In recent decades Climate and its changes have become one of the world major issues and as one of the major environmental problems. Agricultural sector is one of the first areas affected by these changes because farmers are not able to control climatic conditions; however, management and change in factors such as crop cultivar and optimization of the cultivation pattern according to area climate can reduce the adverse effects on growth and yield of agricultural products and play a significant role in the sustainable production of foods. Therefore, in this research, the effects of climate change on cropping pattern in Mashhad have been investigated. The statistics and data needed for the research were collected through Mashhad Agriculture Jihad Organization, meteorology Organization, as well as in-person interviews with agriculture specialists and farmers in Mashhad. The results of this study show that rainfall level, maximum and minimum seasonal temperatures have increasing trend and these changes have a significant effect on the yield of crops in the region. Also, considering the climate change scenarios (to 2031) during the planting period of each studied product, their crop area values have been changed and farmers' gross margin increased by 1. 6 percent compared to the base year (2014). Finally, the results of this study indicate that the greatest changes in yield due to climatic conditions are related to wheat and barley; therefore, it is necessary for policy makers to pay attention to this issue in order to reduce the risk of these products production and prevent from reduced production of these strategic crops.

Projected global climate change may have a major influence on crop yield. The likely effects of climate change caused by increasing atmospheric carbon dioxide levels on rice yield in Iran were evaluated using a mechanistic growth model for rice, GSAC-rice, running under a climate change scenario predicted for a doubled-CO2 (2xCO2) atmosphere by the Geophysical Fluid Dynamics Laboratory (GFDL) General Circulation Model (GCM). Simulations were run for two locations with contrasting climates, one in the north (Rasht) and one in the south (Ahwaz) of Iran. GFDL predicted that as a result of doubling CO2, temperature increases by 4.5 and 4.6 oC during the rice growing season in Rasht and Ahwaz, respectively. Changes in solar radiation are minor, but rainfall during the rice growing season decreases by 38.8% (102 mm) for Rasht and 68.2% (5.8 mm) for Ahwaz. It was predicted that doubling [CO2] alone increased rice yield by 30%, but that yield decreases by 3.7 and 11.6% for each degree centigrade rise in temperature in Rasht and Ahwaz, respectively. As a result of the combined effect of both doubling [CO2] and the climate change accompanying it (predicted with GFDL), 8% greater rice could be produced in Rasht, but irrigation needs would be increased dramatically by 57%. In Ahwaz (the south of Iran), rice production could be halved and might not even remain a viable option unless plant breeders are able to produce more heat tolerant rice cultivars. It was concluded that rice production in the north and south of the country would change dramatically.

Statistical detection is a method to reveal significant changes that cannot be attributed to natural variations. The agricultural sector heavily relies on climatic parameters such as temperature and precipitation, thus demonstrating a higher degree of responsiveness to climate change with increased intensity and speed. Climate change can also influence the cropping patterns and agriculture of a region over a long period. To enhance the quantity and quality of agricultural production in Golestan Province, it is necessary to study the climatic background and precipitation and temperature regimes over a long period (at least 25 years) to examine the trend of changes. Therefore, the Mondal and Papadakis methods were utilized on statistical data from meteorological stations in the province to obtain suitable winter and summer cropping types for Golestan Province. The climatic data used in this research includes monthly average minimum, maximum, and mean temperatures, monthly average absolute minimum and maximum temperatures, and annual average temperature and precipitation from 9 meteorological stations in Golestan Province within the time range of 1990-2018, obtained from the National Meteorological Organization. The results of statistical analysis showed no significant changes in the cropping pattern of the region during the study period (1990-2017), which can be justified by the defined temperature thresholds of the Papadakis model. For instance, the dominant winter cropping pattern was dual-headed barley, which requires the average maximum temperature of the coldest month to be above 10 degrees Celsius, a threshold observed in the region during the statistical period, thus indicating the continued cultivation of this crop in the future. Additionally, the prevalence of maximum temperatures above 20 and 25 degrees Celsius in the region and the prolonged absence of frost during the season are reasons for the stability of dominant summer cropping types in this province.

This study was conducted during summer and winter of 2018- 2019 in the agricultural research field of Shahid Chamran University. Experimental design was split- plot based on RCBD with three replications. The main plot was the type of agricultural system in three levels including conventional (Conv), organic (Org) and sustainable (Sust) (integrated between Conv and Org) and sup- plot was the type of pre- cultivated crop in sequence with wheat including cultivation of mung bean (M- W), corn (C- W), sesame (S- W) and fallow (F- W). Yield quantity (yield and its component) and quality (grain protein), an estimate of photosynthesis matter transfer index of wheat and soil organic carbon (SOC) after one double-cropping were measured. The result showed that the highest (545.04 g/m2) and the lowest (409.28 g/m2) seed yields were obtained in Conv and Org respectively. In contract, with the changing type of system from Conv to Org, grain protein was increased significantly (from 8.3 to 9.6 %). In addition, the highest (535.47 g/m2) yield of wheat was obtained from M- W double cropping. On the other hands the highest remobilization and current photosynthesis matter were obtained in the organic agricultural system with M- W and conventional with M- W double cropping. The situation of SOC showed that the highest (33.18 mg/g) SOC was obtained in the organic agricultural system with C- W double cropping. The reason for improving SOC in the organic and sustainable agricultural system was application of organic matter (compost and vermicompost) and crop residue management. Totally, from the crop ecology point of view, sustainable agricultural method with a sequence of M- W was the most desirable system.

