JP2014171465A - Plant cultivation method and irradiation device for plant cultivation used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plant cultivation method capable of improving photosynthetic efficiency and an irradiation device for plant cultivation used for the same.SOLUTION: The present invention is a plant cultivation method for growing plants by irradiating with pulse light at a frequency of 100 Hz or more. Preferably, the frequency is between 100 kHz and 50 MHz. In another embodiment, an irradiation device for plant cultivation used for the plant cultivation method includes an artificial light source for irradiating with pulse light at a frequency of 100 Hz or more.

Description

  The present invention relates to a plant cultivation method and a plant cultivation irradiation device used therefor, and more particularly to a plant cultivation method capable of improving photosynthesis efficiency and a plant cultivation irradiation device used therefor.

  Currently, there is a demand for technology for efficiently producing and cultivating safe and high value-added plants. Generally, plants (including algae and cyanobacteria) perform photosynthesis under sunlight irradiation conditions, but the light energy to be irradiated is not efficiently utilized. Sunlight includes all light components such as light components necessary for plant growth and light components not necessary for growth. Use of a light source containing all light components, such as a daylight white light source, as an artificial light source is not preferable from the viewpoint of energy efficiency. In particular, in the case of a cultivation apparatus or a vegetable factory for artificially growing plants using an artificial light source, more efficient irradiation is required.

  For example, conventionally, in order to improve the light utilization efficiency in a photosynthesis device using an artificial light source, the plant cultivation method of Patent Document 1 is known. Patent Document 1 discloses an organically cultivated plant factory comprising a fluorescent lamp and a light emitting diode (LED) of 650 to 660 nm as artificial light sources for plants cultivated on an organic medium.

  In general, the light used for photosynthesis in the sunlight spectrum is only light in a limited narrow region such as 660 nm red light. Further, under natural conditions, since the fluctuation of light intensity is large, productivity by actual photosynthesis tends to be lower than that of continuous light irradiation energy. Further, in the photosynthesis reaction in plants, the amount of photosynthesis does not increase any more at the light intensity above the light saturation point. Therefore, when growing a plant under an artificial light source, it is necessary to stably irradiate light near the light saturation point in order to increase photosynthesis efficiency. Cited Document 1 attempts to improve energy efficiency for photosynthesis by continuously irradiating light of a specific single or limited wavelength region as an artificial light source.

JP 2008-118957 A

  By the way, there are a light reaction and a dark reaction in photosynthesis, and a direct light irradiation is not necessary for a dark reaction utilizing the reducing power obtained by the light reaction. In nature, the light reaction is highly active during the day, and the dark reaction proceeds mainly at night. Even in a plant photosynthesis apparatus using an artificial light source, incident light is not used continuously. For example, the incident light after light is used for photoexcitation in the electron transport system and before the reducing power produced is processed (utilized) in plant cells can be used for the photosynthetic reaction. Can not. Therefore, it is predicted that the photosynthetic efficiency does not decrease even if the light is not used during the period when the light is not used.

  In the present invention, focusing on light reaction speed control (indirect dark reaction speed control) in addition to the light-dark cycle due to the circadian rhythm in nature, we attempted to control the photosynthetic reaction by pulse processing that repeats light and dark.

  The present invention has been made by finding that, as a result of diligent research by the present inventors, it is possible to improve the photosynthetic efficiency by using a pulse light source at a predetermined frequency as an artificial light source.

  An object of the present invention is to provide a plant cultivation method capable of improving photosynthesis efficiency and a plant cultivation irradiation apparatus used therefor.

  In order to achieve the above object, according to one aspect of the present invention, there is provided a plant cultivation method according to the invention, wherein the plant is cultivated by irradiation with pulsed light having a frequency of 100 Hz or more. The frequency is preferably 100 kHz to 50 MHz.

  In another aspect of the present invention, an irradiation apparatus for plant cultivation used in the plant cultivation method includes an artificial light source for irradiating pulsed light having a frequency of 100 Hz or more. An irradiation apparatus for cultivation is provided.

  The artificial light source includes a light emitting diode (LED), a halogen lamp, an incandescent lamp, a fluorescent lamp, an arc lamp, an electrodeless discharge lamp, a low pressure discharge lamp, a cold cathode fluorescent lamp, an external electrode fluorescent lamp, an electroluminescent light, and an HID. Preferably, the light source is at least one selected from a lamp and a light source via a prism or an optical filter.

  ADVANTAGE OF THE INVENTION According to this invention, photosynthesis efficiency can be improved with the cultivation method of a plant, and the irradiation apparatus for cultivation of a plant used therefor.

