JP2018134104A - Carbon dioxide application system, carbon dioxide control device, carbon dioxide application method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply carbon dioxide more efficiently at lower cost.SOLUTION: The carbon dioxide application control device has a first memory means which memorizes the first set value of carbon dioxide levels, a second memory means that memorizes the second set value which is a level lower than the first set value and which is 400 ppm or more, and a control means that controls a carbon dioxide supplying means for supplying carbon dioxide to a greenhouse having an opening and/or closing window, the control means using the first set value as a level set value when a signal for indicating the opening and/or closing state of a window in the greenhouse indicates that the window is closed, and using the second set level as a level set value when the signal indicates that the window is opened.SELECTED DRAWING: Figure 1

Description

The present invention relates to a carbon dioxide (CO ₂ ) application technique in a greenhouse where crops are grown.

  A technique for applying carbon dioxide in a greenhouse where crops are grown is known. In Patent Document 1, a carbon dioxide concentration sensor is provided outside the greenhouse in order to prevent carbon dioxide from flowing out of the greenhouse when the ventilation window of the greenhouse is open, and carbon dioxide in the greenhouse when the ventilation window is open. A technique for controlling the carbon concentration to be equal to the atmospheric carbon dioxide concentration is disclosed (see abstract).

  There are also producers (farmers) in Japan who have introduced carbon dioxide application systems in greenhouses. However, temperature management is most important in Japan, especially at production sites. Therefore, as a result of temperature control being given priority, there is an application method in which carbon dioxide is applied in the time before the temperature in the greenhouse rises and ventilation begins (2 to 3 hours in the early morning hours when the amount of solar radiation is still low). It was widespread.

JP 2005-65602 A

In the technique described in Patent Document 1, it is necessary to provide a total of two carbon dioxide concentration sensors inside and outside the greenhouse, which has a problem of high costs.
On the other hand, the present invention provides a technique for performing carbon dioxide application more efficiently at a lower cost.

  The present invention includes a first storage unit that stores a first set value of carbon dioxide concentration, a second storage unit that stores a second set value that is lower than the first set value and is 400 ppm or more, When the signal indicating the open / closed state of the window in the greenhouse having the window to be opened / closed indicates that the window is closed, the first set value is set as the concentration set value, and the signal is opened by the signal. If this is the case, a carbon dioxide application control device having a control means for controlling a carbon dioxide supply means for supplying carbon dioxide to the greenhouse using the second set value as a concentration set value is provided.

  The second set value may be 400 ppm or more and 500 ppm or less.

  The first set value may be not less than 600 ppm and not more than 1500 ppm.

  The first set value may be not less than 600 ppm and not more than 1000 ppm.

  The carbon dioxide application control device has time measuring means for measuring time, and the control means, when the time measured by the time measuring means is not within a predetermined range, emits carbon dioxide from the carbon dioxide supply means. It is not necessary to supply carbon.

  The present invention also provides carbon dioxide supply means for supplying carbon dioxide to a greenhouse having a window that opens and closes according to a set temperature, first storage means for storing a first set value of carbon dioxide concentration, and the first setting. Output from a second storage means for storing a second set value having a concentration lower than the value and 400 ppm or more and a detection means for detecting the open / closed state of the window in a greenhouse having a window that opens and closes according to the set temperature. When the signal indicates that the window is closed, the first set value is set as a density set value, and when the signal indicates that the window is open, the second set value is set. And a control means for controlling a carbon dioxide supply means for supplying carbon dioxide to the greenhouse.

  Furthermore, the present invention is a carbon dioxide application method in a greenhouse having a window that opens and closes according to a set temperature and a carbon dioxide supply system that supplies carbon dioxide to the greenhouse. A step of detecting a state, a step of controlling the carbon dioxide supply means using a first set value as a concentration set value when it is detected that the window is closed, and the window being open. A carbon dioxide application method comprising: a step of controlling the carbon dioxide supply means using a second set value that is lower than the first set value and 400 ppm or more as a set concentration value when detected. To do.

  At least one of the first set value and the second set value may be determined based on a Ferker photosynthesis model.

  The set temperature may be determined based on a photosynthesis model of Farker.

