Leaf temperature sensor, plant body temperature observation device for plants under coating material, leaf temperature difference observation method, and leaf temperature variation observation method

Abstract

To enable stable long-term leaf temperature measurement by suppressing the influence of weather and an external environment.SOLUTION: A leaf temperature sensor comprises: a thermocouple consisting of two different metals and having first and second contact points where the two metals are connected, the first contact point being disposed inside a leaf of a plant model and the second contact point being disposed on the outside of the leaf; and a voltmeter for measuring a voltage generated by the thermocouple. The plant model is formed to have a leaf with a thickness and emissivity similar to those of an actual leaf.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a leaf temperature sensor, a device for observing plant body temperature under covering materials, a method for observing leaf temperature and air temperature difference, and a method for observing leaf temperature change, and more particularly to a leaf temperature sensor, a device for observing plant body temperature under covering materials, a method for observing leaf temperature and air temperature difference, and a method for observing leaf temperature change that can suppress the influence of weather and the external environment and stably measure leaf temperature under different covering materials for a long period of time. [Background technology]

[0002] During winter nights, the temperature of plants drops below the air temperature due to radiant heat exchange inside and outside the greenhouse. A drop in the plant's accumulated temperature has a negative impact on leaf development and fruit maturation speed. Therefore, it is ideal to prevent the plant's temperature from dropping as much as possible. Plant temperature can be measured by leaf temperature.

[0003] For example, in greenhouses during winter nights, in order to prevent a drop in plant body temperature due to radiative cooling, it is necessary to heat the greenhouse so that leaf temperature approaches a target temperature, and a drop in leaf temperature leads to an increase in energy consumption. The degree of drop in leaf temperature varies depending on the type of covering material used (longwave radiation characteristics). For this reason, the difference between air temperature and leaf temperature (ΔTleaf) can be one index for evaluating the performance of covering materials. For example, it can be determined that the smaller ΔTleaf is, the higher the heat retention performance of the covering material.

[0004] In addition, if ΔTleaf for each covering material is known, producers can determine the heating setting temperature to bring the leaf temperature to the target temperature, allowing them to control crop growth more precisely. Therefore, ΔTleaf for each covering material is an indicator for producers when selecting covering materials, and is necessary for more precise control of crop growth.

[0005] Furthermore, a technique for measuring the coefficient of heat transmission has been proposed to evaluate the thermal insulation performance of covering materials (see, for example, Patent Document 1, Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3). Furthermore, research has been conducted on the relationship between leaf temperature and outdoor wind speed (see, for example, Non-Patent Document 4). Research has also been conducted on the relationship between geothermal energy and leaf temperature due to differences in the radiation characteristics of films. Furthermore, a technique for measuring leaf temperature using a simple radiometer has been proposed (see, for example, Non-Patent Document 6). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 57-146140 [Non-patent literature]

[0007] [Non-Patent Document 1] Mihara, Y. and Hayashi, M. (1979) Studies on Greenhouses and Thermal Insulation (1), Journal of Agricultural Meteorology, 35(1), 13-19. [Non-Patent Document 2] M. Hayashi, M. Ohara, M. Shimizu, and T. Yamamoto (2011). Development of a measuring device for the thermal transmittance of greenhouse covering materials. Agricultural Facilities, 41(4), 163-169. [Non-Patent Document 3] Ariga, H.; Oda, K.; Nishimura, Y.; Fukumoto, Y. (2015) A simple method for evaluating the thermal insulation properties of agricultural covering materials using a thermal conductivity measuring device. Plant Environmental Engineering, 27 (1), 14-23. [Non-Patent Document 4] Igarashi, D. and Okada, M. (1989). Iwate Prefectural Agricultural Research Center. Relationship between air temperature and leaf temperature under bed cover for preventing frost damage in cabbage and outdoor wind speed. Kanagawa Prefectural Horticultural Experiment Station Research Report, 38, 15-19. [Non-Patent Document 5] Hamasaki T, Okada M (1996) An analysis of crop growth under plastic films with different long-wave radiation transmittance. Acta Horticulturae, 440, 171-174. [Non-Patent Document 6] Kondo Junsei's nighttime radiometer and leaf surface thermometer are now commercially available https: / / www.asahi-net.or.jp / ~rk7j-kndu / kenkyu / ke178.htm Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the techniques of Patent Document 1, Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3, the heat transfer coefficient is calculated to evaluate the thermal insulation performance of covering materials. Since the heat transfer coefficient is a heat transfer coefficient that includes heat conduction and heat transfer in addition to radiation heat transfer, it is not possible to estimate ΔTleaf, which varies due to radiation heat exchange between the leaf and the sky, even if the heat transfer coefficient is used.

[0009] In addition, since the techniques of Non-Patent Documents 4 and 5 are premised on outdoor measurements, in order to observe how leaf temperature changes when different covering materials are used, for example, it is necessary to simultaneously create a greenhouse using multiple covering materials and measure leaf temperatures, in order to compare the heat retention performance of covering materials.

[0010] Furthermore, since leaf temperature affects the growth of crops, it is desirable to continue measuring it throughout the cultivation period. Conventionally, leaf temperature was measured by attaching a thermocouple to the leaf, but it was difficult to stably measure leaf temperature for a long period of time due to the plant's sleep behavior and growth. In addition, Non-Patent Document 6 does not take into account the thermal properties of the leaf, and it may not be possible to measure a temperature equivalent to the actual leaf temperature.

[0011] One aspect of the present invention has been made in consideration of the above-mentioned problems, and one example of its objective is to suppress the effects of weather and the external environment and enable stable measurement of leaf temperature over a long period of time. [Means for solving the problem]

[0012] In order to solve the above problems, a leaf temperature sensor according to one embodiment of the present invention comprises a thermocouple made of two different metals, the thermocouple having a first junction and a second junction where the two metals are connected, the first junction being arranged inside a leaf of a plant model and the second junction being arranged outside the leaf, and a voltage meter that measures the voltage generated by the thermocouple, and the plant model is formed so that the thickness and emissivity of the leaf are approximately the same as those of a real leaf.

[0013] A leaf temperature sensor according to another aspect of the present invention includes a temperature measurement point disposed inside a leaf of a plant model, and a temperature detector for measuring the temperature at the temperature measurement point, and the plant model is formed so that the thickness and emissivity of the leaf are approximately the same as those of a real leaf. Any type of temperature sensor can be used.