Introduction: Considering that the agricultural sector is strongly dependent on climate parameters of temperature and precipitation, it reacts rapidly related to climate change. Farmers are not able to control the climatic conditions, but management and optimization of the cropping pattern according to the region's climate can reduce the effects of climate change on the yield of agricultural products. Materials and Method: In this research, the effects of climate change on the yield, gross margin and Cropping Pattern of Gorgan County were investigated. For this purpose, at first, by using the regression analysis, the effects of climate variables on temperature and annual precipitation on the yield of selected products during the period of 1367-1396 were investigated. Then, the climate change of the study area was predicted for the upcoming periods (2021-2040), the near future (2051-2070) and the far future (2081-2100) by General Circulation Model HadGEM2. in the end, the region's cultivated area was stimulated by the application of Positive Mathematical Programming (PMP) and the effects of climate change on the cultivated area in the mentioned periods were investigated. Results and discussion: The results showed that climate parameters such as temperature and precipitation have a significant effect on the yield of selected products. Also, by applying predictions of climate change in the cropping pattern model, Potato with 0. 27 and 71. 7 percent increase, the highest increase in yield and cultivated area respectively, and High-quality long-grain rice with 0. 17 percent reduction have the highest decrease in yield and barley with 89. 1 percent reduction have the highest decrease in the cultivated area. and the gross margins of farmers were increased in all three periods. Suggestion: As a result, it could be mentioned that consideration of the effects of climate change and improving the productivity of agricultural products, can decrease the negative effects of this event.

This study was carried out to evaluate the economic and technical effects of climate change on the agricultural sector of Gharehso basin in Golestan province. In the first part, using the IHACRES rainfall-runoff model and rainfall, temperature, and monthly runoff data during the base period (1994-2010), the Ghareso river flow was simulated during the period of 2011-2040. Then, the probabilistic status of water resources allocation and provision of agricultural sector was evaluated by WEAP model. In the second part, in order to reduce the negative effects of climate change on the agricultural sector, using the goal programming economic model, optimal cultivation with the goals of minimum water consumption and maximum future profits was determined. The results of the first part showed that runoff decreases in the upcoming periods by 31. 34% compared to the base period. In addition, the results of the WEAP model indicate an increase in the unmet need of the agricultural sector in the region under study. This result suggests that with the continuation of climate change in the future to reduce the negative effects in agriculture, the region's cultivation pattern should be changed to remove cotton and increase the area of barley and rice. These changes were identified in the results of the second part of the model through the Goal Programming Model. In the optimal cultivation pattern, the gross profit of farmers in the studied area in the period of 2011-2040 increased from 1386 billion Rials to 1991 billion Rials compared to the base year. It is suggested, since the results of the Goal Programming Model have included conflicting objectives (minimizing water consumption and maximizing profit and cultivation area), its results (changed cultivation pattern) should be used as a guide for decision makers.

Modern irrigation systems are considered as a way to both respond to the effects of climate changes and improve the water security. Applying such systems, save the water used in farming activities and consequently made some environmental challenges in terms of increasing energy consumption and greenhouse gas emissions. Although some recent studies analyzed the relationship between water and energy in the agricultural irrigation systems, considering the objectives on productivity, adaptation, and mitigation in a cropping pattern optimization problem is necessary. Climate-Smart agriculture as a strong programming concept, addresses these three objectives and has created the potential for a "triple-win" solution. This study is an effort to fill the study gap on triple-win solution in modern irrigation by developing an integrated economic-hydrological-environmental model called WECSAM at the basin level using a hydrological model called WEAP. For this purpose, a multi-objective optimization model has been developed with the concepts of water footprint, energy footprint, and the greenhouse gas emissions in the context of CSA. We applied the model to the northern region of Bakhtegan basin called Doroodzan irrigation network located in Iran. The result of the WECSAM model indicated that by simultaneously optimizing the conflicting objectives of maximizing profit and minimizing water footprint, energy footprint, and CO2 emissions, as compared to the single-objective model of maximizing economic profit, the water footprint decreases by 8. 2%, Energy footprint decreases by 21. 2%, CO2 emissions decreases by 6. 9% and profit decreases by 7. 4%. The share of each system in irrigating the water-smart, energy-smart, and climate-smart cropping pattern is as follow: 54% for drip system, 26% for semi-permanent sprinkler system, 11% for surface systems, 8% for center-pivot, and <1% for classic permanent sprinkler system.

Global warming is a one of the most important natural hazard in the current world which could affect crop yields through affecting plant physiology, soil water balance and crop water requirement via green and blue water. Under such circumstances, achieving water and food security through an optimal usage of water resources and maintaining crop yield level requires measures for adapting with this major environmental challenge in the future periods. Since wheat and its produces has a the most important share in peoples’ food diet, the climate change effect on wheat cropping calendar and its water requirement in Sistan and Baluchestan province was investigated in this research. Also, the influence of managing sowing date on diminishing the negative effects of this global event was assessed. After calibrating and validating LARS-WG, the climatic variables in six synoptic stations of Zabol, Zahedan, Iranshahr, Saravan, Khash and Chabahar were downscaled under three scenarios of A1B, A2 and B1 of HADCAM3 model up to 2100. Crop water requirement was calculated by determining suitable crop cultivation periods based on cardinal temperature and determining the length of initial, developing, mid-season and late-season stages based of growth degree day coefficient. Climate change decrease the length of different growth stages by 1-20 days due to significant temperature increase which led to 0.03-42.7 percentage decrease in wheat water requirement. Although delaying wheat cultivation will intensify the climate change effects and shorten the growing period by 12-25 days, water requirement will increase by 1.27-778 M3 ha-1.Based on the results, the management ofwheat cultivation calendar can be effective way to achieve sustainable agriculture under future climate condition of the Sistan and Baluchestan province.