Aerosol hydroponics plant

Abstract

To provide a spray hydroponic cultivation plant and a method for spray hydroponic cultivation, which achieve spray hydroponic cultivation for promoting plant growth while using less fertilizer and water.SOLUTION: A spray hydroponics plant 1 comprises: a cultivation tank 2 for cultivating a plant P hydroponically, in which a support part 2b supports the plant P with the underground part of the plant P exposed in a container 2a; a spray head 43 that sprays a liquid to the underground part of the plant P; and a liquid supply path 42 that supplies the liquid to the spray head 43. The liquid is a plasma functional liquid L containing active species.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a spray hydroponics plan To and is related thereto.

Background Art

[0002] In recent years, technologies for applying plasma to plant cultivation have been studied. In particular, it is known that by introducing plasma-treated gas (plasma gas) into a liquid (solvent) and applying this liquid to hydroponics, plant growth can be promoted (see, for example, Patent Document 1). Also, it is known that spraying a dissolution solution containing active species generated by plasma treatment onto plants can sterilize pathogens, insects, etc. (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in hydroponics where a liquid containing liquid fertilizer is sprayed onto the roots of plants, there is a growing need to reduce the amount of liquid used to cut the economic cost in terms of expenses, reduce the adverse impact on the environment caused by liquid fertilizer, and promote plant growth.

[0005] Therefore, technical problems to be solved arise in order to realize spray hydroponics that promotes plant growth while reducing fertilizer and water, and the present invention aims to solve this problem

Means for Solving the Problems

[0006] To achieve the above objective, the spray hydroponic cultivation plant according to the present invention includes a cultivation tank for hydroponically cultivating plants, in which a support part supports the plants with the underground part of the plants exposed inside the container, and the underground part of the plants Medium department Plasma functional liquid containing active species A liquid injection unit that sprays the liquid, and the liquid injection unit Plasma functional liquid A liquid supply unit that supplies liquid, A plasma functional liquid manufacturing apparatus that produces the plasma functional liquid by introducing plasma gas generated from plasma generation gas into a solvent, Equipped with, The plasma functional liquid manufacturing apparatus comprises a first electrode to which a high-frequency voltage is applied, a second electrode made of a porous metal member positioned opposite the first electrode across a space and connected to earth, and a gas supply path for supplying plasma generating gas to the space; a plasma gas generation unit that generates plasma in the plasma generating gas in the space by applying a high-frequency voltage between the first electrode and the second electrode to generate plasma and produce plasma gas containing active species; a plasma functional liquid generation tank that stores the solvent and immerses the first electrode and the second electrode in it; and a plasma functional liquid generation unit that generates the plasma functional liquid by introducing the plasma gas in a bubbly state that has passed through the second electrode into the solvent. This configuration was adopted. [Effects of the Invention]

[0008] This invention allows plants to grow efficiently and at low cost because a plasma functional liquid containing active species with cleaning and disinfecting effects is directly supplied to the soil of plants, and the active species contained in the plasma functional liquid are absorbed by the plants in a short time. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of a spray hydroponic cultivation plant according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram showing the configuration of a spray hydroponic cultivation plant according to a second embodiment of the present invention. [Figure 3] This is a schematic diagram showing the configuration of a plasma functional fluid manufacturing apparatus according to a modified example. [Figure 4] This is a longitudinal cross-sectional view showing the main part of a modified plasma functional fluid manufacturing apparatus. [Figure 5] This is a schematic diagram showing the experimental procedure for Experimental Example 1. [Figure 6] This graph shows the experimental results for Experiment Example 1. [Figure 7] This is a schematic diagram showing the experimental procedure for Experiment Example 2. [Figure 8] This graph shows the experimental results for Experiment Example 2. [Figure 9] This graph shows the experimental results for Experiment Example 3. [Modes for carrying out the invention]

[0010] Each embodiment of the present invention will be described based on the drawings. In the following, when referring to the number of components, numerical values, amounts, ranges, etc., unless otherwise specified or clearly limited to a specific number in principle, it is not limited to that specific number, and it may be more or less than the specific number.

