Photosynthetic plant growth control method and photosynthetic plant growth control device

Abstract

Provided is a photosynthetic plant growth control method capable of effectively regulating the growth of photosynthetic plants. 【Solution means】Irradiation with main light (such as sunlight, artificial light, etc.), which is light stronger than the light compensation point for photosynthesis of the photosynthetic plant to be cultivated, and additional signal light, which has a light intensity smaller than that of the main light, is light weaker than the light compensation point, and the light intensity varies temporally (such as only random vibration light, a combination of random vibration light and periodic vibration light, etc.) are performed. The irradiation of the additional signal light is performed simultaneously with the main light or during a time period when the main light is not irradiated. The additional signal light has a waveform formed so as not to have periodicity, and the action of causing photosynthesis is random vibration light having a lower level than that of additional signal light having periodicity (such as periodic vibration light).

Description

Technical Field

[0001] The present invention relates to, for example, a method for controlling the growth of photosynthetic plants capable of adjusting the flowering time of photosynthetic plants, and a photosynthetic plant growth control device.

Background Art

[0002] Plants synthesize carbohydrates essential for survival and growth using light energy with CO 2 and H 2 0 as raw materials. This is called photosynthesis. The carbohydrates produced by photosynthesis flow into and are consumed in the respective pathways of basal metabolism, which is converted into substances necessary for life maintenance, primary metabolism, which is converted into biomass necessary for growth, and specific metabolism (secondary metabolism), which is converted into antioxidants. Light is essential for photosynthesis, but at the same time, it causes physical and chemical damage at the cellular level. This is called light stress in plants. When plants sense light stress, they produce various antioxidants to protect cells from damage. Antioxidant production using the light stress response is being carried out.

[0003] The present applicant has disclosed an invention in which the light intensity of additional signal light is regularly changed in the applications according to Patent Documents 1 to 3 described below. Further, Patent Document 2 (paragraph 0021, etc.) discloses that when a plant suffers some damage to cells due to environmental stress such as strong light, the plant produces various antioxidants in a metabolic reaction to defend against, alleviate, and repair the damage.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a plant absorbs light, it undergoes light stress depending on the wavelength and intensity of the light. To repair cell damage caused by light stress, plants synthesize antioxidants such as ascorbic acid and polyphenols. Generally, light stress occurs with any light, but the shorter the wavelength, the stronger the light intensity, and the longer the irradiation time, the stronger it becomes. Generally speaking, light stress tends to become prominent by irradiation with light having a PPFD (photosynthetically active photon flux density, unit: μmol m-2 s-1) value of 200 or more.

[0006] Antioxidants such as ascorbic acid and polyphenols synthesized by plants subjected to light stress have medicinal effects and are thus useful for humans. And, an attempt has also been made to efficiently produce antioxidants in plants by utilizing light stress. However, when irradiating with strong light to cause light stress, there is a problem that the power consumption increases. Therefore, in order to reduce the power consumption, a method of causing light stress at a relatively small light intensity is desired. Furthermore, since plants have the ability to adapt to environmental changes, there is also a problem that the light stress effect gradually decreases when the same light stress continues.

[0007] An object of the present invention is to provide a method for controlling the growth of photosynthetic plants capable of effectively adjusting the growth of photosynthetic plants, and a device for controlling the growth of photosynthetic plants.

Means for Solving the Problems

[0008] The method for controlling the growth of photosynthetic plants according to the present invention is irradiating main light, which is light stronger than the light compensation point for photosynthesis of the photosynthetic plants to be cultivated, and irradiating additional signal light, the light intensity of which is smaller than that of the main light and weaker than the light compensation point, and the light intensity of which varies temporally, and the irradiation of the additional signal light is performed simultaneously with the main light or during a time period when the main light is not irradiated, The additional signal light has a waveform formed so as not to have periodicity, and is random vibration light with a lower photosynthesis-inducing effect than additional signal light with periodicity. The photosynthetic plant growth control device according to the present invention is a photosynthetic plant growth control device for irradiating main light for photosynthesis of photosynthetic plants to be cultivated, an additional light source that irradiates additional signal light in addition to the main light, and an irradiation light control unit capable of driving and controlling the additional light source. The light intensity of the additional signal light is relatively smaller than the main light and the light compensation point of the photosynthetic plant, and varies temporally. The additional signal light has a waveform formed so as not to have periodicity, and is random vibration light with a lower photosynthesis-inducing effect than additional signal light with periodicity. The growth of the photosynthetic plant is adjusted by irradiating the random vibration light.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a photosynthetic plant growth control method and a photosynthetic plant growth control device capable of effectively adjusting the growth of photosynthetic plants.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail.

[0012] <Photosynthetic Plant Growth Control Method> <<Outline of the Photosynthetic Plant Growth Control Method in the Present Embodiment>> As also disclosed in the aforementioned Patent Document 1, photosynthetic plants (hereinafter referred to as "plants") self-produce carbohydrates necessary for life maintenance and growth through photosynthesis. In photosynthesis, water (H 2 0) and carbon dioxide (CO 2 ) are used to produce glucose (C 6 H 12 O 6 ), which is a carbohydrate. For the reaction for production to proceed, light energy is indispensable. The light energy is absorbed by a pigment aggregate tissue called a light antenna.

[0013] This embodiment provides a plant growth control method in which light with irregularly changing light intensity is additionally irradiated in an environment where plants are grown by sunlight (natural light) or artificial light such as LEDs. When the additional light to be added (hereinafter sometimes referred to as "additional light") is light that irregularly changes the light intensity, the action of causing photosynthesis becomes low (weak), and the additional light induces light stress in cells. Then, the additional light promotes the conversion of photosynthetic products, carbohydrates, into antioxidants, thereby suppressing the plant growth process.

[0014] The inventors have discovered that in additional light with irregularly changing light intensity, the action of causing photosynthesis is lower than that of additional light with regularly changing light intensity. And the inventors have conceived of suppressing the plant growth process by using additional light with irregularly changing light intensity.

[0015] First, the growth of plants by main light will be described below, and then the growth suppression and the like by additional light (random vibration light, random light) with irregularly changing light intensity will be described. Furthermore, thereafter, the relationship between the inventions disclosed in the prior patent documents 1 to 3 and the unpublished applications by the applicant of the present application and this embodiment, and plant cultivation devices (plant growth control devices) and the like will be described.

[0016] <<Growth of Plants by Main Light>> Plants perform photosynthesis and respiration simultaneously. Photosynthesis absorbs carbon dioxide and releases oxygen. Respiration absorbs oxygen and releases carbon dioxide. The carbon dioxide absorption rate in photosynthesis (unit: μmolCO 2 m -2 s -1 ) depends on the light intensity (see Fig. 1), but the amount of carbon dioxide absorbed in respiration does not depend on the light intensity.

[0017] The carbon dioxide absorption rate in photosynthesis (μmolCO 2 m -2 s -1 ) and the carbon dioxide release rate in respiration (μmolCO 2 m -2 s -1) difference is the photosynthetic rate (μmolCO 2 m -2 s -1 ). The PPFD (Photosynthetic Photon Flux Density, described later) at which the photosynthetic rate becomes zero is the light compensation point (Figure 1). The value of the light compensation point varies depending on the type of plant.

[0018] The light intensity in photosynthesis is defined as the number of photons of light irradiated on the leaf surface per unit area per second. This is called Photosynthesis Photon Flux Density (hereinafter abbreviated as PPFD).

