Hydroponic cultivation device and plant cultivation method using the same

Abstract

To provide a hydroponic cultivation device and the like that facilitate operation of filling a nutrient solution.SOLUTION: A hydroponic cultivation device 100 includes: a tray section 10 that has an open top and forms a nutrient solution storage space 11 for storing a nutrient solution LQ, the tray section being rectangular in plan view; and a cover section 20 that is plate-shaped, sized to close the nutrient solution storage space 11, and formed with a plurality of openings 26 for inserting and holding pot sections 30 in which seedlings of plants PL are planted. The cover section 20 has the openings 26 arranged in a grid pattern, and a distance D1 from a first longitudinal edge 21 to the opening 26 nearest to the first longitudinal edge 21 is set longer than a distance D2 from a second longitudinal edge 22 to the opening 26 nearest to the second longitudinal edge 22. As a result, the tray section 10, which is closed at the top by the cover section 20 holding the pot sections 30 in a state where their bottoms are suspended, can advantageously be slid open to facilitate the work of supplying the nutrient solution LQ into the nutrient solution storage space 11.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a hydroponics device and a plant cultivation method using the same, and more particularly to a hydroponics device that uses a non-circulating nutrient solution and is used in plant factories and the like, and a plant cultivation method using the same. [Background technology]

[0002] In recent years, various hydroponic cultivation techniques have been developed, using a nutrient solution instead of soil. In particular, plant factories, which use artificial lighting to grow plants indoors, such as in factories, have attracted attention as a stable method for supplying plants unaffected by weather conditions. Known hydroponic cultivation methods include a recirculating system, which circulates the nutrient solution; a flowing water system, which allows the nutrient solution to flow freely; and a non-recirculating or thin-film retention system, in which the nutrient solution is stored in trays. Recirculating hydroponics presents challenges, such as difficulty in maintaining nutrient balance. Another problem is the rapid spread of pathogens that can grow in the nutrient solution. In contrast, thin-film retention hydroponics allows for the concentration of the nutrient solution to be adjusted for each tray, and even if pathogens do occur, they are prevented from spreading to other trays.

[0003] On the other hand, thin-film retention hydroponic cultivation requires the supply of nutrient solution to each tray. It is also necessary to replenish the nutrient solution when it runs out. If the top of the tray is left open to facilitate filling with nutrient solution, light from the open area can penetrate the tray and irradiate the nutrient solution, causing the proliferation of algae and mold present in the nutrient solution, resulting in an unsanitary environment. For this reason, the top of the tray must be closed, which ultimately makes filling with nutrient solution inconvenient. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-123822 Summary of the Invention [Problem to be solved by the invention]

[0005] One object of the present disclosure is to provide a hydroponics device that facilitates the filling of nutrient solution, and a plant cultivation method using the same. Another object is to provide a hydroponics device that facilitates sliding of the cover, and a plant cultivation method using the same. Note that the description of these objects and objects of the present disclosure does not preclude the existence of other objects and objects. Furthermore, it is not necessary for one aspect of the present disclosure to solve all of these objects. Furthermore, it is possible to extract other objects from the description of the specification, drawings, and claims of the present disclosure. Means for solving the objects and effects of the invention

[0006] A hydroponics device according to a first embodiment of the present disclosure is a hydroponics device comprising: a tray portion having an open top surface that forms a nutrient solution storage space for storing nutrient solution and that is rectangular in plan view; and a plate-like cover portion sized to close the nutrient solution storage space and having a plurality of openings for inserting and holding pot portions containing plant seedlings, the cover portion openings in a checkerboard pattern, and a first distance from a first longitudinal edge to the opening closest to the first edge and a second distance from a second longitudinal edge to the opening closest to the second edge. This configuration has the advantage that the tray portion, which closes the top surface, can be slid open by the cover portion, which holds the pot portions with their bottoms raised, facilitating the supply of nutrient solution to the nutrient solution storage space. In other words, by offsetting the openings formed in a checkerboard pattern on the cover part in the longitudinal direction and providing a margin area without openings on the first edge side, when sliding the second edge side of the cover part to open the nutrient solution storage space, it is possible to partially open the nutrient solution storage space of the tray part without the pot part inserted into the opening closest to the first edge interfering with the tray part, making it easier to supply the nutrient solution.

[0007] In addition, in the hydroponics apparatus according to a second aspect, in the above-mentioned aspect, the first distance is greater than the width of the opening.

[0008] Furthermore, in the hydroponics apparatus according to a third aspect, in any one of the above aspects, the first distance is 1.5 times or more the second distance.

