Culture medium sheet

Abstract

To provide a medium sheet for plant cultivation that allows for optimal growth of plants and offers superior handleability.SOLUTION: A medium sheet 1 according to the present invention includes a plurality of first parts 11 that are designated sown areas and positioned apart from each other, and a second part 12 that is composed of the same material as that of the plurality of first parts 11 and has a greater bulk density than that of the plurality of first parts 11. In the medium sheet 1, the second part 12 is disposed adjacent to each of the plurality of first parts 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a culture medium sheet for plant cultivation. [Background technology]

[0002] When cultivating plants, water-absorbent foams, fibers, etc. are sometimes used as culture medium materials. In particular, urethane sponges and the like are widely used because they can easily retain the water and air necessary for plant growth and therefore can be excellent culture mediums (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-320298 Summary of the Invention [Problem to be solved by the invention]

[0004] A culture medium made of urethane sponge can be used for hydroponic cultivation, for example, by sowing seeds in multiple locations in the culture medium and then immersing it in a nutrient solution, etc. However, conventional culture mediums made of urethane sponge have been difficult to handle, for example, because they have no parts that can be gripped or supported, making them difficult to hold. On the other hand, it is possible to use a sheet-shaped medium (medium sheet) as the culture medium. In this case, it is required to ensure the ease of handling of the medium sheet and to be able to properly cultivate plants in multiple cultivation areas provided on the medium sheet.

[0005] The present invention has been made in view of the above circumstances, and aims to achieve the following objects. The present invention aims to solve the above-mentioned problems of the prior art and to provide a culture medium sheet for plant cultivation that allows plants to grow appropriately and is easy to handle. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the culture medium sheet of the present invention has a plurality of first parts that are arranged at positions separated from each other as parts to be sown, and a second part that is made of the same material as the plurality of first parts and has a bulk density greater than that of the plurality of first parts, and is characterized in that in the culture medium sheet, the second part is arranged adjacent to each of the plurality of first parts. The culture medium sheet of the present invention has a first portion and a second portion with different bulk densities, and in the first portion with a lower bulk density, seeds can easily grow roots after sowing, allowing plants to be cultivated appropriately. On the other hand, the second portion with a higher bulk density can be gripped when holding the culture medium sheet, or can be used to support the culture medium sheet. This results in a culture medium sheet for plant cultivation that allows plants to grow appropriately and is easy to handle.

[0007] Furthermore, it is preferable that the second part surrounds each of the multiple first parts and is arranged in a continuous state with each of the multiple first parts on the culture medium sheet. In the above configuration, the second section, which has a high bulk density, surrounds each of the multiple first sections, which have a low bulk density, making it easier to grasp or support the peripheral portion of each first section, and thus providing a culture medium sheet that is easier to handle.

[0008] Furthermore, it is preferable that each of the plurality of first portions has an exposed surface that is exposed on both sides in the thickness direction of the culture medium sheet. In the above configuration, the first part, which has a low bulk density, is provided in a state where it penetrates the culture medium sheet, so that root growth is not hindered, and thus a culture medium sheet with superior plant growth characteristics is provided.

[0009] It is also preferable that each of the plurality of first portions has a recess for sowing seeds on an exposed surface at one end side in the thickness direction. In the above configuration, the depressions allow for stable seeding, providing a medium sheet that is easier to handle.

[0010] Preferably, each of the first portions has a through hole extending along the thickness direction from an exposed surface on one end side in the thickness direction to an exposed surface on the other end side. In the above configuration, the through-holes stabilize root growth, providing a medium sheet with better plant growth properties.

[0011] The material preferably contains a biodegradable resin. With the above configuration, after cultivation, the culture medium can be disposed of together with the roots of the plants planted in the culture medium and reused as fertilizer, thereby providing a culture medium sheet that is easier to handle.

[0012] In addition, it is preferable that the middle position of each of the plurality of first portions and the middle position of the second portion are different from each other in the thickness direction of the culture medium sheet. With the above configuration, when the culture medium sheet is used for hydroponic cultivation, the culture medium sheet can be positioned in a position that makes it less likely for the second part to be immersed in water, thereby preventing the culture medium sheet from tearing and providing a culture medium sheet that is easier to handle.

[0013] In addition, the second portion preferably has a protrusion that protrudes in the thickness direction of the culture medium sheet. In the above configuration, the rigidity of the culture medium sheet is increased and bending within the sheet is suppressed, thereby providing a culture medium sheet that is easier to handle.

