JPH0430820B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method and apparatus for keeping agricultural products fresh,
This invention relates to a method for artificially controlling plant growth.

[Conventional technology]

Agricultural products such as vegetables, fruits, flowers, ornamental plants, and bulbs mature by producing ethylene gas during the storage process after being harvested, and ripening can be significantly accelerated in spaces with high concentrations of ethylene gas. It is known (Yoshio Masuda, "Plant Physiology", Baifukan).
Therefore, when storing harvested agricultural products in a closed space, in order to maintain their freshness over a long period of time, it is necessary to remove or suppress the ethylene gas generated from the agricultural products. becomes important. On the other hand, it has been shown in the above-mentioned literature that ethylene gas is also produced during plant growth and that this ethylene gas promotes plant growth. Therefore, when cultivating vegetables, flowering trees, ornamental plants, etc. in a closed space (for example, a greenhouse), controlling the concentration of ethylene gas is important for controlling growth.

Of course, if the harvested produce is placed in an open space with fresh air, some of the ethylene gas generated will be washed away, thereby slowing down the rate at which the produce overheats. However, in cases such as refrigerators, it is impossible to open the storage space for agricultural products, and leaving boxes containing agricultural products open is extremely inconvenient in terms of storage and the like. If some agricultural products rot in such a closed space, the ethylene gas generated therefrom will overheat other agricultural products, and eventually all the agricultural products in the closed space will rot.
The same is true when growing plants in a greenhouse or artificial cultivation room; it is unavoidable for the plant cultivation space to be airtight to a certain extent.

Conventionally, there is a technique disclosed in Japanese Patent Publication No. 55-50451, which maintains the freshness of harvested agricultural products in a closed space. This is an attempt to remove ethylene gas from storage by adsorbing bromine onto carbon having pores of several angstroms. Furthermore, Japanese Patent Application Laid-Open No. 184035/1983 discloses wrapping agricultural products in a freshness-preserving film having ethylene absorption ability.

[Problem to be solved by the invention]

However, the technique disclosed in the former publication requires the use of a large amount of freshness-preserving material even when preserving a small amount of agricultural products, which has the disadvantage of not only being time-consuming but also high in cost. In addition, with the technology disclosed in the latter publication, only a small amount of freshness-preserving film is used to preserve small amounts of agricultural products, so although it has the effect of reducing costs, it requires the additional work of wrapping individual agricultural products in film. This is time-consuming and ends up increasing costs.

On the other hand, if the freshness-preserving material or freshness-preserving film disclosed in the above publication is applied to plant growth control in a greenhouse, a large amount of the material must be used, and when the film is used, Plants would have to be wrapped individually in a film, making practical application to plant growth control impossible.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method and apparatus for maintaining the freshness of harvested agricultural products, which can be easily maintained at low cost in a substantially sealed space.

Another object of the present invention is to provide a method for controlling plant growth that can easily control the growth of plants in a substantially closed space at low cost.

[Means to solve the problem]

As a result of intensive studies to achieve the above object, the present inventors focused on the following two points and came up with the present invention.

First, when a photocatalyst (semiconductor photocatalyst) made of titanium oxide (TiO ₂ ) or platinum (Pt)-supported titanium oxide (semiconductor photocatalyst) is irradiated with light, ethylene gas in an atmosphere containing moisture is decomposed into carbon dioxide. etc. is generated. This is Chemical Physics Letters.
Physics Letters) Vol.70, No.1 (1980, 2, 15)
It has been shown that ethylene gas undergoes a decomposition reaction according to the reaction formula: C ₂ H ₄ +4H ₂ O→2CO ₂ +6H ₂ in the presence of an excited photocatalyst. Here, carbon dioxide produced as a result of the decomposition of ethylene gas is a competitive inhibitor of the action of ethylene, which brings about the ripening of agricultural products, as shown in the above-mentioned literature by Yoshio Masuda, and the carbon dioxide produced as a result of the decomposition of ethylene gas, which brings about the ripening of agricultural products. It is a competitive inhibitor of action. Therefore, by removing ethylene gas, it becomes possible to suppress the ripening of agricultural products and the growth of plants, while at the same time suppressing the above-mentioned effect of ethylene using carbon dioxide.

