Thorough knowledge of root system functioning is essential to understand the feedback loops between plants, soil, and climate. In situ characterization of root systems is challenging due to the inaccessibility of roots and the complexity of root zone processes. Electrical methods have been proposed to overcome these difficulties. Electrical conduction and polarization occur in and around roots, but the mechanisms are not yet fully understood. We review the potential and limitations of low‐frequency electrical techniques for root zone investigation, discuss the mechanisms behind electrical conduction and polarization in the soil–root continuum, and address knowledge gaps. A range of electrical methods for root investigation is available. Reported methods using current injection in the plant stem to assess the extension of the root system lack robustness. Multi‐electrode measurements are increasingly used to quantify root zone processes through soil moisture changes. They often neglect the influence of root biomass on the electrical signal, probably because it is yet to be well understood. Recent research highlights the potential of frequency‐dependent impedance measurements. These methods target both surface and volumetric properties by activating and quantifying polarization mechanisms occurring at the root segment and cell scale at specific frequencies. The spectroscopic approach opens up a range of applications. Nevertheless, understanding electrical signatures at the field scale requires significant understanding of small‐scale polarization and conduction mechanisms. Improved mechanistic soil–root electrical models, validated with small‐scale electrical measurements on root systems, are necessary to make further progress in ramping up the precision and accuracy of multi‐electrode tomographic techniques for root zone investigation.

中文翻译：

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感知根的电气特性：综述

全面了解根系功能对于了解植物，土壤和气候之间的反馈回路至关重要。由于根的不可接近性和根区过程的复杂性，根系统的原位表征具有挑战性。已经提出了电气方法来克服这些困难。导电和极化发生在根部及其周围，但机理尚未完全了解。我们回顾了用于根区研究的低频电技术的潜力和局限性，讨论了土壤-根连续体中电导和极化的背后机制，并解决了知识空白。可以使用多种电气方法进行根调查。使用植物茎中当前注射来评估根系扩展的报道方法缺乏稳健性。多电极测量越来越多地用于通过土壤水分变化量化根区过程。他们经常忽略根生物量对电信号的影响，这可能是因为它尚未被很好地理解。最近的研究强调了频率相关阻抗测量的潜力。这些方法通过激活和量化在特定频率下在根段和细胞尺度上发生的极化机制，既针对表面性质又针对体积性质。光谱方法开拓了一系列应用。尽管如此，要在现场范围内了解电信号，就需要对小规模的极化和传导机制有深入的了解。