Apparatus and method for applying gas to plants

Abstract

Provided are a gas application device and a gas application method capable of reducing a pressure loss of an application pipe with a simple structure regardless of a supply source of a target gas, facilitating a change and a design according to a cultivation form of a cultivated plant, and uniformly applying an appropriate amount of the target gas to the cultivated plant even at a place far away from the gas supply source without adversely affecting growth of fruits and harvesting work.SOLUTION: The gas application apparatus of the present invention is constituted by at least an upper member and a reinforcing member, and is configured to apply a target gas from a gas supply source to cultivated plants, so that the installation space can be effectively utilized, the pressure loss becomes very small, and even if the target gas is supplied to a position far away from the gas supply source by a long pipe, an appropriate amount of the target gas can be uniformly applied, the manufacturing cost can be reduced, and the installation work and the recovery work can be easily performed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas application device and application method that can apply a uniform and appropriate amount of target gas to cultivated plants located far from a gas supply source while having a simple structure in the application of gas in a greenhouse, a plant factory, etc. [Background technology]

[0002] In indoor plant cultivation in greenhouses, plant factories, and the like (hereinafter referred to as "greenhouses"), environmental control such as temperature, humidity, solar radiation, and irrigation is carried out. Furthermore, devices and methods for supplying a target gas, such as carbon dioxide, to cultivated plants to promote the growth of cultivated plants have been proposed (e.g., Patent Documents 1 and 2). In the following description, the target gas is assumed to be carbon dioxide.

[0003] In greenhouse cultivation, the flow of outside air is controlled to prevent pests and manage temperature and humidity, but photosynthesis can easily lead to a carbon dioxide deficiency. This tendency for carbon dioxide deficiency is particularly evident in winter, when greenhouses are often closed. For example, strawberries are grown in winter, but in order to maintain the temperature inside the greenhouse, cold outside air is let in and ventilation is performed, making it impossible to increase the carbon dioxide concentration. If there is a lack of carbon dioxide, cultivated plants will not grow properly, resulting in lower yields and affecting agricultural management.

[0004] Carbon dioxide supply devices are considered effective in maintaining an appropriate level of carbon dioxide in greenhouses and increasing productivity. It is said that the carbon dioxide concentration at which plants' photosynthetic rate is highest is 1000-1500 ppm, and even if the concentration is too high, growth rates do not change significantly. On the other hand, when the carbon dioxide concentration is around 400 ppm, the same as in the atmosphere, even a slight drop in carbon dioxide concentration can significantly reduce growth. In this way, if the carbon dioxide concentration can be maintained slightly higher than the outside air, growth can be increased efficiently.

[0005] Carbon dioxide is a raw material for photosynthesis and is applied with the aim of promoting photosynthesis, the plant's production process. Cultivated plants synthesize sugars through photosynthesis, which are then properly translocated, resulting in the enlargement of fruits and other fruit, as well as increased yield and quality. For this reason, producers increase yields by supplying carbon dioxide using carbon dioxide supply devices, and carbon dioxide is particularly used for cultivated plants with high unit prices, such as strawberries and tomatoes.

[0006] Carbon dioxide supply systems are mainly of the combustion type and liquefied carbon dioxide type. Combustion types use exhaust gas from burning kerosene or LPG (Liquefied Petroleum Gas). Kerosene combustion types have an environmental impact, but their introduction and running costs are lower than other types. LPG combustion types have higher combustion efficiency than kerosene combustion types and produce cleaner exhaust gases, but their running costs are higher. Liquefied carbon dioxide types supply pure gas from liquefied carbon dioxide cylinders. While the equipment is cheaper than other types, liquefied carbon dioxide is more expensive than kerosene or LPG, so running costs are higher.

[0007] Combustion is the mainstream method, and it blows out combustion gases with a carbon dioxide concentration of 5-10% into the greenhouse, raising the carbon dioxide concentration throughout the greenhouse. However, during the day, the greenhouse is often left open for ventilation, lowering the temperature inside. With combustion methods, not only does the combustion gas raise the temperature inside the greenhouse, but application methods that raise the carbon dioxide concentration throughout the greenhouse also result in a lot of carbon dioxide leaking outside the greenhouse, making application inefficient. In other words, much of the carbon dioxide is wasted without being used for photosynthesis, contributing to global warming.

[0008] On the other hand, an effective application method is to apply carbon dioxide locally around the leaves of cultivated plants so as to maintain the carbon dioxide concentration at the atmospheric level (about 400 ppm) or a higher concentration than that of the outside air during the time when the photosynthetic rate is at its highest.Even when ventilation is performed during the day when the temperature inside the greenhouse is high, the carbon dioxide concentration around the cultivated plants can be increased by applying carbon dioxide locally near the leaves of the cultivated plants using tubes, ducts, pipes, etc. (hereinafter referred to as "application piping").

[0009] In the liquefied carbon dioxide method, a porous tube is generally used to locally apply carbon dioxide around the cultivated plants. Because the pressure from the cylinder is high, carbon dioxide gradually leaks out of the porous tube. Because high-purity carbon dioxide from the cylinder is applied locally to the leaves, a smaller amount of carbon dioxide gas is required compared to the combustion method, and the same amount of yield increase can be achieved.

[0010] The carbon dioxide application device described in Patent Document 1 is equipped with a blower connected to a combustion-type carbon dioxide generator that generates carbon dioxide, and this blower is connected to a duct and irrigation tube. Carbon dioxide is sprayed from multiple holes provided at regular intervals along the length of the irrigation tube arranged within the cultivated crop canopy. Therefore, even though it is a combustion-type device, carbon dioxide can be applied locally with the greenhouse open, increasing the carbon dioxide concentration within the cultivated crop canopy and maintaining a stable carbon dioxide concentration within the canopy.

[0011] Furthermore, the local gas application system described in Patent Document 2 includes a gas supply source, a main pipe connected to the gas supply source, and an application pipe connected to the main pipe and having a diameter smaller than that of the main pipe. Multiple application pipes are connected to the main pipe, and multiple small holes are provided at predetermined intervals along the longitudinal direction of the application pipe. The system also includes a relay pipe connected between the main pipe and the application pipe, and the diameter of the relay pipe is smaller than that of the main pipe but larger than that of the application pipe. This allows for a simple configuration and low cost to ensure a uniform gas emission rate, enabling gas to be locally emitted to crops grown in each furrow.

