The Latest Cultivation Techniques and Methods Tutorial for Cynanchum paniculatum

Cynanchum paniculatum is the root and rhizome or whole plant with roots of the perennial herbaceous plant Cynanchum paniculatum of the family Asclepiadaceae. It is distributed across most parts of the country, mostly growing wild on hillsides or in roadside grass. It is mainly produced in East China, Guizhou, Guangxi and the Northeast, among other places. In recent years, medicinal herb growers in East China and other areas have succeeded in trials of converting wild plants to domestic cultivation and have carried out small-scale planting.

Growth Habits

Cynanchum paniculatum is a perennial upright herb reaching 60-80 cm in height. It has strong adaptability to climate and can grow normally in sunny mountainous areas and plains both north and south of the Yangtze River. It prefers a warm, humid environment but is intolerant of waterlogging. It has strong heat and cold tolerance: it can still grow normally when temperatures exceed 30°C, and its underground rhizomes can survive at -20°C. Plants over 2 years old can flower and set seed, but the seed-setting rate is relatively low. The seeds germinate easily, with an optimal germination temperature of 25°C-30°C, a germination rate of over 90%, and a seed lifespan of 2-3 years.

Cultivation Techniques

Site selection and land preparation: It is best to choose fertile sandy loam rich in humus, with deep soil and good drainage. Apply 2000-3000 kg of fully decomposed farmyard manure per mu, plus 30 kg of superphosphate as base fertilizer, till to a depth of about 30 cm, level and harrow fine, and make raised beds 130 cm wide and 6-10 m long, or as determined by the terrain. The bed surface should be shaped like a turtle shell. Finally, open large and small drainage ditches according to local conditions.

Propagation Methods

Two methods are commonly used in production: seed propagation (raising seedlings for transplanting) and division propagation.

1. Seed propagation. Select seeds from plants over 2 years old that are mature, plump and generally have a germination rate above 80%. For spring sowing, the sowing period is February to March; in low-temperature areas, autumn sowing from September to November is mostly adopted. Make raised beds 130 cm wide in the seedling nursery, open furrows at a row spacing of 15 cm for drilling, with a furrow depth of about 2 cm and a level furrow bottom. Sprinkle a layer of decomposed compost powder in the sowing furrow and pour on human and livestock manure water. Mix the seeds with plant ash and evenly scatter them in the sowing furrow. After sowing, cover with a layer of burnt soil or humus soil, and finally cover with grass to keep the bed surface moist. Seedlings emerge after 2-3 weeks. Remove the covering grass promptly after emergence. After the seedlings are uniform, thin and final-thin several times at different spacings, and promptly loosen the soil, apply topdressing and remove weeds. After careful cultivation for 1 year, carefully dig up the seed roots for transplanting after the plants die back in winter and before they sprout the following spring. Plant at a spacing of about 22-26 cm between plants and rows, with 2 plants per hole. When planting, straighten the root system, cover with soil and press firm, and pour manure water to settle the roots. The seeding rate for seed seedling propagation is 1.5-2.5 kg per mu, which can be transplanted to expand planting in 8-10 mu of field.

2. Division propagation. In early spring in March, dig up the underground rhizomes of Cynanchum paniculatum and select fresh rhizomes that are robust, white in color, with dense nodes and free of pests and diseases. Cut off the excessively long fibrous roots for medicinal use, leaving roots about 5 cm long. Then, according to the number of bud eyes, cut the rhizomes and separate the mother clumps into several plants, each retaining 1-2 bud eyes. The planting method is the same as for seedling transplanting. Each mu of field requires 45-80 kg of rhizomes for planting, and the seed rhizomes from each mu of mother field can be transplanted to about 10 mu of field.

Field Management

1. Thinning and filling in seedlings. In the seedling nursery, seedlings emerge 20-25 days after sowing. After the seedlings are uniform, start thinning when they are about 3 cm tall, and continue 2-3 more times afterward. When the seedlings are 7-10 cm tall, final-thin by the method of leaving seedlings in staggered positions, with a plant spacing of 6-10 cm and a row spacing of about 15 cm. If gaps are found during thinning, replant promptly.

2. Cultivation and weeding. One week before land preparation, spray the ground with herbicides such as Roundup, then prepare the land, open furrows and sow. Before emergence, cover the bed surface with a layer of raw soil or burnt soil. During the seedling stage, temperatures are relatively low and plants grow slowly, but weeds are especially harmful to Cynanchum paniculatum at the seedling stage. It is necessary to seize the opportunity to loosen the soil and weed 2-3 times before the rows close (when seedlings are 15-20 cm tall). When loosening the soil, loosen shallowly near the plants and deeper between the rows to avoid damaging the roots. Protect the seedlings well, prevent them from being pressed by clods of soil, and never injure the stems. Soil compaction after rain should also be loosened in time.