The second point to note is that conventional freshness preservation materials and freshness preservation films all try to suppress the ripening of agricultural products and the growth of plants by adsorbing or absorbing ethylene gas. It is a mold (absorption type) freshness preservation technology. For this reason, the adsorption capacity of ethylene decreases with the passage of time in conventional products, and therefore they are not suitable for long-term freshness maintenance, and the adsorption material itself must be replaced frequently. Furthermore, it is not possible to control the ethylene adsorption capacity. On the other hand, the photocatalyst is completely different from the ethylene adsorption type, as it decomposes ethylene (ethylene decomposition type), and since the material used is a catalyst, unlike the conventional adsorption type, only a small amount is required; Ethylene resolution does not decrease with use time. Therefore, there is no need to replace materials in principle, and the ethylene decomposition ability can be freely controlled by light irradiation.

The freshness preservation method according to the present invention is a freshness preservation method for preserving the freshness of agricultural products that mature by producing ethylene and whose ripening is promoted by ethylene. The present invention is characterized in that a photocatalyst that decomposes agricultural products is placed in a nearly sealed space containing the above-mentioned agricultural products, and the photocatalyst (semiconductor photocatalyst) is excited by irradiation with light having a band gap energy or higher. Here, the photocatalyst is composed of, for example, a semiconductor catalyst containing titanium oxide or platinum-supported titanium oxide. The ethylene gas is decomposed according to the reaction equation described above under the supply of moisture from the reactor.

The freshness preservation device according to the present invention is a freshness preservation device for maintaining the freshness of agricultural products, which mature by producing ethylene and whose ripening is promoted by ethylene, in a substantially closed space such as a refrigerator. a substantially sealable container forming a produce storage space for storing the produce; and a ventilated holding member disposed on the container so as to form a photocatalyst storage space in contact with the produce storage space; , and a photocatalyst that is disposed in a photocatalyst housing space and that decomposes ethylene by photoexcitation. Here, the light source may be an artificial light source, sunlight, etc., but the photocatalyst needs to have bandgap energy that can be excited by light from these light sources.

The plant growth control method according to the present invention is a plant growth control method for controlling the growth of plants that grow by producing ethylene and whose growth is promoted by ethylene. A photocatalyst that is excited to decompose ethylene is placed in a nearly closed space for growing plants, and the photocatalyst is excited by light irradiation. here,
The above-mentioned substantially enclosed space is, for example, a greenhouse or an artificial cultivation room, and the photocatalyst is excited by sunlight or by light from an artificial light source.

[Effect]

According to the freshness keeping method and device according to the present invention, ethylene gas produced from agricultural products is efficiently decomposed through the intervention of a photocatalyst, and carbon dioxide is produced. Therefore, the concentration of ethylene gas, which promotes the ripening of agricultural products, is kept low, and the concentration of carbon dioxide, which is a competitive inhibitor of ethylene action that causes the ripening of agricultural products, is kept high, thus maintaining freshness over a long period of time. be done.

According to the plant growth control method according to the present invention, ethylene gas produced during plant growth is efficiently decomposed through the intervention of a photocatalyst, and carbon dioxide is produced. Therefore, by controlling the arrangement of the photocatalyst and its optical excitation, it becomes possible to control the concentration of ethylene gas and carbon dioxide, thereby controlling the growth of plants.

〔Example〕

Hereinafter, some embodiments of the present invention will be described based on FIGS. 1 to 8 of the accompanying drawings. In addition, in the description of the drawings, the same elements are given the same reference numerals, and redundant description will be omitted.

