Water use efficiency and crop water balance of rainfed wheat in a semi-arid environment: sensitivity of future changes to projected climate changes and soil type

摘要: Wheat production is expected to be affected by climate change through changing components of the crop water balance such as rainfall, evapotranspiration (ET), runoff and drainage. We used Agricultural Production Systems Simulator (APSIM)-wheat model simulate potential impact on field balance, ET use efficiency (WUE) under SRES A2 emissions scenario. ran APSIM with daily data statistically downscaled from 18 Global Circulation Models (GCMs). Twelve soil types varying plant available holding capacity (PAWC) at six sites across semi-arid southeastern Australia were considered. Biases in GCM-simulated bias-corrected against observations for 1961–1999 baseline period. However, biases output relative simulations forced remained. A secondary bias correction was therefore performed outputs. Bias-corrected outputs a future period (2021–2040) compared generated using obtain changes. The results show that effective rainfall decreased over all due growing season rainfall. reduced evaporation transpiration. There no significant changes any site. variation deep drainage between much greater than runoff, ranging less few millimetres drier 100 mm wetter. general, averaged different not significantly (1961–1999) 2021–2040 (P > 0.05). For wetter sites, variations GCMs larger those sites. At dry PAWC increased. Overall, based transpiration (WUE_T) (WUE_ET) increased 1.1 1.6 0.7 1.3 kg ha−1 mm−1, respectively, historical climate. Significant relationships wheat yield only seen three high one low PAWC. Conversely, opposite response two highlighting importance determining interactive crops primary balance.