Seasonal progression of bud dormancy in apricot (Prunus armeniaca L.) in a Mediterranean climate: A single-node cutting approach

The progression of the dormancy of apricot (Prunus armeniaca L.) vegetative and reproductive buds in the summer-winter period (June-March) was analysed with the single-node cutting method during two consecutive years in a Mediterranean climate. The progression of the mean time to budbreak (MTB) was studied. Low MTB values were obtained, which show endodormancy intensity under climatic conditions in the South East of Spain only reached a shallow level in apricot. The onset of bud dormancy occurred prior to the advent of chilling accumulation. Although an oscillating pattern on dormancy progression was observed, MTB increased progressively from summer until January and declined rapidly thereafter coinciding with dormancy breaking, although in 2006-2007, maximum endodormancy intensity was observed at beginning of October. Vegetative and reproductive buds showed a similar pattern of seasonal progression of MTB, although after flower differentiation (ca. September) vegetative buds always showed a deeper dormancy than reproductive buds. Autumn and early winter temperatures seem to play a crucial role over dormancy intensity and dormancy progression. A gradient of increasingly deep dormancy from shoot apex to base is suggested by the gradual increment of MTB in a basipetal direction, although it was influenced by the year.