How to Grow Atractylodes macrocephala? A Detailed Guide to Cultivating the Medicinal Herb Bai Zhu
Bai Zhuis a plant of the Asteraceae family; the dried rhizome of Atractylodes macrocephala is used medicinally, also known as Yu Zhu, Zhe Zhu, Sheng Shai Zhu, etc. It has the functions of tonifying the spleen and strengthening the stomach, drying dampness and promoting diuresis, stopping sweating and preventing miscarriage. It is mainly produced in Zhejiang and Jiangsu, and cultivated in more than 20 provinces including Jiangxi, Henan, Anhui, Sichuan, Hunan, Hebei and Fujian.
(1) Morphological Characteristics
Perennial herb, plant height 30-80 cm. The rhizome is thick and large, slightly fist-shaped, grayish-yellow; the stem is erect, woody at the base. Leaves are alternate; the lower stem leaves have long petioles, with blades 3-parted or pinnately 5-parted, margins with spiny teeth; the upper stem leaves have gradually shorter petioles, blades undivided, elliptical or ovate-lanceolate. The flower head is solitary at the branch tips, large; involucral bracts in 7-8 layers, the base surrounded by a whorl of pinnately parted leaf-like involucre; numerous flowers borne on a flat receptacle, all tubular flowers, corolla purple; fruit oblong-elliptical, slightly flattened, surface covered with fine hairs, pappus feathery. Flowering period July-September, fruiting period September-November.
(2) Growth Habits
Bai Zhu prefers a cool climate and fears high temperatures and excessive moisture. The suitable temperature for rhizome growth is 26-28°C, and mid-August to late September is the period of fastest rhizome expansion.
Seeds germinate easily; the optimal germination temperature is around 20°C, and they require relatively more water, generally absorbing water at 3-4 times the seed weight. Seed viability is 1 year.
(3) Cultivation Techniques
1. Site selection and land preparation: Choose sandy loam soil with good drainage, on high slopes, ventilated and cool, and capable of irrigation. Apply 3000 kg of farmyard manure per mu as base fertilizer (if no farmyard manure, apply more chemical fertilizer), 70 kg of phosphate fertilizer (25 kg of diammonium), 30 kg of nitrogen fertilizer; alternatively, directly apply 40-60 kg of three-element compound fertilizer (nitrogen, phosphorus, potassium). Deep plow 20 cm, rake level and fine, make beds 1-1.2 m wide. Combine soil disinfection with land preparation. Avoid continuous cropping.
2. Propagation method: Use seed propagation; in production, the seedling-raising and transplanting method is mainly used.
(1) Seedling raising
Select plump, pest-free new seeds, soak in warm water at 25-30°C for 12 hours (add carbendazim to the water to prevent disease), remove and air-dry slightly; either drilling or broadcasting can be used. Before sowing, first spray water on the bed; wait for the water to seep down and the surface to dry slightly, then open furrows at a row spacing of 15 cm, furrow depth 4-6 cm, sowing width 7-9 cm, with a level furrow bottom. After sowing, cover with soil and level, press lightly. Use about 8 kg of seed per mu. With suitable temperature, seedlings emerge about 10 days after sowing. In the south, transplant before winter; in the north, transplant in spring.
(2) Transplanting
Select planting stock that has not bolted or flowered in the current year, with robust main buds and small, uniform rhizomes. Trim off fibrous roots, open furrows 10 cm deep at a row spacing of 25 cm, place the planting stock into the furrows at a plant spacing of about 15 cm, with bud tips facing up and level with the ground surface. After planting, press lightly on both sides; after all are planted, water thoroughly once. Generally about 100 kg of fresh planting stock is needed per mu.
3. Field management
(1) Management of the planting stock field: After seedlings emerge, weed promptly and thin seedlings to a plant spacing of 4-6 cm. If the weather is dry, water in the early morning and evening to combat drought. If bolting and flower buds appear in the later growth stage, remove them promptly.
