Hydroponic cultivation equipment

Abstract

This invention provides a configuration that allows for the irradiation of hydroponically grown plants with light in the red wavelength range, which is effective for their growth, without suppressing transpiration. [Solution] The hydroponic cultivation device 20, which reflects illumination light toward the cultivated plants, comprises a pair of reflective members 21a and 21b whose reflective surface is a sheet material 32 containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range. Both reflective members 21a and 21b are provided with ventilation holes 33 that connect the cultivation space, which is covered by the reflective members 21a and 21b, to the outside space.

Description

Technical Field

[0001] The present invention relates to a hydroponic cultivation tool used in a hydroponic cultivation device for hydroponically cultivating crops.

Background Art

[0002] Among sunlight, irradiation light from light-emitting elements (LEDs), etc., one of the wavelengths of light particularly effective for plant growth is considered to be in the red wavelength region (around 660 nm). For example, in the agricultural crop cultivation materials disclosed in Patent Document 1 below and the agricultural light-reflecting sheet disclosed in Patent Document 2 below, regarding open-field cultivation and forcing cultivation of vegetables in outdoor fields or greenhouses, a transmissive film, net, etc. containing a fluorescent substance that absorbs light in the ultraviolet region of sunlight and converts it into the red wavelength region necessary for plant growth is adopted, thereby improving plant growth. Also, regarding plant growth in hydroponic cultivation (fully artificial light type plant factory) that uses light-emitting elements without using soil or sunlight, for example, in the plant growth light source device disclosed in Patent Document 3 below, the emission luminance of a light-emitting element that emits red light and a light-emitting element that emits blue light are individually adjusted to promote plant growth.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, while hydroponics based on entirely artificial light has the advantage of being able to cultivate plants stably regardless of weather conditions, it also presents problems with initial costs such as lighting sources and control equipment, as well as running costs such as electricity consumption. In hydroponics, light in the red wavelength range contributes to improved growth, but methods that utilize fluorescence, where light is converted to the red wavelength range when transmitted through a transparent film containing fluorescent substances, have the problem that the irradiation efficiency decreases due to transmission. Furthermore, depending on the location where the transparent film is installed, airflow within the cultivation space may be obstructed, which can suppress transpiration of the cultivated plants.

[0005] The present invention was made to solve the above-mentioned problems, and its objective is to provide a configuration that can irradiate hydroponically grown plants with light in the red wavelength range that is effective for growth without suppressing transpiration of the plants. [Means for solving the problem]

[0006] To achieve the above objective, one embodiment of the present invention is: A hydroponic cultivation device (20, 20a) that reflects illumination light irradiated from a light source (13) of a hydroponic cultivation apparatus (1) toward the cultivated plants, The device comprises reflective members (21a, 21b, 22a, 22b) containing a fluorescent material that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range, The reflective member is characterized by being provided with a ventilation opening (33) that connects the cultivation space, where the cultivated plants are covered, with the external space using the reflective member.

[0007] Another embodiment of the present invention is, A hydroponic device (20b) that reflects illumination light irradiated from a light source (13) of a hydroponic cultivation apparatus (1) toward the cultivated plants, The device includes reflective members (23a, 23b) containing a fluorescent material that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range, The reflective member is characterized in that its lower end (34) is bent toward the cultivation space, with respect to the cultivation space over which the cultivated plants are covered using the reflective member. The symbols within the parentheses above indicate the correspondence with the specific means described in the embodiments described later. [Effects of the Invention]

[0008] In the present invention, a hydroponic cultivation device that reflects illumination light toward the cultivated plants comprises a reflective member containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range, and this reflective member is provided with a ventilation opening that connects the cultivation space, which is covered by the cultivated plants, with the outside space using the reflective member.

[0009] As a result, the light reflected from the reflective material toward the cultivated plants contains a large amount of light in the red wavelength range (light with a wavelength of around 660 nm), allowing for the irradiation of hydroponically grown plants with red wavelength light that is effective for their growth. In particular, since the reflective material is provided with vents that connect the cultivation space and the outside space, the humidity and temperature differences between the inside and outside spaces do not become excessively large, and the transpiration of the cultivated plants is not suppressed. Therefore, it is possible to realize a hydroponic cultivation device that can irradiate hydroponically grown plants with red wavelength light that is effective for their growth without suppressing the transpiration of the plants.

[0010] In this invention, a hydroponic cultivation device that reflects illumination light toward the cultivated plants comprises a reflective member containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range, and this reflective member is formed by bending its lower end toward the cultivation space, with respect to the cultivation space that covers the cultivated plants using the reflective member.

[0011] Even in this manner, the light reflected from the reflective member toward the cultivated plants contains a large amount of light in the red wavelength range, so that the hydroponically grown plants can be illuminated by reflection with light in the red wavelength range that is effective for growth. In particular, since the reflective member is formed by bending its lower end toward the cultivation space, the light reflected from the lower end is more likely to be illuminated toward the cultivated plants from diagonally below, so that the red wavelength range light can be more suitably irradiated toward the cultivated plants.

