Device and method for dynamically supplying water during tobacco seedling raising

Abstract

The present invention discloses a device and method for dynamically supplying water during tobacco seedling raising, which relates to the technical field of tobacco seedling raising. The technical solution includes a seedling raising pool frame and a seedling raising pool arranged in the seedling raising pool frame. A seedling tray rack and an upper plastic film are sequentially arranged in the seedling raising pool from top to bottom. The seedling tray rack is detachably connected to the seedling raising pool. The upper plastic film is fixedly connected to the inner wall of the seedling raising pool and divides the seedling raising pool into a seedling raising cavity and a water level adjusting cavity from top to bottom. Water pipes are arranged in both the seedling raising cavity and the water level adjusting cavity. A drain pipe is further arranged in the water level adjusting cavity. The upper plastic film can move up and down in the seedling raising pool to adjust the volumes of the seedling raising cavity and the water level adjusting cavity. Through (1) water level setting, (2) adding nutrient solution, (3) adjusting the water supply for tobacco seedlings, and (4) leaf pruning and fertilizing; by adopting a dynamically adjustable water level, the problems of root rot and seedling rot in a high-temperature and high-humidity environment are solved during the cultivation of tobacco seedlings, thereby improving the strong seedling rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of tobacco seedling raising, and particularly relates to a device and method for dynamically supplying water during the process of tobacco seedling raising. Background Art

[0002] Seedling raising is an important link in tobacco leaf production and also the basis for tobacco seed production. Neat and robust tobacco seedlings are an important guarantee for realizing high-quality tobacco leaf production and improved variety breeding. At present, floating seedling raising is a seedling raising method with the most mature technology and the largest popularization area in current tobacco leaf production and tobacco seed production. Due to many advantages such as high seedling raising efficiency, uniform quality of tobacco seedlings, and convenient regulation of tobacco seedling growth, it is deeply welcomed by seedling raising units and tobacco farmers.

[0003] However, tobacco is a dryland crop, and the aerenchyma of its roots is not well-developed. During the process of floating seedling raising, the roots are immersed in the nutrient solution for a long time. Due to the large density of seedlings, the roots require a large amount of oxygen, and the surface of the nutrient solution is covered by the seedling trays, resulting in low dissolved oxygen in the nutrient solution, forming a low-oxygen stress on the roots of tobacco seedlings, inhibiting the growth and development of the roots, and easily causing the problems of root rot and seedling rot, which have a greater impact under high-temperature and high-humidity conditions. Therefore, how to improve the floating seedling raising method, solve the problems of root rot and seedling rot in high-temperature and high-humidity environments, and improve the strong seedling rate has become an urgent technical problem in this field. Summary of the Invention

[0004] The first object of the present invention is to provide a device for dynamically supplying water for tobacco seedling raising, and the second object is to provide a method for dynamically supplying water for tobacco seedling raising. By using a dynamically adjustable water level, the problems of root rot and seedling rot in high-temperature and high-humidity environments are solved during the cultivation process of tobacco seedlings, thereby improving the strong seedling rate.

[0005] The first object of the present invention is achieved as follows: It includes a seedling raising pool frame, and a seedling raising pool arranged in the seedling raising pool frame. Inside the seedling raising pool, a seedling tray rack and an upper plastic film are sequentially arranged from top to bottom. The seedling tray rack is detachably connected to the seedling raising pool. The upper plastic film is fixedly connected to the inner wall of the seedling raising pool and divides the seedling raising pool into a seedling raising cavity and a water level adjustment cavity from top to bottom. Water pipes are arranged in both the seedling raising cavity and the water level adjustment cavity. The water level adjustment cavity is also provided with a drain pipe. The upper plastic film can move up and down in the seedling raising pool to adjust the volumes of the seedling raising cavity and the water level adjustment cavity.

[0006] The second object of the present invention is achieved as follows: The preparation method for this tobacco seedling raising includes the following steps:

[0007] (1)Water level setting: Pour tap water into the seedling-raising cavity until the depth of the tap water in the cavity reaches 10 - 20 cm. Then add ditch water to the water level adjustment cavity until the depth of the ditch water reaches 2 - 8 cm. The water level of the tap water should exceed the seedling tray rack by 1 - 5 cm. Scatter seeds in the seedling tray rack, and continuously add tap water to the seedling-raising cavity according to the water absorption and evaporation loss of the substrate to keep the water level in the seedling-raising cavity exceeding the seedling tray rack by 1 - 5 cm.

