TY - THES A1 - Rudolph-Mohr, Nicole T1 - A novel non-invasive optical method for quantitative visualization of pH and oxygen dynamics in soils T1 - Entwicklung einer neuen, nicht invasiven, optischen Methode für die quantitative Darstellung von pH und Sauerstoffdynamiken in Böden N2 - In soils and sediments there is a strong coupling between local biogeochemical processes and the distribution of water, electron acceptors, acids and nutrients. Both sides are closely related and affect each other from small scale to larger scales. Soil structures such as aggregates, roots, layers or macropores enhance the patchiness of these distributions. At the same time it is difficult to access the spatial distribution and temporal dynamics of these parameter. Noninvasive imaging techniques with high spatial and temporal resolution overcome these limitations. And new non-invasive techniques are needed to study the dynamic interaction of plant roots with the surrounding soil, but also the complex physical and chemical processes in structured soils. In this study we developed an efficient non-destructive in-situ method to determine biogeochemical parameters relevant to plant roots growing in soil. This is a quantitative fluorescence imaging method suitable for visualizing the spatial and temporal pH changes around roots. We adapted the fluorescence imaging set-up and coupled it with neutron radiography to study simultaneously root growth, oxygen depletion by respiration activity and root water uptake. The combined set up was subsequently applied to a structured soil system to map the patchy structure of oxic and anoxic zones induced by a chemical oxygen consumption reaction for spatially varying water contents. Moreover, results from a similar fluorescence imaging technique for nitrate detection were complemented by a numerical modeling study where we used imaging data, aiming to simulate biodegradation under anaerobic, nitrate reducing conditions. N2 - In Böden und Sedimenten sind biogeochemische Prozesse und die Verteilung von Größen wie Wasser, Elektronenakzeptoren, Säuregehalte und Nährstoffe in enger Weise miteinander gekoppelt. Diese wechselseitige Beeinflussung ist skalenübergreifend und reicht von sehr kleinen bis zu größeren Skalen. Die in realen Böden vorhandene Struktur z. Bsp. Aggregate, Pflanzenwurzeln, Schichten und Makroporen bedingen eine starke räumlich Heterogenität und zeitliche Dynamik dieser Größen. Gleichzeitig sind Verteilung und Dynamik sehr schwer zu beobachten, zumindest ohne ihre gleichzeitige Störung. Bildgebende Verfahren bieten eine sehr gute räumliche und zeitliche Auflösung und ermöglichen die Darstellung dieser Größen. Um die dynamische Wechselwirkung zwischen Pflanzenwurzeln und Boden, aber auch die komplexen physikalisch – chemischen Prozesse in Böden zu verstehen, sind neue bildgebende Verfahren notwendig. Ziel dieser Arbeit war es, eine neue nicht-invasive Methode zu entwickeln, die es ermöglicht biogeochemische Parameter in der Wurzelzone zu visualisieren. Innerhalb dieser Studie wurde ein quantitatives bildgebendes Verfahren entwickelt, dass die räumlichen und zeitlichen Dynamiken des pH Wertes in der Rhizosphäre erfasst. Diese auf Fluoreszenzemissionen basierende Methode wurde ebenso für Sauerstoffdetektion entwickelt und mit Neutronen Radiographie kombiniert um gleichzeitig Aussagen über Wurzelwachstum, Sauerstoffzehrung durch Wurzelatmung und Wurzelwasseraufnahme treffen zu können. Die kombinierte bildgebende Methode wurde dann in einem künstlichen Boden genutzt um Nischen und Übergangsbereiche von Sauerstoff bei variierenden Wassergehalten zu charakterisieren. Das große Potential von bildgebenden Verfahren zeigt sich bei Modellierungsstudien. In dieser Studie wurden Bilddaten als Eingabeparameter für die Simulierung von denitrifizierendem biologischem Schadstoffabbau genutzt. KW - Optische Sensoren KW - pH KW - Sauerstoff KW - Fluoreszenzbildgebung KW - Rhizosphere KW - Optical sensor KW - pH KW - oxygen KW - fluorescence imaging KW - rhizosphere Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-66993 ER - TY - JOUR A1 - Rudolph-Mohr, Nicole A1 - Vontobel, Peter A1 - Oswald, Sascha T1 - A multi-imaging approach to study the root-soil interface JF - Annals of botany N2 - Background and Aims Dynamic processes occurring at the soil-root interface crucially influence soil physical, chemical and biological properties at a local scale around the roots, and are technically challenging to capture in situ. This study presents a novel multi-imaging approach combining fluorescence and neutron radiography that is able to simultaneously monitor root growth, water content distribution, root respiration and root exudation. Methods Germinated seeds of white lupins (Lupinus albus) were planted in boron-free glass rhizotrons. After 11 d, the rhizotrons were wetted from the bottom and time series of fluorescence and neutron images were taken during the subsequent day and night cycles for 13 d. The following day (i.e. 25 d after planting) the rhizotrons were again wetted from the bottom and the measurements were repeated. Fluorescence sensor foils were attached to the inner sides of the glass and measurements of oxygen and pH were made on the basis of fluorescence intensity. The experimental set-up allowed for simultaneous fluorescence imaging and neutron radiography. Key Results The interrelated patterns of root growth and distribution in the soil, root respiration, exudation and water uptake could all be studied non-destructively and at high temporal and spatial