Wheat genotypic variation in root architecture modifies soil pore structure and hydraulic properties

Root-driven modification of soil hydraulic properties may influence crop water availability and resilience under climatic variability, yet genotype-specific effects on rhizosphere hydrology remain poorly understood.This study examined how contrasting root architectures of four wheat genotypes, two modern cultivars (Paragon, Bologna) and two landraces (Watkins 238, Senatore Cappelli), modify soil hydraulic behaviour under field conditions. Baseline (pre-sowing), bulk (fallow), and rhizosphere soils were characterised for water retention, unsaturated hydraulic conductivity, and pore size distributions derived from fitted retention curves. Root morphological traits were quantified using crown imaging and root scanning.Genotypes differed markedly in both root traits and their associated hydraulic responses. Paragon, Watkins 238, and Senatore Cappelli exhibited bimodal pore size distributions, characterised by two peaks in the pore radius probability density function, whereas Bologna, baseline, and bulk soil displayed unimodal behaviour with a single dominant pore domain. Watkins 238 achieved the most significant improvement in hydraulic properties, increasing plant-available water to 0.21 m3 m−3 (vs. 0.15 m3 m−3 in baseline), driven by a lower permanent wilting point (0.12 m3 m−3) and higher field capacity (0.34 m3 m−3). Watkins 238 also displayed higher unsaturated conductivity, with hydraulic conductivity at field capacity and wilting point significantly higher than baseline and Bologna, and an area under the K(ψ) curve of 46.1, more than double that of other genotypes.Root network area, root diameter, and branching frequency were significantly correlated with water retention parameters and conductivity metrics (p < 0.05 to p < 0.001), indicating that root systems reshape the pore network and soil hydrological properties. These findings suggest genotype-specific modification of hydraulic processes and highlight opportunities to leverage root traits to enhance water availability and resilience under water-limited conditions.