Response of different olive cultivars to late frosts in the Marche region (Italy)

In Europe, the intensity and frequency of late-winter frosts and spring frosts are increasing as a result of climate change. In olive (Olea europaea L.), frost damage can affect different tissues, from the leaves to the trunk, including inflorescences. A partial loss of inflorescences may not change the season’s fruit set, but if too many flowers are lost it would lead to a corresponding loss of production. On the Adriatic coast of central Italy, during the night of April 11, 2022, a few hours below zero were recorded. The low temperatures damaged the inflorescences of olives with different intensities based on cultivar and area. To evaluate the severity of the damages, the number of living and dead inflorescences were collected in several cultivars among several orchards. Data show that each cultivar showed a different behaviour in different orchards. ‘Arbequina’ showed 6% of dead inflorescences in the orchard of Maiolati Spontini, and 95% in the orchard of Agugliano. In Maiolati Spontini, only ‘FS-17’ showed a great loss of inflorescences. In the orchard of Fermo, ‘Rosciola’ showed higher damages. This different behaviour could be explained by small differences in temperature and humidity that are site specific, and to the exact phenological stage of the flowers in that particular moment. These observations could be helpful in determining the most adaptable cultivars to the future climate of central Italy. This objective is possible only by considering a mixture of cultivars, due to the different responses of the cultivars to the different and unpredictable types of frosts each year (winter, late winter, spring).