[0014] In one embodiment of the present invention, a plant body temperature observation device under covering material has a housing which forms a closed space, the inside of which is divided into a cooling chamber and a heating chamber, a convex portion in which a heater is arranged is connected to the cooling chamber, a cooling plate cooled by a refrigerator and a fan for circulating air in the cooling chamber are arranged in the cooling chamber, a fan for circulating air in the heating chamber and a simulation body simulating the ground are arranged in the heating chamber, a plant model comprising a leaf temperature sensor according to one embodiment of the present invention is arranged on top of the simulation body, a rubber heater is arranged on the bottom of the simulation body, and a covering material is stretched between the cooling chamber and the heating chamber.

[0015] A leaf temperature / air temperature difference observation method according to one embodiment of the present invention is a leaf temperature / air temperature difference observation method that observes the difference between leaf temperature and air temperature using a plant body temperature observation device under covering material according to one embodiment of the present invention, and includes setting target temperatures for each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber, controlling the operation of the refrigerator, the heater, the rubber heater, and the fan so as to bring each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber closer to the target temperatures, and recording the detection value of the leaf temperature sensor.

[0016] In another embodiment of the present invention, a plant body temperature observation device under covering material has a housing which forms a closed space, the inside of which is divided into a cooling chamber and a heating chamber, a convex portion in which a heater is arranged is connected to the cooling chamber, a cooling plate cooled by a refrigerator and a fan for circulating air in the cooling chamber are arranged in the cooling chamber, a fan for circulating air in the heating chamber and a simulated body simulating the ground are arranged in the heating chamber, a plant model comprising a leaf temperature sensor according to another embodiment of the present invention is arranged on top of the simulated body, a rubber heater is arranged on the bottom of the simulated body, and a covering material is stretched between the cooling chamber and the heating chamber.

[0017] A method for observing changes in leaf temperature according to one embodiment of the present invention is a method for observing changes in leaf temperature using a plant body temperature observing device under a covering material according to another embodiment of the present invention, and includes setting target temperatures for each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber, controlling operation of the refrigerator, the heater, the rubber heater, and the fan so as to bring each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber closer to the target temperatures, analyzing the detection value of the leaf temperature sensor, and outputting predetermined information based on the results of analyzing the detection value of the leaf temperature sensor. Effect of the Invention

[0018] According to one aspect of the present invention, the influence of weather and external environment can be suppressed, and leaf temperature can be measured stably over a long period of time under different covering materials. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing an example of a plant model. [Diagram 2] FIG. 2 is a diagram for explaining an example of the internal configuration of the leaf temperature sensor according to the first embodiment, and is a cross-sectional view of a leaf of a plant model. [Diagram 3] FIG. 2 is a diagram showing an example of the electrical configuration of the leaf temperature sensor according to the first embodiment. [Figure 4] FIG. 11 is a diagram for explaining an example of the internal configuration of a leaf temperature sensor according to embodiment 2, and is a cross-sectional view of a leaf of a plant model. [Diagram 5] FIG. 11 is a diagram showing an example of the electrical configuration of a leaf temperature sensor according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view for explaining a configuration example of a plant body temperature observation device under a covering material according to a third embodiment. [Figure 7] 13 is a graph showing the results of observing changes in ΔTleaf using a plant body temperature observation device under a covering material. [Figure 8] 13 is a flowchart illustrating an example of the flow of a covering material heat retention performance evaluation process. [Figure 9] 13 is a flowchart illustrating an example of the flow of a leaf temperature change observation process. [Figure 10] FIG. 1 illustrates an example of the configuration of a computer that executes program instructions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [Embodiment 1] An embodiment of the present invention will be described in detail below. Figs. 1 to 3 are diagrams for explaining an example of the configuration of a leaf temperature sensor according to this embodiment. The leaf temperature sensor according to this embodiment detects the difference (referred to as ΔTleaf) between the leaf temperature of a plant and the air temperature so that a drop in the body temperature of the plant, such as a cultivated agricultural crop, can be detected. Note that the leaf temperature sensor according to this embodiment detects ΔTleaf related to a plant, such as an agricultural crop, by measuring the difference between the leaf temperature of a real plant and the air temperature, rather than the difference between the leaf temperature of a plant model and the air temperature.

[0021] The leaf temperature sensor 10A of this embodiment is a thermocouple made of two different metals and has a first junction and a second junction where the two metals are connected, the thermocouple having the first junction located inside the leaf of the plant model and the second junction located outside the leaf, and a voltage meter that measures the voltage generated by the thermocouple, and the plant model is formed so that the thickness and emissivity of the leaf are approximately the same as those of a real leaf.

[0022] (Plant model) Fig. 1 is a diagram showing an example of a plant model. As shown in the figure, the plant model 20 has a leaf portion 21 and a stem portion 22. In the plant model 20, the thickness and emissivity of the leaf portion 21 are made to be similar to those of a real leaf, thereby approaching the thermal characteristics of the leaves of an actual plant. Since the leaves of an actual plant generally have an emissivity of about 1, the leaf portion 21 of the plant model 20 is coated with a black body paint with an emissivity of 0.94.

[0023] The thickness and emissivity of the leaf 21 may be changed depending on the plant that is the target of detection of ΔTleaf.

[0024] (Example of the internal configuration of a leaf temperature sensor) 2 is a diagram for explaining an example of the internal configuration of the leaf temperature sensor according to this embodiment, and is a cross-sectional view of a leaf 21 of a plant model 20. As shown in the figure, the leaf temperature sensor 10A has a contact 41 for measuring leaf temperature arranged inside the leaf 21, and a contact 42 for measuring air temperature arranged outside the leaf 21. Note that the inside of the leaf 21 is actually configured to fit tightly without any gaps.

[0025] The leaf temperature measuring contact 41 and the air temperature measuring contact 42 are each connected to different metals, and these metals form a thermocouple 40.

[0026] (Example of electrical configuration of leaf temperature sensor) Fig. 3 is a diagram showing an example of the electrical configuration of the leaf temperature sensor according to this embodiment. As shown in the figure, the leaf temperature sensor 10A is configured using a thermocouple 40 made of two different metals, for example, copper (shown by a solid line in the figure) and constantan (shown by a dotted line in the figure). The points where the two different metals are connected are respectively a leaf temperature measurement contact 41 and an air temperature measurement contact 42.

