JP2001054320A - Method for culturing plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved method for culturing plants with the light of a semiconductor light source in a plant culture device, by which the plants having improved high qualities can be cultured, by controlling the inner humidity of the plant culture device. SOLUTION: This method for culturing plants comprises culturing the plants comprises using a semiconductor light source in a plant culture device and irradiating light having a prescribed wavelength. Therein, the plant culture device is formed in an approximately closed system, and the inner relative humidity of the plant culture device is retained at <=60%. Red light having a peak wavelength of 600 to 700 nm is irradiated as the irradiation light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cultivating a plant, and more particularly to a method for cultivating a plant in a plant cultivation apparatus such as a plant factory, a vegetable factory, a seedling raising apparatus, etc. The present invention relates to a plant cultivation method for growing higher quality plants by adjusting humidity in a plant cultivation apparatus.

[0002]

2. Description of the Related Art In plant cultivation using a plant cultivation apparatus such as a plant factory, a vegetable factory, and a seedling raising apparatus, light is emitted by selectively irradiating light of a specific wavelength necessary for growing the plant to efficiently cultivate the plant. Various uses of semiconductor light sources such as diodes and semiconductor lasers have been studied. In such plant cultivation, stem breakage, to prevent lodging, etc., in order to ensure sufficient growth, it is important not to unnecessarily lengthen the plant,
It is considered that it is necessary to irradiate a certain amount of blue light together with red light necessary for photosynthesis. However, for example,
A blue LED has a problem that it is difficult to be applied as a light source of a plant cultivation apparatus because the output of the blue LED is lower than that of a long-wavelength light source such as a red LED, and the lamp cost and the power cost are high.

[0003] The inventors of the present invention have focused on reducing the cost of a semiconductor light source and the power cost in a plant cultivation apparatus, and as a result, have used only a red semiconductor light source having a predetermined peak wavelength, and according to the number of days of cultivation. It has been found that if the irradiation light amount is changed based on the specific relationship, a normal plant type can be maintained and a sufficient growth amount can be secured, and it has been previously proposed as a plant cultivation method (see Japanese Patent Application Laid-Open No. 9-37648). ).

[0004]

In the above-mentioned cultivation, no matter what artificial light source is used, for example, when cultivating leafy vegetables such as lettuce or spinach, the stalks are higher than those in the open field. Has a tendency to grow, that is, the stem has a tendency to lengthen. In addition, these vegetables are said to have weak leaves and soft leaves, and in fact, have poor texture, such as crispy, and are not suitable for cooking because they are easily deformed. I have.

The present invention has been found as a result of various studies on suitable cultivation conditions in cultivation at a specific wavelength of a semiconductor light source, and its object is to cultivate a plant such as a plant factory, a vegetable factory, and a seedling raising apparatus. A method for cultivating a plant with light from a semiconductor light source in an apparatus, wherein the humidity is adjusted in the plant cultivation apparatus to provide an improved method for cultivating a plant with higher quality. It is in.

[0006]

In order to solve the above-mentioned problems, a plant cultivation method of the present invention uses a semiconductor light source in a plant cultivation apparatus and irradiates the plant with light of a predetermined wavelength. Wherein the plant cultivation apparatus is configured in a substantially closed system, and the relative humidity in the plant cultivation apparatus is maintained at 60% or less.

[0007] That is, in the plant cultivation method of the present invention, the humidity in the plant cultivation device can be controlled by configuring the plant cultivation device in a substantially closed system, and the relative humidity in the plant cultivation device is reduced to 60% or less. By keeping the weight, the length of the plant can be suppressed, and the quality such as texture can be improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a plant cultivation method according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of the structure of a plant cultivation apparatus suitable for the plant cultivation method of the present invention. FIG. 2 is a perspective view showing one panel unit of a panel light source in the cultivation apparatus of FIG. 1 from the back side. FIG.
Is a graph showing the effect of humidity on lettuce cultivation, and FIG. 5 is a graph showing the effect of humidity on spinach cultivation.

The plant cultivation method of the present invention is a method for cultivating a plant by using a semiconductor light source and irradiating light of a predetermined wavelength in a plant cultivation apparatus. The plants to which the present invention is applied typically include leaf vegetables such as lettuce and spinach, fruit vegetables such as tomato, and flowers such as pansy, but the present invention is applicable to other plants in general including seedlings. it can.