[0012] The reflective surface of the reflective material may be colored red. This makes it easier to amplify the red wavelength light reflected by the reflective material, thereby further improving the growth of cultivated plants.

[0013] The reflective members may be provided in pairs, facing each other along the longitudinal direction of the cultivation space. This allows light in the red wavelength range to be reflected onto the cultivated plants from both sides in the short direction of the cultivation space. Compared to the case where light in the red wavelength range is reflected from only one side in the short direction of the cultivation space, this allows for more favorable irradiation of the cultivated plants with light in the red wavelength range.

[0014] The reflective member may be formed by bending its lower end toward the cultivation space. This makes it easier for the light reflected at the lower end to irradiate the cultivated plants from an oblique downward angle, thus allowing for more favorable irradiation of the plants with light in the red wavelength range.

[0015] The lower end is formed by bending it with respect to the lower edge of the vent, and the reflective member may have an extended piece that extends diagonally upward from the lower edge toward the external space. This makes it possible to suppress the decrease in the amount of light reflected in the red wavelength region caused by the presence of the vent, by having at least a portion of the leaked light reflected into the cultivation space by the extended piece that functions as a reflective surface.

[0016] The lower end portion is formed by bending with reference to the upper edge of the ventilation port, and the reflecting member may include an extending piece that extends downward from the upper edge to the external space side. Thereby, even when the illumination light from the light source leaks into the external space through the ventilation port, at least a part of the leaked light is reflected into the cultivation space by the extending piece that functions as a reflecting surface, so that the decrease in the amount of light reflected in the red wavelength region due to the provision of the ventilation port can be suppressed.

[0017] The reflecting member may include a sheet material containing a fluorescent substance and a foamed resin plate to which the sheet material is attached to the cultivation object side. Thereby, since the foamed resin plate functions as a reinforcing plate with reduced weight, the reflecting member is not swayed by the wind, and the disturbance of the air flow in the cultivation space can be suppressed.

[0018] The reflecting member may be formed by applying a fluorescent paint obtained by containing a fluorescent substance in a solvent to a base material. For example, the reflecting member can be formed by applying the fluorescent paint to the base material by printing. Thereby, not only can the reflecting member be mass-produced at low cost, but also since the fluorescent paint can be formed into a thick film on the base material, a reflecting member excellent in color development (fluorescent action), hiding power (light shielding property), and weather resistance can be easily formed. In particular, by formulating the fluorescent paint so as to contain a plurality of types of fluorescent substances in a solvent, the fluorescent effect by the application of the fluorescent paint can be easily controlled according to the distribution of each fluorescent substance.

[0019] The reflecting member may be formed by applying the fluorescent paint to a foamed resin plate serving as a base material by screen printing. Thereby, since the amount (coating amount) of the fluorescent paint containing the fluorescent substance can be easily controlled according to the diameter of the holes of the screen printing, the amount of light reflected in the red wavelength region, etc., that is, the fluorescent effect of the present invention can be easily controlled.

Brief Description of the Drawings

[0020] [Figure 1] It is an explanatory diagram showing a hydroponic cultivation device including the hydroponic cultivation tool according to the first embodiment. [Figure 2] It is a side view of the hydroponic cultivation device of FIG. 1. [Figure 3] It is an enlarged view showing the vicinity of the ventilation hole in FIG. 1. [Figure 4] It is an enlarged view of the vicinity of the ventilation hole in FIG. 3 as viewed from the side of the foamed resin plate. [Figure 5] It is a graph measuring the reflectance of various sheets. [Figure 6] It is a graph of the radiation light spectrum measured on the planting board when various sheets are used as the reflecting surface of the reflecting member for partitioning the cultivation space and when there is no reflecting surface. [Figure 7] It is a graph showing the average value and standard deviation value of the plant weight of the cultivated plants grown for a predetermined period when various sheets are used as the reflecting surface of the reflecting member for partitioning the cultivation space and when there is no reflecting member in the first embodiment. [Figure 8] It is a graph measuring the humidity transition in the cultivation space with and without a ventilation hole together with the external humidity transition. [Figure 9] It is an explanatory view showing a hydroponic cultivation device provided with a hydroponic cultivation tool in the second embodiment. [Figure 10] It is an enlarged view showing the vicinity of the ventilation hole in FIG. 9. <000011​​​​​​​​​​​​​​​​​​​This graph shows the average and standard deviation values ​​of the plant weight of cultivated plants grown for a predetermined period of time in the third embodiment, with and without ventilation holes and with a lower end slope. [Figure 18] This graph compares the reflectance measurements when fluorescent paint is applied by screen printing and when a sheet material is attached. [Figure 19] This is an explanatory diagram showing an example of a fluorescent material with an emission peak around 660 nm. [Figure 20] This graph illustrates how reflectance changes depending on the combination of multiple types of fluorescent substances. [Modes for carrying out the invention]

[0021] [First Embodiment] Hereinafter, a first embodiment of a hydroponic cultivation apparatus equipped with the hydroponic cultivation tools according to the present invention will be described with reference to the drawings. The hydroponic cultivation apparatus 1 according to this embodiment is a fully artificial light type apparatus that hydroponically cultivates plants using light-emitting elements without using soil or sunlight. The apparatus is constructed by arranging hydroponic shelves 10 in multiple tiers vertically using a frame 2, with a lighting source 13 consisting of LEDs or the like arranged on a top plate 12 above the planting plate 11 and a hydroponic cultivation tank 14 arranged below it.

