Using greenhouses, shade nets and other protective facilities, lettuce can achieve annual production and annual supply. First, the selection of winter lettuce lettuce, spring lettuce selected cold-resistant, strong adaptability, late bolting varieties, such as "cold white leaf real", "cold-resistant white skin," "if vine leaves" and so on. Summer and autumn lettuce, the selection of heat-resistant early maturing varieties, such as "Cold-resistant white leaf real", "heat-resistant large flowers" and so on. Second, sowing date to determine the spring lettuce, December to March greenhouse nursery, from mid-February to late March open seedlings. Summer lettuce shoots are cultivated in the open season from April to May, and covered with shade nets from late May to July. Live or high density plants are planted. Lettuce in autumn, from July to September, use shade nets to cover sowing, seedlings transplanting. Overwinter lettuce, October to November open field nursery. Third, nurturing strong seedlings 1 Site preparation: Select the topography of Gaozao, well-drained plots for seedbeds. 5 to 7 days before sowing, per acre Shi organic fertilizer rot 4000 ~ 5000 kg or 50 kg compound fertilizer as base fertilizer. After the soil is applied before the site preparation, it is deeply turned, flattened, and covered with a plastic film to be sown. 2 Seed treatment: During the period from May to September, seed germination is difficult because of the hot and high temperature. Soak the seeds in cold water for 6-7 hours, then use a damp cloth to pack at 20-25°C to 80% of the seeds, or soak them in cold water for 1 or 2 hours, wrap them in a wet cloth and place them in the well. 30 cm above the water, 1 to 2 times a day, 3 to 4 days to germination. Seeds can also be soaked for 24 hours, wrapped in a damp cloth, placed in a refrigerator or freezer, frozen at minus 3 to 5 °C for 24 hours, and then placed in a cool place, 2 to 3 days to germination. 3 sowing: spring lettuce, greenhouse seeding sowing, first uncover the seedlings on the film, pouring enough water, after the water infiltration, the seeds mixed with a small amount of fine sand or fine soil and spread after sowing. 10 to 20 square meters seedbed seeds 25 to 30 grams. After the sowing, the cover soil is 0.3-0.5 cm, the cover film is tight, and the shade net or the straw grass cover is kept warm at night. Open field nursery four cover small shed. Before the seedlings were unearthed, the covers were covered early in the evening and no ventilation was provided to increase the bed temperature. After the seedlings are unearthed, they should be properly ventilated and kept at a bed temperature of 12 to 20°C during the day and 5 to 8°C at night. Sunshade net early cover, 2 to 3 straight leaf time seedlings, seedlings from 4 to 5 cm. 5 to 6 days before transplanting to increase ventilation and hardening seedlings. Summer lettuce, sowing cloudy days. During the middle of April to May, sowing seeds cover film was removed and emerged after emergence. From late May to mid-July, shade nets were covered with small arches or flat sheds until emergence or 2 true leaf anterior seedlings, 4 to 5 true leaf time seedlings, seedlings 10 cm apart. The robust seedlings can also be planted at a high density of about 10 cm. After each time seedlings, room seedlings and transplanting seedlings, combined with watering Shishu diluted manure. In the rainy days, the gutters were drained, and 0.5% urea water was poured about 15 days before planting. Twenty-five days or so after the date of seedling or transplanting, the tender plants can be listed on the market. Lettuce in autumn, before sowing, the bed will be wetted and soaked. After sowing, a layer of 3 to 40% contaminated pig fecal residue and a layer of thin straw or a black shading net, sowing seeds or wet seeds shall be covered. Before the emergence of double-floating surface covered in the seedbed soil, silver gray cover after the emergence of shade net. Sooner or later, water the fertilizer to keep the bed moist and promptly weed the seedlings. Fourth, colonization and management of planting, the choice of a good drainage of loam, per acre applied mature organic fertilizer 4000 to 5000 kg. Leveling and making it 1.2 to 1.5 meters wide. Before raising the seedlings, water the seedbed first. Spring lettuce, seedling age 25 to 30 days, 5 to 6 leaves when the colonization, plant spacing 2027 cm, the depth to bury the first piece of roots and stems is appropriate. Watering after planting. Listed on leaves, the spacing is 1520 cm. Covered with mulching film, the base fertilizer is applied once, and the mulch film is well covered. Greenhouses and open field cultivation, even sunny and warm weather cultivating 1 to 2 times, timely watering topdressing, early feces and ground pouring, keeping the surface moist, when the plants are basically seated, tender plants can be listed, with stems as products, each Mu urea 15 kg 1 ~ 2 times. Autumn lettuce, seedling age 25 days colonization, plant spacing 25 (30 ~ 35) centimeters. Listed on the tender strain, spacing 15 to 20 cm. After selecting cloudy days or planting in the afternoon, water it in time, and use a greenhouse, a small arch or a flat shed to cover the shade net, and then remove it after easing the seedlings. Less cultivator, shallow cultivator, dilute and dilute ground, keep the soil moist, before and after the period of plant sealing, apply 3 to 4 per acre or rot 3000 to 4000 kilograms of human or animal manure, or 2 to 3 times of 15 kilograms of urea. Winter lettuce, seedbed base fertilizer should not be excessive. The seedling age is about 40 days, and the planting is covered with mulching. The spacing (30 to 35) (30 to 40), centimeters. Or after the application of 1 to 2 times light faecal water, such as the following year to adult plants listed, should pay attention to the hardening of the seedlings before the winter, should not be too fertilizer and water, to prevent overgrowth of the seedling stage, frozen before re-applying antifreeze fertilizer and water. In the following year, the weeds were promptly removed, and light cultivators were used once. The top dressing concentration was from small to large. After the stem began to expand, the frequency of topdressing decreased and the concentration decreased. For use of mulch and greenhouse cultivation, adequate base fertilizer should be applied and ventilation management should be observed. V. Harvesting and seed-picking Tendering plants can be harvested at any time before the stems are sufficiently enlarged. When the top leaf of the lettuce is flat, it is suitable for harvesting the stem of the lettuce. Autumn lettuce in order to extend the time to market, can delay harvesting, can be used in sunny days to hand over long points and buds, or the beginning of the rosette period, every 5 to 7 days spray 350 to 500 CCC 2 to 3 times. Lettuce seed collection to keep the winter spring lettuce as a seed, leave the species strain isolation between 1000 meters. Eliminate the growth and robustness of the plants with the characteristic characteristics of the variety. After the period of pulling out, keep the row spacing more than 33cm square, go to the old leaves, increase the fertilizing water, cultivate the soil, promote the growth of lateral branches, and properly remove some branches during flowering, sowing props against lodging. The flowering period should not be short of water. After flowering, irrigation is reduced. 20 to 25 days after flowering, the leaves of the planting plants are normal, and the seeds are brown or silver-gray.
Low Cut Safety Shoes,Safety Shoes For Worker,Skid Resistance Hard Wearing Safety Shoes,Lightweight Safety Shoes
Brightway Shoes Co., Ltd. , https://www.brightwaysafety.com