 kg-N/ha, with three replications were compared. The study parameters included nitrogen efficiency indices, leaf nitrogen percentage, yield and tuber nitrate. Also calculated for each treatment were the N-efficiency parameters of Agronomic-Nitrogen Use Efficiency (A-NUE), Economic-Nitrogen Use Efficiency (E-NUE), Nitrogen Uptake Percentage (NUP), Agronomic-Physiologic Nitrogen Use Efficiency (APNUE) and Economic-Physiologic Nitrogen Use Efficiency (E-PNUE).Results and discussion: The results showed that the maximum nitrate concentration of 240 mg kg-1 in tubers was obtained using 138 kg-N ha-1 supplied from urea. The lowest nitrate concentrations came from the nanofertilizer and SCU treatments. In total fertilizer treatments with increased N application, the amount of A-NUE, E-NUE and NUP decreased in both years. The SNNC in the first year and SCU in the second year had the highest E-NUE and ANE of the fertilizer sources. Comparison of means indicated that the highest tuber nitrate in the first year (215.63 mg kg-1) and in the second year (239.7 mg kg-1) was the outcome of the 138 kg-N ha-1 U treatment. Also, the results showed that in the first year, the highest E-NUE was the product of the first nitrogen level of SCU while the lowest levels were produced by the third nitrogen level of urea. It may therefore be concluded that nanofertilizers and SCU are more efficient in cultivations with nitrogen requirements. The changes in the E-PNUE index are similar to those in the E-NUE index. In other words, the values of E-PNUE and E-NUE decrease with increasing fertilizer applications while that of the E-PNUE increases with increasing nitrogen. The potato experiments of Darwishet al. (2006) and Halitligil et al. (2002), showed that E-NUE and E-PNUE were reduced with increasing nitrogen levels of urea treatment. The A-NUE and A-PNUE did not affect yield equally. Also, the role of fertilizers with equal nitrogen in yield increase did not have the same function; nanotechnologies have a synergistic effect on plant response to nitrogen use.Conclusion: Since a higher yield with the least adverse environmental effects is paramount in the third millennium, it is essential to use suitable fertilizers. The application of nanotechnology to agriculture in recent years has attracted much attention. In this study, reduced nitrate leaching and increased potato yield with an emphasis on reduced soil and water pollution were investigated in experiments with treatments that consisted of three nitrogen levels of NNC, SNNC, SCU, and U. The results showed that the 138kg-N/ha SNNC and 138kg-N/ha NNC produced the highest tuber yield. The lowest yield was obtained from the application of 138kg-N/ha U fertilizer. Comparing N-efficiency parameters showed that the highest E-NUE value was obtained with the first nitrogen level of SCU and lowest was the outcome of the third nitrogen level of Urea. Moreover, comparison of different levels of nitrogen indicated that low nitrogen levels in slow-release fertilizers performed better than the high levels of U fertilizer, which indicates an economic advantage as well. Since this experiment was conducted under greenhouse conditions, repeating this research in field conditions and with other crops is recommended.

