Plant Cultivation System

Abstract

To provide a plant cultivation system capable of cultivating plants under relatively uniform cultivation conditions. [Solution] The system includes a plurality of bottomed, cylindrical cultivation containers 1 that are open at the top, a bottomed, cylindrical water level adjustment unit 2, a nutrient solution tank 3, and a supply pipe 4. The nutrient solution tank 3 stores nutrient solution. The supply pipe 4 connects the plurality of cultivation containers 1 and the water level adjustment unit 2 in parallel and supplies the nutrient solution from the nutrient solution tank 3 to the plurality of cultivation containers 1 and the water level adjustment unit 2. The water level adjustment unit 2 also includes an overflow opening 22a and a discharge outlet 22c. The overflow opening 22a is located at a predetermined height from the bottom wall 21 of the water level adjustment unit 2, and discharges the nutrient solution that has been supplied through the supply pipe 4 and exceeded the predetermined level to the outside of the water level adjustment unit 2. The discharge outlet 22c is located on or near the bottom wall 21 of the water level adjustment unit 2, and discharges the nutrient solution in the water level adjustment unit 2 to the outside of the water level adjustment unit 2.

Description

[Technical Field]

[0001] The present invention relates to a plant cultivation system for cultivating plants using a nutrient solution. [Background technology]

[0002] Plant cultivation in facilities such as plant factories has been widely practiced. In particular, hydroponic cultivation, which involves irrigation and fertilization using a nutrient solution without using soil, has various advantages, such as the ability to control the composition of the nutrient solution, rapid growth and short shipping time, no need for cleaning due to the absence of soil adhesion, and ease of harvesting. For these reasons, it is widely used in the cultivation of fruit vegetables, leafy vegetables, root vegetables, and the like.

[0003] Hydroponic cultivation includes fixed-substrate cultivation, which uses a fixed substrate made of foam resin, rock wool, or the like, and hydroponic cultivation, which does not use a substrate. When hydroponic cultivation is applied to root vegetables, the edible parts, such as roots, may grow elongated without thickening, thickened without elongation, or branched into multiple parts, resulting in shapes that are inedible. From this perspective, it is preferable to apply fixed-substrate cultivation to root vegetables so that pressure equivalent to the soil pressure experienced in open-field cultivation can be applied to the roots. Furthermore, in order to appropriately apply pressure equivalent to this soil pressure, each root vegetable is often grown in a single cultivation pot.

[0004] For example, Patent Document 1 discloses a root vegetable cultivation device that includes multiple cultivation pots in which water-absorbent granular members are supported by porous members arranged above and below each other. Patent Document 2 also discloses a hydroponic cultivation system in which multiple cultivation containers are connected in parallel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-001813 [Patent Document 2] Japanese Patent Application Publication No. 2017-029144 Summary of the Invention [Problem to be solved by the invention]

[0006] As disclosed in Patent Documents 1 and 2, nutrient solution is supplied to each cultivation pot (cultivation pot, cultivation container) from above. This configuration requires a nutrient solution supply line to be routed from a nutrient solution tank located near the floor to above each cultivation pot, and then piping to supply the nutrient solution to each cultivation pot, resulting in a complex structure. Furthermore, if nutrient solution is supplied from above when culture media are placed in each cultivation pot, differences in the degree of penetration of the nutrient solution will occur due to individual differences in the culture media, making it difficult to create a uniform cultivation environment for the cultivated plants. This problem is particularly prevalent in the cultivation of root vegetables, where the culture media are relatively deep, resulting in inconsistent quality.

