Detailed Explanation of the Key Cultivation Techniques for Codonopsis pilosula Medicinal Herb
Codonopsis pilosula is the dried root of the Campanulaceae plant Codonopsis pilosula. It has the functions of tonifying the middle and boosting qi, enriching the blood and promoting fluid production. It is mainly produced in Shanxi, Hebei, the Northeast and other provinces, with Shanxi's Lu Dangshen being famous. It is now introduced and cultivated in Shandong, Henan, Anhui, Jiangsu and other provinces.
(1) Morphological Characteristics
Perennial herbaceous vine. The whole plant has white milky juice in cross-section and a distinctive odor. The root is long and cylindrical, sparsely branched, fleshy, with a surface ranging from grayish-yellow to brown; the upper part has fine dense ring lines, while the lower part has sparsely distributed transversely elongated lenticels. The root head is swollen and bears numerous tumor-like stem scars, commonly called the "lion's coiled head." The stem is slender and much branched, with fine white hairs on the young parts. The leaves are alternate, opposite, or falsely whorled; the leaf blade is ovate or broadly ovate, with a nearly heart-shaped base, hairy on both sides, entire or slightly wavy. The flowers are solitary and axillary; the calyx is 5-lobed and green; the corolla is bell-shaped, 5-lobed, yellow-green with purple spots. The capsule is conical; the seeds are numerous, small, elliptical, brown, and glossy. The flowering period is August to October, and the fruiting period is September to October.
(2) Growth Habits
Codonopsis pilosula prefers a cool and humid climate, is cold-tolerant, and avoids high temperatures and waterlogging; the seedling stage prefers shade and fears direct sun exposure, while the mature plant stage prefers light.
The seeds can germinate above 10°C, and the optimum germination temperature is 18-20°C. Fresh seeds can reach a germination rate of more than 85%, but seeds stored for over a year have an extremely low development rate or even completely lose their germination rate, so old seeds are not suitable for use as seed.
(3) Cultivation Techniques
1. Site selection and land preparation: It is advisable to choose sandy loam soil with deep soil layers, good drainage, and rich humus. Low-lying land, clay, and saline-alkali land are not suitable for planting, and continuous cropping should be avoided. The seedling-raising plot should be chosen in a semi-shaded, semi-sunny location close to a water source. Apply about 2000 kg of farmyard manure per mu, then plow, harrow finely, and level, and make flat beds 1.2 m wide. The transplanting site should be chosen in a sunny location, with sufficient base fertilizer applied, about 3000 kg of farmyard manure per mu, plus a small amount of phosphorus and potassium fertilizer; after application, plow deeply to 30 cm, harrow finely, and level, and make flat beds 1.2 m wide.
2. Propagation method: Use seed propagation, often by raising seedlings and transplanting, and rarely by direct sowing.
(1) Seedling raising: Generally sow during the rainy season in July-August or before freezing in autumn and winter; in areas with irrigation conditions, spring sowing can also be used, either in drills or by broadcasting. To make the seeds germinate earlier, use warm water at 40-50°C, put the seeds in while stirring, and when the water temperature is about the same as hand temperature, leave them for another 5 minutes, then transfer them to a gauze bag, wash several times with clean water, then place the whole bag on a sand pile indoors at 15-20°C, rinsing with clean water once every 3-4 hours; after 5-6 days the seeds will crack and can be sown. Broadcasting: Spread the seeds evenly on the bed surface, then cover with a little thin soil, just enough to cover the seeds, then lightly press to make the seeds and soil closely combine to facilitate emergence, using 1 kg of seed per mu. Drilling: Open shallow furrows 1 cm deep at a row spacing of 10 cm, spread the seeds evenly in the furrows, and similarly cover with thin soil, using 0.6-0.8 kg of seed per mu. After sowing, cover the bed surface with corn stalks, rice straw, or pine and fir branches to retain moisture, then water appropriately and keep the soil moist regularly. For spring sowing, plastic film can be used to facilitate emergence. When the seedlings are about 5 cm tall, gradually remove the covering; when the seedlings are about 10 cm tall, thin them at a plant spacing of 2-3 cm. Remove weeds as soon as they appear, and appropriately control water, preferably watering little but frequently.
(2) Transplanting: After the seedlings have grown for 1 year, transplant from mid-October to November in autumn before freezing, or from mid-March to early April in early spring after the soil thaws and before the young seedlings sprout. On the prepared bed, open furrows 15-20 cm deep at a row spacing of 20-30 cm; on hillside land, open furrows horizontally along the slope, place the seedlings obliquely in the furrows at a plant spacing of 6-10 cm with the buds pointing upward, then cover with about 5 cm of soil, using about 30 kg of seed roots per mu.
3. Field management
(1) Intertillage and weeding: Remove weeds as soon as they appear after emergence; loosen the soil shallowly, and stop after the rows close.
(2) Topdressing: Generally no topdressing is applied during seedling raising. After transplanting, usually apply human waste once before trellising, at 1000-1500 kg per mu, then earth up after application.
(3) Irrigation and drainage: After transplanting, irrigate promptly to prevent the seedlings from drying out and to ensure emergence; after survival, irrigate little or not at all to prevent excessive growth of the seedlings. In the rainy season, pay attention to drainage to prevent root rot.
(4) Trellising: The stems and vines of Codonopsis pilosula can grow to more than 3 m, so when the seedlings are 30 cm tall, trellises should be set up so that the stems and vines can climb and grow, which helps ventilation and light penetration, increases the area for photosynthesis, and improves disease resistance. Use local materials for the trellis, such as tree branches or bamboo poles.
4. Pest and disease control
(1) Rust disease: Occurs frequently in autumn and damages the leaves. Control method: Clean the field; in the early stage of the disease, spray with a 1000-fold solution of 25% triadimefon.
(2) Root rot: Generally occurs frequently when the soil is too wet and the temperature is high, and damages the roots. Control method: Crop rotation; promptly pull out diseased plants and disinfect the diseased holes with lime powder; during the disease period, drench with an 800-fold solution of 50% thiophanate-methyl.
(3) Aphids and red spiders: Damage the leaves and young buds. Control method: Spray with an 800-fold solution of 40% dimethoate emulsion. In addition, there are also white grubs, cutworms and others that damage the roots.
(4) Harvesting and processing
Generally, after 1-2 years of transplanting, harvest in autumn when the aboveground parts wither. First cut off the stems and vines, then dig out the roots, shake off the soil, and dry them separately by thickness and size until soft; rub them by hand along the root or with a wooden board, then dry again, repeating 3-4 times until dry. The drying ratio is about 2:1. The product is best when the roots are thick and large, the skin and flesh are tight, the texture is soft and moist, and the taste is sweet.
(5) Seed retention techniques
Although annual plants can flower and set seed, the seed quality is poor and unsuitable for use as seed, so it is preferable to use seeds set by plants more than two years old as seed. Generally, the fruit matures in September-October; when the fruit turns yellowish-white and the seeds are light brown, seed collection can begin. Because the seeds mature unevenly, they can be harvested in stages and batches, sun-dried and threshed, cleaned of impurities, and stored in a dry, ventilated place.