Non-invasive methods for the investigation of trees’ root system in the urban environment

Complex plant-soil interactions can be visualized and quantified by combined application of different non-invasive imaging techniques. Oxygen, carbon dioxide and pH gradients in the rhizosphere can be observed with fluorescent planar optodes, while neutron radiography detects small-scale heterogeneities in soil moisture and its dynamics. Respiration and exudation rates can vary between roots of different types, such as primary and lateral roots, as well as along single roots among the same plant. The 3D root system architecture is therefore a key information when studying rhizosphere processes. It can be captured in detail with neutron tomography, but so far only for plants grown in small, cylindrical containers.Combined non-invasive imaging of biogeochemical dynamics, soil moisture distribution and 3D root system architecture is a technical challenge. Thin, slab-shaped rhizotrons with relatively large vertical and lateral extension are well suited for optical fluorescence imaging, allowing for spatially extended observation of biogeochemical patterns. This rhizotron geometry is, however, unfavorable for standard 3D tomography due to reconstruction artefacts triggered by insufficient neutron transmission when the long side of the sample is aligned parallel to the beam direction.We therefore applied neutron laminography, a method where the rotational axis is tilted, to measure the root systems of maize and lupine plants grown in slab-shaped glass rhizotrons (length&#160;=&#160;150&#160;mm, width&#160;=&#160;150 mm, depth&#160;=&#160;15 mm) in 3D. In parallel, we investigated rhizosphere oxygen dynamics and pH value via fluorescence imaging and assessed soil moisture distribution with neutron radiography.Neutron laminography enabled the 3D reconstruction of the root systems with a nominal spatial resolution of 100 &#181;m/pixel. Reconstruction quality strongly depended on root-soil contrast and hence soil moisture level. After reconstruction of the root system and co-registration with the fluorescence images, first results indicate that observed oxygen concentrations and pH gradients depend on root type and individual distance of the roots from the planar optode.In conclusion, neutron laminography is a novel 3D imaging method for root-soil systems grown in slab-shaped rhizotrons. The method allows for determining the precise 3D position of individual roots within the rhizotron and can be combined with 2D imaging approaches. Following experiments will address X-ray laminography as a possible attractive further application.

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In vivo imaging and quantification of carbon tracer dynamics in nodulated root systems of pea plants

10.1101/2021.06.23.449643 ◽

2021 ◽

Author(s):

Ralf Metzner ◽

Antonia Chlubek ◽

Jonas Bühler ◽

Daniel Pflugfelder ◽

Ulrich Schurr ◽

...

Keyword(s):

Root System ◽

Carbon Allocation ◽

Three Dimensional ◽

Plant Host ◽

Nitrate Treatment ◽

Non Invasive ◽

Positron Emission ◽

Nodulated Root ◽

Abiotic Stimuli

Legumes associate with root colonizing rhizobia that provide fixed nitrogen to its plant host in exchange for recently fixed carbon. There is a lack in understanding how individual plants modulate carbon allocation to a nodulated root system as a dynamic response to abiotic stimuli. One reason is that most approaches are based on destructive sampling, making quantification of localized carbon allocation dynamics in the root system difficult. We established an experimental workflow for routinely using non-invasive Positron Emission Tomography (PET) to follow the allocation of leaf-supplied 11C tracer towards individual nodules in a three-dimensional (3D) root system of pea (Pisum sativum). Nitrate was used for triggering the shutdown of biological nitrogen fixation (BNF) expected to rapidly affect carbon allocation dynamics in the root-nodule system. This nitrate treatment lead to a reduction of 11C tracer allocation to nodules by 40% - 47% in 5 treated plants while the variation in control plants was less than 11%. The established experimental pipeline enabled for the first time that several plants could consistently be labelled and measured using 11C tracer in a PET approach to quantify C-allocation to individual nodules following a BNF shutdown. This demonstrates the strength of using 11C tracers in a PET approach for non-invasive quantification of dynamic carbon allocation in several growing plants over several days. A major advantage of the approach is the possibility to investigate carbon dynamics in small regions of interest in a 3D system such as nodules in comparison to whole plant development.

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Small scale characterization of vine plant root water uptake via 3D electrical resistivity tomography and Mise-à-la-Masse method

10.5194/hess-2018-238 ◽

2018 ◽

Cited By ~ 1

Author(s):

Benjamin Mary ◽

Luca Peruzzo ◽

Jacopo Boaga ◽

Myriam Schmutz ◽

Yuxin Wu ◽

...

