Water deficit is one of the primary limitations to crop production. Here, we review the role of root and rhizosphere hydraulic processes that affect the ability of a plant to extract water from the soil. Prominent features of rhizosphere hydraulic properties are: root shrinkage, alteration of pore geometry in the rhizosphere, effect of mucilage on water retention, hydraulic conductivity and water repellency, root hairs, and mycorrhiza connecting the root surface to the soil matrix. All these factors are strongly dynamic, changing over time and with soil moisture conditions. Although our understanding of the mechanisms related to these factors has advanced significantly in the last ten years, the relative importance of these rhizosphere processes for the ability of crops to extract water from the soil and better tolerate drought is still largely unclear. We propose that the next research step is to investigate the implications of these rhizosphere processes on crop growth and water use economy and use this knowledge to grow more resilient crops that match to their environment.
Table of contents
2 Principles of water flow in soil and plants
3 Rhizosphere processes relevant for root water uptake
4 Conclusion and future trends