Improvement of water productivity is very essential for achieving water and food security. One of the basic strategies in this field is determination of crop yield gap and water productivity gap, which is the difference between the present actual situation and the potential situation. This research was carried out for wheat in Qazvin province according to GYGA protocols, which is an international methodology. At first, the map of climatic zones of the province was prepared based on Emberger method by using GIS. Then potential yield gap of wheat was estimated according to calibration and simulation of version 5 of Aqua crop model. Results showed that yield gap in various climate zones of the province was between 4502-6271 kg/ha, evapotranspiration water productivity gap was between 0. 56-0. 66 kg/m3 and water (irrigation and effective rain) productivity gap was between 0. 57-0. 71 kg/m3. Results showed that actual wheat yield in Qazvin province is 37 percent of the potential yield. Also, relative evapotranspiration water productivity index was 0. 47 and relative water productivity index was 0. 31. These indices show the ratio of the actual to potential productivities. Based on this research results, the extent of gap between optimum and current condition of yield and water productivity is very wide. Yield gap is 63% of potential yield and water productivity gap is 69% of potential water productivity. This issue represents the considerable weakness existing in management of agricultural production and irrigation and reflects the potential opportunities for strengthening these operation, improving water productivity, decreasing the pressure on water resources, and increasing food security.

Introduction Barley (Hordeum vulgare L. ) is considered as the second most important grain crop after wheat, due to 1. 75 million hectares harvested areas and 3. 2 million tons’ production in Iran. The irrigated fields are contributed up to 45% of total barley harvested areas (equivalent to 1. 7 million ha) and 70% of total barley production (equivalent to 2. 2 million tons). Based on the statistics reported in recent years, about 2. 5 million tons of barley imported from other countries. According to the impossibility of extending the barley cultivated areas and even the necessity of reducing fields in some parts of the country, increasing productivity per unit area of cultivated lands is recognized as the only practical way to boost the production of barley in Iran. In this regard, this study was conducted to estimate barley yield gap (Yg) and the potential of increasing barley production in irrigated condition as the first step to promote the yield and production of barley over the country. Materials and Methods Firstly, the main production zones of barley are determined; the zones which were contributed in more than 85% of barley production. The Designated climatic zones (DCZs) were identified using GYGA climatic zones (Global Yield Gap Atlas) and the distribution of barley harvested area raster layers. Subsequently, the Reference weather Stations (RWSs) within the DCZs were selected based on the values of the harvested area, and the types of soil in each of RWSs were determined by using of HC-27 soil map. SSM-iCrop2 as a crop simulation model has been employed to estimate the potential yield (Yp) in the RWSs of cultivated areas, which has previously been parameterized and evaluated, and the results have indicated the robustness of the model for simulating barley yield over the country. For estimating Yg, the data of actual yield (Ya) and the agronomic management data for estimating Yp during 15 growing seasons (2000-2014), were collected at RWSs scale. Using A bottom-up approach, the yield, and production gap values were calculated at RWSs and subsequently aggregated to DCZs and finally, extended from DCZ to country-level according to the spatial distribution of crop area and climate zones. Results and Discussion Based on GYGA protocol, 48 RWSs within 12 DCZs of irrigated barley harvested areas were demonstrated. Aggregation from the RWSs results to DCZs illustrated that the average of potential yield in DCZs of irrigated barley was estimated 7090 kg. ha-1 and the range varied from 5283 to 8286 kg. ha-1. Nevertheless, the Ya range in these climate zones was calculated between 1406 and 3723 with an average of 3009 kg. ha-1. According to the results, the DCZs which confronted to higher temperatures during the growing season have lower yields and also a significant reverse correlation between the potential yield and the growth length period (R2 = 0. 88 and p ≤ 0. 01) were shown. The correlation between total received daily solar radiation during the growing and Yp in the DCZs was significant, positively season (R2 = 0. 98 and p ≤ 0. 01). At present, the range of difference between actual and potential yield varies between 3237 to 4697 kg. ha-1 with an average of 4081 kg. ha-1 (equivalent to 58% yield gap). In other words, just around 24 to 50 percent (on an average of 42 percent) of estimated Yp in irrigated barley fields can be attainable. According to the irrigated barley harvested areas, the actual and potential production gap are calculated about 2. 21 and 2. 99 million tons in the country, respectively, and under the best management condition can lead the production to be about 4. 17 million tons. Conclusion According to the results, it was demonstrated about 58% relative yield gap between the averages of actual yield (3008 kg. ha-1) and potential yield (7090 kg. ha-1), which can be reduced by improving the production management in irrigated barley cultivated areas. For this reason, the current production of barley in irrigated lands can be increased from 2. 12 to 4. 17 million tons. This increase in production (1. 96 million tons) could provide a significant part of the country's need to the barley and bring the country closer to achieve full self-sufficiency.