Keyword(s):

Electrical Resistivity ◽

Root System ◽

Field Data ◽

Electrical Resistivity Tomography ◽

Root Zone ◽

Plant Root ◽

Small Scale ◽

Resistivity Tomography ◽

Invasive Approach ◽

Non Invasive

Abstract. The investigation of plant roots is inherently difficult and often neglected. Being out of sight, roots are often out of mind. Still, roots play a key role in the exchange of mass and energy between soil and the atmosphere, let alone the many practical applications in agriculture. In this paper, we propose a method for roots imaging based on the joint use of two electrical non-invasive methods, Electrical Resistivity Tomography (ERT) and Mise-a-la-Masse (MALM). The approach is based on the key assumption that the plant root system acts as an electrically conductive body, so that injecting electrical current in the plant stem will ultimately result in the injection of current in the subsoil through the root system, and particularly through the root terminations via hair roots. Evidence from field data, showing that voltage distribution is very different whether current is injected in the tree stem or in the ground, strongly supports this hypothesis. The proposed procedure involves a stepwise inversion of both ERT and MALM data that ultimately leads to the identification of electrical resistivity distribution, and of the current-injection root distribution in the three-dimensional soil space. This, in turn, is a proxy to the active (hair) root density in the ground. We tested the proposed procedure on synthetic data and, more importantly, on field data collected in vineyard, where the estimated depth of the root zone proved to be in agreement with literature on similar crops. The proposed non-invasive approach is a step forward towards a better quantification of roots structure and functioning.

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PhenoRoots: an inexpensive non-invasive phenotyping system to assess the variability of the root system architecture

Scientia Agricola ◽

10.1590/1678-992x-2018-0420 ◽

2020 ◽

Vol 77 (5) ◽

Cited By ~ 1

Author(s):

Saulo Muniz Martins ◽

Giovani Greigh de Brito ◽

Washington da Conceição Gonçalves ◽

Bruna Mendes Diniz Tripode ◽

Marc Lartaud ◽

...

Keyword(s):

Root System ◽

System Architecture ◽

Root System Architecture ◽

Non Invasive

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Non-invasive imaging of CO2 and O2 concentration reveals hotspots of root respiration

10.5194/egusphere-egu21-13279 ◽

2021 ◽

Author(s):

Sarah Bereswill ◽

Nicole Rudolph-Mohr ◽

Sascha E. Oswald

Keyword(s):

Soil Moisture ◽

Root System ◽

Root Respiration ◽

Pore Space ◽

Gas Diffusion ◽

Cluster Roots ◽

Spatial And Temporal Variability ◽

In Situ Observation ◽

Imaging Method ◽

Non Invasive

Root respiration constitutes a major contribution to the CO2 efflux from vegetated soils. Amongst temperature, soil moisture is a key environmental variable determining respiration in soils, because it affects the amount of oxygen available for respiration as well as the CO2 gas transport within the soil pore space.Non-invasive imaging techniques facilitate the in situ observation of the complex respiration patterns in the rhizosphere. We applied planar optodes (80x100 mm&#178;) to map the CO2 and O2 concentration in the rhizosphere of white lupine plants (Lupinus albus) grown in slab-shaped glass rhizotrons (150x150x15 mm&#179;) in sandy soil under P-deficient conditions. Respiration was measured daily for 19 days after planting at constant soil moisture content as well as during a drying-rewetting experiment, during which soil volumetric water content varied between 0.1 and 0.3 cm&#179; cm-3.During their development, the plants exhibited a heterogeneous spatial pattern of root respiration; the highest CO2-concentrations were measured at the root tips and along younger parts of the root system. Heterogeneity in CO2 and O2 patterns was most pronounced in the drying-rewetting experiment: Distinct hotspots of CO2-release and oxygen consumption emerged 30 to 60 minutes after watering. The hotspot-regions correlated with the location of cluster roots growing close to the optodes, where up to three times increased CO2 concentrations occurred. Overall CO2 concentrations in the bulk soil increased as CO2 accumulated over time as gas diffusion in the wet soil was limited.Our results highlight the strong spatial and temporal variability of root respiration throughout the growth and development of the root system, and particularly in response to an increase in soil moisture. Further experiments aim to combine CO2 and O2 optode measurements with neutron computed laminography, a tomographic imaging method suited to capture the 3D root system architecture of plants grown in laterally extended rhizotrons in order to link root respiration to root branching order, diameter and functional type.