[0014] The second portion preferably has a bent portion. In the above configuration, the rigidity of the culture medium sheet is increased and bending within the sheet is suppressed, thereby providing a culture medium sheet that is easier to handle.

[0015] It is also preferable that the thickness of each of the plurality of first portions is greater than the thickness of the second portion. With the above configuration, the culture medium sheet can be easily grasped or supported, and therefore a culture medium sheet with better handling properties is provided. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a culture medium sheet for plant cultivation that allows plants to grow appropriately and is easy to handle. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing an example in which the culture medium sheet according to the first embodiment of the present invention is applied to a hydroponic cultivation device, and is a diagram showing a cross section of the hydroponic cultivation device. [Figure 2] FIG. 1 is a perspective view of a culture medium sheet according to a first embodiment of the present invention. [Figure 3A] FIG. 2 is a plan view showing one of the multiple regions included in the culture medium sheet according to the first embodiment of the present invention. [Figure 3B] FIG. 2 is a side view showing one of the multiple regions included in the culture medium sheet according to the first embodiment of the present invention. [Figure 3C] FIG. 2 is a bottom view showing one of the multiple regions included in the culture medium sheet according to the first embodiment of the present invention. [Figure 4] FIG. 3B is a cross-sectional view showing a cross section II of FIG. 3A. [Figure 5] FIG. 10 is a perspective view of a culture medium sheet according to a modified example of the first embodiment of the present invention. [Figure 6] FIG. 1 is a perspective view of a conventional culture medium sheet. [Figure 7] FIG. 1 is a plan view showing one of the multiple regions included in a conventional culture medium sheet. [Figure 8] FIG. 8 is a cross-sectional view showing the II-II cross section of FIG. 7. [Figure 9] FIG. 10 is a perspective view of a culture medium sheet according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing one of the multiple regions included in a culture medium sheet according to another embodiment of the present invention. [Figure 11] FIG. 2 is a cross-sectional view (part 2) showing one of a plurality of regions included in a culture medium sheet according to another embodiment of the present invention. [Figure 12] FIG. 10 is a bottom perspective view showing one of the multiple regions included in a culture medium sheet according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] A culture medium sheet according to one embodiment of the present invention will be described in detail below with reference to a preferred embodiment shown in the accompanying drawings. In the following, the culture medium sheet according to the present invention will be described using a culture medium sheet that can be used for hydroponic cultivation as a representative example, as shown in Figure 1. However, the present invention is not limited to this case, and as long as the culture medium sheet can be used for plant cultivation, it may be used for any cultivation method, for example, a culture medium sheet for soil cultivation.

[0019] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Furthermore, in this specification, unless otherwise specified, a state in which the bulk density is high will also be referred to as "hard" for convenience, and a state in which the bulk density is low will also be referred to as "soft" for convenience. In addition, in this specification, the term "bulk density" is calculated by dividing the mass of a substance by the total volume (external volume) of the substance, including the solid portion of the substance and the voids inside the substance, and is the mass per total volume (volume defined by the external shape) of the substance, and its unit is [g / cm 3 The bulk density can be measured by a known method.

[0020] Furthermore, in this specification, unless otherwise specified, when describing the shape of a sheet-like member, the direction from one main surface of the member to the other main surface will be referred to as the "thickness direction" for convenience. Furthermore, in this specification, unless otherwise specified, the terms "match" and "same" may include a range of error generally accepted in the technical field to which the present invention belongs. In addition, unless otherwise specified, the position and state of each part of the culture medium sheet will be described assuming that the culture medium sheet is in use. In this specification, the side of the culture medium sheet that is irradiated with light, i.e., the side toward which the plant stems grow, will be referred to as the "upper side" for convenience. On the other hand, the side of the culture medium sheet that faces the surface of the nutrient solution or that is immersed in the nutrient solution, i.e., the side toward which the plant roots grow, will be referred to as the "lower side" for convenience.

[0021] [Cultivation device with culture medium sheets] A hydroponic cultivation device including a culture medium sheet (hereinafter, culture medium sheet 1) according to one embodiment of the present invention will be described. The culture medium sheet 1 of the present invention is used in a hydroponic cultivation device for hydroponic cultivation, as shown in Figure 1. As shown in Figure 1, the hydroponic cultivation device has the culture medium sheet 1, a container 2, and a support rod 3. Note that the up-down direction in Figure 1 indicates the vertical direction, and the left-right direction in Figure 1 indicates the horizontal direction.

