Ziyu Purple Yam from Zengcheng

Ziyu Purple Yam from Zengcheng

　　Ziyu Purple Yam is a mid-season variety with a growth cycle of 210 days. It is an annual or perennial twining vine plant. The plant can grow to a height of 400–500 cm, with lateral vines spreading 200–300 cm; the stem twines to the right, has a square cross-section, with the main stem approximately 0.4 cm in diameter and short purple ridges along its edges; the leaves are 10–16 cm long and 6–10 cm wide, with petioles about 12 cm in length. The leaves are broadly ovate, tapering to a point at the tip, with a broadly cordate base, and are greenish-blue in color. The leaf surface is smooth, with a reticulated vein pattern; there are seven primary veins, and both the base of the petiole and the areas where veins connect are purplish-red in color. Leaf arrangement is opposite in the middle, and alternate at the base and tip. Very few or no aerial tubers (yuzhu) grow in the leaf axils. The plant rarely flowers or does not flower at all; when it does, it produces small white flowers on a spike inflorescence at the tip of a three-angled capsule. The tuber is long and rod-shaped, straight and uniform, measuring about 80–100 cm in length, with individual tuber weight of 1.5–2.5 kg, and yield per mu (approximately 0.067 hectares) ranging from 1500–2500 kg. The skin is purple-red or brownish, and the crown (top part) is light red. The tuber has many fibrous roots, a smooth surface without cracks, strong storability, and good market appearance. The flesh is purple-red, dense, mildly sweet, crisp when eaten raw, and soft, powdery, and delicate when cooked, with a faint aroma. The plant has vigorous growth and many branches; it is adaptable, preferring warm temperatures and strong sunlight, with optimal growth temperatures of 20–30°C. It has strong heat and drought resistance, moderate resistance to waterlogging and cold. It can be processed into slices, powder, and other forms.