The concept of moist nursery is proposed in relation to floating seedlings. The so-called moist nursery means that the substrate is placed in the hole of the seedling tray. After seeding, the seedling tray is not placed in the nursery pond nor floated on the nutrient solution. Instead, the seedling tray is placed on the soil surface or an ordinary simple support. Spray on the substrate, always keeping the substrate moist to meet seed germination and tobacco seedling growth. The features of the moist seedling raising technique: The roots are well developed and there is no seedling return period. Flue-cured tobacco seedling raising technology integrates flue-cured tobacco floating seedlings and flue-cured tobacco tray seedlings and planting techniques (second stage seedlings), the seedling stage is wet and dry, and the previous water layer is only 1-2. In the later period, the water supply was artificial, there was no water root, and the lateral roots were well developed. The stems were thick and strong, and the roots grew directly without any seedlings. How to use advanced seedling raising methods combined with scientific management to cultivate flue-cured strong seedlings is the basis for achieving high quality, suitable production, and high efficiency of tobacco leaves. In recent years, due to the development of moist nursery roots, the stems are thick and uniform, and the seedlings have a high seedling rate. The seedlings of tobacco seedlings are transplanted into the field and have strong resistance.
First, the difference between wet seedling method and floating seedling method
Wet seedlings still use artificial substrates to overcome the drawbacks of traditional soil seedlings. The difference with the floating seedling method is that the wet seedling tray is not immersed in the nutrient solution, but is placed on the soil surface or the support, and the temperature of the substrate is relieved from the control of the nutrient solution. The maximum temperature in the matrix of floating seedlings is greater than the highest temperature in the matrix of moist seedlings, but the minimum temperature is lower than the minimum temperature in the matrix of moist seedlings. The temperature difference in the nursery substrate is greater than the wet nursery. Therefore, moist seedlings are more conducive to raising the minimum temperature of the seedling substrate at night, which is conducive to seed germination and tobacco seedling growth. Since wet seedlings do not need to be floating on nutrient solutions, there is no need to consider the depth of seedling trays and the requirements for substrates are not as stringent as for floating seedlings. This method does not require floating ponds. Therefore, the cost of moist seedlings is significantly lower than that of floating seedlings. Floating seedlings are reduced, more easily accepted by farmers, and easier to operate.
Second, several components of moist nursery
1. Matrix: Similar to the matrix used for floating seedlings, but simpler than floating seedlings, the requirements are also relatively coarser than those of floating seedlings, in particular, the requirement for conductivity is not stringent for floating seedlings. The basic raw materials are still peat, crushed plant stalks, expanded pearls, and vermiculite.
2. Seedling tray: Since the moist seedling tray does not need to be floated on the nutrient solution, the material for producing the seedling tray is no longer made of polystyrene foam that is environmentally polluted, but is made of hard polyvinyl chloride and other raw materials. There are 128 holes in the tray, and 162-hole floating seedling trays can also be used.
3, nutrient solution: the same with the floating seedlings, but the way the nutrient solution to supply tobacco seedlings is different from that of floating seedlings. The moist seedling nutrient solution is poured from top to bottom, while the nutrient solution of floating seedlings is infiltrated from bottom to top.
4. Nursery pond: The nursery pond can be built. The specifications and requirements are the same with the floating seedlings, or the nursery ponds can not be built, and the seedling trays can be directly placed on the ground.
5 Nursery Sheds: The architectural specifications and requirements of plastic greenhouses and plastic sheds are floating seedlings.
三ã€Preparation for wet seedlings
1. Selection of nursery sites
Good nursery sites should be selected from leeward sunny, flat terrain, convenient transportation, close to clean water sources, convenient irrigation and drainage, low groundwater level, and no pollution around. With sufficient power supply and open terrain, it is easy to establish standard nursery arch groups. The nursery site requires no more than two years to grow solanaceae and crucifer crops as nursery sites.
