Detailed Explanation of Key Points for Standardized Cultivation Techniques of Kushen (Sophora flavescens)

Kushen (Sophora flavescens), also known as Kugu or Dihuai, is a perennial semi-woody plant of the Fabaceae family, with the effects of clearing heat and drying dampness, killing parasites, and promoting diuresis. Kushen is the dried root of the leguminous plant Sophora flavescens. Kushen has the effects of clearing heat and drying dampness, killing parasites, and promoting diuresis. Kushen is used to treat damp-heat, jaundice, dysentery, enteritis, skin itching and other conditions. The contraindication for using Kushen is that it should be avoided by those with deficiency-cold of the spleen and stomach. Kushen is incompatible with Veratrum (Lilu), and should not be used together with Veratrum.

I. Plant Characteristics

Deciduous semi-shrub, 1.5-3 m tall. Root cylindrical, outer bark yellowish-white. Stem erect, much branched, with longitudinal grooves; young branches sparsely hairy, becoming glabrous later. Odd-pinnate compound leaves, 20-25 cm long, alternate; 15-29 pairs of leaflets, leaf blades lanceolate to linear-lanceolate, 3-4 cm long, 1.2-2 cm wide, apex acuminate, base rounded, with short petiolules, entire margin, densely appressed pubescent on the underside; stipules linear. Racemes terminal, 15-20 cm long, short-hairy, bracts linear; calyx campanulate, flattened, 6-7 mm long, 5-lobed; corolla papilionaceous, pale yellowish-white; standard petal spoon-shaped, wing petals without auricles, equal in length to the keel petal; stamens 10, filaments free; ovary stalk finely hairy, stigma round. Pod linear, apex with a long beak, indehiscent at maturity, 5-8 cm long. Slightly constricted between seeds, appearing as indistinct bead-like segments, sparsely short-pubescent. Seeds 3-8, nearly spherical, black. Flowering period June-July, fruiting period July-September.

II. Growth Habits

Kushen prefers a warm climate and can be cultivated in plains, hills, and low mountain areas. It has low requirements for soil, but since Kushen is a deep-rooted plant, it is better to choose fertile, deep, well-drained sandy loam and clay loam for cultivation.

III. Cultivation Techniques

1. Site selection, land preparation and fertilization. For artificial cultivation of Kushen, choose loam, sandy loam, or humus loam with deep soil layers, good drainage, loose fertility, and sufficient sunlight for making beds. Apply 2000 kg of farmyard manure per mu. Adopt the large-ridge high-bed technique, bed width 130-140 cm, length as needed, bed height 10-12 cm, bed spacing 30 cm.

2. Propagation techniques. (1) Seed propagation. From July to September, when the Kushen pods turn dark brown, harvest them, sun-dry, thresh, winnow off impurities, and store in a dry place for later use. Seed treatment is required before sowing. Method: Soak seeds in warm water at 40°C-50°C for 10-12 hours, remove and drain slightly before sowing; or stratify with moist sand (seeds mixed with moist sand at 1:3) for 20-30 days before sowing. In addition, treating with 95%-98% concentrated sulfuric acid for 60 minutes can also increase the seed germination rate. In mid-to-late April, on the prepared high beds, dig holes 2-3 cm deep at a row spacing of 50-60 cm and plant spacing of 30-40 cm, sow 4-5 treated seeds per hole, cover with fine soil mixed with plant ash, keep the soil moist, and seedlings emerge in 15-20 days. When seedlings are 5-10 cm tall, thin them, leaving 2 strong seedlings per hole. Seedling transplanting can also be used. (2) Root division propagation. Can be sown in both spring and autumn. Autumn planting is done after leaf fall, and spring planting in late April, preferably when the ground temperature at 5 cm depth stabilizes above 15°C. Select 15-20 cm Kushen roots, each root must have 2-3 roots and buds, place flat at a row spacing of 30 cm, furrow depth 10 cm, cover with soil and press firm, water thoroughly.

3. Field management. (1) Cultivation and weeding. During the seedling stage, carry out cultivation, weeding, and earthing up, keeping the field free of weeds and the soil loose and moist to facilitate Kushen growth. (2) Topdressing. On the basis of applying sufficient base fertilizer, topdress twice a year. The first time in mid-to-late May when seedlings are 15 cm tall; the second time in early-to-mid August when seedlings are 50-70 cm tall. Apply topdressing timely and in appropriate amounts depending on plant growth conditions. (3) Drainage and irrigation. Pay attention to keeping the soil moist, water promptly during drought, and open ditches for drainage during the rainy season to avoid waterlogging and root rot. (4) Flower removal. Except for seed-producing plots, promptly prune off flower stems to avoid nutrient consumption.

IV. Harvesting and Processing

Roots can be dug 2-3 years after planting, in September-October after stems and leaves wither, or before seedling emergence in March-April. Dig out the whole plant, divide into individual roots according to the natural growth of the roots, remove the rhizome head and fibrous roots, wash clean of mud and sand, and sun-dry or oven-dry. About 700 kg of dried medicinal material can be produced per mu.

Kushen is distributed in Russia, Japan, India, Korea, and the northern and southern provinces and regions of mainland China, growing at altitudes of 1,500 m, mostly on hillsides, sandy areas, grassy slopes, shrub forests, and near fields. Traditional Chinese medicine holds that Kushen has the effects of clearing heat and drying dampness, killing parasites, and promoting diuresis.