Plant cultivation device and plant cultivation method

Abstract

To avoid the saturation of photosynthesis efficiency of a plant and reduce the waste of light energy.SOLUTION: The plant cultivation device for growing a plant with artificial light includes a growing space 30 in which a plant 200 is grown and at least one light source panel 32 for irradiating the growing space with artificial light Li. The light source panel includes a substrate 33 and a plurality of light output units 34 arranged at intervals on the substrate. The photon flux density B (μmol m-2 s-1) of the artificial light emitted from one light output unit is less than or equal to the photosynthesis saturated light intensity L of a leaf of the plant.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a plant growing device and a plant growing method for growing plants using artificial light. [Background technology]

[0002] Plant factories are being considered as a way to increase agricultural production and achieve stable harvests. In plant factories, it is possible to control various parameters, such as the intensity of light for photosynthesis irradiated on crops from artificial light sources, environmental conditions such as temperature, humidity, carbon dioxide (CO2) concentration, and wind speed in the plant growth space, and fertilizer components for plant growth. This makes it possible to produce crops year-round, dramatically increasing crop productivity.

[0003] Patent Document 1 discloses a closed-type plant factory that cultivates plants by irradiating them with artificial light such as light from an LED (light emitting diode) light source without using sunlight. In this closed-type plant factory, light is irradiated closely from the side of the plant body, making it possible to cultivate vegetables that grow vertically and become tall, such as tomatoes and cucumbers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5330162 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to cultivate plants stably, it is desirable to supply them with a sufficient amount of light as evenly as possible. In order to apply light as evenly as possible, it is possible to increase the distance between the light source and the plant. However, this creates wasted space. Furthermore, as the distance increases, the light spreads and attenuates, resulting in a loss of energy. When using a light source with an LED chip, if the LED chip is placed too close to the plant, the photosynthetic efficiency may reach saturation, resulting in a waste of energy. Also, the heat emitted from the LED chip may damage the plant.

[0006] Therefore, the present invention provides a plant growing device and a plant growing method that avoids saturation of the photosynthetic efficiency of plants and reduces waste of light energy. [Means for solving the problem]

[0007] One aspect of the present invention provides a plant growing device for growing a plant with artificial light. The plant growing device has a growing space for growing the plant, and at least one light source panel for irradiating the growing space with artificial light. The light source panel has a substrate and a plurality of light output units arranged on the substrate at intervals. The photon flux density B (μmol m -2 ·s -1 ) is equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant.

[0008] In one aspect of the present invention, there is provided a method for cultivating a plant using artificial light. This plant cultivating method comprises irradiating a cultivation space in which the plant is cultivated with artificial light from at least one light source panel having a plurality of light output units arranged at intervals on a substrate. The photon flux density B (μmol m -2 ·s -1 ) is equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant. Effect of the Invention

[0009] In one embodiment of the present invention, the photon flux density B (μmol m -2 ·s -1) is equal to or less than the photosynthetic saturation light intensity L of the plant leaves, it is possible to avoid saturation of the photosynthetic efficiency of the plant and reduce waste of light energy. In this way, by preventing the emission of excessive light energy, it is possible to prevent damage to the plant due to heat radiation from the light output unit. Therefore, the light output unit can be placed close to the plant, which can minimize the spread and attenuation of light from the light output unit and reduce energy loss. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing a schematic configuration example of a plant growing device according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a perspective view of the plant cultivation device of FIG. 1. [Diagram 3] FIG. 2 is a front view of a light source panel of the plant growing device. [Figure 4] FIG. 4 is a vertical cross-sectional view of the light source panel of FIG. [Diagram 5] 1 is a graph showing the light-photosynthesis curve of soybean. [Figure 6] 1 is a table showing parameters of two manufacturing examples of a plant growing device according to an embodiment of the present invention. [Figure 7] 1 is a table showing parameters of two examples of plant cultivation devices used in tests to verify the effectiveness of embodiments of the present invention. [Figure 8] FIG. 11 is a vertical cross-sectional view of a light source panel according to a modified example of the embodiment of the present invention. [Figure 9] FIG. 11 is a vertical cross-sectional view of a light source panel according to another modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The drawings are not necessarily drawn to scale, and some features may be exaggerated or omitted.

[0012] The plant cultivation device according to the embodiment is arranged in a plant factory. A large number of plant cultivation devices are arranged in the plant factory, and each plant cultivation device can be called a cultivation unit. The plants to be cultivated are, for example, agricultural crops such as beans, but may also be other plants that perform photosynthesis.

[0013] As shown in Fig. 1, a plant factory in which a plant growing device 1 according to an embodiment is arranged is provided with an air conditioning system 20. The air conditioning system 20 adjusts the environment of an area in which plants are grown to temperature, humidity, and carbon dioxide (CO2) concentration suitable for growing plants.