FIG. 1 is a perspective view of a first embodiment of an apparatus to which the freshness keeping method according to the present invention is applied. A door 2 is hinged to the front surface of the cubic or rectangular parallelepiped container 1 so as to be openable and closable, and agricultural products (not shown) can be stored in or taken out of the agricultural product storage space 4 by operating a handle 3. A receiving shelf 5 is formed projecting from the upper part of the inner surface of the container 1, and a photocatalyst unit 6 is placed here. The photocatalyst unit 6 includes a photocatalyst tray 61, a photocatalyst 62 disposed in a photocatalyst storage space above the tray 61, and a photocatalyst 62 arranged in a photocatalyst storage space above the tray 61.
It consists of a transparent cover 63 that covers the upper side of 2.
A reflecting mirror 7 is fixed to the ceiling of the container 1, and a light source 8 is fixed between the reflecting mirror 7 and the photocatalyst unit 6.

The photocatalyst receiving tray 61 is made of a thin film-like material with air permeability or a filter-like material having countless minute ventilation holes, and is divided into a space in which the photocatalyst 62 is stored (photocatalyst storage space) and the produce storage space 4. Ethylene gas, carbon dioxide, and water vapor can freely flow between them. Specifically, the photocatalyst 62 is in powder form and has a diameter of several tens of micrometers or more, whereas ethylene gas, carbon dioxide, and water vapor have a diameter of several angstroms or less, so the receiving tray has a diameter between these. It is formed of a filter-like material with many ventilation holes. Note that the tray 61 may be formed of a material with no air permeability, and some ventilation holes may be provided in a portion thereof.

Further, the light source 8 emits light with a wavelength of energy capable of exciting the photocatalyst 62 (energy greater than the band gap energy of the semiconductor catalyst), and the transparent cover 63 is made of a material that has the property of transmitting this light. be done. Specifically, the photocatalyst 62
When titanium oxide is used as the material, it is necessary to irradiate light with a wavelength of 410 nm or less, and the light source 8 and transparent cover 63 suitable for this are selected. Note that in order to achieve the effects of the present invention, it is sufficient that the photocatalyst is placed in a closed space and that it is photoexcited.
is not essential; for example, the photocatalyst may be housed in a mesh-like bag and suspended in a closed space.

Next, with reference to FIG. 2, the operation of the embodiment shown in FIG. 1 will be explained.

2 is a longitudinal sectional view of the apparatus of FIG. 1; FIG. As shown in the figure, it is assumed that tomatoes 10 are placed as harvested agricultural products in the agricultural product storage space 4 formed by the container 1, and the door 2 is closed.
Then, the light source 8 is turned on and the photocatalyst housing space 6
It is assumed that the photocatalyst 62 in 4 is photoexcited. Then, as the tomatoes 10 ripen, ethylene gas is generated, which causes the produce storage space 4 to
The ethylene concentration inside increases. This ethylene gas enters the photocatalyst housing space 64 through the photocatalyst receiving tray 61. Then, the photocatalyst 62 that was photoexcited here
Due to this action, ethylene gas is decomposed according to the chemical formula: C ₂ H ₄ +4H ₂ O→2CO ₂ +6H ₂ , and the concentration of ethylene gas is therefore reduced. At the same time, the carbon dioxide gas concentration in the produce storage space 4 increases due to the production of carbon dioxide. As a result of the above, the ripening of tomatoes 10 is suppressed, and freshness can be maintained. Although water (H ₂ O) is consumed in the process of decomposing ethylene, the amount consumed is very small because the amount of ethylene itself is only a few ppm. The moisture (steam) provided by agricultural products is sufficient.

Next, a first modification of the first embodiment will be explained with reference to FIG.

In the first embodiment shown in FIGS. 1 and 2, no particular measures have been taken to keep the produce storage space 4 at a low temperature, and since the light source 8 is provided inside the container 1, the heat generated by the light source 8 is Therefore, the temperature of the produce storage space 4 tends to rise. Some agricultural products, such as bananas, can suffer from low temperature damage (rot), but many can be stored for longer periods of time if kept at low temperatures.

