NZ521709A

NZ521709A - Plant growing method and apparatus

Info

Publication number: NZ521709A
Application number: NZ521709A
Authority: NZ
Inventors: Akihisa Minato; Takayuki Asada
Original assignee: Oji Paper Co
Priority date: 2001-10-02
Filing date: 2002-10-01
Publication date: 2003-08-29
Also published as: JP2003111521A; ZA200402799B; AU2002301265B2; CN1265698C; CN1498073A; BR0206090A; WO2003030628A1

Abstract

A plant growing method comprising a step of supplying CO2, O2 or N2 in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to an opposite side of the permeable membrane, a step of dissolving the CO2 , O2 or the N2 in the raw water so as to reach a predetermined concentration, and a step of intermittently atomizing resultant CO2, O2 or N2 dissolved water onto plants thereby promoting plant growth.

Description

<div class="application article clearfix" id="description"> 52 170 S NEW ZEALAND PATENTS ACT, 1953 No: Date: COMPLETE SPECIFICATION PLANT GROWING METHOD AND APPARATUS We, OJI PAPER CO., LTD., a Japanese Company of 4-7-5, Ginza, Chuoku, Tokyo, Japan, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 1 - (followed by page la) INTELLECTUAL PROPERTY OFFICE OF N.Z - 1 OCT 2002 RECEIVED Plant growing method and apparatus BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a plant growing method and an apparatus for a plant growing apparatus. More specifically, this invention relates to a plant growing method according to which, for example, the yield of plants is raised by supplying water, in which various gases are dissolved, to the plants, and relates to a plant growing apparatus for producing the gas-dissolved water. 2. Description of the Prior- Art A technique for raising the yield of a plant by spraying water in which a C02 gas is dissolved (hereinafter, referred to as "C02-dissolved water" ) onto the leaf surface of the plant so as to activate photosynthesis of the plant has been variously proposed as a plant-growing method that uses water suitable for plant growth. For instance, a first example is a method in which a substance, such as dry ice or ammonium carbonate, which generates C02 when it comes in contact with water, is brought into contact with water. A second example is a method in which a C02 gas obtained by burning fossil fuels or a C02 gas with which a gas cylinder is filled is introduced into a water tank, thereby generating bubbles. A third example is a method in which a C02 gas that is generated by subjecting water to electrolysis with a carbonaceous electrode is dissolved. (Japanese Unexamined Patent Publication No. H6-154760, Japanese Unexamined Patent Publication No. H8-84530, etc.) However, in the conventional techniques mentioned above, the dissolution efficiency of C02 to water is small, and C02-dissolved water is produced under normal pressure (1 atmospheric pressure). Therefore, C02 concentration has its limits. Additionally, in the conventional techniques, what is disclosed as water suitable for plant growth is only the C02-dissolved water. SUMMARY OF THE INVENTION The present invention has been made in consideration of these circumstances, and it is an ob j ect of the present invention to provide an apparatus for producing only a necessary amount of various gas-dissolved water suitable for plant growth that has a higher concentration than a conventional apparatus and supplying it to plants, and to provide a plant growing method that uses the highly concentrated gas-dissolved water produced 2 by this apparatus. A plant growing method of the present invention is characterized by a step of supplying C02 or 02 or N2 in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to the other side of the permeable membrane, a step of dissolving the C02 or 02 or N2 in the raw water so as to reach a predetermined concentration of water, and a step of intermittently atomizing resultant C02- or 02-or N2-dissolved water onto plants, thereby promoting plant growth. The permeable membrane that is permeable only to a gas and impermeable to a liquid is a non-porous gas permeable membrane. The non-porous gas permeable membrane is a membrane through which a gas can pass according to a dissolution/diffusion mechanism, and the permeable membrane does not substantially have pores through which molecules can pass like a Knudsen flow in the state of a gas. As a result of use of the thus structured non-porous gas permeable membrane, it becomes possible to supply and dissolve a gas under arbitrary pressure without allowing the gas to be discharged in the form of bubbles. Additionally, it becomes possible to dissolve it efficiently, with good controllability, and easily so as to reach an arbitrary concentration. 