[0014] As shown in Figures 1 and 2, the plant cultivation device 1 has an upper portion 10, a nutrient solution tank 12 arranged below the upper portion 10, and a support panel 14 attached to the upper end of the nutrient solution tank 12. The upper portion 10 has a cultivation space 30 in which the stems and leaves of a plant 200 grow (i.e., in which the plant is cultivated). The lower portion of the stem and roots (including the main root and lateral roots) of the plant 200 are arranged in the nutrient solution tank 12, where the roots grow. The support panel 14 supports the plant 200.

[0015] The nutrient solution tank 12 is a container into which a nutrient solution (liquid fertilizer) 16 is supplied and discharged to the roots of the plants 200. The supply and discharge of the nutrient solution 16 to the nutrient solution tank 12 is performed by a nutrient solution supply and discharge system 18 connected to the nutrient solution tank 12.

[0016] The upper part 10 of the plant cultivation device 1 has at least one light source panel 32 that irradiates the cultivation space 30 with artificial light Li. The light source panel 32 irradiates the plant 200 with artificial light Li from the side. In this embodiment, the upper part 10 includes two light source panels 32 that are oriented vertically and arranged parallel to each other. In this manner, the two light source panels 32 face each other, the cultivation space 30 is interposed between the two light source panels 32, and the two light source panels 32 irradiate the plant 200 with artificial light Li from both sides.

[0017] As shown in FIG. 2, the light source panel 32 has a height X that is greater than the upper limit of the growth height of the plants 200, and a width Y that is capable of applying artificial light Li almost evenly and sufficiently to the multiple plants 200 planted at intervals from one another. The interval Z between the two light source panels 32 is set large enough to allow the artificial light Li to be applied almost evenly and sufficiently to each leaf of the plant 200. The interval Z is also set large enough not to damage the plant 200 due to heat radiation from the light source panels 32. However, the interval Z is smaller than the quotient of the width Y divided by n+1 (n is the number of plants 200 in the cultivation space 30). Therefore, the interval Z is smaller than the width W of the light output area of ​​the light source panel 32 corresponding to one plant 200. The light output area is an area in which an LED chip, which will be described later, is mounted.

[0018] As shown in Figures 3 and 4, the light source panel 32 has a flat substrate 33 serving as a support, and a number of LED chips (light output units) 34 arranged on the substrate 33. These LED chips 34 are of the same type. Therefore, when the same current and voltage are applied, these LED chips 34 emit artificial light Li with the same photon flux density. The LED chips 34 are regularly arranged (specifically, in a matrix) at equal intervals vertically and horizontally.

[0019] The substrate 33 is provided with wiring (not shown) for lighting these LED chips 34. Outside the light source panel 32 or on the substrate 33, a control device (not shown) for simultaneously controlling the emission of light from these LED chips 34 is provided.

[0020] A plurality of ventilation holes 35 are formed in the substrate 33. The ventilation holes 35 are through-holes. Air managed by the air conditioning system 20 is supplied to the growing space 30 through these ventilation holes 35, and the plants 200 are prevented from being overheated by heat dissipation from the light source panel 32. The ventilation holes 35 have the same size and are regularly (specifically, in a matrix) arranged at equal intervals vertically and horizontally. However, the ventilation holes 35 may have different sizes or may be arranged irregularly. Other measures may be used to cool the light source panel 32 in addition to or instead of the ventilation holes 35. For example, a heat dissipation member, a water-cooling pipe, or an air-cooling pipe may be in contact with the surface of the substrate 33 opposite the LED chips 34.

[0021] In order to increase the efficiency of use of the artificial light Li in the cultivation space 30, it is preferable that the surface of the substrate 33 facing the LED chip 34 has a high light reflectance. The substrate 33 is preferably made of a light-reflecting material (e.g., a metal with a smooth surface). The surface of the substrate 33 facing the LED chip 34 may be coated with a light-reflecting paint.

[0022] 3 and 4 are merely examples. The size, number and spacing of the LED chips 34 are not limited to those shown in the drawings, and the size, number and spacing of the ventilation holes 35 are also not limited to those shown in the drawings.

[0023] In the plant cultivation device 1, the photon flux density B (μmol m -2 ·s -1 ) is preferably equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant 200. The photosynthetic saturation light intensity of the leaves is the light intensity at which the photosynthetic rate is maximized. In other words, the photosynthetic saturation light intensity is the light intensity at which the photosynthetic efficiency is saturated, and providing more light than this will not promote plant growth and will result in a waste of light energy.

[0024] The photosynthetic saturation light intensity of leaves is explained with reference to the light-photosynthesis curve of soybeans in Figure 5. In Figure 5, the horizontal axis is the PPFD (Photosynthetic Photon Flux Density), or light intensity, received by the leaves. The vertical axis is the amount of CO2 absorbed by photosynthesis or the photosynthetic rate, expressed as "μmol m -2 ·s -1 " units are shown.

