mehdi nassiri mahallati

Following population growth and increasing demand for food, agricultural systems have been considerably altered across the world. Nonetheless, the majority of these changes have been accompanied with many consequences by reason of focusing on economic growth and ignoring the relation between humans and environmental wellbeing. Thus, it seems that any future increase in food production should be done in a sustainable way which considers various issues. Based on this viewpoint, understanding the importance of diverse women’s roles and addressing gender equality are indisputable preconditions for achieving sustainability in the agriculture sector. Women significantly affect the welfare and sustainability of farmer households through numerous tasks assigned to them by societies. However, women do not have the same rights as men in access to productive resources because of gender-based norms. Although the sustainability of agricultural systems has been evaluated by many researchers, they rarely used gender-based analyzes in their assessments. Hence, we aim to determine women’s participation in various agricultural systems and evaluate the impact of women’s activities on the sustainability of agroecosystems in Iran by using a comprehensive approach.

To explore answers to our research goals, a specific questionnaire was utilized, and its validity and reliability were approved by experts and the Cronbach’s alpha test, respectively. We used the purposive sampling method to identify townships and villages and applied the simple random sampling technique to select farmer households. Based on different methods and the results of pre-test surveys, 930 farmer households were considered as the appropriate sample size in this study. Because there are different climatic conditions, agricultural products and subcultures in Iran, this study was carried out in all 31 provinces of Iran to cover differences between regions. The sustainability of farmer households was assessed by applying 15 indicators. Then, scores attained by farmer households were simplified to define three principal thresholds for sustainability: unacceptable (scores≤ 1.5), limited (1.5 <scores≤ 2.5), and good (2.5 <scores). Women’s different activities in market-oriented (male-dominated) agricultural systems were ranked by the Friedman test. The correlation between women’s participation in male-dominated farms and the sustainability of farmer households was determined based on the Tao B. Kendall correlation coefficient. Moreover, the effect of women’s participation in female-dominated agricultural systems (home gardens) on the sustainability of farmer households was assessed by the independent samples t-test.

Results disclose that the majority of rural women are pushed back from market-oriented (male-dominated) agricultural systems, especially from cash crop and fruit production systems. Nonetheless, women continue to play a significant role in subsistence (female-dominated) agricultural systems, with 44.1% of them having home gardens. Our findings reveal that farmer households do not experience the good threshold of sustainability, but households whose women have home gardens succeed in gaining higher scores of sustainability than other farmer households. Home gardens, compared with male-dominated farms, put the minimum pressure on the environment because of their reliance on renewable energy inputs. In economic and social dimensions, women meaningfully improve the sustainability of their households by producing different crops and fruits in home gardens. Farmer households with home gardens are able to offer a wider variety of products for sale, make more profit, and even have better savings and liquidity. Home gardens can also increase women’s economic ability, which subsequently improves the food security, health and education of children. Women positively affect the sustainability of farmer households by participating in male-dominated farms. Nonetheless, women’s participation in these systems is not as effective on the sustainability of farmer households as their participation in female-dominated agricultural systems (home gardens).

Conclusion:

 Our findings indicate that women’s agricultural activities influence the sustainability of farmer households in a positive way. Therefore, we suggest that experts and policymakers address issues affecting the agriculture sector through a gender lens. Because, the marginalization of rural women from the agriculture sector means the transformation of rural women from economically active actors into consumers with a different lifestyle, which undoubtedly puts a lot of pressure on the economy, both locally and nationally. It will also lead to numerous environmental and social consequences.

Intensive agricultural systems are mainly monocultures with low sustainability because they neglect the mutual relationships between living organisms and the environment. Intensification in spatiotemporal dimensions and uncontrolled use of external inputs have created ecosystems with less diversity and greater vulnerability. Afghanistan has an agricultural-based economy and the food security of people is mostly dependent on national agricultural production. However, in recent years food production in the country has been threatened due to complicated political conditions. Proper use of biodiversity could enhance crop production in low-input systems. However, so far, no published information is available on this important issue. This study was conducted to evaluate the diversity of Afghanistan's agricultural production at the agroecosystem level.

In order to carry out this research, a countrywide data set was collected. In this research, the required data were extracted through collected questionnaires from 388 counties in 34 provinces of Afghanistan. For this purpose, all provinces and at least 10% of the counties located in each province were selected and evaluated based on the cultivated area of crop species across the provinces. In addition, the national registered information and the data available in the agricultural management centers of the provinces were also used. The existing production systems were differentiated using cluster analysis. The common crop rotations in different provinces were also extracted from the questionnaires and included in the relevant table.

The results showed that the provinces of Afghanistan are very similar in terms of the proportion of land allocated for cereal crop production. Cluster analysis indicated that the cereals cropping system is practiced across the country. According to the cluster analysis, since cereals have been allocated between a minimum of 41.2% (Maidan Wardak Province) and a maximum of 96.70% (Konar Province) and the agricultural system of Afghanistan is based on the cultivation of cereals especially wheat. Pulse, vegetables, industrial plants and forage crops respectively formed a maximum equal to 14.2%, 55.5%, 33.4%, and 38.2% of the cultivated area of other major agricultural products, respectively in Daikundi, Nimroz, Balkh and Logar provinces. The study of crop rotations showed that in most of the provinces, cereals are the dominant crops and other crops such as pulse, vegetables, industrial plants and forage crops are alternated as second crops along with cereals. Common crop rotations in the country are mainly based on wheat cultivation and do not have much variation among provinces. In addition to irrigated agriculture, dryland farming is also prevalent in this country, which includes 32% of all cultivated lands.

The results showed that the agroecosystems of Afghanistan are very similar to the neighboring countries, including Iran, and have been developed based on wheat cultivation. Also, the diversity is relatively poor at the level of agroecosystems, and their management is designed for the development of uniform irrigated agriculture in short-term crop rotations.Also,due to economic problems, agricultural production is managed in the form of low-input systems. Therefore, the most logical solution for poor farmers who do not have access to resources is to increase the level of species and genetic diversity in order to increase production without the need for external inputs.

The importance of rapid, non-destructive, and accurate estimation of leaf area (LA) in agronomic and physiological studies is well known. The need for such estimates of leaf area in particular for leaves with unusual shapes has led to studies relating leaf dimensions and leaf area. However, a search of literature revealed that little information is available for short day onion (Allium cepa L.). The objective of this study was to develop a statistically validated regression model for leaf area prediction from simple non-destructive measurements for onion cultivated in the South of Iran.

In order to prepare the required plant samples to measure leaf area parameters, an experiment was conducted in the cropping year 2020-2021 in a field of 300 square meters located in Hormozgan province-Rahdad district. The short-day cultivar Takii was used because of its wide planting area in the province. 40 leaves were chosen at random from plants growing in the farm, half were left for validation of the model and the other 20 leaves were subjected to measurement and calibration. The standard method (LICOR LI-3000C) was used for measuring the actual areas of the leaves. Before measuring the leaf area, two main parameters related to leaf length and width were accurately determined for each leaf. To select the best variables and the regression model for estimating leaf area, the fitted simple and multiple linear regression were subjected to the stepwise elimination method. Finally, the accuracy of the selected models was validated using the root mean square error (RMSE) and coefficient of determination (R2).

All linear models for estimation of leaf area with width (W) and length (L) as well as models including both variables were subjected to regression analysis. The results indicated that leaf length (L) is more appropriate variable for estimating onion leaf area and leaf width (W) was not able to properly describe leaf area. Based on the findings of this research leaf area estimation model with both W and L had the best prediction, with RMSE% = 8.64, RMSE= 1.76 and R2= 0.91. (Area= 0.121 + 0.01537 L2 + 0.3225 L×W).

As the understanding of plant growth and development has been increasing, such mathematical models will be very useful tools for the prediction of leaf area for many plants without the use of expensive devices. Thus, the models from the present study will enable researchers of plant growth modeling to predict leaf area non-destructively with the equations developed.Keywords: Leaf Area, Leaf Length, Leaf Width, Regression, Coefficient of determination.

