Résumé
Manipulation of vegetative growth-fruiting relationships to ensure high quality fruits and regular cropping is the objective of all apple production systems. For several decades, the use of intensive orchards has been proposed to improve yield, notably early cropping, and profitability. The example of developments towards the Solaxe system in France shows that training concepts have evolved from a two-step vision to a more integrated vision of fruit tree management. In the former case, the aim is to establish a solid framework leading to non-bearing years and then, maintenance pruning is done to ensure cropping. In the latter case, tree structure is de-emphasized and greater importance is given to the control of fruiting as part of training procedures. Based on deeper knowledge of tree biology and genetic variation, the main objective is to orient overall tree vigor towards fruiting laterals for improving fruit quality and return bloom, rather than to influence vegetative vigor by means of dwarfing rootstocks or pruning. On the bearing tree, crop regulation is achieved by artificial extinction or, in short form, extinction, i.e. the complete and definitive removal of fruiting laterals (spurs and brindles), with chemical- and handthinning of remaining fruit buds if necessary. We recommend extinction more specifically in the center of the tree and on the underside of branches, first, to remove potentially poor-quality fruits and second, to improve light distribution within the tree. This training procedure favoring the peripheral layer of the tree canopy is known as centrifugal training (conduite centrifuge) and is now included in the LITE planting system. For 3 years, experiments have been carried out to assess the effects of these training concepts on fruit quality attributes and regular cropping. Results showed that centrifugal training increased fruit size and uniformity. Return bloom was also significantly enhanced with a tendency to increase lateral fruiting autonomy (bourse over bourse phenomenon)