[0025] Different types of plants have different light-photosynthesis curves.

[0026] As shown in Figure 5, the photosynthetic rate is low under weak light and high under strong light. However, when the light intensity exceeds a certain level, the photosynthetic rate (or the amount of absorbed CO2) does not exceed a certain level.

[0027] For soybeans, the PPFD is 400 μmol m -2 ·s -1 Below this, the photosynthetic rate is proportional to the PPFD, i.e., there is little energy loss. PPFD is 400-800 μmol m -2 ·s -1 In this case, although there is a certain amount of energy loss, as the PPFD increases, the photosynthetic rate also increases. For example, when the PPFD is 400 μmol m -2 ·s -1 to 800 μmol m -2 ·s -1 Even if the amount of nitrogen in the atmosphere increases by twofold, the rate of photosynthesis increases by only about 1.5-fold. PPFD is 800 μmol m -2 ·s -1 Above this level, the rate of photosynthesis slows down, resulting in a large energy loss. However, this does not have a negative effect on plant growth. For example, when the PPFD is 400 μmol m -2 ·s -1 to 1600 μmol m -2 ·s -1 Even if the temperature rises fourfold, the rate of photosynthesis increases only about 1.8-fold. PPFD is 2000 μmol m -2 ·s -1 When the PPFD exceeds 2000 μmol m, the photosynthetic rate of soybeans becomes constant. In other words, the photosynthetic efficiency of soybeans becomes saturated. -2 ·s -1 Above this level, there is a possibility that adverse effects may occur on plant growth. -2 ·s -1 This is because it is impossible for a PPFD to exceed this limit.

[0028] As described above, there is a light intensity L at which the photosynthetic efficiency of a plant is saturated, and the photon flux density B (μmol m-2 ·s -1 ) is equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant 200, it is possible to avoid saturation of the photosynthetic efficiency of the plant and reduce waste of light energy. In other words, it is preferable that B≦L.

[0029] In this way, damage to the plant 200 due to heat radiation from the LED chip 34 can be prevented by preventing the emission of excessive light energy. Therefore, the LED chip 34 can be disposed close to the plant 200, which can minimize the spread and attenuation of the artificial light Li from the LED chip 34 and reduce the loss of energy. For example, as described above with reference to FIG. 2, the interval Z can be made smaller than the width W of the light output area of ​​the light source panel 32 corresponding to one plant 200. By reducing the interval Z between the light source panels 32 in the plant cultivation device 1, it is possible to prevent the plant cultivation device 1 from becoming large.

[0030] As is clear from the above explanation, for soybeans, the leaf photosynthetic saturation intensity L is 2000 (μmol m -2 ·s -1 ) Therefore, if the photon flux density B of the artificial light Li emitted from one LED chip is 2000 μmol m -2 ·s -1 In this case, it is possible to avoid saturation of photosynthetic efficiency in soybeans and reduce waste of light energy.

[0031] On the other hand, if the intensity of the artificial light Li from the LED chips 34 is reduced, there is a concern that the photosynthetic efficiency will decrease, the growth of the plant will be inhibited, and the yield will decrease. In the plant cultivation device 1 according to this embodiment, the intensity of the artificial light Li emitted from one LED chip 34 is reduced, while the number of LED chips 34 is increased to supply a sufficient amount of light as uniformly as possible to a wide area of ​​the plant 200.

[0032] In this embodiment, the photon flux G (μmol m -3 ·s -1) is the photosynthetic compensation photon flux M (μmol m -3 ·s -1 ), that is, G>M.

[0033] The photosynthetic compensation photon flux M (μmol m) of 200 plants per unit volume in the growth space 30 -3 ·s -1 ) is the light compensation point H (μmol m -2 ·s -1 ) and the cumulative leaf area K (m 2 m -3 ) The light compensation point H is the light intensity at which the photosynthetic rate and the respiration rate are equal on the leaf surface of a plant; in other words, it is the minimum amount of energy required for the leaf to grow.

[0034] The integrated leaf area K in the growth space 30 is the sum of the leaf areas of the plants 200 in the growth space 30, and is calculated by the following formula. K=I*J / F where I is the Leaf Area Index (LAI) (m 2 m -2 ) The leaf area index I is the area per unit of land surface area (for example, 1 m 2 ) is the sum of the projected areas of all leaves above the growth space 30 (m 2 ) F is the volume of the growth space 30 (m 3 ).

[0035] Therefore, the photosynthetic compensation photon flux M is calculated from the following formula: M=H*K =H*I*J / F

[0036] Therefore, the photosynthetic compensation photon flux M of the plant 200 per unit volume in the growth space 30 is the minimum photon flux per unit volume required for all leaves of the plant 200 in the growth space 30 to grow.