Therefore, the modified example shown in FIG.
By keeping the food at a low temperature, it is possible to further improve its freshness. That is, container 1
A cooling pump 31 is attached to the holder, thereby supplying cold air 32 into the produce storage space 4 to keep the inside of the produce storage space 4 at a low temperature. Further, a light source 8 for exciting the photocatalyst is arranged outside the container 1, and the excitation light is guided to the photocatalyst unit 6 through an optical fiber cable 33. In this way, while decomposing ethylene gas by the action of the excited photocatalyst, the produce storage space 4 is not heated to high temperature by the light source 8, so that the energy consumption of the cooling pump 31 can be reduced. In addition, a shelf 21 attached to the container 1,
10 tomatoes, 11 bananas, 12 cabbages on 22
It becomes possible to maintain the freshness of food for a longer period of time.

Next, a second modification of the first embodiment will be explained with reference to FIGS. 4 to 6.

FIG. 4 is a sectional view showing the overall configuration. As shown, a door 2 is attached to the container 1,
Therefore, by operating the handle 3, the agricultural product storage space 4 can be opened.
On the middle shelves 21-232, there are 10 tomatoes and 1 banana.
1. Agricultural products such as cabbage 12 can be stored and taken out. A catalyst box 69 is attached to the inner surface of the container 1 opposite to the door 2, thereby decomposing ethylene in an atmosphere in the presence of moisture.

The cross-sectional structure of the catalyst box 69 is as shown in FIG. In the same figure, box 691
A plurality of intake holes 692 are formed on the lower wall surface of the
A plurality of exhaust holes 693 are formed in the upper wall surface.
Both the intake hole 692 and the exhaust hole 693 have a bent shape, so that light from inside the box 691 is prevented from leaking to the outside. A bent rib 694 is formed on the inner surface of the box 691 to increase the surface area, and countless photocatalyst powders 69 are formed on the surface of the rib 694.
5 is attached. A light source 8 for photocatalyst excitation is placed in the center of the box 691. Figure 6 shows photocatalyst powder 69 on rib 694.
FIG. 5 is an enlarged cross-sectional view showing a state where 5 is attached. As shown in the figure, an adhesive 696 is uniformly applied to the outer surface of the curved rib 694, and numerous pieces of photocatalyst powder 695 are adhered thereto.

Next, the operation of the above modification will be explained.

First, it is assumed that the container 1 is provided with a cooling pump (not shown), and the container 1 in FIG. 4 also has the function of a refrigerator. It is assumed that tomatoes 10, bananas 11, cabbage 12, etc. are stored in the produce storage space 4 as shown in the figure.

In this state, when the light source 8 shown in FIG. 5 is energized by a power source (not shown) and emits high-energy light containing a large amount of ultraviolet rays, the photocatalyst powder 695 attached to the ribs 694 is optically excited. Furthermore, the air inside the box 691 is heated by the light source 8,
Therefore, the air in the agricultural product storage space 4 flows through the intake hole 69.
The air inside the box 691 is sucked into the box 691 through the air outlet 2, and the air inside the box 691 is exhausted into the produce storage space 4 through the exhaust hole 693. Therefore, convection as shown by the arrows in FIG. 4 will occur within the produce storage space 4, and the ethylene gas generated by ripening of the produce and the moisture released from the produce will flow into the box 691 one after another. It will be sent.

As a result, a decomposition reaction of ethylene gas occurs in the box 691, and air containing a large amount of carbon dioxide and little ethylene gas is successively supplied into the produce storage space 4. Note that the temperature increase caused by the light source 8 at this time is compensated for by the function of a cooling pump (not shown). Further, since the intake hole 692 and the exhaust hole 693 are bent to form a light trap, the ultraviolet rays from the light source 8 that are harmful to the agricultural products etc. do not leak into the agricultural product storage space 4. Furthermore, if the light source 8 is a lamp that emits light of a wavelength that does not generate ozone, the produce storage space 4 will not be filled with harmful ozone.

Next, a second embodiment of the freshness keeping method and apparatus according to the present invention will be described with reference to FIGS. 7 to 9.

