Detailed Explanation of Cultivation Techniques and Planting Key Points for the Medicinal Herb Oenothera biennis
Oenothera biennis, commonly known as mountain sesame and evening primrose, belongs to the Onagraceae family and is an annual or perennial wild herbaceous plant. Oenothera biennis seed oil is rich in linolenic acid and has the functions of lowering blood lipids, strengthening tendons and bones, and dispelling wind-dampness. The medicines prepared from it can mainly treat coronary heart disease, hypertension, arteriosclerosis, obesity, rheumatoid arthritis, dermatitis, muscle and bone pain, and other diseases. Its flowers can be used to extract natural fragrance and are the main variety of natural fragrance in the north. The stem fiber is a raw material for papermaking. The leaves and oil residue are good feed. More than 30 countries have researched and developed Oenothera biennis seed oil, specialized companies already produce and distribute Oenothera biennis oil products, and more than 30 companies have applied for patents for new products such as medicines, foods, and cosmetics with Oenothera biennis oil as the main ingredient. Japan has set off a craze for consuming Oenothera biennis oil products.
I. Growth Habits
Oenothera biennis grows on sunny hillsides, grasslands, roadsides, and roadside edges. It prefers a warm, humid climate. It likes light and is cold-tolerant. It has low requirements for soil, and can grow robustly and develop well in soil of medium fertility. It is suitable for growth in neutral, slightly acidic, or slightly alkaline soil.
II. Propagation Methods
(1) Site selection and land preparation: Choose well-drained, deep, loose, sunny sandy loam soil as suitable. Before sowing, plow deeply 20—25 cm, apply 1500 kg—2000 kg of base fertilizer per 667 sq m, then harrow finely again the following spring, and make 60 cm ridges.
(2) Sowing: Select excellent 1-year-old varieties, divided into autumn sowing and spring sowing. For autumn sowing, sow before the ground freezes, in mid-October and late October. For spring sowing, in early April and mid-April. After the soil thaws, sow as early as possible. Seed treatment before sowing: soak the seeds in cold water for 24—48 hours, then remove and dry in the shade before sowing.
Sowing method: Open a 10 cm wide, 1 cm wide furrow on the ridge, first tread the bottom path, and tread it firm and level. Then evenly drill the seeds in rows into the ridge furrow, immediately cover with soil at a thickness of 0.5 cm, and then tread the upper path well. Sow 500 g of seeds per 667 sq m (1 mu).
III. Field Management
(1) Intertillage and weeding: Oenothera biennis grows slowly at the seedling stage, so weeds in the seedling holes should be pulled out early, and intertillage and weeding should be done promptly after 4—5 leaves have unfolded. First hoe the weeds on both sides, then pull out the weeds in the furrows. Intertillage and weeding need to be combined with shallow cultivation and earthing up 3—4 times.
(2) Thinning and final thinning: When the seedlings are 4—5 cm high, thin out dense and weak seedlings. When the seedlings are 10 cm high, final thinning can be done, with a plant spacing of 20—30 cm, keeping 3300—4000 plants per 667 sq m.
(3) Topdressing: At the early bud stage, 10 kg of diammonium phosphate can be applied as topdressing per 667 sq m.
IV. Pest and Disease Control
Oenothera biennis has strong resistance to diseases and pests, but excessive rain can easily cause rot disease. The roots of diseased plants gradually change color and rot, and the leaves wilt and dry up, causing the whole plant to die. It can be irrigated with a 1500-fold solution of 50% thiophanate-methyl.
V. Harvesting and Processing
Oenothera biennis is used as medicine through its seeds. When half of the seeds have matured, it can be harvested. Pull up the whole plant, tie it into small bundles, dry it in the sun, and then thresh out the seeds. Use different types of screens to remove impurities and soil. After careful selection, store for later use. Each 667 sq m can yield 100 kg.