Longevity vegetable, also known as leaf sweet potato, is an annual herb belonging to the Convolvulaceae family. It originates from South American countries such as Brazil and Peru. During the Ming Dynasty (around 1580 AD), Chen Zhenlong introduced it to Guangdong and Fujian from the Philippines. Initially cultivated mainly for its tubers, this plant has gained popularity in recent years, especially in Hong Kong, Guangdong, and Guangxi, where the tender stems and young leaves are consumed. Renowned for its rich nutritional content, health benefits, and delicious flavor, it is often called the "Queen of Vegetables" in Hong Kong, commanding the highest price among leafy vegetables. In China's Changshou County, particularly in Bama County, Guangxi, it is commonly eaten as a staple vegetable, which is why it is referred to as a "longevity food."
Botanically, the plant features heart-shaped leaves, with round or hexagonal stems that can grow up to 10 meters long. It has strong branching ability between nodes, and petioles range from 15 to 25 cm in length. The leaves and stems come in green or purple varieties.
In terms of environmental requirements, the optimal growth temperature is between 23°C and 28°C, with a maximum limit of 35°C and a minimum of over 15°C at night (10°C–15°C). It thrives under strong light conditions, exhibits good drought resistance, but produces higher yields and better quality in moist environments. It prefers loose, fertile loam soil and requires balanced fertilization, with a nitrogen, phosphorus, and potassium absorption ratio of 1:0.4:1.
Not all sweet potato varieties are suitable for consumption. Some have a bitter taste and poor palatability. Ideal edible varieties should have tender young leaves, good flavor, vibrant color, no hair, strong axillary buds, vigorous growth, and high yield of stems and leaves. Varieties like Jingshu 4 and Lushu 7 are particularly well-suited for leaf use.
Propagation methods include cuttings and seedlings. Cuttings are the primary method. Healthy stems are cut into 15 cm sections with 3–4 nodes, and the base is shaped into a horseshoe shape. Soaking in fulvic acid for 10–20 minutes helps promote rooting and prevent bacterial infection. Cuttings are then planted in sandy loam beds, with a ground temperature of 16–23°C and air temperature of 20–28°C. Roots typically develop within about 30 days, after which the plants can be transplanted.
For site preparation, the planting area should be well-drained and equipped with irrigation facilities. Apply 3,000 kg of organic fertilizer per 667 m², deep plow the soil, and create raised beds 1.3 meters wide and 6–8 meters long. Plant two rows per bed with an average row spacing of 65 cm and 20 cm between plants. A total of 11,000 plants per 667 m² are recommended. Choose sunny locations and water immediately after planting.
Field management includes loosening the soil twice after cultivation, removing weeds, watering every 10 days after 15 days of seedling growth, and avoiding overwatering. Top-dressing with 200 kg of active chicken manure per 667 m² after seedlings, followed by 100 kg of active chicken manure or 15 kg of NPK compound fertilizer every 15 days during harvest. Spraying 0.2% potassium dihydrogen phosphate every 7–10 days for 3–5 times enhances growth.
Vines should be supported when the plant reaches 25 cm, using plastic ropes or bamboo scaffolds to keep them upright and maximize space utilization.
Harvesting begins when the plant reaches 40 cm in height, with regular picking of shoots and young leaves. It can be sold in bundles or boxes, with a harvesting period lasting over 6 months. Yield ranges from 3,000 to 4,000 kg per 667 m².
Nutritionally, 100 grams of edible portion contains 4.8 g protein, 0.7 g fat, 170 mg calcium, 47 mg phosphorus, 3.9 mg iron, 6.7 mg vitamin A, 503 mg potassium, 19.6 mg sodium, 61.6 mg magnesium, 0.4 mg copper, 0.3 mg zinc, 1.19 mg manganese, and 0.83 mg cesium—ranking first among 14 types of vegetables like cucumber, eggplant, tomato, and spinach.
Changshou Cai offers numerous health benefits, including immune regulation, improved disease resistance, anti-aging effects, increased platelets, hemostasis, cancer prevention, blood sugar reduction, laxative effects, diuresis, lactation promotion, detoxification, and treatment of night blindness.
Usage options include making salads by boiling the leaves first, then seasoning with garlic, salt, MSG, and sesame oil. It can also be stir-fried with seafood or mushrooms, used as a filling after boiling, or added to soups with glutinous rice or eggs, resulting in a smooth and fresh taste.
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