Hydroponic cultivation device and hydroponic cultivation method

Abstract

To provide a hydroponic cultivation device and a hydroponic cultivation method that enable optimal lighting and liquid fertilizer supply for efficient plant growth.SOLUTION: The present invention provides a hydroponic cultivation device, comprising: an LED light source for hydroponic cultivation that combines a white LED having a light intensity in the 470 to 600 nm wavelength range of 75% or less of the peak light intensity of blue light emitted in the 440 to 460 nm wavelength range, a red LED emitting in the 650 to 670 nm wavelength range, a near-ultraviolet LED emitting in the 400 to 410 nm wavelength range, and a near-infrared LED emitting in the 730 to 740 nm wavelength range; a water level control mechanism for adjusting the level of liquid fertilizer relative to the roots of a cultivated plant; and a water flow control mechanism capable of intermittently applying a flow of liquid fertilizer to the roots.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hydroponic cultivation apparatus and a hydroponic cultivation method used for hydroponic cultivation of plants, particularly vegetables such as leafy vegetables, fruit vegetables, and herbs. [Background technology]

[0002] In the field of hydroponic plant cultivation, technological development is underway to create optimal light for plant growth using artificial light sources such as LED lighting, thereby growing plants efficiently. By promoting plant growth, it is possible to shorten the cultivation period, increase the harvest turnover rate, and increase the yield obtained in the same period. For this reason, there has been a demand for a hydroponic cultivation device and method that can irradiate light with the required wavelength with the optimal spectral distribution depending on the plant variety and growth stage, and can also supply liquid fertilizer to promote plant growth.

[0003] Therefore, the following LED lighting devices for hydroponic cultivation have been proposed. Patent Document 1 discloses an LED lighting device for plant cultivation that includes a white LED having an emission spectrum that is continuous from at least 450 to 700 nm, a red LED having at least one peak in the wavelength range of 600 to 700 nm, a far-infrared LED having at least one peak in the wavelength range of 700 to 800 nm, and an ultraviolet LED having at least one peak in the wavelength range of 350 to 425 nm. It also discloses a switch for turning on / off the power supply to each of these single-color LEDs. However, the document only shows the emission spectrum of the light sources that can be irradiated by combining these four light sources, and does not disclose any technology for improving the effectiveness of the hydroponic cultivation device as a whole, including the supply of liquid fertilizer.

[0004] Patent Document 2 discloses an LED lighting device for plant cultivation that is composed of a white LED with a color temperature of 4500K, an ultraviolet LED with a peak wavelength of 380nm, a red LED with a peak wavelength of 660nm, and a far-red LED with a peak wavelength of 730nm. However, the light emission intensity of each LED is fixedly determined by the number of LED chips arranged, and there is a problem in that it is difficult to flexibly adjust the light emission spectrum according to the type of plant or the growth stage.

[0005] Patent Document 3 discloses a hydroponic cultivation device and method that includes a seedbed with a characteristic shape, a cultivation board that houses the seedbed, and a cultivation tub on which the cultivation board is placed, the cultivation tub is connected by a water supply and drainage pipe, and can alternate between full water and dry water conditions. However, there is no particular limitation on the light source that irradiates light, and there is no disclosure of irradiation of light that is effective for plant growth.

[0006] These prior art technologies had problems in that the emission wavelength range and emission intensity of each LED light source that constitutes the lighting necessary for plant growth were not necessarily optimized, and the method of supplying liquid fertilizer that promotes the secretion of growth hormones necessary for promoting plant growth was not optimized, resulting in high growth efficiency. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2021-119743 A [Patent Document 2] Patent Publication No. 2021-058141 [Patent Document 3] JP 2019-075998 A Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a hydroponic cultivation apparatus and a hydroponic cultivation method that enable the supply of optimal illumination light and liquid fertilizer for efficient plant growth. [Means for solving the problem]

[0009] The present invention is characterized by comprising an LED light source for hydroponic cultivation that combines a white LED whose light intensity in the 470-600 nm wavelength region is 75% or less of the peak light intensity of blue light emitted in the 440-460 nm wavelength range, a red LED that emits light in the 650-670 nm wavelength range, a near-ultraviolet LED that emits light in the 400-410 nm wavelength range, and a near-infrared LED that emits light in the 730-740 nm wavelength range, a water level control mechanism that adjusts the level of liquid fertilizer relative to the roots of a cultivated plant, and a water flow control mechanism that can intermittently provide a flow of liquid fertilizer to the roots.

