Detailed Explanation of Key Points for High-Yield Evening Primrose Cultivation Techniques
Evening primrose originates from North America, commonly known as mountain sesame and night-blooming evening primrose, belonging to the Onagraceae family, an annual or perennial wild herbaceous plant. It is a perennial herb of the Onagraceae family, often cultivated as a 1- to 2-year-old flower. The plant is upright or ascending, sparsely branched, with coarse long hairs. The lower leaves are linear-oblanceolate, the stem leaves are lanceolate, sessile. Single flowers are axillary in the middle-upper part of the branches, yellow, opening in the evening to night, with a delicate fragrance. The upper part of the fruit often thickens. The flowering period is from July to September. Like the Epiphyllum, it opens at night, hence the name night-blooming evening primrose, with a pleasant fragrance, suitable for embellishing night scenes, and used in combination with other landscaping materials for gardens, courtyards, flower beds and roadside greening. It has strong adaptability, is acid-tolerant and drought-tolerant, and has no strict requirements for soil; it can grow on generally neutral, slightly alkaline or slightly acidic soil, and on well-drained, loose soil. If the soil is too wet, the roots are prone to disease. In the north it is an annual plant, and south of the Huaihe River it is a biennial plant. As an economic crop, the flowers of evening primrose can extract natural fragrance, and it is the main variety of natural fragrance in the north; evening primrose seeds can be sold directly as a commodity, or further processed and refined into evening primrose oil. Evening primrose oil (a fatty oil obtained by extracting and refining the seeds of evening primrose) contains T-linolenic acid and other nutritional components, and has medicinal effects such as lowering blood lipids, resisting arrhythmia, preventing arteriosclerosis and weight loss. It is also widely used in food additives, cosmetics and other food industry and chemical industry fields. The product has high added value and broad prospects in the international market. The soil and climate are suitable for large-scale planting of evening primrose, farmers have enthusiasm for planting, and it is a key characteristic economic crop cultivated in rural areas. Artificial cultivation of evening primrose has a history of nearly 20 years. The high-yield cultivation techniques for evening primrose are briefly introduced below:
1. Selection of Previous Crop and Land Preparation
Evening primrose grows on sunny slopes, grasslands, roadsides and roadside. It likes a warm, humid climate. It also likes light and is cold-resistant. It has no strict requirements for soil, and can grow robustly and develop well on medium-fertility soil. It is suitable for growth in neutral, slightly acidic or slightly alkaline soil. To achieve high yield in artificial cultivation of evening primrose, it is necessary to select suitable soil and previous crop.
1.1 Land selection: It is advisable to choose non-waterlogged, well-moistened, loose-textured, well-aerated, sunny flat land or second-lowland.
1.2 Previous crop selection: Mainly soybean stubble, corn stubble and potato stubble are suitable, and continuous cropping is not allowed. According to the biological characteristics of evening primrose, it is taboo to plant in plots where long-residual herbicides such as imazethapyr, fomesafen and chlorimuron-ethyl were applied to the previous crop.
1.3 Land preparation: Because evening primrose seeds are small and have strict requirements for soil conditions during germination, combined with the growth characteristics and sowing time of evening primrose, land preparation should be done in summer and autumn, leveled and harrowed fine, and the topsoil should be clean.
2. Seed Selection and Treatment
2.1 Variety selection: Select excellent annual varieties with robust growth, early flowering, large pods and good yielding ability.
2.2 Seed treatment: Soak the seeds in 250 times liquid of 70% thiophanate-methyl for 15-20 minutes for chemical seed soaking. After removing, soak the disinfected seeds in 30°C warm water for 24 hours. Remove the seeds, drain the water, and sow once the seeds are shade-dried and no longer stick to each other.
3. Timely Sowing
3.1 Autumn sowing: In Northeast China, the best sowing time is autumn sowing. Because autumn soil moisture is good, seeds absorb water well, seedlings emerge early in spring, and the seedling survival rate is high. The autumn sowing time in our county is late October.
3.2 Spring sowing: Spring sowing must be early. Sow when the soil thaws 3-5 cm in spring. Only with good soil moisture can full seedlings be ensured. The spring sowing time is early April.
4. Sowing Methods
4.1 Mechanical sowing: Replace the sowing plate of the precision seeder with a millet sowing plate, adjust the sowing rate with small holes for precision sowing, use 7.5 kg of seed per hectare, sow at a depth of 1 cm, cover with 0.5 cm of soil, and compact after sowing to maintain good soil moisture.
4.2 Manual sowing: Open a 10 cm wide, 1 cm deep furrow on the ridge, first tread the bottom of the furrow firmly and evenly, then sow the seeds evenly in the furrow by dribbling gourd or by hand, cover with 0.5 cm of soil, and tread the furrow repeatedly on top, or compact appropriately with a roller to maintain good soil moisture. This is the key link for full seedling emergence. Use 6-7.5 kg of seed per hectare.
5. Fertilization
Mainly use farmyard manure. Combined with land preparation, apply 30-45 m3 of high-quality farmyard manure per hectare. For thin soil plots, apply 37.5-75 kg of diammonium phosphate per hectare combined with land preparation, and apply 37.5 kg of urea per hectare as topdressing at the early bud stage.
6. Field Management
6.1 Field inspection and reseeding: Inspect the field promptly after evening primrose emerges. If missing seedlings or broken rows are found, reseed after sprouting, or transplant seedlings with water to fill gaps, so that the field seedling survival rate reaches 80%.
6.2 Thinning and final singling: Thin seedlings at the 2-3 leaf stage, keep a plant spacing of 10-12 cm, and thin into double-row staggered seedlings, with 250,000-300,000 plants per hectare. Replenish seedlings promptly in plots with missing seedlings.
6.3 Cultivation and weeding: Evening primrose is a wild plant, and after artificial cultivation it must be carefully managed, with two hoeings and three cultivations, and no weeds in the field.
6.4 Control of main diseases and insect pests of evening primrose
6.4.1 To control fusarium wilt, if diseased plants are found in the field, pull them out, turn over the soil around the plant and spread quicklime for disinfection, then replant after 30 days. For chemical control, use 600-800 times liquid of Kusuilike or 50% carbendazim.
6.4.2 To control root rot, when there is excessive rain, rot disease is likely to occur. The roots of diseased plants gradually discolor and rot, and the leaves wilt and dry up, causing the whole plant to die. While strengthening cultivation, irrigate with 1500 times liquid of 50% thiophanate-methyl.
6.4.3 To control mites, spray the leaf surface in the field with 2000 times liquid of 73% propargite;
6.4.4 To control aphids and scale insects, use 40% dimethoate emulsion or 2.5% deltamethrin or 10% cypermethrin or pymetrozine 10-15 g per mu mixed with water and sprayed on the leaf surface.
7. Harvest
7.1 Timely harvest: Evening primrose is a plant with indeterminate flowering and pod-setting, so the harvest period cannot be determined by the maturity of the whole plant; harvest at the proper time. The harvest standard is when the pods at the bottom of the stem crack for 3-5 hours, then it can be cut, generally from September 20 to September 30. After cutting, tie into bundles, stand them in the field for after-ripening for a general period, then thresh.
7.2 Threshing: When threshing, it should be done on a cement floor or with a tarpaulin, plastic sheet, etc. laid underneath to avoid mixing in impurities. Seeds with high moisture content should be dried promptly to prevent mold.