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Duddek P, Carminati A, Koebernick N, Ohmann L, Lovric G, Delzon S, Rodriguez‐Dominguez CM, King A, Ahmed MA. The impact of drought-induced root and root hair shrinkage on root-soil contact. Plant Physiol 2022; 189:1232-1236. [PMID: 35325215 PMCID: PMC9237671 DOI: 10.1093/plphys/kiac144] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/05/2022] [Indexed: 05/16/2023]
Abstract
Although root hairs significantly increased root–soil contact, in maize, their shrinkage during soil drying is initiated at relatively high soil matric potentials (between −10 and −310 kPa).
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Affiliation(s)
- Patrick Duddek
- Physics of Soils and Terrestrial Ecosystems, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, ETH Zürich, Universitätsstrasse 16, 8092 Zurich, Switzerland
- Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitätstrasse 30, 95447 Bayreuth, Germany
| | - Andrea Carminati
- Physics of Soils and Terrestrial Ecosystems, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, ETH Zürich, Universitätsstrasse 16, 8092 Zurich, Switzerland
| | - Nicolai Koebernick
- Soil Science and Soil Protection, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120 Halle (Saale), Germany
| | - Luise Ohmann
- Department of Soil System Science, Helmholtz Centre for Environmental Research, Theodor-Lieser-Str. 4, 06120 Halle (Saale), Germany
| | - Goran Lovric
- Swiss Light Source, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Sylvain Delzon
- BIOGECO, INRA, Univ. Bordeaux, Allée Geoffroy St-Hilaire, 33615 Pessac, France
| | | | - Andrew King
- Synchrotron SOLEIL, L’Orme des Merisiers, 91192 Gif-sur-Yvette Cedex, France
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Marin M, Hallett PD, Feeney DS, Brown LK, Naveed M, Koebernick N, Ruiz S, Bengough AG, Roose T, George TS. Impact of root hairs on microscale soil physical properties in the field. Plant Soil 2022; 476:491-509. [PMID: 35992246 PMCID: PMC9381483 DOI: 10.1007/s11104-022-05530-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
AIMS Recent laboratory studies revealed that root hairs may alter soil physical behaviour, influencing soil porosity and water retention on the small scale. However, the results are not consistent, and it is not known if structural changes at the small-scale have impacts at larger scales. Therefore, we evaluated the potential effects of root hairs on soil hydro-mechanical properties in the field using rhizosphere-scale physical measurements. METHODS Changes in soil water retention properties as well as mechanical and hydraulic characteristics were monitored in both silt loam and sandy loam soils. Measurements were taken from plant establishment to harvesting in field trials, comparing three barley genotypes representing distinct phenotypic categories in relation to root hair length. Soil hardness and elasticity were measured using a 3-mm-diameter spherical indenter, while water sorptivity and repellency were measured using a miniaturized infiltrometer with a 0.4-mm tip radius. RESULTS Over the growing season, plants induced changes in the soil water retention properties, with the plant available water increasing by 21%. Both soil hardness (P = 0.031) and elasticity (P = 0.048) decreased significantly in the presence of root hairs in silt loam soil, by 50% and 36%, respectively. Root hairs also led to significantly smaller water repellency (P = 0.007) in sandy loam soil vegetated with the hairy genotype (-49%) compared to the hairless mutant. CONCLUSIONS Breeding of cash crops for improved soil conditions could be achieved by selecting root phenotypes that ameliorate soil physical properties and therefore contribute to increased soil health. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s11104-022-05530-1.