[0008] (2)Adding nutrient solution: After emergence in 7 - 8 days, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24). At 15 - 18 days after sowing, thin out the seedlings, determine the number of seedlings per hole, and adjust the water level so that the depth of the upper layer of water accounts for 1 / 2 of the total depth.

[0009] (3)Adjusting the water supply for tobacco seedlings: Starting from 4 p.m. on the 20 - 22nd day after sowing, drain the water in the water level adjustment cavity. The volume of the water level adjustment cavity shrinks, causing the water level in the seedling-raising cavity to drop, so that the seedling tray is separated from the nutrient solution. Then, at 7 p.m., refill the water in the water level adjustment cavity. The volume of the water level adjustment cavity expands, causing the water level in the seedling-raising cavity to rise, so that the nutrient solution submerges the bottom of the seedling tray. On rainy or humid days, start draining the water in the water level adjustment cavity at 3 p.m. to separate the seedling tray from the nutrient solution, and refill the water in the water level adjustment cavity at 7 p.m. so that the nutrient solution submerges the bottom of the seedling tray. Keep the depth of the upper layer of water accounting for 1 / 2 of the total depth until the tobacco seedlings are ready for transplanting.

[0010] (4)Leaf pruning and fertilization: Start leaf pruning 25 - 30 days after sowing. When pruning the leaves for the first time, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24); when the seedling age is 40 - 48 days, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24), and prune the leaves for the second time; when the seedling age is 50 - 60 days, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24), and prune the leaves for the third time.

[0011] The beneficial effects of the present invention are as follows:

[0012] 1. In the present invention, by arranging an upper plastic film inside the seedling-raising pond, the upper plastic film divides the seedling-raising pond vertically into a seedling-raising cavity and a water-level adjusting cavity. Due to the special properties of the upper plastic film, the upper plastic film can move up and down in the seedling-raising pond to adjust the volumes of the seedling-raising cavity and the water-level adjusting cavity. Thus, by adjusting the water volume in the water-level adjusting cavity, under the action of the water volume in the water-level adjusting cavity, the rise or fall of the nutrient solution in the seedling-raising cavity is realized. Thereby, the contact depth between the roots of the tobacco seedlings in the seedling tray rack and the nutrient solution can be controlled, so as to realize the dynamic water supply for cultivating tobacco seedlings. The device has a simple structure and is convenient to operate, effectively preventing and controlling the rate of rotten seedlings in actual tobacco seedling cultivation, greatly reducing the rate of rotten seedlings, and effectively improving the rate of strong seedlings in tobacco seedling cultivation.

[0013] 2. In the present invention, during the tobacco seedling-raising process, it is possible to dynamically supply water according to the growth trend of tobacco seedlings, enabling the roots of tobacco seedlings to balance water absorption and ventilation, significantly improving the oxygen supply situation of the roots, and effectively solving the problems of root rot and seedling rot during the tobacco seedling-raising process.

[0014] 3. In the present invention, during the water management in the tobacco seedling-raising process, the water content in the substrate can be reduced, and the pores in the substrate can be increased, thereby enhancing the stress resistance of the seedlings and improving the overall quality of tobacco seedlings.

[0015] 4. In the present invention, during the water management in the tobacco seedling-raising process, the operation of workers during the seedling-raising process can be reduced, the probability of tobacco seedlings being infected can be lowered, the management efficiency can be improved, and the labor cost can be saved.

[0016] 5. In the present invention, during the water management in the tobacco seedling-raising process, the waste of nutrient solution is reduced, fertilizers can be saved, and the tobacco seedlings will not show a situation of fertilizer deficiency.

[0017] 6. In the present invention, during the water management in the tobacco seedling-raising process, the ditch water flowing through the tobacco field is used in the lower layer, which can not only maintain the water level and water temperature of the seedling-raising pond, but also save tap water and fertilizers, and the ditch water has a low cost and is convenient to obtain. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to actual scale.

[0019] Figure 1 It is a schematic structural diagram of the seedling-raising pond of the present invention.

