Comparison of different models for chilling requirements evaluation of sweet cherry cultivars in a Mediterranean area

Chilling requirements for breaking dormancy were investigated for two successive years in ten sweet cherry cultivars (‘Black Star*’,‘Burlat’,‘ Canada Giant® Sumgita*’,‘ Ferrovia’,‘ Giorgia’,‘ Lapins’,‘ New Star’, ‘Somerset’,‘ Sweet Early® Panaro 1*’ and ‘Sweetheart® Sumtare*’), chosen for their different blooming time. This study was carried out in Apulia (southeast Italy) under a mediterranean climate. Chilling requirements were calculated using four phenoclimatic models (hours below 7.2° C; Utah model; Utah Low Chilling model; Dynamic model) which were evaluated and compared. In our experimental conditions with a mild climate, the dynamic model performed better than the other methods here used. Indeed, following the dynamic model, chilling requirements observed were more homogeneous between the two years. The examined cultivars showed a wide range of chilling portions, from 58 (‘Burlat’, early flowering cultivar) to 84 (‘Ferrovia’, late flowering cultivar) .All the cultiars had their chilling requirements satisfied in climatic conditions of the experimental site.