Bolu mountain hazelnut is a local hazelnut variety distinguished by its small kernel size, high protein content (24.3%), and high oil content (68.7%). In addition to direct consumption, it is used in the production of local hazelnut candy and chocolate. This product was applied for protection under the Industrial Property Law No. 6769 on August 10, 2017, registered as a “Designation of Origin” on December 18, 2020, and is protected within the borders of Bolu province. The registration was carried out by the Bolu Chamber of Commerce and Industry.
Approximately 991 kernels are found per kilogram; around 20 tons of product can be obtained annually from 250 mature trees. The fruit size ranges from 10 to 20 mm. Its thick shell and the dull portion at the base reaching up to half of the kernel are distinctive features. Bolu mountain hazelnut exhibits epigeal germination, flowers from late November to early December, and is harvested in the second half of August.
Tree Characteristics
The trees have a single trunk and produce few or no basal shoots. Leaf fall occurs early, mid, or late season. Crown shapes are upright, upright-spreading, or spreading. Trees can reach 15–35 meters in height and 1.30–1.60 meters in diameter. They withstand cold temperatures of -25°C to -30°C and can grow in clayey and alkaline soils.
The bark is dark gray, thick and cracked in older trees, resembling white oak bark. Young shoots are rusty-colored and hairy. Leaves are broad-ovate with serrated or lobed edges, turning golden yellow in autumn. Early flower clusters resemble a fox tail, and pollination begins from late winter to early spring. Trees are resistant to storms and snow cover, and pruning needs are minimal.
Production Method
Two main production methods are applied:
- Generative Production: Seeds are treated with a fungicide containing 80% Thiram, then subjected to cold stratification at +4°C for 3 months. After stratification, they are sown in tubes containing a mixture of 1/3 sand and 2/3 forest soil in a greenhouse.
- Vegetative Production: Grafting scions are taken from the upper parts of the tree. The whip-and-tongue English graft is preferred. The graft area is wrapped with heat bands set to 18°C, covered with peat, and moistened.
Bolu mountain hazelnut is cultivated in areas unsuitable for beech and fir trees, where competitive ability is low. Soil pH ranges between 5.4 and 7.9, generally slightly alkaline, and soils are non-saline. Cracked and vertically layered bedrock provides nutritional advantages. Soils vary from highly calcareous (58.4%) to calcareous-free.
Harvest begins in the second half of August and continues until the end of September. Hazelnuts are collected by hand or using shaking methods.
Control
Inspections are conducted under the coordination of the Bolu Chamber of Commerce and Industry by a three-member authority including representatives from the Bolu Provincial Directorate of Agriculture and Forestry and the Faculty of Agriculture and Natural Sciences at Bolu Abant İzzet Baysal University. Inspections are performed at least once a year and additionally if needed or upon complaint. Inspections verify planted areas, tree and kernel characteristics, and compliance with production methods. Public or private experts may be consulted if necessary.