  Further, according to the present invention, in the computer having the control means and the storage means, the storage means stores the first set value of the carbon dioxide concentration, and the storage means has a lower concentration than the first set value. Storing a second set value of 400 ppm or more, detecting the open / closed state of the window in a greenhouse having a window that opens and closes according to a set temperature, and closing the window If it is detected, the control means controls the carbon dioxide supply means using the first set value as the concentration set value, and if it is detected that the window is open, the control means And a step of controlling the carbon dioxide supply means using a second set value that is lower than the first set value and 400 ppm or more as the set concentration value. To provide because of the program.

  According to the present invention, more efficient carbon dioxide application can be performed at a lower cost.

The figure which shows the function structure of the carbon dioxide application system 1000 which concerns on one Embodiment. The figure which shows the hardware constitutions of the carbon dioxide application apparatus 2. The flowchart which shows operation | movement of the carbon dioxide control apparatus 250. The figure which shows the relationship between an open / close state and a carbon dioxide concentration, and a control signal. The figure which illustrates the simulation conditions of the photosynthesis speed concerning one example. The figure which illustrates the simulation conditions of the photosynthesis speed concerning one example. The figure which illustrates the simulation result of the photosynthesis speed concerning one example. The figure which illustrates the coefficient used for parameter calculation of a photosynthesis model. The temperature dependence of the photosynthetic optimum temperature is shown. The photograph of the crops cultivated in the applied area and the control area is shown. The carbon dioxide concentration dependence of the photosynthetic rate is shown.

1. Configuration FIG. 1 is a diagram illustrating a functional configuration of a carbon dioxide application system 1000 according to an embodiment. The carbon dioxide application system 1000 includes a greenhouse 1 and a carbon dioxide application device 2. The carbon dioxide application is performed for the purpose of promoting the photosynthesis of plants cultivated in the greenhouse 1 (specifically, promoting the carboxylation reaction of Rubisco). The greenhouse 1 is a greenhouse for growing crops, and includes an openable / closable window 11, a temperature sensor 12, and an open / close detection means 13. The temperature sensor 12 is a sensor that measures the temperature in the greenhouse 1 (hereinafter referred to as “room temperature”). The window 11 is a window that automatically opens and closes according to the room temperature and the set temperature. When the window 11 is open, ventilation between the air in the greenhouse 1 and the outside air is promoted. When the window 11 is closed, ventilation is suppressed. The window 11 opens when the room temperature becomes higher than the set temperature, and closes when the room temperature becomes lower than the set temperature. The open / close detection means 13 detects the open / closed state (open or closed) of the window 11 and outputs a signal indicating the detection result (hereinafter referred to as “open / closed state signal”). As the opening / closing detection means 13, any type such as a magnetic sensor type or a mechanical type may be used.

  The carbon dioxide application device 2 is a device for applying carbon dioxide in the greenhouse 1. The carbon dioxide application device 2 includes a carbon dioxide supply unit 21, a storage unit 22, a concentration measurement unit 23, a control unit 24, and a time measuring unit 25. The carbon dioxide supply means 21 supplies carbon dioxide into the greenhouse 1. The memory | storage means 22 memorize | stores the parameter regarding the density | concentration setting value of the carbon dioxide at the time of applying a carbon dioxide. In this example, the storage means 22 sets parameters relating to two different density setting values (hereinafter referred to as “first setting value” and “second setting value”, where the second setting value is lower than the first setting value). Remember. In this example, the parameter regarding the concentration setting value includes information for specifying the upper limit value and the lower limit value of the carbon dioxide concentration. The concentration measuring means 23 measures the carbon dioxide concentration in the greenhouse 1. The control unit 24 controls the carbon dioxide supply unit 21 based on the parameters stored in the storage unit 22 and the carbon dioxide concentration measured by the concentration measurement unit 23. In this example, when the open / close state signal indicates that the window 11 is closed, the control unit 24 sets the first set value as the density set value. On the other hand, when the open / close state signal indicates that the window 11 is open, the second set value is set as the density set value. The time measuring means 25 measures the current time.

  FIG. 2 is a diagram illustrating a hardware configuration of the carbon dioxide application device 2. The carbon dioxide application device 2 includes a carbon dioxide generation device 200, a carbon dioxide concentration sensor 230, a carbon dioxide control device 250, a fan 260, and a duct 270. The carbon dioxide generator 200 is a kerosene combustion type carbon dioxide generator. The carbon dioxide generator 200 performs ignition (on) and extinguishing (off) in accordance with a control signal from the outside. The carbon dioxide concentration sensor 230 measures the concentration of carbon dioxide and outputs a signal indicating the measurement result (hereinafter referred to as a carbon dioxide concentration signal). The carbon dioxide concentration sensor 230 is installed in the vicinity of the crop P to be cultivated in the greenhouse 1.