[0011] In addition, when referring to the shape, positional relationship, etc. of components, etc., unless otherwise specified or clearly considered not to be so in principle, it includes those substantially approximating or similar to the shape, etc.

[0012] In addition, the drawings may be exaggerated, such as enlarging characteristic parts for easy understanding of the characteristics, and the dimensional ratios of components, etc. are not necessarily the same as the actual ones. Also, in sectional views, in order to make the sectional structure of components easy to understand, the hatching of some components may be omitted.

[0013] <First Embodiment> First, the spray hydroponic cultivation plant 1A according to the first embodiment of the present invention will be described based on the drawings. FIG. 1 is a schematic diagram showing the configuration of the spray hydroponic cultivation plant 1A. The spray hydroponic cultivation plant 1A includes a cultivation tank 2 for spray hydroponic cultivation of a plant P and a plasma functional liquid manufacturing device 10.

[0014] The cultivation tank 2 includes a container 2a and a support portion 2b that supports the plant P and forms a space in the container 2a where the above-ground part of the plant P grows. Medium 部が成長する空間を形成する支持部2bと、を備えている。

[0015] The plasma functional liquid manufacturing device 10 includes a plasma head 20 that is a plasma gas generation part. The plasma head 20 may have any configuration as long as it generates plasma, but an atmospheric pressure plasma device that generates plasma at a pressure near atmospheric pressure is preferable. The atmospheric pressure plasma device is smaller in size, has excellent operability, and high safety compared to low-pressure plasma devices such as vacuum plasma devices. Furthermore, the atmospheric pressure plasma device can generate a higher concentration of active species compared to low-pressure plasma devices.

[0016] Inside the plasma head 20, plate-shaped first electrode 21 and second electrode 22 are provided, facing each other with a gap therebetween. The first electrode 21 is applied with a high-frequency voltage by a power supply 23. Also, the second electrode 22 is connected to the ground 24.

[0017] In the space between the first electrode 21 and the second electrode 22, a plasma generation gas is sent through a compressor 25. The plasma generation gas is a gas that generates plasma and contains at least one of air, carbon dioxide gas, oxygen gas, and nitrogen gas. When the oxygen concentration of the plasma generation gas is 90% or more, preferably 90% or more and 95% or less, excellent cleaning and sterilization effects are exhibited. The plasma generation gas may be adjusted in oxygen concentration in advance by an oxygen concentrator (not shown) as necessary. When the oxygen concentration of the plasma generation gas is less than 100%, the plasma generation gas contains a nitrogen component or the like. In particular, when a plasma generation gas with an oxygen concentration of 95% is generated using an oxygen concentrator that uses the PSA method of adsorbing nitrogen in the air to zeolite to generate high-concentration oxygen, theoretically about 0.5% of nitrogen is contained.

[0018] The plasma head 20 is connected to the plasma gas discharge part 30 through a gas conveyance path 31. Since the plasma head 20 and the plasma gas discharge part 30 are separated from each other, heat generated in the plasma head 20 is suppressed from being transmitted to the plasma gas discharge part 30.

[0019] One end of the gas conveyance path 31 is connected to the plasma head 20, and the other end is connected to the plasma gas discharge part 30, and the plasma gas generated in the plasma head 20 is sent to the plasma gas discharge part 30. The plasma gas is pressurized to such an extent that backflow from the plasma gas discharge part 30 to the plasma head 20 is suppressed.

[0020] The plasma gas emission unit 30 is immersed in a solvent S stored in a plasma functional liquid generation tank 41, which will be described later. The plasma gas emission unit 30 is a porous member formed, for example, in a hollow, substantially cylindrical shape, with numerous holes 32 formed on its outer surface. The plasma gas emission unit 30 introduces plasma gas bubbles B into the solvent S in the plasma functional liquid generation tank 41 by passing the plasma gas supplied to its interior through the holes 32.

