Lettuce is a common vegetable, its taste is crisp, delicious, can be fried, cold mix, soup, pickling, etc., in all parts of China are cultivated, adaptability, cold tolerance, like cold and cool climate but not high temperature resistance, like humidity, the need for fertilizer is larger. The following is to tell you about the high-yield cultivation technology of spring lettuce
First, the existing problems
1． Channeling In the middle of growth, the fleshy stem is slender, the leaf internodes are elongated, the leaves are thin and small, the outer skin is thick and the flesh is small, the edible value is not high, and it is easy to smoke and flower, this phenomenon is commonly known as "channeling". There are roughly four reasons for "channeling": one is insufficient water supply and soil drought; the second is insufficient fertilizer supply and poor nutrient growth; third, the temperature is too high, the respiratory intensity is large, the consumption of nutrients is high, and the distribution rate of dry matter to the edible part is low; the fourth is too much watering.
2． In the late stage of the expansion of the fleshy stem of lettuce, the fleshy stem splits longitudinally, reaching deep into the middle of the stem, and the cracked part is yellow-brown, perishable, reducing the edible value. The causes of the cracks: one is related to the variety; the other is related to the uneven supply of water and fertilizer, sudden drought and flooding, especially when the fleshy stem is mature, the outer skin has been lignified, at this time a large amount of watering, the fleshy stem suddenly expands, and the epidermis cannot be expanded with it and the crack.
3． Unripe lettuce Spring lettuce colonizes too late, affected by high temperature and long sunshine, rapidly differentiates flower buds and flowers. In addition, colonized seedlings are too large or long, and they are also prone to the phenomenon of late ripening and extraction.
Second, high-yield technology
In view of the above problems in the cultivation of spring lettuce, we should take necessary high-yield cultivation measures.
1． Variety selection Should choose varieties that are not easy to crack, generally purple leaf lettuce has a large water content, high yield, the most prone to cracking, green leaf lettuce relatively light cracks.
2． Sowing at the right time as early as possible, so that it can fully grow in the root system and leaf clusters at a lower temperature, for the rapid hypertrophy of the fleshy stem to accumulate a large amount of dry matter, my region is generally sown in the greenhouse in early to late February, if sown too late, the flower stem is fertilized, in case of high temperature breathing intensity, easy to "channel".
3． Cultivation of strong seedlings Cultivating 667 square meters (mu) of lettuce requires a seedbed area of 15 square meters, 50 grams of seeds, and the sowing bed soil should be prepared into nutrient soil in advance. The ratio of nutrient soil is: 7 parts of cooked soil that has not been planted, 3 parts of high-quality decomposed organic fertilizer, and add inorganic fertilizer, mix 50 grams of compound fertilizer per cubic meter, mix well, and siev. The nutrient soil is then flattened into the sowing bed, generally 6-7 cm thick, and about 100 kg of vegetative soil is used per square meter.
After the sowing bed is ready, sow the seeds immediately. Before sowing, the seeds should be treated, the seeds should be dried for 2-4 hours, and then soaked in 20 ° C water for 3-4 hours, scrubbed and drained, you can sow seeds, you can also put the soaked seeds in a 15 ° C -20 ° C environment to germinate, after 2-3 days of budding after sowing.
The sowing method generally adopts the sowing method, on the flat bed soil, watering before sowing, after the water seeps down, the seeds or buds are mixed with 4-5 times the volume of the seed moist fine sand, evenly sprinkled into the furrow surface, covered with 0. 5-1 cm thick fine soil, after covering the soil, flat mulch film, is conducive to heat preservation and moisturizing. Under the temperature conditions of 15 °C to 20 °C, when most of the seedlings are top soil for 1-2 days, the mulch film is removed in time.
After sowing, the temperature is controlled at 20 ° C - 25 ° C during the day, about 15 ° C at night, and the seedlings can be planted in 3-5 days. After emergence, the temperature is maintained at 18 °C-20 °C during the day, about 12 °C at night, when the seedlings are 2-3 leaves, the seedlings are divided into seedlings in the cold shed, the seedling spacing is 5-7 cm, and the seedlings are slowly sprayed 1-2 times of foliar micro-fertilizer, and sprayed with Bacteriosus Qing and Tobzin to prevent disease. Water management is based on the principle of keeping the soil moist, not dry and not watered. Too dry or too wet can easily cause seedling aging or growth.
4． Colonization Lettuce root system is developed, the root group is dense, the root system is shallow, the absorption capacity is poor, more organic fertilizer needs to be applied, generally 667 square meters of high-quality organic fertilizer is more than 5000 kg, diammonium phosphate is 50 kg, potassium sulfate is 15 kg, as a bottom fertilizer, and then the land is prepared to make furrows, and the furrow width is 1. 2 meters.
From mid to late April, the seedlings are planted in time when 4-5 true leaves, the row spacing is 40 cm, the plant spacing depends on the variety, generally 25-30 cm, 4 rows per furrow are colonized, and about 6000 seedlings are generally planted in 667 square meters.
The day before colonization, spray the seedbed with water to moisten the soil, and dig the seedlings with as much soil as possible to hurt the roots. Due to the low external temperature at the time of colonization, warm weather with no wind after a cold day should be selected. The planting depth should be buried in the soil, not too deep to press the heart leaf, and the soldier should press it slightly so that the root is fully closely connected with the soil.
5． Field management after colonization After planting, the water-controlled squat seedlings between 2-3 leaf rings promote root development and lotus leaf development, and when the leaves and lotus leaves are synchronized, the stem begins to enlarge, and should be watered and applied with fast-acting nitrogen and potassium fertilizers, and timely from "control" to "promotion". This water and fertilizer must be timely, too early and too late for the growth of fleshy stems. After the start of watering, the fertilizer speed of the stem is accelerated, the demand for water and fertilizer increases, the ground is slightly dry, the watering should be uniform, the amount of water should be moderate, and the flood irrigation should be strictly prevented. When the ground can enter people, the shallow loose soil breaks the plate, combined with watering, and then topdressed 1-2 times, each time per 667 square meters of urea about 20 kg, the amount of fertilizer should not be too large, in order to prevent stem cracks.
6． Disease and pest control Through the cultivation observation in the past two years, the main diseases of lettuce in our area are downy mildew and leaf spot disease, which can be controlled alternately by Bacillus Qing, Daisen manganese zinc and Tobzin, Pulik water agent.
The main pests are aphids, whiteflies, kudzu winter night moth, red spider and so on. Aphids and whitefly are controlled with lice aphids and all souls. Lettuce winter night moth is controlled with enemy insects, enemy killing, Bt emulsion and so on. Red spiders are controlled by double armor squints and exterminations.
7． Harvest at the right time When the top of the main stem of the lettuce and the tip of the highest leaf are usually harvested, the fleshy stem is fully expanded and the quality is crisp and tender. The apical growth points can be removed for phased harvesting to prevent "channeling" seedlings or cavity aging. However, the interval period should not be too long, and when it is found that the lettuce has a slight crack, it should be harvested and listed early, generally 667 square meters of output of 2500-3000 kg.