[0010] The LED light source for hydroponic cultivation is characterized in that the emission intensity ratio of the red region to the blue region is 2.0 or more, the emission intensity ratio of the near-ultraviolet region to the blue region is 0.2 to 0.4, and the emission intensity ratio of the near-infrared region to the blue region is 0.7 to 0.9.

[0011] The LED lighting device in which the LED light source for hydroponic cultivation is arranged is configured so that the DC power supply for the LED light source can be separated.

[0012] A single DC power supply for the LED light source for hydroponic cultivation is characterized in that multiple LED lighting devices in one cultivation area are driven collectively.

[0013] The LED light source for hydroponic cultivation is characterized in that a dimming mechanism including an on / off function is added to the DC power supply of the LED light source for hydroponic cultivation.

[0014] The hydroponic cultivation method uses a hydroponic cultivation device equipped with an LED light source for hydroponic cultivation that combines a white LED with a light intensity in the 470-600 nm wavelength range that is 75% or less of the peak light intensity of blue light emitted in the 440-460 nm wavelength range, a red LED that emits in the 650-670 nm wavelength range, a near-ultraviolet LED that emits in the 400-410 nm wavelength range, and a near-infrared LED that emits in the 730-740 nm wavelength range, a water level control mechanism that adjusts the level of liquid fertilizer relative to the roots of a cultivated plant, and a water flow control mechanism that can intermittently provide a flow of liquid fertilizer to the roots, and is characterized in that during light irradiation by the LED light source for hydroponic cultivation, a drought state in which only the tips of the roots are immersed in the liquid fertilizer by the water level control mechanism and a running water state in which the roots are wetted by the liquid fertilizer provided by the water flow control mechanism and the water flow physically stimulates the roots.

[0015] The liquid fertilizer is intermittently applied once every 30 minutes or less, and the duration of each application of the liquid fertilizer flow is 1 to 10 minutes. Effect of the Invention

[0016] According to the present invention, it is possible to provide a hydroponic cultivation device and a hydroponic cultivation method that can promote plant growth by providing lighting with optimized wavelength components and luminous intensity required for plant growth while intermittently stimulating the roots of the plants with a water flow to activate growth hormone secretion. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram showing an example of an emission spectrum of an LED light source used in the hydroponic cultivation device according to the present invention. [Diagram 2] FIG. 2 is a diagram showing the configuration of a DC power supply for an LED light source used in the hydroponic cultivation device according to the present invention. [Diagram 3] FIG. 13 is a diagram showing growth curves of plants cultivated using the hydroponic cultivation device according to the present invention when illumination was performed with different configurations of LED light sources. [Figure 4]1 is a diagram illustrating an embodiment of a water flow control mechanism used in a hydroponic cultivation apparatus according to the present invention. FIG. [Diagram 5] 11A to 11C are diagrams illustrating another embodiment of a water flow control mechanism used in a hydroponic cultivation device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a hydroponic cultivation apparatus and a hydroponic cultivation method according to an embodiment of the present invention will be described.

[0019] Plants grow by absorbing light through the photoreceptor chlorophyll present in the chloroplasts, taking in carbon dioxide and water, and converting them into sugars through photosynthesis. Photosynthesis by chlorophyll mainly uses light in the wavelength range of 400 to 700 nm, but since it has absorption peaks in the red region around 660 nm and the blue region around 450 nm, red light and blue light are particularly effective for photosynthesis.