Background and objectives: Wheat has an important role in feeding the people of world and Iran as well. It provides around 40 percent of edible energy and protein for people in Iran. Closing yield gap can increase wheat production, significantly. The first step of closing yield gap is to quantify the yield gap at a given region or country. The amount of wheat yield gap hasn’ t been measured for whole Iran by a global standard protocol so far. The aim of this study is to estimate irrigated wheat yield gap for Iran based on the global yield gap analysis (GYGA) protocol. Materials and methods: GYGA protocol suggested a method to calculate yield gap on a large scale like a country. Based on this protocol, at first the area covered by each weather stations were specified. Second, the main weather stations where cover irrigated wheat lands were selected named reference weather stations (RWS). Third, irrigated wheat potential yield was estimated by SSM-iCrop2-wheat simulation crop model within the RWSs. The actual irrigated wheat yield was calculated for each RWS based on GYGA protocol as well. Forth, amount of the actual and potential yield was calculated for whole country by using the values calculated for the RWS according to GYGA protocol. Finally, the yield gap was calculated by difference between potential and actual yield for the country. Results: The results of this study showed that average irrigated wheat in Iran was 3. 4 ton/ha, average potential yield was 8. 8 ton/ha and average yield gap was 5. 4 ton/ha (62%). At the moment, irrigated wheat producers just use 38 present of the existing wheat cultivars and environment potential. There was no significant relationship between climate in the irrigated wheat production RWS and irrigated wheat yield gap (based on percent) in Iran and the yield gap was around 62 percent in all the RWSs. If farmers could reach 80% of potential yield of their locations, by improving agronomy practices, average irrigated wheat would reach 7 tons/ha and there is around 2. 2 million ha irrigated wheat area in Iran. Thus, average wheat production in irrigated condition would increase from 7. 5 million tons to 19. 8 million tons. Conclusion: Owing to existing wheat cultivars and climates in the main irrigated wheat production RWS in Iran, there is a big yield gap of wheat in Iran. The low actual irrigated wheat yield in Iran (3. 4 tone/ha) can be attributed to the poor management condition because the existing cultivars and climates have no limitation to reach the yield around 8. 8 tone/ha. There are many factors to reduce the yield such as poor seedbed preparation, late planting date, weeds, pests and diseases, nutrition’ s deficits, fertilizer amount and timing, irrigation amount and timing etc. If we want to close the yield gap, we have to identify the reasons of yield gap in a given region.

