Seedling raising technique of lettuce in summer

Because of the low emergence rate of seed treatment in summer, low temperature treatment should be carried out. The method is to soak the seeds for 12 hours, then wrap them with gauze and put them in the refrigerator (2 ℃-5 ℃) for 2 days, then spread them in a cool place, and then sow the seeds after cracking and germinating. Sowing and sowing should prevent sparse and uneven sowing, watering enough bottom water once before sowing, sowing 3 grams-3.5 grams per square meter, covering the ground with sunshade net to cool and moisturize, and remove after emergence. Seedling bed management seedlings should be protected from rainstorm, high temperature and drought in summer, and rain-proof seedlings and sunshade net should be used to cover seedlings. Generally sunny day from 8 am to 4 pm to cover the sunshade net, in the evening or cloudy day to uncover the net. Dry weather should be more watering in the morning and evening, can be combined with watering topdressing, 0.3% potassium dihydrogen phosphate can be used for foliar topdressing.