Production and use of biodegradable films with appropriate physical and mechanical properties and replacing them with synthetic materials is an effective solution to reduce many environmental pollutions. In this study, with the aim of producing biodegradable consistent structure and durable composite films, starch, zein and PVA were mixed with different proportions according to mixture design and ternary composites were prepared.Physical and mechanical properties were compared and optimum formulation were determined. According to the results, adding PVA to starch improved the mechanical properties and adding zein to it reduced the water solubility of the composite films. The optimal formulation of the three-component composite was determined as 85% starch, 15% zein and 5% PVA with a desirability level equal to 98%.The x-ray diffraction patterns of optimal film showed two specified peak at 2θ = 17-19 ° and 2θ = 22-24°, this pattern indicated the amorphous and crystalline structure of the composite film. Finally, differential scanning calorimetry showed that the highest weight loss of composite film is 285/3-340°C equal to 48/2%.

Chemical fertilizers have played a significant role in increasing the yield of agricultural products, especially since the 1950s, but the excessive application of these fertilizers in recent years has led to environmental pollution and a drop in agricultural productivity, food security, ecosystem and human health, and economic prosperity. Researchers believed that the best and most accessible approach to solve these problems is the improvement of the efficiency indicators of inputs. So, the purpose of the study was to evaluate the use efficiency indicators for nitrogen and phosphorus and water in wheat-irrigated and dryland systems of Iran.

In this research, provinces with more than 80% production in irrigated and rainfed systems of Iran were determined and, in each province, cities with more than 80% production of this crop were selected. The required data were collected by using face-to-face interviews and recorded statistics. Afterward, the consumption productivity of inputs was determined, and then the Pearson correlation coefficient between the productivity of different sources was computed. Also, multiple regression was used to determine the relationship between yield with climatic variables and fertilizers and water. For this purpose, the two-year average for total precipitation for irrigated and rainfed systems in each region were extracted.

The results revealed that in the main areas of wheat production, the average productivity of nitrogen consumption for irrigated was calculated as 16.69 kg of grains per kg of nitrogen compared to 17.27 kg of grains per kg of nitrogen for rainfed conditions. Contrary to nitrogen, the efficiency of phosphorus consumption in rainfed agriculture was lower than in the irrigated wheat system. Also, the highest correlation between nitrogen and phosphorus productivity for the irrigated system was computed with r=0.506 and the coefficient between nitrogen and water productivity was calculated with r=0.309 for rainfed conditions. The results for regression analysis between yield and climatic and agronomic parameters showed that increases in temperature had a positive effect on grain yield in rainfed conditions. On the other hand, increasing in other parameters such as precipitation, nitrogen, phosphorus, and irrigation in the irrigated and rainfed systems had a direct relationship with grain yield.

Excess use of nitrogen fertilizers in irrigated wheat systems led to lower nitrogen use efficiency. Although, the grain yield in irrigated conditions was higher than in dryland conditions, due to the sensitivity of using nitrogen by farmers and the adverse effects of excessive use in rainfed wheat, the consumption of nitrogen has been used with more precision and sensitivity. This ultimately led to an increase in the efficiency of nitrogen consumption in rainfed compared to irrigated systems. Unlike nitrogen, the phosphorus use efficiency was lower in rainfed compared to the irrigated system due to the direct effect of soil moisture on the release of phosphorus in the soil. According to these results, nitrogen and water were the most important factors affecting the yield in irrigated and rainfed systems. Also, the regression analysis of the relationship between wheat yield and climatic and agronomic parameters showed that in irrigated systems, nitrogen and irrigation and in rainfed conditions, nitrogen and precipitation had the most impact on grain yield.

Meta-analysis is a comprehensive statistical analysis method for multiple independent experiments under the same subject. In the agricultural research field, the technique is mainly used for the comprehensive study of trials to explore the response characteristics of the main treatments (11). Due to the dispersions and differences in the results of studies on the effect of fertilizers on the growth and quantitative and qualitative yield of important medicinal species, in this study, meta-analysis method was used.

We conducted a global meta-analysis to evaluate the effect of various fertilizers on quantitative yield and quality of some medicinal plants including psyllium, fennel, basil, savory, dill, black seed and cumin using data obtained from peer-reviewed publication during past 50-year based on a ROSES protocol. So, 78 studies were selected that they representing 18 studies on psyllium, 8 studies on fennel, 12 studies on basil, 11 studies on savory, 7 studies on dill, 9 studies on black seed and 13 studies on cumin. Hedges effect size, publication bias (by using Begg and Mazumdar correlation) and Kendall's Tau coefficient were computed and funnel graphs were drawn by using Comprehensive Meta-Analysis software, version 2.

Based on the results, the highest effect size was related to the impact of humic acid on dried weight of stigma (g=3.434). After humic acid, biofertilizer, chemical fertilizer and compost were computed in the next ranks. Based on the Hedges effect size, vermicompost (g=1.106) had the highest impact on psyllium yield of and the next rank was computed for integrated fertilizers (g=0.061). Different fertilizers had not significant effect on yield of fennel and dill. The results revealed that bio-fertilizer (g=0.553) had significant effect on yield of black seed. Also, cumin yield was significantly affected by integrated and chemical fertilizers. Effect size values for manure, vermicompost and integrated fertilizers on mucilage percentage of psyllium were computed significant impact with 0.6, 0.9 and 0.7, respectively. Manure, bio-fertilizer and integrated fertilizers were also significant on essential oil content of fennel, black seed and cumin. The results of Begg and Mazumdar correlation revealed that the impact of chemical fertilizer was heterogeneous on cumin and these fertilizers are not recommended for the medicinal plant species. The effect of chemical fertilizer was calculated as homogeneous on leaf dried weight of basil. In other cases, the application of biofertilizer, vermicompost and manure are homogeneous and recommended for these crops with 95% confidence interval.

Totally, there was high residual heterogeneity in meta-analyses of soil fertilizers on different species of medicinal plants, suggesting that a large amount of further research with detailed analysis of soil physical, chemical and biological properties is also required to fully understand the influence of fertilizer treatments on growth, quantitative yield, and quality oil yield. This meta-analysis quantified the growth and yield of medicinal plant affected as different fertilizers based on available scientific evidence, providing a basis for improvement of medicinal plants management.

In order to evaluate the effect of temperature, drought and priming on the percentage and rate germination of corn seeds, a factorial experiment based on a completely randomized design with four replicates was conducted. Treatments included eight temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45 ºC), four drought potential (0, -0.4, -0.8 and -1.2 MPa), and five priming (control, hydroprimin, GA priming, ABA priming and, SA ptiming). Both percentage and rate of germination were inhibited at osmotic potentials ≤−0.8 MPa PEG. At 35 ºC temperature. Germination percentage of unprimed seeds was reduced from 94 to 36% in −1.2 MPa. Under these conditions, gibberellic acid hormone treatment improved seed germination. The effect of temperature on germination can be defined in terms of cardinal temperatures. We compared three non-linear regression models (Dent-like, segmented and beta). The outcome revealed that the Dent-like function was suitable for use in describing seed germination response to temperature. The base, optimum 1, optimum 2 and ceiling temperature were estimated to be 9.51, 24.12, 35 and 44.62 °C, respectively. The response of germination rate to both temperature and water potential can be described as a non-linear function of the hydrothermal model. According to the results of this study, hydropriming, gibberellic acid, and salicylic acid increased the mean deviation of the base temperature compared to non-priming treatment, increasing the standard deviation of the base temperature indicates the ability of seed germination in different osmotic potentials.

Introduction :           

The ecological footprint (EF) is an area of biologically productive land capable of meeting all human needs (food, clothing, and construction) and accommodating their production waste. Therefore, application of ecological footprint in combination with social and economic impact assessment can provide the basis for measuring triple sustainability indices (social, economic and ecological). Universities around the world are amongst the institutions that are increasingly focusing on promoting sustainability, and often use ecological footprints as a good indicator for measuring their sustainability. Universities are considered to be one of the largest consumers of paper, energy and water, and because they utilize these resources for education and research activities, it is expected that a sustainable university should have minimized adverse environmental, economic, social and health impacts and help society moving towards a sustainable life style. However, ecological footprint of Iranian universities is not documented. Therefore, the purpose of this study was to calculate the ecological footprint of students of Ferdowsi University of Mashhad as the third biggest university of the country.

Materials and Methods:                  

In this study, EF on the campus of Ferdowsi University of Mashhad (FUM) was calculated by using two standard international methods including Ecological Footprint Network (EFN) Questionnaire and Ecological Footprint Analysis (EFA). In EFN method the questionnaire designed by Global Footprint Network was used. In EFA method, the university information (consumption of energy, food, and construction) was obtained from the relevant departments and finally, the total footprint was calculated using the standard EF accounting method.

