Historical Change of Winter Chill Accumulation in Some Regions of Turkey

Deciduous fruit trees need to be exposed to low winter temperatures for a certain period time to produce regular crops. In addition to the effects of global warming in many other areas, its effect on cold accumulation is also a reason of concern. As a result, many studies have been carried out in important horticultural areas around the world on the impact of climate change on cold accumulation. In this study, historical changes of cold accumulation calculated using five models were examined in 12 locations in Turkey for the first time. Results show that there was no significant trend in cold accumulation in the provinces of Ankara, Bingöl, Diyarbakır, Malatya, and Tunceli. In some locations, the significance, magnitude, and direction of the chilling trend differed according to the model used. All five models used in the study indicated significant decreases in winter chill accumulation in Şanlıurfa, a site with relatively mild winters. In Erzincan, which has relatively cold winters, increasing trends were detected in cold accumulation calculated according to Utah, Modified Utah, and Positive Utah models. Results show that serious consequences may arise related to the chilling requirement of deciduous fruit trees, especially in regions with mild winters.