Authors:
Dr. Patrick Duddek | ETH Zurich | Switzerland
Prof. Dr. Mutez Ali Ahmed | TU Munich | Germany
Prof. Dr. Mathieu Javaux | Forschungszentrum Juelich/IBG-3 | Germany
Prof. Dr. Jan Vanderborght | Forschungszentrum Juelich/IBG-3 | Germany
Dr. Goran Lovric | Swiss Light Source, Paul Scherrer Institute | Switzerland
Dr. Andrew King | Synchotron SOLEIL | France
Prof. Dr. Andrea Carminati | ETH Zurich | Switzerland
Root hairs have been suggested as a breeding target to improve the crop resilience to drought stress. However, existing experimental studies indicate that the effect of root hairs in water uptake cannot be generalised across soils and plant species. The objective of our study is to gain a mechanistic understanding of the effect of root hairs on water uptake and thus to identify the environmental conditions under which root hairs facilitate root water uptake.
We scanned root segments of maize (Zea Mays L.) grown in a loamy and a sandy soil using synchrotron-based X-ray computed tomography. Based on the collected CT data, we simulated water flow through the soil-root continuum by solving the flow equations numerically. The image-based approach allowed us to account for rhizosphere properties (e.g., root-soil contact) and root hair shrinkage.
Our results show that, under dry soil conditions, root hairs attenuate the soil matric potential gradient across the rhizosphere, leading to a more efficient water extraction compared to a hairless root. Furthermore, the effect of root hairs is determined by soil properties (e.g. soil porosity), root hair traits (e.g. root hair length and density) and the capacity of hairs to remain turgid under drought stress. Compared to densely packed fine textured soils, the effect of hairs is more pronounced in coarse textured soils. This is explained by the larger decrease in hydraulic conductivity as coarse textured soils dry.
In conclusion, our results show that the effect of root hairs is determined by root-soil contact and root hair shrinkage.