[0020] For this reason, the LED light source of the hydroponic cultivation device of the present invention has as its basic components a white LED that emits less wavelength components other than the red and blue light effective for photosynthesis in its emission spectrum, and whose light intensity in the wavelength range of 470 to 600 nm is 75% or less of the peak light intensity of blue light emitted in the wavelength range of 440 to 460 nm, and a red LED that has an emission spectrum in the wavelength range of 650 to 670 nm.

[0021] Meanwhile, in addition to chlorophyll, which is involved in photosynthesis, plants have photoreceptors such as phytochromes, cryptochromes, and phototropins that collect light environment information necessary for plant growth. It is known that the light to which each photoreceptor responds activates the secretion of hormones, which play an important role in plant growth.

[0022] For example, stimulating the roots can cause the plant to activate its own secretion of growth hormone, further promoting growth. Assuming that the source of growth hormone is produced in the leaves, in addition to the LED light source consisting of the white LED and red LED described above, we investigated the effects of LEDs with various emission wavelength ranges on plant growth. As a result, we confirmed that plant growth was significantly promoted by adding, for example, a near-ultraviolet LED with an emission peak at 406 nm and a near-infrared LED with an emission peak at 735 nm.

[0023] Based on these experimental results, it is believed that near-ultraviolet and near-infrared light also play an important role in plant growth, similar to photosynthesis using blue and red light, and as such, in addition to the basic components consisting of the white LED and red LED described above, a near-ultraviolet LED having an emission spectrum in the wavelength range of 400 to 410 nm and a near-infrared LED having an emission spectrum in the wavelength range of 730 to 740 nm are added as components to the LED light source of the hydroponic cultivation device of the present invention.

[0024] With regard to the emission intensities of the emission peaks, it is preferable that the emission intensity ratio of the emission peak in the red region to the emission peak in the blue region is 2.0 or more, the emission intensity ratio of the emission peak in the near-ultraviolet region to the emission peak in the blue region is 0.2 to 0.4, and the emission intensity ratio of the emission peak in the near-infrared region to the emission peak in the blue region is 0.7 to 0.9.

[0025] As an example of the embodiment of the present invention, a white LED having a light intensity in the wavelength range of 470 nm to 600 nm that is 75% or less of the peak light intensity of blue light emitted at 450 nm, a red LED having an emission peak at 660 nm, a near-ultraviolet LED having a peak wavelength of 406 nm, and a near-infrared LED having a peak wavelength of 735 nm are used to configure an LED light source for hydroponic cultivation, which is composed of one or more of each LED. The emission spectrum is shown in Figure 1.

[0026] The emission spectrum 1 of the LED light source used in the hydroponic cultivation device according to the present invention will be described with reference to Fig. 1. The emission spectrum 1 of the LED light source has a near-ultraviolet peak 11 due to the near-ultraviolet LED, a blue peak 12 due to the white LED, a red peak 13 which is a combination of the red peaks due to the white LED and the red LED, and a near-infrared peak 14 due to the near-infrared LED.

[0027] The magnitude of each emission peak was adjusted so that the emission intensity ratio of the red light peak at 660 nm to the blue light peak at 450 nm was 2.5, the emission intensity ratio of the entire region of 470 to 600 nm of the white LED to the blue light peak at 450 nm was 0.7 or less, the emission intensity ratio of the near-ultraviolet light peak at 406 nm to the blue light peak at 450 nm was 0.3, and the emission intensity ratio of the near-infrared light peak at 735 nm to the blue light peak at 450 nm was 0.7.

[0028] Although LED lighting is generally considered to have a long lifespan, the cultivation environment of hydroponics and plant factories is harsh for LED lighting fixtures. Even if the LED chip itself has a long lifespan, malfunctions in the DC power supply built into the lighting fixtures can prevent the LED's inherent long lifespan from being utilized. More specifically, electrolytic capacitors are generally used as components to obtain DC from commercial AC power sources, but electrolytic capacitors are vulnerable to heat and humidity and have an extremely short lifespan compared to LED chips. Because the hydroponic cultivation environment is harsh for electrical components, if LED lighting fixtures have a short lifespan, it will lead to higher cultivation costs, as the LED lighting fixtures make up a high proportion of the cost of the cultivation equipment.

