JPH08242694A - Plant cultivation method - Google Patents

Abstract

(57) [Summary] [Objective] To provide a cultivation method in which the light efficiency of a plant is improved at a significantly lower power cost than before. [Structure] Using an optical semiconductor as a light source, a period of 0.5 μsec to 2
A method for cultivating a plant by irradiating with pulsed light in the range of 0 msec and a duty ratio (DT ratio) of 20 to 60%.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a plant factory, a vegetable factory,
The present invention relates to a method for cultivating a plant by pulsed light using an optical semiconductor such as a light emitting diode or a semiconductor laser, for use in a plant cultivation device of a complete artificial light type such as a seedling raising device or a plant cultivation device used in combination with sunlight. .

[0002]

2. Description of the Related Art As long as a plant is cultivated under natural conditions where daily fluctuations are large, fluctuations in yield and harvest time due to environmental fluctuations cannot be avoided. The magnitude of such uncertainties in the production process has been an obstacle to improving the planning of agricultural production and modernizing the working environment. In recent years, as an agricultural environment that is not affected by such changes in natural conditions,
Plant factories, vegetable factories, and nursery equipment that systematically produce crops and seedlings by controlling all conditions that affect plant growth, such as temperature, humidity, carbon dioxide concentration, illuminance, hydroponic solution concentration, and pH in the cultivation environment. Practical application such as is desired. Plant cultivation devices such as plant factories, vegetable factories, and seedling raising devices (hereinafter,
There are two types of plant cultivating equipment), one of which is a complete artificial light type and the other of which is a combination of sunlight. However, both of them have large power costs such as lighting costs and cooling costs, and have not yet been put into practical use. In particular, reduction of lighting cost, which occupies most of electric power cost, is an urgent task for practical application of the plant cultivation device.

For example, regarding the possibility of cultivating a plant using a light emitting diode, "Hort Science, Vol. 26 (2), 203-20"
5, (1991) "and Japanese Patent Laid-Open No. 5-115219. Further, regarding plant cultivation using a semiconductor laser that emits light of 680 nm, the method is disclosed in JP-A-4-12111.
It is proposed in Japanese Patent Publication No. 7. However, although these proposals propose the possibility of cultivating a plant by using an optical semiconductor as a light source, almost no specific conditions for cultivating the plant are shown. In order to actually apply these optical semiconductors to plant cultivation devices such as plant factories, it is necessary to further increase the light utilization efficiency of plants.

It is known that pulsed light has a higher utilization efficiency per unit energy than continuous light as light to be given to plants (Kozosha, "World of Photosynthesis" by Yozo Iwanami). Further, Japanese Patent Publication No. 4-41564 proposes a method of cultivating a plant with a high light intensity by pulsed light using a discharge tube type light source, but this method is at least 7.
The present invention relates to a method that requires an illumination of 5 kilolux, and still requires a large amount of power consumption as lighting for plant cultivation.

[0005]

As described above, the conventional lighting method consumes too much power to be applied to the plant cultivating apparatus of the complete artificial light type or the combined use of sunlight, and produces vegetables and seedlings. Inevitably the price of plants such as
Practical application was difficult. An object of the present invention is to provide an economical method for cultivating a plant using an optical semiconductor as a light source, which solves the above problems.

[0006]

As a result of studies by the present inventors in order to solve such an object, as a result of utilizing the features of optical semiconductors such as light emitting diodes and semiconductor lasers, pulsed light in a specific short cycle range is limited to a certain extent. It was found that by irradiating with a given DT ratio, a plant can be cultivated with an unprecedentedly low electric power. Furthermore, by maintaining the optimum amount of light when pulsed and using only light in the wavelength band that is effective for plants, it has become possible to cultivate plants with significantly reduced lighting power costs.

