Method for producing plants containing gaba

Abstract

To provide a method for producing plants containing GABA at high concentration.SOLUTION: Provided is a method for producing plants containing GABA by using a spray cultivation device 1, in which the spray cultivation device 1 has: a cultivation box 2 which has planting holes 4, and has an internal space 3 in which roots of plants inserted into the planting holes 4 hang down; and a nozzle 6 which sprays nutritious liquid into the internal space 3 of the cultivation box 2, where a waste liquid port 5 is provided for a bottom part of the cultivation box 2, the device is constituted such that nutritious liquid which has been sprayed from the nozzle 6 and deposited on the bottom part of the cultivation box 2 is discharged from the waste liquid port 5, the method has: a step of fixedly planting plants into the planting holes 4; a step of spraying nutritious liquid from the nozzle 6 to cultivate plants; and a step of harvesting plants planted in the planting holes 4, and when a period from fixed planting to harvesting of plants is equally divided into three which are a cultivation early period, a cultivation middle period and a cultivation late period, a spray amount per day of nutritious liquid in the cultivation early period is larger than a spray amount per day of nutritious liquid in the cultivation middle period and the cultivation late period.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a plant containing GABA (γ-aminobutyric acid), and more particularly to a method for producing a plant capable of producing high concentrations of GABA by spray culture. [Background technology]

[0002] In recent years, functional ingredients contained in plants have been attracting attention due to the increasing health consciousness. GABA (γ-aminobutyric acid) is a non-protein amino acid that is said to have various effects such as lowering blood pressure, stabilizing the mind, promoting the secretion of growth hormone, and promoting memory and learning.

[0003] Various methods for producing plants and foods containing GABA have been proposed. For example, Patent Document 1 discloses a method for producing an edible plant containing GABA, Patent Document 2 discloses a method for producing soil-grown vegetables containing GABA and / or taurine, Patent Document 3 discloses a method for producing a dried takuan product containing GABA, and Patent Document 4 discloses a method for producing a tomato drink containing GABA. Patent Document 5 discloses a plant cultivation device that includes a cultivation box having a hollow root zone and sprays a nutrient solution in the form of a mist onto the root zone. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-89572 A [Patent Document 2] JP 2009-201477 A [Patent Document 3] JP 2015-159741 A [Patent Document 4] JP 2010-136710 A [Patent Document 5] International Publication No. 2019 / 069826 Summary of the Invention [Problem to be solved by the invention]

[0005] Although various methods for producing plants and foods containing GABA have been proposed, little research has been done on the method for producing plants containing high concentrations of GABA by focusing on the plant cultivation method itself. The present invention has been made in view of the above circumstances, and its purpose is to provide a method for producing plants containing high concentrations of GABA. [Means for solving the problem]

[0006] The method for producing the plant of the present invention, which can solve the above problems, is as follows. [1] A method for producing a plant containing GABA using an aeroponics cultivation apparatus, comprising: The spray culture apparatus includes: A cultivation box having a planting hole and an internal space into which the roots of a plant inserted into the planting hole hang down; A nozzle for spraying a nutrient solution into the internal space of the cultivation box, A waste liquid port is provided at the bottom of the cultivation box, and the nutrient solution sprayed from the nozzle and accumulated at the bottom of the cultivation box is discharged from the waste liquid port. Planting the plant in the planting hole; A step of cultivating the plant by spraying the nutrient solution from the nozzle; and harvesting the plant planted in the planting hole. A method for producing a plant, characterized in that, when the period from planting to harvest of the plant is divided into three equal periods, an early cultivation period, a middle cultivation period, and a late cultivation period, the amount of the nutrient solution sprayed per day in the early cultivation period is greater than the amount of the nutrient solution sprayed per day in the middle cultivation period and the late cultivation period. [2] The method for producing a plant according to [1], wherein the fertilizer component concentrations of the nutrient solution in the middle and later stages of cultivation are higher than the fertilizer component concentrations of the nutrient solution in the early stage of cultivation. [3] The method for producing a plant according to [1] or [2], wherein during the middle and later stages of cultivation, the amount of the nutrient solution sprayed per hour during the day is greater than the amount of the nutrient solution sprayed per hour at night. [4] The method for producing a plant described in any of [1] to [3], wherein the nutrient solution is sprayed continuously or intermittently from the nozzle during an early cultivation period, and the nutrient solution is sprayed intermittently from the nozzle during an intermediate cultivation period and a later cultivation period, and the spraying time per day from the nozzle during the early cultivation period is longer than the spraying time per day from the nozzle during the intermediate cultivation period and the later cultivation period. [5] The method for producing a plant according to [4], wherein when the nutrient solution is intermittently sprayed from the nozzle, the time for each spray interruption is 60 minutes or less. [6] The method for producing a plant according to [4] or [5], wherein the nutrient solution is intermittently sprayed from the nozzle for a single spray time of 10 seconds or more and 300 seconds or less. [7] The method for producing a plant according to any one of [1] to [6], wherein the plant containing GABA is a fruit vegetable. [8] The method for producing a plant according to any one of [1] to [7], wherein the plant containing GABA is a tomato. [9] The method for producing a plant described in [8], wherein the GABA content of the tomato fruit is 50 mg / 100 g or more. Effect of the Invention

