Introduction to the Characteristics and Cultivation Key Points of the Japanese Black Sweet Potato Variety

The Japanese black sweet potato is a rare sweet potato variety introduced into China from Japan in recent years. It is a dual-purpose variety grown for both stem tips and tuberous roots, and its nutritional content is 30%-50% higher than that of traditional Chinese varieties. It is called black sweet potato because of its purple-black skin and purplish-red flesh. This variety has many branches at the base, with vines about one meter long. The leaves are purple-green, relatively large and thick, heart-shaped, with deep purple veins and relatively long petioles. Tuber set is concentrated, and the tubers are spindle-shaped with long tips and uniform in size. The skin is purple-black, and the flesh is purplish-red. When cooked, it is tender, smooth, and refreshing, with a delicate fragrance and excellent taste. Generally, each plant sets 3-5 tubers, with a single tuber weighing 250-500 grams. During the seedling stage, growth vigor is relatively strong, tuber development starts early, and tuber shape forms relatively early. It has strong resistance to disease, disasters, and adverse conditions. It adapts to a wide range of regions and gives high and stable yields. After three years of trials and demonstrations by the Crop Improved Variety Research Institute of Shan County, Shandong, the average yield is 3,500-4,500 kg per mu for spring sweet potatoes and 2,500-3,500 kg for summer sweet potatoes. This variety has slender stems and vines. Only by pinching off 3-5 cm of the tender tips when the main vine and branches have extended 30 cm can the plant produce more branches and strong stems and vines, which helps promote early tuber formation and prevent excessive vine growth. In the middle and late stages, spray sweet potato swelling hormone or monopotassium phosphate to prolong leaf function, promote metabolism, and facilitate the formation and accumulation of dry matter in sweet potatoes.