The carbon dioxide control device 250 is a device that controls the carbon dioxide generation device 200 and includes, for example, a program relay. The program relay includes a processor, a memory, and a timer. In this example, the carbon dioxide control device 250 outputs a signal for controlling the carbon dioxide generation device 200 based on the open / close state signal and the carbon dioxide concentration signal. The memory of the carbon dioxide controller 250 stores two concentration setting values, a first setting value and a second setting value, and a concentration width as parameters relating to the concentration setting value. The carbon dioxide controller 250 uses the first set value when the open / close state signal indicates that the window 11 is closed, and when the open / close state signal indicates that the window 11 is open. The second set value is used. The carbon dioxide control device 250 outputs a signal for turning off the carbon dioxide generator 200 when the carbon dioxide concentration indicated by the carbon dioxide concentration signal exceeds the upper limit value, and the carbon dioxide concentration falls below the lower limit value. When it is, a signal for turning on the carbon dioxide generator 200 is output. In addition, the program relay can output a signal for turning on the carbon dioxide generation device 200 only in a specific time period using a timer. In this case, the memory of the carbon dioxide control device 250 stores parameters (application start time and application end time) that specify the application time zone.

  The carbon dioxide control device 250 has a user interface (for example, a display device and a keypad) for inputting or changing a parameter related to the concentration setting value. The user can enter or change parameters related to the density setting value via this interface.

  The fan 260 and the duct 270 are mechanisms for delivering the carbon dioxide generated by the carbon dioxide generator 200 to the vicinity of the crop to be cultivated. In this example, the fan 260 is interlocked with the carbon dioxide generator 200, and the fan rotates only when the carbon dioxide generator 200 generates carbon dioxide.

  The carbon dioxide generator 200 is an example of the carbon dioxide supply means 21. The carbon dioxide concentration sensor 230 is an example of the concentration measuring unit 23. The carbon dioxide control device 250 is an example of the storage unit 22, the control unit 24, and the time measuring unit 25.

2. Operation FIG. 3 is a flowchart showing the operation of the carbon dioxide control device 250. The flow in FIG. 3 is started when the power source of the carbon dioxide control device 250 is turned on, for example. In step S100, carbon dioxide control device 250 determines whether the current time is within a predetermined application time zone. When it is determined that the current time is within the application time zone (step S100: YES), the carbon dioxide control device 250 moves the process to step S101. When it is determined that the current time is not within the application time zone (step S100: NO), the carbon dioxide control device 250 outputs a signal for turning off the carbon dioxide generation device 200 (step S106).

  In step S101, the carbon dioxide control device 250 acquires the open / closed state. The open / close state is indicated by an open / close state signal. In step S102, the carbon dioxide control device 250 determines whether the window 11 is closed. When it is determined that the window 11 is closed (step S102: YES), the carbon dioxide control device 250 determines to use the first set value as the concentration set value (step S103). When it is determined that the window 11 is open (step S102: NO), the carbon dioxide control device 250 determines to use the second set value as the concentration set value (step S104).

  In step S105, the carbon dioxide control device 250 determines whether the carbon dioxide concentration Ph indicated by the carbon dioxide concentration signal exceeds the upper limit value of the concentration. When it is determined that the carbon dioxide concentration Ph exceeds the upper limit value of the concentration (step S105: YES), the carbon dioxide control device 250 outputs a signal for turning off the carbon dioxide generation device 200 (step S106). When it is determined that the carbon dioxide concentration Ph does not exceed the upper limit value of the concentration (step S105: NO), the carbon dioxide control device 250 moves the process to step S107.

In step S107, the carbon dioxide control device 250 determines whether the carbon dioxide concentration Ph indicated by the carbon dioxide concentration signal is below the lower limit value of the concentration. When it is determined that the carbon dioxide concentration Ph is below the lower limit value of the concentration (step S107: YES), the carbon dioxide control device 250 outputs a signal for turning on the carbon dioxide generation device 200 (step S108). When it is determined that the carbon dioxide concentration Ph is not below the lower limit value of the concentration (step S107: NO), the carbon dioxide control device 250 is
The state of 0 is maintained (step S109). That is, if the signal for turning on the carbon dioxide generation device 200 has been output until then, the carbon dioxide control device 250 continues to output the signal for turning on the carbon dioxide generation device 200 and turns off the carbon dioxide generation device 200 until then. If the signal to be output has been output, a signal to turn off the carbon dioxide generator 200 is continuously output. Note that the flow of FIG. 3 is repeatedly executed at a predetermined timing (for example, periodically).

