Understanding How Plant Roots Negotiate Obstacles

Plant roots exhibit a remarkable capability for navigating in the underground environment, digging through soil and overcoming obstacles, while also efficiently searching for nutrients and water. They dig by growing (adding material at the tip) thus exerting forces on the environment, and their growth rate is in turn affected by the stiffness of the environment. Observations of roots coming into contact with obstacles suggest a complex combination of passive mechanical responses and active growth-driven responses. Here we tackle this problem by developing a model that relates the growth rate of a plant root to the mechanical properties of both the root and the obstacle, which provides quantitative insight into the observed first contact dynamics. Furthermore, we develop a robust numerical framework which takes into account this relation, allowing to simulate complex scenarios in 3D, including obstacles of varied geometries and mechanical properties. This framework allows to answer questions which are otherwise analytically inaccessible.