A New Insight into Pruning Strategy in the Biennial Cycle of Fruiting: Vegetative Growth at Shoot and Whole-tree Level, Yield and Fruit Quality of Apple

Abstract

Knowledge of the growth dynamics of young and mature trees contribute to development of efficient orchard management practices. In this experiment, the aim was to provide apple growers with practical information on how vegetative growth (at both shoot and whole-tree level), yield and fruit quality change during the transition period, from young to mature trees. The experiment orchard was planted at 3.5 m × 1 m inter-row and intra-row spacings, respectively, with ‘Golden Delicious’/M.9 trees. Trees were trained since planting as modified vertical axis. Vegetative growth at shoot level reacted differently to yield load than that at the whole-tree level. The yield, yield efficiency and annual canopy volume increase and decrease (a vegetative growth indicator at the whole-tree level) showed a positive correlation with shoot length. TCSA (annual increase and actual TCSA), as another vegetative growth indicator at whole-tree level in the experiment, correlated negatively with shoot length. The yield varied biennially and, was greatest in the seventh year after planting (21.76±8.46 kg tree^-1, corresponding to an orchard yield of ~62 t ha^-1) that is an acceptable tonnage in the region of the experiment. To maintain the balance between vegetative growth and fruiting, orchard management practices should be conducted considering yield. No pruning or light pruning is recommended in the ‘off-year’ of biennial cycle of fruiting as a result of this study.