[0009] Furthermore, in a hydroponics device according to a fourth aspect, in any of the above aspects, the cover portion has one of the shorter sides of a rectangular shape in a plan view as the first edge, the other shorter side as the second edge, one of the longer sides as a third edge, and the other longer side as a fourth edge, and a third distance from the third edge to the opening closest to the third edge and a fourth distance from the fourth edge to the opening closest to the fourth edge are equal to the second distance.With the above configuration, a margin area is provided only on the first edge of the rectangular cover portion to ensure that the cover portion can slide in one direction, while the margin is reduced on the other edges to ensure an effective area in which openings can be provided, thereby making it possible to avoid a decrease in productivity without reducing the number of pot portions that can be held.

[0010] Furthermore, in the hydroponics apparatus according to form 5, in any of the above forms, at least the upper surface of the cover has a light-blocking property. With the above configuration, the cover that closes the tray portion in which the nutrient solution storage space is filled with the nutrient solution has a light-blocking property, thereby making it possible to prevent external illumination light from passing through the cover portion and irradiating the nutrient solution, thereby preventing the proliferation of photophilic microorganisms such as algae and mold.

[0011] Furthermore, in the hydroponics apparatus according to form 6, in any of the above forms, the cover is made of a black plate material. With this configuration, it is possible to easily impart light-blocking properties to the cover, thereby suppressing the proliferation of photophilic microorganisms such as algae and mold in the nutrient solution.

[0012] Furthermore, the hydroponics device according to a seventh aspect is any of the above-mentioned aspects, and further includes a pot portion formed in the shape of a pot with an open top, which is inserted into the opening of the tray portion with a plant seedling planted in the pot and has its bottom protruding into the nutrient solution storage space, and the pot portion has slits formed from the bottom to the sides, and is configured so that the nutrient solution is supplied to the plant in the pot through the slits when the nutrient solution storage space is filled and the bottom is impregnated with the nutrient solution. With this configuration, it is possible to efficiently supply the nutrient solution from the bottom of the pot portion through the slits.

[0013] Furthermore, in the hydroponic cultivation apparatus according to aspect 8, in any of the above aspects, the culture medium for growing plants contained in the pot of the pot part is made of a compostable biodegradable material. With this configuration, hydroponic cultivation can be realized with less environmental impact than using rock wool or the like.

[0014] Furthermore, in the hydroponics device according to form 9, in any of the above forms, the cover part has a through-hole partially opened. This configuration has the advantage that a rod-shaped object can be inserted into the through-hole to easily slide the cover part.

[0015] Furthermore, a plant growing method according to a tenth aspect is a plant growing method using a hydroponics device, the method including the steps of: storing nutrient solution in a nutrient solution storage space of a tray portion formed in a rectangular shape in a plan view by opening an upper surface thereof to form a nutrient solution storage space; placing a plate-shaped cover portion formed in a size sufficient to close the nutrient solution storage space on the upper surface of the tray portion to close the nutrient solution storage space; and closing a plurality of openings formed in a grid pattern in the cover portion, the openings extending from a first longitudinal edge of the cover portion to the opening nearest to the first longitudinal edge. The method includes the steps of inserting pot parts with plant seedlings planted therein into the plurality of openings arranged so that the first distance between the pot parts and the second longitudinal edge is increased by a second distance from the second longitudinal edge to the opening closest to the second longitudinal edge, thereby allowing the bottom surface of each pot part to be impregnated with the nutrient solution, sliding the cover part to partially open the nutrient solution storage space on the second longitudinal edge side of the cover part when the nutrient solution or the nutrients contained in the nutrient solution becomes insufficient, and supplying the nutrient solution from the partially opened nutrient solution storage space. This has the advantage that the tray part, which closes the top surface of the pot part with the cover part that keeps the bottom surface of the pot part floating, can be slid open, facilitating the supply of the nutrient solution. In other words, by offsetting the openings formed in a checkerboard pattern in the cover portion in the longitudinal direction and providing a blank area without openings on the first edge side, when the second edge side is slid to open the tray portion, it is possible to prevent the pot portion inserted into the opening closest to the first edge from interfering with the tray portion, and to open the tray portion widely, making it easier to supply nutrient solution.