Results and Discussion:                                                

The results showed that total ecological footprint of the campus was 1.51 g/ha, which is less than reported values for the world (2.80) and national (3.20) footprints. This is due to the fact that students use public transportation services and produce less waste. On the other hand, due to the recycling of a significant amount of waste produced at the university, the energy footprint of university students has decreased, which has ultimately reduced the total footprint of students compared to the national and global levels. The EF in this study consists of three components i.e. energy, food, and build up. Among the components, food with 57.3% had the highest share of total footprint and therefore had the most significant impact on increasing the total EF. After the food footprint, the energy with 0.35 g ha (23%), had the highest share of total footprint. While the Build up with 19.7 g ha, had the least significant impact on increasing the total EF. There was no difference between the EF of males and females students. However, the footprint of bachlor students was higher than Msc and PhD students. Architecture students had the most (1.77), while theology students had the lowest EF (1.30 g/ha). Finally, the results of the present study show that Ecological Footprint is one of the appropriate indicators for measuring the sustainability of universities and can help managers and decision makers in universities to move towards sustainability goals.

 Conclusion :                                                                                

The EF is an accurate index for evaluation of environmental sustainability, and since reconsideration of the current lifestyles should be started from academic societies, planning for a detailed accounting of EF for university campuses over the country is required.

Optimization of fertilizer and plant density are management approaches to improve resources efficiency and decline environmental pollutions. Response surface methodology (RSM) is defined as a set of mathematical and statistical techniques that are used to develop, to improve or to optimize a product by using Central composite designs. In this work, optimization of cow manure and plant density on biomass yield and essential oil percentage of peppermint as a medicinal plant species using central composite design for RSM was evaluated.

An experiment was conducted using central composite design with 13 treatments and two replications at the Research Field of Ferdowsi University of Mashhad during the growing season of 2017-2018. The treatments were allocated based on low and high levels of plant density (10 and 15 plants.m-2, respectively) and cow manure (0 and 70 t.ha-1, respectively). Fresh weight of stem, dried weight of stem, fresh weight of leaves, fresh weight of leaves, total dried weight and essential oil percentage in two sampling times and two cuttings were measured as dependent variables and changes of these variables were evaluated by a regression model. Lack-of-fit test was used to evaluate the quality of the fitted model. The adequacy of the model was tested by analysis of variance. The full quadratic polynomial equation was tested to determine the significance of the model and the component of the model (linear, squared and first-order interaction terms) and the quality of the fitted model was judged using the determination coefficient (R2).

The results showed that effect of linear and square components were significant on all studied characteristics in two sampling times. Interaction between the two factors of manure and plant density was significant on the studied traits only for the second sampling stage. Lack of fit had no significant effect on the studied traits. The full square model for the response variables gave insignificant lack-of-fit indicating that the data were satisfactorily explained. In the first and the second cuttings, R2 ranges for biomass yield and biomass yield+ essential oil were 70.39-84.62% and 27.36-63.06%, respectively. The highest observed and predicted values of biomass yield were recorded in 12.5 plants.m-2+ 35 t.ha-1 cow manure (755.13 g.m-2) and 15 plants.m-2+ 35 t.ha-1 cow manure (319.92 g.m-2), respectively. The mean yield of biomass yield in the second cutting was higher than the first cutting. Optimum levels of plant density and cow manure and desirability for biomass yield were calculated with 10 plants.m-2+23 t.ha-1 and d= 0.94 and the parameters for biomass yield, and essential oil percentage were with 10 plants.m-2, 49 t.ha-1 and d= 0.96, respectively.

In general, it seems that resource use optimization using RSM may be suitable cropping approach for sustainable production of medicinal plants in agroecosystems.

Aloe vera is a permanent, evergreen species with special industrial and pharmaceutical applications. However, information about its nutrition management is scarce. Plants absorb nutrients through complex interactions in the rhizosphere between roots, symbiotic or non-symbiotic microorganisms and soil fauna. Inoculations of soil microorganisms (in the form of biofertilizers) to improve crop production and plant health were mainly undertaken for the group of bacteria known as PGPB (plant growth-promoting bacteria) or PGPR (plant growth-promoting rhizobacteria) and mycorrhizal fungi. To be effective, inoculated organisms must have soil conditions that are suitable for development, which can be improved by applying manure. Compared to the use of inorganic fertilizers, the application of organic manure in agriculture fields results in significant effects on microbial biomass, on the profile of existing species and, consequently, on the enzymes they circulate in the soil and its pool of organic matter. In this way, it interacts with the overall fertility of the environment. Different options of soil fertility management for increasing yield of aloe vera were studied in a field experiment.

A split plot experimentwas conducted based on randomized complete block design with three replications during 2012-2013 growing season in Agricultural Research Center of Bushehr province (29º16'0"N 51º31'0"E and 110 m above sea level). Seedlings were planted on May 4, 2012 with a distance of 0.7 m spacing on row with 1 m distance. The distance between Aloe vera rows was 1 m. The drip irrigation method was used for irrigation.  Main plot factor consisted of 0 and 20 ton.ha-1 sheep manure and five methods of soil fertility management were assigned to subplots including 1) chemical fertilizer (80 kg.ha-1 super phosphate+200 kg.ha-1 urea), 2) Mycorrhiza (using soil containing fungi from mosea), 3) biological fertilizer nitrogen (containing Azotobacter spp; Pseudomomas spp; and Azosprillium spp), 4) combination of Mycorrhiza and Nitrogen, and 5) no fertilizer (control). Monthly samplings were taken in 150, 180, 210, 240, 270 and 330 days after planting. Fresh and dry weight of leaves, leaf length, width and thickness and number of leaves per plant were measured. Harvestable leaves were considered as final yield.

The results indicated that interaction between manure and chemical or biological fertilizers was significant for all measured traits. Application of sheep manure was led to significantly higher growth and yield of aloe vera with better performance when manure was combined with chemical fertilizers. The highest number of leaves was obtained from integrated use of manure and chemical fertilizers with about 15 leaf per plant. While the lowest number of leaves was observed in control treatment. The interaction between treatments had a significant effect (p≤0.01) on leaf thickness. Plants treated with combination of chemical fertilizer and sheep manure had significant differences with other treatments, except with integrated use of biological fertilizers and manure. The highest fresh and dry weight of plant 3107.2 and 78.1 g plant-1, respectively and the highest final yield (36.04 tons.ha-1) was achieved with integrated use of manure and chemical fertilizers. The results also indicated that high aloe vera yields with great quality could be obtained with combined application of manure and biological fertilizers as an alternative for chemical fertilizers.

Producing medicinal plants under low input of chemical fertilizers is of great importance for human health, environment as well as production costs. Results of this experiment showed that application of manure with biofertilizers could be considered as a proper alternative to chemical fertilizers. Nutrition of aloe vera with this integrated management method will results to high yield and quality in addition to improving the physical, chemical and biological properties of soil.AcknowledgmentWe are grateful to Ebrahim Farrokhi and Kohzad Sartavi for their help with the field experiments, collecting field data and providing necessary advices to carry out this work.

Intercropping is highly recommended to be used in many parts of the world for food or fibers productions, because of its overall high productivity. Intercropping consists of growing two or more crops together at once, even though the crops are not sown or harvested simultaneously. The success of intercropping is due to an enhanced temporal and spatial complementarity of resource capture. Many studies have reported that intercropping can increase crop yield due to efficient utilization of nutrients and light, and enhanced positive interactions between crops. Features of an intercropping system can differ with soil conditions, climate, economic situation, and preferences of the local community. In this study, we carried out a two-year field experiments to evaluate yield and yield components as well as growth indices in cotton and maize grown in an alternative intercropping systems.

The experiment was carried out based on a randomized complete block design at Gonabad Agricultural and Natural Resources Research Station. The cotton (Khordad cv.) and maize (D.C 370) plants were evaluated using an alternative intercropping system. The treatments consisted of one row of cotton along with one row of maize, two rows of cotton along with one row of maize, three rows of cotton along with one row of corn, and pure cotton and maize cropping. The seeds were sown 20 cm apart in the rows in May. Irrigation was performed every 10 days and monitored using a volumetric flow meter. Twenty days after emergence, sampling was carried out by harvesting three plants of each species to measure growth indices such as plant height, leaf rea index and dry weight. At the end of growing season the crops were harvested and yield and yield components were determined. The data were analyzed by using SAS 9.1 software.