[0022] As shown in Figure 2, the culture medium sheet 1 is a sheet-like member configured by regularly arranging a plurality of square regions 10 on its surface. After seeds are sown in each region 10 in the culture medium sheet 1, the lower part of each region 10 is immersed in a nutrient solution 4 stored in a deep tray-shaped container 2, whereby the seeds germinate in each region 10, and plants grow, yielding plant seedlings. In other words, in hydroponic cultivation, the culture medium sheet 1 (strictly speaking, the first part 11 described below) functions to relay the supply of the nutrient solution 4 containing water and nutrients to the plants while growing the plants.

[0023] As described above, the culture medium sheet 1 is supported in the container 2 at a position where the lower part of the culture medium sheet 1 is immersed in the nutrient solution 4. More specifically, as shown in FIG. 1, a plurality of support rods 3 extending vertically upward are provided at the bottom of the container 2. Each of the plurality of support rods 3 is inserted into a support rod hole 123 formed in the culture medium sheet 1 (more specifically, the second part 12 described below), thereby supporting the culture medium sheet 1 by the support rods 3. It is preferable that the shape of the support rods 3 be tapered so that the diameter gradually increases toward the lower end.

[0024] <<First Embodiment>> A first embodiment of the present invention will be described below with reference to Figures 1 to 8. As described above, the culture medium sheet 1 according to the first embodiment is used in a hydroponic cultivation device for hydroponic cultivation, as shown in Figure 1.

[0025] First, the basic structure of a culture medium sheet 1 according to a first embodiment will be described with reference to FIGS. As shown in FIG. 2, the culture medium sheet 1 has a plurality of regions 10. In the culture medium sheet 1, each of the plurality of regions 10 is arranged regularly on the surface, and the regions 10 abut each other and are connected to form a single sheet. The outer edge of the culture medium sheet 1 has a rectangular shape in a plan view. The culture medium sheet 1 may be in a sheet form, and the shape of its outer edge is not particularly limited and may be a shape other than a rectangle. For example, the outer edge of the culture medium sheet 1 may be a square, triangle, hexagon, or other polygonal shape or a shape including a curved line other than a rectangle, and may be designed appropriately depending on the cultivation environment, etc. Furthermore, the culture medium sheet 1 may be used by being unwound as appropriate from a rolled state.

[0026] As shown in Figures 3A to 3C and 4, each of the multiple regions 10 has a first portion 11 with a low bulk density and a second portion 12 with a high bulk density. Each of the multiple regions 10 is configured such that the second portion 12 is arranged to surround the entire periphery of the first portion 11. The boundary between the first portion 11 and the second portion 12 and the boundary between the regions 10 each form a square. These two square-shaped boundary lines are arranged so as to be parallel to each other, as shown in Figure 3A. Therefore, when the culture medium sheet 1 is viewed in a plane, the first portions 11 of the multiple regions 10 are arranged in a floating island-like manner, regularly spaced apart. Furthermore, it is sufficient that multiple first parts 11 are arranged at regular intervals, and the shapes of the boundary lines between the first parts 11 and the second parts 12, as well as the boundary lines between the regions 10, are not particularly limited and may be shapes other than squares. For example, the shapes of the boundary lines between the first parts 11 and the second parts 12, as well as the boundary lines between the regions 10, may be figures including quadrilaterals, triangles, hexagons, other polygons, and curves other than squares, and may be designed appropriately according to the cultivation environment, etc. Also, for example, the boundary lines between the first parts 11 and the second parts 12, as well as the boundary lines between the regions 10, do not have to be parallel to each other.

[0027] When using the culture medium sheet 1, as shown in Figure 1, in each of the multiple regions 10, seeds are sown on the upper surface of the first section 11, which is less bulky and softer, and the plants are grown in the first section 11. After germination, the plant roots grow through the inside of the first section 11 and downwards from the first section 11, and the plant stems and leaves (i.e., above-ground parts) grow upwards from the first section 11. Also, when using the culture medium sheet 1, as shown in Figure 1, one plant is grown in each of the multiple regions 10. In other words, the same number of plants as the number of regions 10 can be cultivated on the culture medium sheet 1. Note that, as long as the culture medium sheet 1 is stably supported, the number of plants grown in each first section 11 is not limited to one, and multiple plants may be grown.

