Environmental control system for controlling the microenvironment of plants

Abstract

To provide an environment control system for an agricultural house that increases the amount of photosynthesis of plants and suppresses disease.SOLUTION: By blowing conditioned air with a gentle breeze, it is possible to increase the amount of photosynthesis and suppress disease damage. The conditioned air is pre-conditioned with a carbon dioxide feeder, a dehumidifier, and a humidifier so that the temperature, humidity / saturation deficit, and carbon dioxide concentration are within a range suitable for plants. Further, by arranging an environmental maintenance curtain above a plant community transplanted to a cultivation bed, the dissipation of carbon dioxide can be suppressed and the carbon dioxide can be applied efficiently at low cost.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an environmental control system for an agricultural greenhouse that locally applies air suitable for plant cultivation. Specifically, it relates to an environmental control system that generates an air current by blowing air with adjusted carbon dioxide concentration, temperature, and humidity to adjust the growth environment of plants. Further, it relates to a system that can increase the number of cultivated plants per unit area and suppress the dissipation of applied carbon dioxide and the temperature drop of the cultivation bed.

Background Art

[0002] Facility cultivation of vegetables, flowers, etc. aims to artificially control the growth environment of plants such as air temperature, ground temperature, light quantity, and soil moisture from the period of low temperature when cultivation is impossible in the open field, and cultivate crops with stable quality throughout the year. Further, since photosynthesis necessary for plant growth is accelerated by increasing the carbon dioxide concentration in the atmosphere, technologies for supplying carbon dioxide and shortening the yield and cultivation period have been developed.

[0003] Photosynthesis is the process by which plants synthesize sugar using light energy with carbon dioxide and water as materials. Since facility cultivation is a closed environment or a semi-closed environment, carbon dioxide may be insufficient during the day when photosynthesis is active. It is said that when carbon dioxide is insufficient, the efficiency of photosynthesis decreases, and as a result, the yield of crops decreases. Therefore, devices have been devised to apply carbon dioxide and maintain high photosynthesis efficiency.

[0004] In addition, in facility cultivation in Japan, temperature adjustment is important. Especially in summer and in areas with strong sunlight, the inside of an agricultural greenhouse (hereinafter, the names of buildings used for facility horticulture such as agricultural greenhouses, greenhouses, greenhouses, and horticultural facilities are used interchangeably with each other.) becomes high temperature throughout the year, which is not suitable for plant growth and is likely to cause high temperature damage, so it is important to perform appropriate temperature management. There are various facilities such as a pad and fan system and a mist system to cool the room temperature inside the greenhouse, but they are not always satisfactory in terms of effect and cost.

[0005] Patent Document 1 describes a carbon dioxide application device that applies carbon dioxide into a crop community not only in a sealed horticultural facility but also in a facility open to the outside air such as a rain shelter house or a tunnel house. A device is disclosed that ejects carbon dioxide generated by a combustion-type carbon dioxide generator installed in a horticultural facility from a duct disposed in the community of cultivated plants in the horticultural facility using a blower to increase the carbon dioxide concentration in the community.

[0006] Patent Document 2 discloses a system for controlling so that carbon dioxide does not flow out of the house even when ventilation is performed to keep the temperature in the house constant. Specifically, a process of driving a carbon dioxide supply device and a subsequent process of prohibiting the driving of the carbon dioxide supply device and diffusing carbon dioxide are repeated until the temperature in the house becomes a certain level or higher, and during that time, the ventilation fan is stopped to suppress the outflow of carbon dioxide to the outside of the house.

[0007] Patent Document 3 discloses an air supply device for a greenhouse that supplies mixed air obtained by mixing outside air and air in the greenhouse to the base of cultivated plants. It is a device that efficiently controls temperature, humidity, and carbon dioxide by controlling the mixing ratio of outside air and air in the greenhouse. Further, it is also disclosed that carbon dioxide generated by a carbon dioxide generator is taken into the mixed air to control carbon dioxide.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] The invention described in Patent Document 1 describes an apparatus capable of increasing the carbon dioxide concentration within a crop community even in an open house. However, in regions belonging to temperate zones such as Japan, even though it is necessary to conduct greenhouse cultivation in a closed type during winter, from spring to summer, ventilation is required due to the occurrence of high-temperature damage. When ventilation is performed, carbon dioxide flows out of the house. Therefore, even if carbon dioxide is applied, the efficiency is extremely poor. Furthermore, in the apparatus of Patent Document 1, since a combustion-type carbon dioxide generator is installed inside the house, there is also a problem that it cannot be used during periods of high temperature.

[0010] The invention described in Patent Document 2 can suppress the outflow of carbon dioxide outside the house, but since constant ventilation is required during periods of high temperature, the carbon dioxide supply apparatus cannot be used. Also, since the carbon dioxide supplied from the carbon dioxide generator is configured to be supplied from the air outlet formed near the base of the horticultural plant, in the case of long-stem plants such as tomatoes and eggplants, carbon dioxide is not supplied near the leaves that perform photosynthesis.

