Knowledge of cultivation techniques for growing lettuce outdoors in shed

Growers with greenhouses can cultivate leafy vegetables such as lettuce in the outer space of the greenhouse, so as to make full use of land resources and improve economic benefits. Lettuce, also known as leaf lettuce, lettuce, golden lettuce and so on, should get its name from raw food. It is an annual herb that can form leaf balls or tender leaves for feeding in the genus Lactuca of Compositae. The leaves and bulbs of lettuce are crisp, tender and sweet, with good flavor and rich nutrition. 1. Soil preparation, fertilization and ridging. Mu of rotten farm manure 4000-5000 kg, urea 15 kg, phosphate fertilizer 25 kg, diammonium 30 kg, combined with ploughing and ridge application under the ridge, ridge width 50 cm, groove width 40 cm, ridge height 15-20 cm. 2. Planting. When the seedlings were 25-35 days old and had three to four true leaves, the seedlings were watered one day before planting, and the next day the seedlings were transplanted into the field with two rows per ridge. The row spacing of heading lettuce was 20 cm × 30 cm and that of non-heading lettuce was 20 cm × 25 cm. The depth of planting seedlings should not be planted deeply, grasp the soil surface of the seedling tuo and the ground slightly lower for the degree, and then pour stable seedling water (or irrigation after planting). 3. Field management, topdressing and irrigation. Immediately after planting, apply the first fertilizer 5-7 days after planting, apply 10 kg urea per mu, and then water the second time; 15-20 days after planting, in order to promote the formation of rosette leaves, topdressing the second fertilizer, nitrogen, phosphorus and potassium compound fertilizer 15-20 kg per mu, and then irrigate the third water. After 30 days of planting, in order to promote tight heading and large leaf ball, the third topdressing was carried out, and 10-15 kg per mu of compound fertilizer was still applied, and then watered for the fourth time. Ploughing and weeding. After planting and watering for 2-3 times, it is suitable for mid-ploughing, and after re-watering, if the ridge is not closed, it should be ploughed for the second time. 4. Disease and pest control virus disease: virus disease is a common disease of lettuce, widely distributed, serious harm caused by open field planting, the incidence rate can reach 60%, or even higher. Control measures: ① selected disease-resistant and heat-resistant varieties, and general loose-leaf varieties were more resistant than heading varieties. ② timely control aphids, reduce transmission, control disease development, spray 50% aldicarb 2000-3000 times, or once net wettable powder (10% imidacloprid) 1500-2000 times. At the initial stage of the onset of ③, 20% virus A wettable powder was sprayed with 500x solution or antiviral agent No. 1 water agent 300x, once every 10 days or so, even for 3-4 times, and stop spraying 10-15 days before harvest.