[0027] The thermocouple 40 is connected to a voltage measuring device 47, which measures the voltage generated by the thermocouple 40. This makes it possible to measure a voltage corresponding to the difference between the temperature of the leaf temperature measuring contact 41 and the temperature of the air temperature measuring contact 42. The voltage measured by the voltage measuring device 47 is converted into a temperature, which indicates a temperature corresponding to the difference between the temperature of the leaf 21 of the plant model 20 and the air temperature. Here, a configuration is shown in which the difference between the leaf temperature and the air temperature is measured using a thermocouple 40, but other configurations can be used. For example, at least two highly accurate temperature sensors may be used to measure the air temperature and the leaf temperature separately and determine the difference. However, this will be more expensive than the case shown in FIG. 3.

[0028] (Effects of the First Embodiment) As described above, the leaf temperature sensor 10A according to this embodiment is configured by attaching the thermocouple 40 to the leaf 21 of the plant model 20, and therefore can detect ΔTleaf stably for a long period of time. For example, when attaching a thermocouple to the leaf of an actual plant, an error may occur in the detected ΔTleaf due to the plant's sleep behavior or growth, or the thermocouple may become detached from the leaf during detection of ΔTleaf.

[0029] The leaf temperature sensor 10A according to this embodiment can detect ΔTleaf without being affected by the sleep-entering movement or growth of the plant, and can therefore perform detection stably for a long period of time.

[0030] Furthermore, the leaf temperature sensor 10A according to this embodiment has the emissivity and thickness of the leaf 21 of the plant model 20 close to those of an actual leaf, improving the ability to follow temperature changes of an actual leaf. Therefore, for example, it is possible to detect ΔTleaf more accurately compared to the case where the leaf temperature is simulated by simply arranging the electrodes, sensing parts, etc. of the sensor.

[0031] Furthermore, the leaf temperature sensor 10A according to this embodiment is configured with a thermocouple so that a potential difference occurs when a difference occurs between the leaf temperature and the air temperature. For example, when measuring the leaf temperature and the air temperature with different sensors, a highly accurate sensor is required according to the respective applications, but by using the leaf temperature sensor 10A according to this embodiment, it becomes possible to detect ΔTleaf accurately at low cost.

[0032] [Embodiment 2] Next, another embodiment of the present invention will be described in detail. Figures 4 and 5 are diagrams for explaining a configuration example of a leaf temperature sensor according to this embodiment. The leaf temperature sensor according to this embodiment detects the leaf temperature of a plant, such as a cultivated agricultural crop, so that the plant's body temperature can be detected. Note that components having the same functions as those described in the above embodiment are given the same reference numerals, and their description will be omitted as appropriate.

[0033] Also, similarly to the above-described first embodiment, the leaf temperature sensor according to this embodiment detects the body temperature of a plant, such as a crop, by measuring the leaf temperature of a plant model.

[0034] The leaf temperature sensor 10B of this embodiment includes a temperature measurement point arranged inside the leaf of the plant model and a temperature detector that measures the temperature at the temperature measurement point, and the plant model is formed so that the thickness and emissivity of the leaf are similar to those of a real leaf. Any type of temperature sensor can be used.

[0035] (Example of the internal configuration of a leaf temperature sensor) 4 is a diagram for explaining an example of the internal configuration of the leaf temperature sensor according to this embodiment, and is a cross-sectional view of the leaf 21 of the plant model 20. As shown in the figure, the leaf temperature sensor 10B has a leaf temperature measurement point 61 arranged inside the leaf 21. Note that the inside of the leaf 21 is actually configured to be tightly fitted together with no gaps.

[0036] (Example of electrical configuration of leaf temperature sensor) 5 is a diagram showing an example of the electrical configuration of the leaf temperature sensor according to this embodiment. As shown in the figure, the leaf temperature sensor 10B is configured with a temperature sensor such as a thermistor, and is configured using a temperature detector 67 that detects the temperature of the leaf temperature measurement point 61 by detecting the resistance value. This makes it possible to detect the temperature of the leaf temperature measurement point 61, i.e., the temperature of the leaf 21 of the plant model 20. Note that a temperature sensor other than a thermistor may be used.

[0037] Thus, unlike the first embodiment, the leaf temperature sensor 10B according to this embodiment does not necessarily have to be configured using a thermocouple.

[0038] (Effects of the second embodiment) As described above, the leaf temperature sensor 10B according to this embodiment is configured by providing the leaf temperature measurement point 61 inside the leaf 21 of the plant model 20, so that the leaf temperature can be stably detected for a long period of time even outdoors or in a greenhouse. For example, when a thermocouple is attached to the leaf of an actual plant, an error may occur in the detected leaf temperature due to the plant's sleep movement or growth, or the thermocouple may become detached from the leaf during detection of the leaf temperature.

[0039] The leaf temperature sensor 10B according to this embodiment can detect leaf temperature without being affected by the dormancy movement or growth of the plant, and can therefore perform detection stably for a long period of time.

[0040] Furthermore, the leaf temperature sensor 10B according to this embodiment has the emissivity and thickness of the leaf 21 of the plant model 20 closer to those of an actual leaf, improving the ability to follow temperature changes of an actual leaf. This allows the sensor to detect leaf temperature more accurately than when the electrodes, sensing parts, etc. of the sensor are directly arranged to simulate leaf temperature.

[0041] [Embodiment 3] Next, a further embodiment of the present invention will be described in detail. Note that components having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0042] In this embodiment of the plant body temperature observation device under covering material, the inside of a housing forming a closed space is divided into a cooling chamber and a heating chamber, a convex part in which a heater is arranged is connected to the cooling chamber, a cooling plate cooled by a refrigerator and a fan for circulating air in the cooling chamber are arranged in the cooling chamber, a fan for circulating air in the heating chamber and a simulation body simulating the ground are arranged in the heating chamber, a plant model comprising the leaf temperature sensor described above with reference to Figures 2 and 3 is arranged on the top of the simulation body, a rubber heater is arranged on the bottom of the simulation body, and covering material is stretched between the cooling chamber and the heating chamber.

[0043] (Configuration of plant body temperature observation device under covering material) 6 is a cross-sectional view for explaining a configuration example of a plant body temperature observation device under a covering material according to the present embodiment. The plant body temperature observation device 100 shown in the figure is a device for observing changes in plant body temperature under a covering material, for example, for plants such as cultivated agricultural crops.

[0044] The plant body temperature monitoring device 100 under a covering material shown in Fig. 6 has a housing 101. The inside of the housing 101 is divided into a cooling chamber 111 and a heating chamber 112, and a covering material 140 is stretched over the boundary between the cooling chamber 111 and the heating chamber 112.