The plant cultivation apparatus used in the plant cultivation method of the present invention includes various facilities and apparatuses for cultivation such as a so-called plant factory, vegetable factory, and seedling raising apparatus. For example, as shown in FIG. 1, the plant cultivation apparatus includes a plant cultivation board (1) formed in a flat box shape, and a panel light source (2) as a light source arranged to face the plant cultivation board. You.

[0011] As the plant cultivation board (1), a submerged type,
A cultivation board of a hydroponic cultivation system such as an NFT type, a spray hydroponic type, and a submerged equal volume exchange type is exemplified. In cultivation of plants using soil, such as pots and seedlings, a method of watering from above can be adopted, but a bottom watering method is preferable. As a cultivation nutrient solution, a cultivation nutrient solution in which trace components such as iron, manganese, and boron are added to a large amount of components such as nitrogen, phosphoric acid, potassium, calcium, magnesium, and sulfur is used. It can also be cultivated with a fertilizer composition based on Yamazaki prescription.

The panel light source (2) comprises a semiconductor light source such as a light emitting diode or a semiconductor laser. Specifically, as shown in FIG. 1, the panel light source (2) has a plurality of panel units (20) arranged in a plate shape.
Also, each panel unit (20) is, as shown in FIG.
Plate-shaped luminous body (3) on the surface of flat box-shaped support plate (21)
Are arranged in a plurality, and each light-emitting body (3) is configured by, for example, mounting a large number of LED chips as a semiconductor light source on a substrate.

The substrate of the luminous body (3) is a printed board in which a copper foil or a silver foil (2) is laminated on a substrate made of a material having high thermal conductivity such as aluminum or ceramic. The LED chip is sealed in a lens shape with a resin such as an epoxy resin on the substrate in order to prevent deterioration due to humidity.

On the back of the panel unit (20), means for flowing a coolant such as water, or radiating fins and cooling air supply means or cooling gas supply means for removing heat from the LED chips are provided. It may be provided. The panel unit (20) illustrated in FIG. 2 is configured such that cooling water flows through piping (22, 22) provided on a side edge. And a plant cultivation board (1)
It is preferable that the surface of the luminous body (3) facing the luminous body is covered with a transparent resin plate or a glass plate to be subjected to a waterproof and moisture-proof treatment.

Panel light source for the cultivation board (1)
The position of (2) is preferably as short as possible with the plant in order to increase the light use efficiency. For example, the distance between the panel light source (2) and the cultivation surface of the cultivation board (1) is the lettuce just before harvesting. Is set to be about 20 to 40 cm. The panel light source (2) emits very little infrared light and has no obstruction such as leaf burning as compared with conventional light sources such as fluorescent lamps, metal halide lamps, and high-pressure sodium lamps. And the emitted light can be used more effectively. It is desirable that the inside of the plant cultivation apparatus is made of a material that reflects light as much as possible, such as a white plate, so that the light of the semiconductor light source can be more efficiently applied to the plant.

The power supply mechanism of the panel light source (2) is configured so that the light output can be controlled according to the growth of the plant to be cultivated. In order to control the output according to various cultivation environment conditions, it is preferable that the output is automatically controlled by a management computer. In particular, when two or more types of semiconductor light sources having different wavelengths are used, it is preferable that the output is controlled for each semiconductor light source.

When cultivating, for example, lettuce or komatsuna, it is effective to irradiate red light having a peak wavelength of 600 to 700 nm as light emitted by the semiconductor light source as described above. The light amount is 50 to 150 μmol /
m ² · s. When spinach or the like is cultivated, elongation of the petiole can be prevented by irradiating red light having a peak wavelength of 600 to 700 nm and blue light having a peak wavelength of 400 to 500 nm together. The amount of blue light is about 5 to 20% of the total amount of light to be irradiated.

Further, red light having a peak wavelength of 600 to 700 nm and far-red light having a peak wavelength of 700 to 800 nm may be irradiated. When irradiating the above-mentioned far-red light together with red light, it is possible to elongate the plant, increase the volume, for example, in seedling production, by using far-red light only immediately after germination, more It is possible to reduce the length of the seedlings and grow higher quality seedlings. Further, red light, blue light and far-red light having the above-mentioned peak wavelengths may be irradiated together. In addition, it is desirable to irradiate such light continuously for 24 hours in order to shorten the cultivation period,
For long-day plants, such as spinach, which do not aim to flower, a dark period is provided for cultivation under short-day conditions.