Introduction Potato (Solanum tuberosum L. ) accounts for the largest share in production of food products after wheat, rice and corn, which plays an important role in the nutrition and food basket of the world. Currently, the issue of food security and supplying is very important in different parts of the world and thus prediction of its demand that is increasing. Also, growing population will intensify this issue too. A key strategy to overcome the nutritional challenge of the growing population of the world is eliminating the gap between the current achievement in farms and the yield which can be achieved by using the best cultivars compatible with the environment and the best water, soil and plant management methods. Martials and Methods In this study, potential yield of potato was estimated using the SSM-iCrop2. then the production and yield gap of potato were investigated with two methods of Global Yield Gap Atlas (GYGA) and Arc GIS software by interpolation method for Golestan province. For this aim, the information of potato cultivation management in the province level and the daily data of 23 synoptic weather station as well as their soil data were used. Meanwhile, potential yield gap analysis protocol (GYGA protocol) was used to identify the main weather stations named reference weather stations (RWSs) and climates where potato is planted in Golestan province. Potential yield of potato was estimated within the area covered by each RWS, and then scaled up to the province level. In order to implement the interpolation method in ArcGIS software, initially, potential yield of 23 stations in the Golestan province was estimated. Afterwards, the potential and actual yield in the whole province was estimated using Kriging and IDW methods, respectively. Results and Discussions According to the Agricultural Jihad Report, the actual yield of Golestan province (a ten-year average) was reported as 22 t. ha-1, while the actual yield calculated based on the interpolation method was estimated equal to 22 t. ha-1. However, the actual yield calculated using the global yield gap atlas (GYGA) method was estimated as 20 t. ha-1. Heigh yield of potato in the province was reported by farmers up to 55 tons, which was considered as potential in the province to be compared with GYGA and interpolation methods, so that in the GYGA method, 52 t. ha-1 and in the interpolation method, finding was 42 t. ha-1. yield gap and relative yield in the GYGA method (33 t. ha-1 and 38 percent), and interpolation (20 t. ha-1 and 52 percent) were obtained. Also, in GYGA method, the values ​ ​ were estimated using only two stations, but in the interpolation method the province's yield was estimated using 23 stations and daily meteorological data. The GYGA protocol is a bottom-up approach used by Hochman et al. (2016) to assess the variation of national yield from climatic zoning to analyze similar agro-cluster groups. So far, several studies have been done using this protocol. Gobbett et al. (2017) showed that wheat lands in Australia are located in six key climatic regions. They selected 22 reference stations in this area and calculated the limited water potential yield using the APSIM model (for the years of 1996 to 2010). Conclusion The results showed that both Global yield gap Atlas (GYGA) and interpolation method had accurate estimation of actual and potential production and yield, but those values obtained using statistics and 23 weather stations in the interpolation method, and using just 2 weather station (Hashemabad and Gorgan stations) in the Global Atlas method. As previously mentioned, the GYGA method is designed to estimate the yield gap at the national level, which can calculate the potential yield, production, and yield gap in a wide range even with the least amount of information. One of the advantages of GYGA protocol is that the results obtained at any point in the world are comparable to other areas and cultivations of that particular product. Based on the comparison made in this study, it was concluded that the Global yield gap Atlas method should be used to estimate the yield of the country.