[0045] Furthermore, a protrusion 102 is formed in the upper left portion of the housing 101, and a heater 123 is disposed inside the protrusion 102. The protrusion 102 is connected to the cooling chamber 111, and configured to circulate the air inside the protrusion 102 and the air inside the cooling chamber 111 by fans 122-1 and 122-2.

[0046] A cooling plate 121 is disposed in the cooling chamber 111. The cooling plate 121 is configured to be connected to a refrigerator 120 disposed outside the housing 101 and cooled. The fan 122-3 circulates the air cooled by the cooling plate 121. That is, the air in the cooling chamber 111 is cooled by the cooling plate 121, and is circulated with air heated by the heater 123 as necessary. In addition, the cooling of the cooling plate 121 causes radiation cooling to occur in the heating chamber 112 during winter nights.

[0047] A heat insulating material 124 is arranged on the inner surface of the heating chamber 112. A ground simulant 125 is arranged in the heating chamber 112, and a plant model 20 is arranged on the ground simulant 125. The plant model 20 may be, for example, a plant model similar to that described above with reference to FIG.

[0048] A rubber heater 126 is disposed under the simulation body 125. The air heated by the rubber heater 126 is circulated by the fan 122-4. Then, the heated air mixes with the air above the simulation body 125. It is to be noted that a fan may also be provided above the simulation body 125.

[0049] That is, the heating chamber 112 is an environment simulating the inside of a greenhouse formed, for example, using the covering material 140, and the drop in temperature inside the greenhouse due to a drop in the outside temperature is reproduced by transmitting the temperature of the cooling chamber 111 through the covering material 140. Also, the air heated by the rubber heater 126 mixes with the air on the simulant 125, reproducing the rise in temperature caused by a heater in the greenhouse during winter nights.

[0050] The leaf 21 of the plant model 20 placed in the heating chamber 112 is configured as the leaf temperature sensor 10A described above with reference to Figures 2 and 3. Then, by analyzing the temperature detected by the leaf temperature sensor 10A, that is, the difference between the temperature of the leaf 21 of the plant model 20 and the temperature in the heating chamber 112, the change in ΔTleaf can be observed.

[0051] Computer 161 is configured to be able to communicate with refrigerator 120, heater 123, rubber heater 126, fans 122-1 to 122-4, and leaf temperature sensor 10A, for example, via wireless LAN router 162. Computer 161 controls the operations of refrigerator 120, heater 123, rubber heater 126, and fans 122-1 to 122-4, for example, by transmitting predetermined signals, data, etc.

[0052] Alternatively, computer 161 and wireless LAN router 162 may not be provided, and the operations of refrigerator 120, heater 123, rubber heater 126, and fans 122-1 to 122-4 may be controlled in response to operations inputted via a control panel, etc. Furthermore, the detection results of leaf temperature sensor 10A may be outputted to, for example, a predetermined sensor signal processing device.

[0053] 6 is a cross-sectional view of the plant body temperature observation device 100 under a covering material, and is therefore illustrated so that the inside can be observed, but in reality, a closed space is formed by the housing 101 and the protruding portion 102. For example, the housing 101 may be provided with a door, and after the installation of the plant model 20 and the spreading of the covering material 140 are completed, the door may be closed to form the closed space.

[0054] The drop in plant body temperature is mainly caused by heat loss due to radiative heat exchange between the plant's leaves and the sky. In other words, as heat loss due to radiative heat exchange increases, the leaf temperature becomes lower than the air temperature. The radiation of long-wavelength electromagnetic waves (long-wave radiation) with wavelengths of around 4 to 100 μm emitted by the Earth's atmosphere and surface is also called infrared radiation or thermal radiation. For example, the drop in leaf temperature of crops grown in a greenhouse is largely influenced by the long-wave radiation transmittance of the covering materials that make up the greenhouse.

[0055] If the leaf temperature continues to drop for a long period of time, it will have a negative impact on the leaf development and fruit maturation rate, so it is desirable to build a greenhouse using covering materials that can minimize ΔTleaf. The heat transfer coefficient (Wm -2 ℃ -1 The thermal conductivity is the rate at which heat is transferred per unit area when the temperature difference is 1 degree, and is a heat transfer coefficient that includes not only radiation but also conduction and convection.

[0056] For example, the thermal conductivity of a coating material made of glass is 5.8 Wm -2 ℃ -1 The thermal conductivity of the covering material made of agricultural vinyl chloride film is 6.4Wm -2 ℃ -1 The thermal conductivity of the covering material made of agricultural polyethylene film is 6.8Wm -2 ℃ -1 It is.

[0057] On the other hand, since the heat transfer coefficient includes heat conduction and heat transfer, even if the heat transfer coefficient of the covering material is known, it is not possible to estimate the heat loss due to radiative heat exchange between the leaves and the sky according to the temperature difference inside and outside the greenhouse. Also, although it is possible to compare the general thermal insulation performance of covering materials using the long radiation transmittance, it is difficult to predict the actual ΔTleaf from the long radiation transmittance alone.

[0058] Therefore, in this embodiment, the device 100 for observing the plant body temperature under a covering material is used to observe ΔTleaf over a long period of time, thereby making it possible to evaluate the heat retention performance of the covering material.

[0059] When observing ΔTleaf using the plant body temperature observation device 100 under a covering material, the target temperatures of the cooling plate 121, the cooling chamber 111, and the heating chamber 112 are set so as to approximate the environment during a winter night in the place where the plant is grown. For example, the target temperature of the cooling plate 121 is set to -22°C, the target temperature of the cooling chamber 111 to 0°C, and the target temperature of the heating chamber 112 to 15°C.

[0060] Then, the refrigerator 120, heater 123, rubber heater 126, and fan 122 (collectively referred to as fan 122 here) are operated to start up the plant body temperature monitoring device 100 under a covering material. After that, the operation of the refrigerator 120, heater 123, rubber heater 126, and fan 122 is controlled so that the temperature of the cooling plate 121, the temperature of the cooling chamber 111, and the temperature of the heating chamber 112 approach their respective target temperatures.

[0061] For example, one hour after startup, the temperatures of the cooling plate 121, the cooling chamber 111, and the heating chamber 112 will stabilize near the target temperature, so ΔTleaf is observed for about five hours from one hour after startup. That is, the detection value of the leaf temperature sensor 10A is recorded.

[0062] (Examples of observation results) 7 is a graph showing the results of observing the change in ΔTleaf using the plant body temperature observation device under the covering material 100. In this example, the change in ΔTleaf was observed using glass and agricultural polypropylene (agricultural polyethylene film) as the covering material 140.