In the present invention, the panel light source as described above
(2) That is, since the cultivation is performed using the semiconductor light source and there is no obstruction such as burning of the leaves due to infrared rays, the inside of the plant cultivation apparatus can be maintained at a low humidity. Therefore, in the present invention, the above-described plant cultivation apparatus is configured in a substantially closed system, and the relative humidity in the plant cultivation apparatus is maintained at 60% or less. By such humidity adjustment, unnecessary lengthy can be suppressed and quality can be further improved.

The plant cultivation apparatus may have a cultivation space having a substantially closed structure. In other words, in the apparatus illustrated in the figure, the cultivation space formed on the cultivation board (1) is The structure is not directly open to the outside air. In the above-mentioned humidity adjustment of the cultivation space, when plants are cultivated in a closed space, the humidity rises due to transpiration. Therefore, dehumidification is usually performed using a dehumidifier. When humidification is required, humidification is performed by combining a water heater with a blower, or humidification using an ultrasonic steam generator. In addition,
The humidity in the plant cultivation device is controlled by the computer together with the panel light source (2).

The relative humidity in the plant cultivation apparatus needs to be adjusted to 60% or less. However, in consideration of the above-mentioned effects of transpiration from plants and reduction of dehumidification load, the relative humidity is usually 10 to 10%.
It is adjusted to 60%, preferably 10% or more and less than 50%, more preferably 40% or more and less than 50%.
In particular, in order not to significantly reduce the growth rate of the plant,
It is preferable to set the lower limit of the humidity to 10% or more.

The temperature in the plant cultivation apparatus, that is,
The temperature of the cultivation space is adjusted to, for example, 15 to 30C, preferably 20 to 25C in the case of lettuce and salads.
Further, in the case of spinach, the temperature is adjusted to 10 to 25 ° C, preferably 15 to 20 ° C. In the case of Komatsuna, 10
The temperature is adjusted to 30 ° C, preferably 13 to 20 ° C. In the case of bok choy, 10-30 ° C, preferably 18-25 ° C
Adjust to 15-3 for tomato seedlings or pansy seedlings
The temperature is adjusted to 0 ° C, preferably 18 to 25 ° C. In addition, during cultivation, 100 to promote the growth in the above cultivation space.
0 to 3000 ppm, preferably 1000 to 1500 p
It is desirable to apply carbon dioxide to a concentration of pm.

As described above, according to the plant cultivation method of the present invention, the humidity in the plant cultivation apparatus can be controlled by using a semiconductor light source and configuring the plant cultivation apparatus in a substantially closed system. By keeping the relative humidity in the plant cultivation device at the above specific value, plant growth can be suppressed,
Leafy vegetables can improve the quality of plants, for example, the leaf color is darker and a crisper texture can be obtained. It is considered that this is because, by maintaining the inside of the plant cultivation apparatus at the above specific humidity, the opening of the pores can be suppressed, and the absorption rate of carbon dioxide gas can be limited. Furthermore, according to the plant cultivation method of the present invention, since the plant is cultivated at low humidity as described above, the occurrence of disease can be reduced.

[0024]

EXAMPLE 1 Using four cultivation apparatuses shown in FIG. 1, hydroponic cultivation of lettuce (variety: Red Fire) was performed under different humidity conditions. The cultivation apparatus was configured as a submerged hydroponic cultivation apparatus. As a light source, a panel light source (2) shown in FIG. 2 was used. The panel light source (2) is composed of a 20-cm × 50-cm panel unit (20) in which ten luminous bodies (3) each having 30 LED chips are arranged on a ceramic substrate having a thickness of 7 mm and 300 LED chips are arranged. ), And six panel units (20) were arranged. As the LED chip, a DDH type ultra-high brightness red LED chip having a peak wavelength of 660 nm was used.

