Aboveground fungal endophyte infection in tall fescue alters rhizosphere chemical, biological, and hydraulic properties in texture-dependent ways

Background and aims Information regarding the influence of endophyte-tall fescue symbiosis on soil hydraulic properties is rare. The hypothesis in this study was that the presence of Epichloë coenophialum in the tall fescue shoot may alter chemical and biological properties of rhizospheric soil and, as a consequence, the soil hydraulic properties and aggregate stability in texture-dependent ways. Methods A greenhouse pot experiment was conducted to characterize the effects of endophyte-tall fescue symbiosis on water repellency and hydraulic properties of the rhizosphere in six soil types. Aggregate water/ethanol sorptivities and water repellency were determined using a tension micro-infiltrometer. Soil organic carbon, hot-water soluble carbohydrates, basal soil respiration and water-dispersible clay as an index of aggregate instability were also measured. Results Endophytic symbiosis greatly enhanced soil organic carbon pools and hot-water soluble carbohydrates, especially for the medium- to fine-textured soils, and decreased the basal soil respiration. Changes in chemical and biological properties of the rhizosphere via endophyte infection and soil type altered the soil water repellency, hydraulic properties, and aggregate stability. Lower water sorptivity (due to hydrophobic coatings) and higher ethanol sorptivity (due to altered pore structure) were responsible for greater water repellency in the rhizosphere of endophyte-infected plants compared to endophyte-free ones. Conclusion Greater sub-critical water repellency, organic carbon, and hot-water soluble carbohydrates induced by endophyte-tall fescue symbiosis could increase aggregate stability of the rhizosphere and facilitate ecosystem restoration in degraded arid lands.