Plant growth device and plant growth method

Abstract

To reduce cost without reducing yield.SOLUTION: A plant growth device, which uses artificial light to grow plants, comprises: a growing space for growing a plant; at least one light source panel for irradiating the growing space with artificial light; a cultivation tank in which a liquid fertilizer, which is a nutrient solution containing a fertilizer to be fed to the plant, is stored and at least the roots of the plant are disposed; a measurement device for repeatedly measuring the amounts corresponding to the fertilizer absorption amount of the plant; and an environment control device which, when the rate of decrease in the amount measured by the measurement device within a set period is larger than a threshold value, controls the growth environment for the plant to be changed to an environment where photosynthesis of the plant is suppressed.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 from LED (light emitting diode) light sources, etc., 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] Generally, outdoor plants grow in response to changes in the natural environment throughout the year. For example, beans flower and produce pods in response to changes in day length. When the pods form, the amount of photosynthesis also decreases. Water, light, CO2, and fertilizer are important factors in the photosynthesis of agricultural crops.

[0006] The applicant believes that in conventional artificial light cultivation, in order to maximize crop yield, water, light, CO2, and fertilizer, which are important factors for photosynthesis, are often provided in excess.

[0007] Therefore, the present invention provides a plant growing device and a plant growing method that can reduce costs without reducing yields. [Means for solving the problem]

[0008] In one embodiment of the present invention, there is provided a plant growing device for growing a plant with artificial light, the plant growing device comprising: a growing space for growing the plant; at least one light source panel for irradiating the growing space with artificial light; a cultivation tank for containing liquid fertilizer, which is a nutrient solution containing fertilizer to be given to the plant, and in which at least the roots of the plant are placed; a measuring device for repeatedly measuring an amount corresponding to an amount of fertilizer absorbed by the plant; and an environmental control device for controlling the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the amount measured by the measuring device within a set period is greater than a threshold value.

[0009] In another aspect of the present invention, there is provided a plant-growing device for growing a plant with artificial light, the plant-growing device comprising: a growing space for growing the plant; at least one light source panel for irradiating the growing space with artificial light; a cultivation tank in which at least the roots of the plant are placed; a measuring device for non-destructively and repeatedly measuring an electrical characteristic corresponding to a sugar concentration of a liquid in the tissue of the plant; and an environmental control device for controlling the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the sugar concentration within a set period is greater than a threshold value.

[0010] In another aspect of the present invention, there is provided a plant growing device for growing a plant with artificial light, the plant growing device comprising: a growing space for growing the plant, at least one light source panel for irradiating the growing space with artificial light, a cultivation tank in which at least the roots of the plant are placed, a measuring device for repeatedly measuring an electrical characteristic corresponding to the amount of fertilizer remaining in a sample taken from the plant or an individual plant of the same variety as the plant grown in the same environment for the same period as the plant, and an environmental control device for controlling the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the amount of fertilizer within a set period is greater than a threshold value.

[0011] In one aspect of the present invention, there is provided a method for cultivating a plant using artificial light, the method comprising: irradiating a cultivation space in which the plant is cultivated with artificial light; supplying a nutrient solution containing fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; repeatedly measuring an amount corresponding to an amount of fertilizer absorbed by the plant; and controlling the cultivation environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the measured amount within a set period is greater than a threshold value.

[0012] In another aspect of the present invention, there is provided a method for cultivating a plant using artificial light, the method comprising: irradiating a cultivation space in which the plant is cultivated with artificial light, supplying a fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed, non-destructively and repeatedly measuring an electrical characteristic corresponding to a sugar concentration of a liquid in the tissue of the plant, and controlling the cultivation environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the sugar concentration within a set period is greater than a threshold value.

[0013] In another aspect of the present invention, there is provided a method for cultivating a plant using artificial light, the method comprising: irradiating a cultivation space in which the plant is cultivated with artificial light; supplying a fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; repeatedly measuring an electrical characteristic corresponding to an amount of fertilizer remaining in a sample taken from the plant or an individual plant of the same variety as the plant cultivated in the same environment for the same period as the plant; and controlling the cultivation environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the amount of fertilizer within a set period is greater than a threshold value. Effect of the Invention

[0014] According to an embodiment of the present invention, the growing environment of a plant can be controlled to change to an environment that suppresses photosynthesis of the plant during the seed filling stage and / or maturity stage of the plant. Even if photosynthesis is suppressed during the seed filling stage and / or maturity stage, the yield of the seeds or rhizomes of the plant is not reduced, and costs can be reduced. Therefore, in artificial light cultivation, costs can be reduced without reducing the yield. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing an example of the schematic configuration of a plant growing device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of a cultivation unit of the plant growing device of FIG. 1. [Diagram 3] FIG. 2 is a front view of the light source panel of the cultivation unit. [Figure 4] FIG. 4 is a vertical cross-sectional view of the light source panel of FIG. [Diagram 5] 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 6] 1 is a graph showing the change in cumulative fertilizer absorption amount of soybeans. [Figure 7] 1 is a graph showing the change in cumulative fertilizer absorption amount of soybeans. [Figure 8] FIG. 5 is a schematic diagram showing an example of the schematic configuration of a plant growing device according to a second embodiment of the present invention. [Figure 9] FIG. 13 is a schematic diagram showing an example of the schematic configuration of a plant growing device according to a third embodiment of the present invention. [Figure 10] FIG. 13 is a schematic diagram showing an example of the schematic configuration of a plant growing device according to a fourth embodiment of the present invention. [Figure 11] FIG. 13 is a schematic diagram showing an example of the schematic configuration of a plant growing device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Various embodiments of the present invention will now be described with reference to the accompanying drawings, in which the drawings are not necessarily drawn to scale and some features may be exaggerated or omitted.

[0017] The plant growing device according to the embodiment is disposed in a plant factory. As shown in Fig. 1, a plant growing device 1 according to the first embodiment is provided with a number of cultivation units 2 for growing plants. The plants to be grown are, for example, agricultural crops such as beans, but may also be other plants that perform photosynthesis. The plant factory in which the plant growing device 1 according to the embodiment is arranged is provided with an air conditioning system 20. The air conditioning system 20 adjusts the environment of the area in which the plants are grown to temperature, humidity, and carbon dioxide (CO2) concentration suitable for growing plants.

[0018] 1 and 2, the cultivation unit 2 of the plant cultivation device 1 according to the first embodiment has an upper portion 10, a cultivation tank 12 arranged below the upper portion 10, and a support panel 14 attached to the upper end of the cultivation 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).

[0019] At least the roots (including the main root and lateral roots) of the plant 200 are placed in the cultivation tank 12, where the roots grow. The lower part of the stem of the plant 200 is also placed in the cultivation tank 12. The support panel 14 supports the plant 200.

