Greenhouse Lettuce Seedling Raising Methods and Technical Key Points
How do you raise lettuce seedlings in a greenhouse? Please give guidance. Greenhouse lettuce seedling raising can be carried out by referring to the following methods: ① Variety selection: choose varieties with strong cold tolerance, disease resistance and strong adaptability, such as Emperor, Salinas, Great Lakes 659, etc. The seedbed should be fertile sandy loam with strong water and fertilizer retention capacity. ② Seedbed prepar...
How do you raise lettuce seedlings in a greenhouse? Please give guidance.
Greenhouse lettuce seedling raising can be carried out by referring to the following methods:
① Variety selection: choose varieties with strong cold tolerance, disease resistance and strong adaptability, such as Emperor, Salinas, Great Lakes 659, etc. The seedbed should be fertile sandy loam with strong water and fertilizer retention capacity.
② Seedbed preparation: because lettuce seeds are small, seedbed cultivation requirements are strict, the land must be prepared finely, and the seedbed soil must be fine, crumbly and level. For every 10 sq m of seedbed, apply 10 kg of fully decomposed fine farmyard manure, 0.3 kg of diammonium phosphate and 0.3 kg of potassium dihydrogen phosphate. Spread evenly over the ground, plow and turn 10-12 cm, after turning and mixing evenly and leveling, firm the soil.
③ Seed treatment: lettuce can be sown as dry seed or soaked to promote germination. When sowing dry seed, before sowing first dress the seed with 75% chlorothalonil wettable powder equivalent to 0.3% of the dry seed weight, and sow immediately after dressing; it must not be left overnight.
When soaking seed to promote germination, first soak the seed in clean water at about 20°C for 3-4 hours; after rubbing and washing, drain off the water, put the seed into a wet gauze bag or basin, and place it at 20°C to promote germination, rinsing once a day with clean water, then draining and continuing germination promotion; sprouts can be complete in 2-3 days. When the temperature is too high under natural conditions, germination promotion can be carried out in a well shaft or in a mountain cave, etc., with the temperature best kept at 15-20°C.
④ Sowing: before sowing, water the seedbed thoroughly; while the water has not yet fully seeped away, sieve soil to level the bed surface; after the water seeps away, sieve and spread fine soil 0.1-0.2 cm thick, then sow. The seeding rate per hectare is 375-450 grams. In order to cultivate strong seedlings and prevent the seedlings from becoming leggy high-footed seedlings or weak small seedlings, sowing should not be too dense; generally broadcasting 1 gram per sq m of seedbed is appropriate. To sow evenly, the seed can be mixed with sand and broadcast in 2 passes, then covered with sieved soil 0.3-0.5 cm. To prevent water loss, according to the ground temperature, straw, wheat straw or plastic film can be spread or mulched on the bed surface. To prevent ants, crickets, etc. from gnawing the seeds, after sowing spray dimethoate, dichlorvos, etc. on the bed surface.
⑤ Seedling stage management: generally after sowing, maintain the bed temperature at 20-25°C and keep the bed surface moist; complete emergence can occur in 3-5 days. If the temperature is too high, shade appropriately to create a cool, moist environment to favor healthy seedling growth. When the seedlings have just emerged, promptly remove the covering on the bed surface to prevent the formation of high-footed seedlings caused by excessive elongation of the hypocotyl.
After emergence, keep 18-20°C during the day and 8-10°C at night. 7-10 days after emergence, when the small seedlings have two true leaves and one heart leaf, promptly transplant the seedlings, with a seedling spacing of 3-5 cm. After transplanting, spray or irrigate with water using a 500-fold potassium dihydrogen phosphate solution. During the seedling stage, also spray 1-2 times with 75% chlorothalonil wettable powder or 70% thiophanate-methyl wettable powder at 600-800-fold solution to control seedling stage diseases. When the seedling age is 25-35 days and there are 4-5 true leaves, they can be planted out.
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