Lettuce (scientific name: Lactuca sativa L.var. angustanaIrish.), also known as lettuce, is a species of lettuce in the family Asteraceae that forms a variant of the fleshy young stem, an annual herb. The stems are used for lettuce, lettuce, green shoots, and lettuce. Delivery period: 1-4 months. Lettuce originated on the Mediterranean coast and was introduced to China around the fifth century. [1] The aboveground stems are edible, the stem skin is white-green, the stem flesh is crisp and tender, and the young stem is emerald green, which turns white-green when mature. Mainly eat the fleshy young stems, can be eaten raw, cold mixed, fried, dried or pickled, young leaves can also be eaten. The stems and leaves contain lettuce and lettuce (C11H14O4 or C22H36O7). Bitter taste, has an analgesic effect. Lettuce is highly adaptable and can be cultivated in spring and autumn or overwintering, mainly in spring and harvested in summer.
<h1>First, what are the varieties of lettuce</h1>
1. Sharp-leaved lettuce
Characteristics: The plant is tall and large, 1.2-1.8 feet high, the leaves are light green, the shape of the cloak, the page has light wrinkles, a little white powder, and the back of the leaf has more white powder. The shoots are long and stick-shaped, tapering in the upper part, and are about 1.5 feet long. Single bamboo shoots weigh 1.5-2.0 pounds, bamboo shoots skin light white green, meat color slightly darker, bamboo shoot meat dense, tender, crisp, less water content, good quality, can be raw and cooked, can also be pickled. It is cold-tolerant and heat-resistant at the seedling stage, and can produce about 8,000 catties per mu in spring and autumn.
2. Round-leaved lettuce
Characteristics: The height of the plant is about 40 cm, and the degree of development is 25-30 cm. The leaves are erect and oblate, bluntly rounded at the apex, light green, the leaf surface is wrinkled, the stem is 25-30 cm long, the horizontal diameter is 4.5-5 cm, and the stem skin is greenish white and the flesh is white. The fleshy stem of a single plant weighs 250-300 grams, has good quality, the meat is crisp and tender, the aroma is strong, the growth period is 180 days, and it is mainly cultivated in spring.
3. Hanging silk red lettuce
Characteristics: It is a traditional local variety in Sichuan Province. The growth is strong, the plant height is 53 cm, the degree of development is 53 cm, and the leaf clusters are relatively compact. The leaves are inverted ovate, the leaf surface is slightly wrinkled and shiny, the leaf margin is wavy and shallow, the edge of the heart leaf is reddish, and the petiole has purple-red patches at the birth. The stem is oblong-conical, 30 cm long and 5 cm wide. The stem flesh is green and of good quality, and the single stem weighs 600-700 grams, weighing up to 1 kg. Early and medium-ripening, 100-105 days after sowing, the harvest begins. Fertilizer resistant, disease resistant, adaptable. The yield is high, with a yield of 2000-2500 kg per mu.
4. Green-skinned lettuce
Characteristics: newly bred, precocious, heat-resistant, oblong leaves, not easy to chaff heart, moss resistance in general. The leaves are 23-30 cm long, inverted ovate, the leaves are green in color, the fleshy stem is thin, the skin is light and tender greenish white, the taste is fragrant, and the quality is good.
5. Two white-skinned lettuce shoots
Characteristics: Purified species, round leaves, green, greenish white skin, single stem weight 600g, excellent quality, colonization to harvest 11-120 days, yield 2000-2500kg/667 square meters.
6. Fujian Feiqiao purple leaf lettuce
Characteristics: Mostly produced in Linyi, Shandong, Hezhou area, Guangxi District, the leaves are lilac, with fragrant taste, emerald green flesh, good taste and other characteristics.
7. Yong'an lettuce
Characteristics: Affected by specific geographical climate and other growth conditions, Yong'an lettuce has the characteristics of emerald green flesh, crisp and tender, juicy, less fiber, thick stem, thin skin, non-hollow, high edible rate, strong aroma and smell, low nitrite content, unique flavor and excellent quality.
<h1> Second, the annual lettuce planting schedule</h1>
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1. Spring lettuce
Greenhouse nursery time: December to March, open field seedling sowing time: February to March.
2. Summer lettuce
Open-field cultivation time: April to May, shade net shading coverage time: May to July; live broadcast or high-density transplantation.
3. Autumn lettuce
Shade net shade coverage time: July-September; seedling transplanting.
4. Winter lettuce
Open-field nursery time: October to November.
<h1> 3. Seedling time and method</h1>
l. Land preparation
a. Seedbed requirements: land with high terrain and dry and good drainage performance.
b. Pre-sowing treatment: Yifuyuan planting 5-10kg + 1.5-3 tons of decomposing organic fertilizer or 50kg of compound fertilizer as base fertilizer per mu of land.
c. Pre-treatment of land preparation: apply before land preparation and then carry out deep turning, level and fine cover with plastic film for sowing.
