After initial invigoration by heading, young pear trees show reduction in axis vigour and increased propensity to flower.

Abstract

Fast establishment of the canopy in young trees, followed by reduced vegetative vigour and precocity are desirable traits in fruit production. Severe heading (cutting back the primary axis of the tree after the first year of growth) to induce branching is a nursery practice to increase early fruit yield. Our aim was to provide a systematic study of the responses of young pear trees to severe heading. We used an experimental system with two scion genotypes and three rootstocks to create trees with contrasting branching habits and vigour. The trees' trunks were headed and a single bud was allowed to outgrow in the following season. Architectural analysis was used to quantify the development of regenerated trees. In the first year after heading, the growth of the primary axes and, depending on the scion genotype, the sylleptic branching of regenerating trees, were invigorated. In the second year, the percentage of budbreak was also increased, but the shoot growth was greatly reduced. Axis propensity to flower in spring of the third year of growth was increased. The new insights into the effects of heading on tree aging and flowering will be used for guiding the best approaches to managing young pear trees.