(Zhang Wenhua)

Evening primrose (Oenothera biennis L.) is also known as mountain sesame, to be sky grass, nightshade. For the willowherb family annual or biennial herbs. Native to the countries of North and South America, introduced into Europe, successively spread around the world. China is mainly distributed in Jilin, Heilongjiang and Liaoning provinces, mostly wild. Hebei, Shandong, Jiangsu and other places have a small amount of planting, for ornamental purposes. The seeds are used as medicine. Seed oil content of 20%, the oil contains palmitic acid 5.4%, stearic acid 1.6%, oleic acid 10.4%, linoleic acid 75.5%, linolenic acid 6.8%, and its content and foreign reports of 6-9% of the basic consistency. γ-linolenic acid is a kind of easy to be absorbed by the human body of unsaturated fatty acids, the human body can not be synthesized by the dietary supplement. According to clinical observation, γ-linolenic acid in the human body can regulate the blood lipid-like substances, to reduce cholesterol and atherosclerosis has a significant effect. In addition, it can also treat a variety of sclerosis, obesity, rheumatoid arthritis and schizophrenia, and can inhibit the growth of cancer cells. Evening primrose is a medicinal plant with many uses. The seed oil is used not only as a medicine but also as a nutritional supplement and an ointment for refined cosmetics. The flowers can be extracted as aromatic oils and infusions.

I. Morphological Characteristics

The plant is 1.5-2m tall, with terete roots and erect, branched stems. Seedling stage is rosette-shaped, the base has red long hairs. Leaves alternate, lower stem leaves stalked, upper leaves subsessile; leaf blade oblong, lanceolate, 6-9cm long, 1.5-3cm wide, margin sparsely serrulate, both surfaces white pilose. Flowers solitary in leaf axils at branch ends, arranged in sparse spikes, calyx tube slender, apex 4-lobed, lobes reflexed; petals 4, yellow, stamens 8, 4 opposite petals.

Pistil 1, stigma 4-lobed. Capsule cylindrical, apex pointed, covered with white long hairs, naturally dehiscent at maturity. Seeds small, brownish, irregularly trigonous (Figs. 15-16).

Figure 15-16 Morphology of evening primrose

1. Plant morphology 2. Fruit 3. Stigma 4. Stamens

II. Biological characteristics

Evening primrose is distributed in the sunny mountain slopes, barren land, the edge of the secondary forests, roadsides, riverbanks, and the gap between the open space in front of and behind the house. Strong adaptability, acid-resistant and drought-resistant, the soil requirements are not strict, generally neutral, slightly alkaline or slightly acidic soil, well-drained, loose soil can grow, the soil is too wet, the roots are susceptible to disease. North for annual plants, south of the Huaihe River for biennial plants. Jilin is generally sown in April, began to flower in early July, and the fruit began to mature in mid-August. Hangzhou area in late February to early March sowing, began to emerge in late March, late May pregnant buds, began to bloom in mid- to late June, in August, the fruit began to mature in the middle. Fruiting period is long, seeds can be sown after harvest, no dormant period. Seedlings can safely overwinter in the open ground.

Seed germination without strict temperature requirements. Hangzhou area in the fall when the temperature is about 20 ℃ can be seedling growth, the following spring in late February sowing, the average temperature in early and mid-March 8-15 ℃ can also be germinated, seedling growth. In the nutrient growth and reproductive growth stage, coinciding with the high temperature season in Hangzhou area, the average temperature in July and August between 28-30 ℃, the absolute high temperature at 37 ℃ can also be vigorous growth, flowering and fruiting.

Three, cultivation techniques

(a) varieties and types

Evening primrose species are more, the whole genus *** more than 200 species, the current distribution of the domestic distribution in addition to this species, there are to be sky grass (O. odorata Jacq) and red calyx moon under the incense (O. erythrosepala Borb.) and Lamarck evening primrose (O. larmarkiana Ser). larmarkiana Ser).

(2) Selection of land and land preparation

Before sowing, select loose, well-drained land, deep turning, sunshine for 15-20 days, and then broken up and raked flat, made into 1.5m wide beds. In the deep turning before the application of circle fertilizer or stable fertilizer, cake fertilizer, etc. as a base fertilizer, and then sowing or transplanting seedlings planting.

(C) propagation methods

Evening primrose with seed propagation, northern spring sowing, south of the Huaihe River, autumn or spring sowing seedlings. After the seeds are sown, the soil should be kept moist so that the seeds can absorb water and sprout. About 10-15 days after sowing, the seeds can sprout and grow seedlings. When sowing, the soil should be fine and flat, the seeds are scattered on the bed, gently raked with a rake, covered with a thin layer of soil, the seeds are small, the soil can not be covered with thick, otherwise it will affect the seed germination and growth.

(D) field management

Seedlings in the second pair of true leaves before the extension and weed seedlings are very similar, easy to confuse, this time can not be plowed weed, only in the second pair of true leaves after the unfolding can be carried out. When it grows into a rosette of seedlings, it can be interplanted and fixed or transplanted. The plant spacing is 65×65cm, and when the plant is as high as 30cm, the soil is cultivated around the plant to prevent the plant from falling down. After transplanting or setting seedlings, a manure or urea fertilizer, to promote seedling growth, the first bud when the second fertilizer, in order to facilitate flowering and fruiting.

Evening primrose generally does not need irrigation, if the summer continuous drought, then watering, but the later stages of growth, especially pregnant buds, flowering period, the soil should not be too wet.

(E) pests and diseases and their control

1. Rot disease

(Erwinia sp.)

After the disease, the roots of the plant gradually become discolored and rot, and the leaves wilt and dry, and then cause the whole plant to die. Prevention and control methods: 1% lime water, or 50% Tolbutrazine 1500 times liquid, can also be used 75% Chlorothalonil 1000 times liquid watering.

2. Anomola corpulenta Motschulsky

Larvae damage seedlings. Adults damage petals during the flowering period. Control: see Ginseng.

Four, harvesting and processing

Evening primrose for infinite inflorescences, fruit ripening one after another, generally half of the inflorescence on the ripe can be harvested, late, early ripening of the fruit cracked, the seeds scattered by themselves. Harvesting, with branch scissors or knife to cut the inflorescence (cut), or the whole plant pulled up, spread in the sun to dry, with a mill or stick pressure, to remove all the hulls and impurities, put in a dry cool place for storage. Seeds should not be stored for a long time, a year later, will lose germination power.