In the above-mentioned cultivation apparatus, lettuce seeds were sown on a square sponge having a side of 2 cm, germinated at 20 ° C. under white fluorescent light for 5 days, and then transplanted into the cultivation apparatus with 84 strains. Cultivated for 25 days. During cultivation, EC and pH were appropriately adjusted, and the total amount of the hydroponic solution was changed every seven days. Further, by controlling the power of the panel light source (2), the light amount on the cultivation surface was adjusted to 100 ± 5 μmol / m ² · s, and the light was continuously turned on for 24 hours. Then, the temperature inside the cultivation apparatus after germination was set to 22 ° C., and the humidity was set to 80, 60, respectively.
It was adjusted to 40 and 20%. Note that cooling water was circulated at a flow rate of 1.2 liter / minute behind the light-emitting body (3) in order to prevent a rise in temperature due to heat generation of the LED chip.

The cultivated lettuce was measured for stem length and leaf color value. The leaf color value is obtained by measuring the SPAD value of the fifth leaf from the youngest leaf using a leaf chromaticity meter (Minolta: SPAD-5).
02). The result is a relative humidity of 40%
As shown in Table 1, the stem cultivated at a humidity of 40% or less had a short stem length and a high leaf color value. When the leaves of the harvested lettuce were eaten without washing, the lettuce cultivated at a humidity of 60% or less had a crispy texture and had a good taste. However, since it was soft and thin, it did not have a crispy texture and had a crisp texture.

[0027]

Table 1 Relationship between humidity and lettuce quality (Example 1) Humidity (%) Aboveground fresh weight (g) Stem length (cm) Leaf color (SPAD value) 80 115 ± 10 9.3 ± 1.2 12.9 ± 2.1 60 113 ± 11 9.5 ± 1.1 13.4 ± 1.6 40 107 ± 5 6.2 ± 0.8 17.2 ± 2.0 20 105 ± 6 5.7 ± 0. 7 18.1 ± 1.5 (mean ± standard deviation of all 14 strains)

Example 2: Hydroponic cultivation of lettuce (variety: Red Fire) was carried out with four cultivation apparatuses whose temperature and humidity were controlled. Humidity inside the cultivation equipment is 55, 50, 4 respectively
Cultivation was carried out under the same conditions as in Example 1 except that they were set at 5 and 40%. And it evaluated similarly to Example 1. The results are as shown in Table 2.

[0029]

Table 2 Relationship between humidity and lettuce quality (Example 2) Humidity (%) Aboveground fresh weight (g) Stem length (cm) Leaf color (SPAD value) 55 110 ± 11 7.9 ± 2.2 14.1 ± 1.4 50 107 ± 8 6.4 ± 1.8 16.3 ± 1.4 45 109 ± 5 6.5 ± 1.3 17.6 ± 2.3 40 105 ± 7 6.0 ± 1. 0 16.9 ± 1.6 (mean ± standard deviation of all 14 strains)

For Examples 1 and 2, a humidity of 4
When the values of the stem length and leaf color at 0% are set to 100%, and the relative values at other humidity are calculated, the relative values of the stem length and leaf color with respect to the humidity are as shown in the graph of FIG. As a result, it was found that particularly high-quality vegetables having a short stem length and a high leaf color value at a humidity of 50% or less can be cultivated.

Example 3 Using four cultivation apparatuses shown in FIG. 1, spinach (variety: round grain spinach) was grown under hydroponics under different humidity conditions. The same cultivation apparatus as that in Example 1 was used except that the specifications of the panel light source (2) were different. That is, the panel light source (2) arranges 300 DDH-type ultra-high-brightness red LED chips having a peak wavelength of 660 nm, further arranges 150 blue LED chips having a peak wavelength of 450 nm, and LEDs having different wavelengths. The difference from the first embodiment is that the output is controlled for each chip.

In the above cultivation apparatus, spinach seeds whose outer skin has been removed are sown on a 2 cm square sponge,
After germination at 20 ° C. under white fluorescent light for 3 days, 84 strains were transplanted to the above cultivation apparatus and cultivated for 40 days. During the cultivation, as in Example 1, the total amount of the hydroponic solution was changed every seven days. In addition, the amount of light on the cultivation surface was set to 10 ± 1 μm
ol / m ² · s, the total light amount was adjusted to 100 ± 5 μmol / m ² · s, and the lamp was turned on for 12 hours a day. The temperature in the cultivation apparatus after germination was all set at 20 ° C., and the humidity was adjusted to 80, 60, 40, and 20%, respectively.