  FIG. 4 is a diagram illustrating the relationship between the open / close state signal and the carbon dioxide concentration signal, and the control signal output from the carbon dioxide control device 250. In this example, a density setting value is used as the upper limit value of the density, and a value obtained by subtracting the density width ΔP from the density setting value is used as the lower limit value. When the open / close state signal indicates that the window 11 is closed and the carbon dioxide concentration Ph indicated by the carbon dioxide concentration signal satisfies Ph> Pth1, the carbon dioxide control device 250 A control signal for turning off the generator 200 is output. Pth1 represents the first set value. In the case where the open / close state signal indicates that the window 11 is closed, when the carbon dioxide concentration Ph satisfies Ph <(Pth1−ΔP), the carbon dioxide control device 250 performs the carbon dioxide generation device 200. A control signal for turning on is output. When the open / close state signal indicates that the window 11 is open and the carbon dioxide concentration Ph indicated by the carbon dioxide concentration signal satisfies Ph> Pth2, the carbon dioxide control device 250 A control signal for turning off the generator 200 is output. Pth2 represents the second set value. In the case where the open / close state signal indicates that the window 11 is open, when the carbon dioxide concentration Ph satisfies Ph <(Pth2-ΔP), the carbon dioxide control device 250 performs the carbon dioxide generation device 200. A control signal for turning on is output. The density range for the first set value and the density range for the second set value may be different from each other.

3. Example 3-1. Simulation Next, an application example of the present invention will be described. First, the estimation result of the photosynthetic rate by simulation will be described. 5 and 6 are diagrams showing simulation conditions. FIG. 7 is a diagram illustrating a simulation result of the photosynthetic rate in one embodiment. The simulation was performed under the following conditions. The following comparative example corresponds to an application method (hereinafter referred to as “conventional application”) widely adopted by producers currently applying carbon dioxide. In this example, since there is a possibility that the temperature in the greenhouse rises from around 9 am and the window opens, it is applied only for 2 hours from 6 am with timer control.
Photosynthesis model: Improved Farquhar model Crop: Eustoma grandiflorum (Raf.) Shinn
Greenhouse temperature: Based on actual measurements on January 13, 2012 in a certain Eustoma greenhouse (FIG. 5)
Solar radiation: Same as above (Figure 5)
Carbon dioxide concentration in the greenhouse: Same as above (Figure 6)
Window opening / closing temperature: 25 ° C
(Example)
Pth1: 1000ppm
Pth2: 400 ppm
Application hours: From 8:00 am to 4:00 pm (comparative example)
Carbon dioxide is applied only for 2 hours from 6 am The carbon dioxide concentration at the time of application is 1000 ppm

It supplements about the photosynthesis model used in the present Example. The photosynthesis model used here is the photosynthesis model proposed by Farker et al. (Farquhar GD, von Caemmerer S, Berry JA. 1980. A biochmical model of photosynthesis CO ₂ assimilation in leaves of C3 species. Planta 149: 78-90) (Sharkey TD 1985 Photosynthesis in inmtact leaves of C3 plants, Phisics, phisiology and rate limitations. Botanical Review 51: 53-105). Hereinafter, this improved model of a furker is simply referred to as a furker model.

In the Farker model, the photosynthesis speed A is expressed by the following equation (1).
Here, Av is the photosynthesis rate when the Rubisco carboxylation reaction is rate-limiting, and is represented by the following formula (2).
Aj is the photosynthesis rate at the time of electron transfer rate-determining and is expressed by the following equation (3).
Ap is the photosynthesis rate at the time of phosphoric acid control, and is expressed by the following formula (4).
R is breathing.

  For the meaning and calculation method of each parameter in equations (2) to (4), see Kim et al. (Kim SH, Lieth JH. 2003. A coupled model of photosynthesis, stomatal conductance and transpiration for a rose leaf (Rosa hybrida L .).)It is described in. Some parameters can be found in other literature such as De Pury DGG, Farquuhar GD, 1997. Simple scaling of photosynthesis from leaves to canopies without the errors of big-leaf models. Plant, Cell and Environment. 20: 537-557).