[0012] Application using combustion or liquefied carbon dioxide requires the regular purchase of fuel and cylinders, and it is difficult to say that it effectively utilizes carbon dioxide, the main cause of global warming. Combustion methods also generate heat, which is a disadvantage in the summer. Furthermore, greenhouses sometimes require temporary power supply for night lighting, heating, and cooling to control the timing of growing and shipping when cultivated plants are in short supply, in need, or at high prices. The cost of the power receiving equipment and the power receiving contract fees for this are also a burden.

[0013] A carbon dioxide supply device using a honeycomb rotor has been proposed as a new gas supply source (carbon dioxide supply device) to replace combustion and liquefied carbon dioxide systems (see, for example, Patent Document 3). In the honeycomb rotor carrying a carbon dioxide adsorbent, the honeycomb adsorbs and separates carbon dioxide by passing the target air, such as atmospheric air or greenhouse air, through the adsorption zone. In the desorption zone, regenerated air heated in a heating section is passed through to desorb the carbon dioxide, and the regenerated air with an increased carbon dioxide concentration is continuously supplied to the cultivated plants. This allows for the application of clean gas without placing a burden on the environment. The regeneration temperature is low, approximately 40°C (all temperatures hereafter are in degrees Celsius), allowing the use of renewable energy, exhaust heat, and heat pumps. This reduces running costs compared to other systems, and by applying carbon dioxide to cultivated plants, it is possible to increase yields and reduce carbon dioxide emissions. Unlike combustion and liquefied carbon dioxide systems, there is no need to purchase fuel or cylinders. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-153459 [Patent Document 2] Utility Model Registration No. 3212877 [Patent Document 3] Japanese Patent Application Laid-Open No. 2023-110694 Summary of the Invention [Problem to be solved by the invention]

[0015] In the combustion type, when carbon dioxide is filled inside the greenhouse, ventilation has a large effect, and there is a problem that a lot of carbon dioxide is wasted. For example, if the cultivated plants are strawberries, if the temperature inside the greenhouse exceeds 25°C, it will affect their growth, so it is necessary to lower the temperature inside the greenhouse by opening the ceiling or sides of the greenhouse to let in outside air. In this case, the carbon dioxide that has filled the greenhouse will be released outside. In addition, sulfur compounds (SO X ) and nitrogen compounds (NO X There are concerns about the impact of greenhouse gases, such as ozone and carbon monoxide (CO), on cultivated plants and humans. Furthermore, rising fuel prices can lead to reduced profits.

[0016] The carbon dioxide application device described in Patent Document 1 can locally apply carbon dioxide to cultivated plants even if the gas supply source is a combustion type by supplying carbon dioxide through multiple holes formed in the irrigation tube. However, because the spacing between the holes (hole pitch) is constant along the length, a sufficient amount of gas flows out from the holes close to the gas supply source, but the amount of gas flowing out from the holes farther from the gas supply source decreases, resulting in an inconsistent amount of carbon dioxide and variation in the amount of gas supplied to the cultivated plants. This problem is particularly pronounced in large greenhouses, resulting in variation in the growth of cultivated plants.

[0017] The local gas application system described in Patent Document 2 uses a gas generator or a cylinder as a gas supply source, and is equipped with a blower fan to deliver the gas. While a supply source with high gas pressure, such as a cylinder, can be used without a blower fan, a blower fan must be installed when using a gas supply source with low gas pressure, such as a combustion-type gas supply. When the gas supply source is a liquefied carbon dioxide gas type, the cylinder is heavy, making it difficult to transport and replace.

[0018] Localized application of carbon dioxide typically involves the use of porous tubes or application pipes such as the irrigation tubes described in Patent Document 1 and the application pipes described in Patent Document 2. The diameter of the irrigation tubes described in Patent Document 1 is not particularly limited, while the diameter of the application pipes described in Patent Document 2 is preferably approximately 100 to 500 mm. In the case of soil-grown strawberries, straw baskets are sometimes installed between rows to prevent water rot, and irrigation tubes are passed underneath (in the case of two-row planting and endogenous cultivation). For this reason, the space underneath the straw baskets is limited, allowing only irrigation tubes approximately 50 mm wide to fit. Unless the gas supply source provides high pressure, the gas can only reach approximately 20 m. However, in greenhouses as long as 60 m, for example, a small diameter application pipe at locations far from the gas supply source can result in pressure loss, potentially resulting in no carbon dioxide emission or low gas outflow, resulting in low concentrations.

[0019] As the application distance increases, the impact of pressure loss becomes greater, so when applying carbon dioxide all the way to the end of a large greenhouse, it is necessary to increase the carbon dioxide supply pressure or increase the size of the application piping to reduce pressure loss. Increasing the carbon dioxide supply pressure requires changing the size of the blower, which leads to an increase in size and initial and running costs.

[0020] On the other hand, increasing the size of the application pipe to reduce pressure loss reduces installation space, hindering fruit growth and harvesting. Patent Document 2 recommends that vinyl application pipes (polyducts) be used to reduce costs. When carbon dioxide is pumped into the polyduct, the polyduct expands and its cross section becomes circular. For example, consider the use of this circular polyduct as application pipe for soil-grown strawberries. Strawberries are placed on straw racks attached between rows. Therefore, even if the diameter of the application pipe is increased to reduce pressure loss, the space available for installing the polyduct on the straw rack between rows is limited. Furthermore, as shown in Figure 1, strawberry fruits can become hidden under the polyduct, resulting in harvesting errors and requiring the fruit to be pulled out from under the duct during harvesting, which reduces harvesting efficiency. Furthermore, the duct blocks sunlight from reaching the leaves. During nighttime periods when gas is not being applied, the duct shrinks and covers the fruit, crushing them. Furthermore, the accumulation of dew can reduce fruit quality.

[0021] In view of the above circumstances, the present invention provides a gas application device and application method that are simple in structure, reduce pressure loss in application piping, are easy to modify and design according to the cultivation form of cultivated plants, do not adversely affect fruit growth or harvesting operations, and can uniformly apply an appropriate amount of target gas to cultivated plants even in locations far from the gas supply source, regardless of the target gas supply source. [Means for solving the problem]

[0022] In order to solve the above problems, the gas application device of the present invention is characterized in that the cross-sectional shape of the application piping is flattened and is composed of at least an upper member and a reinforcing member, and is designed to apply the target gas from the gas supply source to cultivated plants. [Effects of the Invention]

[0023] The gas application device of the present invention has a simple structure, yet allows for a large cross-sectional area through which the target gas passes without increasing the height compared to the application piping described in Patent Documents 1 and 2. This reduces pressure loss, allowing for a uniform and appropriate amount of target gas to be applied even when supplied to a location far from the gas supply source via a long piping. Furthermore, the installation space can be effectively utilized, without compromising harvesting workability or fruit quality. Therefore, there is no need to pressurize the gas as with a gas cylinder, and it can be applied to various gas supply sources.