[0037] The light compensation point H varies depending on the type of plant. The leaf area index I varies depending on the type of plant and its growth stage. For soybeans, the light compensation point H is approximately 50 μmol m -2 ·s -1 The leaf area index (I) of soybeans at the flowering stage and mid-grain filling stage is approximately 4.0.

[0038] Therefore, during the flowering and mid-grain filling stages of soybeans, the growth space 30 is 1 m 3 Assuming that the plant has a unit volume of 1 m (height, width, and depth are 1 m), the photosynthetic compensation photon flux M of the plant 200 per unit volume in the growth space 30 is 200 μmol m -3 ·s -1 Therefore, during the flowering and mid-grain filling stages of soybeans, the photon flux G per unit volume in the growth space 30 is 200 μmol m -3 ·s -1 In this case, the growth of soybean leaves in the growing space 30 can be promoted.

[0039] Photon flux G (μmol m -3 ·s -1 ) is calculated from the following formula: G=A*B*C / F Here, A is the light emitting area of ​​the artificial light Li per LED chip 34, i.e., the light output area (m 2 ·Pieces -1 ), and B is the photon flux density (μmol m -2 ·s -1 ), C is the number of LED chips 34 that emit artificial light Li into the growing space 30, and when two light source panels 32 are used, it is the total number of LED chips 34 in both light source panels 32. F is the volume (m 3 ).

[0040] Therefore, in order to promote the growth of the leaves of the plant 200 in the cultivation space 30, it is preferable to satisfy the following relationship. G=A×B×C / F>M

[0041] For soybeans, M is 200 μmol m -3 ·s -1 Therefore, A × B × C / F > 200 μmol m -3 ·s -1 This can promote leaf growth in the growing space 30.

[0042] As long as the above relationship is satisfied, the position of the light source panel 32 relative to the plant 200 and thus the cultivation space 30 is not limited. For example, the light source panel 32 may be disposed above the cultivation space 30 so that the light source panel 32 emits artificial light Li from above into the cultivation space 30.

[0043] However, in order to make the photon flux G per unit volume as uniform as possible in the growth space 30, the leaf area index I, that is, the density of the leaves, should be taken into consideration. When artificial light Li is emitted from above the growth space 30, at a growth stage when the plant 200 has many leaves, the artificial light Li is blocked by the upper leaves, and the photon flux G per unit volume becomes low in the lower part of the growth space 30.

[0044] Therefore, in this embodiment, the light source panel 32 is disposed on the side of the cultivation space 30 so that the light source panel 32 irradiates the plant 200 with artificial light Li from the side. Therefore, regardless of the growth stage of the plant 200, particularly the state of leaf growth, the photon flux G per unit volume can be made as uniform as possible between the upper and lower parts of the cultivation space 30.

[0045] The number of light source panels 32 may be one. However, in order to make the photon flux G per unit volume as uniform as possible on both sides of the plant 200, in this embodiment, as shown in Figures 1 and 2, two light source panels 32 face each other, the growth space 30 is interposed between the two light source panels 32, and the two light source panels 32 irradiate the plant 200 with artificial light Li from both sides. In this way, it is preferable to provide two light source panels 32, and in this case, the photon flux G per unit volume can be made as uniform as possible on both sides of the plant 200.

[0046] In addition to the two light source panels 32, two more light source panels 32 may be provided at both ends of the light source panels 32 in the longitudinal direction (the direction of width Y). That is, four light source panels 32 may be provided around the growth space 30, and the four light source panels 32 may emit artificial light Li into the growth space 30. However, in this case, the plant 200 arranged near the end of the growth space 30 in the longitudinal direction (the direction of width Y) receives more artificial light Li than the plant 200 arranged in the center of the longitudinal direction of the growth space 30. In this case, if the amount of artificial light Li emitted from each LED chip 34 is large, the leaves of the plant 200 arranged near the end of the longitudinal direction of the growth space 30 may receive light with an intensity higher than the photosynthetic saturation light intensity L, which may result in a waste of light energy. Therefore, it is preferable to provide only two light source panels 32 as in this embodiment.

[0047] FIG. 6 shows parameters of two example plant growing devices according to embodiments of the present invention. In both Examples 1 and 2, as shown in Figures 1 and 2, two light source panels 32 were arranged in parallel so that a growth space 30 was interposed between the two light source panels 32. In each light source panel 32, a substrate 33 was formed from aluminum, and a water-resistant film was formed on the surface thereof.