[0020] In the attached drawings, 1 is a seedling-raising pond frame, 2 is a seedling-raising pond, 3 is a seedling tray frame, 4 is an upper plastic film, 5 is a seedling-raising cavity, 6 is a water level adjustment cavity, 7 is a water delivery pipe, 8 is a drain pipe, and 9 is a lower plastic film. Detailed implementation manners

[0021] The embodiments of the technical solutions of the present invention will be described in detail below with reference to the attached drawings. The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, so they are only examples and cannot be used to limit the protection scope of the present invention.

[0022] It should be noted that unless otherwise specified, the technical terms or scientific terms used in this application should have the ordinary meanings understood by those skilled in the art to which the present invention belongs.

[0023] A device for dynamically supplying water during tobacco seedling raising, including a seedling-raising pond frame 1 and a seedling-raising pond 2 arranged in the seedling-raising pond frame 1. Inside the seedling-raising pond 2, a seedling tray frame 3 and an upper plastic film 4 are arranged in sequence from top to bottom. The seedling tray frame 3 is detachably connected to the seedling-raising pond 2, and the upper plastic film 4 is fixedly connected to the inner wall of the seedling-raising pond 2 and divides the seedling-raising pond 2 into a seedling-raising cavity 5 and a water level adjustment cavity 6 from top to bottom. Water delivery pipes 7 are arranged in both the seedling-raising cavity 5 and the water level adjustment cavity 6. The water level adjustment cavity 6 is also provided with a drain pipe 8. The upper plastic film 4 can move up and down in the seedling-raising pond 2 so as to adjust the volumes of the seedling-raising cavity 5 and the water level adjustment cavity 6; by arranging the upper plastic film 4 inside the seedling-raising pond 2, the upper plastic film 4 divides the seedling-raising pond 2 into a seedling-raising cavity 5 and a water level adjustment cavity 6 from top to bottom. Further, due to the special properties of the upper plastic film 4, at the same time, since the four sides of the upper plastic film 4 are fixedly connected to the inner wall of the seedling-raising pond 2, the upper plastic film 4 is in a relaxed state after being connected to the inner wall of the seedling-raising pond 2. Thus, the upper plastic film 4 can move up and down in the seedling-raising pond 2, so that the spatial division of the seedling-raising cavity 5 and the water level adjustment cavity 6 can be adjusted and changed, and the volumes of the seedling-raising cavity 5 and the water level adjustment cavity 6 can be adjusted; thus, by adjusting the water volume in the water level adjustment cavity 6, the function of lifting or lowering the nutrient solution in the seedling-raising cavity 5 can be realized, so that the contact depth between the roots of the tobacco seedlings in the seedling tray frame 3 and the nutrient solution can be controlled, thereby realizing the dynamic water supply for cultivating the tobacco seedlings. The structure of this device is simple and the operation is convenient. In the actual cultivation of tobacco seedlings, the effective prevention and control of the rotten seedling rate is realized, the rotten seedling rate is greatly reduced, and the strong seedling rate of tobacco seedling cultivation is effectively improved.

[0024] The upper plastic film 4 is a spherical film. Setting the structure of the upper plastic film 4 as a spherical structure makes it easier to realize the up and down movement adjustment of the upper plastic film 4 in the seedling-raising pond 2.

[0025] A lower plastic film 9 is also arranged at the bottom of the seedling-raising pond 2, and the lower plastic film 9 is fixedly connected to the side wall and the bottom of the seedling-raising pond 2.

[0026] Both the water delivery pipe 7 and the drain pipe 8 are provided with water pumps to enhance the working effects of water delivery and drainage.

[0027] The upper plastic film 4 is fixed around the inner wall at the upper end of the seedling-raising pond 2.

[0028] The preparation method of the tobacco seedling raising includes the following steps:

[0029] (1) Water level setting: Fill tap water into the seedling-raising cavity until the tap water in the seedling-raising cavity reaches a depth of 10 - 20 cm. Then add ditch water into the water level adjustment cavity until the ditch water reaches a depth of 2 - 8 cm. The water level of the tap water exceeds the seedling tray rack by 1 - 5 cm. Scatter seeds in the seedling tray rack, and continuously add tap water into the seedling-raising cavity according to the water absorption and evaporation loss of the substrate to keep the water level in the seedling-raising cavity exceeding the seedling tray rack by 1 - 5 cm.

