Enhancing agrometeorological services for frost risk assessment in fruit crops: from meteorological parameters to risk evaluation and adaptation

Damaging effects of sudden meteorological phenomena, such as spring frosts, pose a significant threat to fruit tree and shrub crops. Such events impact the flowers and fruit buds of the plants, causing substantial losses in yield in a given year. In some cases, the yield may be completely lost. A significant example of this phenomenon was the cold wave that occurred in April 2024 across substantial regions of Poland, Germany, and Czechia. It is also important to note that fruit orchards have a considerable economic importance; they underpin the livelihoods of numerous farmers and fruit constitutes a significant export commodity, for example in Poland. In order to ensure the optimal implementation of agrometeorological services, it is imperative to consider not only forecasts of the probability of frost based on meteorological parameters (i.e. the hazard) or, in climatological terms, relevant multiannual statistics. The risk approach should be consistently applied, incorporating the elements of hazard, exposure, and vulnerability. The latter is a particularly challenging task. In the context of damage to sensitive plant parts, the phenological approach is employed. It is imperative to consider the developmental stage of individual crop varieties at a given time and location in order to fully ascertain the risk related to frost. The methods currently available for tracking generative plant stages, such as flowering and fruiting, remain limited in comparison to those available for monitoring the rate of vegetative development. The latter can be more easily measured using satellite remote sensing. Consequently, the observation of phenological stages must be conducted directly. In this study, these observations serve as in-situ data for the validation of a model based on the concept of effective temperature sums: growing degree days. Consequently, the model results, corroborated by phenological observations in orchards across Poland, are employed to formulate concepts for novel operational products that demonstrate frost-related risk in a more comprehensive manner. The same base has the potential to be applied to evaluate climatologically future frost risk to fruit crops, after taking into account adequate climate change scenarios in the context of adaptation of the agricultural sector.