Introduction: Applying modern technology such as nanotechnology to agricultural sciences is essential.  Nanotechnology has many applications in enhancing the ability of plants to absorb nutrients (Mousavi and Rezaei, 2011). Cereals are highly important for their high dry matter production. They are, however, poor in protein content which shows their low quality and nutritive value. It is essential to use intercropping of cereals with legumes extensively to provide acceptable crop yield and quality (Ghanbariet al., 2007; Dahmarde, 2010). This study was conducted to evaluate the effects of spraying nano-iron chelate fertilizer on a pearl millet-cowpea intercropping.Materials and methods: This experiment was conducted as a split randomized complete block design with three replications in 2015, at the research field of the Agricultural and Natural Resources of Bampour, Sistan and Baluchestan provinces. In this experiment, pearl millet is considered a main crop. Nano-chelated iron was sprayed at concentrations of 0%, 1%, 2% and 3% in two stages comprising main-plots and 5 cropping systems including: pearl millet sole culture, cowpea sole culture, 100% millet+20% cowpea, 100% millet+40% cowpea and 100% millet+60% cowpea. Evaluated parameters included plant height, leaf number per plant, one-thousand grain weight, grain yield, biological yield, harvest index and Land Equivalent Ratio (LER).Results and discussion: Results indicated that the interaction of nano-iron chelate and cropping systems was significant on all studied traits (except leaf number of pearl millet and cowpea and LER). In addition, the effects of nano-iron chelate was significant on all studied traits, with the exception of pearl millet plant height. Mean comparison revealed that plants in a pearl millet sole culture that were sprayed with a nano-iron concentrate of 3% increased grain yield by 13 percent compared with non-sprayed plants of 100% millet+20% cowpea. Among fertilizer treatments, spraying with nano-iron at a concentration of 3% increased the grain yield of pearl millet by 46 percent in comparison with those not sprayed. Spraying a cowpea sole culture with nano-iron at a concentration of 3% increased yield by 11%, compared with unsprayed 100% millet+20% cowpea. In addition, spraying with nano-iron at a concentration of 3% increased cowpea grain yield by 43% over the unsprayed. The maximum LER (1.8) was obtained at 100% millet+60% cowpea.Conclusion: The results of the experiment confirmed that nano-iron chelate fertilizer was effective on intercroppings of pearl millet and cowpea. Plants sprayed with concentrations of 3% had the greatest morphological characteristics and yield of both crops. Low amounts of iron in the soil along with a nano-iron chelate treatment led to increased grain yield. Due to inter-plant completion, the greatest morphological characteristics of both plant species was obtained when sown in a sole culture.

Introduction: Removing the yield gap (the difference between farmed yield and potential yield) is known as the most important way to increase crop production (Egli and Hatfield, 2014). Therefore, the amount of yield gap and the reasons for it are important. Soybeans [Glycine max (L.) Merrill] are one of the most important oilseed crops in the world (FAOSTAT, 2016). In Iran, the area of soybean cultivation is up to 66,000 hectares and annual production is 151,000 tons (Ministry of Agriculture Jihad, 2013). This does not meet domestic requirements, however, so soybean production should be increased. For this purpose, a field study was conducted in 138 farms using an application of regression modeling in 2013-15 in cities of Gorgan and Aliabad Katul.Materials and methods: Farms were selected with the help of agricultural service centers. Based on information provided by the service centers, farms were selected based on their diversity in terms of area under cultivation, management and yield. Management factors included a history of production, planting methods, inoculated or noninoculated seed with bacteria, seed rate, nitrogen fertilizer (N) rate, phosphorus fertilizer (P2O5) rate, potash fertilizer rate, the number of plowings, planting date, cultivar type, previous crop, use or non-use of N fertilizer top-dressing, number of N fertilizer top-dressing, use or non-use of herbicides, use or non-use of pesticides, animal manure type, irrigation type and amount, harvest methods, and others (a total of 67 management factors). All information about management operations were recorded and measured. Then, the relationship between actual yield and the 67 management variables were assessed using stepwise regression.Results and discussion: The average yield for farms was 2,908 kg per hectare and the maximum yield was 5,100 kg per hectare. Model Root Mean Square Error (RMSE) was 274 kg per hectare and coefficient of variation (CV) was 9 percent. These statistics showed that the accuracy of the model was acceptable. Therefore, the model could be used to determine the yield gap and the share of yield constraints. Model yield, on average, was estimated at 2,918 kg per hectare and maximum yield was 4,820 kg per hectare. In this model, total yield gap has been estimated at 1,902 kg per hectare. Accordingly, the most important factors in yield gap for the region included: number of irrigations with 29% (equivalent to 535 kg per hectare), net nitrogen with 22% (equivalent to 419 kg per hectare), P2O5 with 20% (equivalent to 365 kg per hectare), planting date with 16% (equivalent to 302 kg per hectare) and disk number with 13% (equivalent to 250 kg per hectare).Conclusion: With optimized items listed, soybean yield could be increased approximately 1,871 kg per hectare in Gorgan and Aliabad Katul. Use of this method isn’t suitable for determining optimum values. In order to determine optimum values for each listed item, other methods can be used for yield gap analysis, such as a boundary line analysis.