[0048] In Example 1, the height X of the light source panel 32 (height of the substrate 33) was 0.46 m, and the width Y of the light source panel 32 (width of the substrate 33) was 1.196 m. The interval Z between the light source panels 32 was 0.1 m in Example 1. Therefore, the volume F of the growth space was 0.055 m. 3 It was. In Example 2, the height X of the light source panel 32 was 0.46 m, and the width Y of the light source panel 32 was 0.596 m. The spacing Z between the light source panels 32 was 0.06 m in Example 2. Therefore, the volume F of the cultivation space was 0.0164 m. 3 It was.

[0049] In Example 1, the height X1 (see FIG. 3) of the region (light output region) on each substrate 33 where the LED chips 34 are mounted is 0.405 m, and the width Y1 of the region is 1.156 m. Therefore, the total area D of the regions on which the LED chips 34 are mounted in the two light source panels 32 is 0.936 m. 3 It was. In Example 1, 5940 LED chips 34 were mounted in the area of ​​each substrate 33 where the LED chips 34 were mounted. Specifically, 45 LED chips 34 were arranged at equal intervals in the height X direction, and 132 LED chips 34 were arranged at equal intervals in the width Y direction. The pitch of the LED chips 34 in the height X direction was about 9.2 mm, and the pitch of the LED chips 34 in the width Y direction was about 8.8 mm. The number C of the LED chips 34 used in the two light source panels 32 was 11,880.

[0050] In Example 2, the height X1 (see FIG. 3) of the area on each substrate 33 where the LED chips 34 are mounted is 0.405 m, and the width Y1 of the area is 0.556 m. Therefore, the total area D of the areas on which the LED chips 34 are mounted in the two light source panels 32 is 0.450 m. 3 It was. In Example 2, 2970 LED chips 34 were mounted in the area of ​​each substrate 33 where the LED chips 34 were mounted. Specifically, 45 LED chips 34 were arranged at equal intervals in the height X direction, and 66 LED chips 34 were arranged at equal intervals in the width Y direction. The pitch of the LED chips 34 in the height X direction was about 9.2 mm, and the pitch of the LED chips 34 in the width Y direction was about 8.5 mm. The number C of LED chips 34 used in the two light source panels 32 was 5940.

[0051] In both Examples 1 and 2, each LED chip 34 was a "Sanan 2835" type with a color temperature of 5,000K manufactured by San'an Optoelectronics Co. Ltd. (Hubei Province, China). The thickness t (see FIG. 4) of each LED chip 34 was 0.8 mm. Each LED chip 34 had a vertical length (length in the height direction X) of 2.8 mm and a horizontal length (length in the width direction Y) of 3.5 mm, and the light-emitting area (light output area) A of the artificial light Li per LED chip 34 was 9.8×10 -6 m 2 It was.

[0052] In each example, the LED chip 34 was supplied with the same current and voltage to emit artificial light Li with the same photon flux density. However, a higher current was passed through the LED chip 34 in Example 1 than in Example 2. As a result, the photon flux density B of the artificial light Li emitted from each LED chip 34 was 1,206 μmol m in Example 1. -2 ·s -1 In Example 2, it is 600 μmol m -2 ·s -1 In either case, the photon flux density B was less than the photosynthetic saturation intensity L of soybean leaves. Therefore, when the plant 200 is a soybean, it is possible to avoid saturation of the photosynthetic efficiency of the plant 200 and reduce waste of light energy.

[0053] In Example 1, the photon flux G per unit volume in the growth space 30 is A×B×C / F=2,553 μmol m -3 ·s -1 and the photosynthetic compensation photon flux M (200 μmol m) per unit volume in the growth space 30 at the flowering and mid-grain filling stages of soybean. -3 ·s -1 In Example 2, G = A × B × C / F = 2,123 μmol m -3 ·s -1 and the photosynthetic compensation photon flux M (200 μmol m -3 ·s -1) was sufficiently larger than that in Example 1. Therefore, in both Examples 1 and 2, the growth space 30 can promote the growth of soybean leaves at the flowering stage and the middle stage of grain filling.

[0054] In both Examples 1 and 2, a large number of ventilation holes 35 with a diameter of 3.5 mm were formed so that the temperature in the growth space 30 was 50° C. or less. In Example 1, 44 ventilation holes 35 were arranged at equal intervals in the height X direction and 131 ventilation holes 35 were arranged at equal intervals in the width Y direction in the region where the LED chips 34 were mounted on each substrate 33. In Example 2, 44 ventilation holes 35 were arranged at equal intervals in the height X direction and 65 ventilation holes 35 were arranged at equal intervals in the width Y direction in the region where the LED chips 34 were mounted on each substrate 33. Each ventilation hole 35 was disposed at the center of four adjacent LED chips 34.

[0055] The inventors have conducted tests to confirm the effectiveness of embodiments of the present invention. Figure 7 shows parameters of two examples of plant growing devices used in the tests. In both Example 3 and the Comparative Example, as shown in Figures 1 and 2, two light source panels 32 were arranged in parallel so that the growth space 30 was interposed between the two light source panels 32. In each light source panel 32, the substrate 33 was made of aluminum, and a water-resistant film was formed on the surface thereof.

