CR prepress abstract  -  doi: 10.3354/cr01458

Spatiotemporal changes of wheat phenology, yield and water use efficiency under the CMIP5 multimodel ensemble projections in eastern Australia

Bin Wang*, De Li Liu, Senthold Asseng, Ian Macadam, Xihua Yang, Qiang Yu

*Email: bin.a.wang@dpi.nsw.gov.au

ABSTRACT: The New South Wales (NSW) wheat belt is one of the most important regions for winter crops in Australia, with its agricultural system being significantly affected by water stress and ongoing climate change. Statistical downscaled scenarios from selected 13 GCMs with RCP4.5 and RCP8.5 scenarios were combined with crop simulation model to simulate wheat productivity and water use. We projected that multi-model median yields could increase by 0.2% for RCP4.5 and 9.0% for RCP8.5 by 2061-2100. Although the RCP4.5 showed a small decrease in median yield in the dry southwestern parts of the wheat belt, the higher CO2 concentration in RCP8.5 compensated some of the negative effects resulting in 12.6% yield increase. Our results show that drier area would benefit more from elevated CO2 than wetter area. Without the increase in CO2 concentration, wheat yields decrease rapidly under RCP4.5 by 2061-2100 and much more so under RCP8.5 compared to the present. A decline in growing season length and a decrease in rainfall resulted in a reduction of crop water consumption. As a consequence, simulated evapotranspiration decreased by 10.2% for RCP4.5 and 16.9% for RCP8.5 across the NSW wheat belt. Increasing yields combined with decreasing ET resulted in a simulated increase in water use efficiency by 9.9% for RCP4.5 and 29.7% for RCP8.5. Wheat production in water-limited, low yielding environments appears to be less negative impacted or in some cases even positively affected under future climate and CO2 changes, compared to other growing environments in the world.