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Affiliation(s)
- M. Marin
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU UK
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
| | - P. D. Hallett
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU UK
| | - D. S. Feeney
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
- School of Science and Engineering, University of Dundee, Dundee, DD1 4HN UK
| | - L. K. Brown
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
| | - M. Naveed
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU UK
- Present Address: School of Computing and Engineering, University of West London, London, W5 5RF UK
| | - N. Koebernick
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ UK
- Present Address: Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, 06108 Halle (Saale), Germany
| | - S. Ruiz
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ UK
| | - A. G. Bengough
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
- School of Science and Engineering, University of Dundee, Dundee, DD1 4HN UK
| | - T. Roose
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ UK
| | - T. S. George
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
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Marin M, Feeney DS, Brown LK, Naveed M, Ruiz S, Koebernick N, Bengough AG, Hallett PD, Roose T, Puértolas J, Dodd IC, George TS. Significance of root hairs for plant performance under contrasting field conditions and water deficit. Ann Bot 2021; 128:1-16. [PMID: 33038211 PMCID: PMC8318266 DOI: 10.1093/aob/mcaa181] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 10/07/2020] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Previous laboratory studies have suggested selection for root hair traits in future crop breeding to improve resource use efficiency and stress tolerance. However, data on the interplay between root hairs and open-field systems, under contrasting soils and climate conditions, are limited. As such, this study aims to experimentally elucidate some of the impacts that root hairs have on plant performance on a field scale. METHODS A field experiment was set up in Scotland for two consecutive years, under contrasting climate conditions and different soil textures (i.e. clay loam vs. sandy loam). Five barley (Hordeum vulgare) genotypes exhibiting variation in root hair length and density were used in the study. Root hair length, density and rhizosheath weight were measured at several growth stages, as well as shoot biomass, plant water status, shoot phosphorus (P) accumulation and grain yield. KEY RESULTS Measurements of root hair density, length and its correlation with rhizosheath weight highlighted trait robustness in the field under variable environmental conditions, although significant variations were found between soil textures as the growing season progressed. Root hairs did not confer a notable advantage to barley under optimal conditions, but under soil water deficit root hairs enhanced plant water status and stress tolerance resulting in a less negative leaf water potential and lower leaf abscisic acid concentration, while promoting shoot P accumulation. Furthermore, the presence of root hairs did not decrease yield under optimal conditions, while root hairs enhanced yield stability under drought. CONCLUSIONS Selecting for beneficial root hair traits can enhance yield stability without diminishing yield potential, overcoming the breeder's dilemma of trying to simultaneously enhance both productivity and resilience. Therefore, the maintenance or enhancement of root hairs can represent a key trait for breeding the next generation of crops for improved drought tolerance in relation to climate change.
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Affiliation(s)
- M Marin
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
- The James Hutton Institute, Invergowrie, Dundee, UK
| | - D S Feeney
- The James Hutton Institute, Invergowrie, Dundee, UK
- School of Science and Engineering, University of Dundee, Dundee, UK
| | - L K Brown
- The James Hutton Institute, Invergowrie, Dundee, UK
| | - M Naveed
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
- School of Computing and Engineering, University of West London, London, UK
| | - S Ruiz
- School of Engineering, University of Southampton, Southampton, UK
| | - N Koebernick
- School of Engineering, University of Southampton, Southampton, UK
- Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - A G Bengough
- The James Hutton Institute, Invergowrie, Dundee, UK
- School of Science and Engineering, University of Dundee, Dundee, UK
| | - P D Hallett
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - T Roose
- School of Engineering, University of Southampton, Southampton, UK
| | - J Puértolas
- The Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - I C Dodd
- The Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - T S George
- The James Hutton Institute, Invergowrie, Dundee, UK
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Scotson CP, van Veelen A, Williams KA, Koebernick N, McKay Fletcher D, Roose T. Developing a system for in vivo imaging of maize roots containing iodinated contrast media in soil using synchrotron XCT and XRF. Plant Soil 2020; 460:647-665. [PMID: 34720206 PMCID: PMC8550435 DOI: 10.1007/s11104-020-04784-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 11/25/2020] [Indexed: 06/13/2023]
Abstract
AIMS We sought to develop a novel experimental system which enabled application of iodinated contrast media to in vivo plant roots intact in soil and was compatible with time-resolved synchrotron X-ray computed tomography imaging. The system was developed to overcome issues of low contrast to noise within X-ray computed tomography images of plant roots and soil environments, the latter of which can complicate image processing and result in the loss of anatomical information. METHODS To demonstrate the efficacy of the system we employ the novel use of both synchrotron X-ray computed tomography and synchrotron X-ray fluorescence mapping to capture the translocation of the contrast media through root vasculature into the leaves. RESULTS With the application of contrast media we identify fluid flow in root vasculature and visualise anatomical features, which are otherwise often only observable in ex vivo microscopy, including: the xylem, metaxylem, pith, fibres in aerenchyma and leaf venation. We are also able to observe interactions between aerenchyma cross sectional area and solute transport in the root vasculature with depth. CONCLUSIONS Our novel system was capable of successfully delivering sufficient contrast media into root and leaf tissues such that anatomical features could be visualised and internal fluid transport observed. We propose that our system could be used in future to study internal plant transport mechanisms and parameterise models for fluid flow in plants. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s11104-020-04784-x.
