Lettuce is a 1-year-old or 2-year-old vegetable of the Asteraceae family. It is native to the Mediterranean coast and enjoys a cool, humid climate. Lettuce also known as lettuce, according to the edible portion can be divided into leaf lettuce and stem lettuce. Lettuce is lettuce, or lettuce, and is a kind of leafy lettuce. It is called salad vegetables in Western countries and it is mainly used for raw food. It can also be used as a salad dish with crispy texture. In recent years, lettuce has gradually been accepted in the north, and its cultivation area has been expanding year by year.
First, the requirements of environmental conditions
1. Lettuce lettuce with temperature is cold and avoid high-temperature crops. Seeds can germinate above 4°C, and germination temperature should be 15～20°C. Seedlings can tolerate lower temperatures, grow robust at a daily average temperature of 12°C, and the optimal temperature for leaf growth is 13 to 16°C. However, some varieties of lettuce are currently resistant to high temperatures, but they are best harvested in time before the rainy season.
2. Light-enclosed lettuce is a long-day crop and requires sufficient sunlight during growth. Insufficient light can lead to irregular ball or loose ball.
3. Soils Although lettuces are widely adaptable to soil, in order to obtain good leafballs, fertile lettuce or sandy loam soil must be selected. If the soil is thin and organic fertilizers are insufficient, it is easy to cause various physiological diseases. occur.
4. The roots of the water-bearing Lettuce lettuce are shallowly ploughed into the soil, and sufficient water supply is required before the ball-bearing, and the soil is often kept moist. After the ball is put in, lower air humidity is required. If soil moisture is too high or air humidity is high, it can easily cause soft rot.
Second, varieties
In production, heat-resistant and early-maturing varieties are selected, such as the emperor and Jingyou 1. If a large leaf ball is required, an Alpaca mid-maturing variety can be used.
Third, cultivation technology
1. Selection of sowing dates Chinese cabbage lettuce prefers low humidity and cool environment. The autumn planting period is from late September to mid-November. It is also possible to plant seedlings in protected areas in the early spring and plant them from late April to mid-May.
2. Seeding seedlings Immerse the seeds for a few minutes and wrap them with a damp cloth. Pay attention to the ventilation and put them in a temperature of 15 to 20°C to germinate. After 2 to 3 days of germination, the seeds can be sowed. Nutrition cup seedling method with less species, high survival rate of seedlings, seedling strong, and keep the roots intact when planting, fast growth after planting, Baoxin early. The formula of the nutrition cup nursery soil is 6 parts of soil, 3 parts of compost, and 1 part of chaff (or vermiculite), and add a small amount of borax, and mix it into the cup. Each cup broadcast 2 to 3 seeds. Cover a thin layer of soil after sowing, cover the straw, and apply enough moisture. In addition, some areas use plug seedlings, seedlings are also very good results.
3. Seedling management after sowing buds 2 to 3 days can be uncovered straw, exposing the grass is not easy to produce tall seedlings. Summer planting seedlings, take a shade shed, not only can prevent the impact of rain, but also shade. After emergence, water is sprayed every morning and evening. About 2 weeks after sowing, the seedlings were removed and weak seedlings and tall seedlings were removed, and a robust seedling was kept. 15 days after seedling age, thin urea can be applied. General seedlings 25 to 30 days.
4. Site preparation Before planting and fine preparation, apply enough base fertilizer to loosen the soil so that the root system grows and the fibrous roots absorb the fertilizer and water. Early maturing plants were planted in double rows with a row spacing of 35 cm, a plant spacing of 25-30 cm, an acreage of 4000-5000 plants, and moderately mature and late-maturing species were appropriately replanted for full growth. Sorghum can be used for cultivation, spacing 40 cm, spacing 30 to 35 cm, mu 3000 to 3700 plants. After 3 to 4 days after colonization, appropriate watering should be done every morning and evening to increase the survival rate. If you find missing plants, make up your seedlings in time.
5. Field management Lettuce growth is longer, and it must be divided into several top dressings, usually 7 to 10 days topdressing once. After 4 to 6 days after planting, available N fertilizer was applied to promote root and leaf growth. Potassium fertilizer should be added when starting to pack. Before plant closure, heavy fertilizer should be applied. 20 kg of compound fertilizer and 7.5 kg of potassium chloride should be used per acre. A shallow ditch can be applied between the two rows, and the soil can be covered to prevent the fertilizer from contacting the roots. Planting until the start of the heart (rosette period) can be poured or watered to keep the soil moist. In the rosette period, we must strictly control the moisture and avoid the occurrence of diseases. During the ball period, avoid water or plant contact with water, so do not use water or sprinkler irrigation. Water should be controlled 15 days before harvest. The root system of lettuce is shallow and the cultivator should not be too deep so as not to damage the root system. The cultivator should be carried out before the plant is sealed. In the case of growing large-area lettuce in Japan, black-covered plastic film is used to cool and moisturize and prevent fertilizer loss and weed production.
6. Harvested lettuce from the colonization to harvest, early maturing about 55 days, about 65 days of cooked species, late maturing species 75 to 85 days. But it is better to harvest a few days in advance. Harvesting standards, with both hands can be pressed obliquely from both sides of the ball, to feel solid is not loose is appropriate. Water control 15 days before harvest. When harvesting, select closely planted leaves to cut off from the ground, strip the old leaves, leave 3 to 4 outer leaves to protect the leaf, or strip all outer leaves, and use a polystyrene film for single-ball packaging and transfer in time. Refrigerated compartments are shipped for sale, and the suitable temperature for transportation and storage is 1 to 5°C.
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