3 A flat membrane, a tubular membrane, a hollow fiber membrane, a spiral membrane, etc., can be mentioned as the membranal form of the permeable membrane, and the hollow fiber membrane is preferred because its membranal surface area is large. Additionally, the hollow fiber membrane is preferred because an apparatus can be made compact and can be easily operated. The hollow fiber membrane is not limited to a specific arrangement. However, it is preferable to have an arrangement in which spaces between the hollow fiber membranes are maintained at even intervals like bamboo-blind weaving because the danger of the occurrence of channeling is slight when raw water or a gas is caused to flow. The non-porous hollow fiber membrane is not limited to a specific structure. However, in order to improve the gas permeability of the non-porous membrane, it is preferable to have a composite-membrane structure in which a thin non-porous layer is supported and fixed by a porous layer. Likewise, the composite-membrane structure is not limited to a specific one. However, it is preferable to have a three-layer composite hollow fiber membrane sandwiched by porous layers from both sides of the thin non-porous layer excellent in gas permeability because the thin layer is protected. Since a permeable membrane (preferably, a hollow fiber 4 membrane) that is permeable only to a gas and impermeable to a liquid is used in the present invention as described above, a high concentration of C02- or 02- or N2-dissolved water can be supplied to plants immediately without requiring setup time in spite of intermittent running. That is, only a necessary amount of gas-dissolved water can be produced and be supplied to plants. The concentration of the C02-dissolvedwater is preferably 1000 ppm or more, more preferably 2000 ppm, and even more preferably a saturated concentration. The concentration of the 02-dissolved water is preferably 30 ppm or more, more preferably 60 ppm, and even more preferably a saturated concentration. The concentration of the N2-dissolved water is preferably 15 ppm or more, more preferably 30 ppm, and even more preferably a saturated concentration. Preferably, the atomizing time of the C02- or 02- or N2-dissolved water at a time is set to be sufficient for water adhering to a plant surface to begin to drop, and the atomizing interval of the C02- or 02- or N2-dissolved water is set to be sufficient for the water adhering to the plant surface to be dried. When gas-dissolved water is atomized in the present invention, C02-dissolved water (or 02-dissolved water or 5 N2-dissolved water) that substantially contains only C02 (or only 02 or only N2) is preferred, and it is preferable to allow the plant to absorb necessary nourishment from its roots without especially containing nutrient salts. In a condition that includes no nutrient salts, even if a leaf surface is dried because of intermittent running, there is no fear that the leaf will rot resulting from the fact that the concentration of the nutrient salts becomes high, and it is possible to supply an optimum amount of C02 or 02 or N2 without considering the relationship (percentage) with other components. Additionally, a plant growing method of the present invention is characterized by a step of supplying C02 or 02 or N2 in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to the other side of the permeable membrane, a step of dissolving the C02 or 02 or N2 in the raw water so as to reach a predetermined concentration of water, and a step of intermittently irrigating resultant C02- or 02- or N2-dissolved water onto plants , thereby promoting plant growth. It is preferable to intermittently supply the gas-dissolved water also in this invention. Referring to the preferred concentration of the gas-dissolved water, the concentration of the C02-dissolved water is preferably 1000 6 ppm or more, more preferably 2000 ppm, and even more preferably a saturated concentration. The concentration of the 02-dissolved water is preferably 30 ppm or more, more preferably 60 ppm, and even more preferably a saturated concentration. The concentration of the N2-dissolved water is preferably 15 ppm or more, more preferably 30 ppm, and even more preferably a saturated concentration. Since a permeable membrane module, such as a hollow fiber membrane module, is used, the saturated concentration can be easily realized. The present invention is also a plant growing apparatus by which C02- or 02- or N2-dissolved water is intermittently atomized onto plants, thereby promoting plant growth. This plant growing apparatus includes a permeable membrane module in which C02 or 02 or N2 is supplied in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to the other side of the permeable membrane, and the C02 or 02 or N2 is dissolved in the raw water so as to reach a predetermined concentration of water. The present invention is also a plant growing apparatus by which C02- or 02- or N2-dissolved water is intermittently irrigated onto plants, thereby promoting plant growth. This plant growing apparatus includes a permeable membrane module in which C02 or 02 or N2 7 is supplied in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to the other side of the permeable membrane, and the C02 or 02 or N2 is dissolved in the raw water so as to reach a predetermined concentration of water. Also in this invention, since a permeable membrane module, such as a hollow fiber membrane module, is used, a preferred concentration of gas-dissolved water can be swiftly produced. Referring to the preferred concentration of the gas-dissolved water, the concentration of the C02-dissolved water is preferably 1000 ppm or more, more preferably 2000 ppm, and even more preferably a saturated concentration. The concentration of the 02-dissolved water is preferably 30 ppm or more, more preferably 60 ppm, and even more preferably a saturated concentration. The concentration of the N2-dissolved water is preferably 15 ppm or more, more preferably 30 ppm, and even more preferably a saturated concentration. The present invention is also a plant growing