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Affiliation(s)
- Callum P. Scotson
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, SO17 1BJ UK
| | - Arjen van Veelen
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, SO17 1BJ UK
- Material Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA
| | - Katherine A. Williams
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, SO17 1BJ UK
| | - Nicolai Koebernick
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, SO17 1BJ UK
- Soil Science and Soil Protection, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120 Halle (Saale), Germany
| | - Dan McKay Fletcher
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, SO17 1BJ UK
| | - Tiina Roose
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, SO17 1BJ UK
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Blaser SRGA, Koebernick N, Spott O, Thiel E, Vetterlein D. Dynamics of localised nitrogen supply and relevance for root growth of Vicia faba ('Fuego') and Hordeum vulgare ('Marthe') in soil. Sci Rep 2020; 10:15776. [PMID: 32978408 PMCID: PMC7519116 DOI: 10.1038/s41598-020-72140-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 08/17/2020] [Indexed: 11/29/2022] Open
Abstract
Root growth responds to local differences in N-form and concentration. This is known for artificial systems and assumed to be valid in soil. The purpose of this study is to challenge this assumption for soil mesocosms locally supplied with urea with and without nitrification inhibitor. Soil column experiments with Vicia faba ('Fuego') and Hordeum vulgare ('Marthe') were performed to investigate soil solution chemistry and root growth response of these two species with contrasting root architectures to the different N-supply simultaneously. Root growth was analysed over time and separately for the fertiliser layer and the areas above and below with X-ray CT (via region growing) and WinRHIZO. Additionally, NO3- and NH4+ in soil and soil solution were analysed. In Vicia faba, no pronounced differences were observed, although CT analysis indicated different root soil exploration for high NH4+. In Hordeum vulgare, high NO3- inhibited lateral root growth while high NH4+ stimulated the formation of first order laterals. The growth response to locally distributed N-forms in soil is species specific and less pronounced than in artificial systems. The combination of soil solution studies and non-invasive imaging of root growth can substantially improve the mechanistic understanding of root responses to different N-forms in soil.
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Affiliation(s)
- Sebastian R G A Blaser
- Department of Soil System Science, Helmholtz-Centre for Environmental Research GmbH - UFZ, Theodor-Lieser-Str. 4, 06120, Halle (Saale), Germany.
| | - Nicolai Koebernick
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120, Halle (Saale), Germany
| | - Oliver Spott
- Agricultural Application Research, SKW Piesteritz GmbH, Am Wieseneck 7, 04451, Cunnersdorf, Germany
| | - Enrico Thiel
- Agricultural Application Research, SKW Piesteritz GmbH, Am Wieseneck 7, 04451, Cunnersdorf, Germany
| | - Doris Vetterlein
- Department of Soil System Science, Helmholtz-Centre for Environmental Research GmbH - UFZ, Theodor-Lieser-Str. 4, 06120, Halle (Saale), Germany
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120, Halle (Saale), Germany
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van Veelen A, Koebernick N, Scotson CS, McKay-Fletcher D, Huthwelker T, Borca CN, Mosselmans JFW, Roose T. Root-induced soil deformation influences Fe, S and P: rhizosphere chemistry investigated using synchrotron XRF and XANES. New Phytol 2020; 225:1476-1490. [PMID: 31591727 DOI: 10.1111/nph.16242] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 09/27/2019] [Indexed: 05/10/2023]
Abstract
Rhizosphere soil has distinct physical and chemical properties from bulk soil. However, besides root-induced physical changes, chemical changes have not been extensively measured in situ on the pore scale. In this study, we couple structural information, previously obtained using synchrotron X-ray computed tomography (XCT), with synchrotron X-ray fluorescence microscopy (XRF) and X-ray absorption near-edge structure (XANES) to unravel chemical changes induced by plant roots. Our results suggest that iron (Fe) and sulfur (S) increase notably in the direct vicinity of the root via solubilization and microbial activity. XANES further shows that Fe is slightly reduced, S is increasingly transformed into sulfate (SO42- ) and phosphorus (P) is increasingly adsorbed to humic substances in this enrichment zone. In addition, the ferrihydrite fraction decreases drastically, suggesting the preferential dissolution and the formation of more stable Fe oxides. Additionally, the increased transformation of organic S to sulfate indicates that the microbial activity in this zone is increased. These changes in soil chemistry correspond to the soil compaction zone as previously measured via XCT. The fact that these changes are colocated near the root and the compaction zone suggests that decreased permeability as a result of soil structural changes acts as a barrier creating a zone with increased rhizosphere chemical interactions via surface-mediated processes, microbial activity and acidification.
