determination of weather conditions associated with the production of rainfed barley crop )case study: east azerbaijan(

temperature and precipitation are two climatic variables haveing the most significant impact on the variability of crops yield. in this study, the relationship between rainfed barley yield, temperature and rainfall were assessed with both simple correlation and iterative chi-square analysis for eastern azerbaijan in four districts (tabriz, maragheh, sarab and miyaneh). the iterative chi-square analysis identified relationships of low and high yield years to the maximum and minimum of temperatures and rainfall. the same patterns in all regions found in the relationship between rainfed barley yield and climatic indicators. in all regions,the main climatic factors limiting rainfed barley production were low,high and very high temperatures occurring during february (cardinal value rang, t min ≤ -10 °c to t min ≤ -20°c), before the onset of winter (cardinal value rang,t max≥15 °c to tmax≥20°c ) and at anthesis stage(early may to early june) (cardinal value ranging, tmax ≥ 25 °c to t max ≥ 35°c ) respectively. cold nights (cardinal value rang, t min ≤ 10 °c to t min ≤ 20°c) and enough rainfall (cardinal value ranging, pp ≥ 5.8 mm to pp ≥ 10.6 mm ) led to increasing yield in ripening stage (early june to early august) and in the early planting respectively. in all regions, the anthesis stage was the critical time in which high temperatures and low precipitation led to yield loss. determine the impact of temperature and rainfall on crops yield provides advantage information for adopting appropriate management practices in order to decrease adverse effects.