apparatus that selectively performs either the step of intermittently atomizing C02- or 02- or N2-dissolved water onto plants or the step of intermittently irrigating C02- or 02- or N2-dissolved water onto plants, thereby promoting plant growth. This plant 8 growing apparatus includes a permeable membrane module in which C02 or 02 or N2 is selectively supplied in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to the other side of the permeable membrane, and the C02 or 02 or N2 is dissolved in the raw water so as to reach a predetermined concentration of water. Preferably, in these plant growing apparatuses, a second flow path separated from a first flow path leading to plants is provided on the downstream side of the permeable membrane module, and a switching valve for automatically opening the second flow path when pressure in the first flow path exceeds a predetermined value is provided, from the viewpoint of safety. Preferably, pressure gauges are provided on the upstream side and on the downstream side, respectively, of the permeable membrane module, and an indicating means for indicating a difference between the pressure gauges when the difference exceeds a predetermined value is provided. In this case, the directions of the permeable membrane module on the upstream and downstream sides can be changed, or the time when the permeable membrane module should be replaced with another can be known. 9 DESCRIPTION OF THE DRAWINGS The foregoing and other features and advantages of the present invention will become more readily more appreciated as the same becomes better understood by reference to the following detailed description when taken into conjunction with the accompanying drawings wherein: Fig. 1 is a view showing a plant growing apparatus, which is a first embodiment of the present invention, and a method of supplying C02-dissolved water produced by this apparatus. Fig. 2 shows a hollow fiber membrane module. Fig. 3 is a view showing a plant growing apparatus, which is a second embodiment of the present invention, and a method of supplying 02-dissolved water produced by this apparatus. Fig. 4 is a view showing a plant growing apparatus, which is a third embodiment of the present invention, and a method of supplying C02-dissolved water and 02-dissolved water produced by this apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the attached drawings, a description will hereinafter be given of a plant growing apparatus of the present invention (hereinafter, abbreviated as "present apparatus") and a plant growing method that uses a high 10 concentration of gas-dissolved water produced by the present apparatus. Fig. 1 is a view showing an example of the present apparatus and an example of a method for supplying C02-dissolved water produced by the present apparatus. The present apparatus is roughly made up of, from the upstream side, a raw water tank WT, a pressure pump P, a filter F, a hollow fiber membrane module MO, a first pressure gauge PI and a second pressure gauge P2 that are disposed at an entrance part and an exit part, respectively, of the hollow fiber membrane module MO, a C02 gas cylinder 1, a control valve SV2, and a relief valve S. Operations of the entire apparatus are controlled by a control unit not shown. The raw water tank WT is a container for holding raw water used to produce C02-dissolved water by means of the present apparatus. The kind of raw water used for the present apparatus is not limited to a specific one, but, in consideration of costs, it is preferable to use tap water. More preferably, functional water, such as electrolytic ionic water or magnetic water, for aiding plant growth is used because the group of molecules of functional water is smaller in size than that of ordinary tap water, so that plants can easily absorb gas-dissolved water. The pressure pump P is used to supply raw water, such 11 as tap water, to the hollow fiber membrane module MO. The flow rate and the flow velocity of the raw water depend on the discharging ability of the pressure pump. In the present apparatus, it is preferable to supply a flow rate of 1 to 15 liters/minute. The filter F disposed on the downstream side of the pressure pump P is used if necessary, in order to remove fine particles included in the raw water discharged from the pressure pump P. Fine particles whose size is, for example, 25 pim or more can be removed by using this filter F. As a result, the hollow fiber membrane 3 that constitutes the hollow fiber membrane module MO disposed on the downstream side can be prevented from being contaminated. It is preferable to remove fine particles (microorganisms) whose size is 1 ^m to 10 (xm when necessary. The first and second pressure gauges PI and P2 disposed at the entrance and exit, respectively, of the hollow fiber membrane module MO is used to indicate the replacement time of the hollow fiber membrane module MO. When a pressure difference between the results measured by both of the pressure gauges exceeds a predetermined value, the information that the hollow fiber membrane module MO should be replaced is issued. Normally, the condition where the pressure difference therebetween exceeds the predetermined value can be handled 12 by replacing the upstream side with the downstream side. As shown in Fig. 1, a part of the output of the hollow fiber membrane module MO is returned to an input side