[0022] In this embodiment, as shown in Figures 1 and 2, the hydroponic cultivation apparatus 1 is configured with three hydroponic cultivation shelves 10 arranged vertically using a frame 2, and a blower 3 is installed for each hydroponic cultivation shelf 10 to blow air in the longitudinal direction of the hydroponic cultivation shelf 10 (left-right direction in Figure 2). The hydroponic cultivation shelf 10 is configured such that nutrient solution that promotes the growth of cultivated plants is stored in a hydroponic cultivation tank 14 and circulated using a pump or the like (not shown). Hereinafter, the left-right direction in Figure 1 will be referred to as the x-direction, the direction perpendicular to the plane of Figure 1 (left-right direction in Figure 2) as the y-direction, and the up-down direction in Figure 1 as the z-direction.

[0023] In addition to the planting plate 11, top plate 12, lighting source 13, and hydroponic cultivation tank 14 described above, the hydroponic cultivation rack 10 is equipped with a hydroponic cultivation device 20 that reflects the lighting light emitted from the lighting source 13 from the side toward the cultivated plants.

[0024] The hydroponic cultivation device 20 according to this embodiment includes a pair of left and right reflective members 21a and 21b that, together with the planting plate 11 and the top plate 12, constitute a cultivation space over which the cultivated plants are covered. Both reflective members 21a and 21b are symmetrical in shape and are arranged opposite each other along the longitudinal direction of the cultivation space. In this embodiment, a space with a width (length in the x-direction) W of approximately 700 mm and a height (length in the z-direction) H of approximately 500 mm is used as the cultivation space, and the height H of the cultivation space is determined by the height of both reflective members 21a and 21b (distance between the planting plate 11 and the top plate 12). The total length of the cultivation space (length in the y-direction) is determined by the number of reflective plates arranged, which will be described later. Both reflective members 21a and 21b are arranged using a frame 2 or the like so that their upper ends are connected to the top plate 12 and their lower ends are connected to the planting plate 11. However, they are not limited to this arrangement, and may be arranged so that a gap is formed between the upper end and the top plate 12, or so that a gap is formed between the lower end and the planting plate 11.

[0025] As shown in Figure 3, the reflective member 21a is constructed by arranging multiple reflective plates, each consisting of a roughly thin foamed resin plate 31 with a sheet material 32 attached to the side facing the cultivated plant, in a continuous line along the longitudinal direction. In this embodiment, for example, a 5 mm thick "Miraboard" manufactured by JSP Co., Ltd. is used as the foamed resin plate 31.

[0026] The sheet material 32 functions as a reflective surface that reflects the illumination light from the illumination light source 13 toward the cultivated plants. It contains a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range (around 660 nm), and is configured so that the reflective surface is colored red (for example, red). In this embodiment, for example, Nakagawa Chemical Co., Ltd.'s "Cutting Sheet 901K" in the red color is used as the sheet material 32, but it is not limited to this, and other sheet materials containing a fluorescent substance that can absorb light in the wavelength range of 600 nm or less and emit light in the red wavelength range may be used.

[0027] As shown in Figures 2 and 4, the foamed resin plate 31 and sheet material 32 constituting the reflective member 21a are provided with multiple rectangular ventilation openings 33 that connect the cultivation space and the external space. Each ventilation opening 33 has a width Wo of approximately 200 mm, a height Ho of approximately 35 mm, and a pitch P of approximately 100 mm, and is formed at a position H1 (for example, approximately 100 mm) below the average height of the cultivated plants at harvest time, in accordance with the height of the plants at harvest time.

[0028] Similar to the reflective member 21a, the reflective member 21b is configured to have a reflective surface made of a sheet material 32 containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range, and to have multiple ventilation holes 33 formed therein.

[0029] The hydroponic cultivation device 20 according to this embodiment is characterized in that the reflective surfaces of the reflective members 21a and 21b are made of a sheet material 32 containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range (around 660 nm), and a plurality of ventilation holes 33 are formed in both reflective members 21a and 21b.

[0030] First, the effects of the characteristic configuration of this embodiment, in which a sheet material 32 containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range is used as the reflective surface, will be described in detail below.

