مجله کشاورزی بوم شناختی
سال ششم شماره 2 (1395)

Corn is one of the important forage plants for livestock. Yield improvement and forage quality are essential issues in forage production. Bio-fertilizers and soil amendments have great potential as suitable alternatives for chemical fertilizers, but are less known in this area. The combined application of zeolite and mycorrhiza can improve conditions for plant growth while preventing loss of nutrients from the rhizosphere. The researchers reported that the combined use of zeolites (5 percent of soil weight) and mycorrhizae reduced leaching of nitrogen and phosphorus (Molaee et al., 2010). This experiment was performed to study the influence on corn growth of zeolite as a soil mineral amendment and mycorrhiza, at different levels of phosphorus chemical fertilizer and concentration of grain elements.
The experiment was performed as factorial study based on the complete randomized block design with three replications at the Faculty of Agriculture of Shahrood University located in Bastam in 2013. The experiment factors included zeolites, at two levels, 0 and 9 tons per hectare and mycorrhiza species (Rhizophagus irregularis), at two levels, Inoculation and without inoculation and triple superphosphate chemical fertilizer at three levels, 0, 50 and 100 kg per hectare which were applied to corn single cross 704. Determination of plant root colonization was carried out based on the Giovannetti and Mosse method (Giovannetti and Mosse, 1980). Measurement of the amount of chlorophyll was carried out at the flowering stage (tassel ratings) using a chlorophyll meter (SPAD 502). For measuring the nutrients of grain digestion, the perchloric acid and nitric acid method was used at a ratio of 1 to 6 (Hanson, 1950). Phosphorus was measured with a spectrophotometer (Hanson, 1950), potassium with flame photometer (Ghazzanshahi, 1997) and calcium grain using titration (Ghazzanshahi, 1997).
The results showed mycorrhizal fungi inoculation with root corn resulted in an increased percentage of colonization of about 25%. The application of phosphorus fertilizer (p≤ 0.01), zeolite (p The results showed application of mycorrhiza with soil amendments (zeolite) can be an alternative to some parts of phosphate chemical fertilizers in sustainable agricultural systems for the cultivation of maize and can improve the quality of the grain. Since the plant variety was a forage plant, and given the importance of forage quality in animal nutrition, the application of biological fertilizers and soil amendments can prevent the excessive consumption of chemical inputs while achieving a favourable biological yield and improving forage quality on farms.

Despite the harsh and fragile ecological conditions in saline regions (Jafarian et al., 2009), There are plants that can tolerate these conditions and, for the production of food, pharmaceutical and forage in saline lands are suitable (Abbaszadeh, 2011). Must with the discovery of aspects and potential benefits in the salinity lands, we must move towards environmentally sustainable use and, in this regard, medicinal and grassland plants such as Artemisia sieberi can be among the suitable plants in this case.
In order to evaluate the germination characteristics of Artemisia sieberiBesser., seeds were collected from Ghom, Karaj and Tehran and an experiment was conducted in the laboratory of the Research Institute of Forests and Rangelands, Tehran, Iran, during 2011. The experiment was done as factorial layout based on a randomized complete block design with three replications. Treatments included three populations (such as Ghom, Karaj and Tehran), three temperatures (including 10, 25 and 30oC) and four salinity stress levels (such as 0, 100, 200 and 300 mM, induced by NaCl). Characteristics measured included germination percentage, germination speed, plumule length, radicle length, ratio of radicle length/ plumule length and Longley seed vigour index.
Results of mean comparison of population × temperature indicated that the highest germination percentage was achieved in Ghom × 10oC and (35.58%) the maximum plumule length was observed in Tehran × 10oC (1.23 cm). In the interaction of population × salinity, the highest germination percentage was achieved in Tehran × 0 mM (68.66%) and the maximum plumule length was achieved in Ghom × 0 mM (3.52 cm). In the interaction of temperature × salinity, the highest germination percentage was achieved at 25oC × 0 mM (60.55%) and the highest plumule length was achieved at 30oC × 0 mM (2.48 cm).
The results showed that different populations of sagebrush (Artemisia sieberiBesser) had different responses to different levels of salinity and temperatures. The main cause of these differences could be due to the effect of habitat on the mother plants in the years, habitat soil conditions, habitat climate conditions in the seed collection and filling stages and the maturity of the seeds. Due to differences between the populations used in the study, more than 10 % germination and climate variability Iran, it seems that investigation of more populations can, in addition to identifying those tolerant to salinity, identify plants with different qualities suited for medicinal uses and rangelands. Generally, the suitable temperature was 25 ° C and, despite salinity tolerance by Artemisia sieberi Besser, the highest percentage of germination occurred under non-stress conditions. These results indicated that Artemisia sieberiBesser is not an obligata Halophyte plant. It also concluded that the effect of temperature and salinity combined and, so it seems, the management of salt-affected land cultivation in addition to plants’ resistance to salinity, of tolerant plants with a relatively short growing season or cold tolerant plants can be exploited. It was found that plant in the cooler weather conditions at the beginning and end of growing seasons (spring and autumn), plants could easily finish their life cycle. According to the extended natural habitat of Artemisia sieberiBesser in different habitats of the country and the medicinal and grasslands value of this plant we could assert that, as a result of this research, Artemisia sieberi Besser is one of the plants with a high potential , and a that it merits applied research and complete studies to recommend this species.

Energy use efficiency in agricultural systems needs to be improved to reduce dependency on nonrenewable energy sources (Erdal et al., 2007). Recognition of crop production methods that maximize energy efficiency and minimize application of energy inputs is essential (Ozkan et al., 2004b). The objectives of this study were to compare melon and cotton production systems in terms of energy use efficiency, energy intensiveness, energy productivity, benefit-to-cost ratio, renewable and non-renewable energy consumption in Torbat-e-Jam city in Khorasan-Razavi province.
Data were collected by using a face-to-face questionnaire from 104 and 75 melon and cotton farms, respectively, during 2011. Energy inputs included chemical fertilizers, diesel fuel, pesticides, seed, machinery and human labour (Ozkan et al., 2004a). Energy indices (energy use efficiency, energy productivity, specific energy and net energy) were computed for melon and cotton production systems. All inputs consumed in crop production were classified into direct and indirect, renewable and non-renewable sources. Input-output analysis was also used to determine economic criteria including gross return, gross value of production, net return, total cost of production, benefit-to-cost ratio and productivity.
The results revealed that energy consumed in melon and cotton production was 135382.5 and 98494.5 MJ ha−1, respectively. Among the energy inputs, electricity (45.4% and 59.0%, respectively for melon and cotton), irrigation water and chemical fertilizers contained the highest energy shares for melon and cotton farms in the region. About 71% of the total energy inputs used in melon production system was indirect and 29% was direct; while the share of direct and indirect energy for cotton production was 79%and 21% respectively. Results further indicated that 80% and 82% of total energy input for melon and cotton, respectively, was in non renewable energy, and only 20% and 18% was in renewable. Mean melon (fresh weight) and cotton (boll) yield was about 15767 and 3579 kg ha-1, and energy use efficiency was 0.22 and 0.44, respectively. Economic analysis indicated that total cost of melon and cotton production was 2468 and 1681 US Dollars per ha-1, respectively. The benefit to cost ratios were calculated as 1.63 and 0.57 in melon production system and 3.19 and 0.20 in cotton production system.
Low energy productivity in melon and cotton production systems indicated an intensive use of inputs not accompanied by increase in the final product. Consideration should be given to employing new electrical pumps to water pumping, increasing water use efficiency, introducing and implementing reduced (conservation) tillage and decreasing consumption of diesel fuel in order to decrease the amount of non renewable energy use in the region studied. This will lead to lower levels of water and soil pollution and will make the crop production environment friendly.

