Wheat root system architecture and soil moisture distribution in an aggregated soil using neutron computed tomography

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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Quantifying the effect of soil moisture content on segmenting root system architecture in X-ray computed tomography images

Plant and Soil ◽

10.1007/s11104-013-1596-1 ◽

2013 ◽

Vol 370 (1-2) ◽

pp. 35-45 ◽

Cited By ~ 31

Author(s):

Susan Zappala ◽

Stefan Mairhofer ◽

Saoirse Tracy ◽

Craig J. Sturrock ◽

Malcolm Bennett ◽

...

Keyword(s):

Computed Tomography ◽

Soil Moisture ◽

Moisture Content ◽

Root System ◽

System Architecture ◽

Soil Moisture Content ◽

Root System Architecture ◽

X Ray ◽

Computed Tomography Images ◽

X Ray Computed

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Visualisation and quantification of wheat root system architecture and soil moisture distribution in an aggregated soil using neutron computed tomography

10.5194/egusphere-egu2020-1196 ◽

2020 ◽

Author(s):

Tinashe Mawodza ◽

Manoj Menon ◽

Stuart Casson ◽

Genoveva Burca

Keyword(s):

Computed Tomography ◽

Organic Matter ◽

Soil Moisture ◽

Root System ◽

Soil Aggregates ◽

Neutron Imaging ◽

Moisture Distribution ◽

Plant Soil ◽

Soil Moisture Distribution ◽

Plant Soil Interactions

Sustainably intensifying global crop production in a world of diminishing natural resources is paramount for the attainment of zero hunger worldwide (a United Nations sustainable development goal). Key to this sustainable intensification is a deep understanding of the dynamics and complexities of plant-soil interactions for optimisation of plant productivity. Neutron computed radiography and tomography are powerful, non-invasive tools that enable the characterisation of plant-soil systems in situ. They also enable the visualisation and quantification of water distribution and movement within plant-soils systems. In this novel study, we use high resolution neutron computed tomography to investigate root system architectural differences in two different genotypes (Wild type vs TaEPF1-OE1-water use efficient mutant line) of bread wheat (Triticum aestivum). We further investigated how wheat roots interact with the heterogeneously distributed soil moisture. For this investigation, plants were grown in an aggregated sandy loamy soil with moderate amounts of organic matter (4%) for 13 days prior to imaging. We were able to produce a detailed three dimensional visualisation of the root architectural distribution of the two different genotypes imaged. These did not show significant differences between the two genotypes under investigation. We were also able to visualise relative soil moisture distribution and made inferences to how the roots of the wheat plants under investigation interact with the heterogeneously distributed soil moisture. Our results showed increased lateral root growth in regions with finer soil aggregates that had an estimated lower moisture content as compared to larger soil aggregates that retained higher amounts of moisture. This study demonstrates that detailed investigations into plant-soil interactions using neutron imaging techniques can be done successfully even in aggregated soils with considerable amounts of organic matter. This is a departure from the majority of neutron imaging experiments that predominantly use disaggregated sand soils devoid of organic matter as a growth medium.

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Quantifying the impact of soil compaction on root system architecture in tomato (Solanum lycopersicum) by X-ray micro-computed tomography

Annals of Botany ◽

10.1093/aob/mcs031 ◽

2012 ◽

Vol 110 (2) ◽

pp. 511-519 ◽

Cited By ~ 86

Author(s):

Saoirse R. Tracy ◽

Colin R. Black ◽

Jeremy A. Roberts ◽

Craig Sturrock ◽

Stefan Mairhofer ◽

...

Keyword(s):

Computed Tomography ◽

Root System ◽

Solanum Lycopersicum ◽

System Architecture ◽

Soil Compaction ◽

Root System Architecture ◽

Micro Computed Tomography ◽

X Ray ◽

The Impact

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Chickpea (Cicer arietinum L.) root system architecture adaptation to initial soil moisture improves seed development in dry-down conditions

10.1101/2020.09.24.311753 ◽

2020 ◽

Author(s):

Thibaut Bontpart ◽

Ingrid Robertson ◽

Valerio Giuffrida ◽

Cristobal Concha ◽

Livia C. T. Scorza ◽

...

Keyword(s):

Soil Moisture ◽

Root Growth ◽

Root System ◽

Seed Development ◽

Water Use ◽

System Architecture ◽

Adaptive Strategies ◽

Root System Architecture ◽

Initial Soil Moisture ◽

Initial Soil

AbstractSoil water deficit (WD) impacts vascular plant phenology, morpho-physiology, and reproduction. Chickpea, which is mainly grown in semi-arid areas, is a good model plant to dissect mechanisms involved in drought resistance.We used a rhizobox-based phenotyping system to simultaneously and non-destructively characterise root system architecture (RSA) dynamics and water use (WU) patterns. We compared the drought-adaptive strategies of ‘Teketay’ to the drought-sensitive genotype ICC 1882 in high and low initial soil moisture without subsequent irrigation.WD restricted vegetative and reproductive organ biomass for both genotypes. Teketay displayed greater adaptability for RSA dynamics and WU patterns and revealed different drought adaptive strategies depending on initial soil moisture: escape when high, postponement when low. These strategies were manifested in distinct RSA dynamics: in low initial soil moisture, its reduced root growth at the end of the vegetative phase was followed by increased root growth in deeper, wetter soil strata, which facilitated timely WU for seed development and produced better-developed seeds.We demonstrate that RSA adaptation to initial soil moisture is one mechanism by which plants can tolerate WD conditions and ensure reproduction by producing well-developed seeds. Our approach will help in identifying the genetic basis for large plasticity of RSA dynamics which enhances the resilience with which crops can optimally adapt to various drought scenarios.HighlightRoot system architecture and water use patterns change dynamically for distinct drought adaptation strategies in chickpea.

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