Evaluation of Climate Change Scenarios Effect on the Chilling Requirement for Deciduous Fruit Trees in Kiasar of Sari

Climate warming causes prevention of the latest spring frosts and reduces the spring freeze risk during flowering. The purpose of this study was to explore the effect of climate change on the chilling requirement and the flowering date of completion of the phonological stages of different plants in Sari. A 45-year weather data (1970-1970) of Kiasar Synoptic Station were used with data access from National Centers for Environmental Prediction. The predetermined output of the large-scale climatic model (CanESM2) was used after the downscaling observation for RCP2.6 scenarios. Using the ChillR and Climdex model, the flowering date of DOY (day of year) and the Growing Season Length (GSL) were estimated. Mann-Whitney non-parametric test and Kendall's trend were used to compare the first half of the near future (2016-2055) and the second half of the distant future (2056-2100) with the present. The results showed although the growing season length increases, but a significant difference between the air temperature in the chilling and forcing phases is caused a significant change in the appearance of phenology stages of the deciduous fruit trees in the studied area. Over the past decades (1980-2000), about two weeks was added to the length of the growing season. However, the flowering date will take place three decades earlier than the past climate. These significant changes in cultivated climate parameters lead to irreparable phonological disorders in the coming periods.