[0024] The components used in the application piping of the present invention are inexpensive and easy to process, reducing manufacturing costs. Furthermore, the application piping is water-resistant and durable, lightweight, and foldable, making it easy to carry and compact when stored, facilitating installation and retrieval. This allows for easy replacement and repositioning. The selection of application piping components, the height and width (base), and the size and spacing of the holes can be freely determined, making it easy to design and modify depending on the type and size of the cultivated plants, as well as the purpose and use.

[0025] Furthermore, since the gas application device and application method of the present invention apply the target gas locally near the cultivated plants, even when ventilation is performed, the gas concentration near the cultivated plants does not decrease, and the target gas can be reduced from being released outside the greenhouse, etc.

[0026] Furthermore, when the application piping of the gas application device according to the present invention is installed in soil strawberry cultivation, the application piping collapses when the target gas is not being applied, such as at night, and expands when the target gas is being applied, providing good visibility when the target gas is being applied. Because the cross section is flattened and semi-cylindrical, moisture that accumulates above the application piping at night, etc., falls downwards when the application piping expands, preventing water from accumulating on the piping. If the strawberries are placed on the application piping, the strawberries are not damaged and are prevented from becoming dirty, eliminating the need for a straw rack. Furthermore, since the strawberries are placed on the application piping, visibility during harvesting can be ensured. [Brief explanation of the drawings]

[0027] [Figure 1] Figure 1 shows the layout of a conventional circular application pipe in soil strawberry cultivation. [Figure 2] FIG. 2 is a diagram showing the flow of the gas application device of the present invention. [Figure 3] Figure 3(a) is a cross-sectional view and an oblique view of the flattened kamaboko-shaped application piping of the gas application device of the present invention, Figure 3(b) is a diagram comparing the cross-sectional shapes of the conventional circular application piping and the flattened kamaboko-shaped application piping of the present invention, and Figure 3(c) is a diagram showing the definition of the flattened kamaboko shape in the present invention. [Figure 4] FIG. 4 is a diagram showing the arrangement of a flat semi-cylindrical gas application pipe of the gas application device according to the present invention in soil strawberry cultivation. [Figure 5] FIG. 5 is a diagram showing the configuration of application piping according to the first embodiment of the gas application device of the present invention. [Figure 6] FIG. 6 is a diagram showing the configuration of application piping according to the second embodiment of the gas application device of the present invention. [Figure 7] FIG. 7 is a diagram showing the configuration of application piping according to the third embodiment of the gas application device of the present invention. [Figure 8] FIG. 8 is a diagram showing the configuration of application piping according to the fourth embodiment of the gas application device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] Figure 2 shows the flow of the gas application device according to the present invention. The gas application device 1 of the present invention is provided with a blower 3 on a gas supply source 2, and application piping 4 is connected to this blower 3 via a main duct (not shown) or the like. Application piping 4 is provided for each row of cultivated plants. The target gas supplied from the gas supply source 2 is supplied directly or mixed with air as necessary to application piping 4 provided in the greenhouse by the blower 3, and the target gas is applied to the cultivated plants through multiple holes 5 provided on the side of application piping 4.

[0029] The application piping 4 of the gas application device 1 of the present invention, as will be described in detail later, allows for a larger cross-sectional area through which gas passes without increasing the height, compared to gas application using the irrigation tube of Patent Document 1 or the application pipe of Patent Document 2. This reduces pressure loss, allowing for a uniform and appropriate amount of target gas to be applied even when supplied to a location far from the gas supply source through a long piping. Therefore, there is no need to pressurize the gas as with a gas cylinder, and it can be applied to various gas supply sources. Therefore, the gas supply source 2 is not limited. For example, if the target gas is carbon dioxide, various gas supply sources can be applied, such as combustion-type, liquefied carbon dioxide-type, a carbon dioxide supply device using a honeycomb rotor as described in Patent Document 3, and a carbon dioxide tank concentrated by pressure swing adsorption (PSA)-type. If the gas supply source is high-pressure, such as a cylinder or PSA tank, the blower 3 is not necessarily required. Note that the number of gas supply sources 2 is not limited to one, and multiple sources may be combined. The capacity of the blower 3 is determined by the size of the greenhouse and the area of ​​the carbon dioxide application area. When using liquefied carbon dioxide gas or a carbon dioxide tank, the carbon dioxide from the gas cylinder or gas tank can be mixed with air to adjust the carbon dioxide concentration to a predetermined level, and then the gas can be applied using the gas application device 1 of the present invention.

[0030] When a gas supply device using a honeycomb rotor, such as that described in Patent Document 3, is used as a gas supply source, the target gas leaving the honeycomb rotor is supplied at atmospheric pressure, making the gas application device of the present invention particularly suitable. By adjusting the gas flow, regeneration temperature, rotor rotation speed, etc., the concentration of the target gas can be changed depending on the application and purpose. When the target gas is carbon dioxide, a gas supply device using a honeycomb rotor can be used to concentrate and recover carbon dioxide from the atmosphere or in a greenhouse while simultaneously supplying carbon dioxide to cultivated plants, allowing for the application of clean gas with no environmental impact.

[0031] The gas application piping 4 used in the gas application device 1 of the present invention is installed at the bottom of the cultivated plants (above the furrows) and sprays carbon dioxide near the leaves growing in this area (Figure 4). By spraying carbon dioxide from below, carbon dioxide can be applied to the underside of the leaves, which have many stomata, and this location is preferable because it reduces the leaf surface boundary layer resistance that inhibits carbon dioxide absorption by the leaves. The installation location is not limited to this, and it can also be installed, for example, near the growing point.

[0032] Generally, the cross-sectional shape of the application pipe is rectangular, circular, elliptical, etc. However, the cross-sectional shape of the application pipe 4 of the present invention is a flattened semi-cylindrical shape (hereinafter referred to as "flattened semi-cylindrical shape") as shown in Figure 3(a). The bottom of the flattened semi-cylindrical application pipe (hereinafter referred to as "flattened semi-cylindrical application pipe") is placed flat on the ground, and when combined with the upper part through which the target gas is ventilated, it forms a flattened semi-cylindrical shape, allowing the cross-sectional area to be increased without increasing the height of the application pipe 4 or while lowering the height of the application pipe 4. Increasing the cross-sectional area reduces pressure loss and enables long-distance application even when far from the gas supply source. In addition, multiple holes 5 are provided on the left and right sides of the upper longitudinal portion of the application pipe 4.