[0020] The cultivation tank 12 is a container that contains a nutrient solution (liquid fertilizer, i.e., liquid fertilizer) 16 that contains fertilizer to be given to the roots of the plants 200. A nutrient solution supply system 18 is connected to the cultivation tank 12, and the nutrient solution supply system 18 supplies the nutrient solution 16 to the cultivation tank 12.

[0021] The upper part 10 of the cultivation unit 2 has at least one light source panel 32 that irradiates the artificial light Li to the cultivation space 30. The light source panel 32 irradiates the artificial light Li to the plant 200 from the side. In this embodiment, the upper part 10 includes two light source panels 32 that are vertically oriented 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 artificial light Li to the plant 200 from both sides.

[0022] 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 emitting area of ​​the light source panel 32 corresponding to one plant 200. The light emitting area is an area in which an LED chip, which will be described later, is mounted.

[0023] The light source of the light source panel 32 may be, for example, a plurality of fluorescent lamps, a plurality of cold cathode fluorescent lamps, or a plurality of OLED (organic light-emitting diode) elements. However, in the embodiment, a plurality of LED (light-emitting diode) chips that generate less heat are used. 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 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. The LED chip 34 is mounted in a light emitting area of ​​the light source panel 32, the area having a height X1 and a width Y1.

[0024] The substrate 33 is provided with wiring (not shown) for lighting these LED chips 34. Outside the light source panel 32, a light emission control device 44 (see FIG. 1) is provided for simultaneously controlling the light emission of these LED chips 34.

[0025] A plurality of ventilation holes 35 are formed in the light-emitting region of 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, preventing the plants 200 from being overheated by heat dissipation from the light source panel 32 (it is to be noted that the air managed by the air-conditioning system 20 may be directly supplied to the growing space 30). 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 from each other 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.

[0026] 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.

[0027] 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.

[0028] The position of the light source panel 32 relative to the plant 200 and thus the cultivation space 30 is not limited, and 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.

[0029] However, in order to make the illuminance as uniform as possible in the cultivation space 30, the way the leaves grow should be taken into consideration. When artificial light Li is emitted from above the cultivation space 30, the artificial light Li is blocked by the upper leaves at a growth stage when the plant 200 has many leaves, resulting in low illuminance in the lower part of the cultivation space 30 and poor photosynthetic efficiency. Also, when the plants 200 grow densely, the growth of each individual plant varies.

[0030] Therefore, in this embodiment, the light source panel 32 is arranged 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 illuminance can be made as uniform as possible at the upper and lower parts of the cultivation space 30. Even if the plants 200 are densely grown, the artificial light Li can be supplied evenly to each individual plant, so that the variation in growth among the individual plants can be suppressed.

[0031] The number of light source panels 32 may be one. However, in order to make the illuminance as uniform as possible on both sides of the plant 200, in this embodiment, as shown in Fig. 1 and Fig. 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 illuminance can be made as uniform as possible on both sides of the plant 200, thereby improving the photosynthetic efficiency.

[0032] 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, and light energy may be wasted. In addition, the growth of each plant varies depending on the individual plant. Therefore, it is preferable to provide only two light source panels 32 as in this embodiment.

[0033] In the embodiment, the substrate 33 of the light source panel 32 is a flat plate, but as shown in Fig. 5, the substrate 33 may be a corrugated plate. Fig. 5 is a vertical cross-sectional view of the light source panel 32 seen in the same manner as in Fig. 4. A corrugated plate can dissipate more heat generated by the LED chips 34 than a flat plate.

[0034] To cool the plants 200 in the cultivation unit 2, the nutrient solution supply system 18 or the cultivation tank 12 may be cooled by a cooling device.

[0035] As shown in FIG. 1, the plant growing device 1 further includes a fertilizer absorption amount measuring device 40 and an environmental control device 42. The fertilizer absorption amount measuring device 40 repeatedly measures the amount of fertilizer absorption of the plant 200 in the cultivation unit 2 at unit time intervals (for example, every day). In this embodiment, the fertilizer absorption amount measuring device 40 has a sensor 40a, a liquid volume sensor 40b, and a fertilizer absorption amount calculation unit 40c.

[0036] The sensor 40a repeatedly (e.g., every day) measures the fertilizer concentration of the nutrient solution 16 in the cultivation tank 12. As the fertilizer concentration, the sensor 40a may measure the phosphate concentration that forms adenosine triphosphate, which is an energy component of the plant 200, or may measure the nitrogen concentration that forms protein in the plant 200. Alternatively, the sensor 40a may be a combination of a sensor that measures the phosphate concentration and a sensor that measures the nitrogen concentration. Alternatively, the sensor 40a may measure the electrical conductivity of the nutrient solution 16 in the cultivation tank 12. The fertilizer absorption amount calculation unit 40c described later can calculate the fertilizer concentration of the nutrient solution 16 in the cultivation tank 12 from the electrical conductivity using, for example, a conversion formula.

[0037] The liquid volume sensor 40b repeatedly measures the amount of nutrient solution 16 supplied from the nutrient solution supply system 18 to the cultivation tank 12 at unit time intervals (e.g., every day). The liquid volume sensor 40b may be, for example, a flow meter. Alternatively, the liquid volume sensor 40b may be a level gauge that measures the liquid level of the nutrient solution 16 in the cultivation tank 12, in which case the liquid volume sensor 40b may report the amount of nutrient solution 16 that has decreased to the nutrient solution supply system 18, and the nutrient solution supply system 18 may maintain the liquid level of the nutrient solution 16 constant.

[0038] The fertilizer absorption amount calculation unit 40c is a computer processor. The fertilizer absorption amount calculation unit 40c repeatedly calculates the cumulative fertilizer absorption amount (amount of fertilizer components absorbed by the plant 200) of the plant from sowing to the present time every unit period (e.g., every day) from the measurement results of the sensor 40a and the measurement results of the liquid volume sensor 40b. Alternatively, the fertilizer absorption amount calculation unit 40c may calculate the fertilizer absorption amount of the plant 200 per unit period (e.g., one day) every unit period (e.g., every day) from the measurement results of the sensor 40a and the measurement results of the liquid volume sensor 40b. The fertilizer absorption amount calculation unit 40c may calculate the amount of phosphoric acid absorbed by the plant 200, may calculate the amount of nitrogen absorbed by the plant 200, or may calculate both.

[0039] When the fertilizer concentration is constant, the cumulative fertilizer absorption amount is calculated by multiplying the fertilizer concentration of the nutrient solution 16 obtained from the measurement results of the sensor 40a by the cumulative liquid amount absorbed by the plant 200 obtained from the measurement results of the liquid volume sensor 40b. When the fertilizer concentration is constant, the fertilizer absorption amount per unit period is calculated by multiplying the fertilizer concentration of the nutrient solution 16 obtained from the measurement results of the sensor 40a by the liquid amount absorbed by the plant 200 per unit period obtained from the measurement results of the liquid volume sensor 40b.

