Rhizosphere functions in plant water uptake: Mechanistic link between carbon and water fluxes in the plant-soil system
Project Leader: Mohsen Zare, Maire Holz, Johanna Pausch
Team: Ruth Adamczewski
Duration: Feb 2022 - Jan 2025
Up to date, we have fragmented knowledge on the spatiotemporal carbon flux pattern into individual roots and their rhizosphere and also how such patterns may link to the functioning of roots regarding water uptake. The lack of information is mainly related to the technical difficulties of monitoring water fluxes and carbon fluxes at the scale of individual roots and their rhizosphere and also the dynamic nature of root water uptake and root exudation in soil-grown plants.
In this project, we aim to quantify water and carbon fluxes along the root system and then mechanistically link the pattern of carbon allocation into different root segments (i.e., root types and locations) and their rhizosphere to the functioning of roots in water acquisition from the soil. Our central hypothesis is that plants allocate more carbon to the production and maintenance of individual roots (type and regions) with greater functionality in water uptake.
This proposal comprises three main work packages (WP). In WP1, we plan to quantify root growth and water flux profiles along the root-shoot systems using a neutron radiography technique. These results will be combined with modeling of water flow and microscopic cross-sections of roots and shoots to estimate the profile of plant hydraulic conductivities. In WP2, we will mechanistically quantify carbon fluxes across the soil plant atmosphere continuum using a combination of 13C and 14C labeling experiments. In WP3 we will finally develop a process-based model of water and carbon flow across the soil plant atmosphere continuum, aiming to explore the link between carbon allocation into different root segments and their rhizosphere to the functioning of roots in water uptake. We will use two maize varieties (wildtype and root hairless mutant rth3) and grow them in two contrasting soil textures (loam and sand) under varying soil water contents (0.20 cm3 cm-3, 0.12, and 0.06 cm3 cm-3).
The combination of water and carbon fluxes across the soil plant atmosphere continuum will allow us to mechanistically link the pattern of carbon flux to the individual roots and their rhizosphere to the functioning of roots in water uptake. This information will provide a deeper understanding of feedbacks between carbon and water cycles across the soil plant atmosphere continuum