[0007] According to the method for producing a plant of the present invention, a plant is grown by spray culture, and the conditions for supplying a nutrient solution are appropriately set according to the growth stage of the plant, thereby enabling the roots to develop to a high degree and promoting the production of GABA by applying stress to the plant, thereby enabling the production of a plant containing GABA at a high concentration. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 shows an example of an aerosol cultivation apparatus used in the present invention, and is a partially cutaway perspective view of the aerosol cultivation apparatus. [Diagram 2]In the examples, the daily changes in the conditions of the nutrient solution spray time ratio and fertilizer component concentration when tomatoes were grown by spray culture (standard conditions) are shown. [Diagram 3] In the examples, the daily changes in the conditions of the nutrient solution spray time ratio and fertilizer component concentration when tomatoes were grown by spray culture (high salt concentration conditions) are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention is a method for producing plants containing GABA (γ-aminobutyric acid) using a spray culture device. In spray culture, the roots of a plant are exposed to the air and a nutrient solution is supplied in the form of a mist, which is absorbed by the roots. Therefore, compared to soil culture or hydroponic culture, the contact of the roots with the nutrient solution is reduced, which increases the stress on the plant, and since the roots are exposed to the air, it is possible to strictly control the supply of the nutrient solution to the roots.

[0010] In plants, GABA is produced by the action of glutamate decarboxylase (GAD) on glutamate. When a plant is stressed by its growing environment, the pH in the cytoplasm can become acidic. In this case, when GAD works to produce GABA from glutamate, hydrogen ions are consumed, and the acidic pH in the cytoplasm caused by the production of GABA is alleviated.

[0011] In the plant production method of the present invention, the characteristics of spray culture are utilized, and the supply conditions of the nutrient solution are appropriately set according to the growth stage of the plant, so that the roots can be developed to a high degree, and the production of GABA can be promoted by applying stress to the plant. This makes it possible to produce a plant containing GABA at a high concentration. The plant production method of the present invention will be described in detail below.

[0012] The spray culture apparatus used in the present invention will be described with reference to Fig. 1. Fig. 1 shows a partially cutaway perspective view of the spray culture apparatus. Note that the spray culture apparatus used in the present invention is not limited to the form shown in the drawing.

[0013] The spray culture apparatus 1 has a cultivation box 2 with a planting hole 4 for planting a plant. The cultivation box 2 has an internal space 3, into which a nutrient solution is sprayed, filling the internal space 3 with the mist of nutrient solution. The planting hole 4 is provided on the top or side of the cultivation box 2. In FIG. 1, the planting hole 4 is provided on the top surface (the top surface formed in an inclined shape) of the cultivation box 2. The planting hole 4 communicates between the internal space 3 of the cultivation box 2 and the outside of the cultivation box 2.

[0014] A waste liquid outlet 5 is provided at the bottom (bottom surface) of the cultivation box 2. As a result, even if the nutrient solution sprayed into the internal space 3 of the cultivation box 2 coagulates and accumulates as excess liquid at the bottom of the cultivation box 2, the excess liquid is discharged from the waste liquid outlet 5 to the outside of the cultivation box 2. In other words, the cultivation box 2 is configured so that the nutrient solution sprayed from the nozzle 6 and accumulated at the bottom of the cultivation box 2 is discharged from the waste liquid outlet 5, and it is possible to prevent the nutrient solution from being substantially in a bulk liquid phase in the internal space 3 of the cultivation box 2. The nutrient solution discharged from the waste liquid outlet 5 may be discarded or may be collected and reused as nutrient solution.

[0015] A plant to be cultivated in the spray culture cultivation apparatus 1, i.e. a plant that produces GABA, is inserted into the planting hole 4, and the roots of the inserted plant hang down in the internal space 3. At least a part of the roots of the plant inserted into the planting hole 4 hangs down in the internal space 3 of the cultivation box 2. The plant may be inserted directly into the planting hole 4, or the plant may be placed in a pot with holes and then inserted into the planting hole 4. In the latter case, the roots of the plant placed in the pot with holes hang down through the holes in the pot into the internal space 3 of the cultivation box 2.