[0011] Patent Document 3 discloses an apparatus that mixes outside air and air inside the greenhouse and controls temperature, humidity, and carbon dioxide. The invention described in Patent Document 3 is suitable for implementing closed-type cultivation without ventilation during the day or semi-closed-type cultivation with ventilation only when the room temperature inside the greenhouse exceeds a predetermined temperature during the day. However, in the cultivation environment of our country, there are many periods when ventilation is required, and there is a problem that the period when it cannot be used is long. Also, since the humidity inside the house is linked to the humidity of the outside air, there is little room to adjust the humidity by mixing the outside air and the air inside the greenhouse. Furthermore, since the air for the greenhouse is configured to be supplied to the base of the plant, similar to the invention of Patent Document 2, in the case of long-stem plants, there is a problem that carbon dioxide is not supplied to the upper part of the plant.

[0012] As described above, none of the inventions is a system that can accommodate all types of horticultural facilities, whether closed or open, and comprehensively adjust temperature, humidity, and carbon dioxide to control the growth environment of plants. In protected cultivation, since the temperature inside the greenhouse rises, ventilation is necessary to avoid heat damage. However, when applying carbon dioxide while ventilating, the outflow of carbon dioxide to the outside air cannot be avoided, resulting in poor efficiency. There is a need to develop a system that can maintain a certain concentration of carbon dioxide without waste throughout the year while appropriately managing temperature and humidity.

Means for Solving the Problems

[0013] The present invention relates to a system for locally supplying air adjusted to a carbon dioxide concentration, temperature, and humidity suitable for plant growth into a plant community to control the plant growth environment. It also relates to a system for suppressing the dissipation of applied carbon dioxide and maintaining heat to maintain a certain environment. (1) An environmental control system in an agricultural greenhouse, characterized by generating an air current by sending a gentle breeze throughout the entire plant community to adjust the microenvironment within the entire plant community. (2) The environmental control system according to (1) includes a mixing cabin for adjusting cultivation air, a carbon dioxide supply device for supplying carbon dioxide, a dehumidifier, and a humidifier. The carbon dioxide concentration, temperature, and humidity are adjusted within a predetermined range in the mixing cabin, and the adjusted air is supplied by a blower tube. (3) The environmental control system according to (2), wherein the carbon dioxide supply device is a combustion-type carbon dioxide generator and can be used for supplying carbon dioxide and managing the temperature of the plant community. (4) The environmental control system according to (2) or (3), wherein the humidifier is a mist generator. (5) The environmental control system according to any one of (1) to (4), wherein sensors for measuring at least temperature and humidity are provided inside and outside the agricultural greenhouse, and the control device adjusts and supplies the prepared air to be mixed. (6) The environmental control system according to any one of (1) to (5), wherein the cultivation bed provided inside the agricultural greenhouse is a hanging bed and is movable in the vertical direction. The environmental control system according to any one of (1) to (6), characterized in that a movable curtain for maintaining the environment is provided. When cultivating low-growing plants, the air supply tube is arranged at the base of the plant, and when cultivating long-stemmed plants, the air supply sub-tube is branched vertically from the air supply tube and arranged, and the conditioned air is supplied to each plant. The prepared air application system for plant cultivation according to any one of (2) to (5).

Advantages of the Invention

[0014] Since it is a system capable of supplying conditioned air for plant cultivation, which has been adjusted so that the temperature, humidity, and carbon dioxide concentration are within an appropriate range for plant growth, to the interior of the plant community, particularly near the leaves that perform photosynthesis, it is possible to increase the yield and suppress diseases while keeping the cost low. Conventionally, it was difficult to supply carbon dioxide during the summer when ventilation was required, but the system shown in the following embodiments can efficiently supply carbon dioxide even under climate conditions where ventilation is required. In addition, by adopting a hanging bed and a curtain extension system, the supplied carbon dioxide can be retained within the community of cultivated plants to suppress dissipation, and the cultivation area per unit can be increased. As a result, not only can a more productive and profitable facility be achieved, but it can also lead to a reduction in carbon dioxide emissions.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0016] Although it will be described in detail in the following embodiments, the prepared air application system for plant cultivation can be applied to any type of horticultural facility, whether it is a closed house, an open house, or otherwise. Since it is a system that applies conditioned air near the plant body to adjust the microenvironment, even in an open house, there is no need to worry so much about the outflow of carbon dioxide outside the facility, and the growth environment of plants can be appropriately maintained at low cost.

[0017] The prepared air application system for plant cultivation can be used for any horticultural crop. For example, it can be used for vegetables such as tomatoes, eggplants, cucumbers, peppers, and paprika, fruits such as strawberries and melons, and furthermore, flower crops such as chrysanthemums, roses, and carnations. For each crop, the carbon dioxide concentration, temperature, saturation deficit (humidity), and soil moisture can be set and adjusted so as to create a suitable environment.

