Bolu Black Pumpkin

Bolu black pumpkin is an annual vegetable crop belonging to the species Cucurbita pepo L., cultivated in the vegetable fields and gardens of Bolu province. It was registered as a geographical indication on 11 October 2021 by the Bolu Chamber of Commerce and Industry under Law No. 6769 on Industrial Property, effective from 29 December 2020. Although its color ranges from yellow to orange and green, it is commonly known as “black pumpkin” among the local population and is also recognized as a green-skinned summer squash. Its distinguishing characteristics are determined by Bolu’s temperate and cold climate, duration of sunlight exposure, and the region’s unique loamy soil structure.

Morphological Characteristics

The plant can grow from 50 cm up to 4 meters in height. The stem is herbaceous, angular in cross-section, and initially green, gradually turning light green or brown over time. It bears spines and hairs. The leaves are oval, pentagonal, or heart-shaped; lobed, spiny, and toothed. The teeth may be pointed or blunt. Leaf surfaces are hairy with prominent veins.

Flowers develop in the leaf axils and are unisexual; male and female flowers occur on the same plant but at different locations. Male flowers have long stalks, while female flowers have short, thick stalks. The corolla petals are fused in structure and vary in color from pale yellow to dark yellow. The female flower stalk bears an ovary and a 3–5 lobed stigma.

The fruits have thick rinds and firm flesh. During normal harvest season, they measure 10–25 cm in length and 3–10 cm in diameter; when left to mature for seed production, they can reach 30–50 cm in length and 10–15 cm in diameter.

Cultivation and Production Method

• Field Establishment: Sowing or transplanting is carried out in April–May when soil temperature reaches 10–12 °C. Open-field cultivation is generally preferred. In pit planting, 2–6 seeds are sown per pit; after thinning, one or two seedlings are retained.

• Soil and Climate: Ideal soils are deep, well-drained, high in water retention capacity, and rich in organic and mineral matter. Temperate and cold climates are preferred; south-facing and low-elevation areas are recommended.

• Irrigation: Irrigation is avoided until the first fruits appear. Afterward, irrigation is recommended every 3–4 days.

• Hoeing: The first hoeing is performed when plants have 3–4 leaves. The second and third hoeings can be repeated at intervals of 2–3 weeks.

• Fertilization: It is recommended to apply 4–6 tons of composted farmyard manure per hectare. Nitrogen fertilizers should be used sparingly; phosphorus fertilizers should be applied at the time of planting.

• Pest and Disease Management: Use of healthy seeds, proper soil preparation, and biological or chemical control when necessary are recommended.

• Harvest: Harvesting is carried out when leaves turn yellow and dry, and the hairs on the fruit stalks fall off. Harvesting must be completed before frost and dew events, by the end of autumn.

• Storage: Due to its thick rind, the fruit can be stored in ordinary storage facilities. Cool, odorless, and dry environments are preferred; fruits should not be stacked on top of each other.

Geographical Boundary and Monitoring

Bolu black pumpkin is cultivated exclusively within the boundaries of Bolu province and is intrinsically associated with this region. All production, processing, and related activities must be conducted within this geographical boundary. Monitoring is carried out at least once annually under the coordination of the Bolu Chamber of Commerce and Industry; additional inspections may be conducted upon complaint. Inspections verify compliance with cultivation methods, harvesting practices, storage conditions, and proper use of the geographical indication.