Worldwide interest in potato as a valuable crop for food security is increasing (Camire et al., 2009) and nitrogen (N) nutrition is the main factor determining growth and final yield of potato crops (Bangemann et al., 2014). Nitrogen deficiency limits crop growth, whereas nitrogen excess is often leached into the environment and results in pollution (Hu et al., 2014). Farmyard manure is another source of nitrogen and other nutrients which can decrease the demand for chemical fertilizers. The goal of this study was to investigate effects of using chemical fertilizers and farmyard manure on vegetative growth and tuber yield of potato in order to produce healthy potato crops and efficient utilization of chemical fertilizers and farmyard manure.
A field experiment was conducted in a randomized complete block design with three replications in the Ardabil area in 2013. The experimental treatments included: a control treatment; application of 326 Kg ha-1, 652 kg ha-1 and 978 kg ha-1 of chemical urea fertilizer; application of 21.1 ton ha-1, 42.3 ton ha-1 and 63.5 ton ha-1 of sheep manure; and application of 27.6 ton ha-1, 55.2 ton ha-1 and 82.9 ton ha-1 of cow manure. The fertilizing was done based on the application of 150, 300 and 450 Kg of nitrogen per hectare, respectively. During the growth season, date of emergence, flowering, tuber formation, and at harvesting time, the number of stems per plant, plant height, shoot dry weight and, finally, yield and yield components were measured.
According to the results, yield, yield components and phenological and morphological traits were all significantly influenced by the fertilizer treatments. Increased urea and farmyard manure application delayed full flowering and maturity compared with the unfertilized treatment. The application of cow manure (82.9 ton ha-1) and chemical fertilizer (978 kg ha-1) increased the duration of maturity by about 6.67 and 6.25 percent in comparison to the control, respectively, while emergence was accelerated by increasing farmyard manure. The effect of treatments on the number of stems per plant was significant (P : In general, manures were remarkably superior to chemical fertilizer with respect to growth and yield of potato; the highest yield, weight as well as number of tubers were produced under treatment with 42.3 ton ha-1 and 63.5 ton ha-1 of sheep manure. Hence, this treatment could be considered instead of continuous use of chemical fertilizers as a shift towards sustainable agriculture and to reduce pollution from chemical fertilizers.

Wheat (Triticum aestivum L.) is grown over a large area worldwide while wild oat (Avena ludoviciana) is one of the most important harmful weeds throughout wheat fields (Hassan et al., 2005). Reduction of wheat yield in competition with wild oat is related to weed density (Wilson et al., 1995; Cobb and Kirkwood, 2000) and elevated CO2 concentration caused change in crop-weed competition. Because of the importance of wheat for human food and the significant reduction in grain yield of wheat under competition with wild oat, this experiment was conducted to study the effects of atmospheric CO2 enrichment on some morphological characteristics, mineral nutrients and grain yield of wheat under weed competitive pressure from wild oat.
The experiment was laid out as split plot in a randomized complete block design with three replications, at the Agriculture Research Station, Faculty of Agriculture, Tarbiat Modares Universit, Tehran, Iran during the 2012-2013 growing season. Three CO2 concentrations, 400, 700 and 1000 ppm, and five weed densities, 0, 25, 50, 75 and 100 wild oat plants m-2 were allocated to main plots and sub plots, respectively. In this study, to avoid experimental errors, forty five open top chambers were established in the centre of each plot.
Results indicated that increasing the concentration of carbon dioxide caused an increase in height of wheat while increased wild oat density caused a decrease in the height of wheat. Concentrations of 400, 700 and 1000 ppm under density of 100 wild oat plants per square metre compared to the weed free control resulted in a 10.27%, 31.02% and 39.35% reduction in wheat height, respectively. Based on these results, the treatment of 100 plants per square metre of wild oat compared to control caused a decrease in spike length (48.8%) and grain yield (81%). In addition, generally increasing carbon dioxide and weed density caused increases and decreases in the N, P, K, Fe, Cu and Zn concentrations of wheat, respectively. Wheat yield decreases intensely up until 50 wild oat plants per square metre but, after this point, density decreases slowly. Based on the results shown, wheat yield decreased exponentially when wild oat populations varied from 0 to 100 plants m-2 and the loss approached 78% at 100 plants wild oats m-2.
Our work here indicates that increasing the concentration of CO2 caused increases in plant height, spike length and grain yield of wheat. Also, increasing wild oat density has an adverse effect on these characteristics and, so, caused a significant decrease in the grain yield of wheat.

Climate change and its diversity is one of the greatest challenges which will face humanity in this and future centuries and the economic effects of climate change on agriculture have been a concern for policymakers. The effect of climate change on the agricultural sector has been largely harmful: For example, the effects of periodic droughts and floods have always threatened the life of rural populations that depend on agriculture (Ranganathan et al., 2010). According to FAO (2014), an important part of the maize supply in Iran is provided through importation and one of the main reasons for the increase in maize imports over recent years is a decrease in its yield that depends on climatic conditions. Through improvement of domestic production essential steps can be taken towards self-sufficiency in production of this product (Kazemnejad and Gilanpour, 2014). Given that maize is one of the basic agricultural products and considering its importance and strategic role, a survey of the factors affecting production of this product and, in particular, the effect of climatic factors is necessary. So, in this paper the alignment of regional management of maize production and climate change was studied using a spatial model and panel data for 15 provinces during the period 1984-2010.
Material and In this research, a spatial econometric approach was used to study the effect of climatic factors on maize production and, due to the type of available data, a panel data approach has been used. Panel data provides a suitable environment for the development of estimation methods and researchers were able to use cross sectional and time series data to discuss issues that it is not possible to study through time series or cross section data alone (Baltagi, 2005). Climatic variables used in this study included the planting temperature, growth temperature, harvest temperature, planting precipitation and growth precipitation of product.
Results of the Moran test for presence of spatial effects in the panel data showed that there is spatial autocorrelation in the data and the spatial autocorrelation coefficient between the provinces is 0.47. This shows that, in order to survey effect of climatic factors on maize production, we need to consider the geographical situation and vicinity in the model. Estimation of the random effect spatial model (derived from a modified Hausman test) in surveying the impact of climate change on maize production showed that the increase in planting temperature has a negative effect on maize production while the square of planting temperature has positive effect on maize production. Also, harvest temperature has a positive effect on maize production and the square of harvest temperature has negative effect on maize production. Planting precipitation has negative effect and growth temperature has positive effect on maize production; also, the effect of the area under cultivation is positive.
According to the findings, it is advisable to avoid delaying maize planting in warm places such as Khozestan, Isfahan, Ilam, Yazd, Hormozgan and Semnan or, if it is possible, to use heat resistant maize seeds. In areas where the maize harvest is grown in winter, accelerating the harvest under warmer conditions leads to an increase in production. Moreover, it is better to plant maize in Kurdistan and Ghazvin provinces with little delay which is not affected by extreme rainfall of early spring. In Kurdistan, Lorestan and Ilam provinces that have high growth precipitation, it's better for farmers to be insured against systemic risk.