[0018] First, the conditioned air suitable for plant cultivation will be described. The conditioned air to be locally applied is aimed at suppressing the active photosynthesis of the plant community and the occurrence of diseases, and the air is adjusted and blown so that the carbon dioxide concentration, air temperature, and saturation deficit (humidity) are within an appropriate range. By blowing air, an air current can be generated, and the management necessary for growth can be carried out.

[0019] Since the air environment (condition) inside the house is constantly changing, the carbon dioxide concentration, temperature, and saturation deficit (humidity) are automatically and sequentially measured, and based on the results, the air is adjusted and supplied into the house. By controlling the temperature suitable for growth, adjusting the carbon dioxide concentration to increase the photosynthesis amount, and further adjusting the humidity, diseases can be suppressed. In addition, since the fossil fuels used for carbon dioxide concentration and temperature control are locally applied, less is required compared to the case of controlling the entire facility, and the production amount can be increased at low cost. The items managed by this system will be described below.

[0020] [Airflow] The cultivation-adjusted air is supplied as a gentle breeze from the duct to create a state where an airflow occurs within the plant community. When the stomata of plants are open during the day, it is said that the higher the airflow velocity within the range of several cm / s to several tens of cm / s, the better the photosynthesis efficiency. Also, at night, it is preferable to set the airflow velocity to such an extent that the humidity and temperature within the plant community are maintained within a certain range. Due to the occurrence of airflow, carbon dioxide is supplied during the day, and since the plant community is maintained within an appropriate temperature and humidity range, not only can high photosynthesis efficiency be obtained, but diseases can also be suppressed.

[0021] In protected horticulture, in recent years, fumigants have been increasingly used because they can utilize the microclimate by volatilizing into the air inside the greenhouse and can be easily controlled. They are used to control pathogenic bacteria that cause powdery mildew, leaf mold, sooty mold, gray mold, white mold, dry rot, bulb rot, damping-off, black rot, etc., and pests such as aphids, thrips, whiteflies, citrus thrips, southern green thrips, ladybird beetles, small ladybird beetles, apple leafrollers, obliquebanded leafrollers, summer fruit tortrix moths, false Japanese beetles, wireworms, tobacco flea beetles, citrus red mites, etc. Fumigants containing ingredients such as cyflufenamid, triflumizole, mepanipyrim, tetrachloroisophthalonitrile, acetamiprid, bifenthrin, flubendiamide, tebufenpyrad, fenobucarb (BPMC), etc. will be described below. If fumigation is carried out in a mixing cabin for adjusting air, it is possible to disperse the active ingredients within the plant community and obtain a high fumigation effect. Also, since fumigation is carried out by blowing air into the plant community inside the greenhouse, a uniform effect can be obtained.

[0022] [Carbon dioxide concentration] Since photosynthesis requires carbon dioxide and water, controlling the carbon dioxide concentration during the day is important. When plants are cultivated in a greenhouse without carbon dioxide management, carbon dioxide is often consumed by photosynthesis during the day and the concentration can drop below the outdoor carbon dioxide concentration (about 400 ppm). It is said that the net photosynthesis rate increases linearly in the range of 100 - 700 ppm of carbon dioxide, and the photosynthesis amount is the highest at 1000 - 1500 ppm. For example, in the case of tomatoes, there is data showing that when the carbon dioxide concentration increases from 400 ppm to 1000 ppm, the yield increases by 84%. However, even when the carbon dioxide concentration is applied in the range of 700 - 1000 ppm, it leaks out through the gaps in the facility, and the carbon dioxide utilization rate is said to be extremely low. Considering that when there is no air flow without applying carbon dioxide, the carbon dioxide concentration near the back surface in the plant community is below 400 ppm, even if an air flow is constantly generated in the plant community and the carbon dioxide concentration is maintained at about 400 ppm, the yield will increase. Therefore, it is preferable to blow air adjusted to a carbon dioxide concentration of at least 400 ppm or more to maintain the carbon dioxide concentration in the plant community at 400 ppm or more.

[0023] Since the yield increases up to a carbon dioxide concentration of 2000 ppm, it can be set to 2000 ppm in a sealed house where little carbon dioxide leaks to the outside. However, in an unsealed house or when ventilation is required in summer, it is preferable to maintain at least a carbon dioxide concentration comparable to that of the outside air, i.e., 400 ppm or a higher carbon dioxide concentration. Considering the outflow of carbon dioxide to the outside and the photosynthesis amount, it is preferable to set it so that the carbon dioxide concentration can be maintained at 400 ppm to 1000 ppm during the day, more preferably 500 ppm to 900 ppm. The carbon dioxide concentration only needs to be above a certain level around the plants, especially on the underside of the leaves where there are many stomata, and it is not necessary to keep the carbon dioxide concentration constant throughout the house. Furthermore, carbon dioxide application is necessary during the day when photosynthesis occurs, but it is not necessary to apply it at night when the plants do not perform photosynthesis. As shown in the following data, photosynthesis starts with sunrise, and when carbon dioxide application is not carried out, the carbon dioxide concentration in the house decreases rapidly. Therefore, it is preferable to carry out carbon dioxide application at a high concentration of about 900 ppm to 1500 ppm from immediately after sunrise to the morning. Also, in the afternoon, it can be maintained at a concentration that can be maintained at about 600 ppm, which is 200 ppm higher than the atmospheric carbon dioxide concentration of 400 ppm, specifically, it can be applied at about 800 - 900 ppm.