[0021] The pore size of the holes 32 can be changed to any size corresponding to the initial bubble size of the bubbles B introduced into the solvent S in the plasma functional liquid generation tank 41. For example, depending on the pore size of the holes 32, it is possible to generate microbubbles with a bubble diameter of about 1 μm to 100 μm, or ultrafine bubbles with a bubble diameter of about several tens of nanometers to 1 μm.

[0022] Bubble B contains active species such as ozone, hydrogen peroxide, hydroxide radicals, nitrogen oxides, and singlet oxygen, depending on the type of plasma generating gas. In this specification, "active species" refers to radicals etc. that are generated when the plasma generating gas is activated by the plasma. The radicals contained in the plasma gas differ depending on the type of plasma generating gas used to generate the plasma gas. For example, if the plasma generating gas contains an oxygen component, oxygen radicals are generated, and if the plasma generating gas contains a nitrogen component, nitrogen oxide radicals are generated. Nitrate nitrogen (nitrate radicals) is also useful for plant growth.

[0023] The plasma gas emission section 30 is made of, for example, metal, ceramics, or plastic, preferably copper, silver, or an alloy thereof. This introduces copper ions or silver ions into the solvent S, thereby enhancing the cleaning and sterilizing effects of the plasma functional liquid L.

[0024] The plasma functional liquid manufacturing apparatus 10 includes a plasma functional liquid generation unit 40 that generates plasma functional liquid L. In this specification, "plasma functional liquid L" refers to a solution in which active species held in plasma gas are held in bubbles B in solvent S and then gradually dissolved in solvent S. That is, plasma functional liquid L contains active species held in bubbles B or active species dissolved in solvent S. By dissolving the active species in solvent S, solvent S itself is cleaned and disinfected, and plasma functional liquid L also cleans and disinfects other objects.

[0025] The plasma functional liquid generation unit 40 includes a plasma functional liquid generation tank 41 that stores solvent S and immerses the plasma gas emission unit 30 in the solvent S. Compared to conventional swirling flow methods, the plasma functional liquid generation tank 41 does not have stirring blades or the like to agitate the solvent S, and the generation of airflow in the solvent S is suppressed. The solvent S is water such as ultrapure water, ion-exchanged water, purified water, or distilled water, or a solution containing inorganic nutrients, or liquid fertilizer, but is not limited to these. When liquid fertilizer is used as the solvent S, the plasma functional liquid L can kill fungi contained in the liquid fertilizer, and active species suitable for the growth of plants P can be included in the liquid fertilizer. Furthermore, since the plasma head 20 is located outside the plasma functional liquid generation tank 41 and plasma gas is introduced into the solvent S from the plasma gas emission unit 30 immersed in the solvent S, compared to conventional venturi methods, the loss of activity of active species contained in the plasma functional liquid L due to the heat generated when generating plasma gas can be suppressed, and the lifespan of the active species can be extended.

[0026] The bubbles B are preferably microbubbles or ultrafine bubbles that are retained in the solvent S for a long time. In particular, when bubbles B are ultrafine bubbles, there is almost no buoyancy acting on them, so the bubble state is maintained for a long time.

[0027] The plasma functional liquid generation unit 40 includes a liquid supply passage 42 as a liquid supply unit and a spray head 43 as a liquid injection unit.

[0028] The liquid supply channel 42 delivers the plasma functional liquid L to the container 2a. The upstream end of the liquid supply channel 42 is connected to the plasma functional liquid generation tank 41, and it branches into three branches along the way, with each branch connected to one of the three spray heads 43. The plasma functional liquid L delivered through the liquid supply channel 42 is pressurized and pumped to the spray heads 43 using a pump or the like (not shown).

[0029] Three spray heads 43 are positioned at the bottom of the container 2a and spray the plasma functional liquid L towards the underground parts of the plants P. The number of spray heads 43 can be increased or decreased depending on the number of plants P and the area to which the spray heads 43 spray the plasma functional liquid L. The roots and other parts of the plants P that are sprayed with the plasma functional liquid L are disinfected or sterilized by the active species contained in the plasma functional liquid L.

