Water use efficiency across scales: from genes to landscapes

Water scarcity is already set to be one of the main issues of the 21st century, because of competing needs between civil, industrial, and agricultural use. Agriculture is currently the largest user of water, but its share is bound to decrease as societies develop and clearly it needs to become more water efficient. Improving water use efficiency (WUE) at the plant level is important, but translating this at the farm/landscape level presents considerable challenges. As we move up from the scale of cells, organs, and plants to more integrated scales such as plots, fields, farm systems, and landscapes, other factors such as trade-offs need to be considered to try to improve WUE. These include choices of crop variety/species, farm management practices, landscape design, infrastructure development, and ecosystem functions, where human decisions matter. This review is a cross-disciplinary attempt to analyse approaches to addressing WUE at these different scales, including definitions of the metrics of analysis and consideration of trade-offs. The equations we present in this perspectives paper use similar metrics across scales to make them easier to connect and are developed to highlight which levers, at different scales, can improve WUE. We also refer to models operating at these different scales to assess WUE. While our entry point is plants and crops, we scale up the analysis of WUE to farm systems and landscapes. This review considers approaches to improving water use efficiency beyond the whole-plant level, across scales of time and space, from cells, organs, and plants, to fields, farms, and landscapes.

Automated summary

Water scarcity is expected to become a major issue in the 21st century due to competing needs in civil, industrial, and agricultural sectors. Improving water use efficiency at different scales, from plants to landscapes, is crucial to address this issue. Factors such as crop variety, farm management practices, and ecosystem functions must be considered to improve water use efficiency. This interdisciplinary review analyzes approaches to water use efficiency at different scales and considers trade-offs.