[0024] [Temperature] Temperature management is carried out so that the temperature is suitable for each plant. Also, for some plants, it is not necessary to manage the temperature of the entire house. It is sufficient to manage the temperature near the leaves or the ground temperature, or the temperature can be managed with the air supplied to the base of the plant. Especially for strawberries, it is known that the temperature of the plant base with a growth point called the crown is important and only needs to be within a certain temperature range. Therefore, for strawberries, the temperature can be managed with the air blown to the base of the plant. Alternatively, an electric heating cable can be placed in the cultivation bed for heating. For example, in the case of strawberries, the cultivation bed can be managed to be maintained at 15 - 20°C throughout the year. Also, in summer, the temperature rise can be suppressed by applying cold air with a humidity of 90 - 95% from above the plants, or temperature management can be carried out by watering.

[0025] [Vapor pressure deficit (humidity)] In order to enable plants to perform photosynthesis efficiently, humidity control based on the vapor pressure deficit is important. The vapor pressure deficit is an index indicating the amount required for water vapor to reach saturation at a certain temperature and humidity, and plants are more strongly affected by the vapor pressure deficit than by relative humidity. Therefore, it is desirable to control humidity according to the vapor pressure deficit value.

[0026] During the day, plants open their stomata and transpiration occurs. Plants absorb the water lost by transpiration from the roots and also absorb nutrients in the soil. It is sufficient if the balance between the amount of water absorbed from the roots and the amount of transpiration is maintained. However, if the vapor pressure deficit value is large and water absorption cannot catch up, the plants will close their stomata. As a result, the intake of carbon dioxide from the stomata also stops, and the efficiency of photosynthesis decreases. Even if carbon dioxide is applied, if it is not taken in through the stomata, it will not lead to an increase in the amount of photosynthesis. Therefore, vapor pressure deficit management is important for increasing the amount of photosynthesis. Although the appropriate vapor pressure deficit range varies depending on the plant, it is generally considered good to manage it within 3 - 8 g / m 3 ².

[0027] In addition, humidity is strongly related not only to the efficiency of photosynthesis but also to the occurrence of diseases. In particular, humidity control at night is important for suppressing the occurrence of diseases, and it is managed so that dew does not form. Since the occurrence of diseases increases rapidly when dew forms, the humidity is adjusted to a range of 95% or less.

[0028] Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a prepared air application system for plant cultivation according to this embodiment. Embodiment

[0029] [Prepared air mixing section for plant cultivation] The air mixing section 1 for plant cultivation is equipped with a mixing cabinet 2 that mixes air so that the temperature, humidity, and carbon dioxide concentration are optimized, a carbon dioxide generator 3, a dehumidifier 4, and a humidifier 5. The carbon dioxide generator may use a combustion device such as an FF type oil stove. Along with the supply of carbon dioxide in the combustion gas, when the air temperature is low, warm air can be supplied to keep the temperature of the plant community in the greenhouse above a certain level. Although not shown in the figure, when the air temperature is high, a pipe for blowing warm air is directed outside the mixing cabinet, and the pipe from the high-temperature combustion gas to the mixing cabinet is air-cooled or water-cooled, so that carbon dioxide can be supplied without significantly increasing the temperature in the greenhouse. Currently used carbon dioxide application devices are devices that supply a large amount of carbon dioxide and have a large heat exchange amount, so they cannot be used when the air temperature rises. In contrast, in this embodiment, since only a small amount of carbon dioxide is supplied, cooling by heat exchange is easy, and carbon dioxide can be controlled throughout the cultivation period. Also, here, the carbon dioxide generator 3 and the dehumidifier 4 are arranged outside the mixing cabinet 2, but they can also be arranged inside the mixing cabinet 2.

[0030] The humidity is adjusted by irrigation and ventilation, and is also adjusted to an appropriate range by the dehumidifier 4 and the humidifier 5. The humidifier 5 is connected to a tank for supplying water or a water supply device (not shown) and is constantly supplied with water. Since the appropriate range of saturation deficit / humidity is different during the day and at night, it is appropriately controlled to be within the appropriate range within the day. Any type of humidifier 5 may be used, but it is preferably a mist generator, particularly an ultrasonic mist generator. The mist increases the humidity by generating mist of about 10 - 30 μm. An air mixing fan 6 is provided in the mixing cabinet 2 to mix carbon dioxide, temperature, and humidity within an appropriate range. At night, since plants do not perform photosynthesis, there is no need to apply carbon dioxide. Therefore, temperature and humidity management can be performed while actively ventilating, such as opening the ventilation window of the greenhouse.