[0030] The average particle size of the plasma functional liquid L sprayed from the spray head 43 is preferably 30 μm or less. As a result, the plasma functional liquid L sprayed from the spray head 43 floats in the container 2a for a predetermined time, and active species that did not reach the underground part of the plant P also float in the atmosphere of the plasma functional liquid L.

[0031] The spray head 43 is operated by a controller (not shown). The controller controls the timing and amount of plasma functional liquid L sprayed by the spray head 43 according to the temperature and the growth status of the plant P, which are obtained by sensors (not shown). If the spraying of plasma functional liquid L from the spray head 43 is stopped, the underground part of the plant P is exposed to the air, and the plant P can absorb sufficient oxygen.

[0032] In this way, the spray hydroponic cultivation plant 1A according to this embodiment has a cultivation tank 2 in which the plant P is grown hydroponically, with the support part 2b supporting the plant P with the underground part of the plant P exposed in the container 2a, and the underground part of the plant P Medium The device comprises a spray head 43 for injecting liquid into the unit and a liquid supply passage 42 for supplying liquid to the spray head 43, wherein the liquid is a plasma functional liquid L containing active species.

[0033] With this configuration, the plasma functional liquid L, which contains active species with cleaning and disinfecting effects, is directly supplied to the soil portion of the plant P. As a result, the active species contained in the plasma functional liquid L are absorbed by the plant P in a short time, allowing the plant P to grow efficiently and at low cost.

[0034] Furthermore, the spray hydroponic cultivation plant 1A according to this embodiment is configured such that the oxygen concentration of the plasma generation gas is 90% or higher.

[0035] With this configuration, a plasma gas containing highly effective active species with excellent cleaning and disinfecting properties is generated from a plasma generation gas with an oxygen concentration of 90% or higher, thereby obtaining a plasma functional liquid L with excellent cleaning and disinfecting properties that contains long-lived active species.

[0036] Furthermore, the spray hydroponic cultivation plant 1A according to this embodiment is configured such that the oxygen concentration of the plasma generation gas is 90% or more and 95% or less.

[0037] This configuration allows for the easy acquisition of plasma generating gas using a small oxygen concentrator, and suppresses the generation of ozone that occurs when the oxygen concentration is excessively high, thus enabling the production of a plasma functional liquid L that is highly efficient and economical.

[0038] Furthermore, the spray hydroponic cultivation plant 1A according to this embodiment is configured such that the nitrogen concentration of the plasma generation gas is 0.5% or higher.

[0039] With this configuration, nitrate ions derived from nitrogen gas contained in the plasma generation gas dissolve in the plasma functional liquid L, making it possible to obtain a plasma functional liquid L suitable for plant growth.

[0040] Furthermore, the spray hydroponic cultivation plant 1A according to this embodiment is configured such that the average diameter of the bubble-like plasma gas at the initial stage of generation is 1 μm or more and less than 100 μm.

[0041] With this configuration, microbubbles or ultrafine bubbles B are retained for a long period of time, thus enabling the active species contained in the plasma functional liquid L to be maintained for an extended period.

[0042] Furthermore, the spray hydroponic cultivation plant 1A according to this embodiment is configured such that the average particle size of the plasma functional liquid L sprayed by the spray head 43 immediately after spraying is 30 μm or less.

[0043] With this configuration, the plasma functional liquid L sprayed from the spray head 43 floats in the container 2a for a predetermined time, and the active species that did not reach the soil of the plant P also float in the atmosphere of the plasma functional liquid L, making them easily absorbed by the soil of the plant P and allowing for efficient use of the active species.

[0044] <Second Embodiment> Next, a spray hydroponic cultivation plant 1B according to a second embodiment of the present invention will be described with reference to the drawings. Figure 2 is a schematic diagram showing the configuration of the spray hydroponic cultivation plant 1B according to the second embodiment. Note that the spray hydroponic cultivation plant 1B according to this embodiment differs from the spray hydroponic cultivation plant 1A according to the first embodiment described above in the following respects, while other configurations are common. Therefore, common components are denoted by the same reference numerals and redundant descriptions are omitted.