[0007] The present invention has been made in consideration of the problems of the conventional technology, and aims to provide a plant cultivation system that can cultivate plants such as root vegetables and fruit vegetables under relatively uniform cultivation conditions. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention employs the following technical means. First, the present invention is premised on a plant cultivation system that cultivates plants by alternately repeating a state in which the roots of a target plant are immersed in a nutrient solution and a state in which the nutrient solution is discharged to expose the roots of the target plant. The plant cultivation system according to the present invention includes a plurality of cylindrical cultivation containers each having an open top and a closed bottom, a cylindrical water level adjusting unit having a closed bottom, and a nutrient solution tank. 、 supply pipe and pumps The nutrient solution tank contains the nutrient solution. The supply pipe connects the plurality of cultivation containers and the water level adjustment unit in parallel, and supplies the nutrient solution from the nutrient solution tank to the plurality of cultivation containers and the water level adjustment unit. The water level adjustment unit also has an overflow opening and a discharge outlet. The overflow opening is located at a position spaced a predetermined height from the bottom wall of the water level adjustment unit, and discharges the nutrient solution that has been supplied through the supply pipe and exceeded the predetermined height to the outside of the water level adjustment unit. The discharge outlet is provided on the bottom wall of the water level adjustment unit or in the vicinity of the bottom wall, without being discharged from the overflow opening Inside the water level adjustment section housed in The nutrient solution is placed outside the water level adjustment unit. Always Discharge. The pump supplies the nutrient solution in the nutrient solution tank to the cultivation containers and the water level adjustment unit. The overflow opening is an opening at the upper end of an overflow pipe composed of a cylindrical body erected on the bottom wall of the water level adjustment unit, and the discharge outlet is provided near the bottom wall of the overflow pipe and is a through-hole penetrating the pipe wall of the overflow pipe. The nutrient solution discharged through the overflow opening and discharge outlet is returned to the nutrient solution tank via the overflow pipe. The pump is driven to continue supplying the nutrient solution to the cultivation containers and the water level adjustment unit through the supply pipe, thereby immersing the roots of the target plants in the nutrient solution. The pump is stopped to discharge the nutrient solution from the cultivation containers, thereby exposing the roots of the target plants.

[0009] The plant cultivation system of the present invention can maintain a constant level of nutrient solution in each cultivation container when supplying nutrient solution to each cultivation container, so that the cultivation environment for cultivated plants can be made relatively uniform even if there are differences in the degree of penetration of the nutrient solution due to individual differences in the culture medium. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a plant cultivation system that can cultivate plants under relatively uniform cultivation conditions. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram showing an example of a plant cultivation system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a longitudinal cross-sectional view schematically showing an example of a water level adjusting unit included in the plant cultivation system according to one embodiment of the present invention. [Figure 3] FIG. 2 is a longitudinal cross-sectional view schematically showing an example of a cultivation container provided in the plant cultivation system according to one embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view schematically showing an example of a culture medium placed in a cultivation container included in the plant cultivation system according to one embodiment of the present invention. [Figure 5] FIG. 2 is a diagram schematically illustrating an example of a culture medium placed in a cultivation container included in the plant cultivation system according to one embodiment of the present invention. [Figure 6] FIG. 10 is a longitudinal cross-sectional view schematically showing another example of a cultivation container included in the plant cultivation system according to one embodiment of the present invention. [Figure 7] FIG. 10 is a schematic configuration diagram showing another example of a plant cultivation system according to an embodiment of the present invention. [Figure 8] FIG. 2 is a longitudinal cross-sectional view schematically showing an example of a water level adjusting unit included in the plant cultivation system according to one embodiment of the present invention. [Figure 9] FIG. 2 is a longitudinal cross-sectional view schematically showing an example of a cultivation container provided in the plant cultivation system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described in more detail with reference to the drawings. Although not particularly limited, in this embodiment, the present invention is embodied in an example where it is applied to the cultivation of root vegetables. Figure 1 is a schematic diagram showing the configuration of a plant cultivation system 10 in this embodiment.

[0013] As shown in FIG. 1, a plant cultivation system 10 of this embodiment includes a cultivation container 1, a water level adjustment unit 2, a nutrient solution tank 3, and a supply pipe 4. The cultivation container 1 has a cylindrical structure with a bottom that is open at the top. Although not particularly limited, in this embodiment, the cultivation container 1 has a cylindrical structure with a bottom. The water level adjustment unit 2 has a cylindrical structure with a bottom, and has the function of maintaining the amount of nutrient solution introduced into the cultivation container 1 at a predetermined amount. Although not particularly limited, in this embodiment, the water level adjustment unit 2 also has a cylindrical structure with a bottom.

