Heiyu Watermelon

Heiyu Watermelon

　　Heiyu Watermelon is renowned nationwide for its large size, thin rind, sweet and sandy red flesh, and being pollution-free. It is produced in Heiyu Village, Nanshi Town, Xuecheng District, and is sold to 11 cities including Shanghai, Nanjing, and Wenzhou. [] Species name

　　　　Watermelon; also known as: summer melon, cold melon, green gate jade chamber; Latin name: Citrullus lanatus; English name: watermelon

　　　　Taxonomy

　　　　Subclass of angiosperms, dicotyledon class, Cucurbitales order, Cucurbitaceae family, Citrullus genus

　　　　An annual sprawling herbaceous plant. The fruit has crisp, tender flesh that is sweet and juicy, rich in mineral salts and various vitamins, making it a primary cooling fruit in summer. Watermelon helps clear heat and relieve summer heat, and has auxiliary therapeutic effects on conditions such as nephritis, diabetes, and cystitis. The rind can be pickled, made into preserves, jams, or feed. The seeds contain up to 50% oil and can be pressed for oil, roasted, or used as cake ingredients.

　　　　Characteristics: Watermelon has a taproot system, with the main root extending over 1 meter deep. The root system is mainly distributed within the 20–30 cm soil layer. The roots are slender and easily broken, with weak regenerative ability and intolerance to transplanting. The young seedling stem is upright, elongating after 4–5 nodes, and then becomes prostrate after 5–6 leaves. It is highly branched, forming 3–4 levels of lateral branches. Leaves are alternate, with deep, shallow, or entire margins. Flowers are unisexual but on the same plant, with male flowers appearing on the 3rd–5th nodes of the main stem and female flowers on the 5th–7th nodes. A few bisexual flowers may appear during peak flowering. The corolla is yellow. The ovary is inferior, with parietal placentation. Both male and female flowers have nectar glands, are insect-pollinated, and open in the morning and close in the afternoon. Fruits come in shapes such as round, oval, ellipsoidal, and cylindrical. The surface may be smooth or ribbed, with rind colors including greenish-white, green, dark green, blackish-green, black, sometimes with fine netting or stripes. Flesh colors range from milky white, light yellow, deep yellow, light red, to bright red. Flesh texture is divided into firm and sandy. Seeds are flat, oval, or elongated oval, smooth or cracked. Seed coat colors include white, light brown, brown, black, or tan, either solid or mottled. Thousand-seed weight: large-seed type 100–150 g, medium-seed type 40–60 g, small-seed type 20–25 g. Small-fruit type 150–200 g.

　　　　Cultivation: Watermelon thrives in hot, dry climates. Optimal growth temperatures are 25–30°C, and it is susceptible to cold damage at 6–10°C. Open-field cultivation is only viable in regions where the monthly average temperature exceeds 19°C for more than three months per year. It is a long-day plant that prefers strong light, with a light saturation point of 80,000 lux. Suitable for hot, dry climates and highly drought-resistant, it requires well-drained, deep sandy loam soil with a pH of 5–7. China employs diverse watermelon cultivation methods. Open-field methods include dry pond cultivation and sandy field cultivation in the northwest, flat-bed cultivation in North China, and raised-bed cultivation in areas south of the Yangtze River. Protected cultivation includes windbreak cultivation in Beijing, reed mulch cultivation in Baoding, as well as plastic film mulching, plastic greenhouse cultivation, and greenhouse cultivation. Both open-field and protected cultivation begin with protected seedling raising in spring before transplanting. Base fertilizer is mainly organic, supplemented with superphosphate and potassium sulfate to increase fruit sugar content. Planting density is generally 500–600 plants per mu. North China practices pruning, with one vine and one fruit per plant; South China does not prune, resulting in multiple vines and fruits per plant. Growth period from sowing to harvest is about 80–120 days, and from female flower blooming to fruit ripening is about 30–50 days. Major diseases include Fusarium wilt, anthracnose, and powdery mildew; major pests include aphids, seed flies, and squash bugs.

　　　　Origin: Suitable for cultivation in most parts of the country. Large-scale cultivation occurs in Sishilipu, Yishui County, Shandong Province, and Laixi, Shandong Province. Nanlan Watermelon from Hetoudian Town, Laixi City, is famous for its sandy flesh, sweet taste, high moisture content, and rich nutrition.

　　　　Uses: Watermelon fruit is a major summer fruit. Mature fruits contain a high amount of water, with flesh sugar content typically ranging from 5–12%, including glucose, fructose, and sucrose. Sweetness increases in the later stages of ripening due to increased sucrose. It contains no starch, and sweetness may decrease post-harvest as disaccharides hydrolyze into monosaccharides. The seeds can be eaten as a snack, and the rind can be processed into watermelon jam. In traditional Chinese medicine, watermelon juice and rind are used to clear summer heat.

　　　　Known as the king of fruits, it was introduced from the Western Regions during the Han Dynasty, hence called watermelon. It is also an annual herbaceous plant of the Cucurbitaceae family, native to Africa. Currently, it is cultivated across most parts of China except for some remote cold regions, with a sweet taste and cooling properties.

　　　　Watermelon is a quintessential summer fruit and a major fruit of the season. On scorching summer days or sultry tropical nights, having chilled watermelon can effectively relieve heat.

　　　　Varieties: Based on differences, watermelons can be classified into three types: common watermelon, seed watermelon, and small watermelon