Developing X-ray Computed Tomography to non-invasively image 3-D root systems architecture in soil

• Published in: Plant and soil 2012-03, Vol.352 (1-2), p.1-22
• Main Authors: Mooney, S. J., Pridmore, T. P., Helliwell, J., Bennett, M. J.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Architecture; Biological and medical sciences; Biomedical and Life Sciences; Botanical research; Computed tomography; Computerized axial tomography; CT imaging; Ecology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Life Sciences; MARSCHNER REVIEW; Methods; Physiological aspects; Plant ecology; Plant growth; Plant Physiology; Plant roots; Plant Sciences; Plant-soil relationships; Plants; Rhizosphere; Root systems; Roots; Roots (Botany); Sandy loam soils; Soil fertility; Soil pollution; Soil samples; Soil science; Soil Science & Conservation; Soil water; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; Tomography
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-011-1039-9

Background The need to observe roots in their natural undisturbed state within soil, both spatially and temporally, is a challenge that continues to occupy researchers studying the rhizosphere. Scope This paper reviews how over the last 30 years the application of X-ray Computed Tomography (CT) has demonstrated considerable promise for root visualisation studies. We describe how early CT work demonstrated that roots could be visualised within soils, but was limited by resolution (ca. 1 mm). Subsequent work, utilising newer micro CT scanners, has been able to achieve higher resolutions (ca. 50 μm) and enhance imaging capability in terms of detecting finer root material. However the overlap in the attenuation density of root material and soil pore space has been a major impediment to the uptake of the technology. We then outline how sophisticated image processing techniques, frequently based on object tracking methods, have demonstrated great promise in overcoming these obstacles. This, along with the concurrent advances in scan and reconstruction times, image quality and resolution (ca. 0.5 μm) have opened up new opportunities for the application of X-ray CT in experimental studies of root and soil interactions. Conclusions We conclude that CT is well placed to contribute significantly to unravelling the complex interactions between roots and soil.