Morphology of one and two year old dormant buds of apple trees in regions with insufficient chilling

Abstract

The aim of this study was to characterize the internal and the external morphology of dormant
buds of one and two year old twigs of apple trees cultivar Imperial Gala during Autumn and Winter in a region of insufficient chilling. Twigs carrying dormant buds were collected in seven distinct dates throughout the year of 2000 (April 19 th, May 10th, May 31 st, June 21st, July 12 th, August 2nd and August 23 th) and taken to the laboratory for
analysis. Part of the twigs was submitted to the biological test of single node cuttings in order to monitor the intensity of dormancy in each collection date. Despite the differences in dormancy intensity in each period, no internal or external morphological differences among buds were detected for the different collection dates. This indicates that, from April to August, no visible changes occurred. There were morphological differences between
one and two year old buds due to the formation of a cauline primordium in the interior of the two year old buds, perfectly connected to the stem tissue were the bud was inserted. Two year old buds have the potential to burst and to originate new shoots if favourable conditions are provided through plant management.