Modelling root-soil interactions using three-dimensional models of root growth, architecture and function

Background: Three–dimensional root architectural models emerged in the late 1980s provide an opportunity to conceptualise and investigate that all important part of plants that is typically hidden and difficult to measure and study. These models have progressed from representing pre–defined root architectural arrangements,to simulating root growth in response to heterogeneous soil environments, through incorporating soil properties and more complete descriptions of plant function. Modelling studiesare typicallydesigned to investigate the relationship between root architectural traits and root distribution in soil, and the spatio–temporal variability of nutrient supply. Root architectural models present an opportunity to investigate functional tradeoffs between foraging strategies (i.e. shallow vs deep rooting) for contrasting resources (immobile versus mobile resources), and their dependence on soil type, rainfall and other environmental conditions. The complexity of the interactions between root traits and environment emphasises the need for root architectural models in which traits and environmental conditions can be independently manipulated, unlike in the real world.

Scope: We provide an overview of the development of three–dimensional root architectural models from their origins, to their place today in the world of functional–structural plant modelling.The uses and capability of root architectural models to represent virtual plants and soil environment areaddressed. We compare features of four current models, SimRoot, ROOTMAP, SPACSYS and R-SWMS,and discuss the future development of root architectural models.

Conclusion: Root architectural models are being used to investigate numerous root–soil interactions, over a range of spatial scales. They are not only providing insights into the relationships between architecture, morphology and functional efficiency, but are also developing into tools that aid in the selection of root traits for improving plant performance in specific environments.