The cultivated spinach was measured for stem length and leaf color value in the same manner as in Example 1. The results are based on those grown at 40% relative humidity.
As shown in Table 3, the stem length is short at a humidity of 40% or less,
Leaf color value increased.

[0034]

Table 3 Relationship between humidity and spinach quality (Example 3) Humidity (%) Aboveground fresh weight (g) Stem length (cm) Leaf color (SPAD value) 80 82 ± 12 5.2 ± 1.7 24.1 ± 5.7 60 80 ± 10 4.8 ± 1.9 23.6 ± 5.9 40 78 ± 9 2.7 ± 1.4 27.5 ± 4.8 20 75 ± 9 1.9 ± 1.9. 1 28.4 ± 5.2 (mean ± standard deviation of all 14 strains)

When the leaves of the harvested spinach were eaten without washing, the spinach cultivated at a humidity of 60% or less had a crispy texture and had a good taste, but the spinach cultivated at a humidity of 80%. Had no crispness due to the soft and thin leaves and had a crisp texture. As for the taste, spinach cultivated under any humidity conditions was good without "bitterness" or "red" compared to the conventional open-field cultivation.

Example 4: Spinach (variety: round grain spinach) was hydroponically cultivated using four cultivation apparatuses with controlled temperature and humidity. Cultivation was performed under the same conditions as in Example 3 except that the humidity in the cultivation apparatus was 55, 50, 45, and 40%, respectively. And it evaluated similarly to Example 3. The results are as shown in Table 4.

[0037]

Table 4 Relationship between humidity and spinach quality (Example 4) Humidity (%) Aboveground fresh weight (g) Stem length (cm) Leaf color (SPAD value) 55 87 ± 12 3.5 ± 1.6 23.6 ± 3.6 50 85 ± 9 2.9 ± 1.8 26.3 ± 3.1 45 80 ± 15 1.8 ± 0.9 27.2 ± 2.9 40 83 ± 12 2.2 ± 1. 3 26.9 ± 3.3 (mean ± standard deviation of all 14 strains)

With respect to Examples 3 and 4, Examples 1 and 2
Similarly to the above, when the values of the stem length and leaf color at a humidity of 40% are set to 100% and the relative values at other humidity are calculated, the relative values of the stem length and leaf color for each humidity are shown in FIG.
Is as shown in the graph of FIG. As a result, it was found that, similarly to the case of lettuce, spinach can be cultivated at a humidity of 50% or less, with a short stem length, high leaf color and excellent quality.

[0039]

According to the plant cultivation method of the present invention, the opening of the pores is suppressed by irradiating the semiconductor light source with light of a predetermined wavelength and maintaining the relative humidity in the plant cultivation device at a specific value. In addition, since the absorption rate of carbon dioxide can be restricted, the length of the plant can be suppressed, and the quality of leafy vegetables can be improved, such as a deep leaf color and a crisp texture.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structural example of a plant cultivation apparatus suitable for a plant cultivation method of the present invention.

FIG. 2 is a perspective view showing one panel unit of a panel light source in the cultivation apparatus of FIG. 1 viewed from the rear side.

FIG. 3 is a graph showing the effect of humidity on lettuce cultivation.

FIG. 4 is a graph showing the influence of humidity on spinach cultivation.

[Description of Signs] 1: Cultivation board 2: Panel light source 20: Panel unit 3: Light emitting body

Claims (5)

[Claims] 1. A plant cultivation method for cultivating a plant by using a semiconductor light source and irradiating light of a predetermined wavelength in the plant cultivation device, wherein the plant cultivation device is configured in a substantially closed system, and A method for cultivating a plant, wherein the relative humidity of the plant is maintained at 60% or less. 2. The method for cultivating a plant according to claim 1, wherein red light having a peak wavelength of 600 to 700 nm is irradiated. 3. The plant cultivation method according to claim 1, wherein red light having a peak wavelength of 600 to 700 nm and blue light having a peak wavelength of 400 to 500 nm are irradiated. 4. The plant cultivation method according to claim 1, wherein red light having a peak wavelength of 600 to 700 nm and far-red light having a peak wavelength of 700 to 800 nm are irradiated. 5. The method according to claim 1, wherein red light having a peak wavelength of 600 to 700 nm, blue light having a peak wavelength of 400 to 500 nm, and far-red light having a peak wavelength of 700 to 800 nm are irradiated.