[0014] In the plant cultivation system 10, a plurality of cultivation containers 1 (three in FIG. 1 ) and a water level adjustment unit 2 are connected in parallel by supply pipes 4. The supply pipes 4 supply the nutrient solution contained in a nutrient solution tank 3 to each cultivation container 1 and the water level adjustment unit 2 by a pump 41 interposed in the supply pipes 4. In this embodiment, the upstream end of the supply pipes 4 is immersed in the nutrient solution contained in the nutrient solution tank 3, and the downstream end of the supply pipes 4 is connected to the bottom wall 11 of each cultivation container 1 and the bottom wall 21 of the water level adjustment unit 2. Therefore, by driving the pump 41, the nutrient solution in the nutrient solution tank 3 is The nutrient solution is introduced into the interior of each cultivation container 1 and the interior of the water level adjustment unit 2 through the supply pipe 4. In this embodiment, the bottom walls 11 of the cultivation containers 1 and the bottom wall 21 of the water level adjustment unit 2 are arranged at approximately the same height.

[0015] FIG. 2 is a vertical cross-sectional view schematically illustrating an example of the water level adjustment unit 2 included in the plant cultivation system 10 according to one embodiment of the present invention. As shown in FIG. 2, the water level adjustment unit 2 includes an overflow pipe 22 therein. The overflow pipe 22 is configured as a tubular body that is erected so as to penetrate the bottom wall 21 of the water level adjustment unit 2, and an opening 22a at its upper end is disposed inside the water level adjustment unit 2 at a predetermined height from the bottom wall 21. The other end of the overflow pipe 22 is connected to the nutrient solution tank 3. In this configuration, the opening 22a at the upper end of the overflow pipe 22 functions as an overflow opening that discharges the nutrient solution that has been introduced into the water level adjustment unit 2 through the supply pipe 4 and that has exceeded the height of the opening 22a through the overflow pipe 22 to the outside of the water level adjustment unit 2 (here, the nutrient solution tank 3). Although not particularly limited, in this embodiment, the overflow pipe 22 is configured as a cylindrical pipe. In this embodiment, the nutrient solution tank 3 is disposed below the bottom wall 11 of the cultivation container 1 and the bottom wall 21 of the water level adjusting section 2, although this is not particularly limited.

[0016] Furthermore, inside the water level adjusting unit 2, a through-hole 22c is provided near the bottom wall 21, penetrating the pipe wall 22b of the overflow pipe 22. The through-hole 22c functions as an outlet that constantly discharges the nutrient solution introduced into the water level adjusting unit 2 to the outside of the water level adjusting unit 2 (here, the nutrient solution tank 3) through the overflow pipe 22. In this embodiment, the diameter of the overflow opening 22a, the size of the through-hole 22c, and the flow rate of the pump 41 are designed so that the water level of the nutrient solution inside the water level adjusting unit 2 is maintained at the position of the overflow opening 22 when the nutrient solution introduced into the water level adjusting unit 2 is discharged from the overflow opening 22a.

[0017] FIG. 3 is a longitudinal cross-sectional view schematically illustrating an example of a cultivation container 1 included in a plant cultivation system 10 according to one embodiment of the present invention. FIG. 4 is a perspective view schematically illustrating an example of a culture medium 12 arranged in the cultivation container 1 included in the plant cultivation system 10 according to one embodiment of the present invention. FIG. 5 is a view schematically illustrating an example of a culture medium 12 arranged in the cultivation container 1 included in the plant cultivation system 10 according to one embodiment of the present invention. As shown in FIGS. 3 and 4 , an elastic culture medium 12 is arranged inside the cultivation container 1. Although not particularly limited, in this embodiment, the culture medium 12 has a cylindrical shape formed by spirally winding a sponge-like sheet material. The cylindrical culture medium 12 is arranged inside the cultivation container 1 such that the axial direction of the cylindrical culture medium 12 coincides with the axial direction of the cylindrical cultivation container 1. Before being arranged inside the cultivation container 1, the outer diameter of the cylindrical culture medium 12 is larger than the inner diameter of the cultivation container 1, and the culture medium 12 arranged inside the cultivation container 1 presses against the inner wall of the cultivation container 1 by elastic force. This maintains the culture medium 12 in a predetermined position inside the cultivation container 1. The culture medium 12 placed in the cultivation container 1 does not need to be one piece, and for example, a plurality of (for example, three) cylindrical culture media 12 may be placed along the axial direction of the cultivation container 1.