The inventor of the present case studies the temperature dependence of photosynthetic characteristics of eustoma and roses, and from the measured values of the photosynthetic rate under various temperature conditions, the maximum rate Vcmax of Rubsco carboxylation reaction, the maximum rate of electron transfer Jmax, The temperature dependence of Rd, a constant for converting atmospheric carbon dioxide concentration into leaf carbon dioxide concentration (-1 / k / RH), and phosphoric acid utilization rate Pu was clarified. In this example, Ci = (1-1 / k / RH) Ca was used as a conversion formula between the atmospheric carbon dioxide partial pressure Ca and the leaf carbon dioxide partial pressure Ci. The inventor of this case approximates the temperature dependence of these parameters with a polynomial of up to 4th order, and clearly shows that the photosynthetic rate calculated using the parameters calculated with these polynomials is in good agreement with the measured value. did. As an example, FIG. 8 shows coefficient values indicating temperature dependence of these parameters in Eustoma grandiflorum. In this example, polynomial approximation is used for Vcmax, Jmax, Rd, and -1 / k / RH, and exponential function approximation is used for Pu. Coefficient ai
Indicates the coefficient of the i-th order term.

  The parameters of the furker model are not limited to this. You may combine a furker model with another model. Further, the temperature dependence of the parameters is not limited to that using the polynomial described above. A so-called Arrhenius equation or a modified Arrhenius equation may be used. For crops for which the parameters of the Farker model are not known, the values of the crops for which the parameters are known may be substituted.

  Refer to FIG. 7 again. As a result of the simulation, the integrated photosynthesis amount per day increased by 16% in the example compared with the comparative example. Thus, according to the Example, it turns out that a carbon dioxide application is performed more effectively compared with the conventional application method.

The customary application widely used in production sites is that carbon dioxide is applied only in the early morning (for example, from 6:00 am to 8:00 am), and carbon dioxide is not applied in other time zones. Such application methods are described in several documents. For example, Takashi Osuka, 2003, Carbon Dioxide Control, p. 170-177, edited by Japan Facility Horticultural Association, 5th edition facility gardening handbook, Japan Facility Horticultural Association, Japan, ventilated 30 minutes after sunrise in cucumber cultivation It is described that carbon dioxide application is performed for 2 to 3 hours before starting. In addition, the Agriculture and Mountain Fishing Village Cultural Association, Agricultural Technology University, Hanatsubaki Edition 3, Environmental Elements and Control, Control of Carbon Dioxide, p.536, Carnation Cultivation, carbon dioxide application for 30 to 3 hours before sunrise It is described to do. In addition, the Agriculture and Mountain Fishing Village Cultural Association, Agricultural Technology University, Hanatsubaki Edition 3, Environmental Elements and Control, Control of Carbon Dioxide, p. It is described that carbon dioxide is applied on a cloudy day. In addition, the Agriculture and Mountain Fishing Village Cultural Association, the Agricultural Technology University, Hanatsubaki Edition 3, Environmental Elements and Control, Control of Carbon Dioxide, p. It is described that areas with a lot of sunshine are suitable for institutional horticulture, but not suitable for carbon dioxide application. However, according to the present invention, it is possible to apply carbon dioxide even in areas with a lot of sunlight. In addition, although FIG. 3 on the same page of this document describes that Shizuoka with a lot of sunshine is unsuitable for carbon dioxide application, the present invention is also effective in cultivation in Shizuoka as described later.

  On the other hand, the inventor of the present case has considered a method for performing carbon dioxide application under strong light under the idea that carbon dioxide application exhibits its effect under strong light rather than under low light. First of all, carbon dioxide is applied even when the ventilation window is open. However, if the concentration of carbon dioxide is too high when the ventilation window is open, it is useless, so it is a two-stage dioxide process, with a high concentration when the ventilation window is closed and a low concentration when the ventilation window is open. Apply carbon. Secondly, the temperature at which the ventilation window opens is set higher than before in order to make the time for applying carbon dioxide at a high concentration as long as possible. The photosynthesis rate depends on the temperature, and there exists a temperature (photosynthesis appropriate temperature) at which the photosynthesis rate is maximized. It is known that the optimum photosynthetic temperature shifts to a higher temperature side when the carbon dioxide concentration increases under strong light conditions (see, for example, FIG. 9). That is, under a high carbon dioxide concentration condition, the temperature at which the ventilation window opens can be set higher than the conventional temperature from the viewpoint of photosynthesis. On the other hand, if the temperature at which the ventilation window is opened is too high, the quality of the crop may be affected. The temperature at which the ventilation window opens is determined in consideration of these circumstances comprehensively.

