What are the key cultivation techniques for Wen Yujin (Curcuma wenyujin)?

Wen YujinAlso known as Wen Ezhu, commonly called Jianghuang (turmeric), it is a perennial herbaceous plant with persistent roots, belonging to the Zingiberaceae family. Yujin is the fleshy tuberous root; the underground portion at the base of the stems and leaves is Ezhu. The tuberous root is used medicinally to promote the flow of qi and relieve depression, cool the blood and break blood stasis, promote bile secretion and relieve jaundice, and relieve pain; the rhizome is used to treat blood stasis amenorrhea, abdominal pain, and traumatic injuries. It is mainly distributed in Wenzhou, Zhejiang, southern Zhejiang and other areas, and is also cultivated elsewhere.

Since Wen Yujin is a medicinal plant in which two parts of a single plant are used medicinally, to make both Yujin and Ezhu grow well, achieve high yields and good medicinal quality, the following cultivation and management points must be emphasized:

I. Growth habits

Wen Yujin prefers warmth, tolerates drought, dislikes waterlogging and fears frost. Its entire growth period is about 240 days. It is generally planted in the first lunar month and can be harvested in mid-October of the same lunar year. When the temperature stabilizes above 13°C, the tuberous root seedlings of Wen Yujin can germinate and break through the soil, growing into young seedlings. Timely planting can increase the yield and medicinal quality of Yujin and Ezhu; planting too late shortens the growth period and reduces yield and quality.

II. Planting

Selecting rhizomes: Rhizomes are divided into six types: old heads, large heads, second heads, third heads, nipple heads and small nipple heads. In production, robust second heads and third heads with plump buds, no pests or diseases, and short, thick shapes are commonly used as seed material. The shorter and thicker the seed rhizome, the better.

Planting: Planting around Qingming is appropriate. For narrow beds, the plant spacing is 33 cm, single row. For wide beds, the plant spacing is 50 cm, with two rows planted in triangular holes. The holes are 18-20 cm in diameter and 6-10 cm deep, with flat bottoms; avoid excessively deep holes with pointed bottoms. If too deep, the tuberous roots scatter and harvesting is labor-intensive and difficult to complete. Plant one rhizome diagonally in each hole, with the bud facing upward, cover with burnt mud ash, then cover with 4-7 cm of soil, and then spread barnyard manure. Use 1500-2000 kg per mu, topped with 2000 kg of burnt mud ash.

III. Rational fertilization

Ezhu is the underground portion at the base of the plant's stems and leaves. Throughout its growth, it needs a certain amount of water and nutrients to promote its own growth and development, and it also grows fibrous roots to absorb water and nutrients from the soil and transport them to the plant leaves, where light energy is used to produce carbohydrates; these are transported by the stems to the plant's own nutritional roots that produce Yujin, and from the nutritional roots to the Yujin. Therefore, in cultivation and management, sufficient basal fertilizer based on decomposed organic fertilizer must be applied. In the early stage, quick-acting nitrogen fertilizer is applied as a top dressing to promote seedlings; in the middle stage, phosphorus and potassium fertilizers are mainly used to promote the growth and development of Ezhu and Yujin; in the late stage (the end of the 6th lunar month), since the tuberous roots of Yujin have already initially formed and the nutritional roots are relatively shallow from the surface soil of the plow layer, chemical fertilizers should no longer be applied as top dressing. This is because under conditions without water to dissolve them, chemical fertilizers at too high a concentration will damage the fibrous roots of Ezhu, causing seedling blight and rotting of the young Yujin on the nutritional roots.

IV. Draining waterlogging and preventing root rot

Wen Yujin is a dryland medicinal plant that likes moisture but fears waterlogging. The fibrous roots on Ezhu and the nutritional roots of Yujin are well developed and carry out respiration during growth. If the soil is waterlogged for a long time, oxygen in the soil gaps is insufficient, and the root system of Wen Yujin undergoes anaerobic respiration under oxygen-deficient conditions, producing large amounts of alcohol inside the roots, which leads to root rot and death. Therefore, draining waterlogging is an important measure to prevent root rot.

V. Timely harvesting

The best harvest period for Wen Yujin is about 1 week before Lidong (Start of Winter). At this time, Yujin and Ezhu are fully mature, with low water content and high medicinal content. Harvesting too early affects yield and quality; harvesting too late and encountering frost will cause frost damage to Yujin and Ezhu, affecting yield and quality.