[0029] Generally, LED lighting fixtures are constructed with an LED module containing multiple LED chips and a DC power supply integrated inside the fixture, but the above problems can be solved by storing the DC power supply as an external power supply for the fixture in a highly moisture-proof package. This eliminates the effects of heat generated by the LEDs and the effects of high humidity in the cultivation equipment, extends the lifespan of both the LED lighting fixture and the DC power supply, and prevents an increase in cultivation costs. Another advantage is that in the unlikely event that the DC power supply breaks down, it is possible to replace only the DC power supply, rather than having to replace the entire expensive LED lighting fixture.

[0030] FIG. 2 shows a block diagram of a DC power supply used for the LED light source of the hydroponic cultivation device according to the present invention. A commercial AC power source 21 supplies DC power to an LED lighting device 25 modularized by arranging at least one or more types of LEDs so as to obtain an emission spectrum as shown in Fig. 1 through a timer 22 that sets light / dark times to adjust the circadian rhythm of plants and an AC / DC converter 23, and one cultivation area 26 in which multiple lighting devices are arranged is driven by one DC power source. In the example of Fig. 2, six LED lighting devices 25 are arranged in one cultivation area 26. Furthermore, a dimming function 24 including an on / off function, which will be described later, is arranged between the AC / DC converter 23 and the LED lighting device 25.

[0031] In cultivation, the distance between the leaves and the lighting fixtures decreases as the plant grows, and the light intensity felt by the leaves increases with growth. For example, if the light intensity is adjusted in the early stages of growth, i.e. when the seedlings are short, the light intensity may be too strong in the later stages of growth. At that time, growth disorders such as tip burn, in which the tips of the leaves turn black, may occur. Therefore, a dimming function including an on / off function was added to the DC power supply shown in Figure 2. This makes it possible to control the on / off and dimming of each LED, and by turning off unnecessary types of LEDs or dimming to the optimal light intensity according to growth, it is possible to reduce power consumption and prevent growth disorders, thereby reducing cultivation costs by reducing power consumption and improving cultivation yields.

[0032] The LED light source of the hydroponic cultivation device according to the present invention can be used at all stages of the growth of cultivated plants. However, in general, only water and temperature are important during the germination stage, and light is hardly required, so among the LED light sources of the hydroponic cultivation device according to the present invention, it is possible to irradiate only the white LED and turn off the other LED light sources by using the on / off function of the dimming function of the DC power supply. This makes it possible to achieve the effect of saving power by not turning on the LED light sources other than the white LED.

[0033] In general, LED light sources can be provided with a dimming function by various methods. As an example of a means for realizing the dimming function, it is possible to adjust the dimming by changing the switching duty of the switching power supply. Normally, as described above, the DC power supply is also arranged inside the lighting fixture, and therefore, when the output of the light source is large, the components of the switching power supply also become large, which is a problem in that the entire lighting fixture becomes large. However, in the LED light source used in the hydroponic cultivation device according to the present invention, the DC power supply is configured to be independent and external, so that the lighting fixture is not restricted in size by the power supply.

[0034] A typical method of supplying and circulating liquid fertilizer in a hydroponic cultivation system is to circulate the liquid fertilizer through a configuration of a liquid fertilizer storage section, a water supply and drainage channel, cultivation containers, etc. For example, a method is used in which the cultivation containers are connected using a siphon and an overflow pipe, and excess liquid fertilizer in one cultivation container is circulated to the other cultivation containers.

[0035] The hydroponic cultivation method of the present invention is characterized by a cultivation method in which light with a wavelength effective for plant growth is irradiated while at the same time intermittently providing a water flow to the roots to stimulate the roots and promote the secretion of growth hormones, and is characterized by a cultivation method in which a drought state in which only the tips of the roots are immersed in liquid fertilizer is repeated with a running water state in which the roots are wetted with liquid fertilizer and at the same time the water flow physically stimulates the roots.

