Cultivation Methods and Key Technical Points for Codonopsis tangshen

Codonopsis is a perennial herbaceous plant of the Campanulaceae family. Its main chemical constituents are saponins, alkaloids, polysaccharides and volatile oils. Its root is used medicinally; it can tonify the middle and augment qi, strengthen the spleen and benefit the lungs; it treats weakness of the spleen and lungs, shortness of breath and palpitations, asthmatic cough due to deficiency, and internal heat with wasting and thirsting, among other conditions. Codonopsis is a valuable Chinese medicinal material with relatively high medical value. It is not only used in large quantities as a raw material for prescriptions and patent medicines, but is also widely used in the health beverage and green food industries, and market demand is relatively large.

There are many types of Codonopsis, including Lu Codonopsis, Chuan Codonopsis, Codonopsis pilosula var. modesta, Dong Codonopsis, Codonopsis tubulosa and Chai Codonopsis. Among commercial Codonopsis, Lu Codonopsis, Chuan Codonopsis and Codonopsis pilosula var. modesta are of the best quality. Chuan Codonopsis is the root of the Campanulaceae plant (Codonopsis tangshen Oliv.). It is mainly distributed in Sichuan, Chongqing, Hubei and Guizhou. Within Chuan Codonopsis there are several cultivated varieties: Miao Codonopsis, Ban Codonopsis and Luo Codonopsis. This article mainly introduces the cultivation techniques for Miao Codonopsis.

1 Botanical Characteristics

Herbaceous vine, the whole plant with white milky latex and fragrance. Root a long conical shape, branched, cream-colored. Stem vine twining, hairless. Leaves opposite, leaf blades ovate to oblong-ovate, margins wavy or with shallowly wavy rounded serrations, leaf surface green, smooth and hairless, leaf underside powdery green, covered with rough downy hairs. Flowers solitary, terminal or axillary; calyx green, deeply 5-cleft, lobes lanceolate, apex acute; corolla bell-shaped, pale yellowish-green, with purple markings inside; capsule berry-like, flattened round, not dehiscing when mature, persistent calyx relatively short. Seeds small, oblong, brown, glossy. Flowering period July to August, fruit ripening period September to October.

2 Biological Characteristics

2.1 Biological Characteristics

The germination rate of Codonopsis seeds is above 70%. Suitable temperature, air and moisture are necessary conditions for seed germination. 15-25°C is the optimum temperature for Codonopsis seed germination. Under suitable conditions, seedlings begin to emerge 20-25 days after sowing. For autumn-sown plants, the aboveground part dies back in November to December, and the underground part enters the overwintering state; in March of the following year it begins to sprout and emerge, with March to July being the vegetative growth period, July to August the flowering period, and September to October the fruit ripening period. Codonopsis can be rotated with Scrophularia ningpoensis, rhubarb, Aristolochia and corn, and continuous cropping is not suitable. Land that has grown Codonopsis must wait 2-3 years before it can be planted again; otherwise, there will be more pests and diseases and low yields.

2.2 Climate

Chuan Codonopsis prefers a slightly cool and moist climate, and is mostly distributed in mountainous areas above 1000 m, being most suitable at 1500-2500 m. Annual rainfall in the production areas is generally above 1200 mm; the highest summer temperature is below 30°C, the lowest winter temperature is within -15°C, and the frost-free period is about 180 days. In lower-altitude flatland areas, because the summer temperature is too high and lasts too long, not only does the aboveground part tend to wither, but diseases also occur easily, and it cannot grow normally. Codonopsis prefers a shaded and moist environment during the seedling stage, but during the growth stage it should not be excessively moist, nor should sunlight be too strong; cultivation on shaded slopes or semi-shaded slopes with only half a day of sunlight is most suitable.