JN of the pressure pump through the relief valve S. The relief valve S serves to prevent hydraulic pressure from abnormally rising even when the atomizing nozzle of a spreader 6 causes clogging, for example. However, if some process water is always returned, a high concentration of gas-dissolved water can be easily generated by circulation of the process water. The hollow fiber membrane module MO is used as an air supply membrane module for producing C02-dissolved water by supplying a C02 gas while causing the raw water from the upstream side to pass through. The hollow fiber membrane module MO is constructed such that tens of hundreds to tens of thousands of hollow fiber membranes 3 are bundled together and are included in a supporting case. The hollow fiber membrane module MO is characterized in that the lifetime is long under normal working conditions and in that maintenance is hardly needed. Preferably, the hollow fiber membrane 3 that constitutes the hollow fiber membrane module MO has a three-layer composite-membrane structure in which a non-porous membrane 4 is tightly inserted between porous membranes 5 and 5 like a sandwich so as to have a cylindrical shape as shown in Fig. 13 2(a). The non-porous membrane 4 is characterized by being impermeable to water and, on the other hand, selectively permeable to gases. Therefore, when a gas is pressurized from the outside of the hollow fiber membrane 3, the gas can be mixed with water inside the hollow fiber membrane 3. Therefore, in the present apparatus, C02-dissolved water is produced by supplying C02 while causing water to flow into the inside of the hollow fiber membrane 3 and pressurizing the C02 from the outside of the hollow fiber membrane 3 as shown in Fig. 2(b) . Instead, the C02-dissolved water may be produced by supplying C02 while causing water to flow to the outside of the hollow fiber membrane 3 and pressurizing the C02 from the inside of the hollow fiber membrane 3. In any case, in the present apparatus, the dissolution efficiency of C02 to the hollow fiber membrane 3 can be greatly raised by bring about a pressure gradient inside and outside the hollow fiber membrane 3, and C02-dissolved water in which C02 is dissolved in raw water to the extent of a saturated concentration can be easily produced. What is necessary for this is to set gas pressure to be about 0.5 to 2.0 kgf/cm2 higher than inside the hollow fiber membrane 3, by use of the control valve SV2 disposed between the hollow fiber membrane module MO and the C02 gas cylinder 1. Normal gas pressure is about 14 1.5 kgf/cm2, and, preferably, it is set at high pressure corresponding to the flow rate of the raw water. Since a small gas cylinder of, for example, about 1 to 30 Kg can be used as the C02 gas cylinder of the present apparatus, the entirety of the present apparatus can be made compact. The C02-dissolved water produced by being passed through the hollow f iber membrane module MO has a higher C02 concentration than that of C02-dissolved water produced according to the conventional technique. As an example, the solubility of C02 at 20°C under normal atmospheric pressure is about 1.78-g C02/1-liter H20. This C02 concentration is the upper limit obtained according to the conventional technique. In contrast, according to the present apparatus, C02 can be dissolved to a saturated concentration that corresponds to gas pressure by applying the gas pressure (1.4 to 5.0 kgf/cm2) onto the hollow fiber membrane module MO at 20°C. Therefore, according to the present apparatus, a high concentration of C02-dissolved water of 2.00-g C02/l-liter H20 can be obtained at a minimum. The same applies to other temperature regions excluding 20°C. 02-dissolved water or N2-dissolved water produced by being passed through the hollow fiber membrane module MO has a higher concentration of 02 or N2 than the concentration of a gas dissolved in water under normal atmospheric pressure. As an example. 15 the solubility of 02 at 20°C under normal atmospheric pressure is about 44.3-mg 02/l-liter H20. This 02 concentration is the upper limit under atmospheric pressure. In contrast, according to the present apparatus, 02 can be dissolved to a saturated concentration that corresponds to gas pressure as in the condition where C02 is dissolved. The same applies to the condition where N2 is dissolved. The exit part of the hollow fiber membrane module MO is connected to the spreader 6 through the second pressure gauge P2 described later. In a normal operation condition, C02-dissolved water that has passed through the exit part of the hollow fiber membrane module MO is sent to the spreader 6, and is sprayed onto plants through a spray member 61 of the spreader 6. The position of the spreader 6 with respect to the plants is not limited to a specific one. The spreader 6 may be situated above the plants and be directed downward for spraying as shown in Fig. 1, or, alternatively, the spreader 6 may be situated under the plants and be directed upward for spraying. The spraying form of gas-dissolved water is not limited to a specific one. However, generally, it is preferable to use an atomizing nozzle as the spray member 61 and spray the gas-dissolved water in a mist form. Accordingly, the 16 gas-dissolved water is uniformly sprayed onto the leaf surface of a plant, and is supplied to the interior of the plant through stomata, and, as a