Soil plant interactions cover a multitude of different processes ranging from microscopic to landscape scales. Flux and potential are still hardly measurable in situ and therefore questions remain on the water flux controlling mechanisms in the soil-plant atmosphere continuum. Empirical models of stress have thus been developed for decades, but lack sometimes from sound mechanistic bases. We developed a plant scale modeling platform in which detailed information on root and soil structure and hydraulic properties are accounted for. In addition, solute transport in soil and in xylem vessels is also explicitly modeled, which allows us to simulate for instance nutrient uptake or chemical signaling, for instance.

Although computationally demanding, this model allows us to investigate the impact of small scale processes and their interactions on plant-soil relations. It can also be used to validate or develop simpler models. Four examples will demonstrate how this model may help explore open questions in soil-plant interactions:

1. Getting more insights on the impact of exudates on root water uptake and stress onset;

2. Understanding impact of salinity on stress ;

3. Investigating optimal root hydraulic traits for drought tolerance;

4. Developing novel simple stress models to account for the combination of chemical or hydraulic signaling to stomata in heterogeneous soils.

We will finally give discuss how to address current issues and future challenges.

This is a joint work with Valentin Couvreur, Xavier Draye, Katrin Huber, Felicien Meunier, Natalie Schroeder, Jan Vanderborght and Harry Vereecken.