[0030] (2) Adding nutrient solution: After emergence in 7 - 8 days, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24). Perform thinning, final singling, and water level adjustment on the 15th - 18th day after sowing, so that the water depth in the water level adjustment cavity accounts for 1 / 2 of the total depth.

[0031] (3) Adjusting the water supply for tobacco seedlings: Starting at 4 pm on the 20th - 22nd day after sowing, drain the water in the water level adjustment cavity. The volume of the water level adjustment cavity shrinks, causing the water level in the seedling-raising cavity to drop, so that the seedling tray is separated from the nutrient solution. Then add water to the water level adjustment cavity at 7 pm. The volume of the water level adjustment cavity expands, causing the water level in the seedling-raising cavity to rise, so that the nutrient solution submerges the bottom of the seedling tray. On rainy or humid days, drain the water in the water level adjustment cavity at 3 pm to separate the seedling tray from the nutrient solution, and add water to the water level adjustment cavity at 7 pm until the nutrient solution submerges the bottom of the seedling tray. Keep the water depth in the seedling-raising cavity accounting for 1 / 2 of the total depth until the tobacco seedlings are ready for transplanting.

[0032] (4) Leaf pruning and fertilizing: Start leaf pruning on the 25th - 30th day after sowing. When pruning the leaves for the first time, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24). When the seedling age is 40 - 48 days, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24), and prune the leaves for the second time. When the seedling age is 50 - 60 days, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O = 12:8:24), and prune the leaves for the third time.

[0033] In the step of leaf cutting and fertilization, when the seedlings are 60-65 days old, add 800-1000g of dissolved compound fertilizer in the leaf cutting and fertilization. The mixing ratio of the compound fertilizer is: (N:P2O5:K2O=12:8:24), and cut the fourth leaf.

[0034] Hardening of the seedlings begins 48 days after sowing. Open the seedling shed at 3 pm every day, lift out the heavy seedling trays, and place the seedling trays in a cool and dry place for hardening. After hardening the seedlings for 3 hours, put the seedling trays back into the seedling pond.

[0035] The water in the water level regulating chamber is ditch water flowing through the tobacco field.

[0036] Working principle and working process of the present invention

[0037] The upper plastic film 4 is arranged inside the seedling raising pool 2, and the upper plastic film 4 divides the seedling raising pool 2 into a seedling raising chamber 5 and a water level regulating chamber 6 from top to bottom. Due to the special properties of the upper plastic film 4, further, since the four sides of the upper plastic film 4 are fixedly connected to the inner wall of the seedling raising pool 2, at the same time, the upper plastic film 4 is in a loose state after being connected to the inner wall of the seedling raising pool 2, so that the upper plastic film 4 can be moved up and down in the seedling raising pool 2, so that the spatial division of the seedling raising chamber 5 and the water level regulating chamber 6 can be adjusted and changed, and the volume of the seedling raising chamber 5 and the water level regulating chamber 6 can be adjusted; thus, by adjusting the water volume in the water level regulating chamber 6, the effect of lifting or lowering the nutrient solution in the seedling raising chamber 5 is achieved, so that the contact depth between the roots of the tobacco seedlings in the seedling tray rack 3 and the nutrient solution can be controlled, thereby realizing dynamic water supply for cultivating the tobacco seedlings. The device has a simple structure and is easy to operate. In actual tobacco seedling cultivation, it realizes effective prevention and control of the rotten seedling rate, which greatly reduces the rotten seedling rate. The water level in the water level regulating chamber is reduced, and the rate of strong seedlings in tobacco seedling cultivation is effectively improved; 20-22 days after the tobacco seedlings are sown, the water in the water level regulating chamber is drained out at 4 pm every day, and the volume of the water level regulating chamber shrinks, so that the water level in the seedling chamber drops, and the seedling tray is separated from the nutrient solution, and the water in the water level regulating chamber is replenished at 7 pm, and the volume of the water level regulating chamber is expanded, so that the water level in the seedling chamber rises, and the nutrient solution floods the bottom of the seedling tray. In rainy or humid weather, the water in the water level regulating chamber is drained out at 3 pm, so that the seedling tray is separated from the nutrient solution, and the water in the water level regulating chamber is replenished at 7 pm until the nutrient solution floods the bottom of the seedling tray, and the water depth in the seedling chamber should be maintained at 1 / 2 of the total depth, which lasts until the tobacco seedlings are transplanted; compared with the seedling raising method that does not use dynamic water supply in the prior art, the seedling raising method using dynamic water supply can effectively reduce and control the rotten seedling rate and effectively improve the strong seedling rate; the labor for daily management of the seedling bed can be reduced, which effectively saves labor costs; and the seedling raising time is also effectively shortened.

