How to Grow Coptis chinensis for High Quality? Detailed Key Points of Cultivation Techniques

I. Growth Habits

Coptis chinensis prefers cold, high-altitude cool environments, likes shade and moisture, and dislikes direct strong light, high temperatures and dryness. In the wild it is mostly found in high mountain areas at altitudes of 1200—1800 m; for cultivation, areas at altitudes of 1400—1700 m should be chosen. The temperature range for normal plant growth is 8—34 degC; below 8 degC or below 5 degC the plant enters a dormant state. The seeds have post-embryonic dormancy characteristics; after storage in wet sand at 3—5 degC for 5—6 months, dormancy can be broken and the germination rate can reach about 90%. Seed longevity is greatly affected by storage conditions; both dry storage and wet sand storage at room temperature find it difficult to maintain seed viability for long. Generally, under conditions of minus 2—0 degC and a certain humidity, the seeds can retain their vitality for many years.

II. Cultivation Techniques

1. Site Selection and Land Preparation

Coptis chinensis has strict soil requirements; loam and sandy loam with deep, fertile, loose, well-drained topsoil rich in humus are best. A soil pH of 5.5—7 is suitable. Continuous cropping should be avoided. Gentle slopes with half shade and half sun, receiving oblique sunlight in the morning and evening, are most suitable, but the slope should not exceed 30 degC. Traditionally, sheds are mostly used for growing Coptis chinensis. Nowadays, interforest cultivation or intercropping with other crops is often used. For interforest cultivation, low-growing evergreen or deciduous broad-leaved mixed forests, or evergreen coniferous and broad-leaved mixed forests with good canopy density should be chosen; tall trees should not be used. Before land preparation, soil fumigation is carried out as follows: on a sunny day, turn up the humus soil 7—10 cm from the surface, pick out tree roots and stones, and after the humus soil dries, collect dead branches, fallen leaves and weeds for soil fumigation. This method helps increase soil fertility and reduce pests, diseases and weeds. After fumigation, plow 15 cm deep, pick out tree roots and other debris, apply about 4000 kg of farmyard manure per mu as base fertilizer, rake evenly and level, and make beds 1.5 m wide and 30 cm high, with furrow width of 50 cm. The bed surface should be slightly arched.

2. Planting Methods

(1) Sowing: Seeds just harvested can be sown in summer; stored seeds are best sown in October—November. The sowing rate per mu is 2.5—3 kg. Before sowing, mix the seeds thoroughly with 20—30 times their volume of fine humus soil, broadcast evenly over the bed surface according to the rate, press lightly after sowing, and cover with fine soil. In dry winter areas, cover with a layer of straw after sowing to keep the soil moist. After thawing the following spring, remove the covering grass to facilitate seedling emergence. Summer sowing is rarely used.

(2) Transplanting: Seedlings can be transplanted in 3 periods: February—March, June, or September—October, with June transplanting being best. However, in low-altitude areas, transplanting should be done directly in February—March or September—October. Transplanting is best done on cloudy days or sunny days after rain; take robust seedlings with more than 4 true leaves, dig them up with roots, trim some fibrous roots leaving 2—3 cm, and plant squarely at a spacing of 10 cm between plants and rows. The depth depends on the transplanting season and seedling size; plant shallower in spring or for small seedlings, and slightly deeper in autumn or for large seedlings, generally 3—5 cm, leaving 3—4 large leaves above ground. Usually, seedlings are dug in the morning and planted in the afternoon; if the dug seedlings are not all planted that day, spread them in a cool, moist place. Before transplanting the next day, soak the roots in 0.05—0.1 ml/L (ppm) ABT rooting powder for 10 minutes, which can significantly increase the transplanting survival rate of Coptis chinensis seedlings and promote their growth and development.

3. Field Management

(1) Seedling Stage Management: After sowing, seedlings emerge the following spring in March—April; remove the covering before emergence. When seedlings have 1—2 true leaves, thin them to a plant spacing of about 1 cm; in June—July, spread a layer of fine humus soil about 1 cm thick over the bed surface to stabilize the seedling roots. The shade shed should be set up before emergence, 1 shed per bed, 50—70 cm high, with canopy density controlled at about 80%. If raising seedlings in the forest, the canopy density must be adjusted before sowing.