result, plant growth is promoted. The amount of gas-dissolved water to be spread at a time is not limited to a specific one. However, generally, atomizing time falls within 5 to 180 seconds, by which water adhering to the surface of the plant can sufficiently begin to drop. Preferably, it is 100 to 600 cc/min for one spray member. Thus, according to the present apparatus, since a high dissolution speed of a gas with respect to the hollow fiber membrane module MO is used, gas-dissolved water dissolved in raw water to the extent of a saturated concentration under the pressurized condition can be produced and supplied to plants in an extremely short time, by a necessary amount, and continuously. Herein, the operation that activates photosynthesis, which the aforementioned C02-dissolved water having a high concentration shows, can be considered as follows. First, C02 dissolved in water has its part changed into a carbonic acid (H2C03), and this undergoes ionization so as to generate a hydrogencarbonate ion (HC03") and a hydrogen ion (H+) . When a high concentration of C02-dissolved water obtained by the present apparatus is sprayed onto a plant, a higher concentration 17 gradient than that of the conventional technique occurs between the outer periphery and the interior of a plant leaf, thus raising the amount of C02 and the amount of hydrogencarbonate ion that are diffused and taken into the plant in a unit time. Thereafter, the hydrogencarbonate ion that has been taken into the plant undergoes a catalyst of carbonate dehydratase (carbonic anhydrase), which widely exists in plants, and is promptly transformed into C02. Thus, the C02 concentration in a chloroplast stroma rises, and the substrate concentration of ribulosebisphosphate carboxylase, which is a C02-fixing enzyme, rises. Therefore, photosynthesis is activated, and plant productivity can be improved. The operation of plant-growth promotion, which a high concentration of 02-dissolved water shows, can be considered as follows. First, when a high concentration of 02-dissolved water obtained by the present apparatus is sprayed onto a plant, a concentration gradient occurs between the outer periphery and the interior of a plant leaf, and 02 is diffused and taken into the plant, because the concentration of the 02-dissolved water is higher than the concentration of 02 dissolved in water under oxygen partial pressure of atmospheric pressure. 02 is consumed for plant respiration by which energy necessary for its life is obtained. In more detail, ATP is generated when 18 the electrons of NADH and FADH2 generated in glycolysis, fatty-acid oxidation, citric acid cycles, etc. , are transferred to 02 through a series of electron transmitters. The biosynthesis of biopolymers and the progression of reactions that require energy cannot be achieved before they are conjugated with this ATP. Therefore, the supply of 02 promotes the biosynthesis of various biopolymers and other metabolism, and plant productivity is improved. In photorespiration reactions that exist in a plant, 02 and C02 are competitive, when viewed from their substrates, with respect to ribulosebisphosphate carboxylase, which is a C02-fixing enzyme, and one of them obstructs a reaction in which the substrate of the other one participates. In other words, photorespiration is busy when a plant receives light under the gaseous-phase condition of a high concentration of 02, and, in some kinds of plants, this causes a reduction in production achieved by the photosynthesis. Therefore, it is preferable to employ a method of atomizing and supplying 02-dissolved water to a plant during a dark period during which light does not strike the plant, or a method of replacing the water with C02-dissolved water described later, or a method of irrigating 02-dissolved water described later onto the plant. The operation of plant-growth promotion, which a high 19 concentration of N2-dissolved water shows, can be considered as follows. First, when a high concentration of N2-dissolved water obtained by the present apparatus is sprayed onto a plant, a concentration gradient occurs between the outer periphery and the interior of a plant leaf, and N2 is diffused and taken into the plant, because the concentration of the N2-dissolved water is higher than the concentration of N2 dissolved in water under nitrogen partial pressure of atmospheric pressure. N2 is reduced by nitrogenase, which is an N2-fixing enzyme, and is changed into ammonia interrelatedly with a living organism which lives together with plants and has nitrogen-fixing ability. Ammonia synthesizes organic nitrogen compounds, such as protein or nucleic acid, by a glutamine-glutamic acid synthesizing pathway or glutamic acid dehydrogenase. The synthesis of organic nitrogen compounds, such as protein or nucleic acid, is promoted by supplying N2, and plant productivity is improved. Next, a description will be given of the control mechanism of each apparatus part when troubles occur while the present apparatus is being operated. The second pressure gauge P2 disposed at the exit part of the hollow fiber membrane module MO is used to monitor the hydraulic pressure of C02-dissolved water in the spreader 6 from the exit part of the hollow fiber membrane module MO. The present apparatus is required to run 20 within the range where the mechanical strength of the hollow fiber membrane module MO