How to grow lettuce scientifically?

How to grow lettuce scientifically? Please give a detailed description of the planting methods for lettuce cultivation can refer to the following methods: 1. The soil should be planted in slightly acidic soil with fertile, rich organic matter, strong water and fertility conservation, good air permeability and convenient drainage and irrigation. 2. The varieties of lettuce are better than those of glass lettuce, heading lettuce, mosaic lettuce and Caesar. 3. The sowing time of sowing seedlings is generally from August to February of the following year, but the most suitable sowing time is from late October to mid-December. It can also be sown from early March to early May, but the growth period is short and the yield is low. It was cultivated in greenhouse or small shed in winter and early spring, and in sunshade net or shade shed in summer. The nursery land was fertilized with rotten farm manure 1500kg and calcium superphosphate 20kg per 667m2, and mixed evenly after ploughing. Glass lettuce should be sown from September to January of the following year, while heading lettuce should be sown from October to December. For seedling raising and transplanting, the nursery bed 20~30m2 is needed for each 667m2 cultivation field, and the seed amount is 25g / 30g. When sowing in high temperature season, the seeds must be accelerated by low temperature. The methods are as follows: soaking in well water for about 6 hours (hours), scrubbing and picking up, wrapping them with wet gauze, accelerating germination under 15 ℃ ~ 18 ℃, or hanging in wells, or putting them in the refrigerator (the temperature is controlled at about 5 ℃). After 24 hours, the seeds are placed in a cool place to keep warm and accelerate germination. The seeds can also be soaked in "92 ○" solution with a concentration of 2 ‰ for 24 hours (hours), the dormancy of lettuce seeds can be broken smoothly, the seeds can sprout in 2 days (days), and 80% of the seeds should be sowed in time when the seeds are white. Before sowing, the seedling bed should be watered enough, the seeds should be evenly mixed with the same amount of wet fine sand and then sowed, the thickness of the soil should be about 0.5cm, 2-3 true leaves and time seedlings or seedlings. Seedlings raised in greenhouse or open field in winter and spring should pay attention to the heat preservation of seedling bed, at the same time, the amount of watering should be controlled to prevent excessive humidity; in summer, seedlings in open field should be covered with sunshade net and drenched 2 or 3 times a day to keep the soil moist. 4. The seedling age of glass lettuce is about 25 days (days). It can be planted with 4 or 6 true leaves, and the row spacing is 14cm × 18cm. The seedling age of "heading lettuce" was 30-35 days (days), and it was planted with 5-6 true leaves, the row spacing was 17cm × 20cm, and the border width was 0.8m~0.9m. Organic fertilizer 4000~5000kg, superphosphate 20kg or compound fertilizer 50kg were applied per 667m2. Soil should be taken to protect the root when planting, and the root water should be watered in time. The planting depth is appropriate not to bury the heart leaves. If it is planted in the high temperature season, the scaffolding should be built in the morning of the same day, covering the sunshade net, and transplant after 4 pm. Cultivation in winter and spring can be covered with plastic film. When transplanting in greenhouse, the daytime temperature should be controlled at 12 ℃ ~ 22 ℃. When the temperature is too low, attention should be paid to heat preservation. When the temperature is higher than 24 ℃, the film should be ventilated and cooled. In general, the greenhouse skirt can be opened. 5. Field management lettuce needs more fertilizer, so it should be applied frequently and more fertilized. a small amount of available nitrogen fertilizer should be applied 5 days after planting, and after 15 days, each 667m2 should be topdressing compound fertilizer 10~15kg, but human feces and urine should not be used as topdressing fertilizer in the middle and later stage. There is a large amount of water demand after planting, so it should be watered at the right time according to the weather and soil moisture after slow seedling, generally once every 5 to 7 days (days), and not excessive watering in the middle and later stages. 6. Diseases and insect pests control aphids mostly in autumn, winter and spring. Spray control can be done with 40% dimethoate emulsion 600-800 times, or 50% avoiding aphids 2000-3000 times. Sclerotinia sclerotiorum mostly occurs in February to March, and can be sprayed with 70% thiophanate methyl wettable powder 500 × 700 times or 50% paracetamol powder 1000 / 1500 times. Soft rot is easy to occur in high temperature and rainy season. It can be sprayed with 47% Jiarinong wettable powder 1000 times or 77% Jiaoda wettable powder, and the drug can be stopped 15 days before harvest. Click for more lettuce planting techniques click to get more vegetable planting techniques