Cultivation techniques of lettuce

Growing lettuce is a relatively profitable industry at present. On the one hand, there is a large demand for lettuce in the market, on the other hand, lettuce has diversified eating methods and comprehensive nutrition, so it is very suitable for all people to eat. For this reason, the technology of growing lettuce is more important.

Cultivation techniques of lettuce

1. Sowing time: the sowing time of general lettuce is from August to February of the following year, and it is suitable for sowing from mid-October to mid-December, and it can also be sowed in early March and early July, 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. Every 60 square meters, 1500 kg of rotten farm manure and 20 kg of superphosphate were applied to the nursery ground and evenly leveled after ploughing. Seedling transplanting per mu of cultivated field requires a seedbed of 2030 square meters and a seed amount of 25,30g.

2, seed germination: lettuce seeds sowed in high temperature season must be germinated at low temperature, soaked in well water for about 6 hours, scrubbed and then wrapped with wet gauze, placed at 15: 18 ℃, or suspended in a well, or placed in the refrigerator (the temperature is controlled at about 5 ℃), and then put the seeds in a cool place after 24 hours. The seeds can also be soaked in "920" solution with a concentration of 0.2 per thousand for 24 hours, the dormancy of lettuce seeds can be broken smoothly, the seeds can sprout in 2-3 days, and 80% of the seeds should be sowed in time when the seeds are white.

3. Seedling transplanting: pour enough water on the seedling bed before sowing, mix the seeds with the same amount of wet fine sand, then sow them, cover them with about 0.5 cm thick, 2-3 true leaves and time seedlings. Winter and spring greenhouse or open field seedlings should pay attention to seedling bed heat preservation, at the same time should control the amount of water to prevent excessive humidity. Summer open field seedlings, pay attention to cover with sunshade net, sprinkle water 2 or 3 times a day to make the soil moist.

Growth environment of lettuce

1. Temperature. Lettuce likes cold, avoid high temperature, and is slightly resistant to frost. The seeds began to germinate at 4 ℃, and the optimum temperature for germination was 15 ℃-20 ℃, which was inhibited above 30 ℃. The seedlings had strong tolerance to low temperature and could tolerate the low temperature of-3 ℃, and the optimum temperature for seedling growth was 15 ℃-20 ℃, and the optimum temperature for seedling growth was 15 ℃-20 ℃, and it was easy to bolting in advance. The temperature of 16-18 ℃ was the most suitable for leaf bulb growth, and less than 0 ℃ was susceptible to freezing injury. When the temperature was above 25 ℃, the bulbs were loose and the heart leaves were easy to rot. The suitable temperature for flowering and fruiting is 23 ℃-28 ℃. In this range, the higher the temperature, the faster the seeds mature.

2. Moisture. The leaf tissue of lettuce is crisp and tender, the leaf area is large and the water content is high. A uniform and adequate water supply is needed for the whole growth period. However, the requirements for water are different in different periods; the seedling stage should not be too dry or too wet to prevent the seedlings from aging or growing; the rosette leaf should be properly controlled in order to enrich the development of rosette leaves; sufficient water should be required in the heading stage, and the leaves will be small and bitter in lack of water, and if excessive, the leaves will crack or rot.

3. Light. Lettuce is a long sunshine plant, which likes light and avoids shade. In seed production, increasing the hours of light can promote bolting and flowering.

4. Soil and nutrients. The root system of lettuce is well developed, so it is appropriate to choose fertile sandy loam or light clayey loam when planting. Because of the shallow distribution of roots, there is an adequate supply of nutrients on the surface of the soil, and because of its short growth period, the edible parts are leaves, and sufficient nitrogen fertilizer is required, at the same time, appropriate phosphorus and potassium fertilizers should be applied together. The lack of phosphorus in the seedling stage led to dark green leaves and slow growth. When potassium was deficient in the later stage of growth, the leaf bulb was loose and the quality decreased. The rational use of calcium, magnesium, boron and other fertilizers can enhance disease resistance, increase yield and improve quality.

Sowing time of lettuce

Lettuce likes the cold climate, so the sowing time is usually in spring and autumn. Spring usually begins to sow from February to April, and can be harvested from May to June, while autumn sowing can start at the end of August and can be harvested from September to October. Because the characteristics of different varieties of lettuce are different, when choosing the sowing time, you should first know the description of the seeds of lettuce you buy. Then sow seeds in combination with the above sowing time. Spring and summer are suitable for sowing loose leaf lettuce (such as cream lettuce, colored leaf lettuce), more heat-resistant, autumn and winter are suitable for sowing heading lettuce (also known as western lettuce), not heat-resistant.

Disease and pest control of lettuce

The main diseases of lettuce are downy mildew, soft rot, virus disease and Sclerotinia sclerotiorum, among which Sclerotinia sclerotiorum and soft rot are more harmful and are easy to occur in warm and humid conditions. Take rotation, appropriately reduce planting density, not too much watering, often shallow hoe, to keep the soil surface dry. Often clean the field, find diseased plants, pull out in time. Remove dead leaves and concentrate on burning. Agricultural streptomycin and desenamine can be sprayed after the disease. In the season of high temperature and humidity, chlorothalonil is sprayed every 5 to 7 days for preventive purposes. Insect pests are mainly aphids, thrips, ground tigers, etc., with omethoate, quick kill and other control.

The cultivation of lettuce is very similar to that of other vegetables, and generally speaking, the planting steps are more or less the same. However, there are certain differences in the growth characteristics of each kind of vegetables, so growing lettuce needs to be carried out according to the growth habits of lettuce, and must not be blind.