[0028] Furthermore, when using the culture medium sheet 1, the culture medium sheet 1 is supported by the second part 12, which has a higher bulk density and is harder, as shown in Figure 1. Specifically, with the culture medium sheet 1 placed inside the container 2, a support rod hole 123 is formed in the second part 12 in the part directly above the support rod 3, and the culture medium sheet 1 is supported inside the container 2 by inserting the support rod 3 into this support rod hole 123.

[0029] Then, when the plants have grown to a predetermined stage on the culture medium sheet 1, the multiple regions 10 on the culture medium sheet 1 are separated from each other. Here, it is preferable that perforations or cut lines are formed along the boundaries between the regions 10 so that each region 10 can be easily separated. The separated individual regions 10 then function as a single culture medium and are moved to a larger cultivation space where plant cultivation continues.

[0030] Next, a detailed configuration of the first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, each of the multiple first parts 11 and the second part 12 are molded from the same material and are continuously connected in the culture medium sheet 1. Specifically, since the first parts 11 and the second parts 12 are molded by processing a single component (sheet material) that forms the base material of the culture medium sheet 1, they are connected seamlessly as a continuous body. In other words, although the bulk density of each of the multiple first parts 11 and the material of the second part 12 differ, they are composed of a single component, i.e., the same sheet material.

[0031] Furthermore, in the first embodiment, as shown in Figures 1, 3B, and 4, the lower end of the first part 11 and the second part 12 of each of the multiple regions 10 are molded so that the lower end of the first part 11 is located below the lower end of the second part 12. In other words, when viewing the entire culture medium sheet 1 from the bottom side (immersion side), the multiple first parts 11, which are regularly spaced apart, protrude downward from the second parts 12 surrounding the first parts 11. To put it another way, a step is formed between the first parts 11 and the second parts 12 on the bottom side of the culture medium sheet 1, and each of the multiple first parts 11 is regularly arranged on the bottom surface of the culture medium sheet 1 as a portion that protrudes downward.

[0032] Similarly, as shown in Figures 1, 3B, and 4, the first part 11 and second part 12 of each of the multiple regions 10 are molded such that the upper end of the first part 11 is positioned above the upper end of the second part 12. In other words, when viewing the entire culture medium sheet 1 from the top side (sowing side), the multiple first parts 11, which are arranged at regular intervals, protrude more than the second parts 12 surrounding the first parts 11. To put it another way, a step is formed between the first parts 11 and the second parts 12 on the top side of the culture medium sheet 1, and each of the multiple first parts 11 is regularly arranged on the top surface of the culture medium sheet 1 as an upwardly protruding portion.

[0033] Furthermore, as shown in Figures 3B and 34, it is preferable that the intermediate positions of each of the multiple first parts 11 and the intermediate positions of the second part 12 are different in the thickness direction of the culture medium sheet 1. Moreover, it is even more preferable that the intermediate positions of each of the multiple first parts 11 are located lower than the intermediate positions of the second part 12 in the thickness direction of the culture medium sheet 1. Note that the intermediate position refers to the intermediate position between one end face (upper end face) and the other end face (lower end face) of the first part 11 and the second part 12, respectively.

[0034] The material constituting the first part 11 and the second part 12 of the culture medium sheet 1 according to the first embodiment is the same material, and more specifically, it is preferably a water-absorbent fibrous natural material. Water-absorbent fibrous materials have water permeability and breathability, and are capable of retaining moisture and air inside, making them suitable for plant cultivation. Furthermore, natural materials are superior in terms of ease of disposal and reuse as fertilizer such as compost. The natural material constituting the culture medium sheet 1 is preferably a material containing biodegradable resin, and may contain, for example, at least one of pulp and rayon.

[0035] The method for molding the culture medium sheet 1 is compression molding, in which the culture medium sheet 1 is molded by compressing the second part 12 of a single material. Specifically, the material for the culture medium sheet 1 (sheet material) is sandwiched between two plates, each having multiple regularly spaced holes, and the sheet material is compressed at a predetermined pressure. As a result, the portion of the sheet material that is not compressed and has entered the holes becomes the first part 11, and the portion compressed between the plates becomes the second part 12. The second part 12 only needs to be molded to have a higher bulk density than the sheet material, and the molding method is not limited to compression molding. For example, the second part 12 may be molded to have a higher bulk density by using a hardening agent or thermal shrinkage. Conversely, as a molding method, the portion of the sheet material corresponding to the first part 11 may be treated to reduce its bulk density.