[0056] In both Example 3 and the Comparative Example, the height X of the light source panel 32 (height of the substrate 33) was 0.46 m, and the width Y of the light source panel 32 (width of the substrate 33) was 0.596 m. The spacing Z between the light source panels 32 was 0.1 m. Therefore, the volume F of the growth space was 0.0274 m 3 It was.

[0057] In both Example 3 and the Comparative Example, the height X1 (see FIG. 3) of the region (light output region) on each substrate 33 where the LED chips 34 are mounted is 0.34 m, and the width Y1 of the region is 0.48 m. Therefore, in both Example 3 and the Comparative Example, the total area D of the regions on the two light source panels 32 where the LED chips 34 are mounted is 0.326 m. 3 It was.

[0058] In both Example 3 and the Comparative Example, 896 LED chips 34 were mounted in the area where the LED chips 34 were mounted in each substrate 33. Therefore, in both Example 3 and the Comparative Example, the number C of LED chips 34 used in the two light source panels 32 was 1,792.

[0059] In both Example 3 and the Comparative Example, the LED chips 34 used were the same as those in Examples 1 and 2. Therefore, the light-emitting area A of the artificial light Li per LED chip 34 was 9.8×10 -6 (m 2 ·Pieces -1 ) was.

[0060] In each of Example 3 and the Comparative Example, the LED chip 34 was given the same current and voltage, and artificial light Li was emitted with the same photon flux density. Thus, Example 3 and the Comparative Example were in approximately the same environment. However, in the Comparative Example, a higher current was passed through the LED chip 34 than in Example 3. As a result, in Example 3, the photon flux density B of the artificial light Li emitted from each LED chip 34 was 1,900 μmol m -2 ·s -1 was less than the photosynthetic saturation intensity L of soybean leaves. Therefore, when the plant 200 is a soybean, it is possible to avoid saturation of the photosynthetic efficiency of the plant 200 and reduce waste of light energy. On the other hand, in the comparative example, the photon flux density B was 5,700 μmol m -2 ·s -1 which was much larger than the photosynthetic saturation intensity L of soybean leaves. Therefore, when the plant 200 is a soybean, the photosynthetic efficiency of the plant 200 is saturated, and a large amount of light energy is wasted.

[0061] In Example 3, the photon flux G per unit volume in the growth space 30 is A×B×C / F=1217 μmol m -3 ·s -1 and the photosynthetic compensation photon flux M (200 μmol m) per unit volume in the growth space 30 at the flowering and mid-grain filling stages of soybean.-3 ·s -1 ) was greater. Therefore, in Example 3, the growth of soybean leaves at the flowering stage and the middle of the grain filling stage can be promoted. On the other hand, in the comparative example, G = A × B × C / F = 3651 μmol m -3 ·s -1 , which was three times that of G in Example 3. Therefore, in the comparative example as well, the growth of soybean leaves at the flowering stage and the middle stage of grain filling can be promoted in the growing space 30.

[0062] In both Example 3 and the Comparative Example, numerous ventilation holes 35 with a diameter of 3.5 mm were formed so that the temperature in the growth space 30 would be 50° C. or less.

[0063] In both Example 3 and the Comparative Example, soybeans were grown. The soybean variety was Hatsudarum. In both Example 3 and the Comparative Example, a 12-hour period in which the LED chip 34 was illuminated and a 12-hour period in which the LED chip 34 was not illuminated were repeated. The number of soybean seeds harvested (number of harvested beans) is shown in FIG. 7.

[0064] In Example 3, the number of beans harvested was 217, which was less than the 394 in the Comparative Example. This is because in the Comparative Example, the photon flux density B and the photon flux G per unit volume in the cultivation space 30 were three times those in Example 3. However, the number of beans harvested in the Comparative Example was not three times that of Example 3. The number of beans per energy (N / B) in Example 3 was 0.11, whereas it was 0.07 in the Comparative Example. Therefore, in Example 3, soybeans could be grown with higher energy efficiency than in the Comparative Example.

[0065] Although the present invention has been shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that changes may be made in form and detail without departing from the scope of the invention as set forth in the appended claims. Such changes, modifications and alterations are intended to be embraced within the scope of the invention.

[0066] In the above embodiment, the plant 200 to be grown is a soybean, but the plant 200 is not limited to a soybean and may be any plant that can be grown with artificial light.

[0067] In the above embodiment, the substrate 33 of the light source panel 32 is a flat plate, but as shown in Fig. 8, the substrate 33 may be a corrugated plate. Fig. 8 is a vertical cross-sectional view of the light source panel 32 seen in the same manner as in Fig. 3. A corrugated plate can dissipate more heat generated by the LED chips 34 than a flat plate.