[0040] When the fertilizer concentration changes, the cumulative fertilizer absorption amount A is calculated by the following formula. A = (C2*L2) - (C1*L1) Here, C1 is the fertilizer concentration of the initial nutrient solution 16, and L1 is the volume of the initial nutrient solution 16. C2 is the fertilizer concentration of the final nutrient solution 16, and L2 is the volume of the final nutrient solution 16. When the fertilizer concentration changes, the amount of fertilizer absorbed per unit period is also calculated according to the above formula.

[0041] If the concentration of fertilizer in the cultivation tank 12 is always known, the sensor 40a is not necessary, and the fertilizer absorption amount calculation unit 40c can calculate the cumulative fertilizer absorption amount or the fertilizer absorption amount per unit period from the measurement results of the liquid volume sensor 40b.

[0042] The amount of fertilizer absorption measured by the fertilizer absorption amount measuring device 40 is notified to the environmental control device 42. The environmental control device 42 is a computer processor. The environmental control device 42 controls at least one of the air conditioning system 20, the light emission control device 44, and the nutrient solution supply system 18 based on the change in the measured amount of fertilizer absorption.

[0043] The policy of environmental control based on the change in the amount of fertilizer absorption will be described with reference to the graphs in Figures 6 and 7. The curves in Figure 6 show the change in cumulative fertilizer absorption when soybeans (variety: Hatsudarum) are grown in a plant factory. The vertical axis is the converted value of the cumulative fertilizer absorption per four plants or per plant. Curve a shows the change in the amount of fertilizer absorption when five soybean plants in the cultivation space 30 are grown in a cultivation unit 2 in which artificial light Li is irradiated from the side by one light source panel 32. Curve b shows the change in the amount of fertilizer absorption when two soybean plants in the cultivation space 30 are grown in a cultivation unit 2 in which artificial light Li is applied from above by one light source panel 32. In the case of curve b, the amount of fertilizer absorption is less than that in the case of curve a. This is because, as described above, when artificial light Li is applied from above, the artificial light Li is blocked by the upper leaves, resulting in poor photosynthetic efficiency of the lower leaves.

[0044] The growth stages of photosynthetic plants up to maturity can be classified into early vegetative growth, mid vegetative growth, flowering and pod number determination, seed enlargement, and maturity. During the early vegetative growth stage, plants actively photosynthesize and absorb fertilizer, and their branches and leaves flourish. In soybeans, the mid-vegetative growth stage is the period of flower bud differentiation, and during the flowering and pod number determination stage, flower buds are produced and pods are formed. In outdoor environments, the flowering and pod number determination stages of soybeans vary depending on the conditions, but are generally about 70 days after sowing. In addition, the mid-vegetative growth stage and the flowering and pod number determination stages are also periods during which vegetative growth and reproductive growth proceed simultaneously. During the seed filling stage, photosynthetic products (sugars) produced by photosynthesis are translocated to the seeds or rhizomes, causing the seeds or rhizomes to swell. The seed filling stage of soybeans varies depending on the conditions, but is generally between 70 and 110 days after sowing. During the maturity stage, the seeds or rhizomes are fully ripe. In the case of soybeans, the seeds dry out during the maturity stage. Outdoors, soybeans mature generally between 110 and 150 days after planting, depending on conditions.

[0045] In a cultivation environment in a plant factory, plants usually develop faster than in an outdoor environment. In Figure 6, in the case of curve a, the increase in the cumulative amount of fertilizer absorption slowed down 44 days after sowing, and the increase in the cumulative amount of fertilizer absorption slowed down even more on the 50th day after sowing. In other words, the amount of fertilizer absorption per day decreased on the 44th day after sowing, and the amount of fertilizer absorption per day decreased on the 50th day after sowing. In the case of curve a, soybeans entered the maturity stage 50 days after sowing. In the case of curve b, which shows a small amount of fertilizer absorption equivalent to when artificial light Li is irradiated from above on soybeans, a similar change in the amount of fertilizer absorption was observed earlier than curve a because photosynthesis was suppressed.

[0046] The curves in Figure 7 show the change in cumulative fertilizer absorption when soybeans (variety: Sachiyutaka) are grown in a plant factory. The vertical axis is the converted value of the cumulative fertilizer absorption per four plants or per plant. Curve c shows the change in the amount of fertilizer absorption when soybeans are grown at a constant temperature. Curve d shows the change in the amount of fertilizer absorption when soybeans are grown by switching the temperature every 12 hours to simulate day and night. In both cases, artificial light Li was applied to the soybeans from above.

[0047] For curve c, the increase in cumulative fertilizer absorption slowed down 50 days after sowing, and the increase slowed even further on the 70th day after sowing. For curve c, the maturity stage began 70 days after sowing. For curve d, the increase in cumulative fertilizer absorption slowed down 48 days after sowing, and the increase slowed even further on the 73rd day after sowing. For curve d, the maturity stage began 73 days after sowing.

[0048] Therefore, although the time when soybeans enter the seed filling stage differs depending on the growing environment, the amount of fertilizer absorption (in other words, the amount of fertilizer required) is significantly less during the seed filling stage than during the early vegetative growth stage, the middle vegetative growth stage, or the flowering and pod number determination stage. By monitoring the change in the amount of fertilizer absorption (a slowdown in the increase in the cumulative amount of fertilizer absorption, i.e., a decrease in the amount of fertilizer absorption per unit period), it is possible to recognize that soybeans have entered the seed filling stage. The same is thought to apply to other plants that perform photosynthesis. During the seed filling stage, the photosynthetic rate of the plant slows down, and the required amounts of light, CO2, and fertilizer, which are factors in photosynthesis, decrease. Therefore, when the change in the amount of fertilizer absorption corresponds to the seed filling stage of the plant, the above-mentioned environmental control device 42 (see FIG. 1) controls at least one of the air conditioning system 20, the light emission control device 44, and the nutrient solution supply system 18 to change the growing environment of the plant 200 to an environment that suppresses the photosynthesis of the plant 200. Even if photosynthesis is suppressed during the seed filling stage, the yield of the plant's seeds or rhizomes is not reduced, and costs can be reduced.

[0049] The trigger for the environmental control device 42 to change the cultivation environment to one that suppresses photosynthesis in this way (the trigger for determining that the plant has entered the seed enlargement stage) is when the rate of decrease in the increment of the cumulative amount of fertilizer absorption per unit period (e.g., one day) during the set period is greater than the threshold value (i.e., when the rate of decrease in the amount of fertilizer absorption per unit period during the set period is greater than the threshold value). Here, the "decrease rate" is the absolute value of the decrease rate, and the "threshold" is a positive value. The "threshold" corresponds to the seed enlargement stage of the plant, differs depending on the type and variety of the plant and the cultivation environment, and is determined based on the experience of cultivating plants. The "set period" does not mean a start time that is predetermined, but rather a length of time. Taking into account measurement errors, the "set period" is set to be longer than the unit period (e.g., one day). It is also known that the amount of fertilizer absorbed by plants changes depending on the phases of the moon, i.e., the gravitational force of the moon on the earth. Therefore, it is preferable that the environmental control device 42 corrects at least one of the threshold value and the set period according to the phase of the moon.

