Chronologie du développement du fruit en relation avec la croissance végétative chez l'abricotier Prunus armeniaca L. cv. Rouge du Roussillon

The chronology of fruit development and vegetative growth is described for the apricot cultivar 'Rouge de Roussillon'. We observed a synchrony between the major events of fruit development and those of vegetative growth. This allows us to complete a descriptioon of phases in fruit by taking in account the unfurling of preformed, then newly formed parts of growth units (GU). During the first period, which lasts approximately 12 days following full flowering, numerous events unfold simultaneously. In the absence of leaves, everything the tree produces during this period depends on its reserves. During the second period (from around 12 to 30 days) cell division ceases in the future fruit and the preformed parts of the growth units unfurl. From 30 to 60 days after full flowering, the fruit develops little, while the neoformed parts of the growth units are formed. The cessation of growth is spread out at intervals during this period and, at 60 days, 80% of GU have ceased to grow. The embryo continues its development until about 90 days, while the number of growing shoots is limited. Finally, beyond 90 days, the fruit finishes its enlargement while new growth units appear on the tree. The period of direct concurrence between vegetative and floral development seems limited to the two early periods. In effect, the preformed leaves in the winter bud seem to be incapable of providing assimilates to all the growing organs. Consequently, the priority is alternatively vegetative growth (unfurling of newly formed leaves) then fruit development.