This second embodiment uses sunlight or indoor light as a light source to excite the photocatalyst, and the first example is constructed as shown in FIG. 7. In the figure, a container 1 has a housing that is open upward,
A receiving shelf 5 is fixedly installed near the opening on the inner surface. The photocatalyst receiving tray 61 is formed in a size that can be received by the receiving shelf 5, and a powdered photocatalyst 62 is spread on it. When the opening of the container 1 is closed by the transparent cover 63, the produce storage space 4 and the photocatalyst storage space are sealed by the container 1 and the transparent cover 63. Agricultural products are stored with the photocatalyst tray 61 and transparent cover 63 lifted, and after storage, they are placed in a place exposed to sunlight. Then, the photocatalyst 62 is excited by sunlight and the ethylene gas from the agricultural products is decomposed, so that the freshness of the agricultural products is maintained for a long time.

FIG. 8 shows a modification thereof. In this variant,
A photocatalyst unit 6 composed of a photocatalyst receiving tray 61, a photocatalyst 62, and a transparent cover 63 is hinged to the container 1 by a hinge mechanism 40.

Therefore, the photocatalyst unit 6 also functions as the door of the container 1. In this modification, when the photocatalytic unit 6 serving as a door is closed, the top surface of the photocatalytic unit 6 is inclined in one direction, so it is used outdoors (excitation by sunlight).
Even if it rains when the photocatalyst unit 6 is used, rainwater will not accumulate on the photocatalyst unit 6.

FIG. 9 shows another modification. In this example, six photocatalyst units 6a to 6f are propped up on a shelf 41 formed at the top of the container 1, and a transparent cover 42 is attached on top of this. In this example, agricultural products are taken in and out of the agricultural product storage space 4 through a door 2 that is hinged to the front surface of the container 1 (not shown).

Next, a method for controlling plant growth according to the present invention will be explained.

FIG. 10 is a sectional view showing the first embodiment. A greenhouse 72 is built on the ground 71, and this greenhouse 72
A sheet 73 for sealing is spread on the ground 71 inside. A plurality of planters 74 are arranged on the sheet 73, and plants 75 are planted therein. A photocatalyst unit 6 is arranged near the ceiling of the greenhouse 72. Plants 75 produce ethylene gas during the growth process, which increases the ethylene gas concentration within greenhouse 72. Therefore, greenhouse 7
When an appropriate number of photocatalyst units 6 are arranged in the greenhouse 7, the photocatalysts are excited by sunlight and the greenhouse 7
The ethylene gas in 2 is decomposed to produce carbon dioxide. Therefore, the effect of ethylene on the growth of the plants 75 in the greenhouse can be controlled as desired, and the conditions for photosynthesis can be enhanced using carbon dioxide.

FIG. 11 is a sectional view showing the second embodiment. A planter 82 is provided in the artificial cultivation room 81, and a cultivation solution 83 and cultivation mats 84 are placed in it. The cultivation liquid 83 is passed through a hose 86 by a pump 85.
circulated through. In addition, this pump 85
is connected to tank 87. Artificial cultivation room 81
A photocatalyst unit 6 is fixed to the ceiling of the room, and is optically excited by a light source 8 provided below. An ultraviolet absorbing filter 88 is provided below the light source 8 to prevent the plants 75 from being irradiated with ultraviolet rays from the light source 8.

According to this embodiment, the plants 75 grow by the cultivation liquid 83 and the light irradiation from the light source 8 excluding harmful ultraviolet rays, and in the process, ethylene gas is produced.
However, this ethylene gas is decomposed through the photocatalyst in the photocatalyst unit 6 which is excited mainly by the ultraviolet rays from the light source 8, producing carbon dioxide. Therefore, by controlling the number of photocatalytic units 6 or the degree of optical excitation by the light source 8, the ethylene gas concentration in the artificial cultivation chamber 81 can be controlled, and therefore the ethylene effect that affects the growth of the plants 75 can be controlled as desired. can. Moreover, the carbon dioxide produced in the process of ethylene decomposition is
This will promote photosynthesis.

Next, specific examples carried out by the present inventors will be described in order to confirm the effects of the present invention.

