Detailed Explanation of Key Points for Standardized Cultivation Techniques of Angelica sinensis
1 Site Selection and Land Preparation
1.1 Site selection. Choose sandy loam soil that is deep, loose, well-drained, fertile, and rich in organic matter. For seedling raising, it is best to choose a north-facing gentle slope with half shade and half sun; for transplanting, a wind-sheltered, sunny location is suitable, and continuous cropping should be avoided.
1.2 Land preparation. For the cultivation site, choose a field with deep soil. Before sowing, plow deeply 2~3 times, with a deep plowing depth of more than 25 cm, and accelerate soil maturation through sun exposure. Then, before planting, apply 2~3 tons/mu of decomposed farmyard manure and 30~50 kg/mu of compound fertilizer during land preparation, plow them into the soil as base fertilizer, and then shallow plow once more before sowing, make high beds 1~1.3 m wide, and open drainage ditches around them.
2 Propagation Methods
2.1 Direct sowing. Both drilling and dibbling can be used. For drilling, open horizontal furrows on the prepared bed surface in early May, with a row spacing of 30 cm and a furrow depth of 5 cm. The furrow bottom should be flat. Use 1~1.5 kg of seed per mu. For dibbling, dig holes on the bed surface in a plum-blossom pattern with a hole spacing of 27 cm, with a hole depth of 3~5 cm. The hole bottom should be flat. Sow 3~5 seeds per hole, using 0.5~1 kg of seed per mu, then cover with 1~2 cm of fine soil, and finally cover the furrows or holes with a thin layer of short grass or pine needles to help retain moisture.
2.2 Seedling raising and transplanting. Choose a north-facing gentle slope with half shade and half sun, and prepare the land into beds before sowing. Raise seedlings from late March to early April or in mid-July. Use drilling for seedling raising, which is convenient for management, or broadcast sowing. For drilling, open furrows across the prepared bed at a row spacing of 15~20 cm, with a furrow depth of about 3 cm. Evenly scatter the seeds into the furrows, cover with 1~2 cm of soil, level the bed surface, and cover with grass to retain moisture and shade light. The sowing rate is 4~5 kg per mu. Generally, seedlings emerge 10~15 days after sowing. When the seedlings are 1~2 cm tall, remove the covering and pull out weeds. Thin the seedlings while weeding, maintaining a plant spacing of 1 cm.
Seedlings raised from March to April are transplanted in June of the same year; seedlings raised in July are transplanted in March of the following year. The transplanting spacing is 20 cm x 20 cm, with 2~3 seedlings per hole, and 12,000~18,000 plants transplanted per mu. After planting, fill with soil and press firmly, then cover with fine soil, covering 2~3 cm above the root crown of the seedlings.
3 Field Management
3.1 Seedling protection for overwintering. Direct-sown seedlings need winter fertilizer before overwintering. Apply decomposed farmyard manure or compost into the holes for dibbling or the furrows for drilling, and cover with fine soil after application. For seedlings raised for transplanting, the seedling bed left in place is not given winter fertilizer; instead, cover the bed surface with fine soil to a thickness of 1~2 cm.
3.2 Thinning and final thinning. Both seedling-raised and direct-sown plants need thinning, removing overly dense weak seedlings. Thinning is often carried out together with intertillage. For dibbling, keep 2~3 seedlings per hole with a plant spacing of 3~5 cm, and final thinning is done when the seedlings are 10 cm tall. For drilling, final thinning is done at a plant spacing of 15~20 cm, leaving 6,500~7,000 plants per mu. For direct sowing, carry out the first thinning when the seedlings are 3 cm tall, and final thinning when they are 10 cm tall. For transplanted plants, carry out final thinning together with the first weeding, keeping 1 plant per hole and 6,000~9,000 plants per mu.
