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Drought and nutrient limitations adversely affect crop yields, with below-ground traits enhancing crop production in these resource-poor environments. This review explores the interacting biological, chemical and physical factors that determine rhizosheath (soil adhering to the root system) development, and its influence on plant water uptake and phosphorus acquisition in dry soils. Identification of quantitative trait loci for rhizosheath development indicate it is genetically determined, but the microbial community also directly (polysaccharide exudation) and indirectly (altered root hair development) affect its extent. Plants with longer and denser root hairs had greater rhizosheath development and increased P uptake efficiency. Moreover, enhanced rhizosheath formation maintains contact at the rootsoil interface thereby assisting water uptake from drying soil, consequently improving plant survival in droughted environments. Nevertheless, it can be difficult to determine if rhizosheath development is a cause or consequence of improved plant adaptation to dry and nutrient-depleted soils. Does rhizosheath development directly enhance plant water and phosphorus use, or do other tolerance mechanisms allow plants to invest more resources in rhizosheath development? Much more work is required on the interacting genetic, physical, biochemical and microbial mechanisms that determine rhizosheath development, to demonstrate that selection for rhizosheath development is a viable crop improvement strategy. K E Y W O R D S alternate wetting and drying cycles, drought, QTLs, water uptake 1 | INTRODUCTIONClimate change has generally increased the frequency and intensity of drought in the world's arable soils, thereby restricting crop yields (Fahad et al., 2017;Potopová et al., 2016). Crop productivity is also influenced by its nutritional status such as phosphorus (P) deficiency, which alters plant physiological functions and limits yields (Bista et al., 2018; Farooq et al., 2021). Drought stress and P deficiency frequently co-occur since any restriction in transpiration limits the uptake of water and nutrients, and may cause agronomic effects that

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