Non-destructive characterization and monitoring of root structure and function at the rhizotron and field scale using spectral electrical impedance tomography (ImpTom)

这一分项目旨在开发频谱电阻抗断层成像(EIT)，作为一种非破坏性工具，在田间范围内对地下土壤中的根系结构和功能进行成像、表征和监测。该方法利用了土壤-根部界面与根膜上的诱导电极化过程相关的电容特性。这些产生了特征电信号(阻抗谱)，这是可以在成像框架中使用EIT测量的。在第一个项目阶段，该方法是通过实验室中的根式加速器控制实验来开发的。其目的是建立测量的阻抗谱特征与描述根系形态、根生长和活性的参数之间的定量关系，这些参数依赖于根类型、土壤类型和结构(有/没有生物孔)以及环境条件。与这项工作并行的是，复杂的EIT反演算法将在求解固有逆问题时考虑到根系结构的自然特征，并将在数值实验中进行测试。因此，该项目将提供对根部结构和功能方面的阻抗谱的了解，以及特别适用的EIT反演算法，用于成像和监测根部动态。该方法将应用于田间尺度(克莱因-阿尔滕多夫的中央田间试验)，那里迫切需要非破坏性工具来成像和监测地下根系动态，但目前仍然缺乏。

This subproject aims at the development of spectral electrical impedance tomography (EIT) as a non-destructive tool for the imaging, characterization and monitoring of root structure and function in the subsoil at the field scale. The approach takes advantage of the capacitive properties of the soil-root interface associated with induced electrical polarization processes at the root membrane. These give rise to a characteristic electrical signature (impedance spectrum), which is measurable in an imaging framework using EIT. In the first project phase, the methodology is developed by means of controlled rhizotron experiments in the laboratory. The goal is to establish quantitative relationships between characteristics of the measured impedance spectra and parameters describing root system morphology, root growth and activity in dependence on root type, soil type and structure (with/without biopores), as well as ambient conditions. Parallel to this work, sophisticated EIT inversion algorithms, which take the natural characteristics of root system architecture into account when solving the inherent inverse problem, will be developed and tested in numerical experiments. Thus the project will provide an understanding of electrical impedance spectra in terms of root structure and function, as well as specifically adapted EIT inversion algorithms for the imaging and monitoring of root dynamics. The method will be applied at the field scale (central field trial in Klein-Altendorf), where non-destructive tools for the imaging and monitoring of subsoil root dynamics are strongly desired, but at present still lacking.