The graph which shows the emission spectrum of LED light used in Test Example 1.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in a plant cultivation method will be described.
The plant cultivation method of this embodiment is performed by irradiating a plant with a predetermined pulsed light as a light source. For the pulsed light, a frequency of 100 Hz or more, preferably 100 kHz or more, more preferably 200 kHz or more, and further preferably 500 kHz or more is used. As the frequency of the pulsed light increases, the photosynthesis efficiency can be improved. On the other hand, from the viewpoint of easy availability of a light source that emits pulsed light, the pulsed light preferably has a frequency of 50 MHz or less, more preferably 10 MHz or less, and even more preferably 5 MHz or less. Further, when the frequency of the pulsed light exceeds 50 MHz, the photosynthetic efficiency tends to be saturated.

  As the light source, a light source including all light components, for example, a daylight white light source may be used, and light having a single wavelength or a limited wavelength region used for photosynthesis can be used. From the viewpoint of improving energy efficiency, light of a single wavelength or a limited wavelength region used for photosynthesis is preferable. The wavelength used for photosynthesis is appropriately determined depending on the type of plant, the type of photosynthetic pigment that the plant has, the growth stage of the plant, the content ratio of the photosynthetic pigment, and the like. For example, the peak wavelength of photosynthesis in plants generally includes around 450 nm, around 550 nm, and around 660 nm. As a wavelength region including a wavelength near 450 nm, 400 to 500 nm is preferable, and 420 to 480 nm is more preferable. The wavelength region including a wavelength around 550 nm is preferably 500 to 600 nm, and more preferably 520 to 580 nm. The wavelength region including a wavelength near 660 nm is preferably 600 to 700 nm, and more preferably 640 to 680 nm.

  The plant to which the plant cultivation method of the present embodiment is applied is a concept including widely living organisms that carry out photosynthesis, and includes algae and cyanobacteria in addition to land plants. The land plant is not particularly limited, and examples thereof include edible sugar beets and grains, horticultural crops, and ornamental plants (houseplants). Specific examples include plants of the Brassicaceae, Asteraceae, Rabbitaceae, Legumes, Rubiaceae, Eggplants, Cucurbitaceae, and Gramineae.

Next, the effect | action of the cultivation method of the plant comprised as mentioned above is demonstrated.
The plant cultivation method of this embodiment uses pulsed light with a frequency of 100 Hz or more. Thereby, for example, it is possible to improve the photosynthetic efficiency as compared with the case where light having a duty ratio of 100% is irradiated. In general, a photosynthesis reaction performed by a plant includes a photochemical system I and a photochemical system II that require light for the progress of the reaction, and an electron transfer system that connects them. Since these reactions proceed in the order of microseconds, the light synthesis efficiency can be improved by irradiating light necessary for driving the two photosystems with high frequency, for example, kilohertz order and megahertz order pulse light. It is considered a thing.

According to the plant cultivation method of the present embodiment, the following effects can be obtained.
(1) In the plant cultivation method of this embodiment, plants are cultivated by irradiating pulsed light with a frequency of 100 Hz or higher. Therefore, for example, it is possible to improve the photosynthetic efficiency as compared with the case where light with a duty ratio of 100% is irradiated.

(2) Preferably, light having a wavelength in the vicinity of 450 nm, 550 nm, or 660 nm is used as the pulsed light. Therefore, the photosynthetic efficiency can be further improved.
In addition, you may change the said embodiment as follows.

-In the said embodiment, the intensity | strength of irradiated light and the irradiation time of light are suitably set according to the kind of plant, the irradiation objective, the growth stage of a plant, a light source, etc. It is preferable to stably irradiate light in the vicinity of the light saturation point from the viewpoint of increasing photosynthesis efficiency. More specifically, the light irradiated is preferably 0.1~100mW / cm ^2, more preferably 0.5~20mW / cm ^2. Within this range, more efficient photosynthesis is expected.

  In the present embodiment, the duty ratio (duty ratio) is appropriately set according to the type of plant, the purpose of irradiation, the growth stage of the plant, the light source, and the like. For example, the duty ratio (duty ratio) is preferably 20 to 80%, more preferably 40 to 60%, from the viewpoint of improving energy efficiency.

(Second Embodiment)
Hereinafter, the plant cultivation irradiation device for carrying out the plant cultivation method of the first embodiment of the present invention will be described in detail. Hereinafter, the difference from the first embodiment will be mainly described.

  The irradiation apparatus for plant cultivation of this embodiment is an artificial light source for irradiating pulsed light with a frequency of 100 Hz or more, preferably 100 kHz or more, more preferably 200 kHz or more, and further preferably 500 kHz or more from the viewpoint of improving photosynthesis efficiency. Prepare. On the other hand, from the viewpoint of easy availability, the pulsed light of the artificial light source preferably has a frequency of 50 MHz or less, more preferably 10 MHz or less, and even more preferably 5 MHz or less.

