Key Cultivation Techniques and Planting Methods for Costus Root (Saussurea lappa) Explained
Costus Root, also known as costus or Guangzhou costus, is a perennial plant of the Asteraceae family. Its underground rhizome is used as medicine, and it has the effects of strengthening the stomach and relieving bloating, regulating qi and relieving depression, and relieving pain and preventing miscarriage. It can promote the flow of qi and resolve stagnation, soothe the liver, and strengthen the stomach, and is used to treat all types of qi pain, food stagnation and accumulation, chest fullness and abdominal distension, vomiting, diarrhea, and dysentery. It is mainly produced in Sichuan, Yunnan, Guangxi, Guizhou, and other places.
Morphological Characteristics
Costus root is a tall perennial herb, 1—2 m tall, with a thick, cylindrical main root that has a distinctive aroma. The basal leaves are relatively large, with long petioles; the leaf blade is triangular-ovate or triangular, with a heart-shaped base, 30—100 cm long and 15—30 cm wide, with slightly wavy margins and sparsely arranged short prickles, and pubescence on both sides. The capitulum is solitary or in clusters of 2—6 at the stem tip or in leaf axils. All flowers are tubular florets, dark purple. The achene is oblong, ribbed, dark brown, with a plumose pappus at the upper end.
I. Growth Habits
Costus root is suitable for growing in high-cold mountainous areas at an altitude of 2700—3300 m. It is cold-tolerant and fertilizer-loving, and grows quickly in spring and autumn; it grows slowly in hot and rainy seasons. When the average daily temperature in summer is above 25°C and the maximum temperature reaches above 30°C, growth is poor and may even lead to death. Seedlings are afraid of strong light and need appropriate shading. The flowering period is July—August, and the fruiting period is August—October.
Costus root requires cool and humid climatic conditions. Because it is a deep-rooted plant, it is advisable to choose soil with deep, loose, fertile, and well-drained layers for planting. The soil pH is best in the slightly acidic to neutral range of pH 6.5—7.
II. Land Selection and Land Preparation
Fields previously planted with corn, potato, angelica, and other crops, with good drainage and fertile black oil-sand and white oil-sand soil, should be selected for planting. If the land is newly reclaimed, it must first be left fallow (burn off weeds and other plants on the virgin land). After the plot is selected, it must be deep-plowed 30 cm to turn weeds and other material into the soil for freezing and weathering. In February or March of the following year, plow again, open furrows at a row spacing of 40-45 cm, and apply about 60000 kg of decomposed manure such as barnyard manure and sheep manure per hectare as base fertilizer. To prevent the aroma of costus root from attracting underground pests, then turn the soil again (to make the manure and soil uniform), break it up, and rake it level, making beds 100-130 cm wide, or high beds 130 cm wide.
III. Sowing
Direct seeding with seeds is generally used, but when seeds are insufficient, vegetative propagation can also be used. Seed propagation is divided into spring and autumn sowing. Spring sowing is in early April, and autumn sowing is in August-September. Due to climatic differences, the sowing period varies from place to place.
Seed propagation: After the seeds are harvested, dry them in the sun and winnow them clean. For spring sowing, soak them in 30°C warm water, stir until cool, skim off the floating impurities and shriveled grains, and soak the plump seeds that sink to the bottom for 24 hours. Take out the seeds, dry them in the shade until half-dry, and then sow. After treatment, the seeds germinate earlier and emerge uniformly. About one week after sowing, seedlings can emerge. If the soil is dry and there are no irrigation conditions, the seeds should not be treated, so as to avoid water loss after sowing and loss of germination ability. For autumn sowing, the seeds are not treated, and hole sowing or drill sowing is used directly. In Yunnan, open furrows at a row spacing of 45 cm and a furrow depth of 2-3 cm. Spread the seeds evenly into the furrows, using 11.25-15 kg of seed per hectare, and cover with 3-5 cm of soil. For hole sowing, place 2-3 seeds every 6-8 cm in each furrow, using 7.5-15 kg of seed per hectare, and cover with soil after sowing. If the soil is relatively wet, covering with 5 cm of soil is sufficient. In Sichuan and Hubei, high-bed hole sowing is used. On a high bed 130 cm wide, open 4 rows of holes, with a hole spacing of 30 cm and a depth of 5-7 cm, sow 6-10 seeds per hole, cover with soil after sowing, and level the surface. If propagating with fine roots, plant at a spacing of 40 cm * 15 cm. Cover with soil just enough to cover the roots.