[0019] When water and carbon dioxide are sufficiently supplied, the glucose production amount increases proportionally to the PPFD up to a certain saturation value. The light intensity at which the glucose production amount saturates is defined as the photosynthetic saturation light intensity. To promote plant growth, light of about the photosynthetic saturation light intensity is required. The "light saturation point" in Figure 1 corresponds to the photosynthetic saturation light intensity.

[0020] When the irradiated light is below the photosynthetic saturation intensity, artificial light such as LED light may be irradiated to compensate for the lack of light. Compensating for light deficiency in this way is called "supplemental lighting". Supplemental lighting is a method of directly increasing photosynthesis. It is also possible to call the artificial light that directly increases photosynthesis "supplemental lighting".

[0021] In this embodiment, sunlight (natural light) and artificial supplemental light are referred to as "main light" for photosynthesis. This main light is light for directly causing or increasing photosynthesis. The main light is light emitted from sunlight, LEDs, etc., and is the light mainly responsible for photosynthesis.

[0022] <<Growth control by additional light (random vibration light)>> In this embodiment, auxiliary light different from the main light is artificially created and irradiated onto plants. This auxiliary light is referred to as "additional light". The irradiation of this additional light is performed at a predetermined time or period, details of which will be described later. The additional light in this embodiment is mainly light whose light intensity changes irregularly. The additional light in this embodiment is a kind of "additional signal light". Also, light whose light intensity changes irregularly can be referred to as, for example, "random vibration light" and the like.

[0023] FIG. 2 shows an example of a waveform related to additional signal light (random vibration light). The horizontal axis in FIG. 2 indicates time, and the vertical axis indicates light intensity. In FIG. 2, subsequent pulses are measured at intervals of T1 to T5 from the first pulse (the first rising edge of the signal). For the times T1 to T5, ···, Tn-1, Tn (n is a natural number), there is a relationship of T1≠T2≠T3≠T4≠T5≠···≠Tn-1≠Tn. That is, the pulses of the light intensity change intermittently at irregular time intervals. Note that, for example, some of the time intervals may coincide, such as T1 = T5. As shown in FIG. 2, for the random vibration light according to this embodiment, the lighting time for each time is fixed, but the non-lighting time between each time changes randomly.

[0024] In the experiments by the inventors and the like, when plants and the like are irradiated with additional signal light (random vibration light) that changes at such irregular time intervals, no effect of promoting photosynthesis (photosynthesis promotion effect) is observed, and the effect of giving light stress to plants (light stress effect) persists at a high level.

[0025] In the additional signal light disclosed in the above-mentioned Patent Documents 1 to 3, the light intensity changes periodically. In the case of such periodic vibration light, there is a photosynthesis promotion effect, and the light stress effect gradually decreases.

[0026] The additional signal light disclosed in the aforementioned Patent Documents 1 to 3 is periodic vibration light (periodic light) output so that the waveform in each period is common. In contrast, the additional signal light according to the present embodiment is light whose light intensity changes irregularly (random vibration light, random light). Further, the additional signal light (random vibration light, random light) according to the present embodiment is light that has a low effect of causing photosynthesis and is for suppressing the growth process of plants. And by irradiating with random vibration light, it is possible to adjust the growth of plants.

[0027] As described above, the inventors newly obtained the finding that by irradiating light whose light intensity changes irregularly (irregular additional signal light, random vibration light), the effect of causing photosynthesis becomes low (weak), and the additional light induces light stress in cells. In the present embodiment, such new findings by the inventors are utilized to promote the conversion of carbohydrates, which are photosynthesis products, into antioxidants and enable the suppression of the growth process related to plants. Further, in the present embodiment, it is possible to adjust growth according to the classification of plants (classification into short-day plants, long-day plants, and neutral plants).

[0028] Irradiation with random vibration light, which is additional signal light (hereinafter also referred to as "gene expression light"), does not necessarily have to stop during the irradiation of the main light, for example, but it is preferable to perform it so as to at least partially include a time zone in which the light intensity of the main light for photosynthesis is smaller than the light compensation point. The wavelength band of the additional signal light is preferably from 350 nm to 750 nm.

[0029] The random vibration light of the present embodiment is light whose intensity changes over time and is generated so that there is no periodicity or regularity in the time change. A method for generating random vibration light will be described later.

[0030] When the change in the light intensity irradiated on a plant is, for example, periodic, continuous, or gentle, the plant becomes accustomed to the resulting light stress, and the light stress effect weakens. Since the change in the light intensity in the random vibration light of the present embodiment is intermittent, irregular, and steep (because at least it is irregular among these conditions), the light stress can be sustained at a relatively high level. Also, the random vibration light of the present embodiment can sustain light stress with low power consumption. Specifically, the power consumption is 10 W or less per 1 ha of the area of the ground, floor, or wall where the plants are cultivated. Furthermore, since the random vibration light of the present embodiment promotes the conversion from carbohydrates to antioxidants, the growth (weight gain) rate of the plants decreases, and flowering can be suppressed.

[0031] Regarding the random vibration light of the present embodiment, there is no limitation on the value of PPFD (PPFD value), but it is considered desirable that it be 1.0 or less. There is also no limitation regarding the duty (the ratio of the time when it is Hi in one cycle of the pulse wave).

[0032] Furthermore, even if the additional signal light (periodic vibration light) disclosed in the above-mentioned prior patent documents 1 to 3 and the additional signal light (random vibration light) of the present embodiment are irradiated simultaneously, the light stress effect can be obtained. Also, even if the random vibration light is irradiated at a different time zone before or after the irradiation of the periodic vibration light, the light stress effect can be obtained. Furthermore, regardless of the time zone within a day when the random vibration light is irradiated, the light stress effect can be obtained. Also, the effect of irradiating the random vibration light continues even at night when the random vibration light is irradiated only during the daytime time zone (the time zone when the main light is brighter than the compensation point of the plants to be grown).

[0033] Furthermore, a regular signal buried in thermal noise can be detected in principle. That is, as disclosed by the applicant in the specification of Japanese Patent Application No. 2024-094162 (paragraphs 0037 to 0040, etc.), periodic vibration light irradiated simultaneously with main light such as sunlight can be detected (detected) in plants. And by detecting (detecting) the periodic vibration light, it is possible to improve the photosynthetic ability and sense sunlight in plants. However, an irregular signal (random vibration light) buried in thermal noise cannot be detected based on the principle of detection in plants. Hereinafter, the above-mentioned Japanese Patent Application No. 2024-094162 will be referred to as the "unpublished application".

[0034] <Relationship with the inventions disclosed in Prior Patent Documents 1 to 3 and the unpublished application> Subsequently, the relationship between the present embodiment and the inventions disclosed in Prior Patent Documents 1 to 3 and the unpublished application will be described. Hereinafter, the configuration of the additional light, the additional relaxation light, the mechanism of photosynthesis promotion by regular vibration light, and the growth regulation disclosed in the unpublished application will be described in this order.

[0035] <<Configuration of additional light>> First, in the inventions disclosed in Prior Patent Documents 1 to 3, the invention related to the unpublished application, and the plant growth control method (plant cultivation method) of the present embodiment, during the process of irradiating sunlight or artificial light as main light (main light) for photosynthesis, additional light is irradiated during an arbitrary cultivation period from sowing to harvesting. The additional light is either only additional signal light or a combination of additional signal light and light with a gradually changing light intensity (additional relaxation light). The additional signal light is periodic vibration light with a periodically varying light intensity and / or random vibration light with an irregular variation in light intensity.