Over the past few decades, advances in technology have led to the increased use of energy and emissions of greenhouse gases. In this regard, researching the economic dimension of greenhouse gas emissions and their environmental effects, particularly in the present condition that their volume is increasing, has gained a lot of attention. This is due to the fact that the industrialization of modern societies has led to the use of fossil fuels such as coal, oil, and gas in production and services. Combustion of fossil fuels causes an increase in greenhouse gas emissions into the atmosphere of which carbon dioxide (CO2) is one of the most important. About 60% of greenhouse gas emissions in Iran is caused by the agricultural sector (Energy Balance, 2012) which is regarded as one of the main sources of such emissions. In the process of the production of agricultural products, greenhouse gases will be emitted as a result of inappropriate application of land and fertilizer, livestock, and the use of fossil energy (Behboodi et al., 2010) .So, in this study, the relationship between technological progress (land under modern irrigation and agricultural machinery), energy price and carbon dioxide emissions in Iranʼ s agricultural sector has been investigated.
For this purpose, a vector autoregressive model (VAR) and time series data during the period 1970-2012 were used .The reason for this choice of model, namely VAR, in this study is that it determines the long-running relationship between the variables and also has the ability to explain the short-run relationship between them. At first, the stationary degree of the variables was examined (Abrishami, 1996).
The results showed that, although not all variables are stationary at all levels, their first order differencing was stationary. After ensuring there is a convergence between variables, the results of model estimation are presented in two categories: the long-run relationship and the short-run relationship. The results showed that the energy price variable with a lag has a negative effect on CO2 emissions in the agricultural sector. With an increase in the energy price in agricultural sector energy demand, energy consumption will be reduced which leads, in turn, to reduced CO2 emissions. The machinery variable with a lag has a positive effect on carbon dioxide emissions in the agricultural sector. By assuming the same technology, increasing the number of such machinery results in more energy being consumed; increasing energy consumption leads to increased emissions of CO2. The land under modern irrigation variable with a lag has a negative effect on carbon dioxide emissions in the agricultural sector, with the short-run results confirming the long-run results. Share variables in the prediction error variance decomposition of carbon dioxide in the agricultural sector were also examined using the analysis of variance decomposition for a 10-year period. Results showed that energy price and land under modern irrigation have the most and the least effect on this variable both in the short- and long-run.
Therefore, one method to reduce carbon dioxide emissions without reducing of production is to improve energy intensity in the agricultural sector. If energy efficiency increases, it can reduce carbon dioxide emissions in this sector without reducing of production. Also, by employing multi-purpose machines it is possible to use less machinery and thus less use of energy. Modern technologies such as pressurized irrigation that reduce energy consumption and CO2 emissions are therefore recommended.

In recent decades, a new agricultural system known as ‘conservation agriculture’ was introduced to the world as a progressive solution for such challenges as soil erosion, environmental problems and the low input efficiency of energy, water and fertilizer that the conventional agriculture system is exposed to (Rolf Derpsch and Friedrich, 2009; Cavalaris and Gemtos, 2002; Romaneckas et al., 2009). In Iran, comprehensive studies covering all principles of conservation agriculture system have not been conducted. This research was undertaken in order to study the adaptation of the conservation agriculture system to the agricultural conditions of cold regions of Khorasan-Razavi Province and its effects on different crop yields to identify whether reducing tillage practice and preserving crop residue positively affect crop yield.
In order to study the effects of tillage method and residue amount on crop yield, an experiment with a split plot layout based on a randomized complete block design (RCBD) with three replications was conducted at the Jolg-e-Rokh Station of Khorasan-Razavi Agricultural and Natural Resources Research and Education Centre (59°E and 35°, 50´N) during two growing seasons (2013-2014). In this experiment, tillage methods were applied in main plots at three levels, namely (1) conventional tillage (mouldboard plough 2 times disc levelling planting with seeder), (2) minimum tillage (2 times chisel packer planting with seeder) and (3) no tillage (direct planting with a notill seeder). The residue amount was in a sub plot at 3 levels, namely no residue, 2- 30% residue and 3-60% residue of the previous crop.
Results showed that in Bersim clover, change in the tillage system reduced (P It seems that the use of a no-tillage instead of a conventional tillage method, especially when preserving residue, can obtain the same or higher yield in clover and sugar beet.

One solution for decreasing the environmental problems of urea in sustainable agriculture is slowing the release of urea via coating with plant metabolites. Plant phenolic compounds are natural urease and nitrification inhibitors, which can directly affect the composition and activity of enzymes and decomposer communities, thus influencing the rates of decomposition and nutrient cycling. Kiran and Patra (2003) and Mohanty et al. (2008) have reported that natural materials such as menta plant materials and neem seed kernel powder containing phenolic compounds, can act as urease and nitrification inhibitors. In addition, polyphenols can alter N availability by forming complexes with proteins (Hättenschwiler and Vitousek, 2000).
For this study, urea was coated with pomegranate fruit powder and its effect on nitrogen uptake, growth and grain yield of maize (single cross var.) was studied in a factorial experiment as a randomized complete block design with three replications. The experiment was conducted in 2013 at the Faculty of New Sciences and Technologies, University of Tehran as a pot and incubation experiment. The treatments were two levels of nitrogen fertilizer (from a urea source) include 100 and 200 mg kg of soil (65 and 130 kg ha-1) and four levels of pomegranate fruit powder including 0, 35, 70 and 100% w/w of urea. Urea was coated with pomegranate fruit powder using common methods and was applied. After maturity, the crops were harvested and traits such as grain yield, stem weight, leaf weight, root weight, biomass and N uptake were measured.
The results showed that the use of coated urea, particularly at the amount of 100% w/w, inhibited nitrification to the level of 15% and 23%, respectively, at 21 and 35 days after incubation and released it at 65 days after incubation. This lead to a significant increase in grain yield and total biomass at the amount of 13.3 and 173 g plant-1, respectively. Total nitrogen uptake also increased 23% with coated urea (in 100% w/w) compared to urea alone.
The results indicated that applying the urea coated with pomegranate fruit powder (PFP) rich in polyphenol, especially at a 100% concentration rate w/w urea, significantly increased the grain yield and biomass of maize. Applying the coated urea with polyphenol also decreased nitrate concentration of the soil during early growth stages and increased its availability during advanced stages of growth.