[0016] The roots of the plant inserted in the planting hole 4 preferably hang down from the upper half of the internal space 3 of the cultivation box 2, that is, preferably hang down from any point in the upper half of the internal space 3 of the cultivation box 2 as a starting point. This makes it possible to prevent the roots of the plant from coming into contact with the inner surface of the cultivation box 2, at least in the early stages of cultivation, and to expose the entire roots to an atmosphere of misted nutrient solution. In other words, in the early stages of cultivation, it is possible to prevent the roots of the plant inserted in the planting hole 4 from coming into contact with the bulk liquid phase nutrient solution.

[0017] The spray culture device 1 is provided with a nozzle 6 that sprays the nutrient solution into the internal space 3 of the cultivation box 2. The nozzle 6 may be provided in the internal space 3 of the cultivation box 2, or may be provided outside the cultivation box 2. In the latter case, the nozzle 6 is installed so that the nozzle for spraying the nutrient solution faces the internal space 3 of the cultivation box 2. In FIG. 1, the nozzle 6 is provided in the internal space 3 of the cultivation box 2.

[0018] The nutrient solution is a solution containing fertilizer components, and the fertilizer components contained in the nutrient solution may be appropriately set according to the plants to be cultivated in the spray culture cultivation device 1. Examples of the fertilizer components include nitrogen, phosphoric acid, potassium, etc. The nutrient solution can be conveniently prepared by diluting a commercially available liquid fertilizer with water as appropriate.

[0019] The nozzle 6 is preferably installed so that the nozzle orifice faces an angle of 30° or less with respect to the horizontal direction, more preferably 20° or less, even more preferably 10° or less, and even more preferably 5° or less. It is particularly preferable that the nozzle 6 is installed so that the nozzle orifice faces the horizontal direction. By installing the nozzle 6 in this manner, the nutrient solution sprayed from the nozzle 6 is easily spread over a wide range of the internal space 3 of the cultivation box 2.

[0020] As the nozzle 6, a single-fluid nozzle or a two-fluid nozzle may be used. A single-fluid nozzle is a nozzle that sprays only the nutrient solution, while a two-fluid nozzle is a nozzle that sprays the nutrient solution mixed with compressed gas (e.g., air or carbon dioxide gas). It is preferable to use a single-fluid nozzle as the nozzle 6, so that when the nutrient solution is sprayed into the internal space 3 of the cultivation box 2, the mist of nutrient solution is not diluted by the gas ejected from the nozzle 6, and the nutrient solution can be filled in a mist of high concentration.

[0021] The average particle diameter of the nutrient solution sprayed from the nozzle 6 is preferably 5 μm or more, more preferably 10 μm or more, and is preferably 50 μm or less, and more preferably 30 μm or less. By spraying the nutrient solution in this manner, the nutrient solution is more likely to exist in a mist form in the cultivation box 2, and the sprayed nutrient solution is prevented from coagulating in a short period of time, making it less likely for the nutrient solution to accumulate as excess liquid at the bottom of the cultivation box 2. The average particle diameter described here means the Sauter mean particle diameter when the particle diameter distribution of droplets of the nutrient solution sprayed from the nozzle is measured using a laser diffraction particle size distribution measuring device at a point 30 cm away from the tip of the nozzle.

[0022] The cultivation box 2 has a longitudinal direction and a transverse direction in the horizontal direction, and the nozzle 6 is preferably installed so that the nozzle orifice faces the longitudinal direction of the cultivation box 2. The nozzle 6 is also preferably installed in the internal space 3 of the cultivation box 2. By installing the nozzle 6 in this manner, the nutrient solution sprayed from the nozzle 6 is more likely to spread over a wide area in the longitudinal direction of the cultivation box 2.