[0063] Two graphs are shown in Fig. 7. The upper graph in Fig. 7 shows the change in ΔTleaf when glass is used as the covering material 140, and the lower graph in Fig. 7 shows the change in ΔTleaf when agricultural poly is used as the covering material 140. The vertical axis in the graph in Fig. 7 represents the value of ΔTleaf (leaf temperature - air temperature (°C)), and the horizontal axis represents the elapsed time after the start-up of the plant body temperature observation device 100 under a covering material.

[0064] The leaf temperature sensors 10-1, 10-2, and 10-3 were constructed using three different leaves 21-1, 21-2, and 21-3 of the leaf 21 of the plant model 20, and ΔTleaf was detected. The ΔTleaf detected by the leaf temperature sensors 10-1, 10-2, and 10-3 are shown as L1, L2, and L3, respectively, in the graph.

[0065] As shown in the graph of Fig. 7, the value of ΔTleaf starts to stabilize about 30 minutes to 1 hour after the start-up of the device 100 for observing a plant's body temperature under a covering material. In the upper graph of Fig. 7, the absolute value of the average value of the ΔTleaf values ​​detected by the three leaf temperature sensors from 1 hour to 5 hours after the start-up of the device 100 for observing a plant's body temperature under a covering material was 1.1°C. In the lower graph of Fig. 7, the absolute value of the average value of the ΔTleaf values ​​detected by the three leaf temperature sensors from 1 hour to 5 hours after the device 100 for observing a plant's body temperature under a covering material was 2.3°C.

[0066] Therefore, the use of glass as a covering material can reduce ΔTleaf compared to the use of agricultural polystyrene, and glass can be evaluated as having better performance as a covering material than agricultural polystyrene. This is thought to be due to the fact that the longwave radiation transmittance of glass is smaller than that of agricultural polystyrene.

[0067] In this manner, the plant body temperature observation device 100 under a covering material can be used to evaluate the performance of the covering material.

[0068] (Flow of the process for evaluating the thermal insulation performance of covering materials) Next, a process for evaluating the heat retention performance of a covering material will be described using the covering material-under-cover plant body temperature observation device 100. Fig. 8 is a flowchart illustrating an example of the flow of the covering material heat retention performance evaluation process.

[0069] In step S21, the plant model 20 equipped with the leaf temperature sensor 10A is placed in the heating chamber 112. At this time, the plant model 20 is placed, for example, as shown in FIG.

[0070] In step S22, the covering material 140 is spread between the cooling chamber 111 and the heating chamber 112 as a covering material to be evaluated. At this time, the covering material 140 is spread, for example, as shown in Fig. 6. Note that a plurality of covering materials may be spread in a layered manner.

[0071] In step S23, the target temperatures are set. At this time, the target temperature of the cooling plate 121 (e.g., −22° C.), the target temperature of the cooling chamber 111 (e.g., 0° C.), and the target temperature of the heating chamber 112 (e.g., 15° C.) are set. The set target temperatures may be input to, for example, a computer 161 installed outside the plant body temperature observation device 100 under a covering material.

[0072] Furthermore, the target temperature of the cooling plate 121, the target temperature of the cooling chamber 111, and the target temperature of the heating chamber 112 may be determined in advance, for example, according to the covering material to be evaluated, the region in which a greenhouse or the like is to be built using the covering material, etc. In this case, for example, when information specifying the type of covering material and the region in which a greenhouse or the like is to be built is input to the computer 161, the target temperature of the cooling plate 121, the target temperature of the cooling chamber 111, and the target temperature of the heating chamber 112 may be automatically set.

[0073] In step S24, the operation of refrigerator 120, heater 123, rubber heater 126, and fan 122 is controlled so that the temperatures of cooling plate 121, cooling chamber 111, and heating chamber 112 approach the target temperature set in step S23. The operation of refrigerator 120, heater 123, rubber heater 126, and fan 122 may be controlled by computer 161 to which the target temperature is input.

[0074] In step S25, it is determined whether or not the temperatures of the cooling plate 121, the cooling chamber 111, and the heating chamber 112 have stabilized. Note that in step S25, it may be determined whether or not a predetermined time (for example, one hour) has elapsed.

[0075] In step S25, the process waits until it is determined that the temperatures of cooling plate 121, cooling chamber 111, and heating chamber 112 are stable, and if it is determined that the temperatures are stable, the process of step S is executed.

[0076] In step S26, the detection value of the leaf temperature sensor 10A is recorded. The detection value of the leaf temperature sensor 10A may be input to, for example, a computer 161 or the like installed outside the plant body temperature observation device 100 under a covering material and recorded therein.

[0077] In step S27, it is determined whether the observation time (for example, 4 hours) has elapsed, and if it is determined that the observation time has not yet elapsed, the processes of steps S26 and S27 are repeatedly executed. If it is determined in step S27 that the observation time has elapsed, the process of step S28 is executed.

[0078] In step S28, a performance evaluation value corresponding to the covering material 140 spread in the process of step S22 is calculated. At this time, for example, the absolute value of the average value of the detection values ​​of the leaf temperature sensor 10A recorded in the process of step S26 is calculated and used as the performance evaluation value of the covering material 140.

[0079] After the process of step 28, the refrigerator 120, the heater 123, the rubber heater 126, and the fan 122 are stopped, and the process of evaluating the thermal insulation performance of the covering material is terminated.

[0080] In this manner, the process for evaluating the thermal insulation performance of the covering material is executed. Note that the processes from step S23 to step S28 described above may be automatically executed by the computer 161, for example.

[0081] In addition, in the above example, the absolute value of the average value of the detection values ​​of the leaf temperature sensor 10A recorded in the processing of step S26 was used as the performance evaluation value of the covering material 140, but the performance evaluation value of the covering material 140 may also be calculated by calculating the detection values ​​of the leaf temperature sensor 10A in another manner.

[0082] Furthermore, the detection value of the leaf temperature sensor 10A recorded in the process of step S26 may be used for a purpose other than calculating the performance evaluation value of the covering material 140. In other words, the process described above with reference to Fig. 8 does not necessarily have to be executed as a covering material heat retention performance evaluation process, and for example, the processes of steps S21 to S26 may be executed as a ΔTleaf (leaf temperature-air temperature difference) observation process.