[0036] In drought conditions, when only the tips of the roots are submerged in liquid fertilizer and the rest of the plant is exposed to the air and dry, the roots tend to grow more easily than usual, increasing the efficiency of water and fertilizer absorption. In addition, when the aerial roots come into direct contact with the air, they take in oxygen directly from the air, improving the efficiency of oxygen absorption.

[0037] On the other hand, by intermittently wetting the roots with liquid fertilizer and shaking them with a water current, the tissue at the base that secretes growth hormone is stimulated, promoting the secretion of growth hormone. However, without near-ultraviolet and near-infrared light, which are necessary to create the source material for growth hormone, the secretion effect of growth hormone is small, so the stimulation of the roots with the water current of liquid fertilizer and the irradiation with near-ultraviolet and near-infrared light must be done at the same time.

[0038] The hydroponic cultivation device is provided with a water level control mechanism that controls the distance between the roots and the liquid fertilizer water level to achieve a drought state in which only the tips of the roots are in contact with the liquid level. One example of this water level control mechanism is a method of installing an overflow pipe or siphon and adjusting the water level by the height of the drainage outlet, but there are also other methods, such as increasing or decreasing the amount of liquid fertilizer supplied to raise or lower the liquid level, or raising or lowering the cultivation board on which the cultivated plants are loaded relative to the liquid level, and the method is not limited to these means.

[0039] The water flow control mechanism for providing a water flow of liquid fertilizer to the roots may be, but is not limited to, a method of sending a water flow from a water flow pump to the cultivation container at a predetermined time interval, a method of arranging a liquid fertilizer pipe having a liquid fertilizer outlet near the roots of each cultivated plant and sending the liquid at a predetermined time interval and emitting a water flow from the outlet, or a method of utilizing the increase or decrease in water level due to the inflow and outflow of liquid fertilizer between other cultivation containers through an overflow pipe or siphon. In any case, the state in which a water flow is generated is considered to be a flowing water state, even if the water level of liquid fertilizer increases or decreases due to the inflow and outflow of liquid fertilizer, or even if the water level is kept constant by the water level control mechanism.

[0040] In the hydroponic cultivation method according to the present invention, the frequency of the intermittent water flow of the liquid fertilizer is not particularly limited, but excessive water flow may damage the roots. Therefore, the strength of the water flow is set to a level that can physically stimulate the tissues secreting the growth hormone in the roots, that is, a water flow that is strong enough to shake the roots. The frequency of the water flow is counted as one cycle of inflow-outflow of the liquid fertilizer, that is, one cycle from a drought state to a full water state and back to a drought state, or one cycle from a full water state to a drought state and back to a full water state. The duration of the water flow is defined as the total time of the time when the water level of the liquid fertilizer increases due to inflow through an overflow pipe or a siphon, or the time when the water level continues to flow into the overflow pipe or the siphon or the time when the water level continues to flow by the water pump even after the water level becomes constant in the full water state, and the time when the liquid fertilizer flows out through the overflow pipe or the siphon and the water level decreases. When the water flow period and duration are defined as above, the water flow frequency is preferably once every 30 minutes or less, and the duration of each water flow is preferably in the range of 1 to 10 minutes.

[0041] In the present invention, the type of plant is not particularly limited, but it is preferable to apply it to leafy vegetables, fruit vegetables, herbs, grains, etc. Examples of vegetables include lettuce such as leaf lettuce, garden lettuce, curl lettuce, lamb's lettuce, romaine lettuce, endive, lollo rossa, arugula lettuce, frill lettuce, green leaf, and lettuce, Asteraceae vegetables such as chrysanthemum, Morning Glory family vegetables such as spinach, and Rosaceae vegetables such as strawberry, but are not limited to these.

