What are the key cultivation techniques for Bupleurum (Chaihu)?
1. Site selection and land preparation. Bupleurum prefers a warm and humid environment, likes light, tolerates cold and drought, and fears waterlogging. For the cultivation site, sandy loam or loam with deep soil, loose and fertile texture, and good drainage should be selected. Before sowing, in combination with deep plowing and land preparation, apply 3500 kg of decomposed stable manure or farmyard manure per mu as base fertilizer, then make beds.
2. Propagation method
Bupleurum is mostly propagated by raising seedlings and transplanting them. Seedling raising is generally carried out from late March to late April. Before sowing, first soak the seeds in warm water at 40°C for 12 hours, then remove the shriveled seeds floating on the water surface, take out the plump seeds that sink to the bottom, and after drying them in the air, drill-sow them in shallow furrows opened horizontally on the prepared bed surface at a row spacing of 10 cm, with a furrow depth of 1.5 cm. Mix the seeds evenly with burned soil ash, spread them evenly into the furrows, cover with soil level with the bed surface, press slightly firm, water with a fine-hole watering can, and finally cover with plastic film or straw to help keep warm and moist. After the seedlings emerge uniformly, immediately remove the covering, strengthen management, cultivate for one year, and transplant out of the nursery the following spring for field planting.
From early to mid-March to early to mid-April of the following year, on the prepared bed surface, open furrows horizontally at a row spacing of 20 cm, with a furrow depth of 10 cm, place one seedling every 15 cm, with the root end close to the bottom of the furrow. The root system should be arranged smoothly and straightened, water thoroughly to settle the roots, then cover with soil level with the bed surface.
3. Field management
(1) Cultivation and weeding. In spring, when Bupleurum seedlings are more than 10 cm tall, loosen the soil and weed. After that, cultivate and weed once a month until the rows close.
(2) Topdressing. During the first year of vegetative growth, Bupleurum mainly needs nitrogen fertilizer and requires topdressing 3 times. The first time is in mid-to-late April, applying 2000 kg of decomposed human manure and urine per mu; the second time is in late June or early July, applying 2000 kg of human manure and urine and 100 kg of cake fertilizer per mu; the third time is after autumn when the plants wither, applying 2000 kg of decomposed stable manure or farmyard manure and 30 kg of superphosphate per mu. During the second year of reproductive growth, phosphorus fertilizer is mainly needed, and fertilization is also required 3 times. The first time is in early-to-mid April, applying 2500 kg of decomposed human manure and urine per mu, or 30 kg of urea; the second time is in late June, applying 40 kg of superphosphate or 200 kg of cake fertilizer per mu; the third time is in mid-August, applying 30 kg of compound fertilizer per mu. Topdressing should be applied in furrows opened around the root zone of the plants in combination with cultivation and weeding.
(3) Removal of flower buds. When flower buds appear from late July to early August, except for seed plots, remove them all so as to concentrate nutrients for the growth of underground rhizomes, promote their enlargement and thickness, and improve yield and quality.
(4) Drainage. Bupleurum fears waterlogging. In the rainy summer season, attention should be paid to clearing ditches and draining water to avoid root rot.
4. Harvesting. Bupleurum is generally dug up for medicinal use after autumn of the second year after sowing. When the plants wither or before sprouting and seedling emergence the following spring, dig out the underground root strips, shake off the soil, remove the stems and leaves, and after drying in the sun, they can be graded and sold.