First, the selection of varieties to choose a strong cold resistance, disease resistance, strong adaptability of varieties, such as Emperors, Salinas, Great Lakes 659, etc., seedbed should choose to protect the water and fertilizer ability of the fertile sandy loam.
Second, seedling bed preparation because of lettuce seeds small, seedbed tillage requirements are strict, the whole land should be fine, bedding efforts to fine, smooth. The fertilizer 10 kilograms, ammonium phosphate 0.3 kg and phosphoric acid two hydrogen potassium 0.3 kg were applied to each 10 square metre seedbed. Evenly scattering the ground, ploughing over 10~12 cm, ploughing mixed all leveling after solid.
Third, seed treatment lettuce can dry seed sowing, can also soak sprout. Dry seed sowing, before sowing with the equivalent of 0.3% of the seed dry weight of 75% hundred bacteria clear wet powder mixed, immediately after mixing sowing, must not be overnight. Soak the sprout, first with 20 ℃ or so water soaking for 3-4 hours, after scrubbing will drain the water, into a wet gauze bag or basin, placed in 20 ℃ environment sprout, wash 1 times a day with water, drain and then continue to sprout, 2-3 days can be filled with buds. When the temperature is too high under natural conditions, the sprout can be placed in the wellbore or placed in the cave, etc., the temperature is mastered in the 15~20℃ is appropriate.
Four, sowing sowing before the seedbed water, while the water is not oozing, the sieve soil leveling the bed surface, after the water seepage sieve sprinkle 0.1~0.2 cm thick fine soil, and then sow. The amount of 375~450 per hectare is a gram. In order to cultivate seedlings, prevent seedling length and the formation of high-footed seedlings or small seedlings, sowing should not be too dense, generally per square meter seedbed sowing 1 grams is appropriate. In order to sow evenly, the seeds can be mixed with sand 2 times, and then the sieve soil cover 0.3~0.5 cm. In order to prevent water loss, according to the geothermal conditions in the furrow surface scattering straw, wheat straw or covering the film. In order to prevent ants, crickets and other gnawing seeds, after sowing in the bed to spray lotus fruit, Dichlorvos and so on.
Five, seedling management generally after sowing to maintain the bed temperature 20~25℃, the furrow surface moist, 3-5 days can be qi seedlings. If the temperature is too high, should be moderately shading, create a cold and humid environment, in order to facilitate the strong growth of seedlings. When the seedlings are first unearthed, the mulch of the furrow surface should be removed in time to prevent the formation of high-footed seedlings with excessive elongation of the embryo axis. After the seedling 18~20℃ during the day, night 8~10℃. 7-10 days after seedling, when the seedling length has two leaves bent, to timely division seedlings, seedling distance 3~5 cm. After seedling, it shall be sprayed with 500 times times the liquid phosphoric acid two hydrogen phosphate solution or watered with water. Seedling stage should also be sprayed 1~2 75% hundred bacteria clear wetting powder or 70% methyl wet powder agent 600~800, prevention and treatment of seedling disease. Seedling age 25-35 days, long with 4~5 slices of true leaves can be planted.