[0036] Next, several parts of Part 11 will be explained in more detail with reference to Figures 1, 2, 3A-C and 4. In the culture medium sheet 1 according to the first embodiment, each of the plurality of first portions 11 is adjacent to a second portion 12, as shown in Figures 2 and 3A to 3C. More specifically, in the culture medium sheet 1, it is preferable that each of the plurality of first portions 11 is arranged in a state where its entire periphery is surrounded by the second portion 12, as shown in Figures 3A and 3C. Furthermore, in the culture medium sheet 1 according to the first embodiment, each of the multiple first parts 11 is provided so as to be exposed on both sides of the culture medium sheet 1, as shown in Figures 3A-C and 4. In other words, in the thickness direction of the culture medium sheet 1, one end face (upper end face) and the other end face (lower end face) of each first part 11 are both exposed surfaces, or in other words, each first part 11 penetrates the culture medium sheet 1.

[0037] Furthermore, as shown in Figures 3A, 3B, and 4, a recessed depression 111 for sowing seeds is preferably provided on the upper end surface of each first part 11. In this case, the size of the opening of the depression 111 is preferably slightly larger than the seed to be sown. When sowing seeds on the upper end surface of each first part 11, it is also preferable to attach a fixing member to fix the sown seeds to the first part 11. As the fixing member, it is more preferable to use a material made by dispersing a water-absorbing powder such as fine pulp in water and then drying it, or a material made by coating it with an aqueous solution of a water-soluble resin such as PVA (Polyvinyl alcohol) and then drying it. It is even more preferable that the fixing member is made by mixing pulp and biomaterials such as cellulose. The shape of the depression 111 is not particularly limited, and for example, it may be a slit-shaped cut with a depth sufficient to hold the seed. The orientation of the slit-shaped cut is not particularly limited, but a cross-shaped or H-shaped cut is preferable because the planting method can be changed depending on the size and number of seeds.

[0038] Furthermore, each of the multiple first sections 11 may be provided with multiple through-holes 112 extending from the upper end surface to the lower end surface of the first section 11 along the thickness direction of the culture medium sheet 1, as shown in Figures 3C and 4. This allows the roots of the plants grown in the first section 11 to grow through each through-hole 112 toward the lower end surface of the first section 11, and to grow further below the lower end surface of the first section 11. It is preferable that the size of the opening of each through-hole 112 is slightly larger than the diameter of a single root of the plant being cultivated.

[0039] If the bulk density of each of the plurality of first portions 11 is too small, the shape will be distorted in the nutrient solution 4, and conversely, if it is too large, the growth of plant roots will be inhibited. Therefore, the bulk density value of each of the first portions 11 is set to 0.01 to 1.00 [g / cm 3 ], and 0.05 to 0.50 [g / cm 3 ], and more preferably 0.10 to 0.40 [g / cm 3 It is particularly preferred that

[0040] Next, Part 2, Section 12 will be explained in more detail with reference to Figures 1, 2, 3A-C, 4, and 5. As described above, the second part 12 is made of the same material as the multiple first parts 11 and is a part that is denser and harder than the culture medium sheet 1. Furthermore, in the thickness direction of the culture medium sheet 1, the length (thickness) of the second part 12 should be smaller than the length (thickness) of each of the multiple first parts 11, as shown in Figures 1, 3B, and 4.

[0041] In the first embodiment, the second part 12 may have the same number of support rod holes 123 as the support rods 3, as shown in Figures 2, 3A, and 3C. The support rod holes 123 are formed, for example, near the four corners of a square region 10, with a size that allows the support rods 3 to pass through. Note that the configuration for supporting the culture medium sheet 1 is not limited to a configuration in which the support rods 3 are inserted into the support rod holes 123 to support the culture medium sheet 1, and other support structures may be used.

