Local climate change affects the apricot blooming in Tuscany, Italy

S. Bartolini, R. Viti
Climate models are forecasting for an increase of temperatures by the end of the 21st century around the world, especially for warm regions of the Mediterranean basin and southwestern regions. Thus, in a context of global warming, mild winter temperatures could greatly compromise the satisfaction of chilling requirement (CR) for the overcoming of flower bud endodormancy which depends on the perception of certain amount of cold temperatures. Consequently, the transition to ecodormancy, with the resumption of bud growth, represents a key factor impacting strongly on yields of temperate woody perennial species such as apricot (Prunus armeniaca L.). The aim of this research was to study, over a 25-year period, the influence of autumn-winter temperatures on date and intensity of apricot flowering in two apricot cultivars grown in central Italy (Tuscany) and characterized by early (‘San Castrese’) and late (‘Orange Red’) blooming time. The chilling requirement (CR) for breaking of flower bud endodormancy, estimated by chill units (CU) model, was also determined using the ‘forcing test’ able to define the capacity of buds to respond to warm temperatures after exposure to low temperatures. From the 1990s, a significant trend in warming of autumn-winter temperatures which determined a strong loss of CUs was observed. Nevertheless, the two examined cultivars were able to overcome the endodormancy of flower buds showing a certain plasticity to face changing environmental climatic conditions. However, serious consequences as concerns the blooming, in terms of intensity and date were found. Particularly for the early blooming cultivar, stronger repercussions were observed by a constant decrease of the flowering intensity which nowadays reached values of 50%. Moreover, a substantial blooming delay of about ten days was recorded. These results provide useful evidences for the future prediction of apricot fruiting success under climate change.
Bartolini, S. and Viti, R. (2020). Local climate change affects the apricot blooming in Tuscany, Italy. Acta Hortic. 1290, 19-26
DOI: 10.17660/ActaHortic.2020.1290.4
apricot cultivar, blooming date, blooming intensity, chill unit, temperature

Acta Horticulturae