2. Preparation of nursery supplies
The preparation of flue-cured tobacco seedlings mainly includes the preparation of nursery substrates, seedling trays, plastic films, arch shelters, seedling-specific fertilizers, seeds, and manpower. Only by preparing the necessary tobacco supplies for nursery stocks and being aware of them can the production of tobacco leaves be carried out in an orderly manner. 1 The moist seedling tray is made of polystyrene, characterized by light texture, supporting substrate and tobacco seedlings, corrosion resistance, and certain mechanical strength. 2 The nursery substrate, which is formed by mixing a floating seedling substrate and fresh non-polluted loess according to a certain proportion, in which the floating seedling substrate requires a light texture and is easy to absorb water, but it is not bad, no rot, no toxic and side effects; fresh loess blocks. 3 Wet seedling special fertilizer, uniform purchase, N:P:K=15:8:15, strictly according to manufacturer's instructions for use. 4 Water, must use unpolluted tap water or food well water for moist nursery water, prohibit the use of pit water. The depth of water in the nutrition pool is strictly controlled within 2 cm. 5 seeds, uniform use of the same year tobacco companies purchased tobacco coating species.
3, substrate loading
The selection of nursery substrate is the key factor in the entire seedling raising technology. The quality of the substrate is directly related to the quality and quantity of the seedlings. Therefore, the best conditions are best formulated by the provincial or municipal companies or county companies, which is beneficial to ensure the matrix quality. The role of the matrix is ​​to provide mechanical support to the tobacco plants and roots; to provide sufficient air for the roots to breathe; and to provide suitable moisture and nutrients for the growth of tobacco seedlings. Among them, coordinating the contradiction between water and gas is the key to selecting and matching substrates. The matrix loading plate includes two steps of disinfection and matrix loading. Any used seedlings should be disinfected before nursery. Disinfection method is to use 0.5-0.1% potassium permanganate solution seedling plate spraying, cover film fumigation 1-2 days, and then rinse with water. Substrate preparation, fresh and clean yellow earth soil, sieved with a sieve with a hole diameter of 1 mm (soil for painting the wall), and then mix the yellow mud soil and the floating seedling substrate in a certain proportion, the mixing ratio is generally 2:8 or 3:7. Generally, each bag is filled with 20-20 seedlings of moist seedlings after being added to the substrate and mixed with a dry matrix. When filling, firstly evenly fill the substrate with the substrate, then use the 1-2 times of the pier, the height of the pier is 10-15cm, scrape the excess matrix with a scraper, make the disc surface smooth, and forbid to compact the matrix by hand or other methods. Prevention of tightness. The requirements for full, uniform and tightness during loading are carefully checked. Ensure that the matrix inside the cavity is filled naturally, not overhead, but tight, should be installed moderately moderate, loose or too tight will affect the number of seedlings of tobacco seedlings.
4, sowing
Sowing should be based on climatic conditions and transfer period to determine the sowing time, sowing time should not be too early to prevent seedling age is too long. The same village is required to broadcast within 1-2 days, and the same township is broadcast within 3-5 days. After the seedlings are mounted on the substrate, use a hand or other tool to drill a 0.3-0.5 cm seed hole, sowing 1-2 seed seeds in each hole, then pressing the surface of the seedling disk with a wooden board or hand to cover the seed after sowing. -3 mm thick substrate. The key to sowing is whether the coated seeds can fully contact the substrate after sowing, absorb water quickly, and cleave and germinate well and take root.
5, fertilization
Tobacco moist nursery should use specially formulated wet nursery special fertilizer, according to the type of fertilizer prepared and the amount of fertilizer used, method of application. Before the seedling plate enters the pond, first add moist seedling water to the nursery pond, no deeper than 2 cm, and then add appropriate amount of floating seedling nutrient solution, and the N concentration is controlled at 150 Hg/kg. In short, when all kinds of fertilizers are applied, the amount of fertilizer should be determined according to the amount of water in the nutrient pool. Each fertilizer should be dissolved, stirred and then put into the pool. Each fertilizer should be separated by 1-2 hours. After fertilization, the fertilizer in the pool is to be stirred evenly, and the pH of the nutrient solution in the pool is often checked. The pH should be maintained between 5.8 and 6.5.