[0036] <<Additional relaxation light>> The additional relaxation light has a sine-wave-like waveform as disclosed in Prior Patent Documents 1 to 3, and its basic period is 1 ms or more. When the period of the periodic additional signal light (periodic oscillating light) is 8 μs < T < 200 μs, the basic period of the additional relaxation light is 125 to 2 times or more the period T of the additional signal light. The additional relaxation light can also be described as light that exhibits a waveform with a smaller rate of change (light intensity change rate) related to the intensity gradient compared to the additional signal light. Also, regarding the additional relaxation light, when comparing it with the additional signal light using the waveform of one period, it can be described as light with a gentler overall light intensity change rate compared to the additional signal light. The additional relaxation light is light for mitigating the effects of side effects of the additional signal light (such as the growth of plants being suppressed by strong light stimulation) that relatively rapidly changes in intensity. Therefore, the temporal change of the additional relaxation light must be gentler than the temporal change of the light intensity of the additional signal light.

[0037] In this way, by irradiating plants with additional light obtained by combining periodic additional signal light (periodic oscillating light) with additional relaxation light, it is possible to further mitigate the light stress felt by plants compared to the case of irradiating with the additional signal light alone. That is, the additional light including periodic additional signal light is light that can, by combining the additional signal light and the additional relaxation light, improve the light stress reduction effect of the additional light as much as possible.

[0038] <<Mechanism of Photosynthesis Promotion by Regularly Oscillating Light>> Subsequently, the mechanism by which additional light (here, periodic oscillating light) whose light intensity (PPFD) periodically changes promotes photosynthesis will be described. The mechanism by which the additional light promotes photosynthesis is also described in the aforementioned Prior Patent Documents 1 to 3.

[0039] It is known that plants have a light integration function, and plants integrate the intensity and irradiation time of sunlight daily. When a decrease in PPFD (PPFD decrease) in the main light is detected by the integration function, the DNA in the chloroplasts of the plant issues an order to increase the production of chlorophyll in the light antenna. As a result, the light absorption amount increases and photosynthesis is promoted.

[0040] When using periodic oscillating light as the additional signal light, the differential function of detecting the light intensity change rate potentially possessed by plants is utilized. The pulse light (signal light) that repeats lighting and extinguishing at regular time intervals is the one that can most efficiently stimulate the differential function of plants. This pulse light (signal light) is the additional signal light. The additional signal light is the light included in the additional light. The additional signal light is irradiated onto plants either alone or together with the additional relaxation light.

[0041] The additional signal light (here, periodic oscillating light) is insufficient for photosynthesis compared to the main light. Therefore, plants recognize that they are temporarily in a state of photosynthetic starvation. When DNA detects the photosynthetic starvation state, in order to absorb more light necessary for photosynthesis, DNA issues an order to increase the production of chlorophyll. Furthermore, due to the additional signal light, DNA issues an order to control the opening and closing of stomata, which are the entrances and exits of the outside air, so that the amount of carbon dioxide absorbed increases. As a result, due to the irradiation of the additional pulse light, the light energy necessary for photosynthesis and the amount of carbon dioxide absorbed increase. That is, the periodic signal light functions as a trigger signal for causing DNA to issue an order to increase chlorophyll production and an order to control stomatal opening and closing. The effect of the additional signal light in such a concept is defined as the DNA trigger effect of the additional signal light.

[0042] The DNA trigger effect increases in proportion to the number of triggers per unit time but does not depend on the intensity of the trigger signal. If the time interval of the trigger signal becomes too short, the DNA trigger effect decreases. Also, the photosynthesis promotion effect by the additional light including the additional signal light can be obtained regardless of the value of the PPFD of the main light.

[0043] In addition, the effect of irradiating regular oscillating light continues even at night when the regular oscillating light is irradiated only during the daytime (the time zone when the main light is brighter than the compensation point of the plant to be grown).

[0044] <<Growth regulation disclosed in the unpublished application>> The above is the mechanism of photosynthesis promotion by regular vibration light, which is also described in Prior Patent Documents 1 to 3. However, as a result of the inventors' intensive research thereafter, as disclosed in the above-mentioned unpublished application, it has been found that the irradiation of an additional signal (here, periodic vibration light) is effective in suppressing the flowering of short-day plants. As shown in FIG. 4 (corresponding to FIG. 2 of the unpublished application), when the additional signal light hits the plant, the plant detects the sunlight (feels it as daytime). Such a function is realized by the plant having the function of a differential circuit related to light. As a result, the length of the dark period is shortened, and the effective day length (actual execution day length) combining sunlight and the additional signal light increases. For short-day plants, flowering and flower bud formation can be suppressed, and for long-day plants, flowering and flower bud formation can be promoted.

[0045] In FIG. 4, from the stage when sunset is approaching and the main light (here, sunlight) weakens (for example, after 16:00, which is 2 to 3 hours before sunset), the additional signal light (here, periodic vibration light) is irradiated in the evening until a predetermined period until sunrise. Also, when suppressing flower bud formation, it is possible to prevent a large amount of nutrients from being consumed for flower bud formation, promote the growth of individual leaves, grow the stem and increase the number of leaves. More specifically, due to the suppression of flowering, the harvestable period is extended for the cultivation period. Also, regarding the harvest timing, by extending the harvest period to the cool season in autumn, the quality of the plants targeted for flowering suppression is improved. Furthermore, regarding the harvest, an increase in yield can be expected due to the extension of the harvest period.

[0046] Figure 5 (corresponding to Figure 3 of the unpublished application) shows the basic waveform of the additional signal light (here, periodic oscillating light). In the example of Figure 3, the additional signal light shows a periodic sawtooth (also called "saw-shaped") waveform. The waveform of one period (ΔT) in the additional signal light has a waveform during the period (ΔTa) when the light intensity increases and a waveform during the period (ΔTb) when the light intensity decreases. The sum of the period (ΔTa) when the light intensity increases and the period (ΔTb) when the light intensity decreases is one period (ΔT). In Figure 3, the unit related to the light intensity on the vertical axis is an arbitrary unit (A.U.), and the unit related to time on the horizontal axis is μs.

[0047] Figure 6 (corresponding to Figure 4 of the unpublished application) shows an example of the time spectrum of the actual additional signal light (here, periodic oscillating light). Similar to Figure 5, the horizontal axis of the graph is time (μs) and the vertical axis is light intensity (A.U.). In the example of Figure 4, the period from the occurrence of the rising edge of the waveform to the occurrence of the next rising edge is one period (ΔT1~ΔTn, n is an integer of 1 or more). Here, let ΔT1 = ΔT2 = ΔT3 = ··· = ΔTn-1 = ΔTn = ΔT. The additional signal light is output-controlled so that the light intensity does not become 0 (zero) and the duty is 100% in each period (ΔT).

[0048] Figure 7 (corresponding to Figure 5 of the unpublished application) shows the content of the consideration comparing the reaction of plants by the irradiation of the additional signal light (here, periodic oscillating light) with the reaction of humans by high-altitude training. First, when a human (Human) undergoes high-altitude training, blood oxygen starvation occurs. In such a situation, the human body increases the blood oxygen concentration by the function of hemoglobin and improves the cardiopulmonary function.

[0049] In the case of a plant, when extremely weak light irradiation (EDL irradiation), such as additional signal light, is performed, photosynthesis starvation occurs. In such a situation, the plant increases the light harvesting efficiency and the photosynthesis rate by the action of chlorophyll. Here, "EDL" is an abbreviation for Extremely Dark Light.