In spite of its economic value and various medicinal effects, flax (Linum usitatissimum L.) has been classified as a neglected crop during recent years. Therefore, it is necessary to improve grain yield and product quality indices along with reduced amounts of chemical inputs. In comparison with the control treatment (no fertilizer), application of chemical nitrogen increased flax grain and oil yield, respectively, by as much as 37% and 21%. There are several reports covering the grain yield increment of different crops influenced by organic fertilizers (Kumar et al., 2009; Sajadi Nik et al., 2011). As Mohanty et al. (2006) have reported, the phosphorus content in groundnut seed and phosphorus uptake in the whole plant have improved more under vermicompost treatment as compared to chemical fertilizer. Pirzad et al. (2013) reported that Fe foliar application increased the grain and essence yield of Anise (pimpinella anisum L.). Investigation of the possible reduction in chemical fertilizer application in flax production, and studying the plant response to integrated nutrition, were considered as the main objectives of the current study.
In order to study the effect of organic, chemical, biological and integrated nutrition systems on grain yield and quality of flax (Linum usitatissimum L.), a field experiment was conducted at the research field of Tarbiat Modares University (located on the Tehran-Karaj freeway, 16 km West of Tehran) during spring and summer 2013. The experiment was carried out as randomized complete block design with three replications. The treatments consisted of a control (no fertilizer), providing all nitrogen requirement from a chemical source (urea), from biological source (nitroxin), from an organic source (vermicompost), integrative nutrition 1 (urea nitroxin), integrative nutrition 2 (vermicompost urea), supplementary chemical nutrition (urea 緫殊娧 combi 2 micronutrient) and integrative supplementary nutrition (nitroxin urea fetrilon combi 2 micronutrient).
The results of analysis of variance indicated there were significant effects of nutritional systems on almost all traits such as grain yield, biomass, number of capsule per plant, number of branches, capsule weight per plant, 1000 seed weight, leaf dry weight, oil yield, oleic acid and linolenic acid (omega 3) content. The highest grain yield (703.08 kg. ha-1) was obtained under the chemical nutrition system, followed by the integrated (50% vermicompost % urea) and supplementary integrative nutrition systems (nitroxin urea 緫殊娧 combi2). Overall, these results suggest that the application of supplementary integrative nutrition increased flax grain yield and improved quality (13.05 % linoleic acid and 47.28% linilenic acid ) of flaxseed oil (65.7% compare to control). This treatment produced the highest oil yield (271.9 kg ha-1).
According to the findings of this research, integrative nutrition (nitroxin urea fetrilon combi 2 micronutrient) could be introduced as a good alternative for conventional methods of soil fertilization and will be considered as a forward step towards the goals of sustainable agriculture.

In the present study, energy analysis was applied to compare and contrast resource use, environmental impact, and overall sustainability in three systems of grain corn (Zea mays L.), wheat, and forage corn at Dezful County in Khuzestan Province, Iran.
As a top-down systems approach, the general methodology of energy evaluation consists of three steps: The first step in the application of the energy methodology is to construct system diagrams to identify all components and their relationships. The second step is to build the energy table, placing the numerical value and the units of each flow mentioned in the diagram; this table allows for the conversion of all the resources in terms of solar energy Joules using transformities (Odum, 1996). The third step is to obtain the energy indicators in order to evaluate the system’s environmental performance. In many studies, energy related indices have been introduced to assess various aspects of the sustainability of a system (Chen et al., 2006; Odum, 1996). The main indices used to explore the sustainability of agriculture are the Energy Yield Ratio (EYR) and the Environmental Load Ratio (ELR); when combined in the Sustainability Index (SI), these give a general measure of ecological sustainability. For the collection of data for the use in the analyses, field experiments were set up and the data were collected from approximately 243 fields representing grain crops, spring forage corn and wheat in Dezful County of Khuzestan Province, Iran. The information collected includes data related to agricultural management techniques, socio-economic data that cover costs related to management techniques and the prices attainable for crops, crop yield, and details that describe the land areas within and outside the cropping area. Climatic data for this research has been obtained from the National Climate Centre. Energy unit values (or energy intensity values) were extrapolated from previous research (Ulgiati and Brown, 1998, Alipour et al., 2012).
Results showed that energy yield ratios in winter wheat, grain corn and forage corn were 1.49E16, 1.57E16 and 1.59E16 Mj per hectare, respectively. The highest energy inputs in all systems were irrigation and fertilizers which were 86%, 87% and 82.8% of the total inputs of energy in wheat, forage corn and grain corn, respectively. An environmental loading ratio (ELR) was obtained for wheat, grain corn and forage corn of 0.49, 0.86 and 0.57, respectively and the energy sustainability index (ESI) was obtained for wheat, spring forage corn and grain corn at 4.99, 4.12 and 2.06, respectively. Results indicated that wheat production is the most sustainable system in terms of energy indices because it has the lowest environmental loading and highest environmental health. Results showed that the sustainability of these systems is acceptable because of higher share of irrigation in their energy flow.
According to several energy indices, of the three systems evaluated the wheat system had the greatest level of sustainability. A sensitivity analysis showed that the energy inputs of irrigation water and fertilizer were the highest sensitivity factors influencing the energy ratios. Best management practices, alongside other agro-ecological strategies, could be implemented to make further improvements in the sustainability of the three systems. In this regard, Integrated Plant Nutrient Management (IPNM) (such as manure, compost, artificial enrichment with CO2, genetic selection or inhibition of photo respiration and night respiration) can either improve the nutrient balance or minimize the negative impact of the fertilizers, playing an important role in all levels of agro-ecosystem.

Heavy grazing including activities can threaten plant species diversity and selective grazing of livestock can lead to a steady rise in non-palatable vegetation and, as a consequence, the dominance of a few species in a region (Anderson and Hoffman, 2007). To assess the impact of environmental factors on different ecosystem species, diversity measurement methods can be used. In fact, the species diversity in an ecosystem reflects the impact of various environmental factors on ecosystems and their status (Hasenauer et al., 2000). Nowadays, overgrazing can be observed in meadows and pastures surrounding the Golestan National Park (Akhani, 2005) and this could become a serious threat to the ecosystem of the region.
Considering the importance of the above, In order to understand the different contributions of various components of diversity and the composition of plant communities in different habitats under a grazing gradient, an experiment was conducted in Golestan National Park (the Park) and surrounding areas during 2011-2012. To this purpose, four habitat types were selected consisting of: un-destroyed habitat in the Park, abandoned habitat (areas of the Park that have been uninhabited since 1963), habitat under seasonal grazing (Ghorkhod Protected Area and surrounding areas) and heavy grazing in villages surrounding the Park. Six replications were determined for each habitat. Species richness and percentage of canopy cover were measured using 1 m2 sampling plots at each replication. In this experiment, SHE analysis was used to separate the components of diversity. In addition, to gain more awareness about species composition of the different habitats correspondence analysis was used for ordination.
The results showed that diversity and species richness reduced with increased grazing intensity in the study habitats. In addition, the frequency distribution of species in the un-destroyed and abandoned habitats and in habitats under seasonal grazing was fitted to a log normal model, and for the habitat with heavy grazing it was fitted to a logarithmic series model. Based on the logarithmic series distribution model most species have been observed in lower abundance and a few species have a maximum frequency which underscores the dominance of a small number of plant species. This is the reason why plant species composition in habitats under heavy grazing tends towards the non-palatable species. In an experiment conducted by Todd and Hoffman (1999) heavy grazing led to reduction of palatable species. In addition, the composition of plant species from different habitats was various and the similarities between species and families were different in the diverse habitats: The species and families recorded in habitats under heavy grazing bore the greatest similarity to species and habitats belonging to seasonal grazing, abandoned and un-destroyed habitats, respectively.
The results show that excessive exploitation by grazing has led to the reduction of plant species diversity and a change in the composition of plant communities in the Golestan National Park and its surrounding area. Therefore, more attention to this destruction of the genetic reservoir would appear to be necessary.