Vegetative propagation: Select fine roots that cannot be used medicinally, with a diameter of 3-5 cm, as propagation material. Although costus root has strong vitality and can emerge in one year, old roots have a poor shape, and many short fibrous roots cluster at the ends of fine roots, resulting in poor product quality.
Intercropping and relay intercropping: Because costus root seedlings are afraid of strong light, on land planted with potato, plant Angelica dahurica at 120 cm wide intervals. After the potato is harvested, plant corn, which provides shading and also yields grain. After that, shading is not needed for two years, because the costus root has already grown large.
IV. Field Management
1. Thinning and replanting: Costus root seedlings need to be thinned twice. The first thinning is when the seedlings are about 5 cm tall; the second is when the seedlings have 4 true leaves, leaving one seedling every 15 cm. For hole sowing, leave 2 seedlings per hole. Remove excess seedlings and replant them with soil at spots where seedlings are missing. In the last intertillage each year, inspect the seedlings and replant where any are missing to ensure a full stand of 180000 plants per hectare. Only a full stand can give a high yield.
2. Intertillage and weeding: After emergence, pull weeds whenever they appear. Because the seedlings are small and the roots are shallow, do not cultivate too deeply. When the seedlings have 6-7 true leaves, carry out the second shallow cultivation. Be sure not to damage the roots, otherwise the seedlings will die. The third weeding is in mid-to-late July. In the second year of costus root growth, when the overwintered seedlings turn green and produce new leaves, carry out the first hoeing. In mid-to-late July, carry out the second intertillage and weeding. In the third year, after the overwintered seedlings turn green and emerge completely, thin once, and weed and loosen the soil.
3. Topdressing: After costus root is established, in combination with the second intertillage and weeding, when 6 true leaves have grown in the first year, apply barnyard manure once at 15000-18750 kg per hectare. In July-August, apply 1:3 human feces and urine (feces and urine: water) or ammonium sulfate at 225-300 kg per hectare. In the second year, after the seedlings emerge completely, in combination with the first loosening of the soil and weeding, apply barnyard manure at 11250-15000 kg per hectare. During the growth of costus root, water when there is drought. After applying chemical fertilizer in the first year, water is needed.
4. Cutting flower stems and removing old leaves: After two years of growth, in July-August, in combination with intertillage and weeding, remove old leaves once each time, removing 4-5 old leaves per plant. The removed old leaves and young leaves can be used as feed. Around May of the second year after sowing, some plants bolt and flower. They should be cut off as soon as they begin to bolt. If they bolt again, cut again, so as not to affect root growth. In the third year, for seed production, except for seed plants, the remaining flower stems should also be cut off.
5. Hilling: In the first and second years, costus root needs hilling at the roots once each autumn. After the aboveground parts wither, hill with about 12 cm of soil, which can increase yield and quality.
V. Pest and Disease Control
The main pests and diseases of costus root are root rot and insect pests.
1. Root rot: The main cause of this disease is a high groundwater table and poor drainage, which make plants prone to root rot. Attention should be paid to drainage during the growing period to avoid its occurrence.
2. Aphids: Aphids are likely to occur in late summer and early autumn.
Control method: Spray with 0.5 kg of dimethoate emulsion added to 1000 kg of water.
3. Scale insects: They belong to the superfamily Coccoidea of the order Homoptera. They damage costus root throughout the year, and the season of fastest development is early autumn.