Projecting staple crop production including wheat under future climate plays a fundamental role in planning the required mitigation strategies for climate change effects especially in developing countries. The main aim of this study was to investigate the direction and magnitude of climate change impacts on grain yield of rainfed wheat production and precipitation within growing season. This study was performed for various regions in Khorasan province which located in northeast of Iran. Climate projections of two General Circulation Models for four locations under three climate change scenarios were employed in this study for different future time periods. The model LARS-WG5 was used for downscaling to generate daily climate parameters from GCMs output. The Decision Support System for Agrotechnology Transfer (DSSAT) Version 4.5 was employed to evaluate rainfed wheat performance under future climate. Grain yield of rainfed wheat and precipitation during growth period considerably decreased under different scenarios in various time periods in contrast to baseline. Highest grain yield and precipitation during growth period was obtained under B1 scenario but A1B and A2 scenarios resulted in sharp decrease (by -57%) of grain yield. Climate change did not indicate marked effects on evapotranspiration during the rainfed wheat growth. A significant correlation was detected between grain yield, precipitation and evapotranspiration under climate change for both general circulation models and under all study scenarios. It was concluded, that rainfed wheat production may overally declined during the next 80 years especially under A2 scenario. Therefore, planning the comprehensive adaptation and mitigation program is necessary for avoiding climate change negative impact on rainfed wheat production.

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