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Affiliation(s)
- Arjen van Veelen
- Bioengineering Sciences Research Group, Faculty of Engineering and Physical Sciences, School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Nicolai Koebernick
- Bioengineering Sciences Research Group, Faculty of Engineering and Physical Sciences, School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Callum S Scotson
- Bioengineering Sciences Research Group, Faculty of Engineering and Physical Sciences, School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Daniel McKay-Fletcher
- Bioengineering Sciences Research Group, Faculty of Engineering and Physical Sciences, School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Thomas Huthwelker
- Paul Scherrer Institute, Swiss Light Source, Villigen, 5232, Switzerland
| | - Camelia N Borca
- Paul Scherrer Institute, Swiss Light Source, Villigen, 5232, Switzerland
| | - J Fred W Mosselmans
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Tiina Roose
- Bioengineering Sciences Research Group, Faculty of Engineering and Physical Sciences, School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ, UK
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7
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Ruiz S, Koebernick N, Duncan S, Fletcher DM, Scotson C, Boghi A, Marin M, Bengough AG, George TS, Brown LK, Hallett PD, Roose T. Significance of root hairs at the field scale - modelling root water and phosphorus uptake under different field conditions. Plant Soil 2019; 447:281-304. [PMID: 32214504 PMCID: PMC7062663 DOI: 10.1007/s11104-019-04308-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 09/13/2019] [Indexed: 05/22/2023]
Abstract
ABSTRACT BACKGROUND AND AIMS Root hairs play a significant role in phosphorus (P) extraction at the pore scale. However, their importance at the field scale remains poorly understood. METHODS This study uses a continuum model to explore the impact of root hairs on the large-scale uptake of P, comparing root hair influence under different agricultural scenarios. High vs low and constant vs decaying P concentrations down the soil profile are considered, along with early vs late precipitation scenarios. RESULTS Simulation results suggest root hairs accounted for 50% of total P uptake by plants. Furthermore, a delayed initiation time of precipitation potentially limits the P uptake rate by over 50% depending on the growth period. Despite the large differences in the uptake rate, changes in the soil P concentration in the domain due to root solute uptake remains marginal when considering a single growth season. However, over the duration of 6 years, simulation results showed that noticeable differences arise over time. CONCLUSION Root hairs are critical to P capture, with uptake efficiency potentially enhanced by coordinating irrigation with P application during earlier growth stages of crops.
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Affiliation(s)
- S Ruiz
- 1Bioengineering Science Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO17 1BJ UK
| | - N Koebernick
- 1Bioengineering Science Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO17 1BJ UK
- 5Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Universitaetplatz 10, 06108 Halle (Saale), Germany
| | - S Duncan
- 1Bioengineering Science Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO17 1BJ UK
| | - D McKay Fletcher
- 1Bioengineering Science Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO17 1BJ UK
| | - C Scotson
- 1Bioengineering Science Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO17 1BJ UK
| | - A Boghi
- 1Bioengineering Science Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO17 1BJ UK
| | - M Marin
- 2School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU UK
| | - A G Bengough
- 3Ecological Sciences Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
- 4School of Science and Engineering, University of Dundee, Dundee, DD1 4HN UK
| | - T S George
- 3Ecological Sciences Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
| | - L K Brown
- 3Ecological Sciences Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
| | - P D Hallett
- 2School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU UK
| | - T Roose
- 1Bioengineering Science Research Group, Department of Mechanical Engineering, School of Engineering, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO17 1BJ UK
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8
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Koebernick N, Daly KR, Keyes SD, Bengough AG, Brown LK, Cooper LJ, George TS, Hallett PD, Naveed M, Raffan A, Roose T. Imaging microstructure of the barley rhizosphere: particle packing and root hair influences. New Phytol 2019; 221:1878-1889. [PMID: 30289555 DOI: 10.1111/nph.15516] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 09/23/2018] [Indexed: 05/10/2023]
Abstract
Soil adjacent to roots has distinct structural and physical properties from bulk soil, affecting water and solute acquisition by plants. Detailed knowledge on how root activity and traits such as root hairs affect the three-dimensional pore structure at a fine scale is scarce and often contradictory. Roots of hairless barley (Hordeum vulgare L. cv Optic) mutant (NRH) and its wildtype (WT) parent were grown in tubes of sieved (<250 μm) sandy loam soil under two different water regimes. The tubes were scanned by synchrotron-based X-ray computed tomography to visualise pore structure at the soil-root interface. Pore volume fraction and pore size distribution were analysed vs distance within 1 mm of the root surface. Less dense packing of particles at the root surface was hypothesised to cause the observed increased pore volume fraction immediately next to the epidermis. The pore size distribution was narrower due to a decreased fraction of larger pores. There were no statistically significant differences in pore structure between genotypes or moisture conditions. A model is proposed that describes the variation in porosity near roots taking into account soil compaction and the surface effect at the root surface.
