Nursery is the primary link in the production of sweet potatoes. Only good seedlings can guarantee timely planting; only strong seedlings can ensure high yields. There are many ways for sweet potatoes to grow seedlings, including greenhouses, sheds, plumbing, and small arch shelters. The most common of these is a small arch nursery, the advantages are: energy saving, simple, easy to learn, easy to grasp, high quality potato seedlings, Miao Qi, Miao Zhuang. Generally about 27 days can be used to pick the seedlings. The time for raising seedlings is stable at a temperature higher than 15°C. In the middle and southern regions of Hebei Province, seedlings are usually raised in mid-March.
1. Build a seedbed. Seedbeds should be sunny and easy to use. The seedbed is generally 1.2 meters wide and 8-10 meters long. This size seedbed is convenient for seedlings and ventilation. Choose a plastic film with a width of 2 meters and a thickness of 0.04 mm. The length of the bamboo or bamboo pole is 2.0 meters. The depth of the bed is about 20 centimeters.
2. Preparation before broadcast. After digging the seedbed, it must be practical and prevent the collapse of soil. About 100 grams of compound fertilizer can be used as a basal fertilizer per square meter to ensure the supply of root nutrients at the late stage of picking and extend the time for picking. If time permits, you can cover the plastic film for 1-2 days to increase the bed temperature.
Seed sowing. The disease-free seed potato was selected and sown on sunny days. The top of the row is upward, so that the potato noodles are all on the same level, so that the upper level is uneven, which will help the cover soil thickness uniform, neat emergence. Seed-planting density is based on the germination characteristics of the variety and the size of the tuber. The germinating ability is stronger and the seedlings of the seedlings are more sparsely populated, whereas the tubers are denser and smaller. The general seed potato requires no more than one-third of the front-to-bottom pressure before and after, and 20-30 kg of seedlings per square meter. Seedlings are too dense, seedlings are fewer, seedlings are more likely to have long stems, and survival is low. During the row of potatoes, a thermometer is placed in the middle of the seedbed, and the thermometer should be inserted at the bottom of the potato block, slightly inclined to observe the temperature.
4. Cover bed soil. After arranging the seed potatoes, sprinkle a layer of string soil and pour the bed water to make the potato blocks and the bed soil close. Finally, spread a top layer of soil about 2 cm thick on the surface of the potatoes. It is advisable to use a bed with a moist surface after bed soil. The bamboo or bamboo poles are arched, inserted at intervals of 1 meter, covered with plastic film, and sealed with wet soil around to promote germination. Can also be covered with a layer of film on the surface of the seedbed, can increase 2 °C -3 °C, remove the film in time to emerge, so as not to burn seedlings.
5. Seedbed management. (1) Control the temperature. The basic principle of management is to "predominantly promote, supplement with refinement, first promote after refining, and catalyze and combine" to ensure proper temperature in different periods. The optimum temperature for seedling emergence (within 10 days of seeding) is 29°C-32°C. It is necessary to ensure that the temperature is not lower than 20°C and not higher than 35°C. During this period, the temperature and ground temperature are relatively low, mainly the heat preservation and temperature increase. The optimum seedling temperature is 27°C-30°C. During this period, the temperature rises quickly. Pay attention to ventilation and prevent rotting. Late hardening seedlings or seedlings, suitable for bed temperature 20 °C -25 °C, to remove the film day and night, improve potato seedlings adaptability under natural conditions, strong seedlings. The whole seedling temperature can be controlled by opening part of the film ventilation and water cooling, from 4 pm to 8 pm the cover straw can play a role in warming and insulation. (2) Moisture. Watering according to the growth needs of potato seedlings and dry and wet soil. Seedlings require more water to keep the moist soil moist and conducive to the differentiation and growth of root seedlings. If there is little watering when the seedlings are planted and the bed soil is too dry, choose to pour in small water in the morning to prevent the bed temperature from falling too much. In the medium term, the growing period of seedlings, the humidity can not be small, it is necessary to properly irrigated the water, keep the bed see dry see wet. The humidity should be small within 5 days before the seedling cultivation in the later period. Dry and wet soil on the bed soil can be used to help the potato seedlings grow stronger. Water can not be too much at all times, soaked so far, so as to avoid potato block due to excessive water, lack of oxygen and moldy rotten. (3) Fertilization. Before the first picking, the tubers and the bed soil have sufficient nutrient supply, and generally do not need to be fertilized. Two or three times after picking the seedlings, the nutrients in the shucks gradually decrease, and the root absorbs more nutrients. At this time, it is necessary to chase some available nitrogenous fertilizers, such as urea, and water them immediately to exert the fertilizer effect and prevent burning seedlings. Fertilization is generally conducted on the second day after picking, to prevent mildewing of non-healing wounds after picking.
5. Disease prevention and control. First, the bed soil is sterilized. Before the row of potatoes, dicamba can be disinfected. The surface of the bed soil is sprinkled with moderate dose of diclofen and the bed soil can be evenly mixed to prevent and treat pests and diseases in the soil. Second, the seed potato is sterilized, and the seeds are sterilized by more than 50%. Dioscorean WP 500 times or 50% thiophanate-methyl wettable powder 500-700 times liquid poured into the surface of seed potatoes, can prevent the occurrence of black spot. In the course of growth of potato seedlings, if it is found that the potato pieces are rotted, the bad potatoes shall be removed in time, disinfected with lime, and buried with good soil to prevent the decay of other potato pieces and the spread of diseases caused by the excessive local temperature and cause rotting.
6. Picking seedlings. When the potato seedling grows to a certain height, picking the seedlings in time, otherwise it will cause weak seedlings due to seedling crowding and affect the growth of seedlings. Strong seedlings standards: potato seedlings 20-25 cm high, seedlings thick 5 mm or so, 6-8 knots, around the continuous, dark green leaves, bed soil on the leaves section does not have roots, bed soil white short, no pests, The seedling age is about 30 days.
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