[0038] Example 1

[0039] After sowing MS Yunyan 87 and Honghua Dajinyuan, place them into the seedling-raising pond 2 with a dynamic water supply device through the seedling tray rack 3, and continuously add tap water into the seedling-raising cavity according to the water absorption and evaporation loss of the substrate, with a depth of 15 cm. Add ditch water into the water level adjustment cavity 6, with a depth of 5 cm. After emergence in 7 days, add 800 g of dissolved compound fertilizer (N:P2O5:K2O = 12:8:24). Perform thinning, final thinning, and water level adjustment on the 15th day after sowing. Start adjusting the water supply for the tobacco seedlings 20 days after sowing. Drain the water in the water level adjustment cavity 6 at 4 pm every day, so that the seedling tray is separated from the nutrient solution, and then replenish the water in the water level adjustment cavity 6 at 7 pm, making the nutrient solution submerge the bottom of the seedling tray. When there is rainy or humid weather, drain the water in the water level adjustment cavity 6 at 3 pm and replenish the water in the water level adjustment cavity 6 at 7 pm. Start replenishing water in the seedling-raising cavity 5 to prevent the nutrient solution concentration from being too high, and keep the water depth in the seedling-raising cavity 5 accounting for 1 / 2 of the total depth until the seedlings are transplanted. Start leaf pruning 28 days after sowing. Add another 800 g of dissolved compound fertilizer (N:P2O 5: K2O = 12:8:24) when pruning the leaves for the first time, and add another 800 g of dissolved compound fertilizer when pruning the leaves for the third time. The seedlings become mature 50 days after sowing.

[0040] Control: After sowing MS Yunyan 87 and Honghua Dajinyuan, place them into a common seedling-raising pond with a water depth of 20 cm in the seedling-raising pond, and continuously add tap water into the seedling-raising cavity to keep the water level in the seedling pond. After emergence in 7 days, add 800 g of dissolved compound fertilizer (N:P2O5:K2O = 12:8:24). Perform thinning, final thinning, and water level adjustment on the 15th day after sowing. Start leaf pruning 28 days after sowing. Add another 800 g of dissolved compound fertilizer (N:P2O5:K2O = 12:8:24) when pruning the leaves for the first time, and add another 800 g of dissolved compound fertilizer when pruning the leaves for the second time. Start hardening off the seedlings 48 days after sowing. Open the seedling shed at 3 pm every day, lift out the seedling tray, and harden off the seedlings in a cool and dry place. After hardening off for 3 h, put them back into the seedling pond. The seedlings become mature 55 days after sowing.

[0041] Table 1. Tobacco seedling quality and labor cost under different seedling-raising methods

[0042]

[0043] Note: The labor cost refers to the average number of laborers for seedbed management per day for 100 seedling-raising ponds

[0044] The results show that compared with traditional floating seedling raising, when using the method of dynamic water supply for seedling raising, the rotten seedling rate drops from 5 - 10% to below 0.5%, and the strong seedling rate increases to over 95%; the daily labor for daily management of the seedbed is reduced from 6 person-days to 3 person-days; the seedling maturity time is also shortened by 5 days.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered within the scope of the claims and the description of the present invention.

Claims

1. A device for dynamically supplying water during tobacco seedling raising, comprising a seedling raising pool frame (1) and a seedling raising pool (2) arranged in the seedling raising pool frame (1), characterized in that, Inside the seedling-raising pond (2), a seedling tray rack (3) and an upper plastic film (4) are sequentially arranged from top to bottom. The seedling tray rack (3) is detachably connected to the seedling-raising pond (2). The upper plastic film (4) is fixedly connected to the inner wall of the seedling-raising pond (2) and divides the seedling-raising pond (2) into a seedling-raising cavity (5) and a water level adjustment cavity (6) from top to bottom. Water pipes (7) are arranged in both the seedling-raising cavity (5) and the water level adjustment cavity (6). A drain pipe (8) is further arranged in the water level adjustment cavity (6). After being connected to the inner wall of the seedling-raising pond (2), the upper plastic film (4) is in a slack state, so that the upper plastic film (4) can move up and down in the seedling-raising pond (2), thereby adjusting the volumes of the seedling-raising cavity (5) and the water level adjustment cavity (6). The upper plastic film (4) is a spherical film, and the periphery of the upper plastic film (4) is fixedly connected to the inner wall of the seedling-raising pond (2). A lower plastic film (9) is further arranged at the bottom of the seedling-raising pond (2), and the lower plastic film (9) is fixedly connected to the side wall and the bottom of the seedling-raising pond (2).

