How to grow lettuce seeds?

Lettuce is native to the Euro-Mediterranean coast, domesticated from wild species, and has a long history of being introduced into China. There are many cultivation in the southeast coast, especially in the suburbs of big cities and in Guangdong and Guangdong, with high planting value. Common cultivated varieties are glass lettuce, emperor, Caesar, heading lettuce, lettuce, big lake 659 and so on. Let's take a look at how lettuce seeds are planted.

Growth habits of lettuce

Lettuce likes cold environment and is neither cold-resistant nor heat-resistant. The suitable temperature for growth is 15-20 ℃, and the growth period is 90-100 days. The seeds were tolerant to low temperature and could germinate at 4 ℃. The optimum temperature for germination was 18-22 ℃, and almost no germination was found when the temperature was higher than 30 ℃. During the growth period, I like the cool climate, and 15-20 ℃ is the most suitable for growth, with high yield and good quality. The growth is poor when the temperature is higher than 25 ℃, but the cold tolerance is also strong. 0 ℃ or even short-term sub-zero low temperature does not hinder the growth. The root system is developed, the leaves are waxy, and the drought tolerance is quite strong, but cultivated on fertile and humid soil, the yield is high, the quality is good, and the soil pH value is 5.8-6.6.

How do you plant lettuce seeds?

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.

Planting management of lettuce

1. Scientific fertilization: lettuce requires clayey loam rich in organic matter and strong water and fertility conservation, lettuce likes slightly acidic, and the soil pH value is 5-7. For every 1000 kg of lettuce, it is necessary to absorb 2.5kg of nitrogen, 1.2kg of phosphorus and 4.5kg of potassium, among which heading lettuce needs more potassium. Nitrogen, phosphorus and potassium fertilizers should be used together during the growing period. The land where lettuce is planted should be ploughed deeply and carefully. Before planting, sufficient basic fertilizer should be applied, and 3000-3500 kg per mu of rotten farm manure should be applied. Turn deeply after application, pour enough bottom water, and make the border after seeing it dry.

2. Careful planting: the seedling bed was irrigated one day before planting to make the seedling moist, and the seedlings started the next day with as much soil as possible to reduce root damage. When planting, first open the ditch on the border surface, the ditch depth is 4cm 6 cm, plant 3 rows on the border surface 70 cm, apply the ternary compound fertilizer according to 25 kg per mu, then irrigate, put the seedlings to cultivate the soil and seal the ditch according to the plant distance of 24 cm, rake the border surface, cover the plastic film, and introduce the seedling out of the film.

3. Post-planting management: lettuce likes to be wet, and sufficient water supply is required during the whole growth period. Slow seedling water was irrigated once after planting for 5-7 days. After watering the seedlings, the plots without plastic film were ploughed and loosened for two times to weed. After watering 3-4 times, combined with watering, nitrogen and phosphorus fertilizer was applied by stages, 15-20 kg per mu. Stop watering before harvest to facilitate storage and transportation.

4. pest control: 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, so rotation can be adopted, planting density should be reduced appropriately, watering should not be too much, shallow hoe should be often done, soil surface should be kept dry, diseased plants should be pulled out in time, withered leaves can be removed and burned, agricultural streptomycin and benzoammonium can be sprayed after the disease. Spray chlorothalonil every 5 to 7 days in high temperature and humidity season for preventive purposes. Insect pests are mainly aphids, thrips, ground tigers, etc., with omethoate, quick kill and other control.