Sustainable agriculture is the proper management of agricultural resources that meets the needs of human and guarantees the quality of agricultural production and environment and also retains the capacity of soil and water resources (Naghipoor Dehkordi et al., 2016). Hitherto, various research studies have shown the positive effect of intercropping on greater use of the land (LER), leaf area index and total dry matter, growth parameters, yield and other things. The people of the world turning to medicinal plants in recent decades along with numerous advantages of intercropping for monoculture have attracted the attention of farmers to the production of the medicinal plants via intercropping (Malik et al., 2011). Therefore, the objective of this study was to evaluate growth indices for three species of black seed (Nigella sativa L.), borage (Borago officinalis L.) and marigold (Calendula officinalis L.) in replacement intercropping series.
Materials and metods: This experiment was conducted at the research field of Ferdowsi University of Mashhad during growing season of 2013-14. Treatments included double intercropping of black seed-marigold, black seed-borage and borage marigold-borage with ratios of 50:50, triple intercropping of black seed-marigold-borage with ratios of 33:33:33 and their monoculture. A weekly irrigation period was conducted and destructive sampling was carried out every two weeks. Measurement of daily changes in growth indices was done using relevant functions and Slidewrite and MS Excel were used, respectively, to fit functions to data and draw the figures.
The results showed that the highest amount of leaf area index (LAI) and total dry matter (TDM) of each plant of black seed, marigold and Borage was dedicated to their monoculture and the lowest amount of these was obtained through triple intercropping. The reason for this result could be related to reducing of the density of any studied plants in double and triple replacement intercropping. However, despite these results, the highest numbers of other growth indices such as relative growth rate (RGR), crop growth rate (CGR) and net assimilation rate (NAR) was obtained in intercropping treatments in which the highest value for each plant of black seed, marigold and borage was obtained in the triple intercropping treatment. Commenting on the present results, it can be noted that in intercropping due to more occupying of niches by crops, fewer niches can be gotten to weeds, so by reducing the number and density of weed species and avoiding the competition and their interaction with crops, can cause improved growth conditions for plants in intercropping. On the other hand intra-specific competition in intercropping are minimized and the positive impacts of intercropped species on each other leads to improvement in growth and, thereby, improvement of the growth indices.
The results showed that, although leaf area index and total dry matter of intercropping treatments were lower than in monoculture due to the lower density of black seed, marigold and borage in replacement intercropping compared to their monoculture, due to the plants’ improved growing conditions in intercropping treatments, both the crop growth rate and net assimilation rate of the plants in intercropping treatments were higher than in monoculture. It has been proven that the effects of intercropping by its involvement in improved soil quality, increased carbon sequestration and reduced leaching of nitrogen has contributed greatly to agro ecological services (Cong et al., 2015). The results confirm the better environmental resources use of black seed, marigold and borage in intercropping treatments and their considerable effect on growth indexes of studied plant. Thus, according to the results, it seems that intercropping, especially triple intercropping of black seed, marigold and borage, can be used for ecological resource management.

One of the best ways to increase production per unit area or, in other words, ensure the optimum use of land is the identification and selection of the most appropriate land uses based on their production capacity. With regard to the high economic importance of corn and this crop’s role in human, livestock and poultry nutrition and its many uses in the pharmaceutical industry and in order to emphasize the importance of identifying suitable areas for the sustainable production of this crop, this study was conducted. Its objective was to identify suitable areas for corn cultivation in agricultural lands of Aliabad Katool township, GolestanPprovince using spatial analysis tools available in ArcGIS.
Material and In this study, the environmental components included: average, minimum and maximum temperatures (annual and growth season of corn); annual precipitation; and soil characteristics such as organic matter (OM), EC, depth and texture. Then, all layer overlaid and zoning of lands was carried out in four classes (highly suitable, suitable, less suitable and unsuitable) and this classification demonstrated the crop adaptation with environmental factors.
Through comparison of different interpolation methods, the results showed that Kriging was the best model for identifying the distribution of precipitation and temperature in Aliabad-Katool township. Moreover, Universal Kriging (UK) was the best model based on the existence of the trend existing between climatic data due to topographic conditions. Many parts of the study area were classified as highly suitable and suitable zones according to the agro-ecological requirements of corn. The results showed that there is no temperature limitation, and all the regions were fitted to the highly suitable class. The interpolation of soil variables results demonstrated that, about 69.2 percent of agricultural land (including the northern township) and 83.5 percent of total land area, with the exception of the north-eastern regions, were classified in the highly suitable zone based on both OM and EC. The results showed that 55.58% of this region was high suitable and suitable for corn cultivation since the minimum, maximum and average temperatures and OM were suitable for this crop’s production in these classes. Also, the smallest (13.86%) area of unsuitable zone was located in the southern central part of this township. Etedeli and Givi (2012) indicated that environmental factors such as the average minimum temperature of growth period, sunshine during the growth stage, some land units and pH played major roles in reducing the utility of land for corn production in the Shahre Kord region. Based on the study by Yitbarek et al. (2013), Soil depth, moisture and fertility were the most important limiting factors in the physical assessment of land suitability for cotton, corn, upland rice and sorghum in Abobo region, western Ethiopia. According to these results, this region had moderately suitable conditions for the cultivation of corn. In agro-ecological zoning for canola dry-land cultivation in Lorestan Province conducted by Esteghfari (2008), the IDW method was used for mapping the environmental variables. In this research, maps of annual rainfall, mean annual temperature, mean minimum temperature, soil pH and slope were prepared and finally overlaid, then suitable areas for canola cultivation were determined for Lorestan Province.
Finding the results of soil and climatic variables and adapting them to the agro-ecological requirements, showed that the northern regions of Aliabad Katool are highly suitable for cultivation of corn. In fact, as much as from the North to the South of the township the capacity of the land for cultivation of corn had been reduced. In this area, some unsuitable classes of texture were identified as the main limiting factor. In general, climatic factors were identified as suitable variables for corn cultivation in the agricultural lands.