[0033] As shown in the left diagram of Figure 3(b), a conventional general application pipe is an application pipe with a circular cross section (hereinafter referred to as "circular application pipe"), and its diameter is d. On the other hand, the cross section of the flattened semicircular application pipe used in the present invention is a semicircle with a diameter of 2d, as shown in the center diagram of Figure 3(b). That is, the diameter (base) of the semicircle is 2d, twice the diameter of the circle in the left diagram of Figure 3(b), and the radius (height) of the semicircle is d, the same as the diameter (height) of the circular pipe. In this case, the cross-sectional area of ​​the circle in the left diagram of Figure 3(b) is (πd 2 ) / 4, whereas the cross-sectional area of ​​the semicircle in the center of Figure 3(b) is (πd 2) / 2, the cross-sectional area of ​​the semicircle in the center of Figure 3(b) is twice that of the circle in the left diagram of Figure 3(b). In this way, for example, if a semicircular flattened semicircular application pipe is used, the cross-sectional area can be made larger even if the height is the same as that of a circular application pipe. In this case, the pressure loss of the flattened semicircular application pipe can be reduced to about 20% of that of a circular application pipe, and the reach of the target gas can be extended by about 5 times.

[0034] Also, the cross section of the flattened semi-ellipse application pipe is a semi-ellipse with a major diameter of 2d and a minor diameter of d, as shown in the right diagram of Figure 3(b). That is, the major diameter (base) of the semi-ellipse is twice the diameter of the circle shown in the left diagram of Figure 3(b), i.e., 2d, and the minor radius (height) is half the diameter (height) of the circular pipe, i.e., 1 / 2d. In this case, the cross section area is (πd 2 ) / 4, which is the same as the cross-sectional area of ​​the circle in the left diagram of Figure 3(b). In this way, for example, if the flattened kamaboko-shaped application pipe is semi-elliptical, the height can be lower than that of a circular application pipe without changing the cross-sectional area. Not limited to the semicircular or semi-elliptical shapes of Figure 3(b), the flattened kamaboko-shaped application pipe can be designed and modified to suit the application form by adjusting the height, width (base), and curvature. Note that the application pipe expands while the target gas is being supplied and contracts when not being used. Therefore, in this specification, "flattened kamaboko-shaped" refers to the cross-sectional shape of the application pipe while the target gas is being supplied.

[0035] Here, if the shape is a flattened semi-cylindrical pipe, there are no restrictions on the ratio of width (base) to height or the curvature. However, if restrictions are imposed, the height h should be in the range of 1 / 10w to 2 / 3w, assuming the width is w. Also, as shown in Figure 3(c), the curved portion of the flattened semi-cylindrical pipe (arc BC or B'C) is included within the range of right-angled triangles ABC and A'B'C, respectively, when the line segments BC and B'C connecting the vertex C in the height direction of the flattened semi-cylindrical pipe and the end point of the base (vertex B or B') are taken as the hypotenuses of the right-angled triangles, and is a curve that is convex toward angle A or A'. Arcs BC and B'C do not necessarily have to be symmetrical. Furthermore, because the material forming the application pipe 4 is flexible, it may not be strictly an arc in practice.

[0036] For soil-grown strawberries, ridges are created and planted to improve drainage and aeration. For example, the bed width is 700 mm, the aisle width is 400–500 mm, and the ridge width is 1100–1200 mm (for two-row planting). The row spacing is 400 mm, the plant spacing is 300 mm, and the ridge height is 200–300 mm for clayey soil with poor drainage, 100–200 mm for fields with intermediate soil texture, and flat, low-rise ridges (flat beds) are acceptable for well-drained sandy soil. Strawberries produce inflorescences (fruit) on the opposite side of the runner (parent plant). Depending on harvesting ease and other factors, seedlings are planted in accordance with the orientation of the fruit, such as the row side or aisle side. Strawberry soil cultivation methods include both indoor and outdoor cultivation. In indoor cultivation, as shown in the photographs in Figures 1 and 4, the plants are planted at both ends of the ridges and grown so that the strawberry fruits are in the center between the rows. In outdoor cultivation, the strawberries are grown so that the fruits are in the side of the ridges (the aisle side). In either cultivation method, it is preferable to place the flat semi-cylindrical application pipe in the center between the rows on the ridges or on the side of the ridges. If the space for placing the pipe is flat, the height of the pipe should be determined taking into account the height of the strawberry plants and how the fruits develop. However, if the center or side of the ridge is raised or sunken, this height should be taken into consideration. On the other hand, if the application pipe is placed in the aisle, the height of the ridge must be taken into consideration.

[0037] Strawberry fruits hang from the ends of stems extending from the base of the plant (crown). Therefore, the fruits grow at the same height as or lower than the ridges. Strawberry plants are short, approximately 300 mm tall, but to allow the strawberries to ripen (to improve harvesting efficiency and allow light to reach the fruit more efficiently), string is sometimes hung 150–200 mm above the ridges to prevent the strawberry leaves from falling toward the fruit. If the application piping is too high, it will shade the strawberry fruit, adversely affecting its growth. Taking into consideration the strawberry fruit height, harvesting ease, and ridge height, the upper limit of the application piping height (h) is set to 200–250 mm, preferably 150 mm. If the application piping height (h) is too low, pressure loss increases, making it impossible to supply the target gas over long distances. Therefore, the lower limit of the height (h) is set to 20 mm. The width (bottom) of the application pipe is, for example, 400 mm between rows, but in order not to interfere with strawberry cultivation, the upper limit of the width (bottom) w is set to 300 to 350 mm, more preferably 250 mm. If the width w is too narrow, the pressure loss will increase, so the lower limit is set to 50 mm.