The effect of intercropping was significant on maize seed and forage yield. Since plant density in intercropping treatments was less than pure culture, the maximum maize seed and forage yields were obtained from pure culture treatment. By contrast, the minimum seed and forage yields were related to one row maize along with two rows cotton treatment. Reduction in maize biological yield due to intercropping was reported by Khorami-Vafa (2006), Tuna and Orak (2007) and Patel et al., (1999). Three rows cotton along with one row maize treatment produced the maximum maize seed and forage yields. Yield increasing in this treatment may be due to more space between maize plants, providing more light and reducing intraspecific competition. No significant difference was found between intercropping treatments in terms of cotton yield. The maximum cotton yield was obtained from cotton pure cropping, whereas, the minimum yield was related to one row cotton along with one row maize treatment. Amongst intercropping treatments, the maximum cotton yield was obtained from two rows cotton along with one row maize treatment. The increase in maize and cotton biomass followed a similar trend in both years. The maximum reproductive and vegetative branches, dry matter and leaf area index were related to two rows cotton along with one row maize treatment. The maximum maize leaf area was related to three rows cotton along with one row maize treatment. In general, dry matter accumulation linearly increased 30 days after seed sowing in both maize and cotton plants and reached to its maximum 60 days after seed sowing and then started to decrease due to leaf senescence and abscission. Furthermore, in both species, leaf area index reached to its maximum 69 days after seed sowing and then started to decrease due to canopy closure, shading, leaf senescence and abscission. Mukhala et al, (1999) and Koocheki et al, (2010) have shown intercropping cause a significant increase in leaf area index.

Generally it is concluded that maize and cotton yield in intercropping treatments were higher also traits such as leaf area index and dry matter accumulation in one row maize along with three row cotton was higher than other treatments.

The use of intercropping as an effective component in sustainable agriculture, while increasing the ecological and economic diversity, cause increasing yield per unit area, yield stability under adverse environmental conditions, increasing the quantity and quality of the product, increasing water use efficiency, control of soil erosion, reducing pesticides use and increasing stability in agroecosystems. Plants from the family of legumes are among the plants that have a special place in intercropping because of their nitrogen fixation ability. Usefulness of intercropping cultivation of sweet corn and green bean has been reported to be better than monoculture. This study was designed and conducted with the aim of studying the effect of replacement and additive intercropping green bean with bell pepper on yield, yield components and land equivalent ratio in Mashhad weather conditions. 

The experiment was conducted in 2015-2016 growing season based on a randomized complete block design with three replications at the Research Farm of Agriculture Faculty, Ferdowsi University of Mashhad. Experimental treatments were 25% green bean+75% bell pepper, 50% green bean+50% bell pepper in replacement intercropping, 20% green bean+100% bell pepper and 40% green bean+100% bell pepper in additive intercropping and monoculture of green bean and bell pepper. Green beans have planted by seed and bell pepper transplants were sown at the same time in June 2016 in rows with a distance of 50 cm. In 4-leaf stage, green bean was thinned with an optimum density of 20 plants per square meter. In addition, the spacing on the row was considered 30 cm for transplants of bell pepper; in this case, its optimum density was 6.66 plant per square meter. At harvest time, green pod yield for green bean, fruit yield for bell pepper, other yield components and plant dry weight for two plants were measured, and land equivalent ratios were also calculated.

The highest green pod yield and plant dry weight for green bean with 57921.7 and 1051.03 kg ha-1, respectively, was observed in monoculture and the lowest values for 20% green bean+100% bell pepper with 11252.5 and 525.8 kg per ha, respectively. With the increase in the presence of green bean in replacement and additive intercropping, the green pod yield of green bean increased due to increasing of biological nitrogen fixation. For bell pepper, the highest fruit yield with 32766.7 kg ha-1 was observed in monoculture and the highest plant dry weight with 7816.6 kg ha-1 was observed for 75% bell pepper+25% green bean and the lowest fruit yield was obtained for 50% bell pepper+50% green bean and 100% bell pepper+20% green bean with 21183.3 and 21886 kg ha-1, respectively, and the lowest plant dry weight was obtained for 50% bell pepper+50% green bean with 3533.33 kg ha-1. Due to the fact that the highest number of fruits per plant was observed in monoculture of bell pepper, therefore, monoculture has higher fruit yield because it has more space for plants. The highest value of total land equivalent ratio (1.28 and 1.25) was obtained in ratios of 40% green bean+100% bell pepper and 50% green bean+50% bell pepper, respectively, indicating 28 and 25% yield advantage of intercropping compared to pure stands of species of these two plants. The lowest value of total land equivalent ratio (0.86) was observed in ratio of 20% green bean+100% bell pepper.

Comparison of different patterns of replacement and additive intercropping showed that cultivation pattern of 25% green bean+75% bell pepper was superior for most of the traits evaluated in green bean and bell pepper compared to other patterns. Additive intercropping pattern of 40% green bean+100% bell pepper had the highest total land equivalent ratio (1.28) which indicate the beneficial effect of mixed cropping pattern over pure cropping. Since green bean through biological nitrogen fixation, leads to reduction in the use of chemical fertilizers, intercropping of this plant with other plants such as bell pepper can increase the resources efficiency and improve yield quantity for bell pepper.

Purple nutsedge (Cyperus rotundus L.) is one of the problematic weeds worldwide prevalent in tropical and subtropical regions. Tubers are major tools through which purple nutsedge is propagated, whereas its seeds have a low ability to germinate. Therefore, evaluation of the response of tubers against environmental agents is great of importance to know the germination and emergence time. Germination, in turn, is mostly affected by temperature, among other environmental factors. Various models that are recognized as the Thermal Time model have been introduced to describe the seed germination pattern against temperature. Since predicting the emergence of reproductive organs through the modeling is great of importance for improving the control strategies; the present study was carried out to investigate the response of tuber sprouting of purple nutsedge (Cyperus rotundus) against temperature using thermal time models.

The experiment was carried out as a randomized complete block design with three replications in a germinator. Each replicate was placed on a separate shelf. For each replicate, 15 tubers were placed inside a 20 cm Petri dish on a filter paper and then 100 ml of water was added. The experiment was performed separately for constant temperatures of 10, 15, 20, 25, 30, 35, and 40 °C in absolute darkness. To analyze the data as modeling, five thermal time models were evaluated based on the statistical distributions of normal, Weibull, Gumble, logistic and log logistic. Indices such as R2, RMSE, RMSE%, and AICc were used to evaluate the models.

The results showed that all models predicted the germination response of purple nutsedge tuber with high accuracy (R2 = 0.95). A comparison of models based on AICc values showed significant superiority of the Gumble model over other models. According to this index, there was no difference between logistic and log logistic models with normal. Among the models, Weibull was identified as the most inappropriate model. Different models estimated the final germination (Gmax) between 0.93 to 0.94 (93 to 94%). The base temperature was estimated through different models from 7.10 to 7.47 °C. Among the models, the model based on the Gumble distribution proved the skew to the right of the thermal time and Tm. According to the Gumble model, the thermal time parameters required to reach 50% germination (θT (50)) equals 123.8 ° C day and the maximum temperature for germination at 50% probability (Tc (50)) was estimated to be 46.10 ° C.

the thermal time model based on the Gumble probability distribution was most plausible among the models. Also, a distributed right skewness related to the thermal time and Tm was proved through the Gumble model. The parameters obtained from the Gumble model can be used to predict the sprouting of purple nutsedge tubers. 

Thermal time models were evaluated for prediction of tuber sprouting of purple nutsedge. The thermal time model based on the Gumble distribution was superior over the normal distribution. Thermal time and Tm for tuber sprouting of purple nutsedge were distributed as right skewness.