[0018] As shown in FIG. 5 , the sheet-like medium 12 has multiple incisions 13 formed along the entire axial direction of the cultivation container 1 when placed in the cultivation container 1, cutting the sheet in a portion of its thickness. The incisions 13 are aligned along the axial direction of the cultivation container 1 when placed in the cultivation container 1, and thus have the function of promoting penetration of the nutrient solution in the axial direction of the cultivation container 1 when the nutrient solution is introduced into the cultivation container 1. Furthermore, because the incisions 13 do not cut the medium 12, handling the medium 12 is not inconvenient, for example, when rolling the medium into a cylindrical shape. The sheet-like medium 12 may also have multiple incisions 14 formed along the entire axial direction of the sheet, cutting the sheet in a portion of its thickness, perpendicular to the incisions 13. The medium 12 may be made of any known material used as a culture medium, such as foamed resins such as polyurethane foam or rock wool.

[0019] In the plant cultivation system 10 having the above configuration, the pump 41 is driven when supplying the nutrient solution to each cultivation container 1. As the pump 41 is driven, the nutrient solution stored in the nutrient solution tank 3 is introduced into each cultivation container 1 and the water level adjustment unit 2 through the supply pipe 4. At this time, the level of the nutrient solution gradually rises in each cultivation container 1 and the water level adjustment unit 2. At this time, the rise in the water level varies in each cultivation container 1 due to individual differences in the culture medium 12. Furthermore, because no culture medium 12 is placed inside the water level adjustment unit 2, the level of the nutrient solution rises more quickly inside than inside each cultivation container 1.

[0020] When the water level of the nutrient solution inside the water level adjusting unit 2 reaches the overflow opening 22a at the upper end of the overflow pipe 22, the nutrient solution that exceeds the position of the overflow opening 22a is discharged to the outside of the water level adjusting unit 2 through the overflow opening 22a and the overflow pipe 22, so that the water level of the nutrient solution inside the water level adjusting unit 2 is maintained at the position of the overflow opening 22a. At this time, the water level of the nutrient solution inside each cultivation container 1 is lower than the water level of the nutrient solution in the water level adjusting unit 2, and the water levels are not uniform due to individual differences between the cultivation containers 1.

[0021] If the pump 41 continues to operate under this condition, the nutrient solution level in each cultivation container 1 rises and reaches the level in the water level adjustment unit 2. When the nutrient solution level in the cultivation container 1 reaches the level in the water level adjustment unit 2, the nutrient solution level stops rising because there is no head difference. Even if the pump 41 continues to operate, the nutrient solution level in that cultivation container 1 no longer rises. Then, when the nutrient solution levels in all cultivation containers 1 reach the level in the water level adjustment unit 2, the nutrient solution levels in the water level adjustment unit 2 and each cultivation container 1 remain consistent, even if the pump 41 continues to operate. As a result, even if the degree of nutrient solution penetration varies depending on the individual culture medium 12 in each cultivation container 1, the cultivation environment for cultivated plants can be made more uniform than in a conventional configuration in which the nutrient solution is supplied from above. This configuration is particularly suitable for root vegetable cultivation, where the culture medium 12 is relatively deep, because it can promote quality stability.