[0023] A plurality of planting holes 4 are arranged in a line in the longitudinal direction of the cultivation box 2, and preferably form a row of planting holes 4, and a plurality of rows of planting holes 4 are arranged in the transverse direction of the cultivation box 2. In addition, in a plan view of the cultivation box 2 seen from above, it is preferable that the nozzle 6 is arranged between adjacent rows of planting holes 4, and the nozzle 6 is installed so that the nozzle 6 faces the longitudinal direction of the cultivation box 2. By arranging the nozzle 6 in this manner, it becomes difficult for the nutrient solution sprayed from the nozzle 6 to directly hit the roots of the plants, and it becomes easy to uniformly fill the internal space 3 of the cultivation box 2 with the nutrient solution in a mist form. It is preferable that a plurality of nozzles 6 are arranged in a line in the longitudinal direction of the cultivation box 2. In FIG. 1, in a plan view of the cultivation box 2 seen from above, four rows of planting holes 4 (rows in which a plurality of planting holes 4 are arranged in the longitudinal direction) are arranged in a line in the transverse direction, and a row of nozzles 6 (rows in which a plurality of nozzles 6 are arranged in the longitudinal direction) is arranged between the two central rows of planting holes 4 in the transverse direction. In other words, two rows of planting holes 4 are arranged on each side of the row of nozzles 6. The nozzle 6 may be one that sprays the nutrient solution toward one side in the longitudinal direction of the cultivation box 2, or may be one that sprays the nutrient solution toward one side and both sides in the longitudinal direction of the cultivation box 2.

[0024] The supply pipe 7 for supplying the nutrient solution to the nozzle 6 may be inserted into the internal space 3 from the top surface of the cultivation box 2, from the bottom surface, or from the side surface. In FIG. 1, the supply pipe 7 for the nutrient solution is inserted into the internal space 3 from the top surface of the cultivation box 2, and the nozzle 6 is installed at the bottom of the supply pipe 7.

[0025] The spray culture apparatus 1 may be installed outdoors, or may be installed indoors in a vinyl greenhouse or the like. The spray culture apparatus 1 may be installed in a location exposed to sunlight, or may be installed under artificial light.

[0026] The plant production method of the present invention produces a plant containing GABA using the spray culture cultivation apparatus described above, and includes a step of planting the plant in a planting hole (planting step), a step of cultivating the plant by spraying a nutrient solution from a nozzle (cultivation step), and a step of harvesting the plant planted in the planting hole (harvesting).

[0027] In the planting step, a plant is planted in a planting hole of the spray culture apparatus. A seedling grown in advance from a seed is planted in the planting hole. The method of growing the seedling is not particularly limited, and may be a known method. The seedling may be planted directly in the planting hole, or the seedling may be placed in a pot with holes and inserted into the planting hole. In the planting step, it is preferable to plant the plant in the planting hole so that the roots of the plant do not touch the bottom surface of the cultivation box.

[0028] The type of plant planted in the planting hole is not particularly limited as long as it contains GABA at the harvesting stage in the harvesting process. The plant planted in the planting hole may or may not contain GABA at the time of planting. In addition, the plant containing GABA is preferably edible in consideration of the efficacy of GABA (for example, blood pressure lowering effect), and as an edible plant, vegetables or grains are preferable, and vegetables are more preferable. Examples of vegetables include fruit vegetables, leafy stem vegetables, root vegetables, etc., and the vegetables contained in each of these categories are determined by the Japanese Standard Product Classification of the Ministry of Internal Affairs and Communications. In addition, since GABA is contained more in fruits, leaves, and stems than in roots, fruit vegetables or leafy stem vegetables are preferable, and since GABA is contained in particular in fruits, fruit vegetables are more preferable. Among fruit vegetables, tomatoes are particularly preferable because they contain a lot of GABA. Tomatoes may be large or medium-sized tomatoes or cherry tomatoes.

[0029] In the cultivation process, the nutrient solution is sprayed from a nozzle installed in the spray culture cultivation device to cultivate the plant planted in the planting hole. The plant is cultivated under conditions that allow photosynthesis. The light source for photosynthesis may be sunlight or artificial light. The growth conditions, such as temperature, humidity, and atmosphere outside the spray culture cultivation device, may be set appropriately depending on the type of plant.

[0030] When the plant has grown to the harvest stage in the cultivation step, the plant planted in the planting hole is harvested in the harvesting step. The plant may be harvested in whole or in part, such as the fruit, leaves, stem, or roots.

[0031] In the plant production method of the present invention, when the period from plant planting to harvest is divided into three equal parts, an early cultivation period, a middle cultivation period, and a late cultivation period, the amount of nutrient solution sprayed per day in the early cultivation period is set to be greater than the amount of nutrient solution sprayed per day in the middle cultivation period and the late cultivation period. Hereinafter, the period from planting to harvest is referred to as the "cultivation period."