[0016] Furthermore, the plant cultivation method according to form 11, in any of the above forms, further includes the step of removing the seedlings of the plants planted in the pots from the openings and shipping them before they reach commercial size. This allows the seedlings of the plants planted in the pots to be shipped at a stage when they have fully grown and before they interfere with plants in adjacent pots, thereby preventing the leaves of adjacent plants from overlapping and overgrowing, which would hinder their growth. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view showing a state in which the hydroponic cultivation device according to the first embodiment is in use. [Figure 2] FIG. 2 is a plan view showing the hydroponic cultivation apparatus of FIG. [Figure 3] FIG. 3 is a cross-sectional view of the hydroponic cultivation apparatus taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a main part of FIG. 3. [Figure 5] FIG. 10 is a perspective view showing a state in which the pot portion is inserted into the cover portion. [Figure 6] FIG. 3 is a plan view of the cover portion of FIG. 2. [Figure 7] FIG. 2 is a perspective view showing a state in which the cover is slid from the state shown in FIG. 1. [Figure 8] 4 is a cross-sectional view showing a state in which the cover portion is slid from the state shown in FIG. 3. FIG. [Figure 9] FIG. 10 is a plan view showing a hydroponic cultivation apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Embodiments of the present disclosure will be described below with reference to the drawings. However, the embodiments described below are merely examples for embodying the technical concepts of the present disclosure, and the present disclosure is not limited to the following. Furthermore, this specification does not in any way specify the components set forth in the claims to be those of the embodiments. The dimensions, materials, shapes, relative positions, etc. of components described in the embodiments are not intended to limit the scope of the present disclosure, and are merely illustrative examples, unless otherwise specified. The size and positional relationships of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate components that are identical or of the same quality, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present disclosure may be configured with the same components, such that multiple elements are shared by one component, or conversely, the functions of one component may be shared by multiple components.

[0019] The nutrient solution cultivation device of the present disclosure can be used for hydroponic cultivation, which grows plants in a nutrient solution. It is particularly suitable for plant factories that grow plants indoors using artificial lighting instead of sunlight. The nutrient solution cultivation device can also be used to grow herbs such as basil and Italian parsley, lettuces such as leaf lettuce and romaine lettuce, and other plants such as komatsuna, mizuna, mustard greens, and lettuce. An example of use in growing lettuce is described below. [Embodiment 1]

[0020] 1 to 8 show a hydroponics apparatus 100 according to a first embodiment of the present disclosure. In these figures, Fig. 1 is a perspective view showing the hydroponics apparatus 100 according to the first embodiment in use, Fig. 2 is a plan view showing the hydroponics apparatus 100 of Fig. 1, Fig. 3 is a cross-sectional view of the hydroponics apparatus 100 of Fig. 2 taken along line III-III, Fig. 4 is an enlarged cross-sectional view of a main portion of Fig. 3, Fig. 5 is a perspective view showing a state in which the pot portion 30 is inserted into the cover portion 20, Fig. 6 is a plan view of the cover portion 20 of Fig. 2, Fig. 7 is a perspective view showing a state in which the cover portion 20 is slid from the state of Fig. 1, and Fig. 8 is a cross-sectional view showing a state in which the cover portion 20 has been slid from the state of Fig. 3. The hydroponics apparatus 100 shown in these figures includes a tray portion 10 and a cover portion 20. As shown in Figs. 1 to 3, the tray portion 10 has an open top to form a nutrient solution storage space 11 for storing nutrient solution LQ. The cover 20 is placed on top of the tray 10 so as to close the nutrient solution storage space 11 of the tray 10. As shown in FIGS. 3 and 4, the cover 20 holds the pot 30 inserted into its opening 26, suspending the pot 30 so that its bottom is raised above the bottom of the tray 10 and exposed to the nutrient solution storage space 11. In this state, the bottom of the pot 30 is immersed in the nutrient solution LQ stored in the nutrient solution storage space 11, and the nutrient solution LQ is supplied to the culture medium 40 filled in the pot 30, thereby cultivating the plants PL planted in the culture medium 40. The nutrient solution LQ is not circulated but remains in the tray 10 in a thin film retention system. Therefore, even if bacteria or pests occur in one tray, they will not spread to other trays. Each component is described in detail below. (Tray part 10)

[0021] The tray section 10 is formed in a thin box shape with an open top. It is also formed in a rectangular shape extending in one direction in plan view. In the example of FIGS. 1 and 2, it is a rectangular shape elongated in the left-right direction in plan view. A nutrient solution storage space 11 for storing the nutrient solution LQ is formed inside the tray section 10, and the top side is an open surface. Such a tray section 10 can be made of a rigid material such as resin or metal. Examples of resins that can be used to make the tray section 10 include polycarbonate, polypropylene, polyethylene, and polystyrene. Preferably, a plastic food container, which is easily available and inexpensive, can be used as the tray section. When the tray section is made of metal, stainless steel or aluminum can be used. The shape of the tray section is not limited to this, and any shape can be used, such as a round tub or a polygonal shape. (Cover part 20)