Example 1 First, a well-sealed desiccator was used as a storage model, and a photocatalyst receiving tray was set on a receiving shelf near the upper opening of the desiccator. Then, fine titanium dioxide powder (manufactured by Furuuchi Chemical Co., Ltd., 300 mesh) was spread on top of it as a photocatalyst. Aluminum foil was pasted on the sides of the desiccator to prevent light from shining on the produce inside. Please confirm in advance that the lid of the desiccator can sufficiently transmit light with a wavelength of 410 nm or less, which is light with energy greater than the bandgap energy of titanium oxide as a semiconductor photocatalyst. I kept it.

Two fully ripe tomatoes, one fresh lettuce, six fresh broccoli, and five fresh spinach plants were placed inside the desiccator constructed in this way. Then, it was placed outdoors in the sunlight during the winter and left undisturbed for 7 days. Seven days later, when we examined the produce inside, we found the following:

Tomatoes were moderately soft and kept sufficiently fresh. In addition, the surface maintained a shiny (glossy) red color.

Lettuce... There was no visible damage at all and it was fresh.

Broccoli...it was fresh and hot.

Spinach... Some parts were wilted, but it was still quite lively.

Comparative Example 1 Using a desiccator of the same type as in Example 1, the same number of agricultural products of the same kind was put therein, and the desiccator was placed side by side with the desiccator of Example 1 and allowed to stand still outdoors for 7 days. However, the photocatalyst was not set. After 7 days, the produce was taken out and examined, and it looked like this:

The tomatoes...both were overripe and overly soft. In addition, the surface had changed to a dull red color with no shine (gloss).

The lettuce was partially black and rotten.

Broccoli...It was the same as in Example 1.

Spinach...Due to the decomposition of chlorophyll, it turned pale green and the whole thing was wilted.

In addition, when measured by gas chromatography, 7
After a few days, the ethylene concentration on the surface of the agricultural products in Example 1 was less than a fraction of that in Comparative Example 1.

Example 2, Comparative Example 2 Using the same desiccator as in Example 1 and Comparative Example 1, only Example 2 was used as a photocatalyst using the method of B. Kraeutler and AJ Bard (J. Am Chem.
Soc., Vol. 100, No. 13, 1978) titanium oxide supporting platinum was set. and,
A 500W xenon lamp was used as the light source instead of sunlight, and light irradiation was performed for 72 hours in parallel. When the ethylene concentration on the surface of the produce inside the desiccator was examined after 72 hours, the concentration of ethylene in Example 2 was less than a fraction of that in Comparative Example 2.

Example 3, Comparative Example 3 An experiment similar to Example 2 and Comparative Example 2 was conducted inside a large freezer. However, as the light source for exciting the photocatalyst in Example 3, a germicidal lamp from a refrigerator was used instead.
As a result, as in Example 2 and Comparative Example 2, it was found that there was a difference of several times or more in ethylene concentration.

The present invention is not limited to the above embodiments, and various modifications are possible.

For example, various modifications can be made to the shape of the light source and the specific configuration of the photocatalyst unit. In addition, titanium oxide, which is a semiconductor photocatalyst, and titanium oxide supporting platinum have been exemplified as photocatalysts, but if they are excited by light irradiation and decompose ethylene, tin oxide (SnO ₂ ), tungsten oxide ( WO ₃ ), zinc sulfide (ZnS), strontium titanate (SrTiO ₃ ), iron oxide (Fe ₂ O ₃ ), zinc oxide (ZnO), cadmium sulfide (CdS) or silicon (Si). It's okay. however,
Toxicity is an issue when using cadmium, so special measures must be taken to prevent it from falling on agricultural products. Further, from the viewpoint of increasing the surface area of the photocatalyst, it is desirable to form it into a powder form, but it is not limited to this.