Introduction Occurrence of drought and reduction of rainfall in the future will limit the cultivation of irrigated crops. Thus, it is probable that a part of the present irrigated lands and orchards of Iran may be unavailable for the cultivation of irrigated crops, but it is possible to cultivate rainfed crops in these lands. However, the available potential for cultivation of rainfed crops with respect to the soil type, climate and other factors is not known. Limited water resources, on the one hand, and the growing population along with increasing the need to produce food, on the other, make it necessary to have a comprehensive, practical and accurate program. Therefore, research on this issue is essential. In this study, production potential of rainfed wheat (Triticum aestivum), barley  (Hordeum vulgare L.), chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik) and canola (Brassica napus)  in irrigated lands (fields and orchards) was modeled.Materials and Methods  Weather stations (position and distribution), long-term weather data (15 to 30 years), HC27 soil map, crop management data plant parameters were used to determine the yield in this study using SSM-iCrop2 model. In each zone, the yield was determined and compared with the actual data. In other words, the model output were compared with the actual current rainfed yields of each province and then it was determined that whether the model precision was sufficient for this study. Other calculations (determining the average yield of provinces) and generation of maps were done using ArcGIS V.10.2. The yield obtained by farmers in these lands was considered as 50 and 70 percent of yield potential. Also, the yields were categorized into four classes of excellent, good, medium and non-suitable. This classification is based on economic- agronomic profit of crop harvest.Results and Discussion The results of this study showed that the conditions of rainfed production in each province of the country is suitable/appropriate for some crops and unsuitable/inappropriate for some other. In case the yield of farmers reached 70 percent of yield potential by optimum management, all provinces will be classified into the upper average group (3, 18 and 10 provinces in excellent, good and medium groups) for wheat. For barley 30 (3, 10 and 17 provinces in excellent, good and medium groups), for chickpea 30 (3, 6 and 21 provinces in excellent, good and medium groups), for lentil 31 (13 and 18 and 10 provinces in good and medium groups) and for canola 30 (4, 5 and 21 provinces in excellent, good and medium groups) provinces will be placed in the upper average group. Based on 70 percent of yield potential of canola, barley and chickpea, only on province is placed in non-suitable group. On the other hand, in case the yield of farmers reaches 50 percent of yield potential due to improper management, for wheat 30 (2, 2 and 26 provinces in excellent, good and medium groups), for barley 28 (4 and 24 provinces in good and medium groups), for chickpea 18 (4 and 14 provinces in good and medium groups), for lentil 28 (3 and 10 provinces in good and medium groups) and for canola 25 (5 and 20 provinces in good and medium groups) will be classified into the upper average group. Based on 50 percent of yield potential of rainfed wheat, barley, canola, chickpea and lentil, 1, 3, 6, 13 and 3 provinces were placed in non-suitable group, respectively.Conclusion According to the results of this study, a major part of the provinces will be placed in medium and non-suitable groups in case of improper management, and agricultural productions will not satisfy the needs of the country. Therefore, it is necessary to pay a special attention to agronomic management of rainfed crops, as the agricultural production of the country will not be acceptable unless 70 percent of yield potential is achieved.

Background and objectives: Barley (Hordeum vulgare. L) is well adapted to drought and saline conditions as the most important limiting factors for crop production in Iran. This consistency, as well as widespread application in animal feeding, are the reasons for cultivating approximately 1. 77 million hectares of barley, in which, 1. 04 million hectares was attributed to rainfed barley. The previous studies demonstrated that there was a significant difference between the actual and potential yield of crops due to farm management condition. According to the calculated yield loss, the optimized crop field management is necessary to increase agricultural production. This study was aimed to estimate the yield and production gap of barley under rainfed condition as the first step in the terms of the schematization of stable increase in Iran. Materials and Methods: This study is conducted based on the Global Yield Gap Atlas (GYGA) Protocol. As the first step in the implementation of present study, the main rainfed barley harvested areas were determined using GYGA climate zones and the distribution of rainfed barley harvested area maps and the country's meteorological station points layer. After defining the designated climate zones (DCZs) and the reference weather stations (RWSs), the collected data (2000-2014) of agronomic management, meteorological and soil characteristics in each region were employed to estimate the potential yield at the RWSs of rainfed barley as one of components of the yield gap calculation. Estimating barley potential yield under water-limited condition (Yw) was carried out by SSM-iCrop2 during 15 growing seasons. Moreover, the actual yield (Ya) data of rainfed barley was collected at the RWS level as