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Affiliation(s)
- Nicolai Koebernick
- Bioengineering Sciences Research Group, Engineering Sciences Academic Unit, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK
- Soil Science and Soil Protection, Martin Luther University Halle-Wittenberg, von-Seckendoff-Platz 3, 06120, Halle (Saale), Germany
| | - Keith R Daly
- Bioengineering Sciences Research Group, Engineering Sciences Academic Unit, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK
| | - Samuel D Keyes
- Bioengineering Sciences Research Group, Engineering Sciences Academic Unit, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK
| | - Anthony G Bengough
- Ecological Sciences Group, The James Hutton Institute, Dundee, DD2 5DA, UK
- School of Science and Engineering, University of Dundee, Dundee, DD1 4HN, UK
| | - Lawrie K Brown
- Ecological Sciences Group, The James Hutton Institute, Dundee, DD2 5DA, UK
| | - Laura J Cooper
- Bioengineering Sciences Research Group, Engineering Sciences Academic Unit, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK
- Mathematics Institute, University of Warwick, Warwick, CV4 7AL, UK
| | - Timothy S George
- Ecological Sciences Group, The James Hutton Institute, Dundee, DD2 5DA, UK
| | - Paul D Hallett
- Institute of Biological and Environmental Science, University of Aberdeen, Aberdeen, AB24 3FX, UK
| | - Muhammad Naveed
- Institute of Biological and Environmental Science, University of Aberdeen, Aberdeen, AB24 3FX, UK
- School of Computing and Engineering, University of West London, London, W5 5RF, UK
| | - Annette Raffan
- Institute of Biological and Environmental Science, University of Aberdeen, Aberdeen, AB24 3FX, UK
| | - Tiina Roose
- Bioengineering Sciences Research Group, Engineering Sciences Academic Unit, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK
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9
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Naveed M, Ahmed MA, Benard P, Brown LK, George TS, Bengough AG, Roose T, Koebernick N, Hallett PD. Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis. Plant Soil 2019; 437:65-81. [PMID: 31007286 PMCID: PMC6447521 DOI: 10.1007/s11104-019-03939-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 01/08/2019] [Indexed: 06/01/2023]
Abstract
AIMS Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depends on their physicochemical characteristics and origin. METHODS Surface tension and viscosity of the exudate solutions were measured using the Du Noüy ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g-1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential. RESULTS Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching wilting point at -1500 kPa matric potential. CONCLUSIONS Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis.
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Affiliation(s)
- M. Naveed
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU UK
- School of Computing and Engineering, University of West London, Ealing London, W5 5RF UK
| | - M. A. Ahmed
- Faculty of Biology, Chemistry and Earth Sciences, University of Bayreuth, Bayreuth, Germany
| | - P. Benard
- Faculty of Biology, Chemistry and Earth Sciences, University of Bayreuth, Bayreuth, Germany
| | - L. K. Brown
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
| | - T. S. George
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
| | - A. G. Bengough
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA UK
- School of Science and Engineering, University of Dundee, Dundee, DD1 4HN UK
| | - T. Roose
- Faculty of Engineering and Environment, University of Southampton, Southampton, SO17 1BJ UK
| | - N. Koebernick
- Faculty of Engineering and Environment, University of Southampton, Southampton, SO17 1BJ UK
| | - P. D. Hallett
- School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 3UU UK
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10
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Cooper LJ, Daly KR, Hallett PD, Koebernick N, George TS, Roose T. The effect of root exudates on rhizosphere water dynamics. Proc Math Phys Eng Sci 2018; 474:20180149. [PMID: 30333700 PMCID: PMC6189581 DOI: 10.1098/rspa.2018.0149] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 08/03/2018] [Indexed: 11/12/2022] Open
Abstract
Most water and nutrients essential for plant growth travel across a thin zone of soil at the interface between roots and soil, termed the rhizosphere. Chemicals exuded by plant roots can alter the fluid properties, such as viscosity, of the water phase, potentially with impacts on plant productivity and stress tolerance. In this paper, we study the effects of plant exudates on the macroscale properties of water movement in soil. Our starting point is a microscale description of two fluid flow and exudate diffusion in a periodic geometry composed from a regular repetition of a unit cell. Using multiscale homogenization theory, we derive a coupled set of equations that describe the movement of air and water, and the diffusion of plant exudates on the macroscale. These equations are parametrized by a set of cell problems that capture the flow behaviour. The mathematical steps are validated by comparing the resulting homogenized equations to the original pore scale equations, and we show that the difference between the two models is ≲7% for eight cells. The resulting equations provide a computationally efficient method to study plant-soil interactions. This will increase our ability to predict how contrasting root exudation patterns may influence crop uptake of water and nutrients.
