[Edit this paragraph] Overview
Lettuce is a common name for leaf lettuce and belongs to the genus Lettuce in Compositae. As an annual or biennial herb crop, it is also a popular vegetable in Europe and America and is deeply loved by people. Lettuce is native to the Mediterranean coast of Europe and domesticated from wild varieties. The ancient Greeks and Romans ate it first. Lettuce has been introduced into China for a long time, and has been widely cultivated in the southeast coast, especially in the suburbs of big cities and Guangdong and Guangxi regions, especially in Taiwan Province Province. In recent years, the planting area has expanded rapidly, and lettuce has also entered the dining table of ordinary people from hotels and restaurants.
[Edit this paragraph] Features
Lettuce can be divided into green lettuce and purple lettuce according to the color of leaves. According to the growth state of leaves, there are two kinds of lettuce: loose leaf lettuce and bulbous lettuce. The leaves of the former are scattered, while those of the latter are spherical. If subdivided, there are three kinds of lettuce. One is buttered lettuce, with inverted oval leaves, smooth leaves, soft texture and slightly corrugated leaves; Another kind of crisp lettuce has obovate leaves, shriveled leaves, crisp texture and serrated leaves. The latter culture is more common; There is also a kind of bitter leaf lettuce, which has thick, oval, full and hemispherical leaves and is rarely cultivated.
Head lettuce has a cool climate, and the suitable growth temperature is 15-20℃, which is most suitable for the environment with large temperature difference between day and night and low temperature at night. The optimum temperature for nodulation is10-16℃. When the temperature exceeds 25℃, the heart leaves will be necrotic and rotten due to the high temperature inside the lobe ball, and the growth will be poor. Seed germination temperature is 15-20℃, higher than 25℃. Because the seed coat is blocked from absorbing water, the germination is poor. Lettuce should be treated at low temperature when sowing in summer. After soaking, it should be placed in the refrigerator to accelerate germination, and then sowing should be carried out after the buds turn white. Loose-leaf lettuce is more heat-tolerant, but it does not grow well in high temperature season. The soil with slightly acidic lettuce (pH 6-6.3 is the best) is cultivated in sandy loam or clay loam with strong water holding capacity and good drainage. Lettuce needs more nitrogen fertilizer, and organic fertilizer should be applied to the base fertilizer before planting, and no organic fertilizer should be applied during growth. Water shortage is not allowed during the growing period, especially at the heading stage of lettuce, which requires sufficient water. If there is water shortage in advance, not only the leaves will be small, but also the leaves will be bitter and of poor quality. But the water should not be too much, otherwise the bulb will crack, which will affect the appearance quality and easily lead to soft rot and Sclerotinia sclerotiorum Only proper water and fertilizer management can obtain high-yield and high-quality lettuce.
[Edit this paragraph] Practice point
Lettuce is a cold vegetable, which is cultivated in the open field mainly in spring and autumn. If it is to be supplied all year round, it should be produced in combination with open field and protected land, which can basically meet the annual demand. In Shanghai, when cultivated in spring, seedlings are usually raised in cold beds from the end of June to the beginning of February, and planted around the beginning of March. If the seedlings are raised in the open field in spring, they should be sown in early March and early April. The row spacing is generally 30 cm square, and 5000-6000 plants are planted every 666.7 square meters. Lettuce seeds are small. Generally, 666.7 square meters can be planted by sowing 25 grams. Depending on the maturity of the variety, it takes 30-50 days from planting to harvesting. Autumn cultivation is often carried out in August. When sowing in hot season in Shanghai, the seeds must be soaked for 3-4 hours to fully absorb water, then wrapped in cloth and put into the freezer to accelerate germination. The temperature is generally controlled within the range of 5- 10℃. After 4-5 days, 70-80% can be sown when white buds are exposed. After sowing, fully water the seedbed and cover it with wheat straw. If there is a sunshade net, it is more ideal to build a shed for sunshade. When 60%-70% of the seedlings are unearthed, the wheat straw must be uncovered in time, but shade is still needed to prevent the seedlings from dying at high temperature. Sowing in autumn, because of the high temperature and large evaporation, the soil must be kept moist throughout the seedling stage, otherwise the seedling emergence is not ideal. Lettuce grows fast and has a short growth period. Some varieties can be harvested more than a month after planting. The single plant weight of loose-leaf lettuce is 250-500g, and the growth period of head lettuce is longer than that of loose-leaf lettuce, generally 400-750g, and the late-maturing variety with long growth period can reach more than1000g. The yield of 666.7 square meters of lettuce varies with varieties, generally 1000-3000 kg.