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Multi-frequency electrical impedance tomography as a non-invasive tool to characterize and monitor crop root systems

Biogeosciences ◽

10.5194/bg-14-921-2017 ◽

2017 ◽

Vol 14 (4) ◽

pp. 921-939 ◽

Cited By ~ 22

Author(s):

Maximilian Weigand ◽

Andreas Kemna

Keyword(s):

Root System ◽

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Low Frequency ◽

Root Systems ◽

Impedance Tomography ◽

Electrical Polarization ◽

Non Invasive ◽

Polarization Response ◽

Crop Root

Abstract. A better understanding of root–soil interactions and associated processes is essential in achieving progress in crop breeding and management, prompting the need for high-resolution and non-destructive characterization methods. To date, such methods are still lacking or restricted by technical constraints, in particular the charactization and monitoring of root growth and function in the field. A promising technique in this respect is electrical impedance tomography (EIT), which utilizes low-frequency (< 1 kHz)- electrical conduction- and polarization properties in an imaging framework. It is well established that cells and cell clusters exhibit an electrical polarization response in alternating electric-current fields due to electrical double layers which form at cell membranes. This double layer is directly related to the electrical surface properties of the membrane, which in turn are influenced by nutrient dynamics (fluxes and concentrations on both sides of the membranes). Therefore, it can be assumed that the electrical polarization properties of roots are inherently related to ion uptake and translocation processes in the root systems. We hereby propose broadband (mHz to hundreds of Hz) multi-frequency EIT as a non-invasive methodological approach for the monitoring and physiological, i.e., functional, characterization of crop root systems. The approach combines the spatial-resolution capability of an imaging method with the diagnostic potential of electrical-impedance spectroscopy. The capability of multi-frequency EIT to characterize and monitor crop root systems was investigated in a rhizotron laboratory experiment, in which the root system of oilseed plants was monitored in a water–filled rhizotron, that is, in a nutrient-deprived environment. We found a low-frequency polarization response of the root system, which enabled the successful delineation of its spatial extension. The magnitude of the overall polarization response decreased along with the physiological decay of the root system due to the stress situation. Spectral polarization parameters, as derived from a pixel-based Debye decomposition analysis of the multi-frequency imaging results, reveal systematic changes in the spatial and spectral electrical response of the root system. In particular, quantified mean relaxation times (of the order of 10 ms) indicate changes in the length scales on which the polarization processes took place in the root system, as a response to the prolonged induced stress situation. Our results demonstrate that broadband EIT is a capable, non-invasive method to image root system extension as well as to monitor changes associated with the root physiological processes. Given its applicability on both laboratory and field scales, our results suggest an enormous potential of the method for the structural and functional imaging of root systems for various applications. This particularly holds for the field scale, where corresponding methods are highly desired but to date are lacking.

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Multi-frequency electrical impedance tomography as a non-invasive tool to characterize and monitor crop root systems

10.5194/bg-2016-154 ◽

2016 ◽

Cited By ~ 1

Author(s):

Maximilian Weigand ◽

Andreas Kemna

Keyword(s):

Root System ◽

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Low Frequency ◽

Root Systems ◽

Nutrient Deprivation ◽

Impedance Tomography ◽

Non Invasive ◽

Polarization Response ◽

Crop Root

Abstract. A better understanding of root-soil interactions and associated processes is essential in achieving progress in crop breeding and management, prompting the need for high-resolution and non-destructive characterization methods. To date such methods are still lacking, or restricted by technical constraints, in particular for characterizing and monitoring root growth and function in the field. A promising technique in this respect is electrical impedance tomography (EIT), which utilizes low-frequency (< 1 kHz) electrical conduction and polarization properties in an imaging framework. It is well established that cells and cell clusters exhibit an electrical polarization response in alternating electric current fields due to electrical double layers which form at cell membranes. This double layer is directly related to the electrical surface properties of the membrane, which in turn are influenced by nutrient dynamics (fluxes and concentrations on both sides of the membranes). Therefore it can be assumed that the electrical polarization properties of roots are inherently related to nutrient uptake and translocation processes in the roots. We here propose broadband (mHz to hundreds of Hz) multi-frequency EIT as a non-invasive methodological approach for the monitoring and physiological, i.e. functional, characterization of crop root systems. The approach combines the spatial resolution capability of an imaging method with the diagnostic potential of electrical impedance spectroscopy. The capability of multi-frequency EIT to characterize and monitor crop root systems was investigated in a laboratory rhizotron experiment, in which the root system of oilseed plants was monitored in a water-filled rhizotron under ongoing nutrient deprivation. We found a low-frequency polarization response of the root system, which enabled the successful delineation of the spatial extension of the root system. The magnitude of the overall polarization response decreased along with the physiological decay of the root system due to the nutrient deprivation. Spectral polarization parameters, as derived from a pixel-based Debye decomposition analysis of the multi-frequency imaging results, reveal systematic changes in the spatial and spectral electrical response of the root system. In particular, quantified mean relaxation times (of the order of 10 ms) indicate changes in the length scales on which the polarization processes took place in the root system, as a response to prolonged nutrient deficiency. Our results demonstrate that broadband EIT is a capable non-invasive method to image root system extension as well as to monitor changes associated with root physiological processes. Given its applicability at both laboratory and field scales, our results suggest an enormous potential of the method for the structural and functional imaging of root system for various applications. This particularly holds for the field scale, where corresponding methods are highly desired but to date lacking.

