Does knowledge on fruit tree architecture and its implications for orchard management improve horticultural sustainability ? An overview of recent advances in the apple

UMR DAP équipe AFEF;UMR DAP équipe AFEF;Orchard planting systems are often associated with tree shape management which has direct and practical implications on training and pruning strategies. The objective of horticultural practices is to reach the required height and shape as fast as possible and maintain the tree framework in time and space. Scientific studies consider the individual crown shape and the spatial organization of trees within the orchard, which encompass tree height, planting distances, alley width and/or the leaf area index (LAI). Therefore, eco-physiological studies are mostly dedicated to the optimisation of orchard performances, highlighting the importance of light interception and distribution. At orchard level, the individual tree is often considered as a black box, and the turbid medium analogy hypothesized, i.e., tree crowns are filled with a uniform leaf area density and isolines of canopy light distribution are computed. An incremental improvement in the understanding of tree growth and fruiting strategies has been developed in the last three decades. Minimal pruning concepts have been proposed to fruit growers, limiting undesired vegetative reactions and taking advantage of the genetic variability of architecture. Applications of these concepts lead to early and more regular yield, and favour the homogeneity of fruit quality. Recent studies also showed that interactions exist between components of tree architecture, namely branching density and shoot growth dynamics, and development of orchard pests and diseases. Paralleling the better understanding of tree architecture, dramatic improvements of ecophysiological studies have been performed now including an explicit description of plant geometry. Using computer-generated three dimensional representations of digitised trees light interception and distribution can now be accurately modelled at tree and orchard scales. These approaches are therefore, capable of taking branch organisation into account and this can in turn open new hypotheses related to pest and disease occurrence. Emerging concepts in fruit tree manipulation, and their impacts on architecture and eco-physiology, undoubtedly open new avenues in orchard management with the objectives to meet horticultural sustainability, i.e., optimising labour efficiency and fertilizer and water use, and demanding less pesticid