In recent years, the diamondback moth (Plutella xylostella) has had some outbreaks in Iran (Afiunizadehand Karimzadeh, 2015). As a consequence of the development of insecticide resistance in P. xylostella populations and high insecticide residue on the crops, alternative, ecological and sustainable pest management strategies are urgently needed (Talekar and Shelton, 1993). Cultural control is simple, applied and compatible with other ecological methods and, hence, it can be used in integrated pest management. Trap cropping is a cultural and ecological pest management strategy that has been used increasingly in recent years (Shelton and Badenes-Perez, 2006).The present study is aimed at examining an ecological management of P. xylostella using native plants as trap crops in common cabbage.
For this purpose, an experiment with six treatments was performed in a 0.5-ha field of common cabbage located in Falavarjan (Isfahan Province, central Iran). In each 100-m2 plot, the first two rows were planted with a trap crop, including Chinese cabbage, white mustard, turnip, black radish, and a mixture of all the aforementioned trap crops. Common cabbage was considered as the control. The treatments were replicated four times in a randomized complete block design. Random sampling was performed fortnightly from transplantation to harvest on 10 plants of main crop (common cabbage) per plot looking for P. xylostella larvae and pupae, and on three plants of trap crop per plot looking for P. xylostella adults.
For this purpose, an experiment with six treatments was performed in a 0.5-ha field of common cabbage located in Falavarjan (Isfahan Province, central Iran). In each 100-m2 plot, the first two rows were planted with a trap crop, including Chinese cabbage, white mustard, turnip, black radish, and a mixture of all the aforementioned trap crops. Common cabbage was considered as the control. The treatments were replicated four times in a randomized complete block design. Random sampling was performed fortnightly from transplantation to harvest on 10 plants of main crop (common cabbage) per plot looking for P. xylostella larvae and pupae, and on three plants of trap crop per plot looking for P. xylostella adults.
Considering the great concerns over overuse of chemical insecticides, it is necessary to use the cultural procedures of pest management, such as trap cropping. Trap cropping provides a simple and applied tool, which is compatible with other ecological pest management strategies.

Cereals are the dominant crops in world agriculture and are the major source of calories and protein to the diets of humans and livestock. Rice (Oryza sativa L.) is the second most important cereal in the world and it is is generally considered a semi-aquatic annual plant. The growth period of rice varied from 2-8 months, depending on the variety and environmental conditions with two distinct phases, namely vegetative and reproductive (including ripening). The dependence of conventional agricultural systems to intensive using of inputs and energy is one of the main reasons creating environmental impacts such as climate change, eutrophication, acidification and global warming. Effective use of energy resources in agriculture is one of the principal requirements for sustainable development; it will minimize environmental problems, prevent destruction of natural resources and promote sustainable agriculture as an economical production. Energy consumption in agriculture has been increasing in response to the limited supply of arable land, increasing population and a desire for higher standards of living (Karkacier and Gokalp Goktolga, 2005; Kizilaslan, 2009; Smil, 2008).
This study was conducted to study the energy indices and global warming potential of rice at the first and second planting patterns in Sari city through a questionnaire conducted during 2014. Inputs and outputs were converted to energy values using coefficients and the indices studied included the input energy (IE), output energy (OE), energy use efficiency (EUE), energy productivity (EP), special energy (SE), net energy (NE), direct energy (DE), indirect energy (IE), renewable energy (RE), non-renewable energy (NE) and global warming potential (GWP) of rice at the first and the second planting patterns. Cronbach's alpha coefficient was calculated as a tool for the reliability assessment.
Cronbach's alpha coefficient for the questionnaire was calculated as equal to α=%85. The results showed that input energy for the first and second planting patterns was 55332 and 56858 MJ ha-1 and their output energy was 80377 and 48926 MJ ha-1, respectively. Energy use efficiency and net energy for the first planting pattern were calculated as 1.45 and 24945 MJ ha-1 and, at the second planting pattern, these energy indices declined to 0.86 and -7923 MJ ha-1, respectively. Energy productivity in the first planting was calculated at 0.07 kg MJ-1 and it was 0.04 kg MJ-1 for the second planting. Special energy was 13.83 and 23.89 MJ kg-1, respectively, in the first and second patterns. The first planting pattern was more efficient in terms of energy consumption than the second pattern which was related to inputs and paddy yield. The global warming potential for the first and second planting patterns was computed as 990 and 1187 kg equiv. CO2 ha-1, respectively. Global warming potential for these planting patterns was 248 and 498 kg equiv. CO2 per t paddy yield, respectively.
Energy analysis of rice in the first and second planting patterns showed that input energy in the first planting pattern was lower than in the second pattern, but paddy yield in the first planting pattern was higher than in the other planting pattern. Both energy efficiency and productivity for the second pattern are low. The global warming potential in the second crop planting was higher than in the first planting pattern which was due to the consumption of inputs and energy.

Rapeseed cultivation is considered important and the area under its cultivation is on the rise. Weeds commonly occur in rapeseed fields and their infestation is a major yield reducing factor. Weeds with branched, vigorous root systems inhibit the development of rapeseed plants through severe nutrition deprivation (Roshdy et al., 2008). Usually, rapeseed weed management is done with using mechanical, chemical, and biological methods and the combination of these methods increases the weed control efficiency. A combination of a stale seedbed technique with chemical and mechanical methods in rapeseed cultivation can be an efficient method, because the stale seedbed allows weeds to germinate in straw or a cultivated field and can then destroy them by tillage or herbicide before planting rapeseed. The purpose of this research was to evaluate the effect of the combination of cultural weed control with mechanical and chemical methods for the weed control of rapeseed.
This study was conducted during the 2008 and 2009 growing seasons at Safiabad of Dezfol and Darab of Fars. The experimental design was a randomized complete blocks with a split-plot arrangement with 12 treatments and three replications. The main factor comprised a weed control method at six levels, including: 1- pre-planting irrigation mechanical weed control, 2- pre-planting irrigation Treflan (Trifluralin EC48%) at 2lit ha-1 pre-planting and soil incorporated Galantsuper (Haloxyfop R methyl Ester EC10.8%) at 0.75lit ha-1 post-emergence, 3- pre-planting irrigation Gramoxone (Paraquat SL20%) 3lit ha-1 post-emergence, 4- Treflan at 2lit ha-1 pre-planting and soil incorporated Galantsuper 0.75lit ha-1 postemergence, 5- Weedy check and 6- Weed-free check. The sub-plot contained a sowing date at two levels, including: an early sowing date and a Late sowing date.
Results of the experiments showed that, in Darab, the early sowing date was the best date for sowing rapeseed while, in Safiabad, the sowing date had no effect on weed control and yield. In Darab at the early sowing date, pre-planting irrigation mechanical weed control (2145 kg ha-1) and pre-planting irrigation Gramoxone (1875 kg ha-1) were the best treatments for rapeseed yield. Weed control also showed the same trend. In Safiabad, rapeseed yield in pre-planting irrigation treatments (mean 2300 kg ha-1), herbicide treatment (2128 kg ha-1), without weed control treatment (2242 kg ha-1) and weed control treatment (2634 kg ha1) had no significant difference. Weed control for most of weeds showed the same trend.
Hence, it seems that planting rapeseed in proper time can give rapeseed a competitive power through the development of a broad canopy and shade over weeds in the early stages of the weeds, so that it is not even necessary to control weeds. However, when rapeseed cannot compete with weeds, a combination of stale seedbed with chemical and mechanical methods at the proper planting time is efficient. Rapeseed plant traits are associated with competitiveness and allelopathy (Asaduzzaman et al., 2011) and competitive ability is evaluated by the ability of plant morphological traits to improve access to scarce light, nutrients and water in a limited space (Asaduzzaman et al., 2014).

