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

这个分项目的目的是开发光谱电阻抗断层成像技术，作为一种非破坏性工具，在实地对底土中的根系结构和功能进行成像、定性和监测。该方法利用了与根膜处的诱导电极化过程相关联的土壤-根界面的电容特性。这些产生特征性的电签名（阻抗谱），其在使用EIT的成像框架中是可测量的。在第一个项目阶段，该方法是通过在实验室中的受控根管实验。我们的目标是建立定量关系的测量阻抗谱的特性和参数描述根系形态，根的生长和活性依赖于根类型，土壤类型和结构（有/无生物孔隙），以及环境条件。并行这项工作，复杂的EIT反演算法，考虑到根系结构的自然特性时，解决固有的逆问题，将开发和测试的数值实验。因此，该项目将提供一个了解电阻抗谱的根结构和功能，以及专门适应EIT反演算法的成像和监测根动态。该方法将被应用在现场规模（中央现场试验在克莱因-阿尔滕多夫），其中非破坏性工具的成像和监测的底土根动态是非常需要的，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.