Water Productivity of Farmland in Response to Changing Environment: A Review

【Objective】 Water productivity in farmland is a comprehensive indicator describing the relationship between agricultural water use and agricultural production; it is the foundation for planning and managing water resources to improve irrigation water use efficiency. Over the past decades, how the water productivity responds to environmental change has become a new research topic. This paper reviews the latest development in this area and its perspective. 【Method】 The analysis is based on the relationship between biomass production and water flow in farmland. We review the current state based on the studies of how stomata controls photosynthesis and transpiration, as well as quantification of water cycling and water productivity in response to environment change. 【Conclusion】 We identify three barriers that need to be broken: ①The mechanisms underlying the integrated transpiration, soil water and groundwater. ②Developing water productivity models that integrate crop growth and water cycling. ③Develop models to simulate response of water productivity to climate change and implementation of water-saving agronomical practices. We also highlight the prospects for future study of water productivity in farmland in response to changing environments.