[0068] In the above embodiment, the light source panel 32 has an LED chip 34 as a light output unit. However, the light source panel 32 may have other light output units. For example, as shown in Fig. 9, the light source panel 32 of the modified embodiment has output terminals 36a of multiple optical fibers 36. The output terminals 36a are fitted into holes formed in the light source panel 32, and output artificial light toward the left side of the figure. The input terminals of these optical fibers 36 are connected to a light source device 37 that supplies artificial light to the optical fibers 36. The light source device 37 may be a laser or a sunlight collecting mechanism. Even when the light source device 37 is a sunlight collecting mechanism, the optical fibers 36 have a propagation loss according to the wavelength, so that the light output from the output terminal 36a of the optical fibers 36 is artificial light, not natural light itself.

[0069] Aspects of the invention are also described in the following numbered clauses. Article 1. A plant growing device for growing plants using artificial light, A growing space for growing the plant; At least one light source panel that irradiates the cultivation space with artificial light; The light source panel includes a substrate and a plurality of light output units arranged on the substrate at intervals from one another; The photon flux density B (μmol m -2 ·s -1 ) is equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant. A plant growing device characterized by the above.

[0070] Clause 2. Photon flux G (μmol m -3 ·s -1 ) is the light compensation point H(μmol·m -2 ·s -1 ) and the cumulative leaf area K(m 2 m -3 ) is the photosynthetic compensation photon flux M (μmol m -3 ·s -1 ) 2. A plant growing device according to claim 1, characterized in that In this case, the growth of plant leaves in the growing space can be promoted.

[0071] Clause 3. The optical output area of ​​the artificial light per one optical output unit is A (m 2 ·Pieces -1 ), The number of the light output units of the light source panel is C (units), The volume of the growth space is F(m 3 ), The light compensation point H (μmol m -2 ·s -1 ) and the cumulative leaf area K(m 2 m -3 ) is the photosynthetic compensation photon flux M (μmol m -3 ·s -1 ) satisfies the following formula: 3. A plant growing device according to claim 2, characterized in that M <A×B×C / F In this case, the growth of plant leaves in the growing space can be promoted.

[0072] Clause 4. The photosynthetic saturation light intensity L of the leaves of the plant is 2000 μmol m -2 ·s -1 and The photosynthetic compensation photon flux M of the plant per unit volume in the growth space is 200 μmol m -3 ·s -1is 4. A plant growing device according to claim 2 or 3, characterized in that In this case, if the plant is soybean, the photon flux density B of the artificial light emitted from each light output unit is 2000 μmol m -2 ·s -1 By keeping the photon flux G per unit volume in the growing space at 200 μmol m or less, it is possible to avoid saturation of photosynthetic efficiency and reduce the waste of light energy. -3 ·s -1 or A × B × C / F > 200 μmol m -3 ·s -1 This can promote the growth of soybean leaves in the growing space.

[0073] Clause 5. The at least one light source panel irradiates the plant with artificial light from the side. 5. A plant growing device according to any one of claims 1 to 4, characterized in that In this case, the photon flux G per unit volume can be made as uniform as possible between the upper and lower parts of the growing space, regardless of the growth stage of the plant, particularly the state of leaf growth.

[0074] Clause 6. The light source panel includes two light source panels. The two light source panels face each other, the growing space is interposed between the two light source panels, and the two light source panels irradiate the plant with artificial light from both sides. 6. A plant growing device according to claim 5, characterized in that In this case, the photon flux G per unit volume can be made as uniform as possible on both sides of the plant.

[0075] Clause 7. The distance between the two light source panels is smaller than the width of the light output area in which the light output portion of the light source panel corresponding to one of the plants is arranged. 7. A plant growing device according to claim 6, characterized in that In this case, since the interval between the light source panels is small, it is possible to minimize the spread and attenuation of the artificial light from the light output unit and reduce energy loss. In addition, by reducing the interval between the light source panels in the plant cultivation device, it is possible to prevent the plant cultivation device from becoming large.

[0076] Clause 8. The substrate of the light source panel is formed with a plurality of ventilation holes. 8. A plant growing device according to any one of clauses 1 to 7, characterized in that In this case, the plants are prevented from being overheated by heat dissipation from the light source panel.

[0077] Clause 9. The substrate of the light source panel is formed of a material that reflects light. 9. A plant growing device according to any one of clauses 1 to 8, characterized in that In this case, the efficiency of utilizing artificial light within the cultivation space can be improved.