[0031] Although light in the red wavelength range is particularly effective for growing cultivated plants, when using general LEDs or the like as the illumination light source 13, the method of utilizing the fluorescence effect, which converts the irradiated light to the red wavelength range when transmitted through a transparent film containing a fluorescent substance, suffers from reduced irradiation efficiency due to transmission.

[0032] Therefore, in this embodiment, assuming that reflected light, rather than transmitted light, is irradiated onto the cultivated plants, a sheet material 32 containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range is used as the reflective surface. In particular, in this embodiment, since the sheet material 32 is colored red, it is possible to amplify light in the red wavelength range through reflection.

[0033] Figure 5 is a graph showing the reflectance of various sheets measured with wavelength on the horizontal axis using the "Spectro1 Pro" compact spectrophotometer manufactured by VARIABLE. In Figure 5, the measurement results for the sheet material 32 used in this embodiment are shown by the solid line R1, the measurement results for Yupo sheet (registered trademark), which is commonly used as a reflective material in hydroponics, are shown by the dashed line R2, and the measurement results for general expanded polystyrene material are shown by the dashed line R3.

[0034] As can be seen from Figure 5, with respect to reflection in the red wavelength region (around 660 nm), the reflectivity of the Yupo sheet and the expanded polystyrene material hardly changes, while the reflectivity of the sheet material 32 increases. This increase in reflectivity in the red wavelength region indicates that the sheet material 32 functions to amplify light in the red wavelength region through reflection.

[0035] Figure 6 is a graph of synchrotron radiation spectra measured on the planting board 11 using a Konica Minolta CL-70F spectroradiometer, comparing the cases where various sheets were used as reflective surfaces for cultivation space partitions and where there were no reflective surfaces. In Figure 6, the measurement results for the sheet material 32 used in this embodiment are shown by a solid line S1, the measurement results for the Yupo sheet are shown by a dashed line S2, and the measurement results when no reflective material is provided are shown by a dashed line S3.

[0036] As can be seen from Figure 6, in the red wavelength region (around 660 nm), the irradiance is highest with sheet material 32, while the irradiance with Yupo sheet is lower than with sheet material 32, and the irradiance is lowest when no reflective material is provided. As mentioned above, this is because sheet material 32 functions to amplify light in the red wavelength region through reflection, and by using sheet material 32 as the reflective surface, it is possible to efficiently irradiate hydroponically grown plants with light in the red wavelength region that is effective for their growth.

[0037] Figure 7 is a graph showing the average and standard deviation values ​​of plant weights of cultivated plants grown for a predetermined period in this embodiment, under the cases where various sheets are used as reflective surfaces for cultivation space partitions and where no reflective material is used. In Figure 7, for the cultivation of six leaf lettuce plants, the results are shown for cultivation without reflective material, cultivation with Yupo sheets, and cultivation with the sheet material 32 used in this embodiment without ventilation holes 33. The error bars in Figure 7 show the standard deviation values ​​for all six plants.

[0038] As can be seen from Figure 7, growth was fastest when using sheet material 32, slower with Yupo sheet than with sheet material 32, and slowest when no reflective material was provided. This indicates that the reflected light, which is amplified in the red wavelength region by reflection from sheet material 32, effectively contributes to the growth of the cultivated plants.

[0039] Next, the effects of the characteristic configuration of this embodiment, in which multiple ventilation holes 33 are formed in both reflective members 21a and 21b, will be described in detail below. Figure 8 is a graph showing the humidity changes within the cultivation space, measured using the "Ondotori" thermometer / hygrometer manufactured by T&D Co., Ltd., both with and without ventilation openings, along with the changes in humidity outside the cultivation space (external humidity). The measurement conditions were that the illumination light source 13 was lit for 22 hours, and the cultivation environment was air-conditioned to within the range of 20°C ± 3°C. In Figure 8, the measurement period (growing period) was set to one month, which is a guideline for the harvest time. The measurement results when ventilation openings 33 are formed in the reflective members 21a and 21b are shown with the symbol H1, the measurement results when ventilation openings 33 are not formed in the reflective members 21a and 21b are shown with the symbol H2, and the measurement results for external humidity are shown with the symbol H3.

[0040] As can be seen from Figure 8, the humidity change with and without the vents 33 in both reflective members 21a and 21b is almost the same at 2-3% until the growing season, but the difference increases to about 10% as the harvest season approaches. In the cultivation space without vents 33, the cultivated plants (leaf lettuce) grow larger and occupy a larger proportion of the cultivation space, making it easier for air to stagnate. In contrast, in the cultivation space with vents 33, even if the cultivated plants grow larger, air stagnation is suppressed. Therefore, as the harvest season approaches, the humidity measured in the cultivation space without vents 33 (see symbol H2 in Figure 8) is higher than the humidity measured in the cultivation space with vents 33 (see symbol H1 in Figure 8), and the difference with the external humidity (see symbol H3 in Figure 8) also increases. Regarding temperature differences, the measurement results showed a tendency for the temperature measured in the cultivation space without the ventilation holes 33 to have a larger difference from the external temperature compared to the temperature measured in the cultivation space with the ventilation holes 33.