[0050] When the rate of decrease in the amount of fertilizer absorption per unit period within the set period is greater than the threshold value, the environmental control device 42 may control the light emission control device 44 to at least one of decreasing the amount of light emission of the artificial light Li, shortening the irradiation time of the artificial light Li, and reducing the blue wavelength region of the artificial light Li. In other words, changing the growth environment of the plant 200 to an environment that suppresses the photosynthesis of the plant 200 may be at least one of decreasing the amount of light emission of the artificial light Li, shortening the irradiation time of the artificial light Li, and reducing the blue wavelength region of the artificial light Li. The decrease in the amount of light emission of the artificial light Li may be performed by decreasing the power supplied to each light source (e.g., the LED chip 34) or by reducing the number of light sources that are turned on. In this case, the environmental control device 42 provides a command signal to the light emission control device 44, and the light emission control device 44 controls the light source panel 32 according to the command signal. The reduction in the amount of light emitted can reduce costs. In addition, the reduction in the irradiation time can reduce costs.

[0051] Furthermore, costs can be reduced by reducing the blue wavelength range of artificial light Li. The wavelength range of light that contributes to photosynthesis is 400 to 700 nm. The shorter the wavelength of light, the greater the amount of energy per photon. In other words, for the same number of photons, short-wavelength light has a higher amount of energy, and long-wavelength light has a lower amount of energy. However, the amount of photosynthesis is correlated with the number of photons that hit the plant, not with the amount of light energy. Therefore, for the same number of photons, long-wavelength light has a higher energy efficiency for photosynthesis than short-wavelength light. And the power consumption required to generate short-wavelength light with a high amount of energy is greater than the power consumption required to generate long-wavelength light. Therefore, power consumption can be reduced by reducing the blue wavelength range of artificial light Li.

[0052] In addition, three types of photoreceptors are known in plants: phytochrome, cryptochrome, and phototropin. Phytochrome mainly performs photosynthesis in response to red light and far-red light, while cryptochrome and phototropin mainly perform photosynthesis in response to blue light. By reducing the blue wavelength range of artificial light Li, photosynthesis by cryptochrome and phototropin is suppressed, and the plant growth environment can be changed to one that suppresses plant photosynthesis. In order to reduce the blue wavelength region of the artificial light Li, the light emission control device 44 may replace the light source panel 32 used with another light source panel. Alternatively, when the light source panel 32 has LED chips 34 having different emission wavelength regions, the light emission control device 44 may stop the emission of the LED chips 34 that emit light in the blue wavelength region, and continue or newly start the emission of the LED chips 34 that emit light in the long wavelength region (e.g., red wavelength region). Alternatively, when the light source panel 32 has OLED elements having different emission wavelength regions, the light emission control device 44 may stop the emission of the OLED elements that emit light in the blue wavelength region, and continue or newly start the emission of the OLED elements that emit light in the long wavelength region. However, it is not necessarily necessary to completely stop the emission of all light sources that emit light in the blue wavelength region, and the power supplied to those light sources may be reduced, or the number of light sources that are turned on may be reduced.

[0053] When the rate of decrease in the amount of fertilizer absorption per unit period within a set period is greater than a threshold value, the environmental control device 42 may control the air conditioning system 20 to lower the temperature within the cultivation space 30, instead of or in addition to the above-mentioned control of the light emission control device 44. In other words, changing the cultivation environment of the plant 200 to an environment that suppresses the photosynthesis of the plant 200 may be achieved by lowering the temperature within the cultivation space 30. In this case, the environmental control device 42 provides a command signal to the air conditioning system 20, and the air conditioning system 20 lowers the temperature in accordance with the command signal. Lowering the temperature can reduce costs.

[0054] When the rate of decrease in the amount of fertilizer absorption per unit period within a set period is greater than a threshold value, the environmental control device 42 may control the air conditioning system 20 instead of or in addition to controlling the light emission control device 44 and / or the temperature to reduce the concentration of CO2 in the air within the cultivation space 30. In other words, changing the cultivation environment of the plant 200 to an environment that suppresses the photosynthesis of the plant 200 may reduce the concentration of CO2 in the air within the cultivation space 30. In this case, the environmental control device 42 provides a command signal to the air conditioning system 20, and the air conditioning system 20 reduces the concentration of CO2 in the air in accordance with the command signal. The reduction in the concentration of CO2 can reduce costs.

[0055] When the rate of decrease in the amount of fertilizer absorption per unit period within a set period is greater than a threshold value, the environmental control device 42 may reduce the amount of top dressing by controlling the nutrient solution supply system 18 instead of or in addition to controlling the light emission control device 44 and / or the air conditioning system 20. In other words, changing the growing environment of the plant 200 to an environment that suppresses the photosynthesis of the plant 200 may reduce the amount of top dressing. In this case, the environmental control device 42 gives a command signal to the nutrient solution supply system 18, and the nutrient solution supply system 18 reduces the amount of top dressing in accordance with the command signal. The nutrient solution supply system 18 reduces the concentration of fertilizer in the nutrient solution 16, for example. The reduction in the amount of top dressing can reduce costs.

[0056] In the first embodiment, when the rate of decrease in the amount of fertilizer absorption per unit period within a set period is greater than a threshold value, the environmental control device 42 changes the cultivation environment to an environment that suppresses photosynthesis. However, the fertilizer absorption amount measuring device 40 may repeatedly calculate the product of the amount of nutrient solution 16 supplied from the nutrient solution supply system 18 to the cultivation tank 12 within a unit period and the electrical conductivity of the nutrient solution 16 every unit period (e.g., every day), and when the rate of decrease in the product within a set period is greater than a threshold value, the environmental control device 42 may change the cultivation environment to an environment that suppresses photosynthesis.

[0057] Next, a plant growing device 1A according to a second embodiment of the present invention will be described with reference to Fig. 8. The plant growing device 1A has an in-plant fertilizer concentration measuring device 50 instead of the fertilizer absorption amount measuring device 40. The in-plant fertilizer concentration measuring device 50 measures the fertilizer concentration of the liquid inside the plant 200 that is actually being grown. In this embodiment, the plant fertilizer concentration measuring device 50 has a sensor 50a and a plant fertilizer concentration calculation unit 50b.

