Monitoring structural and physiological properties of crop roots using spectral electrical impedance tomography

Abstract

Non- or minimally invasive methods are urgently needed to characterize and monitor crop root systems, both on the laboratory and the field scale. Traditional research methods still overwhelmingly rely on manual labor, which slows down phenotyping and breeding programs.<br /> This thesis investigates electrical impedance tomography (EIT) as a non-invasive method for the characterization and monitoring of crop root systems. First, various improvements to the analysis methodology of electrical polarization measurements, required to investigate the small signal strengths encountered in biological tissue, are implemented and discussed. Second, multiple laboratory experiments with EIT on crop root systems are presented. Measurements were conducted in aqueous solutions, as well as in various substrate types. Root system extension could be successfully imaged with EIT in aqueous solutions, as were systematic electrical polarization responses in reaction to physiological stress situations. Substrates, however, still pose significant challenges for EIT measurements, due to their inherent polarizability and a strong influence of variable water content on polarization signals.<br /> In summary, EIT was successfully applied to characterize and monitor structural and physiological properties of crop roots in an laboratory environment. Although many challenges remain, establishing EIT as a reliable tool on the field scale is within reach.