Cultivation techniques of lettuce in greenhouse before and after Spring Festival

Lettuce

The cold resistance of lettuce decreases when it grows up, and it is vulnerable to frost, so overwintering lettuce should be cultivated in greenhouse, and plastic film mulching can also be cultivated in open field in warm winter area. It is generally sown from mid-late September to early October and listed before and after the Spring Festival, with a yield of 1500kg to 2500kg per mu.

Sow seeds and raise seedlings. Choose late-maturing varieties. The sunshade net is used to cover the ground to cool and moisturize, remove the mulch immediately after emergence, seedling once after the seedling is complete, keep the seedling distance 3-4 cm, properly control watering, and apply 0.3% urea solution once to cultivate strong seedlings.

Planting in the greenhouse. The seedling age of overwintering lettuce was controlled at 30-40 days, with more than 4-5 leaves, and was planted from late October to November. The plant spacing is 33cm to 40cm, and the density of pointed leaf species is higher than that of round leaf species. Before planting, the Kang field should be ploughed for 5-7 days, combined with the application of rotten organic fertilizer. The yield of lettuce was lower when the soil was turned over.

Keep warm and prevent frost. After planting, the greenhouse film will be covered early, but in sunny and warm days, the edge film should be lifted and both ends should be ventilated, and the frost weather with cold wave should be closed to keep warm. After January, there is a lot of rain and rain and snow, so we should pay attention to the heat preservation of the closed shed. At night, we can cover the greenhouse with grass curtains or cover the shed with a small shed to prevent freezing. After the fleshy stem began to expand, the temperature was kept at 18: 20 ℃ during the day and 10 ℃ at night.

Topdressing and watering. After the planting survived, the fertilizer and water management mastered the winter control and spring acceleration, and generally irrigated the fresh manure water for 2 or 3 times before going to the shed, combined with temperature control to prevent overgrowth. One month after planting, heavy fertilizer should be applied, 10 kg of urea, 10 kg of potash or 50 kg of plant ash per mu, and 0.2% potassium dihydrogen phosphate or 2000 kg of rotten manure water should be sprayed on the leaves. Keep the soil moist throughout the growing period, close to controlled watering before harvest.

Regulation of plant growth regulators. In order to control the overgrowth, about half a month after planting, the spray concentration of paclobutrazol was 100 × 150 mg / kg or the concentration of paclobutrazol was 300 mg / kg. If the tender stem still grows fast, or due to market reasons, the listing should be postponed appropriately, and it can be sprayed again after 10-15 days to make the succulent stem grow more sturdy. 15-20 days before the market, the whole plant spray concentration of 20,25 mg / kg gibberellic acid can increase the yield by 10% 20%.