[0083] (Effects of the Third Embodiment) When evaluating the performance of covering materials in outdoor greenhouses, it is necessary to take into account that plant body temperature changes depending on weather conditions. For example, when the weather is cloudy, downward infrared radiation increases, making it difficult for leaf temperature to decrease. For this reason, in order to compare the performance of multiple covering materials, it is necessary to observe leaf temperatures under the same weather conditions. In other words, multiple greenhouses using multiple covering materials each must be created, and observations must be made in those greenhouses simultaneously.

[0084] According to this embodiment, the target temperatures can be set and controlled for the cooling plate 121, the cooling chamber 111, and the heating chamber 112 in the plant body temperature observation device 100, which are closed spaces. Therefore, if the target temperatures are the same for observations using multiple covering materials, the observations can be carried out multiple times.

[0085] Also, by assuming the air temperature in the area where the plants are actually grown, it is possible to obtain highly reproducible observation results by setting target temperatures for the cooling plate 121, cooling chamber 111, and heating chamber 112 in the plant body temperature observation device 100 under a covering material. Therefore, for example, when a greenhouse is formed using a specific covering material, it is possible to predict in advance the drop in leaf temperature in winter for the plants grown in the greenhouse, and to plan cultivation suited to the conditions.

[0086] In addition, since the plant model 20 is placed in the heating chamber 112, it is possible to measure ΔTleaf with higher reproducibility without being affected by individual differences of plants. Therefore, by applying this embodiment, it is expected to improve efficiency in experiments for developing covering materials that do not easily lower leaf temperature.

[0087] In this way, according to the present embodiment, the effects of weather and the external environment can be suppressed, and the leaf temperature can be measured stably for a long period of time. As a result, it becomes possible to efficiently and accurately evaluate the performance of covering materials and to develop cultivation plans.

[0088] [Embodiment 4] Next, a further embodiment of the present invention will be described in detail. Note that components having the same functions as those described in the above embodiment are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0089] (Configuration of plant body temperature observation device under covering material) FIG. 6 can be used as a cross-sectional view for explaining a configuration example of a plant body temperature observation device under a covering material according to this embodiment. However, unlike the case of embodiment 3, the leaf 21 of the plant model 20 placed in the heating chamber is configured as the leaf temperature sensor 10B described above with reference to FIGS. 4 and 5. Then, by analyzing the temperature detected by the leaf temperature sensor 10B, i.e., the temperature of the leaf 21 of the plant model 20, a change in the leaf temperature can be observed.

[0090] That is, in the present embodiment, the inside of the housing forming a closed space is divided into a cooling chamber and a heating chamber, the convex portion in which the heater is arranged is connected to the cooling chamber, a cooling plate cooled by a refrigerator and a fan for circulating air in the cooling chamber are arranged in the cooling chamber, a fan for circulating air in the heating chamber and a simulation body simulating the ground are arranged in the heating chamber, a plant model comprising the leaf temperature sensor described above with reference to Figures 4 and 5 is arranged on the top of the simulation body, a rubber heater is arranged on the bottom of the simulation body, and the covering material is stretched between the cooling chamber and the heating chamber.

[0091] (Flow of leaf temperature change observation processing) Next, a description will be given of a process for observing changes in leaf temperature using the plant body temperature observing device 100 under a covering material. Fig. 9 is a flowchart illustrating an example of the flow of the process for observing changes in leaf temperature.

[0092] In step S51, the plant model 20 equipped with the leaf temperature sensor 10A is placed in the heating chamber 112. At this time, the plant model 20 is placed, for example, as shown in FIG.

[0093] In step S52, the covering material 140 is spread between the cooling chamber 111 and the heating chamber 112. At this time, the covering material 140 is spread, for example, as shown in Fig. 6. Note that a plurality of covering materials may be spread in a layered manner.

[0094] In step S53, the target temperatures are set. At this time, the target temperature of the cooling plate 121 (e.g., −22° C.), the target temperature of the cooling chamber 111 (e.g., 0° C.), and the target temperature of the heating chamber 112 (e.g., 15° C.) are set. The set target temperatures may be input to, for example, a computer 161 installed outside the plant body temperature observation device 100 under a covering material.

[0095] Furthermore, the target temperature of the cooling plate 121, the target temperature of the cooling chamber 111, and the target temperature of the heating chamber 112 may be determined in advance according to, for example, the region in which a greenhouse or the like is to be built using a covering material. In this case, for example, when information specifying the region in which a greenhouse or the like is to be built is input to the computer 161, the target temperature of the cooling plate 121, the target temperature of the cooling chamber 111, and the target temperature of the heating chamber 112 may be automatically set.

[0096] In step S54, the operation of refrigerator 120, heater 123, rubber heater 126, and fan 122 is controlled so that the temperatures of cooling plate 121, cooling chamber 111, and heating chamber 112 approach the target temperature set in step S53. The operation of refrigerator 120, heater 123, rubber heater 126, and fan 122 may be controlled by computer 161 to which the target temperature is input.

[0097] In step S55, it is determined whether or not the temperatures of the cooling plate 121, the cooling chamber 111, and the heating chamber 112 have stabilized. Note that in step S55, it may be determined whether or not a predetermined time (for example, one hour) has elapsed.

[0098] In step S55, the process waits until it is determined that the temperatures of cooling plate 121, cooling chamber 111, and heating chamber 112 are stable, and if it is determined that the temperatures are stable, the process of step S56 is executed.

[0099] In step S56, the detection value of the leaf temperature sensor 10B is analyzed. The detection value of the leaf temperature sensor 10B may be input to, for example, a computer 161 or the like installed outside the plant body temperature observation device 100 under a covering material, and analyzed.

[0100] In step S57, information based on the results of the analysis performed in step S56 is output. At this time, for example, it may be determined whether the leaf temperature has fallen below a preset threshold, and if it is determined that the leaf temperature has fallen below the threshold, a warning may be output. Also, for example, if the rate of change in leaf temperature within a predetermined time period exceeds a preset threshold, a warning may be output.

[0101] The warning may be, for example, a sound or an image, and may be output by the computer 161 that executed the analysis in step S56. Alternatively, the warning may be output by the computer 161 that executed the analysis in step S56 outputting a predetermined signal, data, or the like.

[0102] Alternatively, a predetermined signal may be output based on the average value of the detection values ​​of the leaf temperature sensor 10B within a unit time by the computer 161 that executed the analysis in step S56. For example, a control signal for a greenhouse heater may be output in response to the average value of the detection values ​​of the leaf temperature sensor 10B within a unit time.