Carbon footprint (CF) is the total amount of greenhouse gas emissions per unit of farmlands. Since the used inputs have an important role in greenhouse gas emissions, CF as an ecological indicator have been extensively applied for assessing the environmental externalities in agroecosystems. This study was conducted to estimate the CF and carbon efficiency (CE) of saffron production systems in North Khorasan, Razavi Khorasan and South Khorasan provinces. Also, life cycle assessment analysis is calculated for quantifying the impact of saffron farming activity on the environment. Studied indices were global warming potential (GWP), acidification potential )AP) and eutrophication potential in terrestrial (UPT) and aquatic (UPA) sub-categories, N2Odirect, N2Oindirect, N2O emissions affected as volatilization and leaching, carbon inputs (Ci), carbon outputs (Co), CF and CE. The results revealed that the lowest GWP for saffron production systems was related to south Khorasan with 339.43 kg CO2 equiv./ one kg flower yield. The minimum environmental index (EcoX) was recorded for south Khorasan (0.039 EcoX/ one kg flower yield). N2O emissions in South Khorasan, Razavi Khorasan and North Khorasan provinces were estimated with 95974.51, 199674.4 and 344723 kg N2O per one ha, respectively. The largest N2O emissions affected as leaching and volatilization were calculated for North Khorasan province (with 1.21 and 24.23 kg N2O per one ha, respectively). The maximum Ci and Co were related to North Khorasan province with 117986.52 and 15135.56 kg C per one ha, respectively. The largest CF and CE were computed for North Khorasan and south Khorasan provinces with 7.8 and 0.18, respectively. It concluded that adoption on conservation and reduced tillages, N2- fixing pulses, cover crops and green manures in rotations with saffron and increased nitrogen use efficiency as ecological approaches can optimize the system performance while reducing environmental externalities and the carbon footprint of the crop cultivation. So, with relevant agro-environmental policies in saffron production systems along with the adoption of improved agronomical practices increasing flower yield with no cost the environment can be achieved effectively, efficiently and economically.

A prerequisite to model crop growth is an appropriate quantification of crop canopy structure in response to management and environmental conditions. Under water stress, the light distributions over canopy depth are more complicated because water stress affects not only appearance and elongation of leaves, but also morphological aspects of leaf positioning, leaf angle and azimuth angle (Archontoulis et al., 2011). Water stress reduces RUE by preventing effective photosynthesis for growth due to lower intercepted PAR as a result of reduced leaf area and leaf rolling or wilting (Wilson and Jamieson, 1985; Xianshi et al., 1998; Ngugi et al., 2013).We devised a two-year field experiment under different irrigation regimes at the two stage growths tomato with the aims of quantifying and describing the response of canopy light extinction coefficient, radiation use efficiencies, leaf area index and yield to reduced water at vegetative and reproductive stages of tomato in order to obtaining the best yield.

A field experiment was conducted over two consecutive seasons (2016-2017) in the experimental field of Ferdowsi University of Mashhad located in Khorasan Razavi province, North East of Iran. The experiment was laid out in a split plot design with different irrigation regimes at the reproductive and at the vegetative stage as the main and subplot factors, replicated thrice. The following experimental factors were studied: three irrigation regimes (100= 100% of water requirement, 75= 75% of water requirement, 50= 50% of water requirement) and two crop growth stages (V= vegetative stage and R= Reproductive stage). The drip irrigation method was used for irrigation. The tomato water requirement was calculated using CROPWAT 8.0 software. The irrigation water was supplied based on total gross irrigation and obtained irrigation schedule of CROPWAT. In the both growing seasons, plant growth and physiological parameters were assessed in two weekly intervals on two plants per plot starting 45 days after transplanting (DAT) up to 145 DAT.

Leaf area index (LAI) of tomato varied between irrigation regimes. According to ANOVA, the treatments had a significant effect on maximum LAI in both years (Table 5).The fraction of PAR intercepted by tomato canopy, measured in two years of study, increased from a few days after transplanting (May) onwards, reaching its maximum value in mid-August (around 100 DAT) in all treatments and later on decreased with progress of season till final measurement except 75V-100R and 50V-100R where the fraction of intercepted PAR raised up to the end of growing season (Fig. 5).As shown in Fig. 4, with increasing LAI, the transmitted fraction of radiation through the canopy decreased exponentially in all treatments. The highest and lowest k value was recorded by full irrigation treatment with 0.69 and 50V-50R treatment with 0.41, respectively. k values were strongly variable among different irrigation regimes.RUE altered according to amount of water applied at different growth stages. In this research, RUE values ranged from 0.38 to 0.9 g MJ-1. However, applying irrigation during vegetative stages could accelerate increase in leaf area, light interception and photosynthesis (Comas et al., 2019) and, thus, improve RUE.Timing of water stress had a significant effect (p < 0.01) on total fresh and dry fruit yield in both years of the experiment (Table 6). In general, tomato yield increased as the amount of irrigation water increased, however it was severely affected by timing applied irrigation. In 2016 and 2017 total fresh fruit approached 99.81 and 101.01 t ha-1 under full irrigation (100V-100R), significantly greater than that produced under full deficit irrigation (50V-50R) with 22.2 and 15.66 t ha-1, respectively (Fig. 7).

The experiment results clearly indicate adverse effect of water shortage on tomato yield, so that the highest fresh yield was obtained with full irrigation. However, the results suggest that this adverse effect can be reduced by a proper irrigation management at different growth stages. We showed that the effect of water provided at sensitive growth stage on the productivity of tomato was largely due to the positive effect of water apply on RUE.

Intercropping is a well-known agro-ecological practice for its dramatic effect on pest and weed control, increasing productivity as well as enhancing resources (radiation, water and nitrogen) use efficiency. All these beneficial effects are the results of increased species diversity which presumably would be higher with introducing more component species. On the other hand, crop growth analysis provides indices for quantifying the rate of dry matter production and allocation of dry matter to the other organs, particularly to leaves. It seems that growth indices of intercropped species relative to their pure stands could be useful for better understanding of higher productivity of more diverse intercrops.The objective of this study was comparison of growth indices and dry matter allocation as well as land equivalent ratio of fennel (Foeniculum vulgar), common bean (Phaseolus vulgaris) and sesame (Sesamum indicum) grown in monoculture or intercropping systems. 

The experiment was conducted as randomized complete block design with three replications and seven treatments including pure fennel (F), pure sesame (S), pure bean (B), row intercropping with 1:1 ratio of FB, SB and FS as well as 1:1:1 intercrop of FSB. All treatments were sown in recommended planting date and density. Total aboveground materials of each plot were sampled in 5 randomly selected plants in two-weekly intervals and repeated seven times during growth period. Green leaf area index (GAI) and total aboveground dry matter (DM) were measured for each species in sole and intercropped plots. Time course of LAI and DM was estimated by fitting logistic peak and sigmoid functions to the measured values for each species, respectively. Crop growth rate (CGR; g m-2 d-1) of each species was estimated as the first derivative of the sigmoid function. Economic yield of species was measured by harvesting the whole plots and used for calculation of land equivalent ratio (LER) for intercropping treatments. 

Results showed that for all studied species, the growth indices were lower in intercropping compared to monoculture. Maximum GAI (1.28), dry matter (184.6 g.m2) and crop growth rate (5.2 g.m-2.day-1) for fennel was observed in pure stand. For sesame, the highest GAI (4.2) was obtained in the sesame – fennel intercrop, however, maximum dry matter (1023 g.m-2) and crop growth rate (24.5 g.m-2.day-1) were achieved in the pure stand of sesame. Similarly in bean, maximum GAI (3.8), dry matter (546.39 g m-2) and crop growth rate were observed in pure stand. However, the lowest GAI (0.61), dry matter (54 g m-2) and crop growth rate (1.6 g m-2 day-1) of fennel was observed in fennel-sesame and fennel-sesame–bean intercrops, respectively. The minimum GAI (3.24), dry matter (286 g.m-2) and crop growth rate (6.6 g.m-2.day-1) of sesame was obtained in fennel- sesame- bean, fennel- sesame and fennel- sesame- bean, respectively. The minimum LAI (3.08), dry matter (110 g.m-2) and crop growth rate (3.26 g m-2day-1) of sesame was observed in fennel- sesame- bean treatment. Despite the lower growth indices, LER was grater that 1 in all intercrops with a highest value (1.09) in sesame – bean showing the better allocation of dry matter between component species of intercropping. 

While the LAI, DM and CGR was lower when species were intercropped, the overall rate of dry matter production of intercropping systems was about 28%, on average, higher as compared with pure stands leading to almost 10% higher productivity. Addition of the third species into intercrops has no significant effect on productivity. However, it seems that using species with diverse functional traits to increase functional diversity could cause higher productivity of intercropping systems.