3. Earthing up around the base. After the transplanted seedlings survive, when the seedlings are 20 cm tall, mix livestock manure with burnt soil or other fertile soil free of weed seeds, crush it, and cover the base of the plants to a thickness of no more than 3 cm. This can promote the growth of the underground parts of the plants and increase yield.

4. Reasonable topdressing. In addition to applying sufficient base fertilizer before land preparation, topdressing must be applied appropriately 2-3 times. The first time is before Qingming, when the seedlings are 3-6 cm tall. Apply 1500 kg of dilute human and livestock manure water per mu (or 4 kg of urea mixed with water) to the roots to promote seedling growth. The second time is in early to mid-May. Apply nitrogen, phosphorus and potassium fertilizers together: mix 8-12 kg of high-quality NPK compound fertilizer with 25 kg of decomposed cake fertilizer powder and apply in holes 10 cm away from the plants, to meet the plants' need for branching and leaf growth. The third time is around Mangzhong (Grain in Ear). Use the method of fertilizing according to seedling condition, generally mainly with decomposed human and livestock manure water, biogas slurry and other farm organic fertilizers. Each topdressing should be combined with cultivation and weeding. In addition, if a potassium dihydrogen phosphate solution or other trace-element fertilizer or hormone is used for foliar topdressing 2-3 times, it can improve the plants' disease resistance and lodging resistance and increase yield.

5. Drainage and irrigation. After the seeds germinate, pay attention to watering to keep the soil moisture moderate. In case of drought, water in time to resist drought and prevent the plants from drying out and dying. During the rainy season when rainfall is concentrated, prevent waterlogging and root rot, and pay attention to clearing ditches and draining water in time.

6. Trellising. Along the direction of the bed furrows, erect 2 bamboo or wooden stakes every 6 m (wooden stakes about 120 cm tall). At heights of 25 cm, 45 cm and 65 cm above the bed surface, run 2 lines of cloth strips or plastic rope each, and place the plants prone to lodging against both sides of the ropes to secure them. Timely trellising solves the problem of Cynanchum paniculatum being prone to lodging, which leads to low yield. It promotes normal growth and branching, increases the number of branches, thickens the stems, increases plant height, and thereby increases yield.

7. Seed saving. Strengthen management of the seed field to avoid premature lodging of the plants. Apply potassium dihydrogen phosphate as foliar topdressing before flowering, or appropriately spray a compound fruit-setting agent during flowering, which can effectively increase the fruit-setting rate and promote robust seed growth. The fruits generally mature in September. Because the follicles dehisce automatically after maturing and the seeds then drift away with the wind, they should be harvested in time. When the follicles turn yellow-green and are about to dehisce, harvest them in stages and batches in time. Put the harvested fruits in a shallow tray and rub them to remove the fruit shells and seed plumes. Select mature, plump, brown seeds and store them in a dry, cool place, or store them in kraft paper bags and cloth bags. During storage, pay attention to turning and sun-drying them frequently to prevent adult and larval cadelle beetles from eating the seeds.

Pest and Disease Control

1. Diseases. Cynanchum paniculatum generally rarely suffers from diseases, but attention must be paid to the harm of root rot, in which affected roots turn black and rot. The disease generally begins in early May, is severe from June to July, and can continue until the end of October. Poor drainage or low-lying terrain favors its occurrence. Control methods: drain water and loosen the soil promptly during the rainy season to reduce humidity among the plants on the ground; promptly pull out diseased plants and treat the diseased holes with lime to prevent spread. For chemicals, use 50% carbendazim 500-fold solution, 70% hymexazol 500-fold solution, or 58% metalaxyl wettable powder 600-fold solution, 25% root rot spirit wettable powder 500-fold solution, or 75% chlorothalonil wettable powder 600-fold solution to drench the roots of the plants to reduce the harm.

2. Insect pests. Mainly aphids and stink bugs, which mainly harm the stems and leaves of young tender plants and pierce and suck fruit juice. Control methods: spray 40% omethoate 2000-fold solution per mu, or dilute 20 ml of 20% fenvalerate with 50 kg of water and spray the plants, once every 7 days, for 2-3 consecutive times to control the pests.

Harvesting and Processing

Cynanchum paniculatum propagated by division can be dug up in the same year after planting. Those propagated by seed are dug up after 2 years. For those not needed as seed roots, dig up the whole plant with roots, wash off the soil, and sun-dry. For those needed as seed stock, harvest the stems and leaves and the roots separately in autumn and spring. After harvesting, remove soil and impurities from the stems and leaves, sun-dry until half dry, tie into small bundles, then sun-dry or dry in the shade. Root harvesting is generally done in early spring of the following year together with sowing; cut the seed roots to keep as seed stock, and wash the remaining roots, remove impurities, and sun-dry them for sale as medicinal material. The dried whole plant stems and leaves are gray-green; the dried roots and rhizomes are dark brown, brittle and easily broken. Those that are dry, plump, correct in color, free of impurities and strong in odor are considered the best quality.