A biophysical model of apple (Malus domestica Borkh.) and pear (Pyrus communis L.) fruit growth

Fruit mass and sugar content are important quality attributes of apple and pear fruit. During fruit growth, water and sugars accumulate as a result of the coordination of water and solid fluxes. This causes expansive growth driven by turgor pressure and controlled by cell mechanical properties. To analyse the effect of environmental conditions on fruit growth dynamics, a biophysical model of apple (Malus domestica Borkh.) and pear (Pyrus communis L.) fruit growth was developed and adapted from the Fishman-Ge ' nard model. Dynamically changing patterns of average fruit fresh mass, dry mass and soluble solid mass in response to the environmental conditions during multiple seasons of varying environmental conditions were well captured by a parameterised model for apple and pear fruit growth. Sensitivity analyses showed that the model was most sensitive to variations in parameters related to active transport, cell wall extensibility and plant water status. The model enabled the analysis of how fruit growth dynamics were affected by stress conditions. This model, which integrates biophysical laws and parameters governing fruit water and solute dynamics, may serve as a basis to investigate the role of the processes involved in the complex growing behavior of pome fruit, and to optimise and predict fruit growth and quality.