EUROPEAN PEAR ARCHITECTURE AND FRUITING-BRANCH MANAGEMENT: OVERVIEW OF AN INRA RESEARCH PROGRAM

Abstract

Tree architecture traits are often described in relation to planting densities, tree height or adaptation of the tree to mechanical pruning. The need to reduce both pruning costs and the use of plant growth regulators (PGRs), notably in a context of integrated fruit production (IFP), lends further support to the development of architectural analysis as an aim in itself. A research program at the Institut National de la Recherche Agronomique (INRA), France, is currently focusing on two main objectives: the optimisation of training methods based on natural tree habit and the definition of new morphological criteria to better meet the needs of breeders. Resistance to pests and diseases, along with fruit quality, is also a major consideration. Observations are being carried out on trees of four cultivars in order to determine and compare their branching and fruiting patterns. Natural tree behavior is being investigated at two different development stages. The development of laterals along the trunk and their number and location during the earliest years of growth have been studied as the main determinants of tree architecture. A relationship is highlighted for differences in sylleptic branching between the first and second year shoots and the onset of bloom in the third spring. Observations were then carried out on fruiting branches once the adult stage had been reached. A relationship is shown between high-return bloom and the physiological abortion, called extinction, of a certain number of young spurs. On the other hand 'Angelys,' a newly released INRA cultivar, shows that a high alternation ratio at the individual spurs may be offset by an improved balance between vegetative and flowering spurs, resulting in more regular flowering over subsequent years (desynchronization phenomenon).