another constituent for yield gap calculation. In the end, the estimated rainfed barley yield gap (Yg) in the RWSs was aggregated to DCZs and finally country-level. Results: In the current study, 38 RWSs within 17 DCZs of rainfed barley harvested areas were identified. The results showed that the average Yw was estimated 2723 kg. ha-1 and the range varied from 1072 to 4002 kg. ha-1. Ya range in the zones were calculated between 390 and 1510 with average of 1009 kg. ha-1. The results illustrated that there was a significant correlation between mean rainfall and maximum temperature during anthesis to harvest maturity period and Yw within 17 DCZs. Hence, with simultaneous increase in rainfall and decrease in average maximum temperature during this phenological period, concomitantly, the Yw value has been amplified. Yg values was estimated between 615 to 3125 kg. ha-1 (equivalent to 53 to 82% of yield gap (%)) with an average of 1714 kg ha-1. Improving the current management conditions to advance toward the attainable yield (Ya) (equivalent to 80% of Yw) in farmers' lands, can increase the average yield of rainfed barley from 1009 to 2178 kg ha-1. Based on the results, the country's production will grow from 1. 05 million tons to 2. 26 million tons in rainfed conditions through increasing yield to the level of attainable yield (80% of potential yield). The rate of barley import from other countries will decrease due to improvement in the production. Conclusion: Our results showed 85 percent of rainfed barley production had been attributed to 17 designated climate zones. Due to the presence of 63% yield gap in rainfed barley fields, by considering 80% of this value as exploitable yield gap, the production can be increased to about 1. 22 million tons which is appreciable for the economical and food security issues in Iran. It is not feasible to achieve the potential yield at the farmer level owing to existing constraints, but approaching the attainable yield by improving field management conditions can be accessible in the current situation.

Common bean (Phaseolus vulgaris L.) due to its high nutritional value has an effective role in ensuring food security of the community. In Iran, protein supply is mainly dependent on plant products, and any action to improve the yield and production of protein-rich crops, which are headed by legumes, is of particular importance. Increasing yields by optimizing production management and eliminating yield gaps is the most appropriate way to increase crop production and improve food security. Therefore, accurate estimation of potential yield and yield gap and crop production is essential for sustainable food supply. The present study aims to estimate the yield gap and production and water productivity of bean in its main climate zones in Iran based on the Global Yield Gaps Atlas (GYGA) project at the Gorgan University of Agricultural Sciences and Natural Resources was done in 2016. In order to estimate the beans yield gap and water productivity in Iran according to GYGA protocol, first the data related to farmers' yield (Ya) and bean harvested areas and production in the country in a period of 15 years from 2001 to 2015 from the Ministry of Agriculture of Iran was prepared. Then the distribution map of beans in the country was prepared. By combining the distribution map of the bean harvested areas and the climatic zoning map of the country, the main climatic zones (DCZs) of bean production were identified. Then, reference weather stations (RWSs) were selected according to the level of each climatic zone. In order to estimate the potential yield (Yp) and water productivity (Wp) based on weather data and major soil type and agronomic management meteorological in each of the selected areas, the SSM-iCrop2 simulation model was used, which was locally calibrated and evaluated. Finally, the bean yield gap (Yg) was calculated from the difference between the potential and actual yield of each RWSs was upscaled to DCZs and country-level. The results of comparing the average of beans actual yield reported by the Ministry of Agriculture of Iran with the actual yield calculated according to the GYGA protocol for the country with RMSE, CV and r values of 84 kg ha-1, 4% and 0.96 respectively, which indicated using This protocol can estimate the average yield of bean in the country with high accuracy. The average beans actual yield in Iran during the years 2001 to 2015 varied between 1.6 and 2.3 ton ha-1. Also, the average actual yield in the main climatic zones of production was 1.9 and between 1.1 (climatic zone 4202 in Germi) to 2.3 ton ha-1 (in climatic zone 3003 in Avaj). Bean potential yield was estimated from 3.4 (in climate zone 4202 in Germi) to 5.4 ton ha-1 (in climate zone 4103 in Hamedan and Bijar) with an average of 4.5 ton ha-1. Based on results, in the main climatic zones of bean production in Iran, there is a yield gap of 1.8 to 3.5 (average 2.6) ton ha-1, equivalent to 46 to 67% (average 57%). The average water productivity potential for bean in Iran was estimated to be 0.76 kg m-3. According to the results, if the factors causing the yield gap are eliminated by optimizing the management of bean production and cultivation and bringing the yield of bean fields to attainable yield (80% of potential yield), is increasing grain yield from the current value of 1.9 to 3.6 ton ha-1 with the same harvested areas, bean production in Iran will increase from the current 222,705 to 415,822 ton, which is equivalent to 46% increase in production and is considered an important step in improving food security.