Introduction: Common bacterial bean blight with the casual agent of Xanthomonas axonopodis pv. phaseoli (Xap) causes severe damage to the crop in the west of the country. The disease is prevalent in areas with warm weather, causing up to 80% yield reduction (Lak and Dorri, 2009). One of the ways to control the plant disease is to use bacterial biological agents such as Pseudomonas fluorescens and Bacillus subtillis. The aim of this study is to investigate the biological agents that control common bacterial bean blight disease.Materials and methods: First, the growth inhibitory effect of bacterial biocontrol agents against Xap was investigated in vitro on the Nutrient Agar (NA) medium for 24 hours. Then the effect of biological agents (P. fluorescens, B. subtilis, and the combination of them) against Xanthomonas axonopodis pv. phaseoli were evaluated in a completely randomized design in addition to four replications under greenhouse conditions. After about three weeks, indices such as fresh root and shoot weight, dry root and shoot weight, root and stem height, plant resistance, and the percentage of plant disease (according to the coding system ICTA and the method of Webster et al., 1983) were measured and used to analyse the control power of the biological agents.Results and Discussion: The results showed the biological agents prevented the growth of Xanthomonas axonopodis pv. phaseoli by creating a zone inhibitor in the NA medium. The diameter of zone inhibition for P. fluorescens and B. subtilis were respectively 32.75 and 20.75 mm. Zone inhibition indicated that the biological agents P. fluorescens and B. subtilis reduced by 20% and 30% Xanthomonas axonopodis pv. Phaseoli’s growth in the culture medium. The severity of Xanthomonas axonopodis pv. phaseoli symptoms on bean plants under greenhouse conditions were more than 63%, but the biological treatments reduced the symptoms and increased the plant’s strength. In this study, the combination of these two biological factors’ treatment )P. fluorescens + B. subtillis) had the greatest biocontrol effects on the disease and reduced bean common bacterial blight symptoms up to 51% compared to the control. They converted the plant from susceptible to moderately resistant. Singular treatments of P. fluorescens and B. subtilis reduced symptoms up to 21.74% and 15.22% respectively. These changes in the weight and height of the plants infected by the biological agents Xanthomonas axonopodis pv. phaseoli had a significant effect on the one-percent significance level. It has been found that these biological agents can prevent the growth of plant pathogenic bacteria such as Xanthomonas axonopodis pv. phaseoli by the production of antibiotics, secondary metabolite (Raijmakers and Mazzola, 2012), direct impact on plant growth, production of auxin and cytokinin, and stimulation of plant resistance (Nejad et al., 2000; Kilian et al., 2000). Conclusion: These biological agents, such as P. fluorescens and B. subtilis, had a significant impact in preventing the growth of Xanthomonas axonopodis pv. phaseoli. Thus, we could use these biological agents and their materials production to control common bean blight disease.

Introduction: Today, the use of cover crops by farmers has its own economical approval with the benefit of reducing herbicide application through improved soil conditions and crop yield. Among the various plants, rye is the most suitable for use as a cover plant due to its high biomass production and allelopathic compounds.Materials and methods: In order to the evaluate the effects of different levels of rye densities and planting dates on the density and biomass of weeds in a forage maize field, a factorial experiment was conducted with a randomized complete block design with three replications at the agricultural research station in Ardabil. The first factor was the rye planting date at an interval of 15 days: (25 April, 10 May, 25 May and 10 June). The second factor was the rye planting densities that included (0 kg, 80 kg, 120 kg, and 160 kg per ha). To investigate the effect of rye on density and weed biomass, a weed sampling was conducted in two stages. The first stage was done at 8 leaves of maize and the second was done a week before tasselling of maize on the basis of 0.5 by 0.5 meters. Also measured were ear weight, length, and diameter, and shoot fresh weight, stem diameter, and fresh forage yield of maize.Results and discussion: The results showed that the density and biomass of annual and perennial weeds were influenced by the main and interactive effects of the rye planting by date × plant density. Due to their allelopathic features, cover crops can control weed growth, bring about higher growth rates and rooting power, as well as help preserve the earth with suitable covering at early planting dates (Tobehet al., 1999). In an experiment with soybeans, rye as a cover crop reduced weed biomass 60% to 90% due to its allelopathic effect (Ateh and Doll, 1996). In general, the first planting date of rye (one month prior to the planting of corn) had the greatest effect on reducing the density and dry weight of weeds. The first planting date by the third density, reduced the density of the annual weeds by 89% and its dry weight by 93%. Perennial weeds were reduced by 83 percent and their dry weight by 92 percent. In spring planting, because of a lack of rye vernalization, there would be no troublesome new weeds, because the plant cannot reproduce by itself within a few months in most areas. This disappearance of rye adds to the appropriate control of weeds. Weed control by rye leads to enhanced competitiveness of maize and increases forage yield, cob fresh weight, length, diameter, stem fresh weight, and the diameter of maize. The main effect of the density with the highest density of rye (third density), is that it is more likely to be competitive with maize, reducing the availability of nitrogen, the release of allelopathic materials and soil cooling. This resulted in significant reduction in maize yield components. The combination of the optimum planting date (third planting date) along with greater weed control, resulted in a significant increase in maize yield. Reduction of cover crops residue, especially small grains, is related to reduced nitrogen availability, reduced toxins and lower soil temperatures (Westgateet al., 2005; Norsworthy, 2004).Conclusion: Together with the optimum planting dates and density, the use of cover crops, especially rye, is generally a good choice to control weeds in corn fields.