[0038] When the flattened kamaboko-shaped application pipe of the gas application device according to the present invention is installed in soil strawberry cultivation, as shown in Figure 4, the bottom of the flattened kamaboko-shaped pipe comes into contact with the ground (or a straw rack), preventing the strawberries from getting under the application pipe. This allows for effective use of the installation space and does not impair harvesting or fruit quality. Furthermore, the application pipe deflates when target gas is not being applied, such as at night, and expands when target gas is being applied, providing good visibility when the target gas is being applied. Because the cross section is flattened, moisture that accumulates above the application pipe, such as at night, falls to the bottom when the application pipe expands, preventing water from accumulating on the pipe. As long as the strawberries are placed on the application pipe 4, the strawberries are not damaged and are protected from dirt, eliminating the need for a straw rack. Furthermore, because the strawberries are placed on the application pipe 4, visibility during harvesting is also ensured.

[0039] The overall length of the application piping 4 is not limited, but is determined depending on the length of the greenhouse and the rows of cultivated plants, and is, for example, 30 m for a medium-sized greenhouse and 60 m for a large greenhouse. It is preferable that one end of the application piping 4 on the gas supply source side is connected to a main duct (not shown), and the other end is sealed to prevent leakage of the target gas.

[0040] A plurality of holes 5 are formed on the left and right side surfaces of the upper portion of the application pipe 4. These holes 5 may be burned in with a laser or punched out with a punch or the like, but are not limited to these methods. The size, spacing, arrangement, position, and number of the holes 5 are appropriately formed depending on the size of the application pipe 4, the spatial extent of the greenhouse, and the type and size of the cultivated plants. The size of the holes 5 is, for example, 0.5 to 10 mm, and the spacing between the holes is, for example, 100 to 500 mm, but is not limited thereto. For example, the holes 5 may be formed only in one location on the upper portion of the application pipe 4, or in two locations on the left and right sides of the upper portion of the application pipe 4. When two locations are formed on the left and right sides, they may be arranged in a staggered pattern. The number of holes 5 may be increased or the opening area of ​​the holes 5 may be increased as the distance from the gas supply source 2 increases. Furthermore, by making the spacing between the holes 5 farther from the gas supply source 2 longer than the spacing between the holes 5 closer to the gas supply source 2, the gas supply amount can be made uniform even when the application pipe 4 is long. The amount of gas supplied may be adjusted by increasing the cross-sectional area of ​​the application pipe 4 as it becomes farther from the gas supply source 2 .

[0041] By adjusting the flow rate appropriately using the application piping 4, air containing the target gas is supplied to the leaves of cultivated plants, air is exchanged, stagnation of air and temperature variations are eliminated, transpiration is promoted, and the uptake of water and nutrients by the roots is encouraged, which has the effect of promoting growth.In addition, the leaf surface boundary layer resistance is reduced, further increasing the photosynthetic rate, which achieves both promotion of plant growth and reduction in airflow power, leading to reduction in cultivation costs.

[0042] (First embodiment) As a first embodiment of the gas application piping 4 used in the gas application device 1 of the present invention, FIG. 5 shows the simplest configuration consisting of an upper member 6 and a reinforcing member 7. The flattened, semi-cylindrical space surrounded by the upper member 6 and the reinforcing member 7 is referred to as the upper space 9. The upper member 6 is preferably made of a flexible material that expands when the target gas is supplied and contracts when the supply is stopped. Furthermore, an airtight and waterproof material is used to allow the target gas to pass through. For example, vinyl is preferable. The reinforcing member 7 is preferably a hard plate-like material that supports the expansion and contraction of the upper member 6 at its bottom and maintains the flattened semi-cylindrical shape. Examples include wood boards, metal plates, and resin boards. The plate-like reinforcing member 7 prevents the flattened semi-cylindrical bottom from bending and deforming even when the target gas is ventilated into the upper space 9, maintaining a flat state. Resin boards are preferred due to their low cost, ease of processing, and durability. In particular, plastic cardboard is suitable for the reinforcing member 7 because it is lightweight and inexpensive, and has excellent water resistance, durability, chemical resistance, heat insulation, and sound insulation properties, and is easy to process.

[0043] The upper member 6 and the reinforcing member 7 are connected by clamping, gluing, welding, or other means to prevent target gas leakage. For example, the connection portion (connection portion 8) between the upper member 6 and the reinforcing member 7 is welded using a heat sealer or hot sealer. As shown in the connection example shown in Figure 5(a), the upper member 6 and the reinforcing member 7 are connected via the connection portion 8. At this time, the excess end outside the welded connection portion 8 may be cut off. In this way, the upper member 6 and the reinforcing member 7 are integrally connected along the length of the application pipe 4. When welding, the upper member 6 is preferably made of a thermoplastic material (resin film or sheet) such as nylon, polyethylene, polypropylene, or polyvinyl chloride, which can be welded. Furthermore, the reinforcing member 7 is preferably made of a weldable thermoplastic resin plate (plastic plate), such as polyethylene, polyvinyl chloride, polypropylene, polystyrene, ABS (acrylonitrile butadiene styrene), acrylic, or PET (polyethylene terephthalate) resin plate.

[0044] As shown in the central drawing of Figure 5(a), by wrapping the upper member 6 under the reinforcing member 7, when the target gas is ventilated into the upper space 9, the upper member 6 expands, causing tensile force that prevents the upper member 6 from peeling off from the reinforcing member 7. Furthermore, since the greenhouse is long, e.g., 60 m, the reinforcing member 7 may be formed by connecting multiple reinforcing members 7 along its length, as shown in Figure 5(b). In this case, the joints may be connected using the same sheet material as the upper member 6, or the thickness of the reinforcing member 7 may be reduced only at the joints, making it foldable. This foldable design facilitates portability. Furthermore, using transparent materials for the application piping 4 provides excellent lighting and does not block sunlight from reaching leaves, fruits, etc. The materials and color of the application piping can be determined depending on the purpose and application. As described above, the application piping of the present invention can be easily designed and modified to suit the purpose and application. The application pipes 4 may be connected to each other in the longitudinal direction by means of clamping, bonding, welding, or the like, or by using tape, clips, or the like.

[0045] The upper member 6 and the reinforcing member 7 are lightweight, and the application pipe is small enough that a single user can carry it, making installation and recovery easy. Furthermore, since the pipe is deflated when the target gas is not passing through, it is easy to store. Because the application pipe used in the present invention can be easily installed and removed, it can also be easily replaced or relocated.

[0046] (Second embodiment) Figure 6 shows a second embodiment of the gas application piping 4 used in the gas application device of the present invention. Explanations of parts that overlap with the first embodiment will be omitted. In the second embodiment, the application piping 4 is composed of two layers of sheet members, an upper member 6 and an intermediate member 10, and the flat, semi-cylindrical space surrounded by the upper member 6 and the intermediate member 10 or the reinforcing member 7 is the upper space 9. As shown in Figure 6(a), the reinforcing member 7 is positioned below the intermediate member 10, or as shown in Figure 6(b), it is positioned above the intermediate member 10 so that it is contained within the upper space 9.