Sustainable development of saffron production as one of the major and strategic goals of Iranian agriculture requires a well-defined and organized plan. Over the past half century saffron cultivation has increased 34-fold in Iran, more than any other crop. But the average yield did not follow this development and is reducing with slight negative slope; so, the average saffron production in Iran has reduced from 5.76 kg/ha in 1973 to 3.42 kg/ha in 2017. It is also estimated that there is a 90-70% yield gap in Iranian saffron farms. Saffron pests and diseases such as saffron mite (Rhizoglyphus robini), saffron corm rot, saffron dry rot (Burkholderia gladioli) and saffron viral diseases are also responsible for quantitative and qualitative reduction of saffron yields in farms. Saffron is propagated by its daughter corms, so increasing the yield of saffron is directly related to the quality of mother corm seed. This paper describes the criteria’s needs to generate and certify prebasic, mother corm and seed corm classes of saffron for standard saffron corm schedule. Production of standard pathogen-free seed corms as the only means of saffron propagation in nature is a prerequisite for any planning to increase saffron yield. Undoubtedly, application of standard free pathogen corms along with other ecological and physiological indices of saffron plant will increase yield and improve Sustainable development indicators.

Natural and semi-natural features including those as patches and marginal elements, construct a network of habitats referred to as green vein elements. In the green veining, the linear elements connect the different parts of the network, while the patches have a role as nodes within the network. These networks potentially place a vast range of biodiversity and play an important role as a refuge for sensitive organisms as well as some habitat specialist species. With regards to crop production and pest management in agricultural fields, pollinators and biological control agents, like predators, are among the most beneficial organisms mostly found in green vein elements. As the biodiversity in agroecosystems is considerably declining, this study was conducted to address the important role of natural and semi-natural elements of the landscape in biodiversity conservation.
 

The study area was an agricultural landscape located in Gilane-Gharb County, Kermanshah Province, Iran with a Mediterranean climate. The level of agricultural intensification (AI) was surveyed through interviewing the farmers and considering the indicators such as chemical and organic fertilizers (Kg N/ha/year), pesticide input (utilization frequency of e.g. herbicides, insecticides and fungicides) and the number of tillage operations and mechanical weed control. by providing the geographic map of the area and frequent field observation, seven different types of patches and marginal habitats were identified, including: 1) arable and horticultural fields (Fi); linear elements adjacent to the fields including: 2) within field edges (W.F.E) and 3) non-crop field edges (N.F.E); 4) roads; ditches including 5) permanent ditches (P.D) , 6) non-permanent ditches (N.P.D) , and 7) woody greenvein (W.Gr) element. 87 sample plots (2 m × 2 m) were recorded in all the elements. Vegetation data from fields were recorded using 18 sample plots; woody green vein 19 sample plots; and other marginal habitats including within field edges, non-crop field edges, permanent ditches, non-permanent ditches and roads, were sampled by 50 plots. Sampling was done based on systematic-randomized method. Two emergent groups of plant species were introduced regarding their response to land use intensification: Agrotolerant and Nature-value species.The calculated biodiversity indices were: Jackknife species richness, Shannon-wiener, Simpson and Brillion diversity indices, Camargo and Smith-Wilson Evenness, and finally Sorenson Similarity index using Ecological Methodology software.

The calculated agricultural intensification index (AI) was 49.56; this score was at the range of high intensified agricultural utilization (High AI). Mean observed value of nitrogen input was 211.36 kg/ha, the weighted frequency of tillage operations and pesticide application per hectare was the same as 2.36. Apart from crop species, a total of 87 vascular plants were recorded in the agricultural landscape. The highest species richness was for agricultural fields (43 species), which followed by non-crop field edges (37), woody greenveins (32), within field edges (30), permanent ditches (26), non-permanent ditches (23) and roads (22). Sorghum halepense (L.) Pers.  (46.56% of the total frequency of individuals existing in the field sample plots) was the most frequent species in the landscape. 21 species were recorded as agrotolerant species. Jackknife species richness was 48.7 in the fields as the most, and 23.8 in the road verges as the minimum. Woody Green veins (W.Gr) had the most number of unique species. The most Shannon-wiener and Brillion diversity indices were recorded for agrotolerant and nature-value species in within field edges (Shannon-wiener: 2.03 and Brillion: 1.85) and fields (2.52 and 3.08) respectively. Sorenson similarity index revealed that the elements inhabiting high number of agrotolerant species had a similar spatial condition especially regarding being adjacent to the agricultural fields. Studies reported the outstanding benefits of greenvein elements in promoting plant biodiversity and as a result enhancing diversity of organisms which inhabit in such elements.

The study indicated the effect of agricultural intensification and types of land use throughout the landscape on biodiversity. Elements with high connectivity to natural or seminatural habitats had the most positive effect on biodiversity of plant spesies. To gain the targets of sustainability in agroecosystems, providing as much as possible natural and semi-natural habitats and corridors are suggested.

Tubers are considered as the most important vegetative organs in reproduction of purple nutsedge, as one of the most troublesome weeds worldwide. Therefore, it is great of importance to investigate the properties of the tuber response to the surrounding environment such as absorption and loss of water. Water uptake is the first step in the sprouting process, though the pattern of water uptake by purple nutsedge tubers has not been documented. Loss of water in tubers is one of the potent factors in reducing their ability to sprouting. Three separate experiments were carried out to investigate the absorption and loss of water content of purple nutsedge tubers.

In the first experiment, the tubers were placed in a water bath at temperatures of 10, 20, 30, and 40 ° C. Then, the weight of the tubers was measured at different times (24 till 3600 minutes). The water uptake percentage of tubers at different temperatures was studied by fitting the Peleg model. In the second experiment, the initiation day of sprouting was investigated at constant temperatures of 10, 20, 30, and 40 ° C. In the third experiment, water loss and sprouting percentage of tubers were evaluated in two conditions refrigerator (4° C) and room (22 to 25 ° C).

The results showed that the initial water content of tubers was 42% and absorbed 10% extra water after being immersed in water. The water uptake behavior was based on the Peleg model at two stages: (1) rapid uptake (less than 420 minutes (7 hours), and (2) a low uptake with a gentle slope afterward. In the Peleg model, the parameters K1 (minutes *.%weight -1) and K2 (%-1) are water absorption rate and water absorption capacity, respectively. The K1 parameter was negatively against temperature. The highest and lowest values were 49.56 and 28.55 at 10 and 40 ° C, respectively. On the other hand, the trend of the K2 was constant (0.1) at 10-30 °C but was 0.08 at 40 °C. The two-parameter Hyperbola model was superior to the Peleg and predicts the highest water absorption and time to 50 percent water absorption parameters. The results showed that sprouting of purple nutsedge tubers at 10, 20, 30, and 40 °C occurred after 14.44, 6.57, 3.24, and 3.12 days, respectively. Keeping the tubers in the room (22-25 °C) and refrigerator (4 °C), sprouting stopped after 3 and 9 months, respectively. The time required for 50% reduction of sprouting in the room and refrigerator was estimated to be 1.3 months (39 days) and 5.12 months (154 days), respectively. The time required for 50% loss weight of tubers in the room and refrigerator was 1.981 months (59 days) and about 6 months (180 days), respectively. Overall, weight loss (water loss) up 11.85%, resulted in 50% reduction in tuber sprouting.

Maximum water uptake in tubers occurred in less than 420 minutes (seven hours) at all temperatures. Slow sprouting in tubers at low temperatures is not associated with an obstacle in water absorption. Tubers lost half of their sprouting ability by losing water about 12%. On the other hand, the results show that the tubers at cool temperatures (4 °C) lose their water and sprouting capacity less than the ambient temperature (22 to 25 °C).

Introduction:

Water and plant density have a complex interaction. Determination of optimum density is an effective strategy to improve the efficiency of available resources usage and to increase the yield per unit area. Despite extensive research on the effects of different levels of irrigation and plant density for different crops, including corn, information on the optimization of these resources, using response-surface methodology (RSM) is scarce. Therefore, the objective of this study was to determine the optimal level of irrigation and plant density in corn production based on central composite design (CCD).

