Climate and management impacts on crop growth and evapotranspiration in the North China Plain based on long-term eddy covariance observation

Abstract

Comprehensive understanding of how climate change and cropland management affect crop growth and water consumption is essential but unclear in the North China Plain (NCP) which is one of the major winter wheat and summer maize production regions. By combining an agro-hydrological model with 16-year eddy covariance observation, we quantified the impacts of climatic factors and key management (i.e., sowing date and irrigation) on the trend of key phenological stages, leaf area index (LAI), crop yield, evapotranspiration (ET), and water use efficiency (WUE) at a typical irrigated site in the NCP. We found that the advance of start and end of season was mainly caused by advanced sowing date and rising temperature which also shortened the reproductive phase; however, the growing season length (GSL) was remarkably shortened by advanced sowing date. Although LAI and yield of both crops were increasing, they were mainly negatively affected by rising temperature while slightly promoted by elevated CO2 concentration. LAI and yield of maize were also greatly improved by increasing radiation and irrigation, and wheat's growth was considerably hampered by excessive irrigation. Increasing ET was mainly ascribed to increasing radiation and decreasing humidity, but slightly inhibited by elevated CO2 concentration. Increasing WUE was mainly inhibited by the rising temperature and decreasing humidity while improved slightly by elevated CO2 concentration. Besides, we inferred that increase in LAI, yield, ET, and WUE of wheat is most likely to be attributed to the renewal of cultivars, the delay of key phenological stages, and prolongation of GSL for both crops was also possibly caused by the renewal of cultivars. Our study provided a first comprehensive insight into the long-term coupled variation of crop growth and evapotranspiration in this region.