[0058] The sensor 50a is attached to a support bracket (not shown) and is disposed in close proximity to the plant 200 in the cultivation unit 2. The sensor 50a repeatedly measures an electrical characteristic corresponding to the fertilizer concentration of the liquid flowing through the plant 200 at unit time intervals (e.g., every day). For example, the sensor 50a may have a probe needle (not shown) that is inserted into the stem of a plant, and may use the probe needle inserted into the stem to measure the electrical properties (e.g., electrical conductivity or impedance) of the liquid flowing through the vascular bundle of the plant. The individual plant into which the probe needle is inserted may be changed from time to time. The electrical properties correspond to the fertilizer concentration of the liquid flowing through the vascular bundle of the plant. Inserting the probe needle into the stem of a plant is invasive (destructive) to the plant, adversely affecting the growth of the plant, and may even kill the plant in some cases. Therefore, the individual plant whose photosynthesis is suppressed by changing the growth environment by the environmental control device 42 may be different from the individual into which the probe needle is inserted. In other words, the sensor 50a may measure the electrical properties of the liquid flowing through a plant of the same variety that is different from the plant whose photosynthesis is suppressed but that has been grown in the same environment for the same period of time. Alternatively, the sensor 50a may have an organic electrochemical transistor, which may be used to non-destructively (non-invasively) measure the electrical properties (e.g., electrical conductivity, capacitance, or impedance) of the liquid flowing through the vascular bundle of the plant. In this case, the electrical properties correspond to the concentration of sugars (cellulose and sucrose) in the liquid in the vascular tissue of the plant, and also to the amount of fertilizer absorption. By using this method, which is non-destructive (non-invasive) to the plant, there is no adverse effect on the growth of the plant. Therefore, unless the individual plant to be measured dies for some reason, the individual plant whose photosynthesis is suppressed by changing the growth environment by the environmental control device 42 is the same as the individual plant to be measured.

[0059] The plant fertilizer concentration calculation unit 50b is a computer processor. The plant fertilizer concentration calculation unit 50b repeatedly calculates the fertilizer concentration of the liquid at unit time intervals (for example, every day) from the electrical characteristics of the liquid measured by the sensor 50a.

[0060] The fertilizer concentration calculated by plant fertilizer concentration calculation unit 50b is notified to environmental control device 42. When the rate of decrease in the fertilizer concentration within a set period is greater than a threshold based on the change in the measured fertilizer concentration, environmental control device 42 controls at least one of air conditioning system 20, light emission control device 44, and nutrient solution supply system 18. The "decrease rate" is the absolute value of the decrease rate, and the "threshold" is a positive value. The "threshold" corresponds to the seed enlargement stage of the plant, and varies depending on the type and variety of the plant and the growing environment, and is determined based on the experience of growing plants. The "set period" does not mean a start date that is predetermined, but rather a length of time. Taking into account measurement error, the "set period" is set to be longer than a unit period (e.g., one day). It is preferable that the environmental control device 42 corrects at least one of the threshold value and the set period according to the phase of the moon.

[0061] As in the first embodiment, the environmental control device 42 may control the light-emitting control device 44 to at least one of reducing the amount of light emitted by the artificial light Li, shortening the irradiation time of the artificial light Li, and reducing the blue wavelength region of the artificial light Li. Instead of or in addition to the above-mentioned control of the light-emitting control device 44, the environmental control device 42 may control the air-conditioning system 20 to reduce at least one of the temperature in the cultivation space 30 and the concentration of CO2 in the air. Instead of or in addition to the control of the light-emitting control device 44 and / or the air-conditioning system 20, the environmental control device 42 may control the nutrient solution supply system 18 to reduce the amount of top dressing. According to this embodiment, if the rate of decrease in the fertilizer concentration of the liquid actually flowing within the plant during a set period is greater than a threshold value, the growing environment of the plant can be changed to one that suppresses the photosynthesis of the plant.

[0062] Next, a plant growing device 1B according to a third embodiment of the present invention will be described with reference to Fig. 9. The plant growing device 1B has a remaining fertilizer amount measuring device 60 instead of the fertilizer absorption amount measuring device 40 and the plant fertilizer concentration measuring device 50. The remaining fertilizer amount measuring device 60 measures the amount of fertilizer remaining in a sample 61 collected from a plant 200 being grown in a cultivation unit 2. In this embodiment, the remaining fertilizer amount measuring device 60 has a sensor 60a and a remaining fertilizer amount calculating unit 60b.

[0063] The sensor 60a repeatedly measures an electrical characteristic (e.g., electrical conductivity or impedance) corresponding to the amount of fertilizer remaining in the sample 61 at unit time intervals (e.g., every day). The sample 61 includes at least one of the leaves and stems of the plant 200 grown in the cultivation unit 2. The amount of fertilizer remaining in the sample 61 corresponds to the amount of fertilizer absorbed. Collecting the sample 61 from the plant is invasive (destructive) to the plant, adversely affects the growth of the plant, and may even kill the plant in some cases. Therefore, the individual plant whose photosynthesis is suppressed by changing the growth environment by the environmental control device 42 may be different from the individual from which the sample 61 is collected. In other words, the sensor 60a may measure the electrical characteristic in the sample 61 collected from a plant of the same variety that is different from the plant whose photosynthesis is suppressed but that is grown in the same environment for the same period.

[0064] The remaining fertilizer amount calculation unit 60b is a computer processor. The remaining fertilizer amount calculation unit 60b repeatedly calculates the amount of fertilizer remaining in the sample 61 at unit intervals (for example, every day) from the electrical characteristics of the sample 61 measured by the sensor 60a.

[0065] The amount of fertilizer calculated by the remaining fertilizer amount calculation unit 60b is notified to the environmental control device 42. When the rate of decrease in the amount of fertilizer within a set period is greater than a threshold based on the change in the measured amount of fertilizer, the environmental control device 42 controls at least one of the air conditioning system 20, the light emission control device 44, and the nutrient solution supply system 18. The "decrease rate" is the absolute value of the decrease rate, and the "threshold" is a positive value. The "threshold" corresponds to the seed enlargement stage of the plant, and varies depending on the type and variety of the plant and the growing environment, and is determined based on the experience of growing plants. The "set period" does not mean a start date that is predetermined, but rather a length of time. Taking into account measurement error, the "set period" is set to be longer than a unit period (e.g., one day). It is preferable that the environmental control device 42 corrects at least one of the threshold value and the set period according to the phase of the moon.

[0066] As in the first embodiment, the environmental control device 42 may control the light-emitting control device 44 to at least one of reducing the amount of light emitted by the artificial light Li, shortening the irradiation time of the artificial light Li, and reducing the blue wavelength region of the artificial light Li. Instead of or in addition to the above-mentioned control of the light-emitting control device 44, the environmental control device 42 may control the air-conditioning system 20 to reduce at least one of the temperature in the cultivation space 30 and the concentration of CO2 in the air. Instead of or in addition to the control of the light-emitting control device 44 and / or the air-conditioning system 20, the environmental control device 42 may control the nutrient solution supply system 18 to reduce the amount of top dressing. According to this embodiment, if the rate of decrease in the amount of fertilizer in a sample collected from a plant within a set period of time is greater than a threshold, the growing environment of the plant can be changed to an environment that suppresses the plant's photosynthesis.