[0041] Since transpiration of cultivated plants increases when the humidity around the leaves is low, forming vents 33 on both reflective members 21a and 21b suppresses the rise in humidity caused by air stagnation in the cultivation space compared to when vents 33 are not formed on both reflective members 21a and 21b, thereby promoting transpiration of cultivated plants.

[0042] Furthermore, regarding physiological disorders (tip burn) in cultivated plants, during the above-mentioned growing period, when the vents 33 were formed in the reflective members 21a and 21b, physiological disorders occurred in 2 out of 12 plants, while when the vents 33 were not formed in the reflective members 21a and 21b, physiological disorders occurred in 5 out of 12 plants. This indicates that the vents 33 provided in the reflective members 21a and 21b promote transpiration of cultivated plants and suppress physiological disorders.

[0043] As described above, the hydroponic cultivation device 20 according to this embodiment includes a pair of reflective members 21a and 21b whose reflective surface is a sheet material 32 containing a fluorescent substance that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range. Both reflective members 21a and 21b are provided with ventilation holes 33 that connect the cultivation space, which is covered with the cultivated plants, to the outside space using the reflective members 21a and 21b.

[0044] As a result, the light reflected from the sheet material 32, which serves as the reflective surface of both reflective members 21a and 21b, toward the cultivated plants contains a large amount of light in the red wavelength range (light with a wavelength of around 660 nm). Therefore, it is possible to irradiate hydroponically grown plants with red wavelength light that is effective for their growth through reflection. In particular, since both reflective members 21a and 21b are provided with vents 33 that connect the cultivation space and the external space, the humidity and temperature differences between the inside and outside of the cultivation space do not become excessively large, and the transpiration of the cultivated plants is not suppressed. Therefore, it is possible to realize a hydroponic cultivation device 20 that can irradiate hydroponically grown plants with red wavelength light that is effective for their growth without suppressing the transpiration of the cultivated plants.

[0045] Furthermore, in this embodiment, since the sheet material 32 that forms the reflective surface of both reflective members 21a and 21b is colored red, the light in the red wavelength range reflected by both reflective members 21a and 21b is easily amplified, thereby further improving the growth of cultivated crops.

[0046] Furthermore, in this embodiment, both reflective members 21a and 21b are provided as a pair facing each other along the longitudinal direction of the cultivation space. This allows light in the red wavelength range to be reflected onto the cultivated plants from both sides in the short direction (x direction) of the cultivation space. Compared to the case where light in the red wavelength range is reflected from one side in the short direction of the cultivation space (when only one of the reflective members 21a or 21b is used), light in the red wavelength range can be irradiated onto the cultivated plants more favorably. Depending on the cultivation environment, only one of the reflective members 21a or 21b may be used as the hydroponic cultivation device 20.

[0047] Furthermore, in this embodiment, both reflective members 21a and 21b are configured to include a sheet material 32 containing a fluorescent substance and a foamed resin plate 31 to which the sheet material 32 is attached to the cultivated plant side. As a result, the foamed resin plate 31 functions as a lightweight reinforcing plate, so that both reflective members 21a and 21b do not flap in the wind, and turbulence of airflow within the cultivation space can be suppressed.

[0048] [Second Embodiment] Next, the hydroponic cultivation equipment according to this second embodiment will be described with reference to the drawings. In this second embodiment, the main difference from the first embodiment is that the lower ends of both reflective members are bent toward the cultivation space. Therefore, components that are substantially the same as those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0049] As shown in Figure 9, the hydroponic cultivation device 20a according to this embodiment differs from the hydroponic cultivation device 20 described above in that it is configured with reflective members 22a and 22b instead of reflective members 21a and 21b.

[0050] As shown in Figures 10 and 11, the reflective member 22a is formed so that its lower end slopes downward by bending its lower end 34 toward the cultivated plant, using the lower edge 33a of the foamed resin board 31 to which the sheet material 32 is attached as a reference. In this embodiment, after making cuts in the sheet material 32 and foamed resin board 31 in the areas corresponding to the upper edge 33b and side edges 33c, 33d of the vent 33, the vent 33 is formed by bending the lower end 34 toward the cultivated plant, using the lower edge 33a as a reference, to create a downward slope. Therefore, the area surrounded by the aforementioned cuts becomes an extended piece 35 that extends diagonally upward from the lower edge 33a toward the external space when the lower end 34 is bent toward the cultivated plant.

[0051] Similar to the reflective member 22a, the reflective member 22b is also formed with a downward slope at its lower end 34 so that it can be bent toward the cultivated plant, and an extension piece 35 extends diagonally upward toward the external space from the lower edge 33a of the vent 33.

