The effect of environmental temperature on sweet cherry phenology

Summary Phenological data of sweet cherry ( Prunus avium L.) cultivars 'Burlat' and 'Germersdorfer' were analysed to ascertained the effect of air temperature on the onset of phenophases (first bloom, full bloom, end of flowering, maturity and calculated period of fruit development) during two 5-years-periods: before (P1) and during climate change (P2) in Slovenia. Although non-significantly higher mean temperatures from January to March during P1 influenced earlier date of flowering. The onset of 'Burlat' flowering phenophases were statistically similar during P1 and P2, being later first bloom and full bloom in P2, but the onset of 'Germersdorfer' flowering phenophases were significantly later during P2. Significantly higher mean temperatures of April and May during P2 shortened period of fruit development for 7 d in 'Burlat' and 11 d in 'Germersdorfer'. The speed of sweet cherry phenological progress was influenced by temperature of the preceding months. Shortened period of fruit development will most probably reduce sweet cherry fruit quality and yield, but advanced flowering after warmer winter months will increase risk of spring frosts.