In order to evaluate the effect of N and P bio fertilizers on yield and yield components was laid out the environment in which crops will be grown in the future will change. Climate change can be expected to impact on agriculture, potentially threatening established aspects of farming systems but also providing opportunities for improvements. This study investigated the impacts of elevatedatmosphericCO2 concentrations and associated changes in climate on winter wheat yields in Gorgan, Iran. The analysis was based on climate change predictions of two global circulation models (GCMs) for two greenhouse gas emission scenarios (A1B and A2) during three time periods in the 21st century (2020, 2055 and 2090). Climate change predictions by two GCMs used in this study suggested a consistent pattern of increase in mean season air temperature and this increase is more pronounced under the aggressive emission scenario. Two models suggest various levels of reduction in radiation, under all scenarios and all time periods and in all cases the amounts of reduction for summer were greater than other seasons. Season precipitation experienced various levels of reduction, although with less variability than air temperature, depending on the model used and the scenario considered. A simple simulation model for wheat (SSM) successfully simulated contemporary wheat yields. Irrigated and rain fed wheat yield change by -2.35 to 9.21% and 17.2 to 82.56% under future climate conditions, respectively. It can be concluded that increase in the amount of carbon dioxide in future climate conditions in Gorgan can compensate the negative effects of rise in temperature.

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