resolution. The older parts of the root system with greater root-length density were associated with fast decreases of water content and rapid changes in oxygen concentration. pH values around the roots located in areas with low soil water content were significantly lower than the rest of the root system. Conclusions The results suggest that the combined imaging set-up developed here, incorporating fluorescence intensity measurements, is able to map important biogeochemical parameters in the soil around living plants with a spatial resolution that is sufficiently high enough to relate the patterns observed to the root system. KW - Roots KW - soil-root interaction KW - root distribution KW - Lupinus albus KW - lupin KW - pH dynamics KW - oxygen dynamics KW - soil water distribution KW - rhizosphere KW - fluorescence imaging KW - neutron radiography Y1 - 2014 U6 - https://doi.org/10.1093/aob/mcu200 SN - 0305-7364 SN - 1095-8290 VL - 114 IS - 8 SP - 1779 EP - 1787 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Rudolph-Mohr, Nicole A1 - Gottfried, Sebastian A1 - Lamshöft, Marc A1 - Zühlke, Sebastian A1 - Oswald, Sascha A1 - Spiteller, Michael T1 - Non-invasive imaging techniques to study O-2 micro-patterns around pesticide treated lupine roots JF - Geoderma : an international journal of soil science N2 - The soil root interface is a highly heterogeneous system, e.g. in terms of O-2 and pH distribution. The destructive character of conventional methods disturbs the natural conditions of those biogeochemical gradients. Therefore, experiments aiming to control these influences and study pesticide kinetics under given O-2 and pH conditions suffer from a large uncertainty of the "real" O-2/pH at a certain position. Our approach with two different imaging techniques will examine the soil-root interface as well as the dissipation of the applied pesticide at a high spatial resolution. The obtained outcomes show directly that the pH has an influence on enantioselective dissipation of the acetanilide fungicide metalaxyl. In areas with high pH from an applied racemic mixture, the R-enantiomer dissipates faster than the S-enantiomer. Moreover, we found significantly reduced oxygen values in the bulk soil and vicinity of metalaxyl treated roots compared to control plant roots. The combination of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) and fluorescence imaging indicated the oxygen-dependent behavior of metalaxyl at the root surface. The results presented here underline the great potential of combining different imaging methods to examine the soil-root interfaces as well as the dissipation of organic pollutants in small soil compartments. (C) 2014 Elsevier B.V. All rights reserved. KW - MALDI imaging KW - Fluorescence imaging KW - pH KW - O-2 KW - Rhizosphere KW - Rac-metalaxyl Y1 - 2015 U6 - https://doi.org/10.1016/j.geoderma.2014.10.022 SN - 0016-7061 SN - 1872-6259 VL - 239 SP - 257 EP - 264 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Tötzke, Christian A1 - Kardjilov, Nikolay A1 - Hilger, André A1 - Rudolph-Mohr, Nicole A1 - Manke, Ingo A1 - Oswald, Sascha T1 - Three-dimensional in vivo analysis of water uptake and translocation in maize roots by fast neutron tomography JF - Scientific Reports N2 - Root water uptake is an essential process for terrestrial plants that strongly affects the spatiotemporal distribution of water in vegetated soil. Fast neutron tomography is a recently established non-invasive imaging technique capable to capture the 3D architecture of root systems in situ and even allows for tracking of three-dimensional water flow in soil and roots. We present an in vivo analysis of local water uptake and transport by roots of soil-grown maize plants—for the first time measured in a three-dimensional time-resolved manner. Using deuterated water as tracer in infiltration experiments, we visualized soil imbibition, local root uptake, and tracked the transport of deuterated water throughout the fibrous root system for a day and night situation. This revealed significant differences in water transport between different root types. The primary root was the preferred water transport path in the 13-days-old plants while seminal roots of comparable size and length contributed little to plant water supply. The results underline the unique potential of fast neutron tomography to provide time-resolved 3D in vivo information on the water uptake and transport dynamics of plant root systems, thus contributing to a better understanding of the complex interactions of plant, soil and water. KW - Environmental sciences KW - Optics and photonics KW - Plant sciences Y1 - 2021 U6 - https://doi.org/10.1038/s41598-021-90062-4 SN - 2045-2322 VL - 11 PB - Macmillan Publishers Limited CY - London ER - TY - GEN A1 - Tötzke, Christian A1 - Kardjilov, Nikolay A1 - Hilger, André A1 - Rudolph-Mohr, Nicole A1 - Manke, Ingo A1 - Oswald, Sascha T1 - Three-dimensional in vivo analysis of water uptake and translocation in maize roots by fast neutron tomography T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Root water uptake is an essential process for terrestrial plants that strongly affects the spatiotemporal distribution of water in vegetated soil. Fast neutron tomography is a recently established non-invasive imaging technique capable to capture the 3D architecture of root systems in situ and even allows for tracking of three-dimensional water flow in soil and roots. We present an in vivo analysis of local water uptake and transport by roots of soil-grown maize plants—for the first time measured in a three-dimensional time-resolved manner. Using deuterated water as tracer in infiltration experiments, we visualized soil imbibition, local root uptake, and tracked the transport of deuterated water throughout the fibrous root system for a day and night situation. This revealed significant differences in water transport between different root types. The primary root was the preferred water transport path in the 13-days-old plants while seminal roots of comparable size and length contributed little to plant water supply. The results underline the unique potential of fast neutron tomography to provide time-resolved 3D in vivo information on the water uptake and transport dynamics of plant root systems, thus contributing to a better understanding of the complex interactions of plant, soil and water. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1217 KW - Environmental sciences KW - Optics and photonics KW - Plant sciences Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-529915 SN - 1866-8372 ER - TY - JOUR A1 - Rudolph-Mohr, Nicole A1 - Toetzke, Christian A1 - Kardjilov, Nikolay A1 - Oswald, Sascha T1 - Mapping water, oxygen, and pH dynamics in the rhizosphere of young maize roots JF - Journal of plant nutrition and soil science = Zeitschrift für Pflanzenernährung und Bodenkunde N2 - Rhizosphere processes are highly dynamic in time and space and strongly depend on each other. Key factors influencing pH changes in the rhizosphere are root exudation, respiration, and nutrient supply, which are influenced by soil water content levels. In this study, we measured the real-time distribution of soil water, pH changes, and oxygen distribution in the rhizosphere of young maize plants using a recently developed imaging approach. Neutron radiography was used to capture the root system and soil water distribution, while fluorescence imaging was employed to map soil pH and soil oxygen changes. Germinated seeds of maize (Zea mays L.) were planted in glass rhizotrons equipped with pH and oxygen-sensitive sensor foils. After 20 d, the rhizotrons were wetted from the bottom and time-lapsed images via fluorescence and neutron imaging were taken during the subsequent day and night cycles for 5 d. We found higher water content and stronger acidification in the first 0.5 mm from the root surface compared to the bulk soil, which could be a consequence of root exudation. While lateral roots only slightly acidified their rhizosphere, crown roots induced stronger acidification of up to 1 pH unit. We observed changing oxygen patterns at different soil moisture conditions and increasing towards lateral as well as crown roots while extending laterally with ongoing water logging. Our work indicates that plants alter the rhizosphere pH and oxygen also depending on root type, which may indirectly arise also from differences in age and water content changes. The results presented here were possible only by combining different imaging techniques to examine profiles at the root-soil interface in a comprehensive way during wetting and drying. KW - crown roots KW - imaging KW - optical sensors KW - root exudation KW - root respiration Y1 - 2017 U6 - https://doi.org/10.1002/jpln.201600120 SN - 1436-8730 SN - 1522-2624 VL - 180 SP - 336 EP - 346 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Rudolph-Mohr, Nicole A1 - Bereswill, Sarah A1 - Tötzke, Christian A1 - Kardjilov, Nikolay A1 - Oswald, Sascha T1 - Neutron computed laminography yields 3D root system architecture and complements investigations of spatiotemporal rhizosphere patterns JF - Plant and soil N2 - Purpose Root growth, respiration, water uptake as well as root exudation induce biogeochemical patterns in the rhizosphere that can change dynamically over time. Our aim is to develop a method that provides complementary information on 3D root system architecture and biogeochemical gradients around the roots needed for the quantitative description of rhizosphere processes. Methods We captured for the first time the root system architecture of maize plants grown in rectangular rhizotrons in 3D using neutron computed laminography (NCL). Simultaneously, we measured pH and oxygen concentration using fluorescent optodes and the 2D soil water distribution by means of neutron radiography. We co-registered the 3D laminography data with the 2D oxygen and pH maps to analyze the sensor signal as a function of the distance between the roots and the optode. Results The 3D root system architecture was successfully segmented from the laminographic data. We found that exudation of roots in up to 2 mm distance to the pH optode induced patterns of local acidification or alkalization. Over time, oxygen gradients in the rhizosphere emerged for roots up to a distance of 7.5 mm. Conclusion Neutron computed laminography allows for a three-dimensional investigation of root systems grown in laterally extended rhizotrons as the ones designed for 2D optode imaging studies. The 3D information on root position within the rhizotrons derived by NCL explained measured 2D oxygen and pH distribution. The presented new combination of 3D and 2D imaging methods facilitates systematical investigations of a wide range of dynamic processes in the rhizosphere. KW - laminography KW - neutron imaging KW - rhizosphere biogeochemistry KW - 3D root KW - system architecture KW - root-soil interaction KW - root activity Y1 - 2021 U6 - https://doi.org/10.1007/s11104-021-05120-7 SN - 0032-079X SN - 1573-5036 VL - 469 IS - 1-2 SP - 489 EP - 501 PB - Springer CY - Dordrecht ER -