[0031] The conditioned air mixed within the mixing chamber 2 is sent into the plant community through the conditioned air supply pipe 8 by the conditioned air supply fan 7. Here, a configuration is shown where the conditioned air is sent into the house through one conditioned air supply pipe 8 from the mixing chamber 2, but a mechanism for sending the conditioned air into the house through a plurality of conditioned air supply pipes may also be used. By supplying conditioned air with a volume that is 0.5 to 10 times, preferably 1 to 8 times, and more preferably 3 to 5 times the volume of the target plant community volume per hour, the air near the plants can be constantly ventilated and exchanged with the conditioned air, and the growth environment of the plants can be controlled. For example, in the case of strawberries, if the community volume is 50 cm in width, 40 cm in height, and 600 m in total row extension of the strawberry community, it is 120 m 3 which means that 60 to 1200 m 3 of conditioned air may be sent into the plant community per hour. Note that taking the community volume as 1, the ventilation rate is defined as how many times the volume of the community is ventilated with conditioned air per hour, and this is called the in-community ventilation rate. For example, for a strawberry community with a community volume of 120 m 3 when it is ventilated with 240 m 3 of conditioned air per hour, it is said that the in-community ventilation rate is 2 times per hour.

[0032] [Air supply system in agricultural house] Figures 2 and 3 show the air supply mechanism of the conditioned air in the house. Figure 2 shows the application of the conditioned air to low-growing plants such as strawberries. The conditioned air supply pipe 8 is branched inside the house and connected to the air supply tube 9 arranged at the base of the plant. The air supply tube 9 can freely crawl over the soil by using a flexible tube such as polyethylene. Here, an air supply tube with a diameter of 5 cm is used, but a tube with a diameter of about 4 to 8 cm can be appropriately selected depending on the plant community volume, the amount of conditioned air supplied, etc. Figure 2(A) shows a perspective view of the air supply tube. On the upper surface of the air supply tube, air supply holes 10 with a diameter of about 0.05 to 1.0 mm are opened, and the conditioned air is supplied to the back of the plant leaves. As described above, the plants have a large number of stomata on the back of the leaves and are performing transpiration and carbon dioxide uptake. Therefore, by supplying the conditioned air as a gentle breeze to the back of the leaves, the photosynthesis efficiency can be increased.

[0033] Figure 2(B) is a top view of the air supply tube 9, showing a form with two air supply holes 10 opened on the upper surface. However, the number and position of the air supply holes can be appropriately set according to the plants to be applied and the spacing between ridges. The conditioning air is supplied from the air supply holes of the air supply tube into the plant community. When it hits the plants, especially the leaves, an air current is generated. The arrows in Figures 2(C) and (D) schematically show the air currents generated when the supplied conditioning air hits the plants. The conditioning air is supplied as a gentle breeze from the air supply holes, and a gentle breeze is always generated around the plants. The plants can maintain appropriate temperature and humidity by the conditioning air, and carbon dioxide will be supplied during the day.

[0034] Also, in strawberries, as described above, it is important for growth to keep the temperature of the crown within a certain range. Although it varies depending on the variety, it is said that when the temperature near the crown is 15°C or lower, the leaf expansion rate decreases, the budding is delayed, and the growth of the plants weakens. It is also known that there are varieties in which flower bud differentiation is delayed when the temperature is 23°C or higher. By arranging the air supply tube 9 as shown in Figures 2(C) and (D) between plants, warm air or cold air can be circulated near the crown, and the temperature can be adjusted to a certain range appropriate for growth. It is only necessary to adjust the temperature around the crown, and there is no need to heat or cool the entire greenhouse, so the temperature can be adjusted appropriately at low cost. Also, in areas where the temperature of the cultivation bed becomes low in winter and effective heating cannot be achieved only by the warm air from the air supply tube, an electric heating cable can be arranged in the cultivation bed to heat it so that the bed temperature becomes 15°C to 18°C.

[0035] An example of application to long-stem plants such as tomatoes is shown in Fig. 3. The adjustable air blowing pipe (not shown) is connected to the blowing tube 9 in the greenhouse, which is the same as the case of applying adjustable air to short-stem plants. Fig. 3(A) shows a perspective view of the blowing tube 9 and the blowing sub-tube 11, and Fig. 3(B) shows a plan view seen from above. The blowing tube 9 is arranged at the base of the plant (see Fig. 3(C) and (D)), and the blowing sub-tube 11 branches vertically from the blowing tube 9. Since the blowing sub-tube 11 is also made of a very light and flexible material such as polyethylene, it stands upright due to the air pressure from the blowing tube 9 and supplies adjustable air laterally to the plant body from the blowing holes 10 that open on both sides (Fig. 3(A) and (C)). The blowing sub-tube 11 is arranged near each plant, and adjustable air is supplied from the blowing holes 10 that open in the blowing sub-tube 11. The adjustable air supplied horizontally from the upright blowing sub-tube 11 (Fig. 3(A), black arrow) changes direction when it hits the plant body (Fig. 3(C)) and can supply adjustable air as a gentle breeze near the plant body of the long-stem plant.

