A 3D functional–structural plant model of shoot and root driven by soil hydraulics

Improved modelling of carbon assimilation and plant growth to low soil moisture requires evaluation of underlying mechanisms in the soil, roots, and shoots. The feedback between plants and their local environment throughout the whole spectrum soil-root-shoot-environment is crucial to accurately describe and evaluate the impact of environmental changes on plant development. Renato Braghiere and colleagues present a 3D functional structural plant model, in which shoot and root growth are driven by radiative transfer, photosynthesis, and soil hydrodynamics through different parameterisation schemes relating soil water deficit and carbon assimilation. The new coupled model is used to evaluate the impact of soil moisture availability on plant productivity for two different groups of flowering plants under different spatial configurations.

In order to address different aspects of plant development due to limited soil water availability, the authors constructed a 3D FSP model including root, shoot, and soil by linking three different well-stablished models of airborne plant, root architecture, and reactive transport in the soil. Different parameterisation schemes were used in order to integrate photosynthetic rate with root water uptake within the coupled model. The behaviour of the model was assessed on how the growth of two different types of plants, i.e., monocot and dicot, is impacted by soil water deficit under different competitive conditions: isolated (no competition), intra and interspecific competition.

“This new coupled model adds to the ongoing challenge of efficiently coupling models of multiple plant and soil compartments, and it presents an exclusive approach when in contrast with other models of the same kind,” say Braghiere and colleagues. “For example, much previous work on intercropping has used models that ignored the light environment, considering only soil resources, while other models specifically designed for intercropping may consider light environment and soil resources (e.g., water and nitrogen) but be designed to work on very different scales.”

“The potential of this new coupled model is related to its use as a tool for the development and testing of concepts, as well as the prediction of mechanisms and trends on single, monocropped, or intercropped plants. The model may be further extended to different phenotypes by estimating genotype performance based on measured root/shoot phenotypes.”