is not impaired, and, because the dissolved water must be sprayed in a mist form, the present apparatus is operated normally within the range of 3 kgf/cm2 or more. The relief valve S disposed between the second pressure gauge P2 and the spreader 6 is used to lower hydraulic pressure up to a predetermined pressure when the hydraulic pressure exceeds the aforementioned range because of, for example, clogging of the spray member 61. That is, as soon as the hydraulic pressure of the second pressure gauge P2 exceeds the predetermined pressure, the relief valve S opens so as to lower the hydraulic pressure. Preferably, when the relief valve S is actuated as described above, the pressure pump P is stopped in response thereto. For depressurization, the hollow fiber membrane module MO may be provided with an exhaust passage through a control valve SV1 if necessary. The control unit controls each member of the present apparatus as follows. First, the control valve SV2 opens in relation to the pressure pump P, and a C02 gas is supplied while being pressurized from the outside of the hollow fiber membrane 3 and while causing raw water to flow to the inside of the hollow 21 fiber membrane 3 that constitutes the hollow fiber membrane module MO, thereby continuously producing C02-dissolved water. When the hydraulic pressure of the second pressure gauge P2 exceeds a predetermined upper limit for some reason while the C02-dissolved water is being sprayed, the relief valve S opens so as to lower the hydraulic pressure, and the pressure pump P reaches a stopped state, and the control valve SV2 reaches a closed state. Thereafter, the control valve SV1 opens for depressurization. The apparatus shown by the embodiment of Fig. 1 is one for producing and supplying a high concentration of C02-dissolved water suitable for plant growth. However, the present apparatus can produce a high concentration of 02-dissolved water and a high concentrat ion of N2- dissolved water suitable for plant growth, in addition to the C02-dissolved water. Fig. 3 is a view showing an example of an apparatus for producing 02-dissolved water suitable for plant growth and an example of a method of supplying the 02-dissolved water. The present apparatus of Fig. 3 is made up of almost the same apparatus members as those of the apparatus shown in the embodiment of Fig. 1, and is different from the apparatus of Fig. 1 in the fact that the apparatus of Fig. 3 has no relief valve S. 22 Additionally, the supply method of gas-dissolved water is different from that shown in the embodiment of Fig. 1. Referring to the method of supplying gas-dissolved water produced by the present apparatus, it is preferable to supply the gas-dissolved water from plant roots or from a section formed in the plant. In order to achieve this, it is preferable to employ a supply method according to which gas-dissolved water is sprayed to, for example, soil that supports a plant, and the gas-dissolved water can be absorbed from plant roots or from a section formed in the plant. Therefore, for example. Fig. 3 shows a situation where a drip irrigation device 7 is disposed under a plant. The gas-dissolved water does not need to be sprayed in a mist form on purpose. Therefore, the spray member 61 shown in the embodiment of Fig. 1 is not needed when the present apparatus is used. It is preferable to employ a method in which the box-like drip irrigation device 7 shown in Fig. 3, for example, is connected to the present apparatus, and gas-dissolved water is supplied therethrough. Therefore, there is little need to consider that clogging occurs in the drip irrigation device 7 while the gas-dissolved water is being supplied, and the relief valve S shown in Fig. 1 does not need to be necessarily disposed. The apparatus shown in the embodiment of Fig. 1 and that 23 shown in the embodiment of Fig. 3 are ones for producing gas-dissolved water by use of a single gas cylinder. As another embodiment of the present apparatus, a plurality of gas cylinders selected from among C02, 02, and N2 may be provided. Fig. 4 shows an example of a plant growing apparatus having a C02-gas cylinder 1 and an 02-gas cylinder 2 and an example of a method of supplying gas-dissolved water produced by the present apparatus. A first feature of the present apparatus is the fact that a C02-gas pipe and a 02-gas pipe are joined with each other at a halfway point, and are connected to the hollow fiber membrane module MO, and, in addition, control valves SV2 and SV3 are disposed in the C02-gas pipe and the 02-gas pipe, respectively, in front of the joined point. A second feature of the present apparatus is the fact that a pipe led from the exit part of the hollow fiber membrane module MO to the downstream side branches off into a pipe for C02-dissolved water and a pipe f or 02-dissolved water at a halfway point. Control valves SV4 and SV5 are respectively disposed in the pipes. In the present apparatus, the control valves SV4 and SV5 are connected to the corresponding spreader 6 and the corresponding drip irrigation device 7, respectively. Next, the control mechanism of the present apparatus will be described. When C02-dissolved water is produced and supplied 24 to a plant, the control valves SV2 and SV4 are controlled to be opened in response to the pressure pump P. On the other hand, when 02-dissolved water is produced and supplied to the plant, the