[0103] After the process of step S57, the leaf temperature change observation process ends. Alternatively, the leaf temperature change observation process may end after a predetermined time has elapsed since it was determined in step S55 that the temperature has stabilized.

[0104] In this manner, the leaf temperature change observation process is executed. Note that the processes in steps S53 to S57 described above may be automatically executed by the computer 161, for example.

[0105] (Effects of the fourth embodiment) By assuming the temperature in the area where the plants are actually grown, and setting target temperatures for the cooling plate 121, the cooling chamber 111, and the heating chamber 112 in the plant body temperature observation device 100 under a covering material, it becomes possible to obtain highly reproducible observation results. Therefore, for example, by executing the leaf temperature change observation process at night in winter, it is possible to detect and warn of a drop in leaf temperature that may affect the growth of the plants.

[0106] This allows, for example, a grower who senses the warning to control a heater in the greenhouse to heat the greenhouse. Alternatively, for example, if the greenhouse heater is controlled by the signal or data output by the computer 161 as a warning, it is possible to automatically heat the greenhouse when a drop in leaf temperature that may affect plant growth is detected.

[0107] Alternatively, the leaf temperature sensor 10B may be installed in a greenhouse where plants are grown, and the detection value of the leaf temperature sensor 10B may be output to a heater. In this way, it becomes possible to control the heater so that the leaf temperature, rather than the air temperature, becomes the target temperature.

[0108] Furthermore, when the leaf temperature falls below the dew point, condensation occurs on the leaf surface, which induces the occurrence of pests. The leaf temperature sensor 10B can stably detect the leaf temperature for a long period of time without being affected by the plant's sleep behavior or growth, and can appropriately find the conditions under which the leaf temperature falls below the dew point depending on the change in air temperature and the type of covering material. Therefore, according to this embodiment, it is possible to estimate the condensation on the leaf surface during the cultivation period, for example.

[0109] (Example of software implementation) As described above, the processes of steps S23 to S28 of the covering material heat retention performance evaluation process may be automatically executed by, for example, a program read by the computer 161. Also, the processes of steps S53 to S57 of the leaf temperature change observation process may be automatically executed by, for example, a program read by the computer 161.

[0110] Fig. 10 is a block diagram illustrating a physical configuration of the computer 161. As shown in Fig. 10, the computer 161 can be configured by a computer including a bus 510, a processor 501, a main memory 502, an auxiliary memory 503, a communication interface 504, and an input / output interface 505. The processor 501, the main memory 502, the auxiliary memory 503, the communication interface 504, and the input / output interface 505 are connected to each other via the bus 510. An input device 506 and an output device 507 are connected to the input / output interface 505.

[0111] The processor 501 may be, for example, a CPU (Central Processing Unit), a microprocessor, a digital signal processor, a microcontroller, or a combination of these.

[0112] As the main memory 502, for example, a semiconductor RAM (random access memory) or the like is used.

[0113] A flash memory, a hard disk drive (HDD), a solid state drive (SSD), or a combination of these may be used as the auxiliary memory 503. A program for causing the processor 501 to execute the processes of steps S23 to S28 of the covering material heat retention performance evaluation process or steps S53 to S57 of the leaf temperature change observation process described above is stored in the auxiliary memory 503. The processor 501 loads the program stored in the auxiliary memory 503 onto the main memory 502, and executes each command included in the loaded program.

[0114] The above program may be recorded non-transiently in one or more recording media readable by the computer 161. The recording media may or may not be included in the computer 161. In the latter case, the above program may be supplied to the computer 161 via any wired or wireless transmission medium.

[0115] The communication interface 504 is an interface for connecting to the network N.

[0116] As the input / output interface 505, for example, a USB interface, a short-range communication interface such as infrared or Bluetooth (registered trademark), or a combination of these is used.

[0117] The input device 506 may be, for example, a keyboard, a mouse, a touch pad, a microphone, or a combination of these. The output device 507 may be, for example, a display, a printer, a speaker, or a combination of these.

[0118] 〔summary〕 The leaf temperature sensor of aspect 1 of the present invention comprises a thermocouple made of two different metals and having a first junction and a second junction where the two metals are connected, the first junction being arranged inside a leaf of a plant model and the second junction being arranged outside the leaf, and a voltage meter that measures the voltage generated by the thermocouple, and the plant model is formed so that the thickness and emissivity of the leaf are approximately the same as those of a real leaf.

[0119] A leaf temperature sensor according to a second aspect of the present invention is the same as that of the first aspect, except that the leaf portion is coated with a black body paint having an emissivity of 0.94.

[0120] A leaf temperature sensor according to a third aspect of the present invention is the same as that of the first or second aspect, wherein the two metals are copper and constantan.

[0121] The leaf temperature sensor of aspect 4 of the present invention comprises a temperature measurement point arranged inside a leaf of a plant model and a temperature detector for measuring the temperature at the temperature measurement point, and the plant model is formed so that the thickness and emissivity of the leaf are approximately the same as those of a real leaf.

[0122] A leaf temperature sensor according to a fifth aspect of the present invention is the same as that of the fourth aspect, in which the leaf portion is coated with black body paint having an emissivity of 0.94.

[0123] In the plant body temperature observation device under covering material of aspect 6 of the present invention, the inside of a housing forming a closed space is divided into a cooling chamber and a heating chamber, a convex portion in which a heater is arranged is connected to the cooling chamber, a cooling plate cooled by a refrigerator and a fan for circulating air in the cooling chamber are arranged in the cooling chamber, a fan for circulating air in the heating chamber and a simulated body simulating the ground are arranged in the heating chamber, a plant model comprising a leaf temperature sensor described in any of aspects 1 to 3 above is arranged on top of the simulated body, a rubber heater is arranged on the bottom of the simulated body, and a covering material is stretched between the cooling chamber and the heating chamber.

[0124] A leaf temperature / air temperature difference observation method according to aspect 7 of the present invention is a leaf temperature / air temperature difference observation method for observing the difference between leaf temperature and air temperature using the plant body temperature observation device under covering material described in aspect 6 above, and includes setting target temperatures for each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber, controlling the operation of the refrigerator, the heater, the rubber heater, and the fan so as to bring each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber closer to the target temperatures, and recording the detection value of the leaf temperature sensor.

[0125] The leaf temperature / air temperature difference observation method of aspect 8 of the present invention, in accordance with aspect 7 above, further includes calculating an evaluation value for representing the performance of the covering material based on the recorded detection value of the leaf temperature sensor.

