Rape seedlings generally have the characteristics of short stature, well-developed root system, moderate seedling age, moderate tenderness, and no pests and diseases. Usually the petiole is short and does not exceed half of the total length of the petiole and the leaf blade; Elongated; thick main roots, many lateral roots, wide distribution; leaves 7-8 leaf ages with 6-7 green leaves during transplanting, the number of leaves to be planted early can be less, more at late load, and the leaves are thick, Deep color. Keeping seedbeds is the basic condition for nurturing strong seedlings. For existing rapeseed varieties, suitable seedling density in Putian is generally 90-135 strains per square meter, and about 6-9, 000 strains of fertile seedlings per acre seedbed. When the transplanting is early and the seedling age is small, the area of ​​the seedbed can be appropriately smaller, and the seedbed area for the late planting should be larger. Diluted seeds were sown with 1,000-grain weight of 3 grams. The field emergence rate after sowing was calculated as 80%. The 0.5-kilogram seeds could be planted with 130,000 plants. Therefore, 0.5-0.6 kilograms per acre were sown. Even if the seed weight is 4 grams, the sowing rate per mu is only 0.7-0.8 kg. Sub-seeds are finely seeded and uniform seeding is striven for. Miao Dingmiao seedlings and time to the seedlings when the seedlings, 1 leaf period and then Miao again. Before the 3rd leaf stage, the seedlings should be set at 7-10 cm from the seedlings. The seedlings are going to stay small, stay weak, stay strong, and stay sick. Double-low rapeseed should also pay attention to miscellaneous seedlings in the seedbed, the growth of too large, too small seedlings and leaf shape, color, etc. all the different seedlings removed. Before the promotion of post-control management (1) increase base fertilizer, early application Miao Fei. The fertile plots were used as seedbeds, and the plots with cruciferous vegetables were not suitable for seedbeds. Base fertilizer should be applied with nitrogen, phosphorus, potassium and boron fertilizers. Generally, 15 kg of 45% compound fertilizer is applied per acre seedbed. Early phosphorus deficiency in rapeseeds has a great influence on the establishment of organs and the formation of yield. Even if there is sufficient phosphorus supply in the later period, it cannot be recovered. Therefore, in the phosphorus-deficient soil, the base fertilizer should be increased with phosphate fertilizer to promote the development of the root system, so that the seedlings grow robustly and increase the resistance to plant damage and rooting. Rape is more sensitive to boron, and the lack of boron in the soil can lead to impeded seedling growth and affect future growth. In the breeding process should also pay attention to the application of boron fertilizer, usually borax 0.5-0.75 kg per acre seedbed, the amount should not be too much, otherwise there will be boron poisoning. Before the 3rd leaf stage, a quick-acting fertilizer can be applied in combination with the seedlings and seedlings, so that the seedlings can obtain sufficient nutrients at the 3-5 leaf stage. (2) Maintain a suitable soil moisture content. Rapeseed seeds are small and sowing is generally shallow. When drought occurs, it is necessary to inject enough water before sowing. Stop watering after emergence to promote undershooting of young roots and prevent excessive elongation of young shoots. If the soil moisture is full enough to meet the germination and emergence of the seed, it is generally not watered. (3) control and promote strong. In recent years, the rapeseed bed is mostly dominated by ten sides. Due to insufficient area, the density of seedbeds is large and the growth of the seedlings is crowded. It is easy to cause the shortened stem segments to elongate to form tall plantlets or other abnormally growing seedlings, which seriously affects the increase of yield. Through research and production tests, spraying paclobutrazol at the seedling stage has a significant effect on raising the seedling quality, which can shorten the seedling height by 20-40%, shorten the shortened stem segment by 30-60%, shorten the petiole by 30-50%, and chlorophyll. The content increased by 20-30%, the number of qualified seedlings in the seedbed increased by about 30%, and the seedbed per acre could be planted with more than 2 acres of field. The economic benefit was significant. The amount of paclobutrazol has a certain relationship with the application period. Generally, 15% paclobutrazol wettable powder is used for 40-50 grams per acre in the 3-4 leaf stage of rapeseed. The application period is early, the amount should be less; the application period is late, the amount can be more. (4) Topdressing starts to grow fat. After 5 leaf stage of rapeseed, it is necessary to control the supply of fertilizer and water and promote the accumulation of photosynthetic products. One week before transplanting, topdressing once started to grow fertilizer, with about 10 kilograms of urea per acre, so that the seedlings can absorb a large amount of nitrogen in a short period of time. After transplanting, the seedlings have the ability of anti-implantation, fast rooting, and easy to live. (5) Control of pests and diseases. Timely prevention and control of aphids, cabbage caterpillars, virus diseases and other pests and diseases. Precision Ultrasonic Metal Welding Machine Titanium Welding Machine,Laser Welding Machine For Stainless Steel,Brass Welding Machine,Gas Metal Arc Welding Machine Dongguan Jinwang Ultrasonic Equipment Co.,Ltd , https://www.jwultrasonic.com