Numerous physiological processes in fruits depend on temperature, with consequences on fruit quality parameters like size, taste, appearance. Fruit temperature is also involved in plant injuries like sunburn and larval development. Fruit temperature is then a crucial parameter if one wants to investigate the impacts of climate change or to develop strategies to control fruit or larval developments. Fruit temperature results from a heat exchange between the fruit and the surrounding environment, the components of which - i.e., radiation, convection and evaporation - are strongly affected by plant architecture. In this paper, we develop a modelling approach to investigate relationships between tree architecture, microclimate and fruit temperature. First, plant architecture (tree digitizing), microclimate and fruit temperature (at fruit surface and within fruit) of selected fruits were measured during summer 2006 on three 14-year-old Golden Delicious apple trees trained in "Vertical axis", "Ycare" and "Drilling" systems. Fruit temperature exhibited a large variability at the tree scale. At the intra-fruit scale, temperature gradients of more than 10°C were measured. Data analysis revealed that radiation was the main microclimate parameter responsible for temperature distribution within tree crowns. Second, a modelling strategy based on the coupling of meteorological measurements, a method for estimating light partitioning at the intra-tree canopy scale, and a 3D physical model of temperature dynamics within fruits, was developed. Comparison between model results and experimental data showed usefulness but also limitations of such a model.