2. The device for dynamically supplying water during tobacco seedling raising according to claim 1, characterized in that, Water pumps are arranged on both the water pipe (7) and the drain pipe (8).

3. The device for dynamically supplying water during tobacco seedling raising according to claim 1, characterized in that, The periphery of the upper plastic film (4) is fixed to the inner wall at the upper end of the seedling-raising pond (2).

4. A water supply and seedling raising method for the device of dynamically supplying water during tobacco seedling raising according to claim 1, 2 or 3, characterized in that, It includes the following steps: (1) Water level setting: Pour tap water into the seedling-raising cavity (5) until the tap water in the seedling-raising cavity (5) reaches a depth of 10 - 20 cm. Then add ditch water into the water level adjustment cavity (6) until the ditch water reaches a depth of 2 - 8 cm. The water level of the tap water exceeds the seedling tray rack (3) by 1 - 5 cm. Scatter seeds in the seedling tray rack (3), and continuously add tap water into the seedling-raising cavity (5) according to the water absorption and evaporation loss of the substrate to keep the water level in the seedling-raising cavity (5) exceeding the seedling tray rack (3) by 1 - 5 cm. (2) Adding nutrient solution: After emergence in 7 - 8 days, add 800 - 1000 g of dissolved compound fertilizer. The mixing ratio of the compound fertilizer is N:P2O5:K2O = 12:8:

24. Perform thinning, final singling and water level adjustment 15 - 18 days after sowing, so that the depth of the upper layer of water accounts for 1 / 2 of the total depth. (3) Adjusting the water supply for tobacco seedlings: 20 - 22 days after sowing, start draining the water in the water level adjustment cavity (6) at 4 pm every day. The volume contraction of the water level adjustment cavity (6) causes the water level in the seedling-raising cavity (5) to drop, so that the seedling tray is separated from the nutrient solution. Then add water to the water level adjustment cavity (6) at 7 pm. The volume expansion of the water level adjustment cavity (6) causes the water level in the seedling-raising cavity (5) to rise until the nutrient solution submerges the bottom of the seedling tray. On rainy or humid days, start draining the water in the water level adjustment cavity (6) at 3 pm to separate the seedling tray from the nutrient solution, and add water to the water level adjustment cavity (6) at 7 pm to make the nutrient solution in the seedling-raising cavity (5) submerge the bottom of the seedling tray, and keep the depth of the water in the seedling-raising cavity (5) accounting for 1 / 2 of the total depth until the tobacco seedlings are ready for transplanting. (4)Leaf pruning and fertilization: Start leaf pruning 25 - 30 days after sowing. When pruning the leaves for the first time, add 800 - 1000 g of dissolved compound fertilizer, and the mixing ratio of the compound fertilizer is N:P2O5:K2O = 12:8:24; when the seedling age is 40 - 48 days, add 800 - 1000 g of dissolved compound fertilizer, and the mixing ratio of the compound fertilizer is N:P2O5:K2O = 12:8:24, and prune the leaves for the second time; when the seedling age is 50 - 60 days, add 800 - 1000 g of dissolved compound fertilizer, and the mixing ratio of the compound fertilizer is N:P2O5:K2O = 12:8:24, and prune the leaves for the third time.

5. The water supply and seedling raising method according to claim 4, characterized in that, Start hardening off the seedlings 48 days after sowing. Open the seedling shed at 3 pm every day, take out the seedling trays that are heavy on the seedling tray rack, place the seedling trays in a cool and dry place for hardening off. After 3 hours of hardening off, put the seedling trays back into the seedling raising pool (2).

6. The water supply and seedling raising method according to claim 4, characterized in that, The ditch water in the water level adjustment cavity (6) is the ditch water flowing through the tobacco field.

Images