That is, the gist of the present invention is to use an optical semiconductor as a light source, and a period of 0.5 μsec to 20 msec and a duty ratio (D
(T ratio) A method for cultivating a plant by irradiating with pulsed light in the range of 20 to 60%, and further an average illuminance of 300 Lx
To 5,000 Lx, the cultivation method is characterized by irradiating light, and the wavelength range of the irradiating light is 600 to 750 n.
m of red light alone, or a wavelength range in which red light of 600 to 750 nm and blue light of 400 to 500 nm are used together.

The present invention will be described in detail below. The plant to be the subject of the present invention is not particularly limited, but lettuce, sunny lettuce, lettuce, lettuce such as saladana, cruciferous plants such as komatsuna, Chinese vegetables such as bok choy, tomatoes, etc. It is suitable for plant cultivation.

Examples of the optical semiconductor used as the light source of the present invention include known light emitting diodes (LED) and semiconductor lasers (LD). Examples of the optical semiconductor device that emits red light of 600 to 750 nm include those using Zn—O-doped GaP and GaAlAs-based materials, and examples of the optical semiconductor device that emits blue light of 400 to 500 nm include ZnSSe-based materials. , A material using a GaN-based material has a large optical output and is preferable.

As a specific example of the cultivation apparatus used in the present invention, for example, a light source unit in which light emitting diodes which emit only red light (660 nm) or light of red light and blue light (450 nm) are arranged in a panel form, A completely artificial light type plant cultivation device, which is installed close to the plant cultivation bed, is used. Although many plant species require red light and blue light as light sources, some plant species can grow only with red light, and it is preferable to add the required amount of blue light depending on the species of the plant.

Using such an optical semiconductor, pulsed light having a specific pulse condition, that is, a period of 0.5 μsec to 20 msec and a duty ratio (DT ratio) of 20 to 60%, is preferably used as the average illuminance on the cultivation surface of the plant. 300Lx
To 5000 Lx (for example, DT ratio 50%, pulse period 1 μsec, average illuminance on cultivation surface 1500 Lx), by cultivating by irradiating, plants are clearly more energy efficient than any other light source up to now. It can be cultivated.

The duty ratio (DT ratio) referred to in the present invention is a percentage indicating the ratio between the period T and the light period t, and the DT ratio 100.
% Means continuous irradiation. If the DT ratio is too large or too small, the amount of plant growth decreases, which is not preferable. Irradiation with a pulse cycle of less than 0.5 μsec is also possible in principle, but considering the equipment cost required to blink the high power required for plant lighting in such a short cycle, the production equipment Is not realistic for the purpose of plant cultivation equipment. On the other hand, if the pulse cycle is too large, the growth amount of plants is reduced, which is not preferable.

The average light illuminance on the cultivation surface of the plant is preferably in the range of 300 Lx to 500 Lx, and particularly preferably 500 to 3000 Lx. If the illuminance is too high, the light is saturated and the light utilization efficiency of the plant is lowered. Therefore, the merit of the pulse irradiation is reduced, and if the illuminance is too low, the growth amount of the plant is lowered, which is not preferable.

Specific experimental examples of the contents of the present invention will be shown below, but the contents of the present invention are not limited to the following examples.

Example 1 On a 45 cm x 45 cm acrylic panel as shown in FIG. 1, 1000 cannonball type LED lamps (660 nm at 600 nm, 450 nm at 450 nm)
400 units) were installed, and a power supply device and a pulse generator were connected to grow lettuce (variety: Grand Rapid).

The light period ratio (DT ratio) is 10%, 25
%, 33%, 50%, 100% (that is, continuous light), the pulse period is 1 μsec, and the input power per panel is 4
Adjusted to 0W. Cultivation was performed in a hydroponic device at 22 ° C. and 50% RH, and fresh weights of the above-ground part and the root part were measured after cultivating for 10 days and after cultivating for 20 days.

The results of changes in fresh weight of the aerial part are shown in FIG. 2 and the results of changes in fresh weight of the root part are shown in FIG.
In the practice between -60%, the growth was significantly promoted as compared to unpulsed continuous light and DT ratio of 10%.