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Affiliation(s)
- L. J. Cooper
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - K. R. Daly
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - P. D. Hallett
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - N. Koebernick
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - T. S. George
- The James Hutton Institute, Invergowrie, Dundee, UK
| | - T. Roose
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
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11
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Keyes SD, Cooper L, Duncan S, Koebernick N, McKay Fletcher DM, Scotson CP, van Veelen A, Sinclair I, Roose T. Measurement of micro-scale soil deformation around roots using four-dimensional synchrotron tomography and image correlation. J R Soc Interface 2018; 14:rsif.2017.0560. [PMID: 29118113 DOI: 10.1098/rsif.2017.0560] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 10/13/2017] [Indexed: 01/19/2023] Open
Abstract
This study applied time lapse (four-dimensional) synchrotron X-ray computed tomography to observe micro-scale interactions between plant roots and soil. Functionally contrasting maize root tips were repeatedly imaged during ingress into soil columns of varying water content and compaction. This yielded sequences of three-dimensional densiometric data, representing time-resolved geometric soil and root configurations at the micronmetre scale. These data were used as inputs for two full-field kinematic quantification methods, which enabled the analysis of three-dimensional soil deformation around elongating roots. Discrete object tracking was used to track rigid mineral grains, while continuum digital volume correlation was used to track grey-level patterns within local sub-volumes. These techniques both allowed full-field soil displacements to be quantified at an intra-rhizosphere spatial sampling scale of less than 300 µm. Significant differences in deformation mechanisms were identified around different phenotypes under different soil conditions. A uniquely strong contrast was observed between intact and de-capped roots grown in dry, compacted soil. This provides evidence that functional traits of the root cap significantly reduce the amount of soil disturbance per unit of root elongation, with this effect being particularly significant in drier soil.
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Affiliation(s)
- S D Keyes
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - L Cooper
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - S Duncan
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - N Koebernick
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - D M McKay Fletcher
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - C P Scotson
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - A van Veelen
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - I Sinclair
- Materials Engineering Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - T Roose
- Bioengineering Sciences Research Group, Department of Mechanical Engineering, Faculty of Engineering and Environment, University of Southampton, University Road, Southampton SO17 1BJ, UK
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12
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Cooper LJ, Daly KR, Hallett PD, Naveed M, Koebernick N, Bengough AG, George TS, Roose T. Fluid flow in porous media using image-based modelling to parametrize Richards' equation. Proc Math Phys Eng Sci 2017; 473:20170178. [PMID: 29225490 PMCID: PMC5719621 DOI: 10.1098/rspa.2017.0178] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 10/20/2017] [Indexed: 11/12/2022] Open
Abstract
The parameters in Richards' equation are usually calculated from experimentally measured values of the soil-water characteristic curve and saturated hydraulic conductivity. The complex pore structures that often occur in porous media complicate such parametrization due to hysteresis between wetting and drying and the effects of tortuosity. Rather than estimate the parameters in Richards' equation from these indirect measurements, image-based modelling is used to investigate the relationship between the pore structure and the parameters. A three-dimensional, X-ray computed tomography image stack of a soil sample with voxel resolution of 6 μm has been used to create a computational mesh. The Cahn-Hilliard-Stokes equations for two-fluid flow, in this case water and air, were applied to this mesh and solved using the finite-element method in COMSOL Multiphysics. The upscaled parameters in Richards' equation are then obtained via homogenization. The effect on the soil-water retention curve due to three different contact angles, 0°, 20° and 60°, was also investigated. The results show that the pore structure affects the properties of the flow on the large scale, and different contact angles can change the parameters for Richards' equation.