2.3 Soil

Codonopsis is a deep-rooted plant, and the medicinal part is the thick and long main root, so it is suitable for cultivation in land with deep, fertile soil and good drainage. Generally, mountain oily sandy soil or mountain sandy loam rich in humus is better. Soil with a pH of 6.5-7.5, deep soil layers, relatively fertile, good structure and easy to cultivate is best. Soil that is too clayey and places prone to water accumulation are not suitable for cultivation.

3 Cultivation

3.1 Propagation Methods

Chuan Codonopsis is propagated by seed, by raising seedlings and transplanting, or it can also be direct-sown. Codonopsis generally flowers and fruits in the second year of planting; it is best to collect plump, well-filled seeds from 3-year-old plants for propagation. In September to October, when the fruit skin is slightly purplish-red, partly split, and the seeds turn yellowish-brown, harvest them, pile them indoors to after-ripen for several days, and once most of the fruits have split, dry them in the shade and rub out the seeds for later use. Old seeds cannot be used for planting.

3.2 Land Selection and Preparation

Chuan Codonopsis is suitable for cultivation on virgin land or fallow land, and continuous cropping is not suitable. The shrubs and weeds on the plot selected in winter should be spread on the ground and burned, then turned into the soil as base fertilizer. If cultivated soil is used for planting, it is best to deep-plow once before sowing or transplanting, turn the base fertilizer into the soil, remove weeds and stones, then rake fine and level to make beds.

3.3 Raising Seedlings and Transplanting

The seedling nursery should be finely plowed and harrowed so that the soil is fine and loose. If conditions permit, apply decomposed compost and plant ash as base fertilizer; if these fertilizers are not available, 50 kg of ammonium phosphate or compound fertilizer per mu can be applied as base fertilizer. For seedling raising, both spring sowing and autumn sowing are possible, with autumn sowing being better. Spring sowing is from late March to early April, and autumn sowing is from mid-September to early October. Before sowing, open beds 1.3 m wide on the prepared land, mix the seeds into seed ash, and sow evenly on the beds; both drilling and broadcasting are acceptable. For drilling, the seeding rate is 1.5-2 kg per mu; for broadcasting, the seeding rate is 2-2.5 kg per mu. After sowing, cover with a thin layer of soil, just enough to cover the seeds. After sowing, pay attention to appropriate watering and keep the soil moist regularly to facilitate seed germination and seedling emergence. If conditions permit, it is best to cover with a layer of wormwood stalks or grass after sowing, and remove it after seedlings emerge. After emergence, careful management is required, and appropriately apply dilute human and livestock manure water to promote seedling growth. When seedlings are 5-7 cm tall, weed and thin them, leaving 1 plant every 2 cm, and thereafter remove weeds whenever they appear. One mu of seedling nursery can transplant 5-7 mu.

Chuan Codonopsis seedlings can be transplanted after 2 years of raising. The transplanting period is mostly after the aboveground part dies back in autumn or before sprouting in spring. In high-altitude mountainous areas, seedlings can also be raised for 2 years before transplanting. Before transplanting, dig up the seedlings, tie them into small bundles of 30-50 plants, and place them in a shaded, moist place; it is best to finish planting the dug seedlings the same day. If the seedlings become dry, do not water them; instead bury them in moist soil for 1-2 days, and the seedlings will recover. Transplanting row spacing is 20-23 cm and plant spacing about 5 cm. When planting, depending on the length of the seedlings, open furrows of suitable depth on the bed, place the seedlings diagonally in the furrow without bending the tail, cover with fine soil, press firmly, then cover with soil level with the bed surface. For autumn transplanting in higher mountainous areas, the rhizome head should be 7-8 cm below the soil surface to prevent frost damage. Some high mountainous areas adopt raising seedlings for 2 years and then transplanting densely, which gives a relatively high yield per mu; this method can be appropriately promoted.

3.4 Direct Sowing

Sowing in both spring and autumn is acceptable, and autumn sowing produces better seedling emergence than spring sowing. Direct sowing is relatively simple; just drill or broadcast on the bed.