[0067] Next, a plant growing device 1C according to a fourth embodiment of the present invention will be described with reference to Fig. 10. The plant growing device 1C is similar to the plant growing device 1A of the second embodiment (Fig. 8), but has a cultivation unit 2A and a fertilizer supply system 78 instead of the cultivation unit 2 and the nutrient solution supply system 18. The cultivation unit 2A has the same upper portion 10 and support panel 14 as the cultivation unit 2, and has a cultivation tank 72 that contains culture soil 76 instead of the cultivation tank 12 that contains the nutrient solution 16. The fertilizer supply system 78 supplies fertilizer to the culture soil 76 in the cultivation tank 72. The fertilizer supplied by the fertilizer supply system 78 may be liquid fertilizer, powder fertilizer, or granular fertilizer. Furthermore, the plant cultivation device 1C has a water supply system 79. The water supply system 79 periodically supplies water to the culture soil 76 in the cultivation tank 72.

[0068] The plant growing device 1C has an in-plant sugar content measuring device 70. The in-plant sugar content measuring device 70 measures the sugar concentration of the liquid inside the plant 200 that is actually being grown. In this embodiment, the plant sugar content measuring device 70 has a sensor 70a and an plant sugar content calculation unit 70b.

[0069] The sensor 70a is attached to a support bracket (not shown) and is disposed close to the plant 200 in the cultivation unit 2. The sensor 70a non-destructively and repeatedly measures an electrical characteristic corresponding to the concentration of sugar (cellulose and sucrose) of the liquid in the vascular tissue of the plant 200. The sensor 70a may be the same as the example having an organic electrochemical transistor among the examples of the sensor 50a of the second embodiment. Specifically, the sensor 70a uses an organic electrochemical transistor to non-destructively (non-invasively) measure an electrical characteristic (e.g., electrical conductivity, capacitance, or impedance) of the liquid flowing in the vascular bundle of the plant. In this case, the electrical characteristic corresponds to the concentration of sugar (cellulose and sucrose) of the liquid in the vascular tissue of the plant and also corresponds to the amount of fertilizer absorption. By using this method that is non-destructive (non-invasive) to the plant, there is no adverse effect on the growth of the plant. Therefore, unless the individual plant being measured dies for some reason, the individual plant whose photosynthesis is suppressed by changing the growing environment by the environmental control device 42 is the same as the individual plant being measured.

[0070] The plant sugar content calculation unit 70b is a computer processor. The plant sugar content calculation unit 70b repeatedly calculates the sugar concentration of the liquid at unit time intervals (for example, every day) from the electrical characteristics of the liquid measured by the sensor 70a.

[0071] The sugar concentration calculated by the in-plant sugar content calculation unit 70b is notified to the environmental control device 42. When the rate of decrease in the sugar concentration within a set period is greater than a threshold based on the change in the measured sugar concentration, the environmental control device 42 controls at least one of the air conditioning system 20, the light emission control device 44, the fertilizer supply system 78, and the water supply system 79. The "decrease rate" is the absolute value of the decrease rate, and the "threshold" is a positive value. The "threshold" corresponds to the seed enlargement stage of the plant, and varies depending on the type and variety of the plant and the growing environment, and is determined based on the experience of growing plants. The "set period" does not mean a start date that is predetermined, but rather a length of time. Taking into account measurement error, the "set period" is set to be longer than a unit period (e.g., one day). It is preferable that the environmental control device 42 corrects at least one of the threshold value and the set period according to the phase of the moon.

[0072] As in the first embodiment, the environmental control device 42 may control the light-emitting control device 44 to at least one of reducing the amount of light emitted by the artificial light Li, shortening the irradiation time of the artificial light Li, and reducing the blue wavelength region of the artificial light Li. Instead of or in addition to the above-mentioned control of the light-emitting control device 44, the environmental control device 42 may control the air-conditioning system 20 to reduce at least one of the temperature in the cultivation space 30 and the concentration of CO2 in the air. Instead of or in addition to the control of the light-emitting control device 44 and / or the air-conditioning system 20, the environmental control device 42 may control the fertilizer supply system 78 to reduce the amount of top dressing. Instead of, or in addition to, controlling the light control device 44, the air conditioning system 20 and / or the fertilizer supply system 78, the environmental control device 42 may control the water supply system 79 to reduce the amount of water supplied to the soil 76. According to this embodiment, if the rate of decrease in the sugar concentration of the liquid actually flowing through the plant during a set period is greater than a threshold, the plant's growing environment can be changed to one that suppresses the plant's photosynthesis. The sensor 70a is non-destructive (non-invasive) to the plant and does not adversely affect the growth of the plant.

[0073] Next, a plant growing device 1D according to a fifth embodiment of the present invention will be described with reference to Fig. 11. The plant growing device 1D is similar to the plant growing device 1B of the third embodiment (Fig. 9), but has a cultivation unit 2A and a fertilizer supply system 78 instead of the cultivation unit 2 and the nutrient solution supply system 18. The cultivation unit 2A has the same upper portion 10 and support panel 14 as the cultivation unit 2, and has a cultivation tank 72 that contains culture soil 76 instead of the cultivation tank 12 that contains the nutrient solution 16. The fertilizer supply system 78 supplies fertilizer to the culture soil 76 in the cultivation tank 72. The fertilizer supplied by the fertilizer supply system 78 may be liquid fertilizer, powder fertilizer, or granular fertilizer. Furthermore, the plant growing device 1D has a water supply system 79. The water supply system 79 periodically supplies water to the culture soil 76 in the cultivation tank 72.

[0074] Like the plant growing device 1B of the third embodiment (FIG. 9), the plant growing device 1D has a remaining fertilizer amount measuring device 60. The remaining fertilizer amount measuring device 60 measures the amount of fertilizer remaining in a sample 61 taken from a plant 200 being grown in the cultivation unit 2. The amount of fertilizer calculated by remaining fertilizer amount calculation unit 60b of remaining fertilizer amount measuring device 60 is notified to environmental control device 42. As in the third embodiment, environmental control device 42 controls at least one of air conditioning system 20, light emission control device 44, fertilizer supply system 78, and water supply system 79 when the rate of decrease in the amount of fertilizer within a set period is greater than a threshold value based on the change in the measured amount of fertilizer. As in the first embodiment, the environmental control device 42 may control the light-emitting control device 44 to at least one of reducing the amount of light emitted by the artificial light Li, shortening the irradiation time of the artificial light Li, and reducing the blue wavelength region of the artificial light Li. Instead of or in addition to the above-mentioned control of the light-emitting control device 44, the environmental control device 42 may control the air-conditioning system 20 to reduce at least one of the temperature in the cultivation space 30 and the concentration of CO2 in the air. Instead of or in addition to the control of the light-emitting control device 44 and / or the air-conditioning system 20, the environmental control device 42 may control the fertilizer supply system 78 to reduce the amount of top dressing. Instead of, or in addition to, controlling the light control device 44, the air conditioning system 20 and / or the fertilizer supply system 78, the environmental control device 42 may control the water supply system 79 to reduce the amount of water supplied to the soil 76. According to this embodiment, if the rate of decrease in the amount of fertilizer in a sample collected from a plant within a set period of time is greater than a threshold, the growing environment of the plant can be changed to an environment that suppresses the plant's photosynthesis.

