Seasonal Carbohydrate Changes of the Bark Tissues of Hazelnut Cultivars Grown in the East and West Black Sea Region

The seasonal changes in total carbohydrate, fructose, glucose and sucrose levels of bark tissues of the Tombul, Palaz, Kalinkara, Cakildak and Sivri cultivars grown in the East and West Black Sea regions were determined by high performance liquid chromatography (HPLC). As with other fruit species, carbohydrate levels decreased from the end of spring to summer, showed steady changes with low values in summer and increased starting in the middle of fall until winter. Despite a general tendency of decline during spring, the carbohydrate and soluble sugar contents of Sivri increased in the Duzce region in April. Annual changes in carbohydrates from different regions and cultivars did not show significant differences. The differences between regions and cultivars were prominent in fall and winter. Sucrose levels were higher in December and January in Duzce, which has lower winter temperatures than Giresun. The opposite results were obtained for other sugar content levels except for the total carbohydrate and glucose content of Kalinkara in December and the total carbohydrate content of Palaz in January. Differences between regions during winter mostly occurred in the Palaz, Cakildak and Sivri cultivars. Sucrose levels were also higher in those cultivars in January. The Cakildak cultivar had more total carbohydrates in December and January than other cultivars in both regions.