3.3 Intertillage and weeding. Direct-sown seedlings generally require 3~4 intertillage and weedings. The first 2 are carried out together with thinning and final thinning, the 3rd around early July, and the 4th around early August. Shallow cultivation is suitable during intertillage. During the 2nd and 3rd intertillage, bolting plants should be pulled out. The first weeding is carried out 30 days after transplanting, loosening the soil with a shovel or small hoe to a depth of 3 cm, breaking up crusting and removing weed seedlings. The second intertillage and weeding is carried out 60 days after transplanting, using a hoe to cultivate deeply 4~5 cm and remove all weeds. Take care to prevent disturbing roots and injuring seedlings. The third weeding is carried out before Angelica sinensis closes its rows. When Angelica sinensis closes its rows, use a hoe to cultivate deeply 7~8 cm, remove all weeds, take care to prevent disturbing roots and injuring seedlings, and at the same time earth up around the roots. Afterward, pull out weeds whenever they appear.
3.4 Topdressing. Do not apply excessive nitrogen fertilizer at the seedling stage, so as to avoid excessive seedling growth causing early bolting. In the middle and late growth stages, appropriately increase the application of human and livestock manure water or compost, etc., at 1 ton per mu.
3.5 Removing flower bolts. When planting, choose late-maturing varieties that are not prone to bolting, and adopt various agronomic measures to reduce the early bolting rate. For plants that bolt early, prune them promptly, otherwise it will reduce the quality of the medicinal material, and at the same time consume large amounts of water and fertilizer, greatly affecting the plants. They should be removed early and completely.
3.6 Irrigation and drainage. During the seedling stage of Angelica sinensis, water appropriately during drought to keep the soil moist, but do not irrigate heavily. Drain accumulated water promptly during the rainy season to prevent root rot.
4 Pest and Disease Control
4.1 Diseases. Mainly root rot and powdery mildew. 1 Root rot. In the early stage, there are no obvious symptoms in the aboveground part. The infected tissue first turns brown, then rots and becomes water-soaked. It is easily removed by gently wiping with the hand, forming sunken spots on the roots. In the later stage, the entire root rots and has a foul odor, while the aboveground part wilts and dies. Control methods: choose disease-free, healthy seedlings; promptly pull out and destroy diseased plants, and disinfect the soil in diseased holes locally with 400~500 g of plant ash or 200~300 g of quicklime. It can also be controlled by drenching roots with 500~800 times dilution of 40% Genfuning, 0.5 kg per plant. Soak seedlings for 30 minutes in 1,000 times dilution of 50% carbendazim wettable powder. 2 Powdery mildew. It occurs during high temperature and dry conditions in summer. Grayish-white powdery diseased spots appear on the surface of affected leaves, causing the leaves to turn yellow and wither. Control methods: promptly pull out and burn diseased plants; in the early stage of disease, spray 1,000 times dilution of 50% thiophanate-methyl.
4.2 Insect pests. Mainly black cutworm, white grub, aphid, and red spider mite. 1 Black cutworm and white grub damage roots and stems. Control methods: deeply plow the land in winter, clear weeds, and eliminate overwintering eggs; apply decomposed stable manure and compost, and cover with soil after application to reduce the number of eggs laid by adults. Use 100 g per mu of 90% crystalline trichlorfon mixed with wheat bran to make poisoned bait for trapping and killing. 2 Aphids and red spider mites damage the young leaves of new shoots. Control methods: spray with 800~1,500 times dilution of 40% dimethoate emulsifiable concentrate.
5 Harvesting and Processing
Autumn direct-sown Angelica sinensis is harvested in the 3rd year after sowing, while transplanted plants are harvested around late October of the same year; dig them when the plants turn yellow and withered. During harvesting, take care not to break or injure the roots. Shake off the mud and sand from the roots, air-dry for 2~3 days until the roots become soft, cut off the stems and leaves, divide them according to root size and tie them into small bundles, hang them head-down on a curing rack, and smoke-cure them slowly with smoke and fire. During smoking, pay attention to indoor ventilation and turn the roots frequently. After drying, rub off the fibrous hairs, trim off excessively fine rootlets, and they are ready for sale.