Yield gap analysis is a quantitative estimate of possible increase of the capacity to provide food for a specified area. It is an important component for designing strategies to supply food on a scale of regional, national, and global level. In this regard a study has been conducted to determine the extent and function of chickpea and lentil crop vacancy distribution at Gorgan University of Agricultural Sciences and Natural Resources during 2016-2018. Using SSM-iCrop2 model, the study simulates potential yield in chickpea and lentil producing regions in Iran. For this purpose, it employs the protocol of Atlas Gap Project, called GYGA protocol, to identify climatic zones and identify important meteorological stations, located in chickpea and lentil production areas in the country. After identifying the important stations, the performance potential for the station range is simulated and then the regional results are generalized to the whole country, based on the GYGA protocol. For dryland chickpeas in the country, the values of actual and potential yield as well as yield gap have been 0. 43, 1. 04, and 0. 61 tons per hectare, respectively. In case of rainfed lentils in the country, the values of actual yield and potential along with yield gap have been 0. 43, 1. 10, and 0. 67 tons per hectare, respectively. The present study can be used for better management in low-yield and high-yield areas of the country for these two products.

The present study tries to estimate the yield gap of irrigated canola in Iran as the first step for planning sustainable improvement of production. It has been performed in the modeling laboratory of Gorgan University of Agricultural Sciences and Natural Resources in 2017-2019. The protocol provided by the GYGA project is used for detection of climatic zones as well as major weather stations in canola production regions to estimate the yield gap. The actual yield of the irrigated canola in its major production regions is between 1184 to 2358 kg ha-1. The range of potential yield is estimated between and 3823 and 6520 kg ha-1. The highest potential yields belongs to Hamedan and Lorestan provinces and the lowest value to Khuzestan Plain. The range of the yield gap in its major production regions in the country is 2480 to 4365 kg ha-1, i. e. 53% to 77% of gap and with an average, 3276 kg ha-1 equal to 65% of the gap. With respect to the exploitable yield as the target yield, the exploitable yield is between 1544 and 3208 kg ha-1, with an average of 2261 kg ha-1. The magnitude of this gap indicates that the potentials of canola production in Iran are not exploited properly. Analyzing the reasons and methods of amendment the present yield gap and adoption of efficient management methods to achieve higher yields is crucial with regard to food security and economic.

Global climate change is among the most important agricultural and food security challenges. This study tries to investigate the effect of climate change on potential yield and water productivity of forage maize (Zea mays L. ) in Iran. Two scenarios of RCP4. 5 and RCP8. 5 are used to predict the future climate (2050s) and climate data of 2001-2015 have been used as the base period. Potential yield is estimated using SSM-iCrop2 model according to the GYGA protocol and the climate changes for both scenarios are applied in the model. The results show that the climate change will not have a considerable effect on forage maize yield compared to the current conditions (85. 6 ton ha-1) and will only lead to an increase of 0. 9% and 1. 6% in on both scenarios, respectively. This may be attributed to maize being a C4 plant and thus noneffectiveness of CO2 increase on its growth. Also, the temperature will remain in optimum range for maize in most of the main regions for forage maize cultivation areas in Iran. Water productivity in both scenarios will increase by 0. 4% and 1. 6%, compared to current conditions (10. 4 kg m-3), respectively, which may be due to increased CO2 concentration and more closure of stomata. Also, improved water productivity in forage maize may be attributed to increase yield potential due to the fact that no considerable changes are observed in terms of the required water, evapotranspiration and irrigation times.