control valves SV3 and SV5 are controlled to be opened in response to the pressure pump P. When the kind of gas-dissolved water is replaced with another on the way to the plant, the control valve SV1 is instantaneously opened in order to carry out flushing of the gas-dissolved water that has not yet been replaced. The control method of the other apparatus members is the same as that described in the embodiment of Fig. 1. Thus, according to the present apparatus, it is possible to produce a plurality of kinds of gas-dissolved water with a single apparatus and supply them to the plant if necessary. Therefore, it is possible to greatly improve handleability, convenience, etc. (Examples) A description will hereinafter be given of the plant growing method that uses gas-dissolved water produced by the plant growing apparatus of the present invention. However, this does not limit the present invention. (Example 1) MHF (three-layer composite hollow fiber) membrane module (made by Mitsubishi Rayon Co., Ltd.) was used as the hollow 25 fiber membrane module MO. Using the apparatus of Fig. 1, C02-dissolved water was sprayed in a mist form onto kenaf (Hibiscus cannabinus L.) that was sowed and sprouted, in the state of being illuminated with light (bright period 14 hours, dark period 10 hours, 24°C) at intervals of 30 minutes and for 60 seconds at a time during the bright period. This plant was grown for 18 days. The concentration of this C02-dissolved water was 2200 ppm. (Comparative example 1) Except that tap water instead of C02-dissolved water of Example 1 was used. Comparative example 1 was carried out in the same way as in example 1. Table 1 shows growth data regarding kenaf that was grown for 18 days concerning Example 1 and Comparative example 1. Numerals in the table each indicate an average value ± standard deviation regarding ten test specimens. [Table 1] Fresh weight (g) Dry weight (g) Ground-part dry weight (g) Underground-part dry weight (g) Seedling height (cm) Example 1 2.77±0.79 0.36±0.12 0.30±0.10 0.06±0.02 19.2±1.8 Comparative example 1 1.82±0.52 0.18±0.06 0.15±0.05 0.03±0.01 15.7±2.8 Significance test (t test) Undergone Undergone Undergone Undergone Undergone 26 From the data of Table 1, it was understood that plant growth is promoted when a high concentration of C02-dissolved water (2200 ppm) obtained by the plant growing apparatus of the present invention is intermittently atomized onto the plant (kenaf). Similar results were brought about in various plants, such as corn (Zea mays L.), radish (Raphanus sativus L. var. acanthiformis Makino), and spinach (Spinacia oleracea L.). Significant effects were also obtained in the case where 02-dissolved water and N2-dissolved water were intermittently atomized onto these plants. (Example 2) Using the apparatus of Fig. 3, 02-dissolved water was supplied from a drip irrigation device onto a radish that was sprouted, in the state of being illuminated with light (bright period 14 hours, dark period 10 hours, 24°C) at intervals of 30 minutes and for 60 seconds at a time during the bright period. This plant was grown for 18 days. The concentration of this 02-dissolved water was 70 ppm. (Comparative example 2) Except that tap water instead of the 02-dissolved water of Example 2 was used. Comparative example 2 was carried out in the same way as in Example 2. Table 2 shows growth data regarding a radish that was grown for 18 days concerning Example 27 2 and Comparative example 2 . Numerals in the table each indicate an average value ± standard deviation regarding eight test specimens. [Table 2] Fresh weight (g) Dry weight (g) Ground-part dry weight (g) Underground-par t dry weight (g) Example 2 3.66+0.75 0.37±0.11 0.33+0.10 0.04±0.02 Comparative example 2 2.55±0.70 0.23+0.06 0.20+0.06 0.03+0.01 Significance test (t test) Undergone Undergone Undergone Not undergone From the data of Table 2, it was understood that plant growth is promoted when a high concentration of 02-dissolved water (70 ppm) obtained by the plant growing apparatus of the present invention is intermittently irrigated on the plant (radish) . Similar results were brought about in various plants , such as corn, kenaf, and spinach. Significant effects were also obtained in the case where C02-dissolved water and N2-dissolved water were intermittently irrigated on these plants. The plant growing method and plant growing apparatus that use various highly concentrated gas-dissolved water according to the present invention can be applied widely to the fields of agriculture and forestry and to the general field of gardening. The present invention is suitable for an increase in the yield 28 of farm products, such as grains and vegetables, petals, fruit trees, woods, and greening trees, quality improvements, and flowering promotion. Additionally, the present invention exerts an excellent effect on the rooting of cuttings, the binding of graftings, the acclimation of tissue-culture seedlings, etc. As described above, according to the plant growing apparatus of the present invention, it is possible to produce only a necessary amount of various gas-dissolved water suitable for plant growth that has a higher concentration than a conventional apparatus and supply it to plants. Additionally, plant growth can be promoted by supplying a high concentration of gas-dissolved water produced by this apparatus to plants. 29 </div>

