Bud structure in relation to shoot morphology and position on the vegetative annual shoots of Juglans regia L. (Juglandaceae)

The length and basal diameter of all lateral and terminal buds of vegetative annual shoots of 7-year-old #Juglans regia# trees were measured. All buds were dissected and numbers of cataphylls, embryonic leaves and leaf primordia were recorded. Each axillary bud was ranked according to the position of its associated leaf from the apex to the base of its parent shoot. Bud size and content were analysed in relation to bud position and were compared with the size and number of leaves of shoots in equivalent positions which extended during the following growing season. Length and basal diameter of axillary buds varied according to their position on the parent shoot. Terminal buds contained more embryonic leaves than any axillary bud. The number of leaves was smaller for apical and basal axillary buds than for buds in intermediate positions on the parent shoot only. All new extended shoots were entirely preformed in the buds that gave rise to them. Lateral shoots were formed in the median part of the parent shoot. These lateral shoots derived from buds which were larger than both apical and basal ones. (Résumé d'auteur