[0022] The cover part 20 is formed in a plate shape. The cover part 20 is formed to a size that closes the upper surface of the nutrient solution storage space 11 of the tray part 10. In the examples of Figures 2, 5, and 6, the cover part 20 is formed in a rectangular shape that is slightly larger than the footprint of the upper surface of the tray part 10. Such a cover part 20 can be made of resin, polystyrene foam, cardboard, etc. In the example of Figure 1, etc., the cover part 20 is made of plastic cardboard. (Opening 26)

[0023] The cover 20 also has multiple openings 26. As shown in FIG. 4, each opening 26 is large enough to accommodate a pot 30 containing a plant PL seedling, without the pot 30 passing through the opening 26 and supporting the center of the pot 30. Therefore, the openings 26 are formed according to the shape and size of the pot 30 being used. The multiple openings 26 are also equally spaced at a fixed pitch. The spacing between the openings 26 is preferably wide enough to provide sufficient strength to support the pot 30 while avoiding interference between leaves on the top surface or roots on the bottom surface of adjacent pots 30 when the plants PL are growing in them. In the example shown in FIG. 6, each opening 26 is a 67 mm square, with a 50 mm pitch. There are 12 openings in a 3 x 4 grid pattern. However, the size, shape, number, and arrangement of the openings are not limited to this example and can be designed depending on the tray or pot used, the type of plant being grown, and other factors.

[0024] At least the upper surface of the cover 20 is preferably light-blocking. By providing the cover 20 with light-blocking properties, the nutrient solution storage space 11 of the tray 10 can be closed with the cover 20 while the nutrient solution LQ is filled in the nutrient solution storage space 11, as shown in FIG. 1 , preventing external illumination light from passing through the cover 20 and irradiating the nutrient solution LQ, thereby preventing the proliferation of photophilic microorganisms such as algae and mold. Light-blocking properties refer to the ability to block the wavelength of illumination light or the spectrum of light absorbed by the target plant PL. When a semiconductor light-emitting element such as an LED is used as the illumination light source LS, light-blocking properties refer to the ability to block the wavelength of the illumination light emitted by such a light-emitting element. Specifically, a light-absorbing layer may be formed on the surface of the tray, or a light-reflecting layer may be provided, or a light-blocking filter may be layered on top of the surface.

[0025] It is also preferable to configure the cover 20 from a black plate material, which makes it possible to easily provide the cover 20 with light-blocking properties. (Pot part 30)

[0026] A pot 30 is inserted into each opening 26 of the cover 20. Each pot 30 is formed in the shape of a pot with an open top. When a seedling of a plant PL is planted in the pot, the pot 30 is inserted into the opening 26 of the tray 10, with its bottom projecting into the nutrient solution storage space 11. In this state, as shown in FIG. 4 , the bottom of the pot 30 is suspended above the bottom of the nutrient solution storage space 11 of the tray 10. In other words, the cover 20 suspends the pot 30. In this manner, the cover 20 functions as both a light-shielding member and a hanger for suspending the pot 30. The distance between the bottom of the pot 30 and the nutrient solution storage space 11 is set to a height that allows sufficient supply of nutrient solution LQ to the bottom of the pot 30 and does not prevent roots of the plant PL from growing from the bottom of the pot 30, while also allowing the tray 10 and the hydroponics device 100 to be low in height. In particular, by providing a gap in the bottom surface of the pot portion 30, roots can grow into the space in this gap. As a result, it is possible to prevent roots growing from the slits 32 of the pot portion 30 from spreading out laterally and becoming entangled with roots growing from adjacent pot portions 30. In the example of Figure 4, the distance between the bottom surface of the pot portion 30 and the nutrient solution storage space 11 is about 10 mm. (Slit 32)

[0027] Furthermore, it is preferable that the pot portion 30 has a slit 32 formed from its bottom surface to its side surface. This allows the nutrient solution LQ to be filled into the nutrient solution storage space 11, and the nutrient solution LQ to be supplied to the plant PL in the pot through the slit 32, with the bottom surface of the pot portion 30 being impregnated with the nutrient solution LQ. Furthermore, the slit 32 allows some of the roots of the grown plant PL to extend outward. (Medium 40)

[0028] Each pot portion 30 is preferably filled with a culture medium 40. Using the culture medium 40 instead of soil improves water absorption and water retention, reduces pest infestation due to the lack of soil, reduces the risk of pathogenic bacteria, and improves handling. Reusable rock wool is a common culture medium. However, since rock wool is considered industrial waste, from the perspective of environmental impact, a culture medium made of compostable, biodegradable materials is preferable. This reduces industrial waste and enables hydroponic cultivation with a low environmental impact. A culture medium derived from sphagnum moss can be used for this purpose. For example, Mosswool (registered trademark) from Novarbo, a Finnish company, is suitable. Mosswool can be composted together with plant residues, which is advantageous in terms of disposal costs. (LQ nutrient solution)

