Modelling global change impacts on wheat cropping in south-east Queensland, Australia

The wheat module I-WHEAT, from the APSIM cropping system model was used to investigate the impacts of changes in atmospheric CO₂ concentrations on wheat crops by modifying radiation use efficiency, transpiration efficiency, specific leaf area and critical nitrogen concentrations. The effects of several combinations of atmospheric CO₂, climate change and crop adaptation strategies on wheat production in the Burnett region were studied. Mean wheat yields were increased under doubled CO₂, with the response relative to ambient CO₂ greatest in dry years. Higher temperature under the climate change scenarios moderated the yield gains achieved with increasing CO₂ and in some instances reversed them under the reduced rainfall scenario. The status of the region as a producer of prime hard wheat may be at risk due to reduced grain protein levels under doubled CO₂ and the increased likelihood of 'heat shock' in the climate scenarios used.