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Reconstructing root system architectures from non-invasive imaging techniques for the use in functional structural root models

10.5194/egusphere-egu2020-693 ◽

2020 ◽

Author(s):

Magdalena Landl ◽

Katrin Huber ◽

Andreas Pohlmeier ◽

Jan Vanderborght ◽

Daniel Pflugfelder ◽

...

Keyword(s):

Root System ◽

Imaging Techniques ◽

Root Systems ◽

Root Water Uptake ◽

System Architectures ◽

X Ray ◽

Non Invasive ◽

System Reconstruction ◽

Mri Scans ◽

Good Agreement

The combination of functional-structural root-system models with root architectures derived from non-invasive imaging is a promising approach for gaining a better understanding of root-soil interaction processes. However, root architectures can often not be fully recovered using imaging, which subsequently affects the assessment of function via the functional-structural root models. In this study, we explored theoretical and actual possibilities of root system reconstruction from MRI and X-ray CT images. Experiments with water-filled capillaries showed the same minimum detectable diameter for both MRI and X-ray CT for the used parameter setup. Experiments with soil-grown lupine roots, however, showed significantly lower root system recovery fractions for MRI than for X-ray CT, from which most roots thicker than 0.2&#160;mm could be recovered. MRI allowed root signal detection below voxel resolution; however, the connection of this signal to a continuous root structure proved difficult for large, crowded root systems. Furthermore, soil moisture levels >30% hampered root system recovery from MRI scans in experiments with pure sand. To overcome the problem of low root system recovery fractions, we developed a new method that uses incomplete root systems as a scaffold onto which missing roots are simulated using information from WinRhizo measurements. Comparisons of root length within subsamples of semi-virtual root systems and root systems derived from X-ray CT scans showed good agreement. Evaluation of hydraulic root architecture measures of incomplete root system scaffolds and semi-virtual root systems proved the importance of using complete root system reconstructions to simulate root water uptake. Semi-virtual root reconstruction thus appears to be a promising technique to complete root systems for subsequent use in functional-structural root models.

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Изучение градиента биоэлектрического потенциала в корнеобитаемой среде

10.53040/gppb7.2021.09 ◽

2021 ◽

Author(s):

Т. Кулешова ◽

◽

Ю. Блохин ◽

Н. Галль ◽

Г. Панова ◽

...

Keyword(s):

Root System ◽

Root Zone ◽

Soil Layer ◽

Potential Gradient ◽

Potential Difference ◽

Bioelectric Potential ◽

Non Invasive ◽

Invasive Method

The work is devoted to the study of the bioelectric potential gradient in the root zone using a non-invasive method. It is shown that the dynamics of biocurrents generated in the rhizosphere is associated with the development of the root system. The potential difference at the level of 250 mV is also present in the soil without a plant, it decreases with time and the depth of the soil layer. The increase of the bioelectropotential by 150 mV and more is observed in the presence of the root system, apparently, when it grows to the electrode.

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X-ray microtomography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107058 ◽

1988 ◽

Vol 46 ◽

pp. 998-999

Author(s):

H.W. Deckman ◽

B.F. Flannery ◽

J.H. Dunsmuir ◽

K.D' Amico

Keyword(s):

Computed Tomography ◽

Internal Structure ◽

Imaging Technique ◽

Three Dimensional ◽

Tissue Structure ◽

Individual Element ◽

X Ray ◽

Non Invasive ◽

Panoramic Imaging ◽

Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

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