[0045] The plasma functional liquid generation unit 40 is equipped with a liquid circulation path 44 that connects the container 2a and the plasma functional liquid generation tank 41. The liquid circulation path 44 has its upstream end connected to the container 2a and its downstream end connected to the plasma functional liquid generation tank 41. The plasma functional liquid L that remains in the container 2a without being absorbed by the plant P is returned from the container 2a to the plasma functional liquid generation tank 41 via the liquid circulation path 44 by a pump or the like (not shown).

[0046] The plasma functional liquid L refluxed from container 2a is mixed with the solvent S stored in the plasma functional liquid generation tank 41, and plasma gas bubbles B released from the plasma gas emission unit 30 are introduced into the solvent S stored in the plasma functional liquid generation tank 41. In this way, the plasma functional liquid L containing dissolved active species circulates between the plasma functional liquid generation unit 40 and the cultivation tank 2.

[0047] Furthermore, since the lifespan of the liquid fertilizer contained in solvent S is longer than the lifespan of the active species, the liquid fertilizer can be reused repeatedly by continuously supplying the active species as described above.

[0048] <Variation> Next, a modified example of the plasma functional fluid manufacturing apparatus 10 will be described based on the drawings. Figure 3 is a schematic diagram showing the configuration of the plasma functional fluid manufacturing apparatus 50 according to this modified example. Figure 4 is a longitudinal cross-sectional view showing the main part of the plasma functional fluid manufacturing apparatus 50. Note that the plasma functional fluid manufacturing apparatus 50 according to this modified example differs from the plasma functional fluid manufacturing apparatus 10 described above in the following points, while other configurations are common. Therefore, common configurations are denoted by the same reference numerals, and redundant explanations are omitted.

[0049] The plasma functional liquid manufacturing apparatus 50 is equipped with a plasma head 60, which is a plasma gas generation unit. The plasma head 60 can have any configuration as long as it generates plasma, but an atmospheric pressure plasma device that generates plasma at a pressure near atmospheric pressure is preferred. Compared to low-pressure plasma devices such as vacuum plasma devices, atmospheric pressure plasma devices are smaller in size, easier to operate, and safer. Furthermore, atmospheric pressure plasma devices can generate higher concentrations of active species compared to low-pressure plasma devices.

[0050] The plasma head 60 comprises a cylindrical first electrode 61 and a hollow, substantially cylindrical second electrode 62 that houses the first electrode 61. The first electrode 61 and the second electrode 62 are arranged substantially coaxially. The first electrode 61 and the second electrode 62 are immersed in a solvent S stored in a plasma functional liquid generation tank 41.

[0051] The first electrode 61 is connected to a power supply 63 located outside the plasma functional liquid generation tank 41 via a power supply cable 63a. The second electrode 62 is connected to an earth 64 located outside the plasma functional liquid generation tank 41 via an earth wire 64a.

[0052] A dielectric layer 65, which is made of a dielectric material, is provided on the outer circumference of the first electrode 61. By interposing the dielectric layer 65 between the first electrode 61 and the second electrode 62, plasma can be generated stably.

[0053] Plasma generation gas is supplied to the space between the first electrode 61 and the second electrode 62 from a compressor 66 located outside the plasma functional liquid generation tank 41 via a gas supply passage 66a. The downstream end of the gas supply passage 66a extends through a support member 68 into the plasma head 60. The plasma generation gas contains at least one of the following: air, carbon dioxide, oxygen, and nitrogen. The oxygen concentration of the plasma generation gas is set to 90% or higher, preferably 90% to 95%. If the oxygen concentration of the plasma generation gas is less than 100%, the plasma generation gas contains nitrogen components, etc. The nitrogen component of the plasma generation gas is preferably 5% or less. When a high-frequency voltage is applied between the first electrode 61 and the second electrode 62, plasma is generated from the plasma generation gas.

[0054] Disc-shaped support members 67 and 68 are positioned at both ends of the second electrode 62. Support member 67 is provided on the tip side of the second electrode 62. Support member 68 is provided on the base end side of the second electrode 62 and supports the first electrode 61, the dielectric layer 65, and the gas supply path 66a. Reference numeral 69 in Figures 3 and 4 indicates a protective tube that protects the power supply cable 63a, the ground wire 64a, etc.