[0036] Furthermore, when the plant height is short, the upper end of the blowing sub-tube can be closed with clips or tape to match the height of the crop and used with a length adjusted according to growth. Since the length of the blowing sub-tube can be easily adjusted vertically according to growth, adjustable air can be applied without waste.

[0037] [Environmental control system using a hanging bed - curtain extension system] For elevated cultivation used for growing strawberries and the like, it is said that the working passage occupies 60 - 70% of the facility area, which is about 20 - 30% less than that of soil cultivation. If the cultivation area can be increased, the yield per unit area will increase. Therefore, a hanging bed system that moves up and down in the greenhouse is adopted to increase the cultivation area.

[0038] Fig. 4(A) shows a perspective view of the suspended bed system 21, and (B) shows the position where the suspended bed has been moved. The suspended bed 22 is suspended by suspension ropes 23 that hang the two ends of the cultivation bed and are wound around a shaft 26 connected to an electric winch 25 on the upper frame beam 24, and is supported in this way. The suspended bed 22 can be moved up and down by the electric winch 25 by winding it up and down along the shaft 26 from the ground surface to above the head according to the work content and the environment inside the greenhouse. Specifically, during work, by moving the suspended bed upward, the passage width and work space are secured (Fig. 4(B), arrow), and the suspended bed for working can be moved to the same height as high - altitude cultivation to perform the work. In high - altitude cultivation, cultivation beds can also be provided in the places that are used as passages, so the cultivation area can be increased and the harvest can be increased. The position of the suspended bed can be controlled according to the daily work, and it is also possible to automatically control the position to a height with good sunlight. Also, when efficient carbon dioxide application or heat preservation is required, the suspended bed can be lowered to the ground surface and covered with the environmental maintenance curtain described later to perform heat preservation or efficient carbon dioxide application.

[0039] The curtain extension system is a system that prevents the dissipation of carbon dioxide and the decrease in temperature by covering the plant community transplanted on the cultivation bed lowered to the ground surface with the environmental maintenance curtain 27. Fig. 5 schematically shows a partial cross - section of the suspended bed - curtain extension system. Three types of curtains are prepared for the environmental maintenance curtain 27: a heat - insulating sheet, a transparent sheet, and a winding frame with no curtain. The upper surface of the plants can be covered with an appropriate curtain by the curtain winder 28. The curtain can cover the plant community with a heat - insulating sheet at night when heat preservation is required and with a transparent curtain during the day when carbon dioxide application is required.

[0040] When working, the environmental maintenance curtain 27 is wound up to just below the frame beam at the top (Fig. 4(B)). When not working, the cultivation bed can be lowered to the ground surface and the curtain can be lowered for use (Fig. 4(A), Fig. 5). By lowering the cultivation bed to the ground surface, the space partitioned by the curtain becomes about 1 / 5 of the entire greenhouse, so the carbon dioxide required for application can be suppressed to about 1 / 5 compared to the case of applying to the entire agricultural greenhouse. Also, when heat retention is required at night, a heat-insulating curtain can be used. Furthermore, by surrounding the outer periphery of the frame with the side wall 29, the plant community can be covered together with the environmental maintenance curtain, so that the dissipation of carbon dioxide can be suppressed and the heat retention effect can be enhanced. Specifically, when heat retention is required in winter, covering with the side wall of the heat-insulating material and the heat-insulating curtain can prevent heat from escaping to the outside air. Also, when heat retention is not required, the side wall can be replaced with a light-transmitting sheet, and covering the plant community together with the transparent environmental maintenance curtain can prevent the dissipation of carbon dioxide.

[0041] The conditioned air for plant cultivation adjusted in the mixing cabin is sent from the duct to the air supply tube 30 and blown from the base of the plant stock. Also, in order to manage the bed temperature in winter, an electric heating cable 31 may be provided on the suspended bed 22. By controlling the soil temperature with the electric heating cable, it is possible to manage the bed temperature at a constant temperature with less energy. Also, by running the irrigation tube 32 along the air supply tube, automatic irrigation can be performed.

[0042] [Plant Cultivation Prepared Air Application System] Next, the plant cultivation prepared air application system will be described. In order to supply conditioned air suitable for plants, a control system that measures the temperature and humidity inside and outside the greenhouse and adjusts the temperature, humidity, and carbon dioxide of the supplied air is required. When cultivating crops in a plurality of agricultural greenhouses, a master unit can be installed in one agricultural greenhouse, the optimal growth conditions such as the temperature and saturation deficit of the cultivated plants can be input, and each greenhouse can be controlled through the slave units.