[0022] Furthermore, when the nutrient solution in the cultivation containers 1 needs to be discharged to supply oxygen to the roots in order to prevent root withering or root rot, the operation of the pump 41 can be stopped. When the operation of the pump 41 is stopped, the supply of the nutrient solution to each cultivation container 1 and the water level adjustment unit 2 through the supply path 4 is stopped. Since the water level adjustment unit 2 continues to discharge the nutrient solution through the through-hole 22c, which serves as an outlet, even after the supply of the nutrient solution is stopped, the level of the nutrient solution in the water level adjustment unit 2 gradually decreases over time. At this time, the water level of the nutrient solution in each cultivation container 1 decreases over time while there is no head difference, i.e., the water level of the nutrient solution in each cultivation container 1 matches the water level of the nutrient solution in the water level adjustment unit 2. When the water levels of the nutrient solution in the water level adjusting unit 2 and the cultivation containers 1 reach the water level determined by the through-holes 22c (in this embodiment, the state where the water levels are aligned with the lower ends of the through-holes 22c), the decrease in the water level of the nutrient solution stops, and drainage of the nutrient solution from each cultivation container 1 and the water level adjusting unit 2 is completed. The pump 41 may be configured to be driven for a specific time at a specific time interval specified in advance using a timer or the like. This allows for control such as driving the pump 41 for 15 minutes every 12 hours. Alternatively, a humidity sensor may be installed in the culture medium 12 in one or more cultivation containers 1, and the pump 41 may be driven when the detected humidity value of the humidity sensor falls below a specific humidity specified in advance.

[0023] As mentioned above, in each cultivation container 1, the culture medium 12 presses against the inner wall of the cultivation container 1 by its own elastic force, so that when the water level rises when the nutrient solution is supplied, its position does not rise due to its own buoyancy, and when the nutrient solution is discharged, its position does not fall due to its own weight.

[0024] As described above, the plant cultivation system 10 can make the cultivation environment for cultivated plants relatively uniform even if there are differences in the degree of penetration of the nutrient solution in each cultivation container 1 due to individual differences in the culture medium 12.

[0025] In the above-described embodiment, a particularly preferred example was described in which the medium 12 was formed into a cylindrical shape by spirally winding a sheet-like material. However, any type of medium can be used as the medium placed in each cultivation container 1. For example, a medium composed of a sponge-like material of any shape can also be used. FIG. 6 is a vertical cross-sectional view schematically illustrating another example of a cultivation container 1 provided in a plant cultivation system 10 according to an embodiment of the present invention. FIG. 6 illustrates an example in which multiple cubic mediums 15 are used. If such multiple mediums 15 were placed directly in the cultivation container 1, the medium 15 would pile up on the bottom wall 11 of the cultivation container 1. In such a configuration, the medium 15 would float in the nutrient solution due to its own buoyancy during the process of introducing the nutrient solution into the cultivation container 1, and would rise within the cultivation container 1 as the nutrient solution level rises. This could result in the medium 15 and the cultivated plants spilling out of the cultivation container 1 through the upper opening of the cultivation container 1. For this reason, this embodiment employs a configuration in which a panel 16 is fixedly supported at a predetermined height above the cultivation container 1 and supports the plants to be cultivated. By adopting such a configuration, it is possible to prevent the culture medium 15 from floating up. Any known method can be used to fix the panel 16 to the cultivation container 1. For example, by configuring the outer diameter of the panel 16 to be larger than the inner diameter of the cultivation container 1, it is possible to fix and support the panel 16 at a desired position within the cultivation container 1 by press-fitting the panel 16 into the cultivation container 1.

[0026] Furthermore, in the above-described embodiment, a particularly preferred configuration has been described in which the supply pipe 4 connecting multiple cultivation containers 1 in parallel also serves as a discharge pipe for discharging the nutrient solution from each of the cultivation containers 1. However, other configurations are also possible. For example, a configuration is also possible in which a drain pipe connecting the cultivation containers 1 to the nutrient solution tank 3 is provided on the bottom wall 11 of each cultivation container 1, and an on-off valve is interposed in each drain pipe. In this configuration, for example, when supplying the nutrient solution to each cultivation container 1, the pump 41 is driven with the on-off valves in a closed state, and when discharging the nutrient solution from each cultivation container 1, the pump 41 is stopped and the on-off valves are opened. This allows the nutrient solution to be discharged from each cultivation container 1 more quickly.

[0027] In the above embodiment, as a particularly preferred example, the overflow pipe 22 is erected on the bottom wall 21, and the upper end opening of the overflow pipe 22 is the overflow opening 22a. However, the overflow opening may be provided in the side wall of the water level adjusting unit 2. In this case, the piping for storing the overflowed nutrient solution in the nutrient solution tank 3 is disposed outside the water level adjusting unit 2.