 An experiment was conducted by using response-surface methodology with the central composite design and two replications on corn at the Research Farm of Ferdowsi University of Mashhad, during the 2015 growing season. The experimental treatments were the highest and lowest levels of irrigation volume (6000 and 14000 m-3.ha-1) and plant density (5 and 9 plants.m-2). Grain yield (GY), biological yield (BY) and water use efficiency (WUE) were measured as response variables in a full quadratic polynomial model. Consumption rate of irrigation and density were optimized based on three scenarios: economic, environmental and eco-environmental. Grain yield of corn and WUE were considered as the main factors to determine the optimum level of treatments under the economical and environmental scenarios, respectively. In the eco-environmental scenario, the main factor was WUE and grain yield.

The results indicated that at low level of irrigation (6000 m3.ha-1) plant density and grain yield correlated with others as quadratic so that by increasing the density from 5 to 7 plants.m-2,grain yield first increased and then decreased with enhancing density to 9 plants.m-2.It seems that at low levels of irrigation, reduction and enhancement of plant density, respectively, as a result of increasing evaporation from soil surface and increasing competition in resource uptake (light and water) has reduced grain yield. Grain yield at high levels of irrigation showed a relatively linear relationship with incrementing plant density, and the highest grain yield with 1324.9 g.m-2was obtained from treatment of 14000 m3.ha-1 of water and density of 9 plants.m-2. Nevertheless, the results of model fitting showed that the highest grain yield with 1318.4 g.m-2 was attained from the density of 7 plants.m-2 and 14000 m3.ha-1 of water. Therefore, it seems that with the simultaneous enhancement in plant density and irrigation, vegetative growth due to lack of light has increased, as a result of grain yield than optimum densities (7 plants.m-2) has shown a decrease.The regression model could significantly indicate that impact of independent variables on the grain yield, biological yield and water use efficiency (dependent variable). In economic scenario with considering 8 plants.m-2 and irrigation of 14000 m3.ha-1 the maximum of economical yield with 1345.8 g.m-2 was achieved in which biological yield and water use efficiency were 4534.7 gr.m-2 and 0.98 kg.m-3 of water, respectively. In environmental scenario also the choice of the density of 7 plants.m-2 and irrigation of 7939 m3.ha-1 the highest water use efficiency (1.21 kg.m-3) was attained in which grain yield that was 988.6 g.m-2. Based on eco-environmental scenario with choice of the density of 7.5 plants.m-2 and irrigation of 10848.5 m3.ha-1 the maximum grain yield and water use efficiency was obtained in 1240.7 g.m-2 and 1.16 kg.m-3 of water, respectively.

Due to lack of water resources and environmental problems caused by the excessive use of water, applying appropriate management practices such as proper planting density to optimize these resources is essential. The best way to achieve the highest economic yield and water use efficiency and, to reach sustainable agriculture is the choice of eco-environmental scenario in which by application of the density of 7.5 plants.m-2 and irrigation level of 10848.5 m3.ha-1 the maximum grain yield and water use efficiency with 1240.7 g.m-2 and 1.16 kg.m-3 of water was obtained, respectively.

Crop models can integrate the complex interactions of soil properties, climatic conditions, crop management practices, and crop genetic characteristics. One of the main aspects of crop simulation models is the possibility to use them across various environmental and management conditions, provided that they have been evaluated under a wide range of growing conditions. The Decision Support System for Agrotechnology Transfer (DSSAT) modeling platform is leading crop modeling system that is widely applied in various environments. Testing crop models under various temperature environments are essential to apply models to climate impact studies. The objective of this study was the testing and evaluation of DSSAT-Nwheat model across a wide range of climate conditions in Iran.

Nwheat model, which recently integrated into DSSAT, was evaluated for four wheat cultivars using observations from field experiments included a wide range of climate and management. Cultivars were Shahriyar, Pishtaz, Tajan, and Chamran cultivated in cold, temperate, humid and tropical regions in Iran, respectively. The locations represent four different wheat mega-environments, a concept used by wheat breeders for testing cultivars. The management information used at each site was obtained from the Seed and Plant Improvement Institute. Daily weather data, management events, and soil characteristics imported to DSSAT. The performance of the DSSAT-Nwheat during the calibration and evaluation was assessed using different statistics, Root Mean Square Error (RMSE), Normalized Root Mean Square Error (nRMSE), Willmott’s index (d), and coefficient of determination (R2) of a 1:1 regression line. A sensitivity analysis was conducted using 30 years of observed weather data from Tabriz, Mashhad, Gorgan, and Ahwaz. For the sensitivity analysis scenarios, the temperaturewas increased by 3, 6, and 9°C, and atmospheric CO2 concentration levels were set at 360, 540, and 720 ppm.

Evaluation results showed that DSSAT-Nwheat model simulated planting to anthesis and planting to maturity accurately with RMSE values less than four days, nRMSE less than 3%, and d index close to one. Also, evaluation of grain yield showed that RMSE varied from 568 kg ha-1 for Tajan cultivar up to 933 kg ha-1 for Chamran cultivar. In general, nRMSE and d index for grain yield were less than 20% and higher than 0.8, respectively, which showed good calibration accuracy. In DSSAT-Nwheat model, the specific heat stress function explains heat stress effects during grain filling on grain yield in cultivars. Chamran cultivar is somewhat resistant to end season heat stress, so the DSSAT-Nwheat model underestimated in the warm regions. Because the cultivars differ regarding resistance to the end season heat stress, crop models need to consider cultivar-specific tolerance to heat stress to better simulate temperature effects on wheat cropping systems. The response of the model to the increase in temperature was different in regions and levels of CO2 concentrations. Elevated atmospheric CO2 concentrations lessened some of the adverse effects of high temperature. Therefore, the sensitivity analysis of DSSAT-Nwheat model to temperature variations and elevated atmospheric CO2 concentrations showed that the model could be used in studies of climate change impacts on wheat production. This model can be employed to explore the integrated effects of temperature, atmospheric CO2concentrations, water, nutrients, and agronomic management practices in a range of wheat growing environments.

The results of this study showed that the DSSAT-Nwheat model had reliably good performance under a wide range of management and environmental conditions. This calibrated model can now be used for assessing impacts of various agronomic management strategies and decisions in wheat cropping systems under current and anticipated climate change. But more importantly is the calibration method and using a large number of climatological data to calibrate.

Response surface methodology (RSM) is defined as statistical technique for optimization of multiple parameters which determine optimum process conditions by combining experimental treatments (5,10,11). In this work, optimization of N and P fertilizers on yield, yield components and seed quality of wheat using RSM were studied.

An experiment was conducted with 13 treatments and two replications at the Research Field of Ferdowsi University of Mashhad during the growing season of 2015-2016. The treatments were allocated based on low and high levels of N fertilizer (0 and 400 kg Urea per ha, respectively) and P fertilizer (0 and 100 kg triple super phosphate per ha, respectively). Biological yield, seed yield, harvest index, growth criteria and yield components (such as tiller No./m2, plant height, spike length, seed No./ spike, seed weight/ spike, seed weight/ plant, spike No./ plant, spike weight/ plant and dry weight of stem per m2) and seed quality characteristics (including N percentage, protein percentage and P percentage) were calculated as dependent variables and changes of these variables were evaluated by a regression model. Lack-of-fit test was used to evaluate the quality of the fitted model. The adequacy of the model was tested by analysis of variance. The quality of the fitted model was judged using the determination coefficient (R2). Finally, the optimum levels of N and P fertilizers were calculated based on three scenarios including economic, ecological and economic-ecological.

The results showed that effect of linear component was significant on harvest index, spike length, yield components (such as seed weight per plant, spike No./plant, spike weight per plant and tiller No./m2), N percent and protein percent of seed. Effect of square component was significant on biological yield, seed yield, tiller No./m2, seed weight per plant and spike weight per plant, N percent, protein percent and P percent of seed. Interaction effect of full quadratic was significant on plant height, spike length and seed No./spike and N percent of seed. Lack of fit test had no significant effect on the studied traits. The full square model for the response variables gave insignificant lack-of-fit indicating that the data of experimental were satisfactorily explained. The highest observed and predicted values of seed yield were recorded for 400 kg Urea per ha+100 kg triple super phosphate per ha and 200 kg Urea per ha+50 kg triple super phosphate per ha with 717.54 and 594.89 kg.ha-1, respectively. The maximum observed and predicted amounts of seed N percent (with 1.72 and 1.62 percent, respectively) and seed protein percentage (with 10.76 and 10.02percent, respectively) were recorded for 400 kg Urea per ha+50 kg triple super phosphate per ha. Both seed yield and N and P percent of seed were considered in economic-ecological scenario, so the estimated levels for N and P fertilizers were 141.41 kg Urea.ha-1 and without P fertilizer.