[0052] In this way, by bending the lower ends 34 of both reflective members 22a and 22b toward the cultivated plant, as shown in Figure 10, the light reflected by the lower ends 34 is more easily irradiated onto the cultivated plant from diagonally below. In particular, the extended piece 35 that extends diagonally upward toward the external space from the lower edge 33a reflects some of the light that has passed through the vent 33 toward the cultivation space. As a result, the cultivated plant can be irradiated with light in the red wavelength region by reflection over a wider area.

[0053] Figure 12 is a chart showing the irradiance at 660 nm measured on the planting plate 11 corresponding to the position of the cultivated plants, at different irradiation angles (measurement angles), using a Konica Minolta CL-70F spectroradiometer. Figure 12 illustrates the measurement results for each measurement angle, showing the rate of improvement in irradiance with and without a lower end inclination, compared to the area between the two reflective members 22a and 22b on the planting plate 11 and the area near reflective member 22b. The measurement angles correspond to irradiation from directly above (0°), irradiation from diagonally above (45°), irradiation from directly to the side (90°), and irradiation from diagonally below (135°).

[0054] As can be seen from Figure 12, in the middle section, the irradiance improves at each measurement angle except for the measurement at 0° (measurement from direct overhead), which is less affected by reflection, and in the vicinity section, the irradiance improves particularly at 90° and 135°. This indicates that the inclined lower ends of the reflective members 22a and 22b allow the reflected light from the sheet material 32 to be efficiently irradiated onto the cultivated plants.

[0055] Figure 13 is a graph showing the average and standard deviation values ​​of the plant weight of cultivated crops grown for a predetermined period in this embodiment, with and without vents 33 and a lower end slope on the reflective members 22a and 22b. In Figure 13, six leaf lettuce plants are grown, and the results are shown for cultivation with reflective members without vents and a lower end slope, and cultivation with reflective members 22a and 22b used in this embodiment (cultivation results with reflective members with vents and a lower end slope). The error bars in Figure 13 represent the standard deviation values ​​for all six plants.

[0056] As can be seen from Figure 13, by using reflective members 22a and 22b with vents 33 and a downward slope, the average plant weight of cultivated plants is greater than when reflective members without vents and a downward slope are used. This indicates that the vents 33 and the downward slope have an effective effect on the growth of cultivated plants. However, since the cultivation environment etc. in the cultivation test in which the test results in Figure 13 were obtained is different from the cultivation environment etc. in the cultivation test in which the test results in Figure 7 were obtained, the two test results cannot be simply compared.

[0057] As described above, in the hydroponic cultivation tool 20a according to this embodiment, the reflective members 22a and 22b are formed to have ventilation holes 33 and their lower ends 34 are bent toward the cultivated plant so that their lower ends are sloped.

[0058] As a result, the light reflected by the lower ends 34 of both reflective members 22a and 22b is more likely to be irradiated onto the cultivated plants from an oblique downward angle, thus allowing for more favorable irradiation of the cultivated plants with light in the red wavelength range.

[0059] In particular, the lower end portion 34 is formed by bending it with respect to the lower edge 33a of the ventilation opening 33, and both reflective members 22a and 22b are formed to have an extended piece 35 that extends diagonally upward from the lower edge 33a toward the external space.

[0060] As a result, even if the illumination light from the light source 13 leaks into the external space through the vent 33, at least a portion of the leaked light is reflected back into the cultivation space by the extension piece 35 which functions as a reflective surface, thereby suppressing the decrease in the amount of light reflected in the red wavelength region caused by the provision of the vent 33.

[0061] As a modified example of this embodiment, as illustrated in Figure 14, the reflective member 22a may be formed by bending its lower end portion 34 toward the cultivated plant with reference to the upper edge 33b of the vent 33, so that the portion surrounded by cuts made in the parts corresponding to the lower edge 33a and side edges 33c, 33d of the vent 33 becomes an extended piece 35 that extends downward toward the external space from the upper edge 33b. The same applies to the reflective member 22b.

[0062] Even in this manner, when illumination light from the illumination light source 13 leaks into the external space through the ventilation holes 33, at least a portion of the leaked light is reflected back into the cultivation space by the extension piece 35 which functions as a reflective surface, thereby suppressing the decrease in the amount of light reflected in the red wavelength region caused by the provision of the ventilation holes 33.

[0063] [Third Embodiment] Next, the hydroponic cultivation equipment according to this third embodiment will be described with reference to the drawings. In this third embodiment, the main difference from the second embodiment and the like is that the ventilation holes in the sloping lower end of the reflective member have been eliminated. Therefore, components that are substantially the same as those in the second embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0064] As shown in Figure 15, the hydroponic cultivation device 20b according to this embodiment differs from the hydroponic cultivation device 20a described above in that reflective members 23a and 23b are used instead of reflective members 22a and 22b.

[0065] As shown in Figure 16, the reflective member 23a is formed without the ventilation holes 33 compared to the reflective member 22a. Similarly, the reflective member 23b is formed without the ventilation holes 33 compared to the reflective member 22b.

