Climate projections of frost risk for apple (Malus Domestica) in Slovenia

Due to climate change and increasing temperatures, the phenological development of fruit trees is expected to advance, which already results in higher susceptibility of fruit trees to crop-destroying spring frosts due to phenological stages of bud break or flowering occurring too early in the year. An assessment of the risk of tardive frosts for apple (Malus domestica) in Slovenia was made throughout the 21st century from temperature data of 6 climate model projections, specifically from regionally downscaled projections data of the EURO-CORDEX. The first part of the analysis was based on two phenological models - a classic GDD model and a two-phased BRIN model. In the second part of the analysis the conditional probability of frost occurrence was calculated from the statistical probability of the last day with frost conditions and the budburst event probability, as simulated by the chosen phenological models. The results showed that the probability of frost events occurring after flowering in Slovenian apple varieties increases throughout the 21^th century in the case of the RCP4.5, as well as the RCP8.5. We identified the period of 2071–2100 as the period when the majority of Slovenian apple-growing regions will be most prone to frosts, whereas during 2011–2040 and 2041–2070 the probability of frost occurrence might vary.

 

This work was supported by the Slovenian Research Agency, Research Program P4−0085.