[Edit this paragraph] Nutrition and consumption
nutrition
1. Lettuce is rich in water, and the water content per 100g edible part is as high as 94%-96%, so it is crisp and fresh when eaten raw. Every 100g edible part also contains protein 1- 1.4g, carbohydrate 1.8-3.2g, vitamin C 10- 15mg and some minerals.
2. Lettuce contains more dietary fiber and vitamin C than cabbage, which can eliminate excess fat, so it is also called slimming lettuce. 3. Because its stems and leaves contain lettuce, it tastes slightly bitter, and has the effects of analgesia and hypnosis, lowering cholesterol and adjuvant treatment of neurasthenia. 4. Lettuce contains active ingredients such as mannitol, which has diuretic and blood circulation promoting effects. Lettuce contains an "interferon inducer", which can stimulate human normal cells to produce interferon, thus producing an "antiviral protein" to inhibit the virus.
Edible method
Lettuce is eaten raw, which is the main course of western vegetable salad. Wash lettuce leaves in cold dishes, with other brightly colored vegetables or meat and seafood, is a salad with good color and fragrance. Wrapping steak, pork chops or fried rice with lard with leaves is also a widely used way to eat. In addition, meat, poultry and other meat-based thick soup, put lettuce on the table and boil it immediately, which is also an excellent soup. In short, there are many ways to eat lettuce, and you can cook it according to your own taste.
Food compatibility: don't eat yam and kansui together. Nor should it be taken with alkaline drugs.
[Edit this paragraph] Recommended recipes
Braised lettuce bag with eel grains
[Ingredients] Fresh lettuce150g, eel back 250g, water-soaked mushrooms 25g, winter bamboo shoots 25g, carrots 25g, green beans10g, garlic 2 petals, ginger 3g and onion 3g.
[Seasoning] Vegetable oil, yellow wine, refined salt, sugar, oyster sauce, pepper, sesame oil and monosodium glutamate.
[method]
(1) Wash the lettuce, shower it with cold boiled water, drain the water and put it into the pot.
(2) washing and draining the back of the eel, and cutting into fine particles; Cut mushrooms, carrots and bamboo shoots cooked in light salt water into diced meat; Blanch the green beans in boiling water, and then take a cold bath for later use.
(3) Add 50 grams of vegetable oil to the pot, cook until it is 60% hot, then add minced garlic, Jiang Mo and chopped green onion, then add eel back grains and stir-fry until the meat is slightly hard, add diced mushrooms and stir-fry, add rice wine, add diced bamboo shoots, diced carrots, salt, sugar, oyster sauce and a little water, simmer for about 3 minutes, and pour in green beans. Sprinkle pepper on the vegetable noodles and serve them, followed by lettuce pots. When eating, take raw lettuce leaves, scoop up a little diced eel and wrap it up to eat.
[Features] Lettuce is crispy and eel meat is delicious.
[Edit this paragraph] Cooking instructions
1. Because there may be pesticide and fertilizer residues, be sure to wash them before eating them raw;
2. It is extremely sensitive to ethylene and should be stored away from apples, pears and bananas to avoid brown spots;
3. Whether it is fried lettuce or boiled lettuce, the time should not be too long, so as to maintain the crisp taste of lettuce;
4. Lettuce torn into pieces by hand will be more brittle than a knife;
5. Wash lettuce, add appropriate amount of salad dressing and eat directly. A regular diet can help women stay slim.
Lettuce in Korean cuisine
Korean is the first ethnic group in East Asia to use lettuce in large quantities. Among them, the most widely known is that in Korean barbecue, eating barbecue with lettuce wrapped in sauce can not only alleviate the greasy taste, but also add fresh and sweet taste and supplement vitamins.
This way of eating has become popular at least in the late Koryo era.