Introduction: To design effective weed population control measures, the identification, characterization, and quantification of weed species within a certain area are important steps to form the basis for weed management (Kropff and Spitters 1991). Information on weed density, distribution, and species composition might also help to predict crop yield losses due to weeds and can help determine whether it is economical to control a specific weed problem. The population and seed bank of weeds is very dynamic. The population dynamics of these plants depends on climate and soil factors and farm management practices (Firehun and Tamado, 2006; Kumaraet al. 2007; Derksen et al.2002). Thus, the objectives of this study were to determine the composition and the soil seed bank of weeds in soybean fields in Kalaleh, Golestan Province, and to assess the influence of soil types and major agronomic practices on weed species and the soil seed bank.Materials and methods: This study was performed to assess the influence of crop management practices and soil characteristics on density and composition of weed seedling and the soil seed bank of soybean fields in Kalaleh, Golestan Province, in 2014. Data on crop management practices (rotation, manure and chemical fertilizer used, field area, kinds of herbicide and seeds) and soil characteristics (pH, EC and organic matter) were collected from 200 soybean fields. Samplings of weed populations (seedlings) and the seed bank were carried out at the beginning of soybean growth (before implementing the control) with W method in 50 cm ×50 cm quadrates at 0-10 cm and 10-20 cm depths. Finally, the effects of soil and agronomic practices were investigated on dominant weeds using a multi-variate analysis.Results and discussion: The survey of weed flora in Kalaleh soybean farms showed 16 plant species (belonging to 13 plant families) had infected the farms. The major observed species wereCyperus sp (70.60%), Sorghum halepenseL. (45.42%), Ipomoea spp. (37.19%), Cucumis melo (30.33%), and Cleome viscos a L. (27.29%). Seeds of 19 species were observed in depths of 0-10 cm. and 20 species were observed in depths of 10-20 cm. The major species observed in both depths wereAmaranthus sp., Portulaca oleraceae L., and Cleomea viscosa L. The results of the multi-variate analysis indicated that the effect of crop management and soil factors had different effects on seedlings and the soil seed bank of weeds. Generally, crop management practices had a greater effect than soil characteristics. In this study, herbicides (seedling and seed bank), manure (seed bank) and pH (seedlings) were the major factors that affected weed population and the seed bank.Conclusion: According to the dominance of five species including Cyperus sp., Sorghum halopense, Ipomoea sp., Cucumis meloand Cleome viscosa in weed flora and the seeds of three species, Amaranthus sp., Portulaca oleraceaeand Cleome viscosa in the soil seed bank, it can be said that the above species contribute significantly to the reduction of soybean yields in this region. The results showed thatfarmers’ management practices have a greater impact on the weed population and the seed bank than soil factors do.