Conventional soil tillage (CT), such as mouldboard ploughing and rotary ploughing aggressively disturb the surface soil layer every year. In the short term, these systems create a good soil physical environment for crop emergence, rapid early growth, nutrient uptake, and high crop yield (Six et al., 1999). However, over the long term, the soil structure becomes degraded and soil organic matter (SOM) mineralization is increased, leading to SOM and nutrient content depletion, soil compaction and soil erosion (Triplett and Dick, 2008). All of these processes degrade well-structured soil and obstruct farmland sustainability (Fernandez et al., 2009). Hence, adoption of conservation tillage practices, for example no-till (NT) and reduced-till (RT), has been widely accepted over the last two decades in selected areas (Triplett and Dick, 2008). Conservation tillage improves economic performance and energy use efficiency, and reduces production risks; it also decreases soil disturbance, improves SOM maintenance and benefits soil quality (Zentner et al., 2004). Lafond et al. (1996) reported that conservation tillage increases pea, flax and spring wheat grain yields.
Considering that there is little information available about the differences in variety with the ability to allocate between the main stem and branch yield response to tillage systems, a field experiment was therefore conducted in 2014 on a split factorial in a randomized complete block design with three replications at the research farm of the College of Agriculture and Natural Resources of Tehran University in Karaj. The main factor includes two types of tillage systems (conventional tillage and no-tillage) and the subplots of three cultivars (L17, Williams, Nekador); the third factor was priming (priming with potassium nitrate 0.4 %) and no-priming (control) to the factorial in the main plots were broken. In this experiment, characteristics such as the number of branches per plant, yield and yield components on the main stem and branches were measured.
Plant density (m-2) was significantly affected by the interaction between the seed priming and tillage system, and the effect of the choice of cultivar as well. The interaction between tillage system, cultivar and priming was statistically significant on the number of seeds in the pod, grain yield on main stem, number of seeds in the plant and thousand seed weight of soybean. In addition, interaction between seed priming and tillage system was significant on the thousand seed weight on the main stem and grain yield of branches. The number of pods in the plant and the grain yield of branches were influenced by the interaction between cultivar and tillage system, while the number of seeds in the plant and the grain yield of branches were affected by interaction between the cultivar and priming. The effects of cultivar and tillage systems were significant on the number of branches on the plant and grain yield on the main stem. Final grain yield on the main stem and branches of soybean were affected by the tillage system, cultivar and priming.
Maximum plant density (25 plants in m-2) was observed when the conventional tillage system was used under control conditions. Seedling establishment of soybean was lower as the result of seed priming and tillage system. The maximum grain yield was observed in L17 under the conventional tillage system and without seed priming, but Nekadar produced the minimum grain yield. Non-priming of the seed (control) in the normal tillage system produced the maximum grain yield in branches and primed seeds of soybean under the conventional tillage system produced the minimum grain yield. The grain yield of branches under the normal tillage system was higher than with the conventional tillage system in the Williams cultivar. The maximum contribution of grain yield under the conventional tillage and normal tillage systems was related to main stems and branches, respectively.

Intercropping is an example of a sustainable system in agriculture that has such purposes as creating ecological balance, higher utilization of resources, increase in the quantity and quality of the product and reducing pests, diseases and weeds (Koochaki and Zand, 1996). Persian clover (Trifolium resupinatum L.) is a plant native to Asia and Iran and contains both early (single cut) and late (multiple cut) ecotypes (Taylor, 1985). One new method in intercropping, namely the interspecies intercropping of different cultivars of Persian clover that causes an increase in the yield. However, little known about this method in the litreture (Prasad et al, 1990). The objective of this study was to investigate the effect of intercropping of early (single cut) and late (multiple cut) ecotypes Persian clover cultivars on quantitative and qualitative forage yield and determe the best seed rate and seed mix in the Karaj region
In order to evaluate the effect of interspecies intercropping with Persian clover cultivars on increased forage yield, an experiment was carried out at the Seed and Planting Improvement Institute as a factorial design (base on a randomized completely block design (RCBD) with two factors (mixed seed at 5 levels, including 0-100,100-0,50-50,40-60,and 60-40 and seed rate at 3 levels of 10,15 and 20 kg ha-1) over two years (2012-13).
The results of combined analysis of variance showed that the effect of year, seed rate and seed mix rate on the forage and dry matter yield and protein percentage, and the interaction of seed mixed × seed rate for just the protein percentage, were significant at 1% probability levels. Mean comparison of seed mixed × seed rate showed the highest forage and dry matter yield with 68.19 and 12.02 t ha-1 were obtained, respectively, from the treatment of 60% Persian clover (single harvest) and 40% multiple harvest Persian clover and seed rate 15 k ha-1. Also, the lowest forage and dry matter yields of 42.52 and 5.18 t ha-1 were obtained from the treatment of 100% multiple harvest Persian clover and the seed rate of 10 kg ha-1, respectively. The quality results showed that the highest crude protein at 24.77% was obtained from the treatment of 100% multiple cut harvest Persian clover and a seed rate of 10 kg ha-1. Evaluation of the land equivalent rate (LER) showed the highest evaluation efficiency at LER=2.85 was obtained from the treatment of 60% Persian clover (single cut) and 40% multiple cut harvest of Persian clover and a seed rate 10 kg ha-1, and for crude protein from the treatment of 40% Persian clover (single cut) and 60% multiple cut harvest Persian clover and a seed rate of 15 kg/ha with LER= 2.17, respectively.
The results of this study indicate that interspecies mixed cropping of early and lately cultivars of Persian clover resulted in inceased forage yield compared to pure cropping. Since early cultivars have high a growth rate and suitable water and soil resources for utilization and high biomass production, in intercropping with late cultivars resulted in increased forage production in time and place units. The highest forage of 68.19 and LER=2.68 for forage yield, 12.02 t ha-1 and LER=2.85 for dry matter yield were obtained from the treatment of 60% Persian clover single cut and 40% multiple cut Persian clover and a seed rate of15 k ha-1. This mixed cropping model could be an agro-ecological approach for high forage production in crop systems.