[0050] When such a plant's survival crisis response is applied to short-day plants, as shown at the right end of FIG. 7, flowering can be suppressed. That is, when weak photosynthesis by additional signal light continues, a state of photosynthesis starvation occurs, and the plant feels as if it is daytime even in an environment darker than daytime. Then, in the plant, the effective sunlight hours increase, and the flowering of short-day plants is suppressed. Since the additional signal light is extremely weak light that causes weak photosynthesis, according to the plant cultivation method of the present embodiment and the plant cultivation apparatus (photosynthetic plant growth control apparatus) 10 described later, it is possible to adjust the growth of plants with low power consumption.

[0051] The additional signal light irradiation (periodic oscillating light irradiation) in the invention related to the unpublished application is for the purpose of flowering adjustment and is performed in an arbitrary time zone from near sunset to sunrise. This is because the inventors have discovered that plants have a function of perceiving a certain period of additional signal light as a light period, and this function is utilized. Due to such a plant perception function, the effective day length becomes longer. As a result, it becomes possible to suppress flowering in short-day plants and promote flowering in long-day plants.

[0052] Regarding such a sunlight detection mechanism (sunlight detection mechanism), it is possible to say that the following processes are carried out in chronological order. First, a weak vibration light (additional signal light) is irradiated in a state buried in strong light (main light). Subsequently, in the plant, signal processing is performed while changing the frequency of the reference wave. Further, the plant detects only the vibration light (additional signal light) and differentiates the detected signal. As a result, sunlight detection is performed. Also, such a sunlight detection mechanism can be presumed to have a function similar to that of a lock-in amplifier in the technical field of signal processing, as shown in, for example, FIG. 8 (corresponding to FIG. 6 of the unpublished application). In the technical field of signal processing, a lock-in amplifier detects a minute repetitive signal (alternating current) buried in noise.

[0053] The upper part of FIG. 8 shows the sunlight detection mechanism by the plant in order from the left. The frame in the lower part of FIG. 8 shows the functions of the lock-in amplifier in order from the left. Here, consider the case where a relatively strong light (here, the main light) and a weak vibration light (additional signal light, light of a certain period) are simultaneously irradiated on the plant, as shown in the upper left part of FIG. 8. Further, it is considered that the same function as when the reference wave in the lock-in amplifier is input occurs in the plant.

[0054] As shown in the lower part of FIG. 8, in the lock-in amplifier circuit, the input signal (f(t)=Asin(ωt)) and the reference signal (sin(ω 0 t)) are multiplied (multiplied), and from the trigonometric multiplication formula (Asin(ωt)xsin(ω 0 t)=(A / 2){cos(ω-ω 0 )-cos(ω+ω 0 )t}), a signal of (A / 2){cos(ω-ω 0 )-cos(ω+ω 0 )t} is generated. This signal becomes (A / 2){cos(0)-cos(2ω 0 )t} when the condition of the angular frequency is ω=ω 0 . Then, by a low-pass filter (LPF) (2ω 0) component is removed, and only the signal synchronized with the reference signal is detected. The detected signal (detection signal) becomes f(t)=(A / 2)sin(ωt).

[0055] As shown on the left side of the upper row in FIG. 8, in a plant irradiated with strong light (main light) and weak light (additional signal light, periodic vibration light), as shown on the right adjacent side, only the signal of the weak signal (additional signal light) is detected by the detection function (lock-in detection function) of the above lock-in amplifier. Further, as shown on the right adjacent side, a differential operation function is exhibited and converted into light of a certain intensity. Then, as shown from top to bottom on the lower right side of the figure, sunlight perception based on the obtained signal is performed, and the effective sunlight time in the plant becomes longer. As a result, it becomes possible to suppress flowering in short-day plants and promote flowering in long-day plants.

[0056] Regarding the reference wave in plants, the inventors presume that the plant itself emits a signal corresponding to the reference wave of the lock-in amplifier. That is, it is considered that the plant has a lock-in amplifier function. In other words, it means that the plant has a function (organ) for generating a reference wave and a path for transmitting a signal of a certain period detected by the lock-in amplifier to the gene. Regarding the location where lock-in detection is being performed, the inventors consider that it is one of photosynthetic pigments, pigments, and photoreceptor proteins.

[0057] <<Summary of the relationship with the inventions disclosed in Prior Patent Documents 1 to 3 and unpublished applications>> The inventions disclosed in Prior Patent Documents 1 to 3 and unpublished applications use EDL (extremely weak light, light with a PPDF value of about 0.01, for example) as light with a regular intensity waveform. And the invention according to Prior Patent Document 1 causes a plant to sense a photosynthetic starvation state by EDL. The invention according to Prior Patent Document 2 causes a plant to perform acquired trait inheritance by EDL. And the inventions according to Prior Patent Documents 1 and 2 cause a plant to increase chlorophyll, photosynthesis rate, and glucose. Further, the invention according to Prior Patent Document 3 enables the invention according to Prior Patent Document 1 to be applied to IoT and remote control.

[0058] In addition, for the invention related to the unpublished application, the EDL causes a plant to perform lock-in amplifier detection and sunlight perception, thereby increasing the effective sunlight time.

[0059] In contrast, in the plant growth control method of the present embodiment, as the EDL, instead of the periodic vibration light, or together with the periodic vibration light, for example, random vibration light as shown in FIGS. 2 and 3 is used. The random vibration light has a waveform formed so as not to have periodicity, and the action of causing photosynthesis is lower than that of the periodic vibration light.

[0060] Furthermore, the plant growth control method of the present embodiment induces light stress in the cells of photosynthetic plants by irradiating random vibration light. In addition, the plant growth control method of the present embodiment promotes the conversion of carbohydrates, which are photosynthetic products, into antioxidants, and suppresses the growth process of photosynthetic plants. And in the plant growth control method of the present embodiment, the control of the growth process of photosynthetic plants is at least any one of suppression of weight increase of photosynthetic plants, suppression of flowering, and increased production of specific metabolites.

[0061] <Plant cultivation device (photosynthetic plant growth control device) 10> FIG. 9 shows a schematic configuration of the plant cultivation device (photosynthetic plant growth control device) 10 according to the present embodiment. The plant cultivation device 10 includes a cultivation bed 12 for hydroponics or soil cultivation, a light irradiation unit 14 that irradiates light toward the cultivation bed 12, and an irradiation light control unit 16 that drives the light irradiation unit 14 to light up. The plant cultivation device 10 has a protection member 18 that covers the cultivation bed 12 to form a cultivation chamber. It is also possible to omit the protection member 18.

[0062] The light irradiation unit 14 includes a main light source 20 that irradiates main light and an additional light source 22 that irradiates additional light. The main light source 20 and the additional light source 22 are individually driven and controlled by the control (here, current control) of the irradiation light control unit 16. In FIG. 9, the main light source 20 and the additional light source 22 are shown side by side horizontally, but the light of the main light source 20 and the light of the additional light source 22 are irradiated toward the cultivation bed 12 through a diffusion plate (which may be a diffusion lens, not shown in the figure) via the same path. The light of the additional light source 22 may be irradiated toward the cultivation bed 12 through an optical fiber (not shown in the figure). As the optical fiber, one that emits light from the end face or the side face can be appropriately used.

[0063] The main light source 20 continuously lights up within a predetermined time and continuously emits main light (also referred to as "continuous irradiation light"). As the main light source 20, for example, artificial light sources such as LEDs, fluorescent lamps, plasma lamps, mercury lamps, incandescent bulbs, metal halide lamps, sodium lamps, or electrodeless lamps, pulsed oscillation lasers, etc. are used.