[0032] The cultivation period is divided into early, middle, and late cultivation periods as follows: If the cultivation period (number of days) is a multiple of 3, the number of days in the cultivation period is divided into thirds each to define the early, middle, and late cultivation periods. If the cultivation period (number of days) is a multiple of 3 plus 1, the early, middle, and late cultivation periods are defined so that the number of days in the mid-cultivation period is one day more than the early and late cultivation periods. If the cultivation period (number of days) is a multiple of 3 plus 2, the early, middle, and late cultivation periods are defined so that the number of days in the early, middle, and late cultivation periods is one day more than the mid-cultivation period. Note that when the harvest period for a single plant, such as fruit vegetables, spans multiple days, the first day of harvest is regarded as the harvest date (i.e. the last day of the cultivation period).

[0033] The amount of nutrient solution sprayed per day for each period represents the average amount sprayed. In other words, the amount of nutrient solution sprayed per day for each period is calculated by dividing the total amount of nutrient solution sprayed in each period by the number of days in each period.

[0034] As described above, by setting the amount of nutrient solution sprayed per day in the early, middle, and late stages of cultivation, plants containing a high concentration of GABA can be produced. Increasing the amount of nutrient solution sprayed per day in the early cultivation period allows the roots to develop to a high level. Since the roots are underdeveloped in the early cultivation period, the amount of spray is increased to improve the efficiency of collection of nutrient solution from the roots. In spray culture, unlike soil culture and hydroponic culture, the roots of plants cannot obtain nutrients unless they collect the nutrient solution present in a mist. Therefore, the lateral roots and root hairs develop to be able to actively collect the nutrient solution present in a mist, and roots with a large surface area are formed. In the early cultivation period, spraying a larger amount of nutrient solution allows the lateral roots and root hairs to develop more, which increases the efficiency of nutrient absorption by the roots and further promotes the development of the lateral roots and root hairs. In addition, in spray culture, the roots are exposed to the air, which promotes oxygen uptake and improves the plant's respiration rate. As a result, the absorption of nutrients and water is promoted, and the stomatal aperture is maintained, which also leads to an improvement in the photosynthesis rate. On the other hand, by reducing the amount of nutrient solution sprayed per day in the middle and late stages of cultivation, the plant can be stressed and the production of GABA can be promoted. By forming highly developed roots in the early stage of cultivation, the plant has excellent GABA production ability. In the middle stage of cultivation, the roots are already formed, so the amount of nutrient solution necessary to maintain root activity and promote growth is sprayed without excess, and in the late stage of cultivation, the amount of spray is precisely controlled to appropriately stress the plant without causing fatal damage or reducing production. In spray culture, the contact between the roots and the nutrient solution is suppressed compared to soil culture and hydroponic culture, making the plant more susceptible to stress, but by reducing the amount of nutrient solution sprayed per day in the middle and late stages of cultivation, the plant is further stressed and the production of GABA is promoted. In spray culture, the roots are exposed to the air, so the supply of nutrient solution to the roots can be precisely controlled, and effective stress cultivation can be achieved while avoiding damage to the plant.

[0035] It is preferable to increase the amount of nutrient solution sprayed per day during the first 5 to 15 days of the pre-cultivation period (i.e., between the 0th and 5th days of cultivation at the shortest, and between the 0th and 15th days of cultivation at the longest). For example, it is preferable to increase the amount of nutrient solution sprayed per day during the first 10 days of the pre-cultivation period than the amount of nutrient solution sprayed per day during the subsequent cultivation period. This allows the roots to develop to a higher degree. The amount of nutrient solution sprayed per day during the first 10 days of the pre-cultivation period is calculated by dividing the total amount of nutrient solution sprayed during the first 10 days of the pre-cultivation period by 10, the number of days. The amount of nutrient solution sprayed per day during the other periods is calculated in the same manner. It is more preferable that the amount of nutrient solution sprayed per day during the first 10 days of the pre-cultivation period is greater than the amount of nutrient solution sprayed per day during the subsequent pre-cultivation period.

[0036] The amount of nutrient solution sprayed per day during the middle cultivation period may be the same as or different from the amount of nutrient solution sprayed per day during the later cultivation period.

[0037] It is easier to adjust the amount of nutrient solution sprayed per day in each period by changing the spray time from the nozzle rather than changing the amount of nutrient solution sprayed (instantaneous spray amount) from the nozzle. In this case, it is preferable to set the time when the nutrient solution is sprayed from the nozzle and the time when it is not sprayed, and to keep the amount of nutrient solution sprayed from the nozzle substantially constant without changing it. This makes it easy to arbitrarily change the amount of nutrient solution sprayed per day. In this case, it is preferable that the nutrient solution is sprayed continuously or intermittently from the nozzle in the early cultivation period, and the nutrient solution is sprayed intermittently from the nozzle in the middle and late cultivation periods, and the spray time from the nozzle in the early cultivation period is longer than the spray time from the nozzle in the middle and late cultivation periods. The spray time of the nutrient solution in the middle cultivation period may be the same as or different from the spray time of the nutrient solution in the late cultivation period.