[0043] FIG. 6 is a diagram schematically showing a prepared air application system 41 for plant cultivation. FIG. 6(A) shows an overview of the prepared air application system 41 for plant cultivation, and FIG. 6(B) schematically shows an adjustment mechanism by controllers 45 (master controller) and 46 (slave controller) of the main unit and the slave units. Adjusted air with appropriately adjusted temperature, humidity, and carbon dioxide concentration is supplied to each house 42 through an adjusted air blowing pipe 8 and a blowing tube 10 by a carbon dioxide supply device 3, a dehumidifier 4, and a humidifier 5 connected to a mixing cabin 2. The temperature, humidity, and carbon dioxide concentration inside the house are measured by a sensor 43 inside the house, and the temperature and humidity of the outside air are measured by a sensor 44 outside the house, and data is sent to the controller of each house. FIG. 6 shows a case where there are a main unit and slave units in the control device, but data of each house is sent to a master controller 45 or a slave controller 46 installed inside the house.

[0044] Optimal conditions such as temperature and saturation deficit regarding the crop to be cultivated, and sunrise and sunset times can be input from an operation terminal 47 to the master controller 45 which is the main unit. Depending on the cultivation conditions input by the master controller 45, not only the house where the master controller is installed but also the houses where slave controllers are installed can be managed. However, since fine conditions such as sunlight exposure differ from house to house, it is desirable to measure the temperature, humidity, carbon dioxide concentration, and the state of the outside air for each house. Data measured by the sensor 43 inside the house is sent to a house internal data management device 48 of the master controller 45 and the slave controller 46, and data measured by the outside sensor is sent to a house external data management device 49. All data is sent to the master controller via a hub 50 (FIG. 6(B)).

[0045] Based on the received data, the master controller 45 calculates how to adjust the temperature, humidity, and carbon dioxide concentration of the conditioned air. A signal is sent to the control device 51 via the hub, and the carbon dioxide supply device 3, dehumidifier 4, and humidifier 5 are driven according to the command, and the air in the mixing chamber is adjusted to an appropriate temperature, humidity, and carbon dioxide concentration. The conditioned air mixed in the mixing chamber 2 is supplied into the plant community in the house through the conditioned air blowing pipe and the blowing tube.

Example

[0046] An example of actually cultivating with a gentle breeze constantly blowing is shown. Strawberries were planted in late September 2019, and the test was conducted from March 30 to May 23 in a vinyl greenhouse with elevated cultivation. Only blowing was carried out all day long through blowing holes with a diameter of 0.6 mm from a blowing tube made of a polyethylene sheet with a diameter of 5 cm, and data was acquired. In the test of Example 1, a test plot was set in the same greenhouse, and since the test was conducted by applying carbon dioxide in the oil combustion gas to the whole greenhouse, only the humidity was adjusted through the blowing tube. Table 1 shows the one-week average data of temperature, saturation deficit, and carbon dioxide concentration with and without blowing. The temperature shows the weekly average of the measured values every 10 minutes from 8:00 to 16:00 during the day and from 19:00 to 5:00 the next day at night. The temperature, humidity, and carbon dioxide concentration other than the outside air temperature are acquired near the leaves within the plant community.

[0047]

Table 1

[0048] It is said that the maximum limit of the daytime air temperature for strawberries is 30 °C, and the minimum limit of the nighttime air temperature is 3 °C. The nighttime air temperature did not fall below the minimum limit, but the daytime air temperature exceeded 30 °C at 30.2 °C in the week of April 6 in the test plot without blowing. Also, the saturation deficit is 3 - 6 g / m 3It is considered good to manage it, but in the test area without ventilation, the values exceeded the optimal range over a period of six weeks on March 30, April 6, 13, 20, 27, and May 11. In contrast, in the test area with ventilation, only on April 6, 13, and 20 did the values exceed the optimal range, but even in that case, the degree of drying is weaker compared to the area without ventilation. Furthermore, regarding the carbon dioxide concentration, in the case without ventilation, the values during the day were lower than 400 ppm, which is the carbon dioxide concentration of the outside air, during all periods. It has become clear that by generating an air current within the plant community by gentle breeze, all of the growth environments of temperature, saturation deficit, and carbon dioxide can be improved.

[0049]

Table 2

[0050] The averages of the yields and sugar contents during the test period were summarized weekly for 30 plants within 3 m in the center of the ventilation area and 30 plants in the area where ventilation was not performed (Table 2). Along with the improvement of the plant growth environment, not only did the yield increase by nearly 20%, but an increase in sugar content was also observed (Table 2). Since an increase in yield of about 20% was confirmed within a limited period, a higher increase in yield is expected over a long period.