Increasing rates of N and P fertilizers up to optimum rates increased yield and seed quality of wheat. Nutrient optimization enhances nutrient absorption and yield in the wheat cropping systems may reduce the dependence on external sources of chemical fertilizers that increase the costs of production and can potentially contribute to environmental contamination. The optimization of soil nutrients provides information on the sustainability of cropping systems and potential environmental pollutions. Generally, nutrient optimization is a useful technique widely used in modern agriculture.

This study was carried out to evaluate the cardinal temperatures of germination of three Amaranth species (Amaranthus retrouflexus L.), (Amaranthus viridis L). and (Amaranthus blitoides S. Watson). The experiment was conducted as a completely randomized design with nine temperatures (5, 10, 15, 20, 25, 30, 35, 40 and 45) and four replications at Weed Science Research Laboratory of Ferdowsi University of Mashhad. Sseed germination percentage and rate was calculated and regression models were used to evaluate the results and determine cardinal temperatures. Based on the results, among the nonlinear regression models, the intersected lines and quadratic polynomial models with respect to the highest coefficient of determination (R2) showed the best fitting of germination rate of seeds. Accordingly, the intersected lines model was more preferred. generally over the minimum temperature, optimum temperature and maximum temperature using intersected-lines model for green pigweed of 4.86, 25.56 and 45.76 ° C, respectively. Red root pigweed was calculated 6.65, 30.56 and 51.6 ° C, respectively, and was estimated to be 9.22, 34.39 and 50.66 ° C for prostrate pigweed, respectively. The results of this study showed that sow seed germination was carried out over a wide range. All three species were able to germinate between 10 and 45 ° C.

Climatic variation particularly for participation is a constraint for the crops to reach their potential productivity under rainfed conditions. Therefore soil moisture preservation by means of tillage practices and improvement of soil physical criteria, particularly through enhancement of organic matter content is crucial. For this reason soil tillage must be managed in a proper way in order to fulfill this objective. Use of the right implements for this purpose under rainfed conditions together with retention of crop residue are practices most suitable for low rainfall environments. Tillage operation has a great impact on soil properties such as soil particle stability, soil aggregate and also soil water holding capacity. There are good evidences regarding yield improvement under rainfed conditions when implements such as chisel plow and sweep plow is used. Reduced tillage has been referred to as a proper practice under such conditions and degrees of no to minimum tillage have been proposed. These types of tillage combined with retention of crop residue which is referred to as conservation agriculture is being received more attention for the sake of soil conservation and moisture preservation. The purpose of the present study was to investigate these type of management for a rainfed wheat-fallow rotation.

In order to study the effect of different tillage practices in fallow-wheat rotation and retention of crop residue on soil properties such as bulk density, soil aggregate, porosity, particle stability and moisture holding capacity and also crop criteria including yield, above ground biomass of wheat and weed under rainfed conditions, an experiment was conducted for two years (2013-2014 and 2014-2015 growing seasons) in Shirvan region, Northeast of Iran. The layout of experiment was strip plots based on a randomized complete block design and three replications. Tillage systems and retention of crop residue were the experimental factors with four levels of tillage (chisel, sweep, moldboard and no tillage) and three levels of crop residue retention (7, 3.5 t.ha-1 and zero residue). Tisdal and Oades method used to determine the soil aggregates size distribution in dry and wet sieving conditions. To determine the soil bulk density, undisturbed samples were picked up from a depth of 0-10, and 10-20 cm and soil bulk density were determined after drying of soil in Oven for 48 hours at a temperature of 105°c. In order to evaluate the soil moisture at the end of the fallow year, sampling was done from each treatment in the depth of 0-20cm. During growth and after harvesting, the plant height, ear length, seed number per ear, thousand kernel weight, seed yield, and biological yield were determined.

Results showed that in general soil bulk density was higher at the depth of 0 to 10 cm compared with that at the depth of 0 to 10 cm for the experimental soil. Soil porosity followed a reserve trend of that of bulk density. Retention of crop residue caused a slower bulk density and a higher soil moisture content. Tillage with moldboard at different levels of crop residue retention caused lower weed biomass compared with other tillage operation. Soil practices size higher than 0.5 mm were respectively higher and lower with moldboard plow. Seed yield and also above ground biomass were higher with moldboard plow compared with the conservation tillage practices. Despite lots of reports about the prominence of conservation tillage systems in comparison with moldboard tillage, the reason for the prominence of moldboard plow in comparison with conservation tillage in this experiment can be attributed to better seedbed preparation in moldboard tillage. The other reason for seed yield increment in the treatment of moldboard tillage in comparison with other treatments can be the effective control of weed plants, especially Russian Knapweed.

Despite contradictory reports about the effect of moldboard tillage on wheat yield in comparison with conservation tillage, the results of this experiment showed the prominence of moldboard tillage in contrast with the sweep, chisel, and no-tillage for wheat production. Under rainfer conditions retention of crop residue together with minimum level of soil disturbance seems to be a proper practice. This has been evidenced elsewhere and is confirmed somehow in our experiment too. This is mostly related to enhancement of water holding capacity of the soil.

Biodiversity as a key factor of sustainability of natural ecosystems have been largely used in studies on natural vegetations (e.g. rangelands) at different spatial scales. Baharkish pasture with area of 1035 hectare is situated in 60 km distance southern of the city Quchan in Khorasan Razavi province. The lowest and the highest altitudes of the pasture are 1740 and 2440 meters a.s.l., respectively. Long-term (25-year) mean annual precipitation and temperature of the region is 337 mm and 9.4°C with 998.2 mm evaporation. In this study, about 200 hectares of Baharkish pasture with moderate grazing pressure was chosen by the clipping and weighing method to study the effects of environmental factors of plant species richness and diversity.

In order to evaluate the effect of ecological factors on the biodiversity of plant species in Quchan Baharkish pasture, at first all topographic maps (1:25,000), geological maps (1:100,000), aerial photos (1:20000) and satellite images of Quchan Baharkish were collected. Then, maps of altitude classes, slope, aspect and geological formations were prepared and merged by overlapping in ArcGIS 10.2. The generated maps were coded and 13 homogenous working units and their maps were prepared for further studies, field visits and pasture vegetation measurements. Finally,  four homogeneous vegetation types were determined for sampling based on the structure, distribution, and presence of dominant species. Hence, in each vegetation type 35 plots (2m2 each) were systematic-randomly selected and used for composite soil sampling (0-30 cm depth) and estimation of  vegetation indices. The species number and percentage of canopy cover were estimated in each plot and the plot locations were recorded with GPS devices in U.T.M system.Plant species diversity per plot was estimated using Shannon-Wiener and Simpson diversity indices, richness index of Margalef and evenness index of Smith-Wilson in Ecological Methodology software. One-way ANOVA was used to examine the components of biodiversity and Tukey test was performed for multiple mean comparisons. Principal component analysis (PCA) was conducted to classify vegetation types and to determine the contribution of ecological factors on biodiversity of the studies pasture.

The results indicated that altitude had significant effect on species diversity, richness and evenness and the highest values of Simpson and Shannon indices were obtained at 1900-2200 m a.s.l. Indirect effect of soil formation and direct influence of temperature were led to variation in distribution of plant species and rangeland community structure. Amount and type of precipitation and consequently vegetation type was changed with altitude. Species richness and diversity was significantly affected by slope, and lower slopes (<15%) showed the highest values of richness and diversity index. However, evenness was higher in 15- 45% slopes. Overall, northern slopes had significantly higher species diversity, suggesting that plant available water is drastically influenced by slope through infiltration rate and land index. Results of PCA indicated that the first PC containing soil organic carbon, sand content and slope had the highest effect on species diversity.

In general, it can be concluded that plant biodiversity in natural ecosystems was affected by topographic and edaphic factors particularly in high altitudes. The results of PCA showed that the PC1 including percentage of soil organic carbon, organic matter and clay and PC2 including electrical conductivity and elevation, percentage of soil moisture, silt, sand and slope had the greatest impact on species diversity. In addition, getting insight in to the relationship between diversity and ecological, topographic and edaphic factors can be proposed as an ecological approach for sustainable rangeland management.