[0075] 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.

[0076] For example, in the above embodiment, when the rate of decrease in the measured amount corresponds to the seed enlargement stage of the plant, the environmental control device 42 controls the plant growth environment to an environment that suppresses photosynthesis. However, when the rate of decrease in the measured amount corresponds to the maturity stage of the plant, the environmental control device 42 may control the plant growth environment to an environment that suppresses photosynthesis. Even if photosynthesis is suppressed in the maturity stage, the yield of the seeds or rhizomes of the plant is not reduced, and costs can be reduced.

[0077] The fertilizer absorption amount calculation unit 40c, the plant fertilizer concentration calculation unit 50b, the remaining fertilizer amount calculation unit 60b, the plant sugar content calculation unit 70b, and the environmental control device 42 are not limited to a computer processor. All or part of these may be executed by hardware instead of a processor, or may be executed by a programmable logic device such as a field programmable gate array (FPGA) or a digital signal processor (DSP). The above embodiments may be combined unless they are inconsistent.

[0078] 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 growing space with artificial light; A cultivation tank that contains a liquid fertilizer, which is a nutrient solution containing fertilizer to be given to the plant, and in which at least the roots of the plant are placed; A measuring device for repeatedly measuring an amount corresponding to the amount of fertilizer absorbed by the plant; and an environmental control device that controls the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the amount measured by the measuring device within a set period is greater than a threshold value. A plant growing device characterized by the above.

[0079] Clause 2. The measuring device has a liquid volume sensor that repeatedly measures the amount of the liquid fertilizer supplied to the cultivation tank, and a calculation unit that repeatedly calculates the amount from at least the measurement result of the liquid volume sensor, When a rate of decrease in the amount within a set period is greater than a threshold, the environmental control device controls the growing environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. 2. A plant growing device according to claim 1, characterized in that In this case, the amount of fertilizer absorbed or an amount corresponding to the amount of fertilizer absorbed is calculated from the change in the amount of liquid fertilizer, and if the rate of decrease in the amount within a set period is greater than a threshold value, the plant's growing environment can be changed to one that suppresses plant photosynthesis.

[0080] Clause 3. The measuring device has a sensor that repeatedly measures an electrical characteristic corresponding to a fertilizer concentration of a liquid flowing through the plant or an individual plant of the same variety as the plant grown in the same environment for the same period as the plant, When the rate of decrease in the fertilizer concentration within a set period is greater than a threshold value, the environmental control device controls the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. 2. A plant growing device according to claim 1, characterized in that In this case, if the rate of decrease in the fertilizer concentration of the liquid actually flowing through the plant within a set period is greater than a threshold value, the plant's growing environment can be changed to one that suppresses plant photosynthesis.

[0081] Clause 4. The measuring device repeatedly measures an electrical characteristic corresponding to the amount of fertilizer remaining in samples taken from the plant or from individual plants of the same variety as the plant grown in the same environment for the same period of time as the plant; When a rate of decrease in the amount of fertilizer within a set period is greater than a threshold, the environmental control device controls the growing environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. 2. A plant growing device according to claim 1, characterized in that In this case, if the rate of decrease in the amount of fertilizer in a sample collected from a plant within a set period is greater than a threshold, the growing environment of the plant can be changed to one that suppresses photosynthesis of the plant.

[0082] Article 5. 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 growing space with artificial light; A cultivation tank in which at least the roots of the plant are placed; a measuring device for non-destructively and repeatedly measuring an electrical property corresponding to the sugar concentration of the liquid in the plant tissue; and an environmental control device that controls the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the concentration of the sugar within a set period is greater than a threshold value. A plant growing device characterized by the above. In this case, if the rate of decrease in the sugar concentration of the liquid actually flowing within the plant within a set period is greater than a threshold value, the plant's growing environment can be changed to one that suppresses the plant's photosynthesis.

[0083] Article 6. 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 growing space with artificial light; A cultivation tank in which at least the roots of the plant are placed; a measuring device for repeatedly measuring an electrical characteristic corresponding to the amount of fertilizer remaining in a sample taken from the plant or from an individual plant of the same variety as the plant grown in the same environment for the same period as the plant; and an environmental control device that controls the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the amount of the fertilizer within a set period is greater than a threshold value. A plant growing device characterized by the above. In this case, if the rate of decrease in the amount of fertilizer in a sample collected from a plant within a set period is greater than a threshold, the growing environment of the plant can be changed to one that suppresses photosynthesis of the plant.

[0084] Clause 7. The environmental control device controls the growth environment of the plant to change it to an environment that suppresses the photosynthesis of the plant, and performs at least one of reducing the amount of light emitted by the artificial light, shortening the irradiation time of the artificial light, and reducing the blue wavelength region of the artificial light. 7. A plant growing device according to any one of clauses 1 to 6, characterized in that The reduction in the amount of light emitted can reduce costs. Also, the reduction in the irradiation time can reduce costs.

[0085] Clause 8. The environmental control device controls the growth environment of the plant to change it to an environment that suppresses photosynthesis of the plant, thereby lowering the temperature in the growth space. 8. A plant growing device according to any one of clauses 1 to 7, characterized in that In this case, lower temperatures can reduce costs.

[0086] Clause 9. The environmental control device controls the growth environment of the plant to change it to an environment that suppresses the photosynthesis of the plant, thereby reducing the carbon dioxide concentration in the air in the growth space. 9. A plant growing device according to any one of clauses 1 to 8, characterized in that In this case, the reduction in carbon dioxide concentration can reduce costs.

[0087] Clause 10. The environmental control device controls the growth environment of the plant to an environment that suppresses the photosynthesis of the plant, thereby reducing the amount of top dressing. 10. A plant growing device according to any one of clauses 1 to 9, characterized in that In this case, costs can be reduced by reducing the amount of top dressing.

[0088] Clause 11. The at least one light source panel irradiates artificial light from the side onto the plurality of plants. 11. A plant growing device according to any one of clauses 1 to 10, characterized in that In this case, artificial light can be supplied evenly to each individual plant, thereby suppressing variation in growth among individual plants.