Example

[0051] In a vinyl greenhouse where strawberries are cultivated using elevated cultivation in the same manner as in Example 1, for four days from March 30th to April 2nd, 2020, the conditioned air for plant cultivation was adjusted in a mixed cabin, and carbon dioxide was applied from the air supply tube at a concentration of 1400 ppm from 10:00 to 18:00 under the condition of an intra-community ventilation rate of 5 times per hour at the base of the plants, and the carbon dioxide concentrations in the application area and the non-application area were measured (Figure 7). The carbon dioxide in the outside air was 450 - 480 ppm. On March 30th and 31st, it was almost windless and sunny, and the air in the vinyl greenhouse was not ventilated much. In the non-application area, during the day, the carbon dioxide concentration in the community was about 100 ppm lower than that in the outside air because strawberries absorbed carbon dioxide. On the other hand, in the carbon dioxide application area, the concentration was kept high even during the day. In both the application area and the non-application area, at night, the carbon dioxide concentration increased due to the respiration of plants. On April 1st and 2nd, it was windy and cloudy, and overall, the carbon dioxide concentration was close to that of the outside air due to ventilation. In the application area, the carbon dioxide concentration was higher than that in the non-application area, but due to the dissipation of carbon dioxide by the wind, no significant difference was observed between the application area and the non-application area.

Example

[0052] To examine the effect of the curtain extension system, a substantially airtight space covered with a sheet and simulating the curtain extension system was created, and air dehumidified to a carbon dioxide concentration of 1760 ppm and a humidity of 30% was applied from the air supply tube under the same condition of an intra-community ventilation rate of 5 times per hour as above, and the carbon dioxide concentration and humidity were measured. The results are shown in Table 3.

[0053]

Table 3

[0054] From these results, it was found that if carbon dioxide is continuously applied to a space made substantially airtight with a curtain, the carbon dioxide concentration can be maintained high and the humidity can be significantly reduced. Since many diseases such as anthracnose and gray mold occur and reproduce in a high humidity state of 95% or more, it is considered that the disease prevention effect of curtain extension is high.

[0055] As shown above, the environmental control system of the present invention can apply air for plant cultivation with controlled carbon dioxide concentration, humidity, and temperature to the community, and can further maintain a controlled environment by means of a curtain extension system. Also, by using a hanging bed, it is possible to increase the number of cultivated plants per unit area and increase the yield. In the conventional carbon dioxide application system, ventilation is required when the temperature rises in early spring, and there is a long period during which carbon dioxide application cannot be carried out. This system can maintain the carbon dioxide concentration with the environmental maintenance curtain while suppressing the rise in temperature, so that carbon dioxide application can be carried out even when ventilation of the greenhouse is required.

Explanation of Signs

[0056] 1... Prepared air mixing section for plant cultivation, 2... Mixing cabin, 3... Carbon dioxide supply device, 4... Dehumidifier, 5... Humidifier, 6... Air mixing fan, 7... Adjusted air blowing fan, 8... Adjusted air blowing pipe, 9... Blowing tube, 10... Blowing hole, 11... Blowing sub-tube, 21... Hanging bed system, 22... Hanging bed, 23... Hanging rope, 24... Frame beam, 25... Electric winch, 26... Shaft, 27... Environmental maintenance curtain, 28... Curtain winder, 29... Side wall, 30... Blowing tube, 31... Electric heating cable, 32... Irrigation tube, 41... Prepared air application system for plant cultivation, 42... Greenhouse, 43... Greenhouse internal sensor, 44... Greenhouse external sensor, 45... Master controller, 46... Slave controller, 47... Operation terminal, 48... Greenhouse internal data management device, 49... Greenhouse external data management device, 50... Hub, 51... Control device

Claims

1. An environmental control system for an agricultural greenhouse, wherein a hanging bed movable in the vertical direction is provided as a cultivation bed inside the agricultural greenhouse, adjusted air with the carbon dioxide concentration, temperature, and humidity adjusted within a predetermined range is supplied to the back of the leaves of plants, the adjusted air is supplied in a volume 0.5 to 10 times the volume of the plant community volume targeted per hour, and a gentle breeze is sent throughout the plant community to generate an air current and adjust the microenvironment throughout the plant community, and an environment-maintaining curtain movable up and down so as to cover the plant community is provided. An environmental control system characterized by this.

2. The environmental control system according to Claim 1, comprises a mixing cabin for adjusting cultivation air, a carbon dioxide supply device for supplying carbon dioxide, a dehumidifier, and a humidifier, wherein the carbon dioxide concentration, temperature, and humidity are adjusted within a predetermined range in the mixing cabin, and an environmental control system that supplies the adjusted air through a blower tube.

3. The carbon dioxide supply device is a combustion-type carbon dioxide generator, and the environmental control system according to Claim 2, which can be used for supplying carbon dioxide and temperature management of the plant community.

4. The environmental control system according to Claim 2 or 3, wherein the humidifier is a mist generator.

5. At least sensors for measuring temperature and humidity are provided inside and outside the agricultural greenhouse, and the environmental control system according to any one of Claims 1 to 4, which adjusts and supplies the adjusted air mixed by a control device.

6. When cultivating low-growing plants, the blower tube is arranged at the base of the plant, and when cultivating long-stemmed plants, a blower sub-tube is branched vertically from the blower tube and arranged, and a system for applying adjusted air for plant cultivation according to any one of Claims 2 to 5, which supplies adjusted air to each plant.

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