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Affiliation(s)
- L J Cooper
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - K R Daly
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - P D Hallett
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK
| | - M Naveed
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK
| | - N Koebernick
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - A G Bengough
- The James Hutton Institute, Invergowrie, Dundee, UK.,School of Science and Engineering, University of Dundee, Dundee, UK
| | - T S George
- The James Hutton Institute, Invergowrie, Dundee, UK
| | - T Roose
- Bioengineering Sciences Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
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13
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Naveed M, Brown LK, Raffan AC, George TS, Bengough AG, Roose T, Sinclair I, Koebernick N, Cooper L, Hackett CA, Hallett PD. Plant exudates may stabilize or weaken soil depending on species, origin and time. Eur J Soil Sci 2017; 68:806-816. [PMID: 29263712 PMCID: PMC5726377 DOI: 10.1111/ejss.12487] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 09/11/2017] [Accepted: 09/13/2017] [Indexed: 05/07/2023]
Abstract
We hypothesized that plant exudates could either gel or disperse soil depending on their chemical characteristics. Barley (Hordeum vulgare L. cv. Optic) and maize (Zea mays L. cv. Freya) root exudates were collected using an aerated hydroponic method and compared with chia (Salvia hispanica L.) seed exudate, a commonly used root exudate analogue. Sandy loam soil was passed through a 500-μm mesh and treated with each exudate at a concentration of 4.6 mg exudate g-1 dry soil. Two sets of soil samples were prepared. One set of treated soil samples was maintained at 4°C to suppress microbial processes. To characterize the effect of decomposition, the second set of samples was incubated at 16°C for 2 weeks at -30 kPa matric potential. Gas chromatography-mass spectrometry (GC-MS) analysis of the exudates showed that barley had the largest organic acid content and chia the largest content of sugars (polysaccharide-derived or free), and maize was in between barley and chia. Yield stress of amended soil samples was measured by an oscillatory strain sweep test with a cone plate rheometer. When microbial decomposition was suppressed at 4°C, yield stress increased 20-fold for chia seed exudate and twofold for maize root exudate compared with the control, whereas for barley root exudate decreased to half. The yield stress after 2 weeks of incubation compared with soil with suppressed microbial decomposition increased by 85% for barley root exudate, but for chia and maize it decreased by 87 and 54%, respectively. Barley root exudation might therefore disperse soil and this could facilitate nutrient release. The maize root and chia seed exudates gelled soil, which could create a more stable soil structure around roots or seeds. HIGHLIGHTS Rheological measurements quantified physical behaviour of plant exudates and effect on soil stabilization.Barley root exudates dispersed soil, which could release nutrients and carbon.Maize root and chia seed exudates had a stabilizing effect on soil.Physical engineering of soil in contact with plant roots depends on the nature and origin of exudates.
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Affiliation(s)
- M. Naveed
- School of Biological SciencesUniversity of AberdeenAberdeenAB24 3UUUK
| | - L. K. Brown
- The James Hutton Institute, InvergowrieDundeeDD2 5DAUK
| | - A. C. Raffan
- School of Biological SciencesUniversity of AberdeenAberdeenAB24 3UUUK
| | - T. S. George
- The James Hutton Institute, InvergowrieDundeeDD2 5DAUK
| | - A. G. Bengough
- The James Hutton Institute, InvergowrieDundeeDD2 5DAUK
- School of Science and EngineeringUniversity of DundeeDundeeDD1 4HNUK
| | - T. Roose
- Faculty of Engineering and EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - I. Sinclair
- Faculty of Engineering and EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - N. Koebernick
- School of Science and EngineeringUniversity of DundeeDundeeDD1 4HNUK
| | - L. Cooper
- School of Science and EngineeringUniversity of DundeeDundeeDD1 4HNUK
| | - C. A. Hackett
- Biomathematics and Statistics Scotland, InvergowrieDundeeDD2 5DAUK
| | - P. D. Hallett
- School of Biological SciencesUniversity of AberdeenAberdeenAB24 3UUUK
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14
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Koebernick N, Daly KR, Keyes SD, George TS, Brown LK, Raffan A, Cooper LJ, Naveed M, Bengough AG, Sinclair I, Hallett PD, Roose T. High-resolution synchrotron imaging shows that root hairs influence rhizosphere soil structure formation. New Phytol 2017; 216:124-135. [PMID: 28758681 PMCID: PMC5601222 DOI: 10.1111/nph.14705] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 06/12/2017] [Indexed: 05/17/2023]
Abstract
In this paper, we provide 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 (c. 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), with and without root hairs, were grown for 8 d in microcosms packed with sandy loam soil at 1.2 g cm-3 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 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.