[0047] The upper member 6 and intermediate member 10 of the application pipe 4 can be made of, for example, a general vinyl polyduct (polyduct tube). Polyduct is easily available in the required size, has excellent workability, is inexpensive, and is compact when stored, facilitating installation and retrieval. Because the polyduct is cylindrical, the upper member 6 and intermediate member 10 are already integrally formed. A reinforcing member 7 is placed below the polyduct as shown in Figure 6(a), or the reinforcing member 7 is inserted into the hollow of the polyduct (in the upper space 9) as shown in Figure 6(b), connecting the intermediate member 10 to the reinforcing member 7. In this case, both ends of the application pipe 4 along the length (longitudinal direction) may be connected by means of clamping, bonding, welding, or the like, or the surfaces where the intermediate member 10 and the reinforcing member 7 meet may be connected by adhesive or the like. In this way, the application pipe 4 is formed by integrally forming the upper member 6, intermediate member 10, and reinforcing member 7 along the length.

[0048] In addition, in Figure 6(b), the reinforcing member 7 and the intermediate member 10 may be connected only at the center of the bottom surface of the reinforcing member 7 along the length direction by means of adhesive bonding, welding, or the like. In this case, as shown in Figure 6(c), the connection portion 8 is only at one point on the bottom surface of the reinforcing member 7, so there are fewer connection points and it is easier to manufacture and process. When the target gas is ventilated in Figure 6(c), the target gas passing through the upper space 9 also flows into the space surrounded by the bottom surface of the reinforcing member 7 and the intermediate member 10, and two smaller flattened semi-cylindrical shapes similar to the flattened semi-cylindrical shape of the upper space 9 are formed on the underside of the reinforcing member 7.

[0049] (Third embodiment) FIG. 7 shows a third embodiment of the application piping 4 used in the gas application device of the present invention. In the third embodiment, the application piping 4 is composed of three layers of sheet members: an upper member 6, an intermediate member 10, and a lower member 11. The upper space 9 is surrounded by the upper member 6 and the intermediate member 10, and the lower space 12 is surrounded by the intermediate member 10 and the lower member 11. The target gas is ventilated into the upper space 9 between the upper member 6 and the intermediate member 10, and a reinforcing member 7 is inserted into the lower space 12 between the intermediate member 10 and the lower member 11. By ventilating the target gas into the upper space 9, the upper space 9 expands, and the cross section of the upper space 9 is maintained in a flattened semi-cylindrical shape. The lower space 12 is maintained by the reinforcing member 7 so that the bottom surface of the application piping 4 is flat. The thickness of the lower space 12 is approximately the same as the thickness of the reinforcing member 7, and the cross section of the lower space 12 is approximately linear. Therefore, the cross-sectional shape of the application pipe 4, which is a combination of the upper space 9 and the lower space 12, is generally a flattened semi-cylindrical shape.

[0050] As in the second embodiment, a polyduct can be used for the upper member 6 and intermediate member 10 of the application pipe 4. Because the polyduct is formed in a cylindrical shape, the upper member 6 and intermediate member 10 are already formed as a single unit. A lower member 11, such as a single vinyl sheet, is placed under the polyduct, and both ends are connected along the length (longitudinal direction) by means of clamping, gluing, welding, or the like. In this way, the application pipe 4 is formed by integrating and connecting the three layers of sheet members, the upper member 6, intermediate member 10, and lower member 11, at the connection portion 8 in the longitudinal direction.

[0051] For example, a heat sealer or hot sealer is used to weld the longitudinal ends of the vinyl lower member 11, which is overlapped with the poly duct upper member 6 and the intermediate member 10. At this time, excess ends outside the welded joints may be cut off. When welding, weldable thermoplastic materials such as nylon, polyethylene, polypropylene, and vinyl chloride are preferred for the upper member 6, the intermediate member 10, and the lower member 11. Airtight and waterproof materials are used for the upper member 6 and the intermediate member 10 to allow the target gas to pass through. Furthermore, the upper space 9 formed by the upper member 6 and the intermediate member 10 are connected so that gas does not leak from the joint 8. Alternatively, a nonwoven fabric sheet may be used for the lower member 11. Nonwoven fabric has good breathability and water permeability, making it less likely for water to accumulate in the lower space 12. Using a fine-mesh nonwoven fabric sheet can prevent soil from entering the lower space 12.

[0052] A reinforcing member 7 is inserted into the lower space 12 so that the bottom surface of the application pipe 4 is flat. As mentioned above, the reinforcing member 7 can be a plate-shaped member such as plastic board, plywood, or metal plate. The plate-shaped reinforcing member 7 prevents the flat, semi-cylindrical bottom surface from bending and deforming even when the target gas is ventilated into the upper space 9, thereby keeping the bottom surface of the application pipe 4 flat.

[0053] Plastic board is particularly suitable for the reinforcing member 7 because it is lightweight, inexpensive, easy to process, and has excellent water resistance, durability, chemical resistance, thermal insulation, and soundproofing properties. Furthermore, because plastic board is electrostatically charged, it is also suitable for use with vinyl materials such as the intermediate member 10 and lower member 11, which tend to adhere to each other due to electrostatic forces. When using plastic board as shown in Figure 7, the harmonica-shaped hollow structure (hereinafter referred to as the "hollow surface") formed by the ribs is aligned along the longitudinal direction (connection portion 8) of the application pipe 4, thereby increasing the ability to maintain flatness against bending of the bottom surface and preventing the intrusion of debris into the ribs. Furthermore, when connecting the upper member 6, intermediate member 10, and lower member 11, plastic board can be sandwiched between the intermediate member 6 and lower member 11 and connected at the connection portion 8 to form an integrated structure, thereby sealing the ribs and preventing the intrusion of debris and water. This seals the normally exposed hollow surface of the plastic board, preventing the intrusion of debris and water. When inserting plastic board into the lower space 12 as the reinforcing member 7, rounding the four corners of the plastic board can prevent it from getting caught. Plastic board is available in a variety of colors, so you can select the color according to your purpose and use. The reinforcing member 7 and the lower member 11 may be connected by adhesive, welding, or other means at the center of the bottom surface of the reinforcing member 7 along the length direction, and the reinforcing member 7 may be fixed to the lower member 11 to form a single unit.