[0038] The daily spraying time of the nutrient solution in each period represents the average spraying time. In other words, the daily spraying time of the nutrient solution in each period is calculated by dividing the total spraying time of the nutrient solution in each period by the number of days in each period.

[0039] When the nutrient solution is intermittently sprayed from the nozzle, the time for one spray interruption is preferably 60 minutes or less. By setting the time for one spray interruption in this manner, it becomes easier to maintain the state in which the nutrient solution is present in the form of mist in the internal space of the cultivation box. The time for one spray interruption is more preferably 40 minutes or less, and even more preferably 30 minutes or less. The lower limit of the time for one spray interruption is not particularly limited, and may be, for example, 20 seconds or more, 30 seconds or more, or 1 minute or more.

[0040] When the nutrient solution is intermittently sprayed from the nozzle, the spray time for each spray is preferably 10 seconds or more. By spraying the nutrient solution from the nozzle in this manner, it becomes easy to fill a wide range of the internal space of the cultivation box with the nutrient solution in a mist form. On the other hand, when the nutrient solution is intermittently sprayed from the nozzle, the spray time for each spray is preferably 300 seconds or less, more preferably 240 seconds or less, and preferably 120 seconds or less. This makes it difficult for the nutrient solution sprayed from the nozzle to aggregate and accumulate as excess liquid at the bottom of the cultivation box, and also reduces the amount of excess liquid that accumulates at the bottom of the cultivation box.

[0041] In the middle and late stages of cultivation, the spray time ratio when the nutrient solution is intermittently sprayed from the nozzle is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less. This makes it difficult for the nutrient solution sprayed from the nozzle to aggregate and accumulate as excess liquid at the bottom of the cultivation box, and also reduces the amount of excess liquid that accumulates at the bottom of the cultivation box. On the other hand, in the middle and late stages of cultivation, the spray time ratio when the nutrient solution is intermittently sprayed from the nozzle is preferably 1% or more, more preferably 3% or more, and even more preferably 5% or more. This makes it easier to maintain the nutrient solution in a mist state in the internal space of the cultivation box. The spray time ratio is calculated by dividing the average daily spray time (unit: hour) of the nutrient solution in each section by 24.

[0042] In the early cultivation stage, it is preferable to continuously spray the nutrient solution from the nozzle for the first 1 to 7 days (i.e., from day 0 to day 1 of cultivation at the shortest, and from day 0 to day 7 of cultivation at the longest). After this, it is preferable to intermittently spray the nutrient solution from the nozzle. By continuously spraying the nutrient solution from the nozzle in the early cultivation stage, it becomes easier to develop the roots to a higher level.

[0043] In the middle and late stages of cultivation, it is preferable to spray a larger amount of nutrient solution during the day than during the night. Specifically, in the middle and late stages of cultivation, it is preferable that the amount of nutrient solution sprayed per hour during the day is greater than the amount of nutrient solution sprayed per hour during the night. By spraying the nutrient solution in this way, stomatal blockage is suppressed during the day, photosynthesis can be promoted, and stronger stress can be applied at night.

[0044] In the pre-cultivation period, it is preferable to make the amount of nutrient solution sprayed per hour during the day greater than the amount of nutrient solution sprayed per hour during the night, except for the first 15 days. During the first 15 days of the pre-cultivation period, the amount of nutrient solution sprayed per hour during the day may be greater than the amount of nutrient solution sprayed per hour during the night, or the amount of nutrient solution sprayed per hour during the day may be the same as the amount of nutrient solution sprayed per hour during the night. As described above, it is preferable to spray the nutrient solution continuously during the pre-cultivation period, and in this case, the amount of nutrient solution sprayed per hour during the day is the same as the amount of nutrient solution sprayed per hour during the night.

[0045] The amount of nutrient solution sprayed per hour during the daytime is calculated by dividing the total amount of nutrient solution sprayed from sunrise to sunset in each period by the time from sunrise to sunset in each period. The amount of nutrient solution sprayed per hour during the nighttime is calculated by dividing the total amount of nutrient solution sprayed from sunset to sunrise in each period by the time from sunset to sunrise in each period.

[0046] During the middle and later stages of cultivation, it is preferable that the amount of nutrient solution sprayed per hour during the day is greater than the amount of nutrient solution sprayed per hour during the night. It is preferable that the amount of sprayed is greater during the day than at night on 60% or more days of each period, more preferably on 80% or more days of each period, and even more preferably on all days of each period.