[0066] Even with the hydroponic cultivation device 20b configured in such a way as to eliminate the ventilation opening 33, the light reflected by the lower ends 34 of both reflective members 23a and 23b is more likely to be irradiated onto the cultivated plants from an oblique downward angle, thus allowing for more favorable irradiation of the cultivated plants with light in the red wavelength range.

[0067] Figure 17 is a graph showing the average and standard deviation values ​​of the plant weight of cultivated plants grown for a predetermined period in this embodiment, under two conditions: when there is no ventilation opening but a lower end slope is provided, and when there is a ventilation opening but no lower end slope. In Figure 17, the results of growing six leaf lettuce plants are shown for each condition, using the reflective members 23a and 23b adopted in this embodiment (results with no ventilation opening but with a lower end slope) and the results with a ventilation opening but no lower end slope (results with a configuration corresponding to the first embodiment). The error bars in Figure 17 represent the standard deviation values ​​for all six plants.

[0068] As can be seen from Figure 17, the average plant weight and standard deviation of the cultivated plants are almost the same for the cultivation results with no vents but with a sloping bottom and the cultivation results with vents but no sloping bottom. Therefore, by using reflective members 23a and 23b with sloping bottoms, the same cultivation effect as reflective members 21a and 21b, which form vents 33, can be obtained. Note that the cultivation environment etc. in the cultivation test in which the test results in Figure 17 were obtained is different from the cultivation environment etc. in the cultivation test in which the test results in Figure 7 were obtained and the cultivation environment etc. in the cultivation test in which the test results in Figure 13 were obtained, so the results of each test cannot be simply compared.

[0069] The present invention is not limited to the embodiments described above, and may be further embodied as follows, for example. (1) The reflective members 21a and 21b are not limited to being formed by attaching the sheet material 32 to the foamed resin board 31 or the like to create a base member (hereinafter also referred to as a reflective base member) before the ventilation holes 33 are provided. For example, the reflective base member may be formed by applying a fluorescent paint containing the above-mentioned fluorescent substance in a solvent or the like to the base material such as the foamed resin board 31. The same applies to the other reflective members 22a and 22b, etc.

[0070] For example, the reflective base member can be formed by applying the fluorescent paint to the foamed resin board 31 by printing. This not only allows for low-cost mass production of the reflective base member, but also enables the application of the fluorescent paint as a thick film on a substrate such as the foamed resin board 31, making it easy to form a reflective base member with excellent color development (fluorescence), opacity (light shielding), and weather resistance.

[0071] Specifically, for example, the reflective base member may be formed by applying the above-mentioned fluorescent paint to the foamed resin plate 31, which serves as the base material, by stencil printing (screen printing). This allows for easy control of the amount of fluorescent paint containing the fluorescent substance (application amount) according to the diameter of the holes in the stencil printing, thereby easily controlling the amount of light reflected in the red wavelength region, i.e., the fluorescence effect of the present invention.

[0072] Therefore, in a reflective base member formed by applying the above-mentioned fluorescent paint to a substrate such as a foamed resin board 31 by screen printing, increasing the thickness of the coating makes it possible to increase the reflectivity in the red wavelength region (around 660 nm) compared to the sheet material 32 bonding configuration (see measurement result R1), as can be seen from measurement result R4 in Figure 18.

[0073] Even when using other printing methods such as relief printing (letterpress printing, flexographic printing), lithographic printing (offset printing), or intaglio printing (gravure printing) instead of the aforementioned stencil printing, the amount of fluorescent paint (coating amount) can be easily controlled, and therefore the fluorescent effect can be easily controlled, just as with stencil printing.

[0074] In particular, by formulating a fluorescent paint containing multiple types of fluorescent substances in a solvent, the fluorescent effect of applying the fluorescent paint can be easily controlled according to the proportion of each fluorescent substance. Fluorescent substances are broadly classified into organic fluorescent substances, inorganic fluorescent substances, and hybrid fluorescent substances that combine the characteristics of both. For the applications of this invention, since light conversion efficiency, light shielding properties, light resistance, and durability are required, it is desirable to use inorganic fluorescent substances. Inorganic fluorescent substances are further classified into oxide-based, sulfide-based, nitride-based, halide-based, and silicate-based types, and each fluorescent substance has a different emission color range. As illustrated in Figure 19, there are single fluorescent substances that have an emission peak around 660 nm, but they have characteristics that make them unsuitable for the applications of this invention, such as low light resistance, so it is necessary to appropriately select a combination of each fluorescent substance according to the applications of this invention.

[0075] For example, by adding another fluorescent substance that emits light in the wavelength range near 660 nm to the solvent of a fluorescent paint whose measurement result is indicated by symbol R4 in Figure 18, the reflectance can be controlled so that the emission peak is near 660 nm, as exemplified by symbol R5 in Figure 20.

[0076] Furthermore, since blue wavelengths (400-500 nm, especially 450 nm) are also effective for plant growth, by adding a fluorescent substance that emits light in the above blue wavelength range to the fluorescent paint whose measurement result is indicated by symbol R4 in Figure 18, a reflectance as exemplified by the dashed line R6 in Figure 20 can be obtained, thereby further improving the growth effect on cultivated plants.

