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  - Toetzke, Christian
A1  - Kardjilov, Nikolay
A1  - Manke, Ingo
A1  - Oswald, Sascha
T1  - Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography
JF  - Scientific reports
N2  - Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-06046-w
SN  - 2045-2322
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  -