Extreme Poisson's ratios recorded in the secondary phloem of Malvaceae: A highlight on the biomechanical function of bark

Alméras Tancrède, Corn Stephane, Baranger Anne, Regazzi Arnaud, Barés Jonathan, Lehnebach Romain, Clair Bruno. 2024. Extreme Poisson's ratios recorded in the secondary phloem of Malvaceae: A highlight on the biomechanical function of bark. Trees, 38 (6) : 1379-1390.

Url - jeu de données - Entrepôt autre : https://doi.org/https://doi.org/10.5281/zenodo.6673634

Résumé : In some angiosperm species, especially in the Malvaceae family, postural control and directional growth of the stem are enabled by the mechanical interaction between the growing cambium and the secondary phloem. A key feature of this motor mechanism is the ability to redirect the tangential stress induced in secondary phloem into a longitudinal stress enabling the control of stem orientation. Here we studied how the microstructure of the secondary phloem is optimized for this function. We measured the longitudinal-tangential Poisson's ratio and the longitudinal modulus of elasticity of secondary phloem in 22 tree species including Malvaceae and other families. We modeled the microstructure of Malvaceae secondary phloem using finite elements. The Poisson's ratio of secondary phloem from Malvaceae trees was found one to two orders of magnitude higher than for other species, reaching the highest values ever reported for a natural material. Mechanical modeling confirmed these results and showed that parameters of the microstructure of secondary phloem are set at value optimizing this Poisson's ratio. This highlights that the specific microstructure of Malvaceae secondary phloem is designed to maximize the conversion of cambial growth pressure into a longitudinal mechanical stress enabling the directional growth.

Mots-clés Agrovoc : phloème, Malvaceae, contrainte de cisaillement, Élasticité, écorce, écorçage mécanique, croissance, propriété mécanique, stress

Mots-clés géographiques Agrovoc : Guyane française, France

Mots-clés libres : Biomechanics, Gravitropism, Malvaceae, Poisson’s ratio, Posture control, Secondary phloem

Agences de financement hors UE : Agence Nationale de la Recherche

Projets sur financement : (FRA) CEnter of the study of Biodiversity in Amazonia, (FRA) Digital and Hardware Solutions and Modeling for the Environement and Life Sciences, (FRA) ANAEE-Services

Auteurs et affiliations

• Alméras Tancrède, Université de Montpellier (FRA) - auteur correspondant
• Corn Stephane, Université de Montpellier (FRA)
• Baranger Anne, INRAE (FRA)
• Regazzi Arnaud, Université de Montpellier (FRA)
• Barés Jonathan, Université de Montpellier (FRA)
• Lehnebach Romain, CIRAD-ES-UMR Ecofog (GUF) ORCID: 0000-0001-6175-4437
• Clair Bruno, CNRS (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/613042/)

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