Department of Environmental Systems Science, Physics of Soils and Terrestrial Ecosystems, Institute of Terrestrial Ecosystems, ETH Zürich, Universitätsstrasse 16, 8092, Zurich, Switzerland.
Root-Soil Interactions, School of Life Sciences, Technical University of Munich, D-85354, Freising, Germany.
New Phytol. 2023 Dec;240(6):2484-2497. doi: 10.1111/nph.19144. Epub 2023 Jul 31.
The effect of root hairs on water uptake remains controversial. In particular, the key root hair and soil parameters that determine their importance have been elusive. We grew maize plants (Zea mays) in microcosms and scanned them using synchrotron-based X-ray computed microtomography. By means of image-based modelling, we investigated the parameters determining the effectiveness of root hairs in root water uptake. We explicitly accounted for rhizosphere features (e.g. root-soil contact and pore structure) and took root hair shrinkage of dehydrated root hairs into consideration. Our model suggests that > 85% of the variance in root water uptake is explained by the hair-induced increase in root-soil contact. In dry soil conditions, root hair shrinkage reduces the impact of hairs substantially. We conclude that the effectiveness of root hairs on root water uptake is determined by the hair-induced increase in root-soil contact and root hair shrinkage. Although the latter clearly reduces the effect of hairs on water uptake, our model still indicated facilitation of water uptake by root hairs at soil matric potentials from -1 to -0.1 MPa. Our findings provide new avenues towards a mechanistic understanding of the role of root hairs on water uptake.
根毛对水分吸收的影响仍然存在争议。特别是，决定根毛重要性的关键根毛和土壤参数一直难以捉摸。我们在微环境中种植玉米植株（Zea mays），并使用基于同步加速器的 X 射线计算微断层扫描对其进行扫描。通过基于图像的建模，我们研究了决定根毛在根系水分吸收中有效性的参数。我们明确考虑了根际特征（例如根-土接触和孔隙结构），并考虑了脱水根毛的根毛收缩。我们的模型表明，根毛诱导的根-土接触增加解释了根系水分吸收方差的>85%。在干燥的土壤条件下，根毛收缩会大大降低根毛的影响。我们得出的结论是，根毛对根系水分吸收的有效性取决于根毛诱导的根-土接触和根毛收缩。尽管后者显然会降低根毛对水分吸收的影响，但我们的模型仍表明，在土壤基质势从-1 到-0.1 MPa 的情况下，根毛有助于水分吸收。我们的研究结果为理解根毛在水分吸收中的作用提供了新的途径。
