Growth Context and Fate of Axillary Meristems of Young Peach Trees. Influence of Parent Shoot Growth Characteristics and of Emergence Date

Abstract

The relationship between several growth components of a shoot and the fates of the axillary meristems (developing in the axils of the leaves) borne by that shoot were studied, on first-order shoots of young peach trees. A comprehensive picture of those relationships was obtained by a discriminant analysis. Shoot growth at meristem emergence date was characterized by internode length, leaf-production rate and leaf-unfolding duration. All possible fates of axillary meristems at the end of the growing season (i.e. blind nodes, single vegetative or flower bud, bud associations, sylleptic or proleptic shoots) were considered. Shoot-elongation rate determined meristem fates quantitatively. The number of buds produced by a meristem increased when the shoot-elongation rate increased.Qualitatively, the fate of axillary meristems was related to the balance between shoot-growth components. If the subtending leaf unfolded slowly, sylleptic or proleptic shoots were more likely to develop than bud associations, for high shoot-elongation rates; and flower buds were more frequent than vegetative buds, for low shoot-elongation rates. Compared to flower buds, blind nodes appeared for similar shoot-elongation rates but longer internodes and lower leaf-production rates. The emergence date slightly modified the relation between shoot growth and axillary-meristem fates, but the main features held true throughout the growing season.The relationships between shoot growth and meristem fates may result from competitive interactions between the growing subtending leaf and the developing axillary meristem. Growing conditions might also influence both shoot growth and meristem fates by favouring either cell enlargement or cell division.