[0042] Furthermore, in the first embodiment, the second part 12 is provided with rib-shaped protrusions 121 that project in the thickness direction of the culture medium sheet 1, as shown in Figures 1 and 2. The provision of these protrusions 121 improves the rigidity of the culture medium sheet 1, and as a result, the occurrence of deflection of the culture medium sheet 1 during use can be suppressed. The rib-shaped protrusions 121 may extend relatively long along the boundary lines between regions 10 on the culture medium sheet 1 and may be arranged in a square grid pattern as shown in Figure 2. However, the position, extension direction, and extension length of the protrusions 121 are not particularly limited and can be determined arbitrarily. Furthermore, as shown in Figure 5, the second part 12 may be provided with a bent portion 122 in the thickness direction, either instead of or together with the convex portion 121. The bent portion 122 may have a sawtooth-like shape, or a wavy (arc-shaped) curved shape, as shown in Figure 5.

[0043] The bulk density of Part 2 12 is important; if it's too small, it won't hold the culture medium sheet 1, and if it's too large, it will be difficult to mold. Therefore, the bulk density of Part 2 12 should be between 0.50 and 3.00 [g / cm³]. 3], and 0.80 to 2.00 [g / cm 3 ], and more preferably 1.00 to 1.80 [g / cm 3 It is particularly preferred that

[0044] [Effects of the culture medium sheet according to the first embodiment of the present invention] The effects obtained by the culture medium sheet 1 according to the first embodiment will be described with reference to FIGS. The culture medium sheet 1 according to the first embodiment of the present invention allows plants to grow appropriately and is easy to handle.

[0045] Specifically, as shown in Figures 6, 7, and 8, a conventional urethane sponge medium sheet 1X has unmolded rectangular or cubic regions 10X arranged on its surface. In such a conventional urethane sponge medium sheet 1X, the bulk density of each part of the sheet is uniform and does not vary, and the bulk density is low and soft overall. Due to this configuration, it is difficult to secure a portion to grip or support the conventional urethane sponge medium sheet 1X, making it difficult to handle.

[0046] Furthermore, as described above, the conventional urethane sponge medium sheet 1X has a low bulk density and is soft. Therefore, when the conventional urethane sponge medium sheet 1X is pulled up or moved, there is a risk that the urethane sponge, which is the material of the sheet, may deform, lose its shape, or tear. Because of these properties, when plants are grown using the conventional urethane sponge medium sheet 1X, there is a risk that the deformation or tearing of the medium sheet 1X may unintentionally damage the plants.

[0047] On the other hand, if the size of the urethane sponge is increased in order to maintain its shape, the amount of urethane sponge consumed per seedling will increase, which is undesirable from both an environmental and economic perspective and is not suitable for large-scale plant cultivation. Furthermore, after cultivation of a plant, the roots are spread throughout the medium, and so the roots and the medium tend to be treated as a single entity. However, there are cases where the roots and the medium have different disposal and reuse methods. In such cases, although it is necessary to separate the roots from the medium, for the reasons mentioned above, it is difficult to separate the roots from the medium, and it is time-consuming to dispose of them or reuse them as fertilizer such as compost.

[0048] In contrast, in the culture medium sheet 1 according to the first embodiment, the multiple first portions 11 and the second portions 12 arranged around them are made of the same material and are molded with different bulk densities. The multiple first portions 11, which have a lower bulk density and are softer, are arranged regularly spaced apart, as shown in Figures 2 and 5, so that seeds can be sown in each first portion 11 and plants (germinated plants) can grow in each first portion 11. On the other hand, the second portions 12, which have a higher bulk density and are harder, are arranged so as to surround each of the multiple first portions 11, and the culture medium sheet 1 can be supported by the second portions 12.

[0049] The above-described configuration allows plants to grow appropriately in the first section 11, and the inclusion of the second section 12 realizes a culture medium sheet 1 for plant cultivation that is easy to handle. Furthermore, the arrangement of the first section 11 and the second section 12 allows multiple plants (i.e., plants cultivated in each first section 11) to grow in a state where they are evenly spaced apart on the culture medium sheet 1, so that the distance between the closest plants for each plant is maintained at a certain level. This reduces the risk that the above-ground parts of a plant will grow too long, hindering the growth of neighboring plants, and as a result, multiple plants can be cultivated stably at the same time.

[0050] Furthermore, the material (sheet material) of the culture medium sheet 1 of the first embodiment is a natural material containing at least one of pulp and rayon as a main component. Because this sheet material is primarily made of natural materials, when processing the culture medium together with the roots that have spread throughout the culture medium, the roots and the culture medium can be disposed of and reused together.

