利用X射线CT技术研究根系三维构型的进展

Research advances on using X-ray CT in the study of 3-D root architecture

【目的】X射线CT扫描具有非破坏性、高分辨率等特点,近年来被广泛应用于研究植物根系三维构型。本文介绍了X射线CT技术研究植物根系的原理和方法,并重点阐述了CT图像提取和定量根系的方法。【主要进展】X射线CT可以穿透土体进而获取土体三维结构,并能通过图像分析准确定量土体内部的细节特征(如根系、孔隙等)。目前根系结构研究中应用的CT主要有医用CT、工业显微CT、同步辐射CT等,分别用于研究不同大小和分辨率要求的样品。应用CT扫描根系样品时,样品的制备和扫描参数的选择非常重要,样品的尺寸、容器的材质、扫描功率和扫描时长等因素都会影响CT图像质量。CT图像中提取根系的方法包括全局阈值法、区域生长法、根系追踪法、深度学习法等,结合图像预处理和后处理能更完整地提取根系。利用ImageJ、Rootrak、RooTh等软件,可以定量根系形态学参数(体积、根长、直径等),还可以分析根系三维分布特征(根系生长角度、根系生长深度等)。【展望】从CT图像中提取根系的算法在实际应用中仍存在很多问题,开发提取根系的先进算法,准确获取根系三维构型并将其定量表征,仍将是CT技术用于根系研究的重要方向。由于CT设备性能的特点,扫描样品尺寸和图像分辨率的矛盾仍然是关键问题,X射线CT硬件设备的创新和发展对其在根系研究中更加广泛和有效的应用具有重要意义。

【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 preprocessing 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.