〔Effect of the invention〕

As described above in detail, according to the freshness keeping method and apparatus according to the present invention, ethylene gas produced from agricultural products is efficiently decomposed through the intervention of a photocatalyst, and carbon dioxide is produced. Therefore,
The concentration of ethylene gas, which promotes ripening of produce, is kept low, and the concentration of carbon dioxide, a competitive inhibitor of ethylene action, is kept high, thus maintaining freshness over a long period of time. Therefore, the freshness of harvested agricultural products can be easily maintained at low cost in a closed space such as a storage room or refrigerator.

Furthermore, according to the plant growth control method of the present invention, ethylene gas produced during plant growth is efficiently decomposed through the intervention of a photocatalyst, and carbon dioxide is produced. Therefore, by controlling the amount of photocatalyst disposed and its photoexcitation, it becomes possible to control the concentration of ethylene and carbon dioxide, thereby controlling the effect of ethylene. Therefore, the effect is that the growth of plants can be easily controlled at low cost in a closed space such as a greenhouse.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating a first embodiment of the freshness keeping method and apparatus of the present invention, FIG. 2 is a sectional view illustrating the operation of the embodiment shown in FIG. 1, and FIG. 4 is a sectional view of another modification of the first embodiment, FIGS. 5 and 6 are sectional views of the main parts of FIG. 4, and FIG. 7 is a method for maintaining freshness. 8 and 9 are cross-sectional views of modifications of the second embodiment, and FIGS. 10 and 11 are plant growth control methods according to the present invention. FIG. 1... Container, 2... Door, 3... Handle, 4...
...Product storage space, 5...Receiving shelf, 6...Photocatalyst unit, 61...Photocatalyst receiver, 62...Photocatalyst, 63...Transparent cover, 64...Photocatalyst storage space, 69...Catalyst box, 691... Box, 692...Intake hole, 693...Exhaust hole, 69
4...Rib, 695...Photocatalyst powder, 696
...Adhesive, 7...Reflection mirror, 8...Light source, 1
0... Tomato, 11... Banana, 12... Cabbage, 21-23... Shelf, 31... Cooling pump, 3
2... Cold air, 33... Optical fiber cable, 40
... Hinge mechanism, 71 ... Ground, 72 ... Greenhouse,
73...Sheet, 74...Planter, 75...Plant, 81...Artificial cultivation room, 83...Cultivation liquid, 84
... Cultivation Matsut, 85 ... Cultivation liquid pump, 86
...Cultivation liquid hose, 87...Cultivation liquid tank.

Claims (1)

[Scope of Claims] 1. A method for maintaining the freshness of agricultural products that matures by producing ethylene and whose ripening is promoted by ethylene, comprising: a photocatalyst that decomposes ethylene when excited by light; A method for maintaining freshness, characterized in that the photocatalyst is placed in a substantially sealed space containing the agricultural products, and the photocatalyst is excited by light irradiation. 2. The method for maintaining freshness according to claim 1, wherein the photocatalyst comprises titanium oxide or titanium oxide supporting platinum. 3. In a freshness preservation device for maintaining the freshness of agricultural products that mature by producing ethylene and whose ripening is promoted by ethylene, a substantially airtight container forming a storage space for the agricultural products for accommodating the agricultural products. a ventable holding member disposed in the container so as to form a photocatalyst accommodation space in contact with the produce accommodation space; and a photocatalyst disposed in the photocatalyst accommodation space for decomposing ethylene by photoexcitation. A freshness preservation device characterized by: 4. The freshness maintaining device according to claim 3, further comprising a light source disposed in the container so as to irradiate the photocatalyst with light having a band gap energy or higher. 5 a first container in which the container forms the agricultural products storage space; a second container in which the container forms the photocatalyst storage space;
5. The freshness keeping device according to claim 3, further comprising a container. 6. A plant growth control method for controlling the growth of a plant that grows by producing ethylene and whose growth is promoted by ethylene, wherein the plant is exposed to a photocatalyst that decomposes ethylene when excited by light. 1. A method for controlling the growth of plants, characterized in that the photocatalyst is placed in a substantially closed space for growth, and the photocatalyst is excited by irradiation with light having a band gap energy or higher.