[0029] The nutrient solution storage space 11 is filled with the nutrient solution LQ. The nutrient solution LQ does not need to fill the nutrient solution storage space 11 completely; it is sufficient as long as it is an amount sufficient to grow the plants PL. Specifically, it is sufficient for the nutrient solution LQ to be sufficient to impregnate a certain distance from the bottom of each pot portion 30. In the example of FIG. 4, the amount of the nutrient solution LQ is controlled so that the water level is 15 mm to 20 mm from the bottom of the nutrient solution storage space 11. In this way, the bottom of the pot portion 30 is immersed in the nutrient solution LQ stored in the nutrient solution storage space 11, and the nutrient solution LQ is supplied to the culture medium 40 filled in the pot portion 30, and the plants PL planted in the culture medium 40 are grown.

[0030] The pH and EC value of the nutrient solution LQ are controlled in accordance with the water level, as well as the type of plant PL being grown. In general, it is preferable to maintain the pH at a slightly acidic level of 5.5 to 7.0. It is also preferable to maintain the EC value at 0.6 to 1.5 mS / cm for fruit vegetables and 1.2 to 3.5 mS / cm for leaf and root vegetables. Existing liquid fertilizers can be used for this type of nutrient solution LQ. In the example shown in Figure 4, OAT Houses No. 1 and No. 2 manufactured by OAT Agrio Co., Ltd. are used. (offset structure)

[0031] 6, the cover part 20 has a first distance D1 longer from the first longitudinal edge 21 to the opening 26 closest to this first edge 21, and a second distance D2 longer from the second longitudinal edge 22 to the opening 26 closest to this second edge 22. This configuration has the advantage that, as shown in FIGS. 7 and 8, the cover part 20 holds the bottom of the pot part 30 in a floating state, and the tray part 10 that closes the top surface can be slid open, facilitating the operation of supplying the nutrient solution LQ to the nutrient solution storage space 11. That is, by offsetting the openings 26 formed in a grid pattern in the cover portion 20 in the longitudinal direction and providing a blank area 28 without openings 26 on the first edge 21 side, when the second edge 22 side of the cover portion 20 is slid to open the nutrient solution storage space 11, it is possible to partially open the nutrient solution storage space 11 of the tray portion 10 without the pot portion 30 inserted into the opening 26 closest to the first edge 21 interfering with the tray portion 10, thereby facilitating the supply of nutrient solution LQ.

[0032] Compared to recirculating or flow-through systems, thin-film retention hydroponics allows for the concentration of nutrient solution to be adjusted for each tray, allowing for the cultivation of a variety of plants in an environment suited to each. Another advantage is that even if pathogens do occur, their spread to other trays is prevented. On the other hand, nutrient solution must be supplied to each tray, and nutrient solution must be replenished when it runs low. Leaving the top of the tray open to facilitate refilling the nutrient solution presents a problem: light from the open area can penetrate the tray, causing the proliferation of photophilic microorganisms (algae, mold, etc.) present in the nutrient solution and creating an unsanitary environment. Because water does not flow within the tray, this is particularly likely to lead to the growth of microalgae such as diatoms, known as blue-green algae. Blue-green algae act as a breeding ground for pathogens and, by adhering to roots, inhibit nutrient absorption.

[0033] To prevent the occurrence of such water-green algae, the tray section 10 is constructed with a light-blocking material to close off the nutrient solution storage space. However, this does not allow the nutrient solution to be replenished. Removing the cover section only when replenishing the nutrient solution is time-consuming, and the amount of work becomes enormous, especially when there are a large number of tray sections.

[0034] Therefore, in this embodiment, as described above, the cover part 20 is slid slightly on the top surface of the tray part 10 to open or empty part of the nutrient solution storage space 11, thereby making it easy to ensure space for refilling the nutrient solution LQ. For this reason, a flat surface or a flange is provided on the top surface of the tray part 10 to make it easier to slide the cover part 20 on the top surface of the tray part 10. The bottom surface of the cover part 20 is also flat.