  The artificial light source is not particularly limited, but known light sources such as LEDs, halogen lamps, incandescent lamps, fluorescent lamps, arc lamps, electrodeless discharge lamps, low-pressure discharge lamps, cold cathode fluorescent tubes, external electrode fluorescent tubes, electro Luminescent lights and HID lamps can be used. Examples of the HID lamp include a high-pressure mercury lamp, a metal halide lamp, and a high-pressure sodium lamp. The artificial light source includes a light source having a specific wavelength obtained through natural light through a prism or an optical filter in addition to artificially produced light. These artificial light sources may be used alone or in combination of two or more.

  Among these artificial light sources, an LED is preferable from the viewpoint that it is easy to irradiate light of a single wavelength or a narrow wavelength region, and light adjustment by pulse blinking is easy. The shape of the LED is not particularly limited, and examples thereof include a shell type and a surface mount type, and may be either a single chip or a multichip. Moreover, you may employ | adopt high brightness LED as LED. Known configurations can be appropriately adopted as the configuration for holding the artificial light source, for example, the stand and the wiring.

  The place where the irradiation device for plant cultivation is installed is not particularly limited, and it can be installed anywhere where photosynthesis of the plant is necessary. Examples include farms, greenhouses, plant factories, storage facilities, transport vehicles, and display shelves. Examples of the storage facility include a refrigerator, a constant greenhouse, a warehouse, and a container. As a conveyance vehicle, a trolley | bogie, the loading platform of a wagon, and a container cargo are mentioned, for example. Among these, it is preferably applied to a fully artificial light source type plant factory from the viewpoint of requiring highly efficient operation.

The effects exhibited by this embodiment will be described below.
(3) According to the plant cultivation irradiation apparatus of the present embodiment, an artificial light source for irradiating pulsed light having a frequency of 100 Hz or more is provided. Therefore, the photosynthesis efficiency can be improved by such an apparatus.

  (4) In this embodiment, an artificial light source is used as the light source. Therefore, it is possible to easily select and irradiate light in a specific wavelength region. Moreover, the growth of plants can be promoted by more efficient photosynthesis in a controlled environment without being influenced by weather conditions like sunlight.

  (5) According to the plant cultivation irradiation device of the present embodiment, known light sources such as LEDs and halogen lamps can be employed. Therefore, light irradiation can be performed easily and inexpensively.

  (6) As this embodiment, Preferably, LED is used as an artificial light source. An LED can be easily irradiated with light of a single wavelength or a narrow wavelength range, and light control by pulse blinking is easy. Therefore, in the present embodiment, it is possible to easily irradiate pulse light in a specific wavelength region of interest, and it is possible to operate more efficiently in production / growth activities. Moreover, since LED has a long life and low power consumption, it can be implemented at low cost.

  (7) As this embodiment, Preferably, it is provided with at least 1 type chosen from a farm field, a greenhouse, a plant factory, a storage facility, a conveyance vehicle, and a display shelf. The technique for controlling the irradiation apparatus for plant cultivation can be used not only in a plant factory, but also in the agricultural field, food distribution field, and retail field. For example, the application of photosynthesis control technology is expected during cultivation of plants, after harvesting of harvested products, and in maintaining freshness in the distribution process, storage period, and over-the-counter sales period.

  (8) The present embodiment is preferably applied to a fully artificial light source type plant factory. Therefore, it is expected to efficiently produce and cultivate safe and high value-added products for a wide range of plants while controlling the growth environment.

In addition, you may change the said embodiment as follows.
-In the said embodiment, light may be irradiated to a plant directly from an artificial light source, and you may irradiate through an optical apparatus, for example, an optical fiber, a lens, and a reflective mirror. With this configuration, it is possible to employ a configuration in which the light source and the irradiation site are separated. Further, the irradiation light can be easily increased by condensing light or the like. Therefore, plant growth can be promoted by more efficient photosynthesis.

  -As for the irradiation apparatus for cultivation of the plant of the said embodiment, the irradiation site | part which irradiates an artificial light source may be comprised by shelf shape. With such a configuration, since many plants can be irradiated at a time, efficient operation is possible.

-You may comprise the irradiation apparatus for cultivation of the plant of the said embodiment as a movable type by attaching a wheel to the holding means holding an artificial light source.
-The irradiation apparatus for cultivation of the plant of the said embodiment may irradiate continuously to the moving plant by attaching a conveyor under the irradiation part which irradiates an artificial light source. With such a configuration, even a few light sources can efficiently irradiate many plants.

Next, the embodiment will be described more specifically with reference to examples.
(Test Example 1)
The photosynthesis efficiency when irradiating pulsed light to grasses, which are staple foods in Japan, was tested.