  In the example of FIG. 7, the window opening / closing temperature is 25 ° C. in both the example and the comparative example, but the window opening / closing temperature in the example can be set to a higher temperature according to the above concept. In that case, since the photosynthesis speed is expected to increase further, the difference in the photosynthesis amount between the example and the comparative example is expected to be further improved from the 16% increase described in FIG. Thus, according to this invention, compared with a comparative example, more effective carbon dioxide application can be performed.

3-2. Demonstration test in a field Next, a demonstration experiment in a field was performed under the following conditions.
(Test conditions)
Farm: Two greenhouses in Shizuoka Prefecture x 2 Farms Area: Approximately 700m ² per building
Variety: Eustoma (Piccorosa Snow)
Number of planted plants: about 1300 Planted time: Mid-October 2012 Shipment: February-March 2013

Under the above conditions, cultivation was carried out with one building in the greenhouse as an application zone (Example) and one building as a control zone (Comparative Example). In the application area, carbon dioxide was applied, and in the control area, carbon dioxide was not applied. More detailed application conditions are as follows.
(Application area)
Carbon dioxide application time: 8: 00-15: 00
Carbon dioxide application start: December Ventilation temperature: 30 ° C
Carbon dioxide concentration: 430ppm (when window is open) / 800ppm (when window is closed)
(Control zone)
Carbon dioxide application: None Same conditions as application area except above

  FIG. 10 shows photographs of crops cultivated in the application area and the control area. On the right are crops grown in the application area and on the left in the control area. It can be seen that the crops cultivated in the application area have more florets and flowering. In the following, this point will be explained using more quantitative data.

Table 1 shows the shipping rate in the application area and the control area. Some of the planted plants do not have enough quality to be shipped to the market due to lack of flowering or insufficient plant height. Table 1 shows the proportion of the planted plants that could be shipped. The shipping rate in the control zone was 79.6%, while the shipping rate in the application zone was 98.9%, which is 9 points higher than the control zone.

Table 2 shows the breakdown of the shipped flower grades. The shipped flowers are classified into one of three grades of excellent, excellent, and good according to a predetermined standard. Here, those with flowering numbers of 3 or more and cocoon numbers of 2 or more were excellent, and those that were not classified excellently were those that were flowering numbers of 2 or more and cocoon numbers of 1 or more, and those that were not classified as excellent or excellent ( Flowering number 1 or more) was classified as good. In Table 2, “class” indicates a classification based on the stem length [cm].

  The percentage of excellent products in the control ward was 43%, while the percentage of excellent products in the application ward was 69%, which was 25 points higher. Thus, in the application area, it was found that not only the shipping rate is high but also the excellent product rate is high, and by applying the present invention, high quality products can be shipped at a high rate.

3-3. About the carbon dioxide concentration The influence of the carbon dioxide concentration at the time of carbon dioxide application was evaluated by measuring the photosynthetic rate under different carbon dioxide concentrations. The measurement was performed during the daytime in the field where the above demonstration test was performed. It was Eustoma (Voyage White) used for the measurement. The measurement conditions are as follows.
Carbon dioxide concentration: 350 ppm (control group)
380ppm, 410ppm, 430ppm (application area)
Leaf temperature: about 29 ° C
Light intensity: PPFD 1200 μmol ⁻² s ⁻¹
(Red LED light source including 10% blue LED)
Humidity: 60%
For the measurement of the photosynthetic rate, a photosynthesis measuring device LI-6400 manufactured by LI-COR was used. The photosynthetic rate in the control plot was measured at the same concentration as the carbon dioxide concentration in the greenhouse in the control plot while the ventilation window was open.

  FIG. 11 shows the carbon dioxide concentration dependence of the photosynthesis rate. In the application group, when the carbon dioxide concentration was 380 ppm (corresponding to the atmospheric carbon dioxide partial pressure), there was no significant difference from the photosynthesis rate in the control group. This is considered to be caused by the fact that the carbon dioxide concentration in the control group is 350 ppm and the difference from the atmospheric carbon dioxide partial pressure is small. On the other hand, when the carbon dioxide concentration was set to 410 ppm or 430 ppm higher than the atmospheric carbon dioxide partial pressure, the photosynthetic rate was greatly improved. Thus, more effective carbon dioxide application can be performed by performing carbon dioxide application at a carbon dioxide concentration higher than the atmospheric carbon dioxide partial pressure.