[0051] Furthermore, in the culture medium sheet 1 of the first embodiment, each of the multiple first parts 11 and the second part 12 are made of the same material and are molded in a continuous, connected state as a single sheet. This configuration makes it difficult to separate each of the multiple first parts 11 and the second part 12, and the entire culture medium sheet 1 can be supported by gripping or supporting the second part 12. Therefore, the culture medium sheet 1 is easier to handle than conventional products.

[0052] Furthermore, in the culture medium sheet 1 of the first embodiment, each of the multiple first parts 11 is molded so that both sides of the culture medium sheet 1 are exposed, as shown in Figures 3A-C and 4. With this configuration, as seeds sown on the upper surface of the culture medium sheet 1 germinate and plants grow, the plant roots can grow through the first parts 11 until they protrude from the lower surface of the first parts 11. Therefore, the culture medium sheet 1 is a good culture medium for plant cultivation.

[0053] Furthermore, in the culture medium sheet 1 of the first embodiment, as shown in Figures 1, 3B, and 4, the lower end of the first part 11 and the second part 12 of each of the multiple regions 10 are positioned lower than the lower end of the second part 12. With this configuration, when the lower surface of the culture medium sheet 1 is immersed in the nutrient solution 4 in the container 2, the lower parts of the multiple first parts 11 are immersed in the nutrient solution 4, but the second parts 12 do not come into contact with the nutrient solution 4 and are less likely to get wet. As a result, tearing of the second parts 12 due to wetting is suppressed, and the usable condition of the culture medium sheet 1 can be properly maintained.

[0054] Furthermore, in the culture medium sheet 1 of the first embodiment, each of the upper end surfaces of the multiple first parts 11 is provided with a depression 111 for sowing seeds, as shown in Figures 3A, 3B, and 4. It is preferable that this depression 111 be formed to be slightly larger than the size of the seed of the plant to be cultivated. By providing such depressions 111, the movement of the sown seeds is suppressed, and the seeds germinate and grow within the depressions 111. As a result, the plant is cultivated with a stable plant position in each first part 11.

[0055] Furthermore, in the culture medium sheet 1 of the first embodiment, each of the multiple first parts 11 is provided with multiple through holes 112, as shown in Figures 3C and 4. Each through hole 112 preferably penetrates from the upper end surface to the lower end surface of the first part 11. By providing such multiple through holes 112, the plant roots are guided by each through hole 112 and grow along a predetermined direction (the direction in which each through hole 112 is formed). As a result, the plant roots grow well in each first part 11, and the plants are cultivated more appropriately.

[0056] Furthermore, in the culture medium sheet 1 of the first embodiment, the second part 12 has at least one of a protruding portion 121 in the thickness direction of the culture medium sheet 1 and a curved portion 122 that is curved in an undulating manner in the thickness direction of the culture medium sheet 1, as shown in Figures 2 and 5. By providing such protruding portions 121 and curved portions 122 in the second part 12, the rigidity of the culture medium sheet 1 is improved, and as a result, the occurrence of deflection of the culture medium sheet 1 during use can be suppressed. This further improves the handling of the culture medium sheet 1 as a culture medium for plant cultivation.

[0057] <<Second Embodiment of the Invention>> In the culture medium sheet 1 according to the first embodiment described above, one seed is sown in each of the multiple first parts 11, but this is not limited to this. For example, as shown in Figure 9, multiple seeds may be sown in each of the multiple first parts 11A. A culture medium sheet 1A having each of the multiple first parts 11A with such a configuration will be described in detail below with reference to Figure 9 as the second embodiment. In the second embodiment, the basic configuration and usage method of the hydroponic cultivation apparatus are the same as in the first embodiment, but as shown in Figure 9, the shape of each of the multiple first parts 11A differs from that of the first embodiment. Specifically, in the second embodiment, the shape of each of the multiple regions 10A is a roughly rectangular shape that extends long in a predetermined direction, as shown in Figure 9. In addition, the shape of the first part 11A is also roughly rectangular to match the shape of each region 10A. Due to this shape, multiple seeds are sown in a row in each first part 11A. In this case, it is preferable that four or more seeds are sown. With this configuration, the area that can be sown on the culture medium sheet 1A (i.e., the area occupied by the multiple first parts 11A) becomes larger, and thus the amount of crops grown when using one culture medium sheet 1A, that is, the efficiency of cultivation, is improved.

