Biomechanics of plant anchorage at early development stage

We propose a minimal model for the response of seedlings to pullout constraints. Central to our approach is the idea of capturing not only average mechanical properties but also the stochastic component of the uprooting process. Our model accounts on one hand for the tensile elastic response of root fibres and on the other hand for the friction between root fibres and the soil matrix. We present for validation a dataset of 98 uprooting experiments using Avena sativa L. seedlings (common oat), growing in non-cohesive sediment under controlled conditions. We show that even if the architecture of the roots used in the experiments and, as a consequence, the components of our model are very basic, the uprooting curve (stress vs. strain) presents a complex response, with sudden jumps followed by partial elastic recovery. Depending on the maturity of the root system, we identify a crossover in the response of the seedling to the constraint. While for younger seedlings the anchorage rapidly fails after the peak force has been reached, more mature root systems recover from partial failures. Finally, we discuss the importance of the characteristics of the uprooting curve (maximal uprooting force and total uprooting work) regarding the ability of seedlings to withstand environmental constraints in terms of duration or intensity.