The carbon dioxide concentration when the window is open may be higher than the atmospheric level (for example, 400 ppm or more), but specifically, for example, may be determined as follows. First, as the temperature condition, a set temperature at which the ventilation window is opened is assumed. As light conditions, strong light (for example, 1000 μmolm ⁻² s ⁻¹ PPFD) is assumed. Under these temperature conditions and light conditions, the carbon dioxide concentration (second set value) on the low concentration side is a predetermined ratio (for example, 5%, 10%, etc.) or more as compared with the case of no carbon dioxide application, Carbon dioxide conditions that increase the rate of photosynthesis are determined using the Farker model. For the carbon dioxide concentration (first set value) on the high concentration side, the carbon dioxide concentration (about 1000 ppm as an example) at which the photosynthetic rate is saturated under the above temperature condition and light condition is determined using the Farker model. As the carbon dioxide concentration at which the photosynthesis rate is saturated, the rate of change in the photosynthesis rate is a predetermined threshold (for example, 10%, 5%, 1%, etc.) in the photosynthesis rate-carbon dioxide concentration characteristic (A-Ci curve). ) Use a carbon dioxide concentration below. It should be noted that the carbon dioxide concentration may be determined using an actual value of photosynthesis rate instead of prediction of photosynthesis rate using the Farker model.

  Note that Patent Document 1 eliminates the waste of carbon dioxide application when the ventilation window is opened (see paragraph 0012). Specifically, the flow of carbon dioxide out of the greenhouse is almost zero. It is aimed (paragraph 0018). Therefore, the control of the carbon dioxide concentration higher than the atmospheric level when the window is open is inconsistent with the purpose of the cited document 1 as in the present invention, and the present invention is conceived based on the cited document 1. Is difficult. Furthermore, the technique of Patent Document 1 requires a total of two carbon dioxide concentration sensors inside and outside the greenhouse and is expensive, but in the present invention, it is not necessary to provide a carbon dioxide concentration sensor outdoors, and a low-cost system can be provided. Can be built.

4). Modifications The present invention is not limited to the above-described embodiments, and various modifications can be made. Hereinafter, some modifications will be described. Two or more of the following modifications may be used in combination.

The first set value Pth1 and the second set value Pth2 are not limited to those described in the embodiments. For the first set value Pth1, a carbon dioxide concentration that provides a desired photosynthesis rate may be used by using a photosynthesis model such as a Farker model or by another method. As the first set value Pth1 [ppm], for example, a value in the following range is used.
600 ≦ Pth1 ≦ 1500 (5)
For the first set value Pth1, the range of the following equation (6) is more preferable.
600 ≦ Pth1 ≦ 1000 (6)
As the second set value Pth2 [ppm], for example, a value in the following range is used.
400 ≦ Pth2 ≦ 500 (7)
Note that the second set value Pth2 may be higher than the atmospheric carbon dioxide concentration even if it is outside the range of the equation (7). Of the parameters relating to carbon dioxide application, at least one of the first set value, the second set value, and the window opening / closing temperature may be determined using a Farker model.

  The relationship between the threshold value for turning carbon dioxide application on or off and the set value of the carbon dioxide concentration is not limited to that described in the embodiment. For example, centering on the set value of the carbon dioxide concentration, the set value plus concentration range may be the upper limit value (threshold value for turning off), and the set value minus concentration range may be the lower limit value (threshold value for turning on). Or you may set an upper limit and a lower limit, respectively. In addition, a control method other than that described in the embodiment, for example, PI control or PID control may be used for on / off of carbon dioxide application.

  The hardware configuration of the carbon dioxide control device 250 is not limited to that exemplified in the embodiment. For example, instead of (or in addition to) the kerosene combustion type exemplified in the embodiment, the carbon dioxide supply means 21 uses a gas cylinder, uses heating exhaust gas, or uses industrial exhaust gas. It may be adopted. When a gas cylinder or the like other than the kerosene combustion type is used, the carbon dioxide application device 2 may not include the fan 260 and the duct 270. In addition, a part of the functional configuration described in FIG. 1 may be deleted. For example, the time measuring means 25 may be omitted. Moreover, the function as the carbon dioxide supply means 21 and the function as the control means 24 may be provided by a single device.

  Although the Example demonstrated the example which applied this invention to cultivation of Eustoma grandiflorum, the crop used as the object of this invention is not limited to Eustoma grandiflorum. The present invention is applicable to all C3 plants. The photosynthetic model described in the embodiment is for a single leaf, but a model that considers a community may be used based on the Farker model.

