"Root phenomics for harnessing hidden-half dynamic plasticity under water stress".

Adapting crops to climate-driven water extremes is a cornerstone of agricultural sustainability. Historically overlooked due to phenotyping constraints, root phenes have now emerged as a primary frontier for enhancing crop resilience. We review root architectural and anatomical responses to contrasting water extremes -drought and waterlogging- across major crop species. We examine key root phenes and their associated functions as modulated by developmental and environmental cues. Non-destructive longitudinal root phenomics offers an unprecedented view of the adaptive plastic responses that underpin tolerance to water stress by capturing their spatiotemporal dynamics. We discuss the challenges in root phenomics due to methodological trade-offs in resolution, throughput, and data analysis. We argue that a robust framework for root trait discovery can be achieved by integrating strategic trait selection with modelling and Artificial Intelligence (AI). This will enable scaling root insights across varied environments by bridging the lab-field gap and across phenotyping platforms. Finally, we emphasise the importance of spatial and temporal monitoring of root dynamics during stress and recovery, both critical components of stress adaptation, that are now accessible through non-destructive phenotyping. The next frontier for root research lies in uncovering the genetic architecture behind these dynamics to enhance crop resilience.