Most farmers use various management strategies to minimize weed damage, and such management practices can have direct or indirect impacts on biodiversity in agricultural ecosystems (Koocheki et al, 2006). Use of various mulch and tillage methods with the application of herbicides causes greater confidence in effective weed control and can be used as one of the major methods of weed control in potato crop (Bellinder et al, 2000). The aim of this study was the evaluation of weed composition under the influence different kinds of weed management methods in potato crop.
The experiment was performed in 2015 on two locations at the agricultural research stations of Alarogh and Samian in Ardebil Province in a randomized complete block design with three replications. The treatments included 1) spraying Trifluralin between potato rows, 2) spraying Metribuzin between potato rows, 3) cultivator practice between planting lines, 4) usage of plants containing wheat stubble, 5) usage of plants containing Canola stubble, 6) usage of black polyethylene mulch, 7) usage of transparent polyethylene mulch and 8) control (no weed control in all growth duration) treatment.
From 12 weed species observed in this study, Common Amaranth (Amaranthus retroflexus), Common lambsquarters (Chenopodium album), Bindweed (Convolvulus arvensis), Green foxtail (Setaria viridis), Prickly lettuce (Lactuca seriola), Russian knapweed (Acroptilon repens) and Milk thistle (Sonchus arvensis), were dominant with the highest rate of weed prevalence. The averages of any ShannonWiener and Simpson indices were changed in both locations so that only the diversity of the Shannon-Weaver index showed a statistically significant difference with change in the kind of weed management. The greatest diversity of both indices was observed in weed infested treatment. Based on the results of Baskin et al (2004) and Milberg (1997), lack of weed control in farmland or fallow land increased weed density and caused an increase in weed density and can also have an effect on species diversity. Based on the Shannon-Wiener index the treatments comprising the use of Trifluralin, cultivators and transparent plastic with values of 1.11, 1.04 and 0.99, respectively, after the weed infested treatment had the highest species diversity. The lowest number of weed species based on the Shannon-Wiener and Simpson indices, similarly, was related to the treatments of canola stubble mulch, Metribuzin herbicide and black plastic mulch, respectively. Hence, with potato weed density at both stations being significantly under the influence of experimental treatments, the mulch, herbicide and cultivator treatments had a significant effect on potato weed density in both locations so that the lowest density of weeds was obtained in wheat stubble mulch and canola stubble mulch. The density of Common Amaranth, Common lambsquarters and Bindweed species, all important weeds, decreased in all mulch, cultivation and herbicide treatments as compared to the weed infested treatment. The highest Common Amaranth density was observed in the treatments of black plastic mulch, Trifluralin and transparent plastic mulch, respectively. Common lambsquarters had the highest density under Metribuzin herbicide treatments.
In this study, density of annual weeds was higher than that of perennial weeds; in other words, the highest density of weeds was related to annual weeds. But canola stubble reduced weed density and biomass more compared with the control to the amount of 83 and 81 percent, respectively, and the wheat stubble application reduced weed density and weed biomass to the amount of 79 and 84 percent, respectively. This shows that the use of herbicides, plastic and plant mulch and cultivator can significantly reduce weed density and biomass.

Large areas in Iran which located in arid and semi-arid region are faced with serious water shortage. Because in these regions, from one side the precipitation and access to water resources are limited and from the other side atmospheric factors are intensively influence evaporation. In addition, evaporation from soil surface not only wastes water resources, but also may cause soil salinity (Homaee et al., 2002; Hillel, 1998). The objective of this study was to estimate evaporation from bare soil at presence of different water table levels. The rate of evaporation loss was also estimated, using the parametric model proposed by Zarei and Homaee based on Brooks and Corey’s retention curve.
For this purpose, the cumulative and instantaneous evaporation in a sandy loam soil was measured by weighting method three times a day. The proposed model of Zarei and Homaee was further tested against the collected experimental data. This retention-based model has been proposed to estimate evaporation from water falling table.
Results indicated that the maximum and minimum efficiency of model, obtained under 150 and 75 centimeters of water table depth, were 98 and 81 percent, respectively. The results showed that at water table depths less than one meter, the evaporation rate is increased. The results also indicated a reasonable agreement between the measured data and model outputs. The small difference between the measured and predicted values may be attributed to the moisture movement as vapor, soil shrinkage and errors in digital scale measurements. The predicted instantaneous evaporation rates provided better agreement with the experimental data as water table depths increased.
The parametric model of Zarei et al. (2010) provided a reasonable agreement with the experimentally measured evaporation data. Consequently, this model can be used to estimate the evaporation under similar climatic conditions.

One serious challenge in agriculture during the 21st century is meeting the food demands of the growing population from restricted and decreasing per capita natural resources such as land, water, and minerals with minimum environmental degradation. But, developments in agriculture that heavily rely on chemical inputs such as synthetic fertilizers, pesticides, fossil fuels and other energy-intensive inputs, is having a serious impact on public health and the environment. Therefore, efficient use of resources and inputs is a primary and most vital implications for sustainable development of agriculture. Sustainability indices are quantitative values that can be used to evaluate the efficiency and quality of agroecosystems and are useful tools for making suitable decisions in its management (Mahdavi Damghani et al., 2006). These including energy flow indices, global warming potential (GWP), economic indices, environmental impact quotient (EIQ) of pesticides, efficiency of land, water and fertilizers use and etc.
In the present study, the sustainability of wheat and barley production systems lies in the Maragheh-Bonab plain in southern East Azerbaijan province in northwestern Iran were evaluated using the aforesaid indices. For this purpose, data was collected from 110 farmers by survey to determine crop production in the region. Secondary data was obtained from previous studies and statistics from organizations such as the Agricultural Ministry of Iran.
The results showed that the values of input energy, output energy and net energy in wheat production system (34412, 161462 and 127050 Mj ha-1, respectively) were higher than barley production system (29596, 126077 and 96480 Mj ha-1, respectively). Also, it was observed that the values of energy use efficiency and energy productivity of wheat (4.7 and 0.17 kg MJ−1, respectively) were significantly higher than that of barley (2.1 and 0.15 kg MJ−1, respectively). In terms of economic indices, despite of lower total cost of production in barley, the highest values of gross production value, net return, benefit to cost ratio and economic productivity were related to wheat production system. Our results are in agreement with the results of Sahabi et al. (2013). In terms of GWP and EIQ, wheat production had the higher values with compared to barley production. However, eco-efficiency (ratio of economic value to the environmental impact) values based on of GWP and EIQ was significantly higher for wheat (1.26 $ kg -1 CO2eq-1 and 37 $ EIQ-1) than barley (1.03 $ kg-1 CO2eq-1 and 31.4 $ EIQ-1). Also, land, water and fertilizer use indices for wheat were higher than barley. The land use efficiency, land production efficiency, economic land production efficiency, irrigation water productivity, economic irrigation water productivity, nitrogen use efficiency, phosphorous use efficiency and potassium use efficiency were 65.7%, 24.5 kg ha-1 day-1, 6.2 $ ha- 1 day-1, 1.6 kg m-3, 0.43 $ m-3, 56.7 kg kg-1, 136.4 kg kg-1 and 2401 kg kg-1 in wheat production system and 61.6%, 19.2 kg ha-1 day-1, 3.2 $ ha-1 day-1, 1.5 kg m-3, 0.26 $ m-3, 34.8 kg kg-1, 102.3 kg kg-1 and 376 kg kg-1 in barley production system, respectively.
It can be concluded that environmental impacts of pesticides and global warming effect per area in barley production system were lower than wheat production system. However, in terms of economic indices, inputs and energy use efficiency, wheat production system was superior to barley production system.