Responses of crop growth and water productivity to climate change and agricultural water-saving in arid region

Climate change and associated elevated atmospheric CO₂ concentration and rising temperature have become a great challenge to agricultural production especially in arid and semiarid regions, and a great concern to scientists worldwide. Thus, it is very important to assess the response of crop growth and water productivity to climate change projections, which in turn can help devise adaptive strategies to mitigate their impact. An agro-hydrological model with well consideration of CO₂ effects on both the stomatal conductance and leaf area was established. The model was well calibrated and validated using the data collected from the middle oasis of Heihe River basin, northwest China, which was selected as a typical arid region. Simulations of soil water contents and crop growth matched well with observations. Then various scenarios were designed with considering three climate change alternatives (RCP 2.6, RCP 4.5 and RCP 8.5) and three agricultural water-saving alternatives in the context of irrigation water availability being constant. Responses of crop growth and water productivity were predicted for thirty years from 2018 to 2047. As compared to current situation, there would be a reduction of 3.4-8.6% in crop yield during the period of 2018-2027 and an increase of 1.5-18.7% in crop yield during the period of 2028-2047 for seed corn, and an increase of 7.4-26.7% in crop yield during the period of 2018-2047 for spring wheat, respectively. Moreover, results showed an increase in water productivity ranged from 14.3% to 44.5% for seed corn and from 34.7% to 52.0% for spring wheat, respectively. Furthermore, adaptive strategies to climate change were recommended for the seed corn and spring wheat, respectively. Our results are expected to provide implications for devising adaptive strategies to changing environments in other arid and irrigation-fed areas.