Objectives X-ray CT scanning, with non-destructive, and high-resolution characteristics, has been widely used in the study of the three-dimensional root architecture in recent years. This article introduced the principles and methods of using X-ray CT technology to study plant root systems, with a focus on the extraction and quantitative analysis of root architecture from CT images.
Main advances X-ray CT can penetrate soil to obtain a three-dimensional soil structure, and accurately quantify internal features such as roots and pores. The CT instrument applied in root structure research include medical CT, industrial micro-CT, and synchrotron CT, depending on sample sizes and resolution requirements. The preparation of samples and the selection of scanning parameters are crucial for distinct CT scanning. Factors such as sample size, container material, scanning power, and scanning duration all affect the quality of CT images. Methods for extracting root architecture from CT images include global thresholding, region growing, root tracking, and deep learning. Combining image pre-processing and post-processing will help extracting roots more completely. Software such as ImageJ, Rootrak, and RooTh have been used to quantitatively analyze morphological parameters of root systems (volume, length, diameter, etc.), and analyze the three-dimensional characteristics of root systems (growth angle, root depth, etc.).
Outlook Developing advanced algorithms for entire root extraction and quantitative characterization of the three-dimensional root architecture remains a crucial direction for root architecture research by use of CT technology. Due to the characteristics of CT system performance, the contradiction between sample size and image resolution still is a key issue. The innovation and development of X-ray CT hardware are of great significance for its wider and more effective application in root architecture research.
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