In this paper, we provide the first direct evidence of the importance of root hairs on pore structure development at the root-soil interface during the early stage of crop establishment. This was achieved by use of high resolution (~5 µm) synchrotron radiation computed tomography (SRCT) to visualise both the structure of root hairs and the soil pore structure in plant-soil microcosms. Two contrasting genotypes of barley (Hordeum vulgare L.), with and without root hairs, were grown for 8 days in microcosms packedwith sandy loam soil at 1.2 g cm-3 35 dry bulk density. Root hairs were visualised within air filled pore spaces, but not in the fine-textured soil regions. We found that the genotype with root hairs significantly altered the porosity and connectivity of the detectable pore space (> 5 µm) in the rhizosphere, as compared with the no-hair mutants. Both genotypes showed decreasing pore-space between 0.8 mm and 0.1 mm from the root surface. Interestingly the root-hair-bearing genotype had a significantly greater soil pore volume-fraction at the root-soil interface. Effects of pore structure on diffusion and permeability were estimated to be functionally insignificant under saturated conditions when simulated using image based modelling.
L.J.C., N.K., I.S. and T.R. are funded by BBSRC SARISA BB/L025620/1. K.R.D. is funded by ERC 646809DIMR. L.K.B., P.D.H., T.S.G., M.N. and A.R. are funded by BBSRC BB/J00868/1 and A.G.B. is funded by BB/L025825/1. The James Hutton Institute receives financial support from the Rural & Environment Science & Analytical Services Division of the Scottish Government. I.S. and T.R. are also funded by EPSRC EP/M020355/1. T.R. is also funded by ERC 646809DIMR, BBSRC SARIC BB/P004180/1 and NERC NE/L00237/1. The authors acknowledge the use of the I13 beamline at Diamond Light Source, Oxfordshire, UK (session ID: MT9659). We would like to thank beamline scientist Dr Mirian Garcia Fernandez, who provided considerable help during our beamtime. Additionally, Diamond Light Source funded travel for three people. The authors acknowledge the use of the IRIDIS High Performance Computing Facility, and associated support services at the University of Southampton, in the completion of this work.
All data supporting this study are available on request from the University of Southampton repository at https://doi.org/10.5258/soton/d0116.
- image-based modelling
- non-invasive imaging
- root hairs
- soil structure