Example 2 Using the same apparatus as in Example 1, the DT ratio was fixed at 50%, the pulse period was changed from 1 μsec to 100 msec, and the input power was adjusted to 40 W per panel, and lettuce (variety:
Cultivated Grand Rapid). 22 as in the first embodiment
Cultivation was carried out in a hydroponic apparatus at 50 ° C. and 50% RH, and fresh weights of the above-ground part and the root part were measured after cultivating for 10 days and after cultivating for 20 days.

As a result, as shown in FIGS. 4 and 5, the growth promoting effect was remarkable when the pulse period was pulsed in the range of 1 μsec to 10 msec.

Example 3 On the same acrylic panel as in Example 1, 1000 red light (660 nm) cannonball type LED lamps were installed, a power supply and a pulse generator were connected, and Komatsuna (variety: Tokyo Komatsuna) was cultivated. did. Light period ratio (DT ratio) is 33%, 5
The pulse period was changed to 0% and 100%, the pulse period was adjusted to 1 μsec, and the input power per panel was adjusted to 40W.

Fresh weights of the above-ground part and the root part were measured after cultivating in a pot at 22 ° C. and 50% RH for 20 days and after cultivating for 40 days. As a result, as shown in FIGS. 6 and 7, the growth was significantly promoted as compared with the non-pulsed continuous light.

Example 4 Using the same apparatus as in Example 1, the DT ratio was set to 50% and the cycle was set to 1
The lettuce (cultivar: Grand Rapid) was cultivated by fixing it to μsec and changing the input power to change the average illuminance at the cultivation position of lettuce from 500 Lx to 6000 Lx. As in Example 1, 22 ° C., 50% RH, 20 with a hydroponic device
After cultivating for a day, the fresh weight of the above-ground part and the root part was measured.

As shown in FIGS. 8 and 9, the lettuce grew normally in the range of 500 Lx to 4000 Lx in average illuminance, but the increase in growth at 6000 Lx was greatly suppressed, and the unit under high illuminance was It was found that the light utilization rate of the plant per light quantity was reduced. Therefore, it was effective to irradiate the plants with an average illuminance of 300 Lx to 5000 Lx.

[0024]

By using a new optical device such as an optical semiconductor such as a light emitting diode and irradiating light under a specific pulse condition, it has succeeded in increasing the light utilization efficiency of plants. By using such a plant lighting system, it becomes possible to cultivate a plant at a significantly lower power cost than before, and a light irradiation system and a cultivating method suitable for application to a plant cultivating device such as a plant factory are provided. It is now possible to provide.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a cultivation device used in the present invention.

FIG. 2 is a diagram showing a change in fresh weight of an aerial part in Example 1.

FIG. 3 is a diagram showing a change in fresh weight of a root portion in Example 1.

FIG. 4 is a diagram showing a change in fresh weight of an aerial part in Example 2.

FIG. 5 is a diagram showing a change in fresh weight of a root portion in Example 2.

FIG. 6 is a diagram showing a change in fresh weight of an aerial part in Example 3.

FIG. 7 is a diagram showing a change in fresh weight of a root portion in Example 3.

FIG. 8 is a diagram showing a change in fresh weight of the above-ground portion in Example 4.

FIG. 9 is a view showing a change in fresh weight of a root portion in Example 4.

[Explanation of symbols]

1 ... Acrylic panel, 2 ... Cannonball type LED lamp, 3 ... L
ED panel, 4 ... power controller, 5 ... distributor,

Claims (3)

[Claims] 1. A period of 0.5 μse using an optical semiconductor as a light source.
c to 20 msec, duty ratio (DT ratio) 20 to 6
A method for cultivating a plant by irradiating with pulsed light in the range of 0%. 2. Average illuminance from 300 Lx to 5000 L
The method for cultivating a plant according to claim 1, wherein light irradiation is performed in the range of x. 3. The wavelength range of the irradiation light is 600 to 750 nm.
2. The method for cultivating a plant according to claim 1, wherein the wavelength range is only red light, or a wavelength range in which red light of 600 to 750 nm and blue light of 400 to 500 nm are used together.