[0089] Article 12. A method for growing plants using artificial light, comprising: Irradiating a space for growing the plant with artificial light; Supplying a nutrient solution containing fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; Repeatedly measuring the amount of fertilizer absorbed by the plant; and when a rate of decrease in the measured amount within a set period is greater than a threshold, controlling the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. A method for growing plants comprising the steps of:

[0090] Article 13. A method for growing plants using artificial light, comprising: Irradiating a space for growing the plant with artificial light; Supplying a fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; repeatedly measuring an electrical property corresponding to a sugar concentration of a liquid in said plant tissue in a non-destructive manner; and when a rate of decrease in the concentration of the sugar within a set period is greater than a threshold, controlling the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. A method for growing plants comprising the steps of:

[0091] Article 14. A method for growing plants using artificial light, comprising: Irradiating a space for growing the plant with artificial light; Supplying a fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; Repeatedly measuring an electrical characteristic corresponding to the amount of fertilizer remaining in samples taken from the plant or from individual plants of the same variety as the plant grown in the same environment for the same period of time as the plant; and when a rate of decrease in the amount of fertilizer within a set period is greater than a threshold, controlling the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. A method for growing plants comprising the steps of: [Explanation of symbols]

[0092] 1, 1A, 1B, 1C, 1D...Plant growing device, 2, 2A...Cultivation unit, 12...Cultivation tank, 16...Nutrient solution, 18...Nutrient solution supply system, 20...Air conditioning system, 200...Plant, 30...Cultivation space, 32...Light source panel, 40...Nutrient absorption amount measuring device, 42...Environment control device, 40a...Sensor, 40b...Liquid volume sensor, 40c...Nutrient absorption amount calculation unit, 44...Light emission control device, 50...In-plant fertilizer concentration measuring device, 50a...Sensor, 50b...In-plant fertilizer concentration calculation unit, 60...Residual fertilizer amount measuring device, 60a...Sensor, 60b...Residual fertilizer amount calculation unit, 61...Sample, 72...Cultivation tank, 76...Soil, 78...Fertilizer supply system, 79...Water supply system, 70...In-plant sugar content measuring device, 70a...Sensor, 70b...In-plant sugar content calculation unit, Li...Artificial light

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 growing space with artificial light; A cultivation tank that contains a liquid fertilizer, which is a nutrient solution containing fertilizer to be given to the plant, and in which at least the roots of the plant are placed; A measuring device for repeatedly measuring an amount corresponding to the amount of fertilizer absorbed by the plant; and an environmental control device that controls the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the amount measured by the measuring device within a set period is greater than a threshold value. A plant growing device characterized by the above.

2. The measuring device has a liquid amount sensor that repeatedly measures the amount of the liquid fertilizer supplied to the cultivation tank, and a calculation unit that repeatedly calculates the amount from at least the measurement result of the liquid amount sensor, When a rate of decrease in the amount within a set period is greater than a threshold, the environmental control device controls the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant.

2. The plant growing device according to claim 1 .

3. the measuring device has a sensor that repeatedly measures an electrical characteristic corresponding to a fertilizer concentration of a liquid flowing through the plant or an individual plant of the same variety as the plant that has been grown in the same environment for the same period as the plant, When the rate of decrease in the fertilizer concentration within a set period is greater than a threshold value, the environmental control device controls the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant.

2. The plant growing device according to claim 1 .

4. the measuring device repeatedly measures an electrical characteristic corresponding to the amount of fertilizer remaining in a sample taken from the plant or from an individual plant of the same variety as the plant grown in the same environment for the same period as the plant; When a rate of decrease in the amount of fertilizer within a set period is greater than a threshold, the environmental control device controls the growing environment of the plant to be changed to an environment that suppresses photosynthesis of the plant.

2. The plant growing device according to claim 1 .

5. 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 growing space with artificial light; A cultivation tank in which at least the roots of the plant are placed; a measuring device for non-destructively and repeatedly measuring an electrical property corresponding to the sugar concentration of the liquid in the plant tissue; and an environmental control device that controls the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the concentration of the sugar within a set period is greater than a threshold value. A plant growing device characterized by the above.

6. 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 growing space with artificial light; A cultivation tank in which at least the roots of the plant are placed; a measuring device for repeatedly measuring an electrical characteristic corresponding to the amount of fertilizer remaining in a sample taken from the plant or from an individual plant of the same variety as the plant grown in the same environment for the same period as the plant; and an environmental control device that controls the growing environment of the plant to change to an environment that suppresses photosynthesis of the plant when a rate of decrease in the amount of the fertilizer within a set period is greater than a threshold value. A plant growing device characterized by the above.

7. The environmental control device controls the growth environment of the plant to change to an environment that suppresses photosynthesis of the plant, and performs at least one of reducing the amount of light emitted by the artificial light, shortening the irradiation time of the artificial light, and reducing the blue wavelength region of the artificial light.

7. The plant-growing device according to claim 1,

8. The environmental control device controls the growth environment of the plant to change the growth environment to an environment that suppresses photosynthesis of the plant, thereby lowering the temperature in the growth space.

7. The plant-growing device according to claim 1,

9. The environmental control device controls the plant growth environment to change the environment to one that suppresses photosynthesis of the plant, thereby reducing the carbon dioxide concentration in the air in the growth space.

7. The plant-growing device according to claim 1,

10. The environmental control device controls the growth environment of the plant to change to an environment that suppresses photosynthesis of the plant, thereby reducing the amount of top dressing.

7. The plant-growing device according to claim 1,

11. The at least one light source panel irradiates the plurality of plants with artificial light from a side.

7. The plant-growing device according to claim 1,

12. A method for growing plants using artificial light, comprising: Irradiating a growth space in which the plant is grown with artificial light; Supplying a nutrient solution containing fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; Repeatedly measuring the amount of fertilizer absorbed by the plant; and when a rate of decrease in the measured amount within a set period is greater than a threshold, controlling the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. A method for growing plants comprising the steps of:

13. A method for growing plants using artificial light, comprising: Irradiating a growth space in which the plant is grown with artificial light; Supplying a fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; non-destructively and repeatedly measuring an electrical property corresponding to a sugar concentration of a liquid in said plant tissue; and when a rate of decrease in the concentration of the sugar within a set period is greater than a threshold, controlling the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. A method for growing plants comprising the steps of:

14. A method for growing plants using artificial light, comprising: Irradiating a growth space in which the plant is grown with artificial light; Supplying a fertilizer to be given to the plant to a cultivation tank in which at least the roots of the plant are placed; Repeatedly measuring an electrical characteristic corresponding to the amount of fertilizer remaining in samples taken from the plant or from individual plants of the same variety as the plant grown in the same environment for the same period of time as the plant; and when a rate of decrease in the amount of fertilizer within a set period is greater than a threshold, controlling the growth environment of the plant to be changed to an environment that suppresses photosynthesis of the plant. A method for growing plants comprising the steps of:

Images