[0077] (2) The sheet material 32 is not limited to being colored with red as a reddish color, but may also be colored with pink as a reddish color, for example.

[0078] (3) The reflective member for reflecting the illumination light from the side toward the cultivated plants is not limited to being configured by attaching a sheet material 32 to the cultivated plant side of the foamed resin plate 31 as described above, but may also be configured as, for example, a foamed resin plate in which the fluorescent substance is kneaded into the resin.

[0079] (4) The reflective member for reflecting illumination light from the side toward the cultivated plants is not limited to being constructed by attaching the sheet material 32 to the cultivated plant side of the foamed resin plate 31 as described above, but may also be constructed by attaching the sheet material 32 to the cultivated plant side of a plate made of a different material from the foamed resin plate 31 as a reinforcing plate. Alternatively, the sheet material 32 may be used as the reflective member without employing a reinforcing plate such as the foamed resin plate 31. In this case, the sheet material 32 may be held in a windable state by a winding machine or the like. This makes it possible to easily perform harvesting work by winding up the sheet material 32 when harvesting the cultivated plants.

[0080] (5) The hydroponic shelves 10 are not limited to being arranged vertically in three tiers using the frame 2, but may also be made up of one tier, or two or four or more tiers arranged vertically, depending on the cultivation environment, etc.

[0081] (6) The lighting source 13 is not limited to LEDs, which are commonly used in fully artificial light hydroponics; for example, fluorescent lamps or light bulbs may also be used.

[0082] (7) The vent 33 is not limited to being formed to open in a rectangular shape, but may also be formed to open in a circular, elliptical, or polygonal shape, for example.

[0083] (8) The sheet material 32 may be provided not only in pairs facing each other along the longitudinal direction of the cultivation space, but also, for example, on the installation surface (ceiling surface) of the lighting source 13.

[0084] (9) The sheet material 32 may be configured to be folded in multiple places, for example, depending on the height and size of the plant, the shape of the hydroponic cultivation device 1, rather than just folding one place of the lower end 34 toward the plant. [Explanation of Symbols]

[0085] 1 Hydroponic cultivation system 10 hydroponic shelves 11 Planting board 13 Lighting source 20, 20a, 20b Hydroponic cultivation equipment 21a, 21b, 22a, 22b, 23a, 23b Reflective material 31 Foamed resin board 32 Sheet material 33 Ventilation holes 34 Lower end 35 Extension piece

Claims

1. A hydroponic cultivation device that reflects illumination light emitted from a light source of a hydroponic cultivation apparatus toward the cultivated plants, The device includes a reflective member containing a fluorescent material that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range. A hydroponic cultivation device characterized in that the reflective member is provided with a ventilation opening that connects the cultivation space, over which the cultivated plants are covered, with the external space using the reflective member.

2. A hydroponic cultivation device that reflects illumination light emitted from a light source of a hydroponic cultivation apparatus toward the cultivated plants, The device includes a reflective member containing a fluorescent material that absorbs light in the wavelength range of 600 nm or less and emits light in the red wavelength range. The hydroponic cultivation device is characterized in that the reflective member is formed by bending its lower end toward the cultivation space, with respect to the cultivation space over which the cultivated plants are covered using the reflective member.

3. The hydroponic cultivation device according to claim 1 or 2, characterized in that the reflective surface of the reflective member is colored in a reddish color.

4. The hydroponic cultivation device according to claim 1 or 2, characterized in that the reflective members are provided in pairs facing each other along the longitudinal direction of the cultivation space.

5. The hydroponic cultivation tool according to claim 1, characterized in that the reflective member is formed by bending its lower end toward the cultivation space.

6. The lower end is formed by bending it with respect to the lower edge of the ventilation opening, The hydroponic cultivation device according to claim 5, characterized in that the reflective member comprises an extended piece that extends diagonally upward from the lower edge toward the external space.

7. The lower end is formed by bending it with respect to the upper edge of the ventilation opening, The hydroponic cultivation device according to claim 5, characterized in that the reflective member comprises an extended piece extending downward from the upper edge toward the external space.

8. The hydroponic cultivation device according to claim 1 or 2, characterized in that the reflective member comprises a sheet material containing the fluorescent substance and a foamed resin plate to which the sheet material is attached to the cultivated plant side.

9. The hydroponic cultivation tool according to claim 1 or 2, characterized in that the reflective member is formed by applying a fluorescent paint containing the fluorescent substance in a solvent to a substrate.

10. The hydroponic cultivation tool according to claim 9, characterized in that the reflective member is formed by applying the fluorescent paint to the substrate by printing.

11. The hydroponic cultivation tool according to claim 9, characterized in that the reflective member is formed by applying the fluorescent paint to the foamed resin plate which serves as the base material by stencil printing.

Images