[0047] The fertilizer component concentration of the nutrient solution sprayed from the nozzle is preferably changed appropriately according to the growth stage of the plant. Specifically, the fertilizer component concentration of the nutrient solution in the middle and late cultivation stages is preferably higher than that in the early cultivation stage. By changing the fertilizer component concentration of the nutrient solution in this way, the amount of GABA produced can be increased in the middle and late cultivation stages. From the viewpoint of producing a plant with a higher GABA content, it is more preferable to make the fertilizer component concentration of the nutrient solution in the late cultivation stage higher than that in the middle cultivation stage.

[0048] The fertilizer component concentrations of the nutrient solution can be determined, for example, as the concentrations of the three elements of fertilizer: nitrogen, phosphorus, and potassium (the total content of each component by mass). The nitrogen, phosphorus, and potassium contents of commercially available fertilizers are indicated, and the fertilizer component concentrations of the nutrient solution can be determined based on this.

[0049] The fertilizer component concentration of the nutrient solution may be determined using electrical conductivity (EC) as an index. In the agricultural field, electrical conductivity is used as an index of fertilizer component concentration, so electrical conductivity may be used as an index of fertilizer component concentration of the nutrient solution. By using electrical conductivity as an index of fertilizer component concentration, the fertilizer component concentration of the nutrient solution can be easily determined. In this case, it is preferable that the electrical conductivity of the nutrient solution in the middle and later stages of cultivation is higher than the electrical conductivity of the nutrient solution in the early cultivation stage.

[0050] The fertilizer component concentration in the nutrient solution during each period can be determined by dividing the integrated value of the fertilizer component concentration for each day during each period by the number of days in each period.

[0051] According to the method for producing a plant of the present invention, a plant containing GABA at a high concentration can be harvested. As a plant containing GABA, fruit vegetables are preferred, and tomatoes are more preferred. When the plant containing GABA is a tomato, the GABA content (FW: fresh weight) of the tomato fruit can be, for example, 50 mg / 100 g or more, 60 mg / 100 g or more, or 70 mg / 100 g or more. The content can be further increased, and can be 100 mg / 100 g or more, 120 mg / 100 g or more, or 150 mg / 100 g or more. The upper limit of the GABA content of the tomato fruit is not particularly limited, and can be, for example, 500 mg / 100 g or less, 400 mg / 100 g or less, 300 mg / 100 g or less, or 200 mg / 100 g or less. EXAMPLES

[0052] The present invention will be described in more detail below by showing examples, but the scope of the present invention is not limited to these examples.

[0053] (1)Cultivation method Tomato seedlings (Takii Seeds, Frutica (registered trademark)) were planted in a spray culture device installed in a vinyl greenhouse, and the tomatoes were grown in spray culture by spraying nutrient solution (Sumitomo Chemical, Hi-Tempo Ar+Cu) from a nozzle installed in the cultivation box of the spray culture device, and the fruits were harvested. The nutrient solution sprayed from the nozzle was appropriately diluted to change the electrical conductivity (EC) in the range of 1.4 dS / m to 10.0 dS / m, thereby adjusting the fertilizer component concentration of the nutrient solution. The pH of the nutrient solution was adjusted to 5.8 by adding a pH adjuster (OAT Agrio). The fertilizer component concentration of the nutrient solution was basically increased according to the growth of the tomatoes (number of cultivation days). Two conditions of the fertilizer component concentration (salt concentration) of the nutrient solution were examined: a standard case (Figure 2) and a case where the fertilizer component concentration (salt concentration) was increased (Figure 3). The nutrient solution was sprayed continuously or intermittently from the nozzle, and the spray time ratio was appropriately changed according to the growth (number of days of cultivation) of the tomatoes as shown in Figs. 2 and 3, and the spray time ratio was changed between daytime and nighttime. When the nutrient solution was sprayed intermittently, the spray time for one time was set between 30 and 60 seconds, and the spray interruption time for one time was set between 60 and 870 seconds. Basically, the spray time ratio was reduced according to the growth (number of days of cultivation) of the tomatoes. In addition, the spray time was set so that the spray time ratio during the daytime was greater than the spray time ratio during the nighttime, except for the early stage of cultivation (immediately after planting). The amount of spray when the nutrient solution was sprayed from the nozzle was constant. As a comparative control, tomato seedlings (manufactured by Takii Seed Co., Ltd., Frutica (registered trademark)) were grown in soil or drip cultivation with coconut shells, and the fruits were harvested.

