A 3D hydromechanical model for cellular plant growth using the discrete elements method (DEM)

Several important quality parameters of fruit, such as firmness and texture, are determined by the microstructural properties of the fruit.
These microstructural properties are the result of cellular growth mechanisms, which can be studied through plant growth modeling.
At the tissue scale, modeling of plant growth and morphogenesis is inherently complex, as many cells interact mechanically as well as through water fluxes in multiple dimensions.
Therefore, growth models often use simplified 2D or 3D cellular geometries at constant turgor pressures to reduce complexity.
In previous work, we have developed a three-dimensional (3D) micromechanical discrete elements (DEM) model to simulate bruise damage in tomato at the cellular scale.
In this model, cells are represented as deformable spherical meshes, consisting of a network of nodes (discrete elements) connected through specialized springs, which represent the mechanical behaviour of the cell wall.
The model includes turgor pressure, intercellular adhesion and separation as well as cell rupture.
In this work, the DEM model is expanded to simulate growth and morphogenesis of fruit tissue after cell division.
To achieve this, cell wall growth was added to the model based on the Lockhart-Ortega equations.
Additionally, a method was developed to add apoplasmic water transport, that enables the connection between turgor pressure, cell wall tension and cell water uptake.
Such hydromechanical coupling has been implemented for simplified two-dimensional hexagonal cell geometries, but here, using DEM allows to generate realistic three-dimensional tissue structures in fruit.
The modeling approach was validated for a single spherical cell and effects of different hydromechanical parameters on growth rate were analysed.
In next steps, the model will be extended and applied in various test cases to study the development of different fruit tissue microstructures.
The generated microstructures will be validated against X-ray micro-computed tomography images of fruit tissue samples at several stages during growth.

XXXI International Horticultural Congress (IHC2022): International Symposium on Integrative Approaches to Product Quality in Fruits and Vegetables

H. Van Cauteren, J. Vangheel, P. Verboven, B. Smeets, B. Nicolaï

Lockhart-Ortega, single cell, turgor pressure, cell wall, wall growth, extensibility, water transport

https://doi.org/10.17660/ActaHortic.2022.1353.18