The root architecture is important for the acquisition of water and nutrients, their transport to aboveground organs and the mechanical stabilisation of the stem. Characterising root developmental processes is, therefore, crucial to the understanding of the plant fundamental functions, competition for resources, evolution and adaptation to the changing environment. Knowledge of root architecture is also important for designing effective and sustainable agronomic management practices.

Figure 1: Mini-rhizotron experiment used to track the dynamics of root apices.

Root architectures establish through elementary expansion and branching events at the proximity of apical meristems, the sites of active exploration. Initiated at the seed, the location of meristems is thought to propagate wave-like through the soil, leaving behind a permanent network of roots for the plant to acquire water and nutrients. We believe that contrasting 'meristematic wave' are a fundamental characteristic of plant species, allowing them to secure the different niche resources available in the soil.

We have developped a simple theoretical model incorporating root expansion, branching and gravitropic concepts, which can exhibit different types of waves patterns. Mini-rhizotron experiments are being used to monitor the evolution of the root density distribution in order to characterise the patterns of root meristematic waves in different species. Wave profiles will be used, for example, as a quantitative trait to explain mechanisms of underground competition, or will help to identify cultivars relying less on fertiliser inputs.

Figure 2: Architectural model showing the formation of a maximum of meristem density.

Simulation codes can be found on the archiroot web site.