(2) Field management: After seedlings emerge, there are many weeds in the field, so cultivate and weed frequently; the first few cultivations can be deeper, and later should be shallow hoeing. After mid-May, the plants enter the vigorous growth period and generally are no longer cultivated; if there are weeds between plants, pull them by hand. In mid-June the plants begin to form flower buds; generally in early to mid-July, after budding and before flowering, remove the buds in batches (except for seed-production areas); bud removal helps increase the yield and quality of Bai Zhu rhizomes. During the growth period, Bai Zhu needs sufficient water, especially during rhizome expansion; if drought occurs, irrigate promptly. If water accumulates after rain, drain it promptly. Before and after budding, apply a top dressing once, applying 20 kg of urea and 30 kg of compound fertilizer per mu in furrows between rows, then cover with soil and water. One week after bud removal, apply another top dressing. It should be noted that field operations such as weeding, loosening soil, fertilizing and bud removal should all be carried out after the dew has dried.
4. Pest and disease control
Bai Zhu has relatively many pests and diseases; the common ones are as follows.
(1) Damping-off: Occurs easily under low temperature and high humidity, mostly in planting stock fields, damaging rhizomes. Control methods: reduce field humidity; in the early stage of disease, drench with 50% carbendazim 1000-fold solution.
(2) Iron leaf disease, also called leaf blight. Begins in April, especially severe from June to August, damaging leaves. Control methods: remove diseased plants; in the early stage of disease, use 1:1:100 Bordeaux mixture, preferably spraying continuously for one week; only then can the pathogen be thoroughly eliminated; in the later stage, spray with 50% thiophanate or carbendazim 1000-fold solution.
(3) Southern blight, also called rhizome rot. The onset period is the same as above, damaging rhizomes. Control methods: rotate with gramineous crops; remove diseased plants and disinfect diseased holes with quicklime powder; disinfect soil with Trichoderma harzianum before planting.
(4) Root rot, also called rotten root disease. The onset period is the same as above, especially severe when humidity is high, damaging roots. Control methods: breed disease-resistant varieties; rotate with gramineous crops, or practice paddy-upland rotation; before planting, soak seeds in 50% carbendazim 1000-fold solution for 5-10 minutes; in the early stage of disease, drench the affected area with 50% carbendazim or 50% methyl thiophanate 1000-fold solution. In areas with severe underground pest damage, drench with 1000-1500-fold dimethoate or 800-fold trichlorfon.
(5) Rust disease: Begins in May, damaging leaves. Control methods: clean the field; in the early stage of disease, spray with 25% triadimefon 1000-fold solution.
(4) Harvesting and Processing
From late October to mid-November, when the stems and leaves of Bai Zhu begin to wither, dig out the rhizomes and cut off the stems. Winter temperatures are low, making sun-drying difficult, so they can be sliced and sun-dried. Most are dried by heat; initially the fire can be stronger, with the temperature controlled between 90-100°C. When moisture appears, lower the temperature to 60-70°C, turn once every 2-3 hours, then dry for another 2-3 hours. When the fibrous roots are dry, take out and pile to "sweat" for 5-6 days, allowing internal moisture to seep to the surface, then dry for another 5-6 hours, with the temperature controlled between 50-60°C, turning once every 2-3 hours. When 80% dry, take out and pile again to "sweat" for 7-10 days, then dry until fully done, and rub off the residual stems and fibrous roots. The product is best when large, thick-fleshed, without tall stems, without fibrous roots and without insect damage.
(5) Seed Preservation Techniques
Bai Zhu seed preservation can be divided into plant selection and plot selection; the former can improve seed purity. Generally in July-August, select robust plants with small branches, large leaves and flat, large flower buds as mother plants for seed production. Remove late-opening or early-opening flower buds, and keep 5-6 flower buds per plant. Harvest seeds in early to mid-November. On a sunny day, dig up the plants and cut off the underground rhizomes; tie the aboveground parts into small bundles and hang them upside down under the eaves to after-ripen for 20-30 days, then thresh, winnow away the fuzz and shriveled seeds, put into cloth bags or gunny bags, and hang in a ventilated, cool place for storage. Note that Bai Zhu seeds must not be sun-dried for too long, otherwise the germination rate will be reduced.