[0035] On the other hand, if the openings are positioned right up to the edge of the cover, pots inserted into openings close to the edge will interfere with the tray and prevent proper sliding. While sliding is possible if the pots closest to the edge are removed before sliding, it is time-consuming to remove the pots along the edge each time the nutrient solution is replenished and then reinserted afterward. To avoid this, if openings are positioned away from the edge, the effective area available for openings in the limited area of ​​the cover would be narrowed, reducing the number of openings and the number of pots per tray, thereby reducing production efficiency. Therefore, in the hydroponic cultivation apparatus 100 of this embodiment, as shown in FIG. 8 , an opening 26 is positioned away from one edge of the cover 20—specifically, the edge that is pushed out during sliding—to create a marginal area 28 without openings 26. On the other hand, the margin area 28 is not provided on each edge of the cover part 20, but is secured only on the side that protrudes from the tray part 10 when the cover part 20 is slid, thereby minimizing the margin area 28 and securing an effective area EA in which the opening 26 can be provided as shown in Fig. 6, and allowing more pot parts 30 to be inserted into the cover part 20. In Fig. 6, the effective area EA is indicated by a dashed diagonal line.

[0036] 6, one of the short sides of the rectangular cover portion 20, the right side in the figure, is defined as a first edge 21, and a blank area 28 without the cover portion 20 is provided. By providing the blank area 28 on the short side rather than the long side, the area of ​​the blank area 28 can be reduced, making it easier to secure an area for providing the opening 26.

[0037] Furthermore, in the example shown in FIG. 6 , the margins on the long sides are reduced to ensure a larger area for providing the openings 26. Specifically, when viewed from above, the cover 20 has a rectangular shape, with one short side defined as a first edge 21, the other short side defined as a second edge 22, one long side defined as a third edge 23, and the other long side defined as a fourth edge 24. A third distance D3 from the third edge 23 to the opening 26 closest to the third edge 23 and a fourth distance D4 from the fourth edge 24 to the opening 26 closest to the fourth edge 24 are both approximately equal to the second distance D2. In this way, the margin area 28 is provided only on the first edge 21 on the short sides of the rectangular cover 20 to ensure that the cover 20 can slide in one direction, while the margins on the other edges are reduced. This ensures an effective area EA for providing the openings 26, thereby avoiding a decrease in productivity without reducing the number of pots 30 that can be held.

[0038] The first distance D1 is preferably greater than the width of the opening 26. This makes it possible to slide the cover part 20 a distance that is at least greater than the width of the opening 26. Furthermore, the first distance D1 is preferably 1.5 times or more the second distance D2. Note that a liquid supply nozzle NZ or the like is used to supply or replenish the nutrient solution LQ. [Plant growing method using a hydroponic cultivation device]

[0039] Here, a plant growing method using the hydroponics apparatus 100 will be described. First, the nutrient solution LQ is stored in the nutrient solution storage space 11 of the tray unit 10. Meanwhile, the plate-shaped cover unit 20 is placed on the top surface of the tray unit 10 to close it. Furthermore, pot units 30 with seedlings of plants PL planted therein are inserted into each opening 26 of the cover unit 20. Either of these steps may be performed first. Note that if the cover unit 20 is placed on the top surface of the tray unit 10 to close it before the step of storing the nutrient solution LQ in the nutrient solution storage space 11, the nutrient solution LQ can be supplied to the nutrient solution storage space 11 by sliding the cover unit 20 to partially open the nutrient solution storage space 11, or by using the openings 26. Furthermore, if the pot part 30 is set on the cover part 20 before the process of storing the nutrient solution LQ in the nutrient solution storage space 11, the cover part 20 can be slid to partially open the nutrient solution storage space 11, and the nutrient solution LQ can be supplied to the nutrient solution storage space 11.

[0040] In this way, the bottom surface of each pot portion 30 is impregnated with the nutrient solution LQ. By leaving them in this state, the plants PL planted in each pot portion 30 will grow by absorbing the nutrient solution LQ with their roots. Alternatively, multiple tray portions 10 may be prepared, and cover portions 20 and pot portions 30 may be set on each of them to grow multiple types of plants PL. The plants PL may be the same type in each tray portion, or different types of plants may be planted in each tray portion.

[0041] In such a hydroponics apparatus 100, as the growth of the plants PL progresses in each tray section 10, the amount of nutrient solution LQ may decrease in some tray sections 10 due to evaporation or as a result of differences in the amount of nutrient solution LQ absorbed by each tray section 10 depending on the type of plant PL and individual differences. In such cases, it becomes necessary to replenish the nutrient solution. Also, even if some nutrient solution remains, certain nutrients contained in the nutrient solution may become scarce, causing an imbalance in the nutrients in the nutrient solution. In this case, it is necessary to replenish the nutrients that have become relatively scarce. In either case, it is necessary to replenish the nutrient solution storage space 11 of the tray section 10 with nutrient solution or liquid fertilizer containing a large amount of certain nutrients.