2. Seed treatment
Due to the relatively high temperature in May and September, it is difficult for the seeds to germinate, so it is necessary to carry out low-temperature germination before sowing, and the seeds are placed in the nutrient water diluted 200-300 times by the Yifuyuan microbial nutrient solution for 6-7 hours, and then wrapped in wet gauze in the environment of minus 3 or minus 5 degrees The monkeys are frozen for 24 hours, and then placed in a cool place, waiting for two or three days to germinate.
3. Sowing
3.1 Spring lettuce
a. When sowing seedlings in greenhouses, spring lettuce first unveils the plastic film on the seedling furrows, pours the sole water, sprays 3-5kg of Yifuyuan microbial nutrient solution per mu, and then mixes the seeds in a small amount of fine soil and stirs evenly after sowing. Generally speaking, the sowing amount of 10㎡ seedbed is 25-30g, and after sowing, it is covered with 0.3-0.5cm of fine soil and covered with film, and the shade net is covered at night, and if it is open field seedlings, it is covered with a small supply shed.
b. Before the lettuce seedlings are unearthed, the cover cover is uncovered late, no ventilation is required, the temperature of the seedbed is improved, and after the seedlings are unearthed, the shade net is uncovered early and the evening cover is appropriately ventilated, and the daytime temperature is within the range of 12-20 degrees, and the nighttime temperature is within the range of 5-8 degrees. When the seedlings grow to 2-3 straight leaves, the seedlings are interspersed once, the seedling spacing is 5 cm, and the ventilation is increased 5-6 days before transplanting.
3.2 Summer lettuce
a. The best weather for summer lettuce sowing is cloudy, sow wet seed cover film when inquiring in April-May, remove the film after the lettuce emerges, and in May-October, cover the shade net with a small arch or flat shed to lettuce seedlings, or grow to 2 true leaf seedlings once in lettuce, grow to 4-5 true leaves once, the seedling spacing is 10cm, and for the growing and robust lettuce seedlings can be planted according to the plant row distance of 10cm.
b. After each completion of the inter-seedling, room seedling and transplanting slow seedling, it is necessary to combine watering and apply decomposing thin manure water, and in rainy weather, the ditch should be cleared and drained. 15 days before planting, each mu of land is watered once Yifuyuan microbial nutrient solution water 3-5kg, and within 25 days after the seedlings are settled or transplanted, the lettuce young plants can be harvested and listed.
3.3 Autumn nest shoots
a. Before sowing autumn lettuce, the seedbed is first wet with diluted water of Yifuyuan microbial nutrient solution, and after sowing, a layer of 3-4% concentration of decomposed pig manure residue is poured and covered with thin straw (covering black shading net is also OK), and germinated seeds or wet seeds. The double-layered floating surface is covered on the seedbed soil before emergence, and after emergence, it is covered with a silver-gray shade net.
b. Water and fertilizer in the morning and evening, keep the seedbed in a moist state, and also need to weed seedlings.
<h1> Fourth, colonization and management technology</h1>
1. Colonization
When lettuce colonization, it is necessary to choose soil with good drainage performance and apply 4000-5000kg of decomposing organic fertilizer per mu of land. After ploughing the land, make a tall furrow 1.2-1.5m wide. Lettuce seedlings are watered on the seedbed with diluted water of Yifuyuan microbial nutrient solution.
2. Spring lettuce
Wait for lettuce to thrive for 25-30 days, colonize 5 delicate leaves, water after colonization, and apply enough bottom fertilizer for mulching to cover cultivation, and cover the film, and in the rainy season, do a good job of drainage and stain-proofing. For greenhouses and open-field cultivation, it is necessary to plough once or twice in sunny weather, water and fertilize at the right time to keep the furrow surface moist.
Lettuce seedlings are selected for cloudy days or afternoon colonization at 25 o'clock in age, and the distance between colonized plants is 25×35 cm, and watered in time after colonization, and the shade net is covered with a small arch or flat shed. Before and after the capricculation period of lettuce plants, 3000-4000 kg of decomposed human and animal manure are applied per mu of land, or 15 kg of urea is applied two or three times.
4. Overwintering lettuce
Overwintering lettuce seedlings around the daytime using mulch film cover colonization, colonization plant row distance of 30×40cm, after colonization of The application of Yifuyuan microbial nutrient solution diluted water, before wintering should pay attention to refining seedlings, should not be too much fertilizer, to prevent lettuce seedlings from growing too much, in the second year to remove weeds in time, shallow cultivation 1 time, the use of mulch film and greenhouse cultivation, then apply foot fertilizer, pay attention to ventilation management.
<h1> 5. Harvesting</h1>
1. Harvesting of young plants: The stem can be harvested at any time before it is fully enlarged.
2. Lettuce stem harvesting: The highest leaves at the top of lettuce are harvested at the same time.
3, autumn lettuce: can delay harvesting, in the sunny day by hand to pinch the long point and buds, or the lotus stage begins, every 5-7 days spray 350-500 dwarf hormone two or three times.