(2) Replanting: After transplanting Coptis chinensis seedlings, dead seedlings often occur. Generally, seedlings planted in June are replanted in autumn, and those planted in autumn are replanted after thawing the following spring.

(3) Cultivation and Weeding: The seedling bed has many weeds; weed at least 3—5 times per year, and 2—3 times per year after transplanting. If the soil is compacted, shallowly loosen the surface soil.

(4) Topdressing and Earthing Up: In the seedling bed, after thinning, apply 2000 kg of dilute manure water per mu; in August—September, broadcast another 200 kg of dry cow dung; after the snow melts the following spring, apply the above fertilizers again, but the amount can be appropriately increased. After transplanting, in February—March, apply dilute manure water once; in September—October and thereafter each year in March—April and September—October, apply fertilizer once each. Spring fertilizer should mainly be quick-acting fertilizer, and autumn fertilizer mainly farmyard manure, applying about 2000 kg per mu each time; the amount can be increased year by year. After fertilizing, earth up with fine humus soil in time.

(5) Adjusting Canopy Density: Whether using shade sheds or forest, attention should be paid to adjusting suitable light conditions to facilitate normal development of Coptis chinensis. Generally, in the year of transplanting, a canopy density of 70%—80% is suitable, then reduce by about 10% each year. In the harvest year, all shed covers and intercropped tree branches and leaves can be removed in June to increase light, inhibit aboveground growth, and increase rhizome yield.

4. Pest and Disease Control

(1) Powdery Mildew: Begins in late May, severely damages in July—August, mainly affecting leaves. Control methods: appropriately increase light and pay attention to drainage; in the early stage of disease, collect diseased leaves and burn them; spray with 80 international units of Qingfengmycin or 70% thiophanate-methyl 500-fold solution.

(2) Anthracnose: Begins in early May, damages leaves, and in severe cases causes the whole plant to die. Control methods: pay attention to cleaning the field in winter; spray with 1:1:100—150 Bordeaux mixture, or mancozeb 800—1000-fold solution.

(3) Southern Blight: Begins in June, severely damages in July—August, affecting the whole plant. Control methods: pull out and burn diseased plants, treat diseased holes with lime powder, or drench with carbendazim 800-fold solution.

(4) Slugs: Occur from March—November, bite and eat tender leaves, with severe damage on rainy days. Control methods: use vegetable poison bait to trap and kill; sprinkle lime powder in the early morning.

III. Harvesting and Processing

Coptis chinensis is generally harvested 5 years after transplanting, and is best dug from early November to before snowfall. When harvesting, choose a sunny day, dig up the whole plant, shake off the soil, cut off the fibrous roots and leaves to obtain the fresh rhizome, commonly known as “mao tuan”. The fresh rhizome should not be washed with water but dried directly; the drying method is mostly pit drying. Note that the fire must not be too strong, and stir frequently. When dried to the point of being easily broken, while hot put it into a slotted cage and shake off sand, fibrous roots and residual leaf stalks to obtain the dried rhizome. The fibrous roots and leaves, after drying and removing sand and impurities, can also be used as medicine. The residual leaf stalks and fine residue, after screening clean, can be used as veterinary medicine.

IV. Seed Saving Techniques

Coptis chinensis can flower and set seed 2 years after transplanting, but seeds from plants 3-4 years after planting are better in quality and greater in quantity. Generally in mid-May, when the fruit turns from green to yellow-green and the seeds become yellow-green, harvest in time. Seed collection should be done on a sunny day or a cloudy day without rain or dew; pick the fruit spikes from the stem, place them in a fine-mesh container, keep indoors or in a cool place, and after 2—3 days of after-ripening, rub out the seeds. Then mix the seeds with 2 times their volume of fine humus soil or fine sand and store them in layers.