[0042] In this case, the cover part 20 is slid so as to partially open the nutrient solution storage space 11 on the second longitudinal edge 22 side of the cover part 20. The nutrient solution LQ is then supplied from the partially opened nutrient solution storage space 11. In this way, by sliding the cover part 20 on the top surface of the tray part 10 to partially open it without lifting the entire cover part 20, a space capable of supplying the nutrient solution LQ can be secured, facilitating the refilling operation. Furthermore, by arranging the multiple openings 26 so as to be offset in the longitudinal direction of the cover part 20, a marginal region 28 is formed on the first edge 21 that is pushed out by the slide. As a result, even if the cover part 20 is slid longitudinally while holding the pot part 30, the pot part 30 inserted at the leading edge in the sliding direction can be prevented from interfering with the inner wall of the tray part 10.

[0043] With this plant cultivation method, the nutrient solution LQ is neither circulated nor discharged, so there is no need for a circulation mechanism or a drainage mechanism, which makes maintenance easy, minimizes capital investment, and enables plant cultivation in a small space. Furthermore, because the nutrient solution LQ is stored in the tray section 10 and added with simple level control, the effort required for cultivation and maintenance can be minimized.

[0044] The cover part 20 can be slid manually by the user of the hydroponic cultivation apparatus 100. However, an electric drive unit may be provided in the cover part or the tray part so that the sliding can be performed automatically.

[0045] Changes in nutrients in the nutrient solution LQ can be determined, for example, by measuring the EC value. A pH adjusting solution may be added to maintain the pH of the nutrient solution LQ at a neutral or slightly acidic level. To simplify the explanation, in this disclosure, the type of liquid supplied to the tray unit 10 will not be distinguished as nutrient solution, liquid fertilizer, pH adjusting solution, etc., but will be collectively referred to as replenishment or supply of nutrient solution.

[0046] In this way, the pot portion 30 can be removed and harvested and shipped once the plants PL have grown to a desired size. The desired size refers to a growth level generally required in the market, such as a size that allows planting from the pot (called commercial size). Alternatively, plants can be shipped slightly earlier. As plants grow larger, they may protrude from the pot portion 30 and interfere with plants in adjacent pots. This can lead to overlapping of overgrown leaves, potentially impeding growth. To avoid this overlap, plants are harvested and shipped before reaching commercial size. The plants can then be grown at destinations such as plant wholesalers, retailers, and restaurants, where they can be harvested, sold, cooked, and otherwise handled. This approach is particularly advantageous for plant factories equipped with hydroponic cultivation systems, as pots with overgrown leaves require a large amount of management space, making maintenance and provision difficult. [Embodiment 2]

[0047] Furthermore, through holes may be partially formed in the cover portion. Such an example is shown in Fig. 9 as a hydroponic cultivation apparatus 200 according to embodiment 2. In this figure, the same components as those in embodiment 1 described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate. (Through hole 27)

[0048] The hydroponics device 200 shown in FIG. 9 has through-holes 27 at two locations on the left and right sides of the cover part 20B in the longitudinal direction. By inserting a rod-shaped object into these through-holes 27, it is possible to advantageously slide the cover part 20B easily. The through-holes 27 can also be used to supply the nutrient solution LQ to the nutrient solution storage space 11. The size of the through-holes 27 is, for example, about 20 mm in diameter. It is also preferable that the through-holes 27 be closed with a plug or the like when not in use. This makes it possible to prevent light from entering the nutrient solution storage space 11 and causing the growth of blue-green algae and the like.

[0049] Furthermore, as shown in Fig. 9, an arrow 29 indicating the sliding direction may be displayed on the top surface of the cover part 20B. This allows the user of the hydroponic cultivation device to easily and visually understand the sliding direction. The arrow 29 may be attached to the surface of the cover part 20B with a sticker or the like, or may be engraved or printed. [Industrial Applicability]

[0050] The hydroponic cultivation apparatus and plant growing method according to the present invention can be suitably used for growing plants such as sunny lettuce, radish sprouts, spinach, Japanese mustard greens, bok choy, bekana, strawberries, asparagus, etc. It can also be suitably used for hydroponic cultivation in closed plant factories, particularly for non-circulating thin film retention hydroponic cultivation.

