Regulation of water flow in the soil-root domain new tools and methods

Water flow in the soil-plant-atmosphere continuum is controlled by a handful of key features. On the plant side, the leaf stomatal conductance controls the total amount of water transpired while the root hydraulic properties defines the distribution of uptake sites in the soil domain. On the soil side, the soil hydraulic properties and the 3D distribution of water define the quantity of water available to the plant. The explicit integration of these factors is required to decrypt their quantitative influence in the uptake process at the plant scale. In this work, different tools were developed to facilitate the observation and analysis of water flows in the SPAC. Firstly, a new root image analysis software, SmartRoot, was created to enable a quantitative analysis of root system architecture. Secondly, the creation of an experimental platform made possible the parallel monitoring of soil water content and root architecture of 20 plants. Finally, the implementation of a new functional-structural plant model, PlaNet-Maize, allowed the simulation of water flow regulation at the plant level with a resolution down to the organ. Using these new tools, the quantitative influence of several root features on the water uptake processes was evaluated. Firstly, deep-rooted plants were shown to ensure a better distribution of the water content decrease in the soil profile. Secondly, the regulation of root axial and radial hydraulic properties were shown to ensure a fine regulation of the flow in response to changes in the soil environment. In conclusion, the successful development of new tools and methods allowed a more detailed analysis of the influence of several plant features in the water uptake process.(AGRO 3) -- UCL, 201