[0064] As another main light, it is also possible to use sunlight. When using sunlight, it is possible not to use the main light source 20 or to omit the main light source 20. It is also possible to use sunlight and the light of the main light source 20 in combination. In this case, the sunlight and the light of the main light source 20 may be used separately according to conditions such as time zones. Furthermore, the sunlight and the light of the main light source 20 may be emitted simultaneously.

[0065] The additional light source 22 includes an additional signal light source 24 and an additional relaxation light source 26. The additional signal light source 24 is capable of irradiating additional signal light. The additional signal light source 24 in the present embodiment can selectively or simultaneously irradiate random vibration light and periodic vibration light as the additional signal light. The additional relaxation light source 26 is capable of irradiating additional relaxation light. Only the additional signal light (only random vibration light, only periodic vibration light, or only the light synthesized from random vibration light and periodic vibration light), or the combination of the additional signal light and the additional relaxation light constitutes the additional light. In the present embodiment, flowering adjustment is performed only by the irradiation of the additional signal light source 24. However, as in the example of FIG. 9, an additional relaxation light source 26 may be added to enable the irradiation of additional relaxation light. For this reason, hereinafter, not only the configuration related to the additional signal light source 24 but also the configuration related to the additional relaxation light source 26 will be described. In the experiments of the inventors, for plants in which good growth was not observed with respect to growth adjustment only by the irradiation of additional signal light (here, regular vibration light), subsequent irradiation of additional relaxation light improved the growth status of the plants.

[0066] In FIG. 9, the additional signal light source 24 and the additional relaxation light source 26 are shown side by side. However, the additional signal light and the additional relaxation light are irradiated toward the cultivation bed 12 through a diffusion plate (which may be a diffusion lens) whose illustration is omitted, along the same path. The additional light source 22 may be an integrated unit that integrates the additional signal light source 24 and the additional relaxation light source 26.

[0067] The additional light source 22 can emit light in the wavelength range of 220 nm to 2000 nm by the additional signal light source 24. For the additional signal light source 24, various light sources such as LEDs, ELs (electroluminescence), lasers, ultraviolet light, and infrared light can be adopted as long as they can emit light with a wavelength suitable for the growth of the plants to be cultivated. Also, it is desirable to use a light source for the additional signal light source 24 that is easy to control for pulse lighting. As the additional relaxation light source 26, for example, various light sources such as cold cathode fluorescent lamps driven by electric lamp lines (50 Hz or 60 Hz), LED single-color lamps, and LED fluorescent lamps can be adopted.

[0068] Although illustration is omitted, the additional light source 22 may be a continuously emitting light source and may include a shutter disposed in the optical path. In this case, the optical path is intermittently blocked by the shutter to form signal light (random vibration light and / or periodic vibration light). Further, it is also possible to attach a wavelength limiting filter to the white light source to form light of a required wavelength. The shutter and the filter may be provided for each of the additional signal light source 24 and the additional relaxation light source 26.

[0069] The light irradiation unit 14 is installed above the ceiling surface or side wall of the protection member 18, or above a pillar installed on the cultivation floor 12. The light irradiation unit 14 illuminates the cultivation floor 12 in accordance with a command from the irradiation light control unit 16.

[0070] The light irradiation unit 14 can be configured to include a plurality of main light sources 20 and a plurality of additional light sources 22, respectively. In this case, the plurality of main light sources 20 and the plurality of additional light sources 22 can be arranged at different positions and with different irradiation angles. For example, it is also possible to arrange the plurality of main light sources 20 and the plurality of additional light sources 22 alternately. Further, it is also possible to include a plurality of main light sources 20 and a single additional light source 22 (or a single main light source 20 and a plurality of additional light sources 22). It is also possible to install the additional light source 22 so that light is irradiated onto the cultivation floor 12 from a plurality of directions. By doing so, a more stable growth adjustment effect can be obtained.

[0071] In this way, by providing a plurality of main light sources 20 and / or a plurality of additional light sources 22, it becomes possible to perform more precise light irradiation. And by varying the arrangement and irradiation angles of the plurality of light sources, the plants on the cultivation floor 12 can be uniformly irradiated with light, and growth unevenness due to location can be suppressed.

[0072] The irradiation light control unit 16 drives the light irradiation unit 14 to light up based on the plant cultivation method of the present embodiment. The irradiation light control unit 16 can drive only the main light source 20 to light up, drive only the additional light source 22 to light up, or drive both the main light source 20 and the additional light source 22 to light up simultaneously.

[0073] When the light irradiation unit 14 includes a plurality of main light sources 20 and / or a plurality of additional light sources 22, the irradiation light control unit 16 can synchronize and light up the light sources of the same type. Also, when the cultivation floor 12 is divided into a plurality of blocks (test plots), the irradiation light control unit 16 can individually control the main light source 20 and the additional light source 22 in each block.

[0074] The irradiation light control unit 16 may synchronize the main light source 20 and the additional light source 22 in units of blocks, or may synchronize the main light source 20 and the additional light source 22 of a plurality of blocks or all blocks. By synchronizing the additional signal light (here, periodic vibration light) in the additional light source 22, the duty ratio (duty) of the additional signal light irradiated on the plant can be accurately maintained.

[0075] Such a plant cultivation device 10 can be widely applied to small cultivation kits for easy indoor cultivation in ordinary households, large-scale ones such as agricultural greenhouses, and plant factories having constructed cultivation rooms.

[0076] Here, the agricultural greenhouse refers to not only an agricultural vinyl greenhouse in which a film having light transmissivity is extended over the entire surface of the greenhouse, but also an agricultural glass greenhouse in which a film is stretched and extended over the entire inner surface of the glass window. In the agricultural glass greenhouse, the air containing moisture in the cultivation space inside the greenhouse passes through the film and exits the greenhouse through the gap between the glass window and the framework part of the glass window. Therefore, even in the agricultural glass greenhouse, it is possible to suppress the inside of the greenhouse from becoming hot and humid. Note that the above-mentioned "light transmissivity" means the property of passing the light necessary for growing plants during the day.

[0077] When an additional light source (here, the additional light source 22) is installed inside an agricultural greenhouse, part of the additional light is reflected and diffused (reflection and diffusion) by a glass plate, a resin plate, a resin film, etc., so there is an advantage that the irradiation efficiency of the additional light is improved. The same effect of improving the irradiation efficiency can also be obtained in a small cultivation kit, a plant factory, etc.

[0078] Also, the effective irradiation direction of the additional light (additional signal light and / or additional relaxation light) can be considered. Whether the additional light is irradiated from the same direction as the main light or from a different direction from the main light, a growth promotion effect can be obtained in both cases. Furthermore, if the additional light is irradiated to a place where the main light does not reach sufficiently (for example, the front and back leaf surfaces of the leaves located in the shade, or the back surface of the leaves in the sunny place), a greater growth promotion effect can be obtained.

[0079] Specifically, for example, for a plant whose branches extend in the horizontal direction like a grape, the additional light is irradiated upward from the ground (including the obliquely upward direction). In this case, the light hitting the back surface (the surface on the ground side) of the leaves in the shade increases. And compared with the case where the additional light is not irradiated, photosynthesis is actively carried out and the sweetness of the grapes increases. Thus, by setting the irradiation direction of the additional light according to the environment in which the plant is cultivated, the characteristics of the plant, etc., the growth of the plant can be promoted more effectively. For example, in tomato cultivation, it is also effective to install a side-emitting optical fiber in the foliage and irradiate the additional light.