4 Field Management

4.1 Thinning and Replanting

For direct-sown plants, thin the seedlings in spring when they are 5-7 cm tall, leaving 1 plant every 3-5 cm. If there are missing or dead seedlings, replant promptly. For replanting, use a small bamboo stick to poke a small hole in the soil, place the seedling in it, cover with soil and press firmly.

4.2 Cultivation and Weeding

For both direct-sown and transplanted plants, weeding should be carried out in conjunction with thinning and replanting, because the seedlings are too small for cultivation. After the seedlings wither in autumn, use a small hoe to shallow-hoe between the rows while earthing up. In the 2nd and 3rd years after sowing, weeding should be done in both spring and autumn.

4.3 Topdressing

After weeding in spring, apply human and livestock manure water plus an appropriate amount of urea per mu to promote seedling growth; in autumn, apply 50 kg of ammonium phosphate or compound fertilizer per mu, and turn the fertilizer into the soil in conjunction with cultivation and earthing up.

4.4 Setting Up Supports

Codonopsis has relatively long vines. If allowed to grow freely, the vines and leaves overlap, blocking sunlight penetration and air circulation, which not only affects photosynthesis and reduces yield, but also makes the plants susceptible to disease. Therefore, in areas where materials are available, when the seedlings are about 30 cm tall, use bamboo or small tree branches as supports, inserting them between the rows slightly interlaced with one another, so that the Codonopsis vines can twine around them. Where materials are unavailable, some tall herbaceous plants should also be deliberately left as natural supports for the vines to climb.

5 Pest and Disease Control

5.1 Diseases

5.1.1 Rust occurs in July to August. After the plant is infected, the leaves wither and yellow and then die. Control methods: choose plots that are not excessively moist for cultivation; set up supports; in the early stage of the disease, spray with a 500-fold dilution of triadimefon or dithianon for control.

5.1.2 Root rot occurs in May to June, and is easily caused when there is a lot of rain, leading to root decay. Control methods: dispose of diseased roots and remnant plants, and pay attention to drainage; when the disease occurs, drench the planting holes with an 800-fold dilution of 50% thiophanate-methyl wettable powder.

5.2 Insect Pests

Flea beetles often occur after seedlings sprout in late spring; red spider mites occur more after June; aphids often occur in summer. All can be controlled by spraying with a 1000-fold dilution of 40% dimethoate emulsifiable concentrate.

6 Harvesting and Processing

6.1 Harvesting

Chuan Codonopsis must be dug up in full years. Seedling-raised and transplanted plants are harvested 1-2 years after planting; direct-sown plants generally require 3 years to harvest. If cultivation is continued without digging, the yield can also increase accordingly. Harvest in late autumn after the seedlings have withered; dig carefully and deeply, and extract the whole root to avoid the sap overflowing and forming black scars that affect appearance and quality. Harvested Codonopsis is generally graded into large, medium and small. The large and medium grades are washed and processed; the small ones can be processed for medicinal use or retained as transplanting seedlings.

6.2 Processing

After Chuan Codonopsis is graded and washed clean, it should be processed separately to avoid uneven drying. According to thickness, fineness and length, dry them separately in the sun, rub and knead them by hand on a wooden rubbing board, then dry in the sun, repeating 3-4 times until dry. If the weather is unfavorable, they can also be dried on a heated kang at about 60°C, likewise rubbing and kneading and spreading them on the heated kang to dry repeatedly several times until completely dry. For Chuan Codonopsis, generally 3 kg of fresh roots yields 1 kg of finished product, and 3-year-old plants yield 170-200 kg of finished Codonopsis per mu. Qualified Codonopsis is characterized by thick, sturdy root strips, a solid and firm texture, oily and moist appearance, strong aroma and flavor, little residue when chewed, no impurities, no insect damage, no mildew, and water-soluble extractives of no less than 32%.