Fourth, moist nursery management technology
1, water management
1 before emergence: strictly control the depth of the nutrient solution in the nursery pool, the maximum does not exceed 2 cm, so that the matrix fully absorb nutrient solution, maintain normal moisture, nutrient supply, ensure that the emergence of a timely and uniform. 2 emergence - before cutting leaves: timely control of water, water depth in the pool to maintain 1 cm, when the pool water dry and the substrate surface began to dry, should promptly add water and fertilizer, but pay attention to pay water fertilizer should not be too late, or the growth of tobacco seedlings will be affected inhibition. 3 After the first cutting of the leaves: spray the nutrient solution and water with a watering can, and the amount of water sprayed is reduced accordingly. The purpose is to promote the growth of the roots of the tobacco seedlings and form a developed root system. 4 seedling stage: reduce the number of watering and watering, mainly intermittent water supply, remove the nursery pool baffle, the bottom of the pool can not have a water layer, ensure that when the roots will be all wrapped in the matrix, the degree of control of water to tobacco seedlings Slight wilting occurs at noon, and it is advisable to restore it sooner or later. In general, the intermittent supply of water and the removal of the baffle plate from the nursery were started 10 days before transplanting.
2, temperature and humidity management
The technical guideline for temperature control is “to prevent the accumulation of temperature in the shed under the premise of preventing high temperatures from burning seedlingsâ€. If the temperature is low in the morning or in the evening, the film on both sides of the shed should be compacted to keep warm. When the temperature in the shed is too high, the film should be uncovered and ventilated and cooled. 1 The management of temperature: The maximum temperature in the shed during the seedling period must not exceed 35°C, and the minimum temperature should not be lower than 12°C; it is best to maintain 28°C in the shed before the grand cross period and 32°C in the shed after the grand cross period. For example, under extreme cold weather, in order to promote the early growth of tobacco seedlings, double-layer insulation measures should be adopted to cover the straw sheds or small sheds on the greenhouse nutrition ponds. However, attention should be paid to the timely removal of the greenhouse films after the temperature rises. High temperature seedlings. In addition, when the temperature is low, auxiliary temperature-increasing measures such as installing electric bulbs in the shed can be adopted to promote the growth of tobacco seedlings. 2Humidity management: Humidity is not a major technical factor in wet seedlings, but due to the use of water seedlings for moist seedlings, and the temperature of the cover film rising sooner or later, the humidity in the shed is usually large, and sometimes a large amount of mist will form on the shed film and drop on Nursery seedlings on disk. In addition, the humidity is too large to grow moss and other algae, so the humidity in the greenhouse cannot be ignored. Generally outside the shed at noon every day, the temperature of the shed can be rolled up and ventilated, so that the relative humidity in the shed can be maintained at 50-70.
3, cutting leaf technology
In moist seedlings, cutting leaves is an essential key technical measure to cultivate strong seedlings. Scientifically, cutting leaves not only can control the growth of tobacco seedlings, making them grow robustly and neatly, but also can promote root growth and development, increase the degree of tobacco seedlings robustness, ensure that tobacco seedlings do not exceed the normal seedling age, and avoid adverse environmental impacts after transplanting. Produce early flowers. Each time cutting leaves should be carried out with no clear water on the surface of the tobacco leaves. Try to choose sunny afternoons. For the first time, the leaves should be grown to 6-7 true leaves and the seedling height should be about 10 cm. When the tobacco seedlings are obviously sealed, the height of the cuts should be 3-4 cm above the growth point of the seedlings. After every 6-8 days pruning, until the seedlings are pruned 3-4 times, the first time when the leaves should be light after the gradual increase, but the degree of each trim should not exceed 1/2 of the area of ​​a single leaf. When cutting the leaves to prevent damage to the heart and leaves, to ensure that the pruning of smoke after the orderly and consistent, to control the effect of promoting small. Leaf cutting is to adhere to sanitary operations, no smoking, tools and hands used after each cut of 1 leaf must be immersed in 5% soapy water or 10% bleach solution, and the fallen leaves and cut pieces must be promptly cleared out of the greenhouse. , and concentrate on handling away from the shed.
