Detailed Explanation of Key Techniques for High-Yield Cultivation of Corydalis yanhusuo

Corydalis yanhusuo, also known as Xuanhu, Yanhusuo, etc. Its underground rhizome is used as medicine, and it has the effects of activating blood circulation, regulating qi, and relieving pain. It mainly treats pain in the heart, abdomen, waist, and knees, traumatic injuries, pain caused by blood stasis, irregular menstruation, and other conditions. The main producing areas are Zhejiang, Jiangsu, Anhui, Jiangxi, Liaoning, Shaanxi and other provinces.

Morphological Characteristics

Corydalis yanhusuo is a perennial herbaceous plant with persistent roots, 9-20 cm tall, smooth and hairless throughout, with underground stolons and tubers. The stolons have 3-5 nodes and are distributed 3-5 cm below the soil surface. The tubers are oblate, 0.7-2 cm in diameter, brownish-yellow on the outside and yellow inside. The aboveground stem is slender and brittle, slightly fleshy, single or branched above, with one scale above the base of the stem. The basal leaves are the same shape as the stem leaves. The stem leaves are alternate, bipinnately trifoliolate, with leaves entire or deeply lobed; the lobes are lanceolate or narrowly ovate, 1.2-3 cm long and 3.5-8 mm wide, with obtuse or bluntly acute tips and entire margins. The raceme is terminal or opposite the leaves, 3-6.5 cm long; the bracts are ovate, narrowly ovate, or obovate, 8 mm long. The raceme has reddish-purple flowers borne horizontally on slender pedicels; the pedicels are about 6 mm long. There are 4 petals; the 2 outer ones are slightly larger, pink at the margins and blue-purple in the center; the upper one extends at the tail into a long spur, with the spur accounting for about half of the total length; the 2 inner petals are narrower and smaller than the 2 outer ones, blue-purple at the upper end and fused, pink at the lower part. There are 6 stamens, with the filaments united into two bundles, each bundle bearing 3 anthers. The ovary is flattened-columnar, about 6 mm long; the style is slender and short, with 2 stigmas, resembling a small butterfly. The fruit is a capsule.

I. Growth Habits

Corydalis yanhusuo prefers a warm and humid environment. It is cold-tolerant and afraid of drought. The suitable growth temperature is 20-30°C. Soil requirements: loose, fertile sandy loam rich in organic matter. Continuous cropping is avoided.

II. Land Preparation and Fertilization

Select a field with high terrain, good drainage, and loose, fertile soil, and carry out intensive cultivation. In combination with land preparation, apply sufficient base fertilizer: 3000 kg of farmyard manure per mu and 50 kg of compound fertilizer containing 15% each of nitrogen, phosphorus, and potassium. Then make raised beds 1.5 m high.

III. Planting

In production, Corydalis yanhusuo is propagated by corms. The sowing period is September to October. At sowing time, first use a drill to open shallow furrows on the prepared bed surface, then sow the Corydalis yanhusuo seed corms in the furrows. Row spacing and plant spacing are 20×10 cm. The sowing depth is 5 cm. Too deep is not conducive to emergence, while too shallow results in smaller newly formed upper corms. The sowing rate is 50 kg per mu.

IV. Field Management

Xuanhu emerges around the Beginning of Spring. After full emergence, attention should be paid to intertillage and weeding. For large-scale planting, soil treatment with a medicinal-field herbicide should be carried out before emergence, which can effectively control various weeds. Water during drought, and drain during rainy weather. Around Grain Rain, apply a topdressing once: 10 kg of urea and 10 kg of potassium dihydrogen phosphate per mu.

V. Pest and Disease Control

Downy mildew occurs at the seedling stage and damages the leaves of Corydalis yanhusuo. It can be controlled before onset or in the early stage with 1:1:150 Bordeaux mixture or phosethyl-Al. For sclerotinia, spray with 65% mancozeb 500 times dilution in the early stage of onset. For underground pests, use phoxim for control.

VI. Harvesting and Processing Corydalis yanhusuo is harvested in May of the second year after planting, after the underground stems and leaves wither. The excavated underground corms of Corydalis yanhusuo are cleaned of soil, divided into two grades by size, placed in boiling water and boiled for 5 minutes while being stirred constantly. When the inside of the corms turns yellow, remove them, dry them in the sun or by heat, then remove the outer skin and all impurities. They are then ready to be sold as medicine. The yield is 100 kg of dry product per mu.