| Abstract: |
Cotton is the main cultivated cash crop in Northwest China. This study is motivated by the challengeof economically growing cotton in the face of climate change, which could lead to changes in cottonvariety, phenology, water demand, heat requirement and yield. The APSIM-OzCot crop growth modelis used to simulate cotton cultivation at two sites with different climatic conditions (Shihezi and Alaer,Xinjiang Province). The model is fully calibrated and validated using observations. Simulations forcedwith future climate data downscaled from the HadCM3 Global Climate Model show that the responseof cotton phenology, yield and water use to climate change is different for different cultivation, sites,greenhouse gas emission scenarios and time horizons. Under the SRES A1B and B1 emissions scenarios,cotton yield and water use are greater in the future than in the 1961–1990 period while the growingseason is shorter. Under the SRES A2 emissions scenario, however, yields at cold sites drop after 2070due mainly to the shortening of cotton growth periods. Thus, in the cold regions, varieties with shortgrowth periods are replaced by those with long growth periods. The results show that, compared withcurrent local varieties, cotton yields increase by 356 kg/ha with the medium maturity variety “K7” and473 kg/ha with the late maturity variety “ZM49” under the A2 scenario by 2070. Total evapotranspirationcorrespondingly increases by 69 mm (“K7”) and 92 mm (“ZM49”). However, water use efficiency increasesby 0.32 kg/m3to 0.34 kg/m3(6.3%) and 0.35 kg/m3(9.4%) for “K7” and “ZM49”, respectively. A reasonableadaptive strategy to maintain cotton yields in the future may be to decrease the area over which cottonis planted and raise water use efficiency. |