4, forging
10 days before transplanting, water control was started. When the seedlings are dismantled, the baffles of the nursery ponds are removed, and the bottom membrane of the ponds is laid along the ditch bottom so as to facilitate the removal of stagnant water; at the same time, the film around the nursery shed is gradually opened to carry out the hardening. It is said that the film can be completely removed 2 days before planting, but if it encounters bad weather, it should be covered in time. The main methods for forging seedlings are: 1 Remove the film from the shed, so that the seedlings are completely exposed to the external environment. 2 Raise the seedling trays on the nursery ponds. When the seedlings in the cultivating trays are wilted, they are moved into the nursery ponds. Generally, the 2-3 days are one cycle. The above two methods can effectively enhance the stress resistance of tobacco seedlings. The actual breeding seedlings can be used in combination with the two methods, and the forging days should be no less than 10 days.
5, seedbed pest control
Adhere to the principle of prevention and comprehensive prevention and control. Smoking is prohibited inside nursery greenhouses. Wash hands with soapy water before performing various agricultural operations to prevent the spread of diseases, especially the spread of viral diseases. In strict accordance with the health operations, we must combine the necessary chemical control, generally in the nursery process, before the operation of the crops such as thinning or cutting the leaves, to spray the virus disease prevention and control agent, so that with the drug operation, transplanting Before the spraying of a virus disease prevention and control agent, so that with the drug transplanting, viral disease prevention and treatment desk can choose to poison grams, bacteria grams of poisonous clear. In the process of seedbed management, if a fungal disease such as damping-off or root black rot is found in the seedbed, the diseased plant should be removed in a timely manner and brought out of the shed for centralized treatment. Noodle or Heida. When conducting chemical control, the concentration of the drug solution should be configured strictly in accordance with the instructions for use of the drug. In sporting seedlings, strict adherence to the principle of “mainly seedbed health care and supplemented by chemical control†should be followed, and attention should be paid to the health of nursery environment and nursery operations, and timely detection of diseases should be found. 1 Seedbed hygiene measures: Non-workers are forbidden to enter the shed. Persons entering the shed need to wash their hands with soapy water. Operators are strictly forbidden to smoke in the shed. They must not wash their hands in the nursery pool; when the smoke seedlings or the seedlings are trimmed, the tools must use soap. Liquid immersion disinfection, trimmed and remaining seedlings should be cleared out of the shed in a timely manner; in the process of opening the ventilation or hardening seedlings should pay attention to the prevention and control of aphids and other pests; seedlings diseased plants should be promptly removed, and remedy. 2 Maintenance of the surrounding environment of the nursery site. The surrounding environment of the nursery site is the main site for transmission of pests and diseases. Therefore, the environment around the nursery site is the key to the prevention and control of wet nursery pests and diseases. The general maintenance measures are: to ensure that there is no piled dung within 20 meters of the nursery shed; to eradicate the weeds around the shed and the drainage ditch, and to disinfect the pesticides regularly, generally using 90 times the 600 times liquid of the trichlorfon and 25 carbendazim 300 times the liquid can be sprayed separately 2-3 times.
6, transplanting
The seedlings reach the seedling standard and can be transplanted when the weather is suitable. If the weather is not good at the time of transplanting, control the growth of tobacco seedlings by cutting the leaves. When transplanting, it requires deep planting, most of the stems buried in the soil, in order to improve the root system, transplanting depth is generally 3-4 cm below the growth point exposed the ground is appropriate. Immediately after transplanting, the rooting water shall be poured and the film shall be covered in time. As soon as possible, the field shall be piped and watered with potassium nitrate to promote the seedlings. (1) Strong seedling standard: seedling age 70-75 days, seedling height 10-18 cm, stem height 6-12 cm, stem circumference 1.8-2.5 cm, leaves 8-10 pieces, leaf color green, root system developed, stem Rod flexibility is good. (2) Requirements for transplanting: 1 Select strong seedlings and concentrate transplanting; 2 Roots to avoid direct contact with fertilizers; 3 Pouring sufficient water to strengthen drought resistance management; 4 Deep planting. Others can be transplanted according to the standard seedling operation.
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