[0058] <<Other embodiments relating to the present invention>> Although several embodiments of the culture medium sheet 1 of the present invention have been described above, these embodiments are merely examples to facilitate understanding of the present invention and do not limit it. In other words, the present invention can be modified and improved without departing from its spirit. Furthermore, it goes without saying that the present invention includes equivalents thereof.

[0059] The culture medium sheet of the present invention may have a plurality of first parts provided at a distance from each other, and a second part made of the same material as the plurality of first parts and having a greater bulk density than the plurality of first parts. Furthermore, the culture medium sheet of the present invention may have a shape other than that of the embodiments described above, as long as each of the plurality of first parts and the second part are arranged adjacent to each other. To explain in more detail, in the culture medium sheet 1 according to the first embodiment described above, the intermediate positions of the multiple first parts 11 and the second parts 12 are different in the thickness direction. However, it is not limited to this, and as shown in Figure 10, in the culture medium sheet 1B, the intermediate positions of each of the multiple first parts 11B and the intermediate positions of the second part 12B may overlap (may coincide) in the thickness direction.

[0060] Furthermore, in the culture medium sheet 1 according to the first embodiment described above, the positions of the upper surfaces in the thickness direction are different between the multiple first parts 11 and the second parts 12. However, it is not limited to this, and as shown in Figure 11, in the culture medium sheet 1C, the positions of the upper surfaces of the multiple first parts 11C and the positions of the upper surfaces of the second parts 12C may overlap (or coincide) in the thickness direction. With the above-described configuration, compared to the first embodiment, the lower end of each of the multiple first parts 11C is more likely to be positioned relatively lower than the lower end of the second part 12C. When a culture medium sheet 1C with such a configuration is used, the multiple first parts 11C are more easily immersed in the nutrient solution 4, while the second part 12C is less likely to get wet.

[0061] Furthermore, in the culture medium sheet 1 according to the first embodiment described above, a plurality of small diameter through-holes 112 are arranged at regular intervals. However, it is not limited to this, and as shown in Figure 12, the plurality of through-holes 112D in the culture medium sheet 1D may be formed to form long, straight slits. When a culture medium sheet 1D with such a configuration is used, plant roots can grow well through each through-hole 112D and easily pass through the inside of the through-holes. Figure 12 is a perspective view from the bottom of each of the plurality of regions 10D provided in the culture medium sheet 1D according to a modified example. [Explanation of symbols]

[0062] 1, 1A, 1B, 1C, 1D Medium Sheet 2 containers 3 Support rod 4. Nutrient solution 10, 10A, 10B, 10C, 10D regions (medium) 11, 11A, 11B, 11C, 11D Part 1 12, 12A, 12B, 12C, 12D Part 2 111 Depression 112 Through hole 113 Support material 121 Convex part 122 Bent section 123 Support rod hole

Claims

1. A medium sheet, a plurality of first portions provided at positions spaced apart from each other as portions to be sown; a second portion made of the same material as each of the plurality of first portions and having a bulk density greater than that of each of the plurality of first portions; In the culture medium sheet, the second part is arranged adjacent to each of the plurality of first parts, a thickness of each of the plurality of first portions is greater than a thickness of the second portion; a lower end of each of the plurality of first portions is located lower than a lower end of the second portion, A culture medium sheet, wherein the upper end of each of the plurality of first portions is positioned higher than the upper end of the second portion.

2. The culture medium sheet according to claim 1, wherein the second portion surrounds each of the plurality of first portions and is arranged in a continuous state with each of the plurality of first portions on the culture medium sheet.

3. The culture medium sheet according to claim 1 , wherein each of the plurality of first portions has an exposed surface that is exposed on both sides in the thickness direction of the culture medium sheet.

4. The culture medium sheet according to claim 3, wherein each of the plurality of first portions has a recess for sowing seeds on the exposed surface at one end side in the thickness direction.

5. The culture medium sheet of claim 4, wherein each of the plurality of first portions has a through hole extending along the thickness direction from the exposed surface at one end side in the thickness direction to the exposed surface at the other end side.

6. The culture medium sheet according to claim 1 , wherein the material comprises a biodegradable resin.

7. The culture medium sheet according to claim 1, wherein the intermediate position of each of the plurality of first portions and the intermediate position of the second portion are different from each other in the thickness direction of the culture medium sheet.

8. The culture medium sheet according to claim 1 , wherein the second portion has a convex portion that protrudes in the thickness direction of the culture medium sheet.

9. The medium sheet of claim 1 , wherein the second portion has a curved bend.

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