[0054] (2)Measurement method (2-1) Fruit weight Ten tomato fruits were harvested from each of the cultivation methods: spray culture (standard), spray culture (high salt concentration), soil culture, and drip coconut shell cultivation, and their weights were measured to determine the weight of each fruit.

[0055] (2-2) Sugar content The fruit slices used to measure fruit weight were placed in a 50 mL centrifuge tube, homogenized, and then centrifuged. The resulting supernatant was measured using a pocket sugar-acidity meter (Atago Co., Ltd., PAL-BX ACID3) to determine the sugar content.

[0056] (2-3)GABA content The supernatant used to measure the sugar content was diluted 10-fold and measured using a functional amino acid simple measurement set (GABA Miel (registered trademark) manufactured by Enzyme Sensor Co., Ltd.) to determine the GABA content per 100 g FW of tomato fruit.

[0057] (3) Results The results are shown in Table 1. The tomatoes grown by spray culture had a higher GABA content than those grown in soil or drip coconut shell. The GABA content per 100gFW of tomatoes grown by spray culture (standard) was 2.5 times that of those grown in soil and 5.0 times that of those grown in drip coconut shell. In terms of the GABA content per tomato, tomatoes grown by spray culture (standard) had 2.3 to 3.8 times more GABA than tomatoes grown in soil or drip coconut shell. Comparing the sugar content, tomatoes grown by spray culture (standard) had 1.3 to 1.4 times more sugar than tomatoes grown in soil or drip coconut shell, indicating that GABA is specifically produced in plants by spray culture.

[0058] When comparing spray culture where the fertilizer concentration (salt concentration) of the nutrient solution is standard with that where it is high, it was found that cultivation with a high salt concentration further increased the GABA content.Tomatoes grown with spray culture (high salt concentration) had 2.2 times the GABA content per 100gFW and 1.3 times the GABA content per tomato compared to tomatoes grown with spray culture (standard).

[0059] [Table 1] [Explanation of symbols]

[0060] 1: Spray cultivation equipment 2: Cultivation box 3: Interior space 4: Planting hole 5: Waste water outlet 6: Nozzle 7: Supply pipe

Claims

1. 1. A method for producing a plant containing GABA using an aeroponics system, comprising: The spray culture apparatus includes: A cultivation box having a planting hole and an internal space into which the roots of a plant inserted into the planting hole hang down; A nozzle for spraying a nutrient solution into the internal space of the cultivation box, A waste liquid port is provided at the bottom of the cultivation box, and the nutrient solution sprayed from the nozzle and accumulated at the bottom of the cultivation box is discharged from the waste liquid port. Planting the plant in the planting hole; A step of cultivating the plant by spraying the nutrient solution from the nozzle; and harvesting the plant planted in the planting hole. A method for producing a plant, characterized in that, when the period from planting to harvesting of the plant is divided into three equal parts, an early cultivation period, a middle cultivation period, and a late cultivation period, the amount of the nutrient solution sprayed per day in the early cultivation period is greater than the amount of the nutrient solution sprayed per day in the middle cultivation period and in the late cultivation period.

2. 2. The method for producing a plant according to claim 1, wherein the fertilizer component concentrations of the nutrient solution in the middle and later stages of cultivation are higher than the fertilizer component concentrations of the nutrient solution in the early stage of cultivation.

3. 2. The method for producing a plant according to claim 1, wherein the amount of the nutrient solution sprayed per hour during the day is greater than the amount of the nutrient solution sprayed per hour during the middle and later stages of cultivation.

4. In the early cultivation stage, the nutrient solution is sprayed continuously or intermittently from the nozzle, and in the middle and late cultivation stages, the nutrient solution is sprayed intermittently from the nozzle; 2. The method for producing a plant according to claim 1, wherein the spraying time per day from the nozzle in the early cultivation stage is longer than the spraying time per day from the nozzle in the middle cultivation stage and the late cultivation stage.

5. 5. The method for producing a plant according to claim 4, wherein the nutrient solution is intermittently sprayed from the nozzles, and one spray interruption period is 60 minutes or less.

6. 5. The method for producing a plant according to claim 4, wherein the nutrient solution is intermittently sprayed from the nozzle for a single spray time of 10 seconds or more and 300 seconds or less.

7. 2. The method for producing a plant according to claim 1, wherein the plant containing GABA is a fruit vegetable.

8. 2. The method of claim 1, wherein the plant containing GABA is a tomato.

9. 9. The method for producing a plant according to claim 8, wherein the GABA content in the tomato fruit is 50 mg / 100 g or more.

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