Résumé
In the last decade, the consideration of fruit production as part of the entire tree development has become a new agronomic challenge, particularly with the emerging concept of the Integrated Fruit Production. This necessitates more consideration of the complexity of fruit tree biology with respect to perenniality and the year-on-year increase of tree structure. This has been made possible thanks to the development of methods used to describe and analyse entire tree structures. Over the same period, physiological processes have been investigated at a far more detailed level, thanks to progress made in cellular and molecular biology. These developments have prompted a new scientific question: how can knowledge acquired at the tree, organ, cellular or molecular levels be integrated? This paper attempts to highlight different points of view to address this new issue, with respect to fruit tree research. Integration is first considered in short time steps and for the physiological processes that allow plants to react to their environment. In this case, trees are considered as fixed structures. On an annual time scale, a few structural changes are taken into account e.g. for predicting organ development. Over a longer time scale, the specific tools used to describe, analyse and simulate year-on-year development of tree structure are reviewed. The integration of physiological functions and the year on year development opens up new perspectives for understanding fruit tree development but also raises new questions.