[0042] Example 1 As an example of the hydroponic cultivation apparatus according to the present invention, a hydroponic cultivation apparatus 3 shown in FIG. 4 was used to cultivate lettuce, which is a type of green leaf lettuce. In this embodiment, overflow pipe 40 and siphon 41 used to discharge liquid fertilizer to other cultivation containers provided in cultivation container 31, and overflow pipe 42 and siphon 43 used to supply liquid fertilizer from another cultivation container to cultivation container 31, were used as a water level control mechanism and a water flow control mechanism, and repeated switching was performed between a water flow state in which the roots were immersed in liquid fertilizer and a drought state in which only the tips of the roots were immersed in liquid fertilizer. The water flows once every 30 minutes, with each flow lasting 10 minutes. Of the LED light sources of the present invention, which are used in the LED lighting fixture 25 used for light irradiation and whose emission spectrum is shown in Figure 1, Figure 3 shows cultivation curves for the cases where only white LEDs and red LEDs are used, where near-ultraviolet LEDs are also added, and where near-infrared LEDs are also added. The horizontal axis is the number of days of cultivation from sowing, and the vertical axis is the weight per plant. The light intensity on the cultivation board surface at this time was 120 μmol m in photosynthetically active photon flux density when all white LEDs, red LEDs, near-ultraviolet LEDs, and near-infrared LEDs were combined. -2 ·s -1 In addition, the timer 22 was set so that the light time was 85% and the dark time was 15%.

[0043] Specifically, by connecting the cultivation container 31 with an overflow pipe 40 and a siphon 41, excess liquid fertilizer in the cultivation container 31 flows out through the overflow pipe 40 and the siphon 41, and similarly, liquid fertilizer from other cultivation containers flows in through the overflow pipe 42 and the siphon 43. When the water level of the liquid fertilizer increases, drainage begins when the water level reaches the drain outlet 400 of the overflow pipe 40, and the water level does not rise any further, so the overflow pipe 40 functions as a water level control mechanism for the water level 36 in the full water state. At this time, the water level of the roots 34 of the sprout 33 supported on the cultivation board 35 is set so that the entire roots are immersed in the liquid fertilizer. The valve 44 provided on the siphon 41 functions as a part of the water flow control mechanism, and when the valve 44 is opened, drainage begins through the drain outlet 410 of the siphon 41, causing the water level to drop, and when the water level reaches the drain outlet 410 of the siphon 41, drainage stops, so that the valve 44 functions as a water level control mechanism for the water level 37 in the drought state in which only the tips of the roots are immersed in the liquid fertilizer. The height of the drainage openings of the overflow pipe 40 and the siphon 41 can be adjusted as appropriate.

[0044] In this way, while liquid fertilizer flows in and out through the overflow pipe 40 and the siphon 41, a water current is generated by the movement of liquid fertilizer inside the cultivation container 31, shaking the roots of the cultivated plants and providing a physical stimulus. In this embodiment, the frequency of water currents due to the inflow of liquid fertilizer from a drought state to a full water state, water currents in the full water state, and water currents due to the outflow of liquid fertilizer from a full water state to a drought state occurred once every 30 minutes. The duration of the water currents due to the inflow and outflow of liquid fertilizer was adjusted to 10 minutes.

[0045] Example 2 As another embodiment of the present invention, lettuce was cultivated using a hydroponic cultivation device 30 according to the present invention shown in Fig. 5. The LED lighting device 25 used and the light irradiation conditions were the same as those in Example 1. In the hydroponic cultivation device 30 shown in Fig. 5, overflow pipes 45, 46 were used as a water level control mechanism, and a liquid supply pipe 47 was used as a water flow control mechanism, and repeated switching was performed between a water flow state in which the entire roots were immersed in liquid fertilizer and a drought state in which only the tips of the roots were immersed in liquid fertilizer.