[0080] <Generation of the waveform of the random vibration light> As shown in FIG. 2, the random vibration light according to this embodiment has a fixed lighting time for each cycle (each lighting time), but the non-lighting time between each cycle changes randomly. The generation procedure thereof is described below. In this embodiment, the lighting time for each cycle is fixed to a constant value.

[0081] The random vibration light according to this embodiment can be generated, for example, by a waveform generation method having the following steps. Further, the following waveform generation method can be performed using a CPU, ROM, RAM, communication I / O, etc. of a computer device and a computer program developed in the RAM and executed by the CPU, although illustration is omitted.

[0082] <<Step 1>> As shown in FIG. 14, a 15-bit random number sequence is generated using the rand() function.

[0083] <<Step 2>> An 8-bit number sequence is extracted from the 15-bit random number sequence (from 0 to 255), and the extracted sequence is rearranged as shown from the left term to the right term below to form a random number sequence. "0" "1" "2" ··· "254" "255" → "152" "8" "22" ··· "344" "249" Each value of the random number sequence becomes the non-illumination time (μs) of the random vibration light.

[0084] <<Step 3>> The random numerical sequence obtained in <<Step 2>> is substituted into the PWM (pulse width modulation) function to generate a random pulse signal in an electric circuit (random vibration light generator). The electric circuit (random vibration light generator) may be provided, for example, in the irradiation light control unit 16 shown in FIG. 9, or may be provided separately from the irradiation light control unit 16.

[0085] <<Step 4>> The procedures from <<Step 1>> to <<Step 3>> are executed for each block (FIG. 3). As shown in FIG. 3, the irradiation of the random vibration light is performed for each of a plurality of blocks arranged in time series. In FIG. 3, the first block at the left end is connected to the second block and subsequent blocks to the right. "N" in the Nth block at the right end in FIG. 3 indicates a natural number of 1 or more.

[0086] For each block, for example, generation of a signal sequence as shown in FIG. 2 is performed. In the present embodiment, the time of each block is determined by the clock frequency of the CPU used. In the present embodiment, the time of each block is 300 μs.

[0087] By executing each such step for each block as shown in FIG. 3, a random (irregular) waveform can be generated without repeating the same signal sequence. Then, by reflecting the information of the generated waveform in the intensity of the additional signal light, random vibration light is output.

[0088] <Other waveform generation methods> The waveform generation method as described above is an example, and it is also possible to generate the waveform of random vibration light by other methods. For example, the waveform generation method as described above is a method using pseudo-random numbers generated by a computer device. Therefore, it can be said that the random vibration light by the above-described waveform generation method (hereinafter referred to as "waveform generation method 1") is a "pseudo-random signal".

[0089] On the other hand, a method (waveform generation method 2) for generating vibration light that is as random as possible can be considered. And, in order to generate such random vibration light, it is possible to utilize dielectric barrier discharge.

[0090] In dielectric barrier discharge, for example, an AC voltage is applied to a pair of dielectric electrodes placed in a rare gas atmosphere using a light-emitting device as shown in FIG. 15(a) to generate a rare gas discharge. When the insulation property related to the surface of the dielectric electrode (the dielectric property of the surface of the dielectric electrode) is non-uniform, the discharge timing of the rare gas also varies and becomes non-uniform (irregular). By exciting the phosphor with such irregular discharge, random vibration light can be obtained. FIG. 15(b) is an example of a time spectrum related to random vibration light generated by the dielectric barrier discharge method.

[0091] By using the randomly vibrating light generated in this way, it is also possible to suppress the growth process of plants and to promote the production of specific metabolites due to light stress.

[0092] As an example of a method for creating an electrode with non-uniform dielectric properties (charging properties), for example, a method performed in the following procedure can be cited. Step 1: A dielectric is thick-film coated on a metal plate to form a discharge electrode. Step 2: The discharge electrode is fired at a high temperature. Step 3: Non-uniform unevenness is formed on the surface of the fired dielectric thick film by, for example, sandblasting or polishing using sandpaper.

[0093] In this way, it is possible to form a dielectric surface with random variations in charging properties. Then, the discharge start voltage at each location on the electrode surface becomes random, and randomly vibrating light can be generated.

[0094] <Applications of this Embodiment> Note that this embodiment merely shows an example of the implementation of the present invention, and the technical scope of the present invention should not be construed in a limited manner by this. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

[0095] The plant cultivation method (plant growth control method) according to this embodiment is effective for the growth regulation of various types of plants. Therefore, it can be applied to the growth promotion of leafy vegetables, root vegetables, flowers, fruit trees, seaweeds, algae, and microalgae. Furthermore, it is effective for plant cultivation in fields, greenhouses, plant factories, smart cells (smart cell industry, substance production by organisms), land-based aquaculture, the sea surface, the sea, the water surface, underwater, and mountainous areas.

[0096] In addition, the plant cultivation method according to the present embodiment can be applied to both the suppression of flowering in short-day plants and the promotion of flowering in long-day plants. Furthermore, the present embodiment can also be applied to the promotion of growth in neutral plants. Representative short-day plants include, for example, clover, watercress, ginger, mizuna, perilla, chrysanthemum, morning glory, and onamotomi. Representative long-day plants include, for example, iris, radish, spinach, rice, wheat, corn, soybean, tomato, watermelon, pumpkin, sweet potato, cabbage, and Chinese cabbage. Representative neutral plants include, for example, strawberry, spinach, lettuce, taro, tomato, cucumber, and pea.

[0097] <Effects of plants by usage> The additional light has the effects of suppressing photosynthesis and promoting the transfer of products (photosynthetic products) by photosynthesis to the primary metabolic pathway (primary metabolic circuit, pathway for primary metabolism) and the secondary metabolic pathway (secondary metabolic circuit, pathway for secondary metabolism).

[0098] Plants are often used as food, medicine, fragrance components, etc. According to the various photosynthetic biomanufacturing methods described so far, in addition to main light such as sunlight, by irradiating additional light, it is possible to increase the production of food, specific medicinal components, fragrance components, etc.

[0099] For example, generally, the taste of vegetables such as lettuce has a bitterness that children dislike. In the experiments of the inventors, when additional signal light with a wavelength of 500 nm to 600 nm or more was irradiated, the bitterness of lettuce could be suppressed to the extent that it was not felt. This is presumably because the nitrogen components contained in the vegetables were converted into amino acids, glutamic acid, etc. From this, it is possible to reduce the number of consumers who dislike vegetables and expand the consumption volume of vegetables.

[0100] The same is true for pak choi. Japanese domestic pak choi is sometimes evaluated as having a stronger taste stimulus compared to those produced in Thailand and others. However, by irradiating additional light, the stimulus can be suppressed and consumers and consumption volume can be expanded. As described above, irradiating additional light increases the sweetness of grapes. In the experiments of the inventors and others, the sweetness of grapes can also be increased more significantly by irradiating additional signal light with a wavelength of 500 nm to 600 nm or more.

[0101] Based on these findings, it is considered possible to increase, for example, the aroma and sweetness of green tea by irradiating additional light.

[0102] Seedlings irradiated with additional light during at least a part of the seedling raising period (seedlings grown in an additional light environment during the seedling raising period) maintain the promoting effect on growth and metabolite production compared to seedlings not irradiated with additional light thereafter. This is the same whether cultivation is carried out only with main light such as sunlight or white LED light after irradiating additional light, or when both main light and additional light are irradiated. For example, by irradiating additional light a few days before the harvest period and simply completing the irradiation, it is possible to harvest vegetables with few thorns and fruits with strong sweetness at a later date.

