Barley (Hordeum vulgare. L) is adapted to drought and salinity as the most critical constrained factors in Iran's crop production. Hence, the grain barley's importance is exhibited via 1.75 million hectares of harvested areas and 3.2 million tons of production in the country with arid and semi-arid climate conditions. However, the current production status meets only about 50% of Iran's barley's grain demands and is globally recognized as one of the largest barley importers in recent years. This study aimed to estimate the potential and yield gap and the potential barley grain production increase under the irrigated and rainfed conditions as the first step in schematizing the promotion of barley production. The impact of determinant climate factors on barley yields was also investigated at dominant barley productions regions over Iran. The present study approach is implemented based on the Global Yield Gap Atlas (GYGA). Accordingly, 12 and 17 designated climatic zones (DCZ), are distinguished as the dominant areas of the irrigated and rainfed barley production in the country, respectively. Afterwards, 48 and 38 reference weather stations (RWSs) within the DCZs were distributed to irrigated and rainfed barley harvested areas, respectively. The SSM-iCrop2 crop model was employed to simulate potential yield in irrigated (Y_p) and rainfed (Y_w) conditions by utilization of required data in each RWS through 15 barley growing seasons (2000–2014). The yield gap (the difference between simulated potential yield (Y_p or Y_w) and actual yield (Y_a)) were calculated based on the bottom-up approach of GYGA in RWSs, DCZs and national-scale, respectively. Based on the results, the estimated potential yield varies between 5283 and 8286 kg/ha (with an average of 7090 kg/ha) in irrigated condition, and in the case of rainfed barley ranged between 1072 and 4002 kg/ha (with an average of 2723 kg/ha). In contrast, the actual yield in the DCZs was reported in the range of 1406 and 3723 kg/ha (with an average of 3009 kg/ha) for irrigated barley and ranged around 390–1510 kg/ha in rainfed conditions (with an average of 1009 kg/ha). According to the results, the DCZs that are confronted with higher temperatures and shorter growth length periods due to less total received daily solar radiation have low yields in irrigated conditions. In rainfed barley harvested areas, a significant correlation between rainfall distribution, high temperature and Yw has existed during the reproductive phase within 17 DCZs. Ultimately, the results indicated that the calculated yield gap varies between 3237 and 4697 kg/ha (50–76%) with an average of 4081 kg/ha (58%), and also between 615 and 3125 kg/ha (53–82%) with an average of 1714 kg/ha (63%) in the DCZs of irrigated and rainfed barley harvested areas, respectively. Consequently, it has been concluded that by achieving attainable yield (80% of potential yield) via improving production management, irrigated barley yield production can be increased to 5672 kg/ha and 4.17 million tons, respectively, provided that water resources are available. It can also be exploitable to increase rainfed barley's current yield and production from 1009 to 2178 kg/ha and 1.05–2.26 million tons, respectively. Finally, it makes sense to be inspired by increasing total national barley production from 3.26 to 6.43 million tons per year and bring the country closer to obtain full self-sufficiency in supplying the required barley grain.

大麦（大麦。L) 适应干旱和盐度作为伊朗作物生产中最关键的制约因素。因此，在干旱和半干旱气候条件下，大麦的重要性体现在 175 万公顷的收获面积和 320 万吨的产量上。然而，目前的生产状况仅能满足伊朗大麦粮食需求的 50% 左右，被全球公认为近年来最大的大麦进口国之一。本研究旨在估算灌溉和雨育条件下的潜在和产量差距以及潜在的大麦籽粒产量增加，作为计划化促进大麦生产的第一步。在伊朗的主要大麦产区也调查了决定性气候因素对大麦产量的影响。本研究方法是基于全球产量差距图谱 (GYGA) 实施的。因此，12 个和 17 个指定气候区（DCZ）分别被区分为该国灌溉和雨育大麦生产的主要区域。之后，DCZ 内的 48 个和 38 个参考气象站 (RWS) 分别分布到灌溉和雨育大麦收获区。SSM-iCrop2 作物模型用于模拟灌溉（Y DCZ 内的 48 个和 38 个参考气象站 (RWS) 分别分布到灌溉和雨育大麦收获区。SSM-iCrop2 作物模型用于模拟灌溉（Y DCZ 内的 48 个和 38 个参考气象站 (RWS) 分别分布到灌溉和雨育大麦收获区。SSM-iCrop2 作物模型用于模拟灌溉（Y_p ) 和雨养 (Y _w ) 条件，通过 15 个大麦生长季节（2000-2014 年）在每个 RWS 中使用所需数据。产量差距（模拟潜在产量（Y _p或 Y _w）与实际产量（Y _a)) 分别基于 GYGA 在 RWS、DCZ 和国家规模的自下而上方法计算。根据结果​​，在灌溉条件下，估计的潜在产量在 5283 和 8286 公斤/公顷之间（平均为 7090 公斤/公顷），在雨育大麦的情况下，在 1072 和 4002 公斤/公顷之间（平均2723 公斤/公顷）。相比之下，据报道，灌溉大麦在 DCZ 的实际单产范围为 1406 至 3723 公斤/公顷（平均为 3009 公斤/公顷），而雨育条件下的实际单产范围为 390-1510 公斤/公顷（平均1009 公斤/公顷）。结果表明，由于每日接收的太阳辐射总量较少而面临较高温度和较短生长期的DCZ在灌溉条件下产量较低。在雨育大麦收割区，在 17 个 DCZ 的繁殖阶段，降雨分布、高温和 Yw 之间存在显着相关性。最终，结果表明，计算出的产量差距在 3237 和 4697 公斤/公顷（50-76%）之间变化，平均为 4081 公斤/公顷（58%），也在 615 和 3125 公斤/公顷之间（53-82 %），在灌溉区和雨育大麦收获区的 DCZ 中，平均产量分别为 1714 公斤/公顷（63%）。因此，得出的结论是，通过改进生产管理实现可达到的产量（潜在产量的 80%），在水资源可用的情况下，灌溉大麦产量可分别提高到 5672 公斤/公顷和 417 万吨。它还可用于将雨育大麦目前的单产和产量从 1009 公斤/公顷提高到 2178 公斤/公顷和 1.05–2。分别为2600万吨。最后，将全国大麦总产量从每年 3.26 吨增加到 643 万吨，并使该国更接近于实现所需大麦粮食的完全自给自足，这是有意义的。