[0054] In the third embodiment, there is a lower space 12 into which the reinforcing member 7 is inserted, so that reinforcing members 7 of any length can be inserted at intervals, or joined together with tape so that they are foldable, allowing the application pipe 4 to be folded at the joint and carried. Alternatively, the reinforcing member 7 and the application pipe 4 excluding the reinforcing member 7 (the upper member 6, intermediate member 10, and lower member 11, which are integrally formed) may be carried separately. Except when the reinforcing member 7 is integrally formed at the connecting portion 8 or when the reinforcing member 7 is connected to the lower member 11, the reinforcing member 7 is detachable, so that only the reinforcing member 7 can be replaced depending on the purpose and use.

[0055] (Fourth embodiment) In the third embodiment, the lower member 11 is not limited to a single sheet, and a polyduct may also be used. That is, two sheets of polyduct are stacked and connected at both ends along the length (longitudinal direction) by means of clamping, gluing, welding, or the like. In this case, as shown in FIG. 8, the application pipe 4 is composed of four layers of sheet members: an upper member 6, an intermediate member 10, an intermediate additional member 13, and a lower member 11. In addition to the upper space 9 and the lower space 12 separated by these sheet members, a new intermediate additional space 14 is formed surrounded by the intermediate member 10 and the intermediate additional member 13. Because the polyduct is cylindrical, the intermediate additional member 13 and the lower member 11 are already formed integrally. The target gas is ventilated through the upper space 9. As in the third embodiment, the reinforcing member 7 may be inserted into the lower space 12, the intermediate additional space 14, or both spaces. For example, when using plastic board as the reinforcing member 7, the bottom surface of the application pipe 4 may bend due to high target gas flow rates or high pressure near the gas supply source blower. Therefore, two pieces of plastic board are inserted into the intermediate additional space 14 and the lower space 12, respectively. Inserting one piece in the same orientation as the hollow surface of the plastic board in Figure 7 and the other in a 90° rotation so that the hollow surface forms the cross section can further strengthen the flatness of the bottom surface. In the third embodiment, the lower member 11 is a single sheet, which must be processed to a predetermined size. However, in the fourth embodiment, it can be easily formed by stacking commercially available plastic ducts of the same size. The reinforcing member 7 and the lower member 11 or the intermediate additional member 13 may be connected by adhesive, welding, or other means along the length at the center of the bottom surface of the reinforcing member 7, and the reinforcing member 7 may be fixed to the lower member 11 or the intermediate additional member 13 to form an integrated unit.

[0056] Various embodiments of the application piping used in the gas application device of the present invention have been described above, but the present invention is not limited thereto. The basic configuration of the application piping is a flattened semi-cylindrical cross-sectional shape and is composed of at least an upper member and a reinforcing member. Various configurations are possible within the spirit and scope of the present invention. For example, in the fourth embodiment, the target gas is ventilated through the upper space 9, but it may also be ventilated through the intermediate additional space 14. Instead of using one to four sheets of material as in the first to fourth embodiments, five or more sheets of material may be used, and multiple reinforcing members 7 may also be used. In the third and fourth embodiments, the width of the reinforcing member 7 is preferably approximately the same as that of the intermediate member 10, the lower member 11, and the intermediate additional member 13. However, without being limited thereto, if the width of the reinforcing member 7 is made shorter than the widths of the other members, when the target gas is ventilated through the upper space 9, the width of the reinforcing member 7 becomes the base of the flattened semi-cylindrical shape, and the excess width of the intermediate member 10, the lower member 11, and the intermediate additional member 13 deforms to form the flattened semi-cylindrical shape, which does not pose a problem in use.

[0057] Furthermore, for example, a reflective sheet material (such as an aluminum sheet) that reflects light can be used for the upper member 6, or if the members of the application piping other than the reinforcing member 7 (the upper member 6, intermediate member 10, lower member 11, and intermediate additional member 13) are transparent or translucent, a light-reflecting material (such as a metal plate or a plate with an aluminum sheet attached) can be used for the reinforcing member 7. The reflective surface will reflect lighting and sunlight, increasing the light intensity and further increasing the photosynthetic rate, thereby promoting plant growth and reducing lighting power consumption. The reflective surface may be made of reflective material, reflective paint, or other reflective substances.

[0058] The installation position of the application piping of the gas application device of the present invention is not limited to on the ridges, but may be placed above or on the left and right sides of the cultivated plants, or the target gas may be applied from multiple positions around the cultivated plants. In recent years, mobile culture bed systems have been put into practical use, not only for plants cultivated in ridges or in culture beds fixed to the ground, but also for plants cultivated in ridges or in culture beds fixed to the ground. By moving the cultivation benches carrying the cultivation beds, the path area can be reduced, allowing for the installation of more culture beds than fixed systems. Therefore, by installing beams and pillars for installing the application piping in a location that does not interfere with the movement of plants cultivated in ridges or in culture beds, or the movable cultivation beds and their cultivated plants in the mobile culture bed system, gas application to cultivated plants in various cultivation forms can be expanded.

[0059] The carbon dioxide concentration in the outside air is approximately 400 ppm, but the carbon dioxide concentration inside the greenhouse can fall below that of the outside air due to absorption by cultivated plants through photosynthesis. It is effective to measure the carbon dioxide concentration inside the greenhouse to detect when carbon dioxide levels are decreasing, and then apply gas in accordance with the increase in photosynthesis rate during the day, so that the concentration does not fall below the outside air concentration. It is also a good idea to monitor the change in carbon dioxide concentration over time inside the greenhouse and manage it so that it remains at the target concentration. For example, a carbon dioxide concentration detection sensor can be installed near the leaves of cultivated plants, and gas application can be stopped if the concentration exceeds a set upper limit and started if the concentration falls below a set lower limit. In this way, gas concentration detection sensors can be installed as needed, and the amount of target gas, such as carbon dioxide, supplied can be adjusted according to the concentration detected by the sensor.

[0060] Furthermore, by installing an illuminance meter in a location within the greenhouse where the cultivated plants are not shaded, and measuring the illuminance, the supply of the target gas is started when the illuminance reaches a set level or higher, and stopped when the illuminance falls below the set level, it is possible to prevent the application of gas on cloudy or rainy days, or from the evening until night. Alternatively, the application time can be controlled by a timer, so that the target gas is applied only during times when photosynthesis is most active. By using the aforementioned gas concentration detection sensor or a combination of these, more precise gas application can be achieved, and the application of carbon dioxide not used for photosynthesis can be suppressed. Furthermore, the concentration of the target gas, such as carbon dioxide, can be adjusted according to the growth conditions of the cultivated plants. Furthermore, a humidity sensor can be installed as needed.