[0046] Specifically, by connecting the cultivation container 32 using two overflow pipes 45 and 46 with drainage outlets at different heights, excess liquid fertilizer in the cultivation container 32 flows out through the overflow pipes 45 and 46, functioning as a water level control mechanism, while the inflow of liquid fertilizer is supplied from the liquid supply pipe 47 using a water flow pump 49, and the strength of the water flow is adjusted by the flow rate of the water flow pump 49, so that the water flow control mechanism is functioned by the water flow pump 49. When the water level of the liquid fertilizer increases and reaches the drain outlet 450 of the overflow pipe 45, the water level does not rise any further, so that the overflow pipe 45 functions as a water level control mechanism for the full water level 36. When liquid fertilizer is introduced from the liquid supply pipe 47 using a water flow pump, the water flow continues to be applied to the roots 34 until the full water flowing water level 36 is reached, and even after the full water flowing water level 36 is reached, while the water level is kept constant by drainage from the overflow pipe drain outlet 450, the roots 34 of the cultivated plant are shaken and physically stimulated. When the valve 48 of the overflow pipe 46 is opened from a full water flowing state, the liquid fertilizer level drops to the position of the drain outlet 460 of the overflow pipe 46 and stops at the water level 37 in the drought state. In this example, the frequency of water flow caused by the inflow of liquid fertilizer from a drought state to a full water state, water flow in the full water state, and water flow caused by the outflow of liquid fertilizer from a full water state to a drought state was once every 30 minutes. The duration of water flow caused by the inflow and outflow of liquid fertilizer was adjusted to 10 minutes.

[0047] The results of Examples 1 and 2, in which lettuce was cultivated according to the present invention, are shown in Table 1, together with the results in the absence of intermittent water flow to the roots, which is a feature of the present invention.

[0048] [Table 1]

[0049] The light intensity of a typical plant factory using normal white LEDs is 200 μmol m -2 ·s -1 and more recently, 300 μmol m -2 ·s -1Under such conditions, in a typical plant factory, the cultivation speed is generally about 40 days from sowing, and one head of green leaf lettuce weighs 70 to 100 g.

[0050] In contrast, in the hydroponic cultivation method according to one embodiment of the present invention, the light intensity is 120 μmol m -2 ·s -1 Although the weight is about half that of a general plant factory, in the case of Example 1 with water flow, 90-110g per plant was obtained in 38 days with only white LED, 135-150g per plant was obtained in 38 days with red LED, 135-150g per plant was obtained in 34 days with near-ultraviolet LED, and 135-150g per plant was obtained in 30 days with near-infrared LED, and the growth rate was greatly improved by adding near-ultraviolet and near-infrared light in addition to blue and red. In the case of Example 2 with water flow, 100-120g per plant was obtained in 38 days with only white LED, 135-150g per plant was obtained in 36 days with red LED, 135-150g per plant was obtained in 32 days with near-ultraviolet LED, and 135-150g per plant was obtained in 28 days with near-infrared LED. The growth rate was greatly improved by adding near-ultraviolet and near-infrared light in addition to blue and red. When there was no water flow, the plants gained 70-90g in 40 days with only white LEDs, 90-110g with the addition of red LEDs, 100-120g with the addition of near-ultraviolet LEDs, and 100-120g with the addition of near-infrared LEDs. These results show that providing water flow to the roots promotes growth, with particularly notable effects being observed when near-ultraviolet and near-infrared light are being irradiated.

[0051] From the results in Table 1, when red LED light is added to white LED light, the presence of water flow causes root elongation and activation of the roots due to oxygen absorption by the aerial roots, which is thought to promote growth compared to when there is no water flow. Also, when red LED light and near-ultraviolet LED light are added to white LED light, growth is clearly promoted when there is water flow, which is thought to be the result of the near-ultraviolet LED light producing growth hormone source substances in the leaves, and the stimulation of the roots by the water flow promoting hormone secretion in the roots, which promotes growth. Furthermore, when red LED light, near-ultraviolet LED light, and near-infrared LED light are added to white LED light, the near-infrared light also produces growth hormone source substances, which promotes the secretion of growth hormone in the roots by the water flow, which is thought to be the result of further promoting growth. [Industrial Applicability]

[0052] The hydroponic cultivation device and hydroponic cultivation method of one embodiment of the present invention is capable of concentrating light in the wavelength range required for photosynthesis and photomorphogenesis in plants, thereby more effectively promoting plant growth. Furthermore, the intermittent water flow promotes the secretion of growth hormones in the roots, further promoting growth, thereby providing a hydroponic cultivation system with high cultivation efficiency and energy efficiency. [Explanation of symbols]