[0028] In the above embodiment, a configuration in which the supply pipe 4 is connected to the bottom 11 of each cultivation container 1 has been described as a particularly suitable example, but the supply pipe 4 may be connected to a side wall of each cultivation container 1. From the viewpoint of minimizing the amount of nutrient solution remaining inside each cultivation container 1, it is preferable that the supply pipe 4 be connected near the bottom wall 11.

[0029] In the embodiment described above, a configuration employing a cylindrical cultivation container 1 with a bottom has been described. However, with such a configuration, when cultivating root vegetables with long roots, the vertical dimension of the cultivation container becomes long, making it difficult to adopt a multi-tier configuration in which cultivation containers are arranged in multiple tiers in the vertical direction, for example. Therefore, a configuration that allows for a low height will be described below. Figure 7 is a schematic diagram showing a plant cultivation system 20 according to this embodiment. Note that in Figure 7, components that achieve the same effects as those of the plant cultivation system 10 are assigned the same reference numerals as in Figure 1, and detailed description thereof will be omitted below.

[0030] As shown in FIG. 7 , the cultivation container 6 of the plant cultivation system 20 of this embodiment is configured as a cylindrical body with a bottom. However, unlike the cultivation container 1 described above, the cultivation container 6 includes a horizontal section 62. The horizontal section 62 is a portion of the cylindrical body of the cultivation container 6 where the axis is arranged substantially horizontally. The horizontal section 62 is provided between the bottom wall 61 of the cultivation container 6 and the upper open end 63 of the cultivation container 6. In this embodiment, the cylindrical body is a cylinder and includes a cylindrical section 67 rising vertically from the bottom wall 61, a bent section 64 connecting the cylindrical section 67 to the cylindrical section of the horizontal section 62, a cylindrical section 66 having an axis along the vertical direction and one end of which forms the open end 63, and a bent section 65 connecting the other end of the cylindrical section 66 to the cylindrical section of the horizontal section 62. Note that, if the axis of the cylindrical body is the same length, the height of the cultivation container can be reduced as long as at least a portion of the axis is arranged in a direction other than vertical. However, in this embodiment, a configuration including the horizontal section 62 with the axis arranged horizontally is illustrated as a particularly suitable example. In this example, the axis of the horizontal section 62 is not completely horizontal, but is positioned slightly lower on the bottom wall 61 side than on the open end 63 side. This allows the nutrient solution to flow toward the bottom wall 61 side without accumulating in the horizontal section 62 during drainage. The water level adjustment unit 7 of the plant cultivation system 20 has a cylindrical structure with a bottom, similar to the water level adjustment unit 2 described above, and has the function of maintaining a predetermined amount of nutrient solution introduced into the cultivation container 6. Note that while only one cultivation container 6 is shown in FIG. 7 , in the plant cultivation system 20, similar to the plant cultivation system 10, multiple cultivation containers 6 (e.g., three) and the water level adjustment unit 7 are connected in parallel by supply pipes 4. The supply pipes 4 supply the nutrient solution contained in the nutrient solution tank 3 to each cultivation container 6 and the water level adjustment unit 7 via pumps 41 interposed in the supply pipes 4. Note that the bottom walls 71 of the water level adjustment unit 7 are positioned at approximately the same height as the bottom walls 61 of the cultivation containers 6.

[0031] 8 is a vertical cross-sectional view schematically showing an example of the water level adjustment unit 7. Like the water level adjustment unit 2, the water level adjustment unit 7 has an overflow pipe 22 therein. An opening 22a at the upper end of the overflow pipe 22 is disposed at a predetermined height from the bottom wall 71 inside the water level adjustment unit 7. In this example, the opening 22a is disposed at the upper limit position of the nutrient solution supplied into the cultivation container 6, that is, at a position corresponding to the upper end of the culture medium 12 disposed in the cylindrical portion 66. Furthermore, as described above, the overflow pipe 22 has a through-hole 22c penetrating the pipe wall 22b.

