The high density peach planting system: present status and perspectives

The results achieved with high density planting (HDP) for apple orchards have led to a decisive thrust towards this approach in peach orchards. In order to evaluate the potential offered by application of HDP in this species, it is necessary to take into account both the means currently available for tree size control, which regulate canopy light interception and distribution, and also the training system most suitable to obtain high yield and good fruit quality. The main tools for tree size control are discussed: rootstocks, summer pruning, deficit irrigation, genetic modification of peach tree growth habit, root restriction, growth regulators. Furthermore, a survey conducted in the main peach-growing countries of the world, to investigate the extent of utilization and the main aspects characterizing peach and nectarine HDP orchards, is summarized. The most important training systems for HDP are then briefly described (free and sprint palmette, fusetto, delayed vasette, Tatura trellis and related training systems) jointly with their interaction with soil fertility. In medium or low fertile soil the fusetto presents uniform distribution of leaf area, early entry into production, good light penetration and good fruit quality; fusetto allows maximum planting density of 1200-1500 trees ha. In contrast, on extremely fertile soil it is necessary to adopt training systems that allow the canopy to develop as a single or double wall of limited thickness. The first alternative (palmette) allows maximum planting densities of 700-900 trees/ha. For orchards with planting densities greater than 1000-1500 trees/ha, the Tatura trellis and its variants (KAC V, perpendicular V) appear the most appropriate. Overall, the right choice of training system and orchard density will have to be made on the basis of careful economic analysis, taking into account the greater costs involved for the establishment and often also for the management of HDP