Introduction: Nowadays, regarding better integrated weed management and its control, attention to weed biology is critical and should be accepted as a scientific activity in weed science society (Rashed Mohassel et al., 2001). Precise weed biology identification will lead to better management practices (Alebrahim et al., 2009; Pahlevani et al., 2007). To be successful, weed management programs based on weed ecology and biology, need to acquire the correct information about environmental factors such as temperature, humidity, and their effects on plant characteristics (Zand et al., 2007). In weed science, non-chemical weed management by physical methods is one of the best usable methods. The purpose of this study was to evaluate Gladiolus weed biology to develop techniques for sustainable management.Materials and methods: This research was done in the Faculty of Agriculture and Natural Resources laboratories at the University of Mohaghegh Ardabili. Treatments included: 1- Evaluating the effect of different temperatures (5, 10, 15, 20, 25, 30, 35 and 40 degrees centigrade) on the emergence of Gladiolus corms in a completely randomized design with 4 replications. 2- Evaluating the effect of different temperatures and drying periods on the emergence of wild Gladiolus corms as a factorial in a completely randomized design with 4 replications. The first factor was storage periods in an oven for 4 different periods (1, 2, 3 and 4 weeks). The second factor was oven temperature at 5 levels (20, 23, 25, 35 and 40 degrees centigrade). 3- Evaluating the effects of different temperatures and freezing periods on the emergence of wild Gladiolus corms as a factorial in a completely randomized design with 4 replications. The first factor was storage periods in an incubator for 4 different periods (1, 2, 3 and 4 weeks) and the second factor was freezing temperatures at 6 levels (0, -5, -10, -15, -20 and -25 degrees centigrade).Results and discussion: Results showed that among different temperature treatments, the corms emerged at 15- 30oC. The higher emergence percentage was 87.5% at 20oC. By increasing water reduction in corms in the oven, emergence ability was reduced. Further, with a 36.25 percent water reduction in corms, emergence ability reached zero. Corm emergence ability was affected by temperature and oven storage length. The highest survival rates with 100% emergence was with a temperature between 20 -25oC after being stored for 1-2 weeks in the oven. Results also showed that by increasing the freezing period and lowering the temperature, the survival of wild Gladiolus corms was reduced. Further, at temperatures of -15, -20 and -25oC the emergence ability reached zero. The highest emergence rate was at 0oC with a 1 week freezing period.Conclusion: In this experiment 20ºC, was the optimum temperature for emergence of corms. Generally, by putting corms in temperatures higher than 30ºC or lower than -10ºC, the emergence ability reached zero. Thus with no chemical treatment and just by using environmental conditions in cold and warm climates, this weed density will be reduced and sustainable management will be achieved.

Introduction: Analysis of the structure of the global market and identifying the comparative advantages is one of the most important measures to promote exports and investment in export production (Li and Bender, 2002). The focus of this study is the structure and development of the pistachio trade market with an emphasis on the role of Iran in recent years. For this purpose, basic indices of market structure have been introduced and calculated. Materials and metods: The structure of the world pistachio export market has been investigated to determine the degree of the concentration of exporters and importers based on market concentration indices (e.g. the reverse of the number of active firms doing pistachio import/export), concentration ratio of pistachio import/export firms, Herfindahl-Hirschman Index, and Hannah-Kay index (Hannah and Kay, 1977). Changes in these indicators over time have been analyzed as a measure of the structural changes in the global market. The role that Iran can and should take in these developments has also been determined based on the revealed comparative advantage (RCA) and symmetric RCA (Mehrabi Boshrabadi and Neshat, 2009).Results and discussions: For many years )before 2008(, Iran was the world’s top pistachio exporter with more than half of all exports coming from Iran. During 2008-2013, however, that share has diminished. From 37% in 2008, pistachio exports dropped to 17% in 2013. This decline reflects the advancement of competitor countries, especially the USA, in world markets. The results showed a strong monopoly in the market structure of pistachios with four dominant firms from Iran, America, China and Turkey in the period under review. Iran’s comparative advantage is very high compared to others, but the downward trend during this period indicates the absence of a specific export strategy.Conclusion: Internal and external barriers against the export of Iranian pistachios, along with opportunistic countries such as America and Turkey that have implemented long-term plans to increase market share, have caused severe fluctuations in Iranian pistachio exports in recent years. Having long-term programs to promote exports on the agenda along with active and flexible business policies could lead to better comparative advantages in agriculture. Controlling and stabilizing the exchange rate policy could also affect the stability of exports and therefore the export comparative advantage. Clear information on future trends in exchange rates will have an important role in maintaining Iran's position in global markets.