[0053] 1. Emission spectrum of the LED light source for the hydroponic cultivation device according to the present invention 11 Wavelength components of near-ultraviolet light produced by near-ultraviolet LED 12 Wavelength components of blue light from white LED 13 Red light wavelength components from a white light LED and red light wavelength components from a red LED 14 Wavelength components of near-infrared light emitted by near-infrared LED 2 Block diagram of a DC power supply for an LED light source for a hydroponic cultivation device according to the present invention 21 Commercial AC power supply 22 Timer 23 AC / DC converter 24 Dimming function including on / off function 25 LED lighting fixtures 26 One cultivation area 3. Hydroponic Cultivation Apparatus of Example 1 30 Hydroponic cultivation device of Example 2 31 Cultivation container of Example 1 32 Cultivation container of Example 2 33 Bud 34 Root 35 Cultivation Board 36 Water level when the water is full and flowing 37 Drought water level 40 Overflow pipe 41 Siphon 400 Overflow pipe drain 410 Siphon drain 42 Overflow pipes from other growing containers 43 Siphoning from other growing containers 44 Siphon Valve 45 Overflow pipe 1 46 Overflow pipe 2 450 Overflow pipe 1 drain 460 Overflow pipe 2 drain outlet 47 Liquid supply pipe 48 Overflow pipe 2 valve 49 Water Pump

Claims

1. an LED light source for hydroponic cultivation that combines a white LED having a light intensity in the 470-600 nm wavelength region that is 75% or less of the peak light intensity of blue light emitted in the 440-460 nm wavelength range, a red LED that emits light in the 650-670 nm wavelength range, a near-ultraviolet LED that emits light in the 400-410 nm wavelength range, and a near-infrared LED that emits light in the 730-740 nm wavelength range; A hydroponic cultivation device comprising: a water level control mechanism for adjusting the level of liquid fertilizer relative to the roots of cultivated plants; and a water flow control mechanism for intermittently applying a flow of liquid fertilizer to the roots.

2. The hydroponic cultivation device according to claim 1, characterized in that the emission intensity ratio of the red region to the blue region of the hydroponic cultivation LED light source is 2.0 or more, the emission intensity ratio of the near ultraviolet region to the blue region is 0.2 to 0.4, and the emission intensity ratio of the near infrared region to the blue region is 0.7 to 0.

9.

3. 3. The hydroponic cultivation device according to claim 1, wherein an LED lighting fixture in which the hydroponic cultivation LED light source is arranged is configured so that a DC power source for the LED light source can be separated from the LED lighting fixture.

4. 4. The hydroponic cultivation device according to claim 3, wherein a single DC power supply for the LED light source for hydroponic cultivation drives a plurality of the LED lighting devices in one cultivation area collectively.

5. 4. The hydroponic cultivation device according to claim 3, wherein a dimming function including an on / off function is added to a DC power supply of the LED light source for hydroponic cultivation.

6. an LED light source for hydroponic cultivation that combines a white LED having a light intensity in the 470-600 nm wavelength region that is 75% or less of the peak light intensity of blue light emitted in the 440-460 nm wavelength range, a red LED that emits light in the 650-670 nm wavelength range, a near-ultraviolet LED that emits light in the 400-410 nm wavelength range, and a near-infrared LED that emits light in the 730-740 nm wavelength range; In hydroponic cultivation using a hydroponic cultivation device having a water level control mechanism for adjusting the water level of liquid fertilizer relative to the roots of a cultivated plant and a water flow control mechanism capable of intermittently applying a water flow of liquid fertilizer to the roots, This hydroponic cultivation method is characterized in that, while light is irradiated by the hydroponic LED light source, a drought state in which only the tips of the roots are immersed in the liquid fertilizer by the water level control mechanism and a running water state in which the roots are wetted by a water flow of the liquid fertilizer by the water flow control mechanism, and at the same time, the water flow applies a physical stimulus to the roots.

7. The hydroponic cultivation method according to claim 6, characterized in that the frequency of intermittent application of the liquid fertilizer flow is once every 30 minutes or less, and the duration of each application of the liquid fertilizer flow is 1 to 10 minutes.

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