How to raise tobacco seedlings without soil?

How to raise tobacco seedlings without soil? With the gradual application of soilless cultivation technology in production, tobacco soilless seedling technology-direct seeding nutrient solution floating seedling (soilless seedling for short) has been widely popularized in flue-cured tobacco production. The practice has proved that the new technology of soilless tobacco seedling cultivation has the advantages of improving tobacco seedling quality, shortening seedling raising period, prolonging the formation period of tobacco seedling economic yield, reducing the occurrence of diseases and insect pests, reducing production cost and saving production labor. The main technical points are introduced as follows: first, seedling materials and facilities 1. The special fertilizer of seedling material is the special fertilizer of flue-cured tobacco in Yuxi. There are 216 holes (12 × 18 holes, 61 cm × 41 cm) and 187 holes (11 × 17 holes, 61 cm × 41 cm) in seedling trays, which are special plates for soilless seedlings made of molded foam. The substrate is a special substrate for soilless seedling breeding. The nursery site should be selected in a place with flat terrain, low groundwater level, shelter from the wind and the sun, good for heating up, close to clean water sources and convenient transportation. It is forbidden to use potato fields, vegetable fields and tobacco fields to build sheds. two。 The steel frame structure greenhouse of seedling raising facilities is 7.5 meters wide, 3 meters high and 30 meters long. polyethylene drip-free film is selected for greenhouse film (0.1 ±0.02 mm thickness). Two wide nutrient troughs and two narrow nutrient troughs can be built in the shed, which are 29.1 meters long, 1.85 meters wide and 0.15 meters high; the narrow nutrient tanks are 29.1 meters long, 0.85 meters wide and 0.15 meters high. The baffle for each nutrient tank is equally divided into 2 small grooves, which can provide 7.3 hectares of field seedlings. Bamboo and wood structure middle shed: 13.5 meters long, 4.2 meters wide and 2.5 meters wide. Polyethylene drip-free film (thickness 0.1 ±0.02 mm) is selected for greenhouse film. Two nutrient troughs with 1.25 meters wide, 0.15 meters high and 12.5 meters long can be built in the shed. Each nutrient tank is equally divided into two small grooves, which can provide 1.3 hectares of field seedlings. Nutrient tank: the length depends on the length of the plastic greenhouse and the width depends on the number of seedling trays discharged. Second, seedling step 1. The preparation of nutrient solution. Pour water 10 cm deep into the nutrient tank, then add the dissolved tobacco special fertilizer into the tank and mix well, continue to add water to 14 cm deep, and then adjust the pH value to 5.8-6.5. two。 Disinfection of seedling plates. 3. Fill the matrix. First, use clean water to adjust the humidity of the substrate (hold it by hand, it is appropriate to disperse when you land on the ground), and then fill the holes in the sterilized seedling tray (the excess matrix is scraped off with wood blocks). The filling of the matrix should be full, uniform, loose and tight. 4. Sow seeds. Sow 2 coated seeds in each seedling hole, spray water repeatedly with a sprayer after sowing, and require wet spray to ensure that the coated seeds fully absorb water and split. After using the thinning medium to cover the seed 2mm to 4mm thick, the seedling tray can be moved to the nutrient tank for soilless seedling raising. 5. Seedling management ① temperature and humidity management: the management of temperature and humidity is realized by uncovering and covering the greenhouse film. During the period from sowing to emergence, the surface temperature of the seedling tray should be controlled between 20 and 25 ℃ to ensure neat emergence. From seedling emergence to cross stage, heat preservation should be given priority to. Ventilation, cooling and dehumidification should be required in case of high temperature. Attention should be paid to heat preservation above 13 ℃ in the afternoon to prevent tobacco seedlings from freezing due to a sudden drop in temperature. From the cross stage to the mature stage, the temperature in the greenhouse should not rise too high (the maximum should not exceed 35 ℃) to prevent burning the seedlings. In the seedling stage, the seedlings should be refined and the ventilation rate should be increased to make the tobacco seedlings gradually adapt to the external temperature and humidity conditions. In the whole seedling raising process, the number of days with relative humidity greater than 90% shall not last more than 3 days. ② nutrient solution management: in order to ensure the relative stability of nutrient solution concentration and liquid level in the tank, the nutrient solution should be checked every 3-5 days, and clear water should be added to 14 cm depth when the liquid level is less than 14 cm deep. About 30 days after emergence, nutrient solution should be added to supplement nutrition and adjust pH value (the method is the same as before). ③ interseedling and fixed seedling: interseedling determination should be carried out in the small cross stage of tobacco seedlings, that is, the excess tobacco seedlings should be pulled out with tweezers, leaving 1 seedling in each hole and filling 1 seedling in the hole. At the same time, reserve seedlings (2%-3%) are reserved for seedling replenishment. ④ leaf cutting: leaf cutting can make tobacco seedlings grow evenly, neatly and uniformly, prevent tall seedlings, increase the stem diameter of tobacco seedlings and improve the quality of tobacco seedlings. The specific method is: when the tobacco seedling grows to 5 leaves and 1 heart (plant height is about 7 cm), cut flat at 3-4 cm from the growing point, and then prune every 5-7 days until the seedling is mature. Leaf cutting should be carried out after the seedling leaves are dewy dry, at the same time, pruning operators and tools should be disinfected, and the broken leaves after pruning should be cleaned up in time to prevent bacterial infection. Pay attention to day and night ventilation around the shed when refining seedlings. ⑥ disease and insect pest control: tobacco soilless seedling still has the possibility of bacterial infection in the seedling stage, so we must adhere to the policy of giving priority to control and comprehensive control. Mainly do a good job in three aspects: the first is the cleaning and disinfection of environmental facilities; the second is to do a good job of ventilation and dehumidification; the third is to monitor the occurrence of diseases and insect pests and timely remove or use pesticides to prevent and cure the disease. In chemical control, the following agents can be used to control various diseases: using 800x solution of mancozeb or 600x solution of mancozeb to control anthracnose and blight; using 58% metalaxyl manganese zinc solution, aldicarb 900fold solution or Dongwang black 1200 fold solution to control black shank, quenching and root rot; 72% agricultural streptomycin sulfate 3000-fold solution to control wildfire Control mosaic disease with 1000-fold solution of 8% fungus Keduke or 900x solution of Dongwangduxiao. When tobacco aphid is found in the seedbed, imidacloprid 1500 times solution can be used to control the aphid. Click to get more tobacco planting techniques click to get more flower planting techniques