[0126] A leaf temperature / air temperature difference observation method according to aspect 9 of the present invention, in accordance with aspect 7 above, calculates an evaluation value of the covering material to be evaluated based on the detection value of the leaf temperature sensor one hour after the operation of the refrigerator, the heater, the rubber heater, and the fan is started.

[0127] In the plant body temperature observation device under covering material of aspect 10 of the present invention, the inside of a housing forming a closed space is divided into a cooling chamber and a heating chamber, a convex portion in which a heater is arranged is connected to the cooling chamber, a cooling plate cooled by a refrigerator and a fan for circulating air in the cooling chamber are arranged in the cooling chamber, a fan for circulating air in the heating chamber and a simulated body simulating the ground are arranged in the heating chamber, a plant model comprising a leaf temperature sensor described in aspect 4 or aspect 5 above is arranged on top of the simulated body, a rubber heater is arranged on the bottom of the simulated body, and a covering material is stretched between the cooling chamber and the heating chamber.

[0128] A leaf temperature change observation method according to aspect 11 of the present invention is a leaf temperature change observation method using the plant body temperature observation device under a covering material described in aspect 10 above, and includes setting target temperatures for each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber, controlling the operation of the refrigerator, the heater, the rubber heater, and the fan so as to bring each of the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber closer to the target temperatures, analyzing the detection value of the leaf temperature sensor, and outputting specified information based on the analysis result of the detection value of the leaf temperature sensor.

[0129] In the leaf temperature change observation method of aspect 12 of the present invention, in the above-mentioned aspect 11, the specified information output based on the analysis results is a warning output when the temperature corresponding to the detection value of the leaf temperature sensor falls below a predetermined threshold value.

[0130] A leaf temperature change observation method according to aspect 13 of the present invention is characterized in that, in the above-mentioned aspect 11, the specified information output based on the analysis results is a control signal for a greenhouse heater corresponding to the average detection value of the leaf temperature sensor within a unit time. [Explanation of symbols]

[0131] 10A Leaf Temperature Sensor 10B Leaf temperature sensor 20 Plant model 21 Leaf 22 Stem 40 Thermocouple 41 Contact point for leaf temperature measurement 42 Temperature measuring contact 61 Leaf temperature measurement point 100 Plant body temperature observation device under covering material 101 Case 111 Cooling room 112 Heating chamber 120 Refrigeration Machine 121 Cooling plate 122 Fans 123 Heater 125 Simulation 126 Rubber heater 140 Covering materials

Claims

1. A thermocouple made of two different metals, the thermocouple having a first junction and a second junction where the two metals are connected, the first junction being disposed inside a leaf of a plant model, and the second junction being disposed outside the leaf; a voltage measuring device that measures a voltage generated by the thermocouple; The plant model is formed so that the thickness and emissivity of the leaf portion are similar to those of a real leaf. Leaf temperature sensor.

2. The leaves are coated with black paint, which has an emissivity of 0.

94. The leaf temperature sensor according to claim 1 .

3. The two metals are copper and constantan. The leaf temperature sensor according to claim 1 .

4. Temperature measuring points arranged inside the leaves of the plant model; a temperature detector for measuring the temperature at the temperature measurement point; The plant model is formed so that the thickness and emissivity of the leaf portion are similar to those of a real leaf. Leaf temperature sensor.

5. The leaves are coated with black paint, which has an emissivity of 0.

94. The leaf temperature sensor according to claim 4.

6. The inside of the housing, which forms a closed space, is divided into a cooling chamber and a heating chamber, The protrusion on which the heater is disposed is connected to the cooling chamber, The cooling chamber includes: A cooling plate cooled by a refrigerator; A fan for circulating air in the cooling chamber is provided, The heating chamber includes: A fan for circulating air in the heating chamber; A mock ground was placed on the ground. A plant model including the leaf temperature sensor according to claim 1 is placed on the upper part of the simulator, A rubber heater is disposed under the simulant body, A covering material is stretched between the cooling chamber and the heating chamber. Plant body temperature monitoring device under covering material.

7. A method for observing a leaf temperature and air temperature difference, comprising the steps of: observing a difference between leaf temperature and air temperature using the plant body temperature observation device under a covering material according to claim 6; setting target temperatures for the cooling plate temperature, the cooling chamber temperature, and the heating chamber temperature; controlling the operation of the refrigerator, the heater, the rubber heater, and the fan so that the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber approach the target temperatures, respectively; A leaf temperature and air temperature difference observation method including recording the detection value of the leaf temperature sensor.

8. The method further includes calculating an evaluation value representing the performance of the covering material based on the recorded detection value of the leaf temperature sensor. The leaf temperature / air temperature difference observation method according to claim 7.

9. The evaluation value of the covering material is calculated based on the detection value of the leaf temperature sensor one hour after the operation of the refrigerator, the heater, the rubber heater, and the fan is started. The leaf temperature / air temperature difference observation method according to claim 8.

10. The inside of the housing, which forms a closed space, is divided into a cooling chamber and a heating chamber, The protrusion on which the heater is disposed is connected to the cooling chamber, The cooling chamber includes: A cooling plate cooled by a refrigerator; A fan for circulating air in the cooling chamber is provided, The heating chamber includes: A fan for circulating air in the heating chamber; A mock ground was placed on the ground. A plant model including the leaf temperature sensor according to claim 4 is placed on the upper part of the simulator, A rubber heater is disposed under the simulant body, A covering material is stretched between the cooling chamber and the heating chamber. Plant body temperature monitoring device under covering material.

11. A method for observing changes in leaf temperature using the plant body temperature observation device under a covering material according to claim 10, setting target temperatures for the cooling plate temperature, the cooling chamber temperature, and the heating chamber temperature; controlling the operation of the refrigerator, the heater, the rubber heater, and the fan so that the temperature of the cooling plate, the temperature of the cooling chamber, and the temperature of the heating chamber approach the target temperatures, respectively; Analyzing the detection value of the leaf temperature sensor; and and outputting predetermined information based on the result of analyzing the detected value of the leaf temperature sensor. Methods for observing changes in leaf temperature.

12. The predetermined information output based on the analysis result is a warning that is output when the temperature corresponding to the detection value of the leaf temperature sensor falls below a preset threshold value. The method for observing changes in leaf temperature according to claim 11.

13. The predetermined information output based on the analysis result is a control signal for a greenhouse heater that corresponds to an average value of the detection value of the leaf temperature sensor within a unit time. The method for observing changes in leaf temperature according to claim 11.

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