[0055] The second electrode 62 also serves as a plasma gas emission section. That is, the second electrode 62 is a porous metal member with numerous holes 32 formed on its outer surface. Preferably, the second electrode 62 is made of copper, silver, or an alloy thereof. This allows copper ions or silver ions to be introduced into the solvent S. The second electrode 62 introduces plasma gas bubbles B into the solvent S in the plasma functional liquid generation tank 41 by passing the plasma gas supplied inside through the holes 32.

[0056] By connecting the conductive second electrode 62 to the earth 64, the device can be simplified and miniaturized, and made portable. Furthermore, the metallic second electrode 62 has high thermal conductivity, allowing it to efficiently dissipate the heat generated by the plasma into the solvent S, thereby suppressing the thermal effects on the active species. In addition, since plasma is generated across the entire second electrode 62, the plasma gas can be generated almost uniformly without bias within the plasma head 60, allowing the bubbles B to easily diffuse into the solvent S. [Examples]

[0057] (Experimental Example 1) A comparative experiment was conducted to examine the sterilization effects of the plasma gases generated when oxygen, carbon dioxide, air, and nitrogen were used as the plasma generation gases.

[0058] First, 248 ml of purified water and 2 ml of spore solution were mixed to prepare a 250 ml spore suspension. The spores used in the spore solution were Fusarium oxysporum f.sp. fragariae: NBRC 31982. These spores are the main cause of strawberry wilt disease, and by disinfecting or sterilizing them, it is possible to control the disease in strawberries and suppress growth inhibition and wilting.

[0059] Next, as shown in Figure 5, 50 ml of spore suspension was placed in beaker 101 and plasma treatment was performed using plasma gas in the plasma bubbling apparatus 100. The plasma gas generated by the multi-gas plasma jet 102, which is the plasma generation unit, was sent via cylindrical piping 103 to the porous filter 104, which is the plasma gas emission unit immersed in the spore suspension, and introduced into the spore suspension in the form of bubbles through the porous filter 104. The length of cylindrical piping 103 was set to approximately 90 mm, the length of porous filter 104 to approximately 20 mm, and the flow rate of the introduced plasma gas was set to 3 SLPM.

[0060] Four types of plasma generating gases were prepared to generate plasma gas: oxygen, carbon dioxide, air, and nitrogen. The time for introducing the plasma gas generated from each gas into the spore suspension in bubble form (processing time) was set to 0 seconds, 120 seconds, 300 seconds, and 600 seconds.

[0061] Then, 1 ml of the spore suspension, into which a plasma gas in a bubbly state had been introduced, was serially diluted and then dropped onto an agar medium in a Petri dish 105. After incubation at room temperature for 2 days, the number of spores that germinated was counted. The results are shown in Figure 6.

[0062] As shown in Figure 6, when oxygen gas is used as the plasma generating gas, a bubbling period of 120 seconds is required for the plasma gas; when carbon dioxide gas is used as the plasma generating gas, a bubbling period of 300 seconds or more is required for the plasma gas; and when air is used as the plasma generating gas, a bubbling period of 600 seconds or more is required for the plasma gas to be generated. On the other hand, the bubbling effect of plasma gas generated using nitrogen gas is smaller than that of plasma gas generated from oxygen, carbon dioxide, or air. From these results, it can be concluded that using oxygen gas as the plasma generating gas is the most effective.

[0063] (Experimental Example 2) Next, we conducted an experiment to verify the relationship between the oxygen concentration of the oxygen gas contained in the plasma generation gas and the sterilization effect of the plasma gas.

[0064] As shown in Figure 7, 50 ml of purified water was placed in beaker 101, and plasma gas was introduced into the purified water using a plasma bubbling device 100. Specifically, the plasma gas generated by the multi-gas plasma jet 102, which is the plasma generation unit, was sent via cylindrical piping 103 to a porous filter 104, which is the plasma gas discharge unit immersed in purified water, and introduced into the purified water in the form of bubbles through the porous filter 104. The length of the cylindrical piping 103 was set to approximately 90 mm, the length of the porous filter 104 to approximately 20 mm, and the flow rate of the introduced plasma gas was set to 3 SLPM.

