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Effects of X-ray dose on rhizosphere studies using X-ray computed tomography

Zappala, Susan; Helliwell, Jonathan R.; Tracy, Saoirse; Mairhofer, Stefan; Sturrock, Craig; Pridmore, Tony; Bennett, Malcolm J.; Mooney, Sacha J.

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Susan Zappala

Jonathan R. Helliwell

Saoirse Tracy

Stefan Mairhofer

Professor of Computer Science

Sacha J. Mooney


X-ray Computed Tomography (CT) is a non-destructive imaging technique originally designed for diagnostic medicine, which was adopted for rhizosphere and soil science applications in the early 1980s. X-ray CT enables researchers to simultaneously visualise and quantify the heterogeneous soil matrix of mineral grains, organic matter, air-filled pores and water-filled pores. Additionally, X-ray CT allows visualisation of plant roots in situ without the need for traditional invasive methods such as root washing. However, one routinely unreported aspect of X-ray CT is the potential effect of X-ray dose on the soil-borne microorganisms and plants in rhizosphere investigations. Here we aimed to i) highlight the need for more consistent reporting of X-ray CT parameters for dose to sample, ii) to provide an overview of previously reported impacts of X-rays on soil microorganisms and plant roots and iii) present new data investigating the response of plant roots and microbial communities to X-ray exposure. Fewer than 5% of the 126 publications included in the literature review contained sufficient information to calculate dose and only 2.4% of the publications explicitly state an estimate of dose received by each sample. We conducted a study involving rice roots growing in soil, observing no significant difference between the numbers of root tips, root volume and total root length in scanned versus unscanned samples. In parallel, a soil microbe experiment scanning samples over a total of 24 weeks observed no significant difference between the scanned and unscanned microbial biomass values. We conclude from the literature review and our own experiments that X-ray CT does not impact plant growth or soil microbial populations when employing a low level of dose (


Zappala, S., Helliwell, J. R., Tracy, S., Mairhofer, S., Sturrock, C., Pridmore, T., …Mooney, S. J. (2013). Effects of X-ray dose on rhizosphere studies using X-ray computed tomography. PLoS ONE, 8(6), Article e67250.

Journal Article Type Article
Publication Date Jun 26, 2013
Deposit Date Apr 1, 2014
Publicly Available Date Apr 1, 2014
Journal PLoS ONE
Electronic ISSN 1932-6203
Publisher Public Library of Science
Peer Reviewed Peer Reviewed
Volume 8
Issue 6
Article Number e67250
Public URL
Publisher URL


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