Flue cured tobacco seedlings

The direct seeding cultivation method of flue-cured tobacco can save labor for seedling raising, transplanting and topdressing; Shorten planting time; Save peat and seedling tray; Save the nursery greenhouse. It was invented by Guizhou Tobacco Research Institute and published in China National Intellectual Property Administration on 20 12,10,21. The operation points of this method are as follows:

Step 1: Arrange the tobacco fields and unpack them one and a half months in advance, apply base fertilizer along the center line of the ridge bottom, then ridging, and wait for rainwater to supplement the moisture in the ridge until the soil moisture is sufficient.

Step 2, punch holes after the rain stops, and apply plant ash mixed with underground insect repellent in the holes.

Step 3, sow seeds in holes, sowing/kloc-0 seeds in each hole, and then spraying transplanting agent into the holes until plant ash and the coated seeds are wet, and covering with plastic film.

Step 4, when the seeds germinate and grow to two leaves with one heart, make holes in the film; when the tobacco seedlings grow to 20 cm high, apply fertilizer again, apply fertilizer to the holes in the roots of tobacco plants, and fill them with soil; after the tobacco plants grow to 50 cm high, uncover the film and cultivate the soil, prevent and control pests and diseases, timely top-wipe the buds, and timely harvest and bake them after maturity. China began to study floating seedling in the late 1990s, and in the 20th century, the area of floating seedling gradually expanded and became the dominant seedling raising method. Floating seedling raising has the advantages of high seedling raising efficiency, saving seedling land, reducing seedling raising labor and reducing disease occurrence, and is welcomed by tobacco farmers. At present, different seedling raising methods are being explored all over the country, such as wet seedling raising method. Floating seedling raising mainly focuses on reducing the amount of peat and reducing the cost. Such as: semi-substrate seedling raising method and sand seedling raising method. But none of them can replace the mainstream floating seedling raising method in operation. It is predicted that floating seedling raising will remain the main way of flue-cured tobacco seedling raising in China for a long time to come.

Tobacco floating seedling raising is a modern seedling raising technology which can be used for large-scale, professional and commercial seedling raising production. There are many key technologies, complicated procedures, high management requirements and difficult to grasp key details. If the operation is not in place, the quality of floating seedlings is low, the stress resistance is poor, and the tobacco seedlings are sick, which affects tobacco production. To cultivate strong tobacco seedlings, we need to focus on four keys: first, strict disinfection throughout the process; Second, scientifically control the network, fertilizer, water and temperature; Third, timely and moderate leaf cutting and seedling hardening; The fourth is to strengthen pest control.

After the emergence of tobacco seedlings, with the increase of temperature, tobacco seedlings grow rapidly, so strengthening management is particularly important. Therefore, it is necessary to focus on cultivating healthy seedlings and strengthen the management of fertilizer, water and temperature.

First, strengthen water and fertilizer management. The principle of pool water management is "shallow first, then deep". After sowing, the temperature is low, and the depth of the pool water should be controlled at about 5 cm. After the big cross, with the temperature rising, the water in the pool will gradually deepen to 10 ~ 15 cm. Fertilizer management, the principle is "less before more". When the first real leaf appears, the first fertilization is calculated according to the plate, each plate is 25g. Nutrient solution fertilizer must be dissolved first, then mixed evenly in several times and applied to the pool water; The second fertilization was carried out when the third true leaf appeared. The amount and method of fertilization were the same as the first one, and the depth of the pool water was 10 ~ 15 cm. The third fertilization is about 15 days after the second fertilization. At this time, tobacco seedlings generally have obvious fertilizer deficiency, and the appropriate amount of fertilizer is 20 grams. Fertilization should be mastered flexibly, and topdressing should be appropriate according to the depth of leaf color.

The second is to strengthen temperature and humidity management. The suitable temperature for seed germination is 25℃ ~ 28℃, and the suitable temperature for seed growth is 20℃ ~ 25℃. Do not go above or below the lower and upper temperature limits. Pay attention to the thermometer and do a good job in heat preservation and cooling management in time. Ventilation is generally carried out when the temperature in the shed is higher than 28℃ at noon, and the shed should be closed for heat preservation in the afternoon. When the temperature drops suddenly, the shed film and sunshade net should be tightly covered and covered with heat preservation. After the second leaf cutting, the shed film should be uncovered, the sunshade net should be gradually removed, and the ventilation doors and windows should be opened in large and medium-sized sheds to make the tobacco seedlings gradually adapt to the external environment and achieve the purpose of hardening seedlings. Due to abnormal weather changes, temperature and humidity management should be flexibly controlled.

The third is to strengthen the management of thinning seedlings, fixing seedlings and cutting leaves. When the tobacco seedlings grow to the small cross stage, thinning can improve the ventilation and light transmission conditions and ensure the uniformity of tobacco seedlings. Before seedling thinning, operators should prepare disinfection facilities and instruments, and disinfect all objects that can contact tobacco seedlings in time. When thinning seedlings, the diseased seedlings and weak seedlings should be removed first, and then the holes should be filled with redundant strong seedlings to ensure that each hole has 1 tobacco seedling; Leaves should be cut in time to adjust the relationship between root system and stem and leaf growth of tobacco seedlings. Disinfection measures should be strictly controlled before leaf cutting, and disinfection should be in place. Cut the leaves for the first time when the tobacco seedlings grow to five true leaves, and subtract 1/2 from the tobacco seedlings that grow too fast, so as to achieve "controlling the big and promoting the small" and promote the tobacco seedlings to grow neatly and consistently. Then cut the leaves once every 6-7 days and 3-5 times to ensure the coordinated growth of the aboveground and underground parts of the tobacco seedlings. Scrape the roots with bamboo, and scrape off the roots that grow outside the bottom hole, so as to improve the toughness of the stem and promote the development of the roots. Every time you cut leaves and roots, you should clean them up, spray pesticides before and after cutting leaves, and disinfect them in time.

The fourth is to strengthen the management of forging seedlings. When tobacco seedlings enter the seedling stage, it is necessary to improve ventilation and light transmission conditions, fill the pool with water, and cut off fertilizer to forge seedlings. Uncover the shed film and open the doors and windows of the large and medium-sized shed, so that the seedlings will change from positive green to light green at seedling stage. The seedling pond with dark green leaves should be changed with water to ensure the improvement of strong seedling rate.

Fifth, strengthen the management of pest control. Pest control should adhere to the principle of "prevention first, comprehensive management", focusing on eliminating pathogens and controlling diseases. Must do a good job of disinfection of nursery sites, nursery sheds, substrates, nursery trays, etc. Once the pathogen center is found, it should be removed in time and sprayed with control chemicals to prevent the spread. Diseases prone to occur at seedling stage are: damping-off, damping-off, black shank, anthracnose, common mosaic and so on. Chlorothalonil, Dixon, Tuitute and zineb can be selected for prevention and treatment, and appropriate drugs should be used according to the instructions. The main pests that harm tobacco seedlings are aphids, slugs, leaf miner and so on. , trichlorfon, Wanling and pirimicarb can be used for control. It is necessary to strictly control the concentration of phosphate fertilizer in nutrient solution, strictly disinfect seedling trays, substrates and pool water, standardize tray loading operation, strengthen ventilation and light transmission, and reduce the harm of algae. Spraying copper sulfate to kill algae when algae appear. Strict control of nutrient concentration of nutrient solution can avoid salt damage. The tobacco seedlings that have produced salt damage should be sprayed with water or replaced with pool water to eliminate them.