[0065] Five types of plasma generating gases were prepared, and the time for introducing the plasma gas generated from each gas into the spore suspension in a bubble state (processing time) was set to 60 seconds and 300 seconds. Plasma generation gas 1: 100% air (21% oxygen, 78% nitrogen, 1% argon) Plasma generation gas 2: 40% oxygen, 58% nitrogen, 2% argon Plasma generation gas 3: 70% oxygen, 27% nitrogen, 3% argon Plasma generation gas 4: 90% oxygen, 6% nitrogen, 4% argon Plasma generating gas 5: 100% oxygen

[0066] Next, 10 μl of spore lysate was mixed with 990 μl of purified water into which a plasma gas in a bubbly state had been introduced, and the mixture was allowed to stand for 10 minutes to prepare a spore suspension. The spores used in the spore lysate were Fusarium oxysporum f.sp. fragariae: NBRC 31982. Then, 1 ml of the spore suspension was serially diluted and dropped onto agar plates in a Petri dish 105, and incubated at room temperature for 2 days before the number of viable bacteria was counted. The results are shown in Figure 8.

[0067] As shown in Figure 8, when the oxygen concentration of the plasma generating gas was set to 90% and 100%, the number of surviving bacteria decreased significantly at bubbling times (processing times) of 60 seconds and 300 seconds, indicating a remarkable sterilization effect. On the other hand, when the oxygen concentration of the plasma generating gas was set to 21%, 40%, and 70%, the decrease in the number of surviving bacteria, i.e., the sterilization effect, was smaller compared to the 90% and 100% oxygen concentrations.

[0068] (Experimental Example 3) Next, we conducted an experiment to further investigate the relationship between the oxygen concentration of the oxygen gas contained in the plasma generation gas and the sterilization effect of the plasma gas.

[0069] In the same manner as in Experimental Example 2, a spore suspension was prepared by mixing 990 μl of purified water with 10 μl of spore saturate. The spores in the spore saturate were Fusarium oxysporum f.sp. fragariae: NBRC 31982, as in Experimental Example 2.

[0070] Three types of plasma generating gases were prepared, and the time for introducing the plasma gas generated from each gas into the spore suspension in bubble form (processing time) was set to 10 seconds, 20 seconds, 30 seconds, and 60 seconds. The results are shown in Figure 9. Plasma generation gas 6: 80% oxygen, 17% nitrogen, 3% argon Plasma generation gas 7: 90% oxygen, 6% nitrogen, 4% argon Plasma generating gas 8: 100% oxygen

[0071] Figure 9 shows that when the oxygen concentration of the plasma generating gas is set to 90% and 100%, the number of surviving bacteria decreases significantly after a bubbling time (processing time) of 10 seconds or more, resulting in a remarkable sterilization effect. On the other hand, when the oxygen concentration of the plasma generating gas is set to 80%, the reduction in the number of surviving bacteria, i.e., the sterilization effect, is smaller compared to when the oxygen concentration is 90% and 100%.

[0072] Note that although the plasma generating gas 4 in Experimental Example 2 and the plasma generating gas 7 in Experimental Example 3 were conducted using the same components, the number of spores per unit volume of the spore solution used in the experiment differed from experiment to experiment, and the number of viable bacteria before culturing in the petri dish differed. Therefore, the absolute values ​​of the number of viable bacteria in Figures 8 and 9 are different. The same applies to plasma generating gas 5 in Experimental Example 2 and plasma generating gas 8 in Experimental Example 3.