[0032] FIG. 9 is a longitudinal cross-sectional view schematically showing an example of a cultivation container 6. As shown in FIG. 9, an elastic culture medium 12 is placed inside the cultivation container 6. As described above, the culture medium 12 placed inside the cultivation container 6 presses against the inner wall of the cultivation container 6 by its elastic force, thereby maintaining the culture medium 12 at a predetermined position inside the cultivation container 6. Note that here, multiple cylindrical culture media 12 are placed inside the cultivation container 6, and the culture media 12 are placed so that the central axes of adjacent culture media 12 overlap. The culture media 12 placed in the bent portion 65 are processed so that their shape matches the shape of the bent portion 65.

[0033] In the plant cultivation system 20 having the above configuration, when the nutrient solution is supplied to the cultivation containers 6, the pump 41 is driven and the nutrient solution stored in the nutrient solution tank 3 is introduced into each cultivation container 6 and the water level adjustment unit 7 through the supply pipe 4. At this time, the level of the nutrient solution gradually rises in each cultivation container 6 and the water level adjustment unit 7. As the introduction of the nutrient solution continues, the level of the nutrient solution reaches the overflow opening 22a at the upper end of the overflow pipe 22. Then, the level of the nutrient solution inside the water level adjustment unit 7 is maintained at the position of the overflow opening 22a.

[0034] At this time, the water level of the nutrient solution inside each cultivation container 6 is lower than the water level of the nutrient solution in the water level adjustment unit 7, and the water levels are not uniform due to individual differences between the cultivation containers 6. If the pump 41 continues to be driven in this state, the water level of the nutrient solution inside each cultivation container 6 will rise and reach the water level of the nutrient solution inside the water level adjustment unit 7. When the water level of the nutrient solution inside the cultivation container 6 reaches the water level of the nutrient solution inside the water level adjustment unit 7, the rise in the water level of the nutrient solution will stop because there is no head difference. That is, even if the pump 41 continues to be driven, the level of the nutrient solution in that cultivation container 6 will not rise any further. As a result, even if the degree of penetration of the nutrient solution varies among the cultivation containers 6 due to individual differences in the culture medium 12, the cultivation environment for the cultivated plants can be made more uniform than in the conventional configuration in which the nutrient solution is supplied from above.

[0035] Additionally, the plant cultivation system 20 provides the same effects as the plant cultivation system 10 described above, and because it is shorter than the plant cultivation system 10, it is also possible to adopt a multi-tiered configuration in which cultivation containers are arranged in multiple tiers in the vertical direction. Note that this effect can also be achieved with a configuration in which, instead of the horizontal section 62, an inclined section is provided in which the cylindrical axis is inclined from the vertical direction (for example, the angle between the vertical direction and the cylindrical axis is 60 degrees). In a configuration in which an inclined section is provided, a bent section 65 as shown in FIG. 9 may be provided above the inclined section to provide an open end 63 that opens upward, or the open end may be formed by simply cutting the upper end of the inclined section along a horizontal plane.

[0036] The above-described embodiments do not limit the technical scope of the present invention, and various modifications and applications are possible within the scope of the present invention. For example, in the above-described embodiments, the number of cultivation containers 1, 6 is three, but the number of cultivation containers 1, 6 is not particularly limited. Furthermore, the materials of the cultivation containers, water level adjusters, supply pipes, and other components of the plant cultivation systems 10, 20 are not particularly limited. Any material, such as polyvinyl chloride, can be used. Furthermore, in the above-described embodiments, the present invention is described as being applied to the cultivation of root vegetables. However, the present invention can also be used for any plants, such as fruit vegetables and leafy vegetables. When applied to plants with relatively short roots, such as fruit vegetables and leafy vegetables, the vertical length of the cultivation containers and water level adjusters can be shortened. Furthermore, in the above-described embodiments, the pump 41 is used to supply nutrient solution to each cultivation container 1, 6 and the water level adjusters 2, 7. However, by positioning the nutrient solution tank 3 higher than the overflow opening, nutrient solution can be supplied to each cultivation container 1, 6 and the water level adjusters 2, 7 by hydraulic head difference without using a pump. In this case, it is preferable that the nutrient solution discharged from the overflow opening is collected in another container and then recovered in the nutrient solution tank using a pump or the like. [Industrial Applicability]

[0037] According to the present invention, plants can be cultivated under relatively uniform cultivation conditions, and the present invention is useful as a plant cultivation system. [Explanation of symbols]