[0061] For example, if the cultivated plant is strawberry, applying carbon dioxide to the entire greenhouse using a combustion system increases the yield by about 15%. However, as mentioned above, the temperature rises, necessitating ventilation to keep the temperature inside the greenhouse below 25°C, limiting application of carbon dioxide to December through February. On the other hand, with the gas application device and method of the present invention, the carbon dioxide concentration near the plants is maintained even when the roof or sides of the greenhouse are opened for ventilation. This allows the application period to be extended to October through May, which is the strawberry cultivation period, and therefore an increase in yield can be expected. As mentioned above, the application piping of the gas application device of the present invention is particularly suitable for soil-grown strawberries grown in two rows. The cultivated plants and cultivation methods are not limited to these, and the gas application can be applied to various cultivated plants whose quality and yield are improved by application of the target gas, such as elevated strawberries, cucumbers, tomatoes, and melons.

[0062] While the target gas described above is carbon dioxide, this is not limiting. Temperature and humidity control within the greenhouse can be easily achieved by using air conditioning and heating equipment or dehumidifiers as gas supply sources and using warm or cold air or humidity-controlled air. This eliminates temperature and humidity variations within the greenhouse, resulting in uniform plant growth. Furthermore, temperature- and humidity-controlled carbon dioxide may be supplied, or other target gases may be used. The supply of carbon dioxide may be stopped during times when photosynthesis is not occurring, and only humidity-controlled air may be supplied. Supplying humidity-controlled air can prevent the leaves of cultivated plants from drying out when the humidity inside the greenhouse is low, or reduce the humidity around the cultivated plants when the humidity inside the greenhouse is high, thereby promoting efficient photosynthesis and growth. Other target gases that promote or inhibit the growth of cultivated plants may be applied, such as ethylene gas, which has a ripening effect on fruits, suppresses flowering when used on chrysanthemums, and inhibits the elongation and growth of some plants, or nitrogen, which is used to suppress plant growth for purposes such as shipping and procurement.

[0063] In the present invention, the term "house" can be applied to various types of houses, regardless of the type of horticultural facility, such as a sealed house, a house with ventilation means, a house with a net stretched over it, a rainproof house with open sides, or a tunnel house. [Example]

[0064] A carbon dioxide supply device with a honeycomb rotor was used as the gas supply source. The gas application device of the present invention was installed in a greenhouse for soil-grown strawberries (two-row planting, indoor cultivation) as shown in Figure 4, and carbon dioxide was applied. A vinyl duct with a diameter of 150 mm was used as the main duct, and flat, semi-cylindrical application pipes connected to the main duct through branch pipes were placed between each row of soil-grown strawberries. Tape was used for connection. The flat, semi-cylindrical application pipes had a width (base) of 200 mm, a height of 120 mm, and a length of 60 m to match the size of the greenhouse. The carbon dioxide concentration of the recycled air enriched with carbon dioxide from the honeycomb rotor was 650 ppm. It was confirmed that the carbon dioxide concentration from the holes in the flat, semi-cylindrical application pipes remained at 650 ppm even at the furthest point, 60 m, from the gas supply source. Without application, the carbon dioxide concentration in the greenhouse was below the ambient air concentration of 400 ppm during periods of active photosynthesis. On the other hand, by using the gas application device of the present invention, even though ventilation was carried out during the carbon dioxide application period to keep the temperature inside the greenhouse below 25°C, the carbon dioxide concentration around the strawberry leaves (at a position approximately 100 mm away from the application piping hole) was 400 to 500 ppm even at a position 60 m farthest from the gas supply source, and a higher carbon dioxide concentration could be maintained than without application. [Industrial Applicability]

[0065] In gas application for indoor plant cultivation in greenhouses, plant factories, etc., the gas application device and gas application method of the present invention have a simple structure and can uniformly apply an appropriate amount of target gas to cultivated plants located far from the gas supply source without impairing fruit quality or harvesting workability. Furthermore, when the target gas is carbon dioxide, by combining it with a gas supply device using a honeycomb rotor, carbon dioxide from the atmosphere or in the greenhouse can be concentrated and recovered while simultaneously being supplied to cultivated plants, allowing for the application of clean gas without imposing a burden on the environment. [Explanation of symbols]

[0066] 1 Gas application equipment 2. Gas supply source 3. Blower 4 Application piping 5 holes 6 Upper member 7 Reinforcement members 8 Connection part 9 Upper space 10 Intermediate parts 11 Lower member 12 Lower space 13 Intermediate additional members 14 Intermediate additional space

Claims

1. A gas application device for plants, characterized in that the cross-sectional shape of the application pipe for applying target gas from a gas source to plants is a flattened semi-cylindrical shape.

2. 2. The gas application device for plants according to claim 1, wherein the application piping comprises at least an upper member and a reinforcing member.

3. 3. The gas application device for plants according to claim 2, wherein the application piping further comprises an intermediate member.

4. 4. The gas application device for plants according to claim 3, wherein the application piping further has a lower member, and the reinforcing member is disposed in a lower space surrounded by the intermediate member and the lower member.

5. 2. The gas application device for plants according to claim 1, wherein the cross-sectional area of ​​the application pipe on the side farther from the gas supply source is larger than the cross-sectional area of ​​the application pipe on the side closer to the gas supply source.

6. 2. The gas application device for plants of claim 1, wherein the application piping has a plurality of holes.

7. 7. The gas application device for plants according to claim 6, wherein the spacing between the plurality of holes on the side farther from the gas supply source is narrower than the spacing between the plurality of holes on the side closer to the gas supply source.

8. 7. The gas application device for plants according to claim 6, wherein the opening area of ​​the plurality of holes on the side farther from the gas supply source is larger than the opening area of ​​the plurality of holes on the side closer to the gas supply source.

9. 9. A gas application device for plants according to any one of claims 1 to 8, characterized in that the target gas is carbon dioxide, and the gas supply source is at least one of a combustion type, a liquefied carbon dioxide type, a gas supply device using a honeycomb rotor, or a gas tank.

10. A method for applying a gas to a plant, comprising applying the target gas to the plant using the gas application device to the plant according to any one of claims 1 to 8.

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