August 19, 2020
14 h
Louvain-la-Neuve
Sud 8
he general objective of this Ph.D. thesis is to quantify the direct and indirect impact of plant roots in soil electrical signature. Root affects the soil-plant system directly through its architecture but also indirectly via soil water depletion by uptake.
The first part of the thesis (Chapters 3 and 4) deals with understanding the direct impact of roots in small scale rhizotron and pot via process-based numerical models. We quantify the direct impact of roots while incorporating both direct (root explicit electrical properties) and indirect (root water uptake patterns) in the forward numerical model. To date this is the closest to reality, a numerical model can achieve in understanding electrical signatures of root systems in soils. We also prove that electrical response if measured in magnitude and phase components, magnitude part represents mainly indirect impact (root water uptake) while the phase part represents mainly direct impact (root architecture) and both magnitude and phase part contain root geometrical information.
The second part of the thesis deals with quantifying the indirect impact of water, i.e., soil water depletion in field-scale ERT experiments. We propose a new methodology where we use a numerical model to interpret field data. The model informed us if the changes we observe in the ERT experiment was due to plants or an artifact. This allowed us to quantify even the slightest changes in water depletion from different plants. Finally, we show that it is possible to phenotype similar plants belonging to different species at field scale using the ERT method.