Bolu yellow potato is a local potato variety cultivated in the soils of the Bolu Plain since the 1960s, valued both as a food crop and for seed use. This potato, produced alongside the Agria and Marfona varieties with the Latin species name Solanum tuberosum L., is grown within the geographical boundaries encompassing the central district of Bolu and the Dörtdivan district. This annual herbaceous plant, which can reach a height of 70–80 cm and produces white-pink flowers, is consumed solely for its tubers and propagates vegetatively. The tubers’ yellow flesh color, ability to cook without disintegrating, and distinctive flavor are its distinguishing characteristics.
The desired yield, flavor, and yellow coloration of Bolu yellow potato are achieved through suitable production methods combined with the region’s water, soil, and climate conditions. The area’s cool climate is favorable for potato development and enables the product to be stored for extended periods without chitting. Due to these properties, Bolu yellow potato is recognized nationwide for its suitability for winter storage and its bright yellow fry color. Its ability to cook without disintegrating, unique taste, and long-oval tuber shape make it preferred in traditional cuisine as well as in the production of frozen finger potatoes and chips.
Bolu yellow potato is a product registered as a geographical indication under Law No. 6769 on Industrial Property. The registration process was carried out by the Bolu Chamber of Commerce and Industry and officially took effect on 10 November 2020. This geographical indication, with registration number 589, is valid within the boundaries covering Bolu province and the Dörtdivan district. This region provides the natural and production conditions responsible for the product’s distinctive characteristics.
Botanical Characteristics
Aerial Organs: Stems emerging from tuber eyes number four to five and can grow up to 50–150 cm in height. Leaves consist of three to thirteen leaflets. Each stem terminates in a cluster of flowers. The fruit formed after flowering resembles a small tomato and may contain 150–200 seeds.
Subterranean Organs: The plant has a fibrous root system. Shoots emerging from the tuber grow horizontally to form stolons. The tips of these stolons swell and develop into tubers. After harvest, the tubers undergo a dormancy period of approximately two months.
Production Method
- Climate Requirements: Potato is a cool-climate crop. High temperatures reduce yield, but increased temperature during tuber development can enhance it. Temperatures below -1.5 °C slow emergence and reduce resistance to diseases. A rainfall of 200–300 mm is sufficient for normal yield.
- Soil Requirements: Loamy or sandy-loamy, well-drained, low-acidity soils are suitable. The ideal pH range is 5.4–7.5.
- Fertilization: It is recommended to apply 14–22 kg of nitrogen and 15–18 kg of phosphorus per hectare. Two-thirds of the nitrogen is applied before planting and the remainder before hilling and the first irrigation. All phosphorus is applied at planting.
- Crop Rotation: Continuous potato cultivation in the same field over consecutive years is not recommended. Rotational cropping with crops such as wheat or clover increases yield.
- Field Preparation: Deep plowing is performed in autumn and disk harrowing or tilling is carried out in spring to prepare for planting.
- Seed Tubers: Tubers weighing 50–80 grams are used. Large tubers may be cut before planting. Pre-sprouting should be conducted prior to planting, resulting in green shoots of 1–2 cm in length.
- Planting: Planting occurs when soil temperature reaches 8–10 °C. In irrigated agriculture, 200–250 kg of seed tubers per hectare are used; in dryland farming, 150 kg per hectare. Row spacing must be at least 60 cm. Planting depth varies between 2–5 cm. Planting methods include the ridge method, furrow method, plow furrow method, or mechanical planting.
- Cultural Operations: Weeding and hilling should be performed two to three times. Irrigation is carried out in three main stages: from emergence to tuber formation. The final irrigation before harvest should be followed by a one-week interval.
- Harvesting: Harvesting is done when leaves and stems have dried. It can be performed manually, with a plow, or using machinery. Early harvesting with a digger is possible but reduces yield and storage capacity.
- Storage: Storage can be done in bulk, in sacks, or in crates. Various methods are employed, ranging from earthen silos to modern storage facilities. When stored under appropriate temperature and humidity conditions, the product can be regularly supplied to the market throughout autumn, winter, and spring. The optimal storage temperature is 2–6 °C.InspectionInspections are conducted at least once annually under the coordination of the Bolu Chamber of Commerce and Industry. The inspecting authority monitors production methods, storage conditions, and the use of the geographical indication emblem. Non-compliance is reported to the relevant individual or institution. Additional inspections may be carried out when necessary. Expert support may be obtained from public and private organizations during the inspection process.