[0103] In addition, additional light also has the effect of increasing the germination rate and good product rate of seeds. When plants are grown in an additional light environment from germination to seedling raising, the promoting effect on growth and metabolite production persists compared to when additional light is not irradiated thereafter. This is the same whether cultivation is carried out only with main light after irradiating additional light, or when both main light and additional light are irradiated.

[0104] Additional signal light can control the production of the weight of seeds of rice, wheat, and barley, umami components such as glutamic acid, medicinal components such as β - glucan, and pungent and aroma components of herbs such as herbs and pak choi.

[0105] Therefore, according to the various photosynthetic biomanufacturing methods described so far, seedlings such as lettuce, tomato, and rice with a faster growth rate than before, fruits such as grapes and peaches with a high sugar content, herbs with many medicinal components, herbs with reduced pungency, herbs with many aroma components, and knotweed and shiso containing many pigment components can be cultivated as annual herbs (annual plants). For example, in the case of perilla (such as red perilla), specific metabolic components such as anthocyanin and rosmarinic acid increase.

[0106] To selectively increase the production of secondary metabolites such as ascorbic acid (vitamin C), β-carotene (a precursor of vitamin A), polyphenols, and s-allylcysteine contained in plants, selective excitation of the photoreceptor protein phytochrome may be performed.

[0107] Phytochrome has two types, Pr type and Pfr type, depending on the aggregated form of the protein. The Pr type transitions to the Pfr type by photoexcitation. Conversely, the Pfr type transitions to the Pr type by photoexcitation.

[0108] Among the secondary metabolites, Pr-type phytochrome has an effect of particularly promoting the production of ascorbic acid. On the other hand, Pfr-type phytochrome has an effect of promoting the production of polyphenols, β-carotene, and s-allylcysteine, which is a medicinal component of garlic, which are secondary metabolites other than ascorbic acid. Utilizing these properties makes it possible to control the production of secondary metabolites while suppressing growth.

[0109] In addition to phytochrome, photoreceptor proteins contained in photosynthetic organisms such as plants include phototropin involved in the movement of photosynthetic chlorophyll, phototropism, and stomatal opening and closing, and cryptochrome involved in flowering time and shade avoidance response. By selectively exciting these photoreceptor proteins with additional signal light, further precise control of the growth rate and secondary metabolite production is possible.

[0110] Furthermore, regarding flowering regulation, if the wavelength of the additional signal light is in the visible range (380 nm to 750 nm), the flowering regulation function (flowering regulation function) can be obtained. This is because when the additional signal light (periodic vibration light) irradiates the plant, the mechanism described above causes sunlight perception to occur and the effective sunlight duration for the plant becomes longer.

[0111] In plants, photoreceptor proteins such as cryptochrome, phytochrome, and phototropin are distributed. Cryptochrome and phytochrome are involved in flower bud formation. As shown in FIG. 13, cryptochrome is known to promote flower bud formation by absorbing light with a wavelength of 400 nm to 500 nm. Phytochrome has two types, Pr type and Pfr type, as described above. When mainly absorbing light with a wavelength of 600 nm to 700 nm and light up to 800 nm, a conformational change occurs between the Pr type and the Pfr type. Pr-type phytochrome promotes flower bud formation, and Pfr-type phytochrome inhibits flower bud formation. Phototropin is involved in phototropism, stomatal opening and closing, and chloroplast movement by absorbing light with a wavelength of 400 nm to 500 nm.

[0112] As already described, this embodiment performs specific metabolism of carbohydrates, promotes conversion, retards growth, and thus delays flowering (for any of short-day plants, long-day plants, and neutral plants) by irradiating additional signal light (random vibration light). According to this embodiment, even when the wavelength of the additional signal light overlaps with the absorption wavelength band of cryptochrome or phytochrome, the flowering inhibitory effect on short-day plants is obtained.

[0113] The above shows that the flower bud formation inhibitory effect by the additional signal light exceeds the flower bud formation promoting effect of the photoreceptor protein. That is, it can be said that in flower bud formation, the sunlight duration is more important than the physiological reaction of the photoreceptor protein.

[0114] Thus, the additional signal light can obtain the growth inhibitory effect by irradiating immediately after sunset or by continuously or intermittently irradiating for a certain period during the dark period.

[0115] <Examples of Various Methods for Controlling Plant Growth> Hereinafter, embodiments of the present invention will be described in detail by way of examples. However, the present invention is not limited by the following description.

[0116] <Example 1> Figure 10 shows Example 1 regarding the growth inhibition effect. Figure 10 shows the measurement results of the cell density ratio, total sugar weight ratio, and total ascorbic acid weight ratio in the control (CNT) irradiated with only the main light and the test plot (Test Plot 1) irradiated with the main light and random vibration light.

[0117] Regarding the main light, in both the control (CNT) and the test plot (Test Plot 1), the wavelength is 400 - 750 [μs], and the PPFD is 200 [μmolCO 2 m -2 s -1 . For the random vibration light in the test plot (Test Plot 1), the wavelength is 430 - 600 [μs], and the PPFD is 0.005 [μmolCO 2 m -2 s -1 .

[0118] The object of cultivation (growth control) in this example is Euglena. The culture period is 10 days, and the water temperature during that period is 300K (about 27°C). Furthermore, the main light is the light of a fluorescent lamp, and the irradiation time per day for the main light is from 8:00 to 22:00 (14 hours). Also, the irradiation time per day for the random vibration light is from 0:00 to 24:00 (24 hours).

[0119] As shown in Figure 10, when the cell density ratio, total sugar weight ratio, and total ascorbic acid weight ratio in the control (CNT) are set to 1.0, in the test plot, the cell density ratio is 0.7 ± 0.1, the total sugar weight ratio is 0.6 ± 0.1, and the total ascorbic acid weight ratio is 1.6 ± 0.1.

[0120] According to Example 1, by adding and irradiating random vibration light to Euglena, it was possible to suppress the increase in cell density and increase ascorbic acid, which is an antioxidant.

[0121] <Example 2> Figure 11 shows Example 2 regarding the growth inhibition effect. In Experimental Example 2, Test Plot 1 with only periodically fluctuating light added and Test Plot 2 with both periodically fluctuating light and randomly vibrating light added were compared with the control (CNT) irradiated with only the main light. Figure 11 shows the measurement results of the cell density ratio, total sugar weight ratio, and total ascorbic acid weight ratio in the control (CNT), Test Plot 1, and Test Plot 2.

[0122] Regarding the main light, for all of the control (CNT), Test Plot 1, and Test Plot 2, the wavelength is 400 - 750 [μs], and the PPFD is 200 [μmolCO 2 m -2 s -1 . Regarding the periodically fluctuating light (periodically vibrating light), for both Test Plot 1 and Test Plot 2, the wavelength is 430 - 600 [μs], and the PPFD is 0.015 [μmolCO 2 m -2 s -1 . Regarding the randomly vibrating light in Test Plot 2, the wavelength is 430 - 750 [μs], and the PPFD is 0.005 [μmolCO 2 m -2 s -1 .