  Some functions of the carbon dioxide application device 2 (for example, the storage unit 22, the control unit 24, and the time measuring unit 25) may be implemented as computer software. For example, the algorithm described in the embodiment may be used in control software in a so-called ubiquitous control system (a remote control system using a computer network).

DESCRIPTION OF SYMBOLS 1 ... Greenhouse, 2 ... Carbon dioxide application apparatus, 11 ... Window, 12 ... Temperature sensor, 13 ... Opening / closing detection means, 21 ... Carbon dioxide supply means, 22 ... Storage means, 23 ... Concentration measurement means, 24 ... Control means, 25 ... Time measuring means, 200 ... carbon dioxide generator, 230 ... carbon dioxide concentration sensor, 250 ... carbon dioxide control device, 260 ... fan, 270 ... duct, 1000 ... carbon dioxide application system

Claims (9)

A carbon dioxide concentration sensor installed near a plant cultivated in the greenhouse having a window that opens and closes,
A carbon dioxide generator for generating carbon dioxide to be supplied into the greenhouse;
A carbon dioxide control device that controls the carbon dioxide generator based on the carbon dioxide concentration measured by the carbon dioxide concentration sensor,
The carbon dioxide control device includes:
First storage means for storing a first set value of carbon dioxide concentration;
Second storage means for storing a second set value having a concentration lower than that of the first set value and not less than 400 ppm;
When the window is closed in the greenhouse, the first set value is a concentration set value, and when the window is open, the second set value is a concentration set value, And a carbon dioxide application system having a control means for controlling. 2. The carbon dioxide application system according to claim 1, further comprising: a set value determining unit that determines at least one of the first set value and the second set value based on a predetermined photosynthesis model and a given temperature environment and light condition. The carbon dioxide application system according to claim 1 or 2, wherein the second set value is 400 ppm or more and 500 ppm or less. The carbon dioxide application system according to any one of claims 1 to 3, wherein the first set value is not less than 600 ppm and not more than 1500 ppm. The carbon dioxide application system according to claim 4, wherein the first set value is 600 ppm or more and 1000 ppm or less. Having a time measuring means for measuring time,
The control means does not supply carbon dioxide from the carbon dioxide generating device when the time measured by the time measuring means is not within a predetermined range. The carbon dioxide application system according to Item. First storage means for storing a first set value of carbon dioxide concentration;
Second storage means for storing a second set value having a concentration lower than that of the first set value and not less than 400 ppm;
When the window is closed in a greenhouse having a window that opens and closes, the first set value is set as a concentration set value, and when the window is open, the second set value is set as a concentration set value. Means for controlling a carbon dioxide generator for generating carbon dioxide to be supplied into the greenhouse based on a carbon dioxide concentration measured by a carbon dioxide concentration sensor installed near the plant to be cultivated than the window And a carbon dioxide control device. A carbon dioxide concentration sensor installed near a plant cultivated in the greenhouse having a window that opens and closes, a carbon dioxide generator for generating carbon dioxide to be supplied into the greenhouse, and the carbon dioxide concentration sensor. In a carbon dioxide application system having a carbon dioxide controller that controls the carbon dioxide generator based on the measured carbon dioxide concentration,
The carbon dioxide control device storing a first set value of carbon dioxide concentration;
The carbon dioxide control device stores a second set value having a concentration lower than the first set value and not less than 400 ppm;
When the window is closed in the greenhouse, the carbon dioxide control device sets the first set value as a concentration set value, and when the window is open, sets the second set value as a concentration set value. And a step of controlling the carbon dioxide generator. A carbon dioxide concentration sensor installed near a plant cultivated in the greenhouse having a window that opens and closes, a carbon dioxide generator for generating carbon dioxide to be supplied into the greenhouse, and the carbon dioxide concentration sensor. A computer used as the carbon dioxide control device in a carbon dioxide application system having a carbon dioxide control device that controls the carbon dioxide generation device based on the measured carbon dioxide concentration,
The carbon dioxide control device storing a first set value of carbon dioxide concentration;
The carbon dioxide control device stores a second set value having a concentration lower than the first set value and not less than 400 ppm;
When the window is closed in the greenhouse, the carbon dioxide control device sets the first set value as a concentration set value, and when the window is open, sets the second set value as a concentration set value. And a step for controlling the carbon dioxide generator.