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Affiliation(s)
- Nicolai Koebernick
- Bioengineering Sciences Research GroupEngineering Sciences Academic UnitFaculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - Keith R. Daly
- Bioengineering Sciences Research GroupEngineering Sciences Academic UnitFaculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - Samuel D. Keyes
- Bioengineering Sciences Research GroupEngineering Sciences Academic UnitFaculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - Timothy S. George
- Ecological Sciences GroupThe James Hutton InstituteInvergowrieDundeeDD2 5DAUK
| | - Lawrie K. Brown
- Ecological Sciences GroupThe James Hutton InstituteInvergowrieDundeeDD2 5DAUK
| | - Annette Raffan
- Institute of Biological and Environmental ScienceUniversity of AberdeenAberdeenAB24 3UUUK
| | - Laura J. Cooper
- Bioengineering Sciences Research GroupEngineering Sciences Academic UnitFaculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - Muhammad Naveed
- Institute of Biological and Environmental ScienceUniversity of AberdeenAberdeenAB24 3UUUK
| | - Anthony G. Bengough
- Ecological Sciences GroupThe James Hutton InstituteInvergowrieDundeeDD2 5DAUK
- School of Science and EngineeringUniversity of DundeeDundeeDD1 4HNUK
| | - Ian Sinclair
- Bioengineering Sciences Research GroupEngineering Sciences Academic UnitFaculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
| | - Paul D. Hallett
- Institute of Biological and Environmental ScienceUniversity of AberdeenAberdeenAB24 3UUUK
| | - Tiina Roose
- Bioengineering Sciences Research GroupEngineering Sciences Academic UnitFaculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonSO17 1BJUK
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15
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Koebernick N, Huber K, Kerkhofs E, Vanderborght J, Javaux M, Vereecken H, Vetterlein D. Unraveling the hydrodynamics of split root water uptake experiments using CT scanned root architectures and three dimensional flow simulations. Front Plant Sci 2015; 6:370. [PMID: 26074935 PMCID: PMC4448007 DOI: 10.3389/fpls.2015.00370] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 05/09/2015] [Indexed: 05/20/2023]
Abstract
Split root experiments have the potential to disentangle water transport in roots and soil, enabling the investigation of the water uptake pattern of a root system. Interpretation of the experimental data assumes that water flow between the split soil compartments does not occur. Another approach to investigate root water uptake is by numerical simulations combining soil and root water flow depending on the parameterization and description of the root system. Our aim is to demonstrate the synergisms that emerge from combining split root experiments with simulations. We show how growing root architectures derived from temporally repeated X-ray CT scanning can be implemented in numerical soil-plant models. Faba beans were grown with and without split layers and exposed to a single drought period during which plant and soil water status were measured. Root architectures were reconstructed from CT scans and used in the model R-SWMS (root-soil water movement and solute transport) to simulate water potentials in soil and roots in 3D as well as water uptake by growing roots in different depths. CT scans revealed that root development was considerably lower with split layers compared to without. This coincided with a reduction of transpiration, stomatal conductance and shoot growth. Simulated predawn water potentials were lower in the presence of split layers. Simulations showed that this was related to an increased resistance to vertical water flow in the soil by the split layers. Comparison between measured and simulated soil water potentials proved that the split layers were not perfectly isolating and that redistribution of water from the lower, wetter compartments to the drier upper compartments took place, thus water losses were not equal to the root water uptake from those compartments. Still, the layers increased the resistance to vertical flow which resulted in lower simulated collar water potentials that led to reduced stomatal conductance and growth.
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Affiliation(s)
- Nicolai Koebernick
- Department of Soil Physics, Helmholtz Centre for Environmental Research (UFZ)Halle, Germany
| | - Katrin Huber
- Agrosphere (IBG-3), Forschungszentrum Jülich GmbHJülich, Germany
- *Correspondence: Katrin Huber, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, D - 52425 Juelich, Germany
| | - Elien Kerkhofs
- Department of Earth and Environmental Sciences, KU LeuvenLeuven, Belgium
| | - Jan Vanderborght
- Agrosphere (IBG-3), Forschungszentrum Jülich GmbHJülich, Germany
- Department of Earth and Environmental Sciences, KU LeuvenLeuven, Belgium
| | - Mathieu Javaux
- Agrosphere (IBG-3), Forschungszentrum Jülich GmbHJülich, Germany
- Earth and Life Institute/Environmental Sciences, Université Catholique de LouvainLouvain-la-Neuve, Belgium
| | - Harry Vereecken
- Agrosphere (IBG-3), Forschungszentrum Jülich GmbHJülich, Germany
| | - Doris Vetterlein
- Department of Soil Physics, Helmholtz Centre for Environmental Research (UFZ)Halle, Germany
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