A biophysical model of apple (Malus domestica Borkh.) fruit growth

Process-based fruit growth models are useful frameworks to advance our understanding of the development of fruit quality in response to climate and orchard management.
In this work, a model of apple (Malus domestica Borkh. ‘Jonagold’) fruit growth is presented, adapted from the model of Fishman and Génard of peach fruit, to account for a number of important features of pome fruit growth.
The model simulates fruit growth during the cell expansion phase, integrating growth processes as simple biophysical laws.
Water accumulation is calculated with the balance between xylem and phloem influx and transpiration water loss, with the water potential gradient as the driving force for transport.
Dry mass accumulation is modelled as the phloem sugar uptake and carbon depletion by respiration.
The main adaptations include 1) the decrease of the fruit surface conductance during development, 2) the declining xylem conductivity during growth, 3) diurnal variations of fruit volume with the inclusion of elasticity, 4) the decrease in cell wall extensibility during development.
The xylem water potential is estimated as a function of the air vapour pressure deficit.
In 4 growing seasons (2018-2021), experimental data were collected from apple orchards for parametrization, calibration and validation of the model.
The model simulations were in good agreement with the measurements and were able to simulate the overall fruit growth behaviour with respect to fruit fresh mass, dry mass and soluble solids mass.

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

B. Dequeker, J. Šalagovič, M. Retta, P. Verboven, B. Nicolaï

fruit growth model, water relations, transport, simulation, harvest prediction

https://doi.org/10.17660/ActaHortic.2022.1353.20