[0123] The object of cultivation (growth control) in this example is Chlorella. The cultivation period is 10 days, and the water temperature during that period is 300K (about 23°C). Furthermore, the main light is the light of a fluorescent lamp, and the irradiation time per day for the main light is from 8:00 to 22:00 (14 hours). Also, the irradiation time per day for the randomly vibrating light is from 0:00 to 24:00 (24 hours). Regarding the periodically vibrating light as well, similar to the randomly vibrating light, the irradiation time per day is from 0:00 to 24:00 (24 hours).

[0124] As shown in Fig. 11, when the cell density ratio, total sugar weight ratio, and total ascorbic acid weight ratio in the control (CNT) are set to 1, in Test Group 1, the cell density ratio was 1.4 ± 0.1, the total sugar weight ratio was 1.1 ± 0.1, and the total ascorbic acid weight ratio was 1.1 ± 0.1. In Test Group 2, the cell density ratio was 0.8 ± 0.1, the total sugar weight ratio was 0.7 ± 0.1, and the total ascorbic acid weight ratio was 1.6 ± 0.1.

[0125] According to this Example 2, by adding and irradiating random vibration light to Chlorella, an increase in cell density can be suppressed, and ascorbic acid, an antioxidant, can be increased.

[0126] <Example 3> Fig. 12 shows Example 3 regarding the growth inhibition effect. Fig. 12 shows the measurement results of the total fresh leaf weight ratio, total ascorbic acid weight ratio, and flowering rate ratio in the control (CNT) irradiated with only the main light and the test group (Test Group 1) irradiated with the main light and random vibration light.

[0127] The main light is sunlight for both the control (CNT) and the test group (Test Group 1). Regarding the random vibration light in the test group (Test Group 1), the wavelength is 400 - 750 μm, and the PPFD is 0.005 [μmolCO 2 m -2 s -1 .

[0128] The object of cultivation (growth control) in this example is Polygonum hydropiper. Transplanting was carried out on September 1st, and harvesting was carried out on November 30th. Furthermore, the irradiation time per day for the random vibration light was set to 0 - 24 hours (24 hours).

[0129] As shown in Fig. 12, when the total fresh leaf weight ratio, total ascorbic acid weight ratio, and flowering rate ratio in the control (CNT) are set to 1.0, in the test group, the total fresh leaf weight ratio was 0.7 ± 0.1, the total ascorbic acid weight ratio was 1.7 ± 0.1, and the flowering rate ratio was less than 0.02 (<0.02).

[0130] According to this Example 3, by adding and irradiating random vibration light to Persicaria tinctoria, an increase in fresh leaf weight can be suppressed, and an increase in antioxidant substances and flowering suppression can be achieved.

[0131] <Inventions Extractable from Embodiments and Examples> (1) Irradiation of main light (such as sunlight, artificial light, etc.), which is light stronger than the light compensation point for photosynthesis of the photosynthetic plant to be cultivated, and irradiation of additional signal light (such as only random vibration light, a combination of random vibration light and periodic vibration light, etc.) whose light intensity is lower than that of the main light and weaker than the light compensation point, and whose light intensity varies temporally, and the irradiation of the additional signal light is performed simultaneously with the main light or during a time period when the main light is not irradiated, A method for controlling the growth of a photosynthetic plant, wherein the additional signal light has a waveform formed so as not to have periodicity, and is random vibration light having a lower photosynthesis-inducing effect compared to additional signal light having periodicity (such as periodic vibration light). (2) The method for controlling the growth of a photosynthetic plant according to (1) above, wherein the irradiation of the random vibration light induces photo-stress in the cells of the photosynthetic plant. (3) The method for controlling the growth of a photosynthetic plant according to (2) above, wherein the irradiation of the random vibration light promotes the conversion of carbohydrates, which are photosynthetic products, into antioxidant substances and suppresses the growth process of the photosynthetic plant. (4) The method for controlling the growth of a photosynthetic plant according to (3) above, wherein the control of the growth process of the photosynthetic plant is at least one of suppression of weight increase of the photosynthetic plant, suppression of flowering, and increased production of specific metabolites. (5) The method for controlling the growth of a photosynthetic plant according to any one of (1) to (4) above, wherein the irradiation of the random vibration light is performed by continuously connecting blocks at predetermined time intervals. (6) A device for controlling the growth of a photosynthetic plant, which irradiates main light (such as sunlight, artificial light, etc.) for photosynthesis of the photosynthetic plant to be cultivated, an additional light source that irradiates additional signal light (such as only random vibration light, a combination of random vibration light and periodic vibration light, etc.) in addition to the main light, An irradiation light control unit capable of driving and controlling the additional light source, The light intensity of the additional signal light is relatively smaller than that of the main light and the light compensation point of the photosynthetic plant, and varies temporally, The additional signal light has a waveform formed so as not to have periodicity, and the action of causing photosynthesis is random vibration light with a lower photosynthesis-causing effect compared to additional signal light with periodicity (such as periodic vibration light), A photosynthetic plant growth control device that irradiates the random vibration light to adjust the growth of the photosynthetic plant. (7) The photosynthetic plant growth control device according to (6) above, comprising a main light source that irradiates the main light.

Industrial Applicability

[0132] The photosynthetic plant growth control method and the photosynthetic plant growth control device of the present invention are effective for open-field cultivation, greenhouse cultivation, plant factory cultivation, etc.

Explanation of Signs

[0133] 10: Photosynthetic plant growth control device 12: Cultivation bed 14: Light irradiation unit 16: Irradiation light control unit 18: Protection member 20: Main light source 22: Additional light source 24: Additional signal light source 26: Additional relaxation light source

Claims

1. Irradiation of the main light, which is stronger than the light compensation point, for photosynthesis of the photosynthetic plant to be cultivated; Irradiating the optical fiber with an additional signal light having a light intensity smaller than that of the main light and weaker than the optical compensation point, the light intensity of which varies with time; The additional signal light is irradiated simultaneously with the main light or during a time period when the main light is not irradiated, A method for controlling photosynthetic plant growth, wherein the additional signal light has a waveform formed to have no periodicity, and is random vibration light having a lower effect of inducing photosynthesis than additional signal light having periodicity.

2. 2. The method for regulating the growth of a photosynthetic plant according to claim 1, wherein light stress is induced in cells of the photosynthetic plant by irradiation with the random vibration light.

3. 3. The method for controlling the growth of photosynthetic plants according to claim 2, wherein the irradiation with the random vibration light promotes conversion of carbohydrates, which are products of photosynthesis, into antioxidant substances, thereby suppressing the growth process of photosynthetic plants.

4. 4. The method for controlling the growth of a photosynthetic plant according to claim 3, characterized in that the control of the growth process of the photosynthetic plant is at least one of suppressing weight gain, suppressing flowering, and increasing production of specific metabolic substances in the photosynthetic plant.

5. 5. The method for controlling the growth of a photosynthetic plant according to claim 1, wherein the irradiation of the random vibration light is performed in succession in blocks of a predetermined time.

6. A photosynthetic plant growth control device that irradiates a main light for photosynthesis of a photosynthetic plant to be cultivated, an additional light source that irradiates additional signal light in addition to the main light; an irradiation light control unit capable of driving and controlling the additional light source; The light intensity of the additional signal light is smaller than the main light and the light compensation point of the photosynthetic plant, and varies with time; the additional signal light is a random vibration light having a waveform formed so as not to have periodicity and having a lower effect of inducing photosynthesis than the additional signal light having periodicity; A photosynthetic plant growth control device that adjusts the growth of the photosynthetic plant by irradiating the random vibration light.

7. The photosynthetic plant growth control device according to claim 6 , further comprising a main light source that irradiates the main light.

Images