[0051] Furthermore, by using reusable materials for the tray and cover, and using compostable biodegradable materials for the culture medium instead of materials that become industrial waste like rock wool, waste is reduced and soil and ocean pollution caused by waste dumping is curbed, thereby reducing the environmental burden. As a result, the system meets the following of the 17 goals and 169 targets set out in the international goals SDGs (Sustainable Development Goals) adopted at the United Nations Summit in September 2015: "8. Decent work and economic growth", "8.4 By 2030, improve progressively global resource efficiency in consumption and production and endeavour to decouple economic growth from environmental degradation, in accordance with the 10-year framework of programmes on sustainable consumption and production, with developed countries taking the lead." "9. Build resilient infrastructure, promote inclusive and sustainable development, and promote sustainable development through the sustainable use of natural resources and the promotion of sustainable development strategies.", "9.4 By 2030, improve infrastructure and retrofit industries, including by increasing resource-use efficiency and expanding the adoption of clean and environmentally friendly technologies and industrial processes, to make them sustainable. All countries will take action in accordance with their respective capabilities.", "11. Sustainable cities and communities", "11.6 By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management", - This technology contributes to the following goals: "12. Responsible Consumption and Production", "12.4 By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water and soil in order to minimize their adverse impacts on human health and the environment", and "12.5 By 2030, substantially reduce waste generation through prevention, reduction, recycling and reuse". [Explanation of symbols]

[0052] 100, 200... Hydroponic cultivation equipment 10...Tray section 11...Nutrient solution storage space 20, 20B...Cover part 21...first edge 22…Second edge 23…Third edge 24…Fourth edge 26...Opening 27...Through hole 28...Margin area 29...Arrow 30...Pot section 32...Slit 40...Culture medium LQ: nutrient solution PL…Plant LS…Light source NZ...liquid supply nozzle D1…first distance D2…Second distance D3: Third distance D4…Fourth distance EA…effective area

Claims

1. A tray portion having an open top surface to form a nutrient solution storage space for storing nutrient solution and having a rectangular shape in a plan view; a plate-shaped cover portion formed to a size that closes the nutrient solution storage space, the cover portion having a plurality of openings formed therein into which pot portions having plant seedlings planted therein are inserted and held; A hydroponic cultivation device comprising: The cover portion has the openings arranged in a checkerboard pattern, and a first distance from a first longitudinal edge to the opening closest to the first edge is longer than a second distance from a second longitudinal edge to the opening closest to the second edge.

2. The hydroponic cultivation device according to claim 1, A hydroponic cultivation device, wherein the first distance is greater than the width of the opening.

3. The hydroponic cultivation device according to claim 1, The hydroponic cultivation device, wherein the first distance is 1.5 times or more the second distance.

4. The hydroponic cultivation device according to claim 1, The cover portion has a rectangular shape in a plan view. One of the short sides is the first edge, The other of the short sides is the second edge, One of the long sides is the third edge, The other long side is the fourth edge, a third distance from the third edge to an opening closest to the third edge; and a fourth distance from the fourth edge to an opening closest to the fourth edge; A hydroponic cultivation device having a distance equal to the second distance.

5. The hydroponic cultivation device according to claim 1, At least the upper surface of the cover portion has a light-shielding property.

6. The hydroponic cultivation device according to claim 1, The cover portion of the hydroponic cultivation device is made of a black plate material.

7. The hydroponic cultivation apparatus according to claim 1, further comprising: The pot portion is formed in a pot shape with an open top, and is inserted into the opening of the tray portion with a plant seedling planted in the pot, and has a bottom surface protruding into the nutrient solution storage space, The pot portion has a slit formed from its bottom surface to its side surface, The hydroponics device is configured such that the nutrient solution storage space is filled with nutrient solution, and the nutrient solution is supplied to the plants in the pots through the slits while the bottom surface is immersed in the nutrient solution.

8. The hydroponic cultivation apparatus according to claim 6, The hydroponic cultivation device is configured such that the culture medium for growing plants contained in the pot of the pot portion is made of a compostable biodegradable material.

9. The hydroponic cultivation apparatus according to any one of claims 1 to 7, The cover part has through holes partially opened therein.

10. A plant cultivation method using a hydroponic cultivation device, A step of storing nutrient solution in the nutrient solution storage space of a tray portion having an open top surface and formed in a rectangular shape in a plan view; a step of placing a plate-shaped cover portion formed to a size that closes the nutrient solution storage space on the upper surface of the tray portion to close it; a step of inserting pot sections with plant seedlings planted in each of a plurality of openings formed in a grid pattern on the cover section, the plurality of openings being arranged so that a first distance from a first longitudinal edge of the cover section to the opening closest to the first edge is longer than a second distance from a second longitudinal edge to the opening closest to the second edge, and allowing the bottom of each pot section to be soaked in nutrient solution; When either the nutrient solution or the nutrients contained in the nutrient solution becomes insufficient, sliding the cover portion so as to partially open the nutrient solution storage space on the second end edge side in the longitudinal direction of the cover portion; A step of supplying nutrient solution from the partially opened nutrient solution storage space; A method for growing plants comprising the steps of:

11. The plant cultivation method according to claim 10, further comprising: The plant growing method comprises a step of removing the plant seedlings planted in the pot from the opening before they grow to commercial size and shipping them.

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