(sample)
The cultivar “Yumetsukushi” was used as a gramineous plant. As the CO ₂ concentration measuring device, a CO ₂ recorder TR-76Ui (manufactured by T & D) using an NDIR type sensor was used.

(light source)
An LED light source was used as the light source. As the LED light source, a 3 in 1 type red light source was used. The light irradiation to the rice was adjusted to a distance of 22 cm from the tip of the rice to the light source, and an irradiation experiment was performed by lighting one ball.

  First, the light spectrum, light irradiation intensity, and photon number were measured for the light source used in the test. The measurement was performed under the conditions that one ball was fully lit (duty: 100%) and the distance between the light sources was 22 cm.

  Optical spectrum and light irradiation intensity were measured using an optical fiber spectroscopy system (USB 4000, manufactured by Ocean Optics) and analysis software (SpectraSuit, manufactured by Ocean Optics). The following conditions were adopted as measurement conditions.

Integration Time: 200ms
Average number of times: 1 Integration range: 600 nm to 700 nm
For photon number measurement, an optical quantum meter (LI-250A Light Meter, manufactured by LI-COR) was used as a measuring instrument.

The measurement result of the optical spectrum is shown in FIG. As shown in FIG. 1, it is confirmed that the light source is a single band having a light emission maximum in the vicinity of 660 nm.
The irradiation intensity was 3800 μW / cm ² . The photon number was confirmed to be 149 μmol / s · m ² .

(Method)
Rice (growing for 30 days at room temperature (25 ° C) after sowing) is put into a desiccator equipped with an LED light source, and a CO ₂ standard gas push can is used to induce high CO ₂ concentration in the desiccator. Injected.

In the desiccator, the injected CO ₂ was circulated well and the concentration was stabilized, and then light irradiation with pulsed light was performed on rice. For pulse dimming, conditions of 1 kHz, 10 kHz, 100 kHz, 250 kHz, 500 kHz, and 750 kHz were employed. The duty ratio was 50%. For comparison, continuous light with a duty ratio of 100% was used. Light irradiation was performed for 30 minutes, and then the CO ₂ concentration in the desiccator was measured. From the measured CO ₂ concentration, the CO ₂ concentration absorbed by rice by light irradiation was determined. The results are shown in Table 1. The reproducibility of the experiment was 2 times for 1 kHz, 4 times for 100% duty ratio, and 1 time for others. In the case of 1 kHz and a duty ratio of 100%, an average value ± standard deviation is shown, and the others are measured values.

As shown in Table 1, since absorption of CO ₂ was observed by high-frequency pulse irradiation, it was confirmed that photosynthesis was also activated by pulse irradiation. In the case of a control with a duty ratio of 100%, the amount of CO ₂ absorbed was about 125 ppm. On the other hand, in the case of the pulsed light used in this study was a high CO ₂ absorption amount than half the value of the CO ₂ absorption amount of the 100% duty ratio. In the case of pulse irradiation with a duty ratio of 50%, the irradiation amount or irradiation energy obtained by integrating the irradiation time is considered to be half of continuous light with a duty ratio of 100%. That is, the improvement in photosynthetic efficiency was confirmed in each pulse light used in this test. It was also confirmed that the photosynthetic efficiency improved as the frequency increased. In particular, the irradiation with 750 kHz pulsed light was the same as the amount of CO ₂ absorbed when the duty ratio was 100% even though the irradiation energy was half. From the above, it was suggested that the photosynthesis efficiency can be improved more than the continuous irradiation light by adopting the pulse irradiation light.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(A) The method for cultivating the plant, wherein the plant is Gramineae. Therefore, according to the invention described in (a), the cultivation efficiency of gramineous plants can be further improved.

  (B) The method for cultivating the plant, wherein the pulsed light has a duty ratio of 20 to 80% and an irradiation wavelength of 640 to 680 nm. Therefore, according to the invention described in (b), the photosynthetic efficiency can be further improved.

Claims (4)

  A plant cultivation method comprising cultivating a plant by irradiating pulsed light having a frequency of 100 Hz or more.   The said frequency is 100 kHz-50 MHz, The plant cultivation method of Claim 1 characterized by the above-mentioned. In the irradiation apparatus for cultivation of the plant used for the cultivation method of the plant of Claim 1 or Claim 2,
An irradiation apparatus for cultivation of a plant, comprising an artificial light source for irradiating pulsed light having a frequency of 100 Hz or more.   The artificial light source includes a light emitting diode (LED), a halogen lamp, an incandescent lamp, a fluorescent lamp, an arc lamp, an electrodeless discharge lamp, a low pressure discharge lamp, a cold cathode fluorescent lamp, an external electrode fluorescent lamp, an electroluminescent light, and an HID. The irradiation device for plant cultivation according to claim 3, wherein the irradiation device is at least one selected from a lamp and a light source via a prism or an optical filter.