Lettuce like cool environment, neither cold, nor heat-resistant, for this reason, planting good lettuce, should master the following technical aspects.
A. Lettuce species selection
Planting lettuce should choose cold and heat-resistant, good resistance to species. Such as ball lettuce, glass lettuce, flowering leaf lettuce and Caesar and other varieties are better.
B. Lettuce soil selection
Should choose fertile, rich in organic matter. Strong water and fertilizer retention, good permeability. Easy drainage and irrigation of slightly acidic soil planting.
C. Sowing lettuce seedlings
Sowing seedlings with 1500kg of well-rotted farmyard manure and 20kg of calcium superphosphate per 667m². mix and level after tilling, in order to make the seeds evenly sown.
1. When sowing lettuce seeds
Can be mixed with a small amount of fine sandy soil, after sowing covered with 0.3-0.5 cm thick tide soil. And cover the film moisture, every 667m² cultivation field need seedbed 20-30m². The amount of seed used is 30-40g.
2. Sowing lettuce in the hot season
Seeds must be germinated at low temperature.
3. Its method
First soak in well water for about 6 hours, scrubbed and retrieved and wrapped in wet gauze. Put in 15 ℃ -18 ℃ germination, or hanging in the water well germination. Or put it in the refrigerator at a temperature of about 5°C. After 24 hours, put the seeds in a cool place to keep warm and germinate.
4. Winter and spring
In winter and spring, we should pay attention to the heat preservation of seedbeds in greenhouse or open field, and control the amount of watering to prevent excessive humidity.
5. Summer open field seedling lettuce
Pay attention to cover with shade net and drench 2-3 times a day to keep the soil moist.
6. Lettuce planting
Glass lettuce seedlings about 25 days old, 4-6 true leaves can be planted, plant spacing 14cm x 18cm.
7. Lettuce with balls
The seedlings can be planted when they are 30-35 days old and have 5-6 true leaves. Planting spacing is 17cm*20cm, border width is 0.8m-0.9m.
8. planting base
The organic fertilizer should be 4000-5OOOkg, calcium superphosphate 20kg or compound fertilizer 50kg per 667m². planting with soil to protect the roots, timely watering root water. The planting depth should be such that the heart leaves are not buried.
9. Hot season
The trellis should set up in the morning of the planting day and covered with shade net. Transplant after 4 p.m. For winter and spring cultivation, ground cover can used.
10. Trellis transplanting
Daytime temperature should be controlled at 12 ℃ -22 ℃ is appropriate, the temperature is too low should pay attention to insulation. Temperature above 24 ℃ should uncovered to ventilate and cool down, in general, can make the greenhouse skirt film open.
D. Field management
After the slow water to see the soil moisture quiet and growth situation to grasp the number of watering. Generally 5-7 days watering a water. When the temperature is low in spring, the amount of water should be small and the date of watering interval should be long.
②Lettuce growth period
The soil should kept moist as it needs more water. After the leaf ball is formed, watering should controlled to prevent uneven moisture from cracking the ball and rotting the heart. When the balling starts in protected cultivation, watering should not only ensure the water needs of the plant, but also not too much. Control the humidity in the field should not be too much to prevent the occurrence of diseases.
③Mid-tillage and weeding
After planting and slowing down, weeding should carried out to enhance soil permeability and promote root development.
④Fertilization of lettuce
The main fertilizer is the base fertilizer, when the base fertilizer is sufficient, the first stage of growth can not chase fertilizer. To the beginning of the ball, with water to chase a nitrogen fertilizer to promote leaf growth (if you have automatic irrigation equipment, you can use more efficient and fast water-soluble fertilizer). 15-20 days to chase the second fertilizer, nitrogen, phosphorus and potassium compound fertilizer is better. Use about 15-20 kg per mu, when the heart leaves begin to curl inward. Once again chase to combined fertilizer, with about 20 kg per mu.
There are downy mildew, soft rot, virus disease, dry rot, top burn disease, etc.
leaf miner, whitefly, aphid, thrips, etc. Leaf lettuce is mostly used for raw food, and pests and diseases should prevented.
⑦ Chemical control
Low toxicity, high efficiency and low residual pesticides should used, and stop 15 days before harvesting.
E. Scientific harvesting of lettuce
Harvesting period of loose leaf lettuce is relatively flexible, harvesting specifications are not strictly required, according to market needs. The harvesting of nodular lettuce should be timely, according to the different varieties and different cultivation seasons. Generally, 40-70 days after planting, the leaf ball formation, lightly pressed by hand with a solid feel can harvested.