Claims

<div class="application article clearfix printTableText" id="claims"> WHAT WE CLAIM IS:

1. A plant growing method comprising a step of supplying C02 or 02 or N2 in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to an opposite side of the permeable membrane, a step of dissolving the C02 or the 02 or the N2 in the raw water so as to reach a predetermined concentration, and a step of intermittently atomizing resultant C02- or 02- or N2-dissolved water onto plants, thereby promoting plant growth.

2. The plant growing method as set forth in Claim 1, wherein C02- or 02- or N2-dissolved water obtained by dissolving C02 or 02 or N2 in raw water up to a saturated concentration in a pressurized state is atomized onto plants and wherein a atomizing time of the C02- or the 02- or the N2-dissolved water at a time is set to be sufficient for water adhering to a plant surface to begin to drop, and an atomizing interval of the C02- or 02-or N2-dissolved water is set to be sufficient for the water adhering to the plant surface to be dried.

3. A plant growing method comprising a step of supplying C02 or 02 or N2 in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to an 30 opposite side of the permeable membrane, a step of dissolving the C02 or the 02 or the N2 in the raw water so as to reach a predetermined concentration, and a step of intermittently irrigating resultant C02- or02- or N2-dissolved water onto plants, thereby promoting plant growth.

4. A plant growing apparatus capable of promoting plant growth by intermittently atomizing C02- or 02- or N2-dissolved water onto plants , the plant growing apparatus having a permeable membrane module in which C02 or 02 or N2 is supplied in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to an opposite side of the permeable membrane, the C02 or the 02 or the N2 being dissolved in the raw water so as to reach a predetermined concentration.

5. A plant growing apparatus capable of promoting plant growth by intermittently irrigating C02- or 02- or N2-dissolved water onto plants , the plant growing apparatus having a permeable membrane module in which C02 or 02 or N2 is supplied in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to an opposite side of the permeable membrane, the C02 or the 02 or the N2 being dissolved in the raw water so as to reach a predetermined concentration. 31

6. A plant growing apparatus;" capable of promoting plant growth by selectively performing either a step of intermittently atomizing C02- or 02- or N2-dissolved water onto plants or a step of intermittently irrigating C02- or 02- or N2-dissolved water onto plant s, the plant growing apparatus having a permeable membrane module in which C02 or 02 or N2 is selectively supplied in a pressurized state from one side separated with a permeable membrane that is permeable only to a gas and impermeable to a liquid while causing raw water to flow to an opposite side of the permeable membrane, the C02 or the 02 or the N2 being dissolved in the raw water so as to reach a predetermined concentration.

7. The plant growing apparatus of any one of Claim 4 through Claim 6, further comprising a second flow path separated from a first flow path leading to the plants provided on a downstream side of the permeable membrane module, and a switching valve for automatically opening the second flow path when pressure in the first flow path exceeds a predetermined value.

8. The plant growing apparatus of any one of Claim 4 through Claim 7, further comprising: a third flowpath by which the opposite side of the permeable membrane is connected to a gas tank, a gas circulation valve disposed at an exit side of the 32 gas tank, a pump for supplying the raw water to one side separated with the permeable membrane, and a control unit for controlling each apparatus part, wherein the control unit intermittently actuates the pump while controlling the gas circulation valve to be opened only when the pump is running.

9 . The plant growing apparatus as set forth in Claim 6, further comprising: a third flowpath by which the opposite side of the permeable membrane is connected to a plurality of gas tanks, a fourth flow path for forming an exhaust passage from the opposite side of the permeable membrane, a gas circulation valve disposed at each exit side of the plurality of gas tanks, an exhaust valve for opening and closing the fourth flow path, a pump for supplying the raw water to the opposite side of the permeable membrane, and a control unit for controlling each apparatus part, wherein the control unit includes: a first means for opening any one of the gas circulation valves for a predetermined time. 33 a second means for, after the predetermined time elapses, opening any one of the remaining gas circulation valves in a state where the exhaust valve is opened, and a third means for, after that, closing only the exhaust valve and continuing this state for a predetermined time. By the authorised AJ Park Per INTELLECTUAL PROPERTY OFFICE OF N.Z - 1 OCT 2002 RECEIVED 34 </div>