Wheat grain yield and water use efficiency improved under climate change condition in semi-arid regions as predicted by APSIM crop model

Abstract

The present study investigated the effect of climate change on crop productivity and water use efficiency at the regional scale. A general circulation model (HadCM3) was applied for two emission scenarios (A1B and A2) for three periods (2011-30, 2046-65 and 2080-2099) at nine locations in Fars province in central Iran. The APSIM crop model was used to simulate growth and development of wheat as well as water use efficiency under future climate scenarios. The results indicated that average temperature over the growing season increased from 12.15°C at baseline to 13.22°C in all future scenarios. The increase in CO2 concentration to 674 ppm in 2099 under A1B neutralized the negative effects of high temperature during the growing season and improved crop yield. Wheat grain yield increased from +10 to +41% over baseline for all future emission scenarios and periods at all study locations. The results indicate that, by the end of the century under the A2 emission scenario 10% to15% of Fars province will have a grain yield of more than 10 t ha-1 and about 65% will have a grain yield of 8 to 10 t ha-1. Averaged across locations, scenarios and periods, water use efficiency increased by 3.56 kg ha−1 mm−1 in the future scenarios over baseline. The improved water use efficiency under future climate change was largely the result of a significant increase in yield (from 6989.5 kg ha−1 at baseline to 8416.5 kg ha−1 in all future scenarios) and decreased evapotranspiration (from 506.8 mm at baseline to 478 mm in all future scenarios). A decrease in evapotranspiration as well as an increase in water use efficiency under future climate change could be beneficial for agricultural production systems, particularly under semi-arid conditions.