• Moulia, Bruno
• Guena, Geoffroy
• Louf, Jean-François
• Badel, Eric
• Forterre, Yoël

Abstract

The perception of mechanical stimuli in the environment is crucial to the survival of all living orga-nisms, and plants make no exception. At the scale of a tree, the bending of a stem leads to a transient growth response, not only locally but also far away from the stimulated area, suggesting the existence of a long range in-formation signal within the plant network. The nature and mechanism of this long range signal is not well known, but it has been suggested that it could result from a purely hydraulic pressure signal created in response to the mechanical bending of the hydrated wood tissue. Recently, such hydro-mechanical coupling have been directly observed in plants in the PIAF-INRA Laboratory. The objective of this work is to better understand the physical mechanisms responsible for this hydro-mechanical response, by performing experiments on physical poroelastic beams mimicking stems and branches. To this end, we have designed an original three-dimensional micro- uidic device consisting of a transparent elastomer beam (PDMS) perforated with longitudinal micro-channels and lled with a viscous liquid. The poroelastic response of this biomimetic branch to a sudden bending has then been studied in a closed geometry. The main result of this study is that the bending of the articial branch generates a global overpressure in the system. This overpressure increases quadratically with the bending deformation, and is controlled by the pore bulk modulus of the media. We propose a simple model to explain our measurements and discuss the results in the context of plants.

Topics

• impedance spectroscopy
• pore
• experiment
• wood
• bulk modulus
• elastomer