Root-Type-Specific Water Uptake in Maize across Soil Texture and Moisture Gradients

Abstract. Understanding how distinct root types contribute to water uptake under variable soil conditions is crucial for improving crop water use efficiency. We quantified root water uptake in six-week-old maize grown in sandy or loamy soil under well-watered and water-limited conditions. Time-series neutron radiography combined with deuterated water labelling enabled estimation of effective radial water uptake of crown and seminal roots using a diffusion–convection model.

Plant development responded strongly to the soil environment, with the greatest reductions in transpiration, shoot height, and root length occurring under sandy-dry conditions. Root water uptake patterns varied with soil texture and water availability. Crown roots exhibited pronounced hydraulic plasticity, with radial fluxes approximately threefold higher in sandy than in loamy soil. In contrast, seminal roots showed no impact of soil conditions on root water uptake. Overall, crown roots showed two times higher radial fluxes than seminal roots.

These findings demonstrate how soil texture and moisture interact with root-type-specific hydraulic function, providing insights for breeding and modelling drought-resilient maize.