[0073] Thus, oxygen gas is very effective as a plasma generating gas, and in particular, a remarkable sterilization effect can be obtained when the oxygen concentration is at least 90% or higher. However, if the oxygen concentration is higher than 95%, a very expensive high-concentration oxygen generator is required, making it impractical. On the other hand, if the oxygen concentration is set to 95% or lower, a small oxygen concentrator can be used. Furthermore, if the oxygen concentration is excessively high, the amount of ozone generated increases, raising concerns about its effects on humans and plants. In particular, if the oxygen concentration is higher than 95%, the ozone introduced into the liquid does not dissolve in the liquid and is released into the air, requiring separate ozone countermeasures. Therefore, considering workability and cost, an oxygen concentration of 90% to 95% is preferable.

[0074] When the oxygen concentration is below 95%, the plasma generation gas also contains nitrogen gas. As a result, nitrate ions, which function as nutrients for plant growth, are generated as active species in the plasma functional liquid L.

[0075] Furthermore, the present invention can be modified in various ways other than those described above, as long as it does not deviate from the spirit of the invention, and it goes without saying that the present invention extends to such modified forms. [Explanation of symbols]

[0076] 1A, 1B: Spray hydroponics plant 2:Cultivation tank 2a: Container 2b: Support part 10, 50: Plasma functional liquid manufacturing equipment 20, 60: Plasma head 21, 61: First electrode 22, 62: Second electrode 23, 63: Power supply 24, 64: Earth 25, 66: Compressor 30: Plasma gas emission section 31: Gas transport route 32: Hole 40: Plasma functional liquid generation unit 41: Plasma functional liquid generation tank 42:Liquid supply path 43: Spray head 44:Liquid circulation path 63a: Power supply cable 64a: Ground wire 65: Dielectric layer 66a: Gas supply line 67, 68: Support members 69: Protection tube B: Air bubbles L: Plasma functional liquid P:Plant S: Solvent

Claims

1. A cultivation tank for hydroponically growing plants, in which the plant's underground portion is exposed within the container and the support part supports the plant, A liquid injection unit that sprays a plasma functional liquid containing active species into the soil of the aforementioned plant, A liquid supply unit that supplies the plasma functional liquid to the liquid injection unit, A plasma functional liquid manufacturing apparatus that produces the plasma functional liquid by introducing plasma gas generated from plasma generation gas into a solvent, Equipped with, The plasma functional liquid manufacturing apparatus is A plasma gas generation unit comprising a first electrode to which a high-frequency voltage is applied, a second electrode made of a porous metal material positioned opposite the first electrode across a space and connected to earth, and a gas supply path for supplying plasma generating gas to the space, wherein a high-frequency voltage is applied between the first electrode and the second electrode to generate plasma in the plasma generating gas in the space and generate plasma gas containing active species, The system includes a plasma functional liquid generation tank for storing the solvent and immersing the first electrode and the second electrode, and a plasma functional liquid generation unit for generating the plasma functional liquid by introducing the plasma gas in a bubbly state that has passed through the second electrode into the solvent. A spray hydroponic cultivation plant characterized by having the following features.

2. The spray hydroponic cultivation plant according to claim 1, characterized in that the plasma functional liquid production apparatus includes a plasma functional liquid recovery unit that recovers the plasma functional liquid sprayed by the liquid injection unit and recirculates it from the cultivation tank to the plasma functional liquid production apparatus.

3. The spray hydroponic plant according to claim 1 or 2, characterized in that the solvent includes water or liquid fertilizer.

4. The spray hydroponic cultivation plant according to any one of claims 1 to 3, characterized in that the plasma generating gas includes at least one of air, carbon dioxide gas, oxygen gas, and nitrogen gas.

5. The plasma generating gas includes oxygen gas, The spray hydroponic cultivation plant according to any one of claims 1 to 3, characterized in that the oxygen concentration of the plasma generating gas is 90% or more.

6. The plasma generating gas includes oxygen gas, The spray hydroponic cultivation plant according to claim 5, characterized in that the oxygen concentration of the plasma generating gas is 90% or more and 95% or less.

7. The spray hydroponic cultivation plant according to claim 5 or 6, characterized in that the nitrogen concentration of the plasma generation gas is 0.5% or more.

8. The spray hydroponic cultivation plant according to any one of claims 1 to 7, characterized in that the plasma functional liquid is generated by atmospheric pressure plasma discharge.

Images