[0038] 1, 6 Cultivation container 2, 7 Water level adjustment section 3. Nutrient solution tank 4 Supply pipe 10, 20 Plant cultivation system 11, 21, 61, 71 bottom wall 12, 15 Medium 22 Overflow pipe 22a Overflow opening 22c Through hole (exhaust port)

Claims

1. A plant cultivation system that cultivates plants by alternately repeating a state in which the roots of the plants to be cultivated are immersed in a nutrient solution and a state in which the nutrient solution is discharged to expose the roots of the plants to be cultivated, A plurality of cylindrical cultivation containers each having an open top and a bottom; a cylindrical water level adjusting part with a bottom; a nutrient solution tank for storing a nutrient solution; a supply pipe that connects the plurality of cultivation containers and the water level adjustment unit in parallel and supplies the nutrient solution from the nutrient solution tank to the plurality of cultivation containers and the water level adjustment unit; an overflow opening disposed at a position spaced a predetermined height from the bottom wall of the water level adjusting unit, for discharging the nutrient solution supplied through the supply pipe and exceeding the predetermined height to the outside of the water level adjusting unit; a discharge port provided on or near the bottom wall of the water level adjustment unit, which constantly discharges the nutrient solution contained in the water level adjustment unit to the outside of the water level adjustment unit without being discharged from the overflow opening; a pump that supplies the nutrient solution in the nutrient solution tank to the cultivation containers and the water level adjustment unit; Equipped with the overflow opening is an opening at the upper end of an overflow pipe formed of a cylindrical body erected on the bottom wall of the water level adjustment unit, the discharge outlet is provided near the bottom wall of the overflow pipe and is formed by a through-hole penetrating the pipe wall of the overflow pipe, and the nutrient solution discharged through the overflow opening and the discharge outlet is received in the nutrient solution tank through the overflow pipe, A plant cultivation system in which the pump is driven to continuously supply nutrient solution to the cultivation container and the water level adjustment unit through the supply pipe, thereby immersing the roots of the plant to be cultivated in the nutrient solution, and the pump is stopped to discharge the nutrient solution from the cultivation container, thereby exposing the roots of the plant to be cultivated.

2. A plant cultivation system as described in claim 1, further comprising a timer that switches between a state in which the pump is driven and a state in which the pump is stopped.

3. The plant cultivation system according to claim 2 , wherein the supply pipes are connected to bottom walls of the plurality of cultivation containers.

4. 4. The plant cultivation system according to claim 3, wherein the supply pipe connecting the plurality of cultivation containers in parallel also serves as a discharge pipe for discharging the nutrient solution from each of the plurality of cultivation containers.

5. Each of the plurality of cultivation containers is a medium having elasticity disposed therein; Equipped with The plant cultivation system according to any one of claims 1 to 4, wherein the culture medium is maintained at a predetermined position within the cultivation container by pressing the culture medium against an inner wall of the cultivation container by the elastic force.

6. Each of the plurality of cultivation containers is A number of culture media disposed therein; a panel fixedly supported at a predetermined height of the cultivation container above the culture medium and supporting a plant to be cultivated; The plant cultivation system according to any one of claims 1 to 4, comprising:

7. The plant cultivation system according to claim 5 , wherein the nutrient solution tank is disposed below bottom walls of the plurality of cultivation containers and a bottom wall of the water level adjustment unit.

8. The plant cultivation system according to claim 6 , wherein the nutrient solution tank is disposed below the bottom walls of the plurality of cultivation containers and the bottom wall of the water level adjustment unit.

9. 8. The plant cultivation system according to claim 7, wherein each of the cultivation containers has, between its upper open end and the bottom wall, an inclined portion in which the cylindrical axis is inclined from the vertical direction or a horizontal portion in which the cylindrical axis is arranged in an approximately horizontal direction.

10. 9. The plant cultivation system according to claim 8, wherein each of the cultivation containers has, between its upper open end and the bottom wall, an inclined portion in which the cylindrical axis is inclined from the vertical direction or a horizontal portion in which the cylindrical axis is arranged in an approximately horizontal direction.

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