Quantification of mycorrhizal water uptake via high-resolution on-line water content sensors

The benefits of mycorrhizas for host plants are well-documented across many species. However, experimental evaluations regarding the contribution of hyphae to total water uptake and their bulk flow velocity remain contradictory.

In this study, barley (Hordeum vulgare L. Scarlet) inoculated with Glomus intraradices was grown in a split plant-hyphal chamber separated by a 5 mm air gap. Loamy-silt soil was used to prepare the chambers, and water content sensors were placed in both the plant and hyphal compartments for non-destructive, high-resolution measurements.

Over eight drying periods, followed by repeated watering, a significant decline in water content was observed in the hyphal compartment during each drying period, indicating the ability of hyphae to transfer water to the plant compartment. The difference in water content decline between compartments with and without arbuscular mycorrhizal fungi was highly significant (p < 0.000001). Hyphal contribution to total water uptake was estimated at approximately 20%.

Capacitance sensors, specially designed for plant-hyphal chambers, provided accurate measurements of hyphal water flow, reinforcing the critical role of mycorrhizal hyphae in plant water dynamics.