[0078] Clause 10. The light output unit is an LED chip. 10. A plant growing device according to any one of clauses 1 to 9, characterized in that

[0079] Clause 11. The optical output section is an output terminal of an optical fiber, and the input terminal of the optical fiber is connected to a light source device. 10. A plant growing device according to any one of clauses 1 to 9, characterized in that

[0080] Article 12. A method for growing plants using artificial light, comprising: irradiating a cultivation space in which the plant is grown with artificial light from at least one light source panel having a plurality of light output units arranged at intervals on a substrate; The photon flux density B (μmol m -2 ·s -1 ) is equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant. A method for growing plants comprising the steps of:

[0081] Clause 13. Photon flux G (μmol m -3 ·s -1 ) is the light compensation point H(μmol·m -2 ·s -1 ) and the cumulative leaf area K (m 2 m -3 ) is the photosynthetic compensation photon flux M (μmol m -3 ·s -1 ) Item 12. The plant cultivation method according to item 11, In this case, the growth of plant leaves in the growing space can be promoted.

[0082] Clause 14. The optical output area of ​​the artificial light per one optical output unit is A (m 2 ·Pieces -1 ), The number of the light output units of the light source panel is C (units), The volume of the growth space is F(m 3 ), The light compensation point H (μmol m -2 ·s -1 ) and the cumulative leaf area K (m 2 m -3 ) is the photosynthetic compensation photon flux M (μmol m -3 ·s -1 ) satisfies the following formula Item 14. The plant cultivation method according to item 13, M <A×B×C / F In this case, the growth of plant leaves in the growing space can be promoted. [Explanation of symbols]

[0083] 1... plant cultivation device, 200... plant, 30... cultivation space, 32, 32A... light source panel, 33... substrate, 34... LED chip (light output section), 35... ventilation hole, 36... optical fiber, 36a... output terminal, 37... light source device

Claims

1. A plant growing device for growing plants using artificial light, A growing space for growing the plant; At least one light source panel that irradiates the cultivation space with artificial light; The light source panel includes a substrate and a plurality of light output units arranged on the substrate at intervals from one another; The photon flux density B (μmol m -2 ・s -1 ) is equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant. A plant growing device characterized by the above.

2. The photon flux G (μmol m -3 ・s -1 ) is the light compensation point H (μmol・m -2 ・s -1 ) and the cumulative leaf area K (m 2 ・m -3 ) the photosynthetic compensation photon flux M (μmol m -3 ・s -1 ) 2. The plant growing device according to claim 1 .

3. The light output area of ​​the artificial light per light output unit is A (m 2 ・Individuals -1 ), The number of the light output units of the light source panel is C (units), The volume of the growth space is F (m 3 ) The light compensation point H (μmol・m -2 ・s -1 ) and the cumulative leaf area K (m 2 ・m -3 ) the photosynthetic compensation photon flux M (μmol m -3 ・s -1 ) satisfies the following formula:

3. The plant growing device according to claim 2 . M < A x B x C / F

4. The photosynthetic saturation light intensity L of the leaves of the plant is 2000 μmol m -2 ・s -1 and The photosynthetic compensation photon flux M of the plant per unit volume in the growth space is 200 μmol m -3 ・s -1 is 4. The plant growing device according to claim 2 or 3.

5. The at least one light source panel irradiates the plant with artificial light from a side.

3. The plant growing device according to claim 1 or 2.

6. The light source panel includes two of the light sources. The two light source panels face each other, the growing space is interposed between the two light source panels, and the two light source panels irradiate the plant with artificial light from both sides.

6. The plant growing device according to claim 5.

7. The distance between the two light source panels is smaller than the width of a light output area in which the light output unit of the light source panel corresponding to one of the plants is arranged.

7. The plant growing device according to claim 6.

8. The substrate of the light source panel is formed with a plurality of ventilation holes.

3. The plant growing device according to claim 1 or 2.

9. The light output unit is an LED chip.

3. The plant growing device according to claim 1 or 2.

10. A method for growing plants using artificial light, comprising: irradiating a cultivation space in which the plant is grown with artificial light from at least one light source panel having a plurality of light output units arranged at intervals on a substrate; The photon flux density B (μmol m -2 ・s -1 ) is equal to or less than the photosynthetic saturation light intensity L of the leaves of the plant. A method for growing plants comprising the steps of:

11. The photon flux G (μmol m -3 ・s -1 ) is the light compensation point H (μmol・m -2 ・s -1 ) and the cumulative leaf area K (m 2 ・m -3 ) the photosynthetic compensation photon flux M (μmol m -3 ・s -1 ) The method for growing a plant according to claim 10 .

12. The light output area of ​​the artificial light per light output unit is A (m 2 ・Individuals -1 ), The number of the light output units of the light source panel is C (units), The volume of the growth space is F (m 3 ) The light compensation point H (μmol・m -2 ・s -1 ) and the cumulative leaf area K (m 2 ・m -3 ) the photosynthetic compensation photon flux M (μmol m -3 ・s -1 ) satisfies the following formula: The method for growing a plant according to claim 11 . M < A x B x C / F

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