Improving crop drought resistance is crucial for mitigating the impacts of drought stress on crop production worldwide. For a long time, deep roots have been considered one of the most effective ways to facilitate full utilization of subsoil water when topsoil water is not available under drought conditions. However, a deeper root system is not always associated with a higher drought resistance. Therefore, gaining a comprehensive understanding of deep roots would be beneficial for improving drought resistance. In this review, we first systematically outline the deep root functions influencing crop drought resistance. We propose that a deeper root system with low metabolic costs can benefit drought resistance, particularly when subsoil water exists in water-limited environments. Then, we overview the methods, including crop breeding and field managements, to increase the drought resistance by regulating deep roots. Third, we review the methods for phenotyping deep roots directly and indirectly. High-throughput deep root phenotyping methods in the field are highly needed, and electromagnetic technologies are promising to satisfy this need in the future. Looking forward, we provide some perspectives on studying deep root systems.

提高作物抗旱性对于减轻干旱胁迫对全球作物生产的影响至关重要。长期以来，深根一直被认为是促进充分利用地下水的最有效方法之一。在干旱条件下无法获得表土水。然而，更深的根系并不总是与更高的抗旱性相关。因此，全面了解深根有利于提高抗旱性。在这篇综述中，我们首先系统地概述了影响作物抗旱性的深根功能。我们建议具有低代谢成本的更深的根系可以有利于抗旱性，特别是当地下水存在于水受限的环境中时。然后，我们概述了通过调节深根来提高抗旱性的方法，包括作物育种和田间管理。第三，我们回顾了直接和间接表型深根的方法。非常需要该领域的高通量深根表型方法，电磁技术有望在未来满足这一需求。展望未来，我们提供了一些关于研究深根系统的观点。