CN105277589B - Based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves and its detection method - Google Patents

Based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves and its detection method Download PDF

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CN105277589B
CN105277589B CN201510582859.2A CN201510582859A CN105277589B CN 105277589 B CN105277589 B CN 105277589B CN 201510582859 A CN201510582859 A CN 201510582859A CN 105277589 B CN105277589 B CN 105277589B
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thermocouple
water
temperature difference
crop
temperture
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CN105277589A (en
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徐俊增
廖林仙
卫琦
吕玉平
杨士红
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Hohai University HHU
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Hohai University HHU
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Abstract

The present invention discloses a kind of based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves and its detection method, including abundant rising thing, thermocouple and micro voltage measuring instrument, the cold end of thermocouple is placed in the top layer of fully rising thing, the hot junction of thermocouple is affixed on tested crop blade face, and the hot junction of thermocouple and cold end are communicated in micro voltage measuring instrument after producing thermo-electromotive force.The present invention overcomes traditional temperature difference to need the defect of Simultaneous Determination leaf temperature and air (or fully rising thing surface), directly determine temperature increase of the blade relative to abundant rising face, and thermocouple precision is higher, price is relatively low simultaneously, it is easy to Data acquisition and storage, meets requirement of the field-crop water deficit detection to sensor.

Description

Based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves and its detection Method
Technical field
The present invention relates to agricultural irrigation monitoring technology, and in particular to one kind is based on the elevated crop water of thermocouple monitoring temperture of leaves Divide wane detection means and its detection method.
Background technology
The significance of crop plant transpiration consumption moisture is to cool for plant, when Crop water deficits, it is rising by To suppression, the energy of transpiration consumption is reduced, under certain radiation condition, Sensible Heating Flux increase, the temperature of crop itself and canopy Increase, and the increase of this temperature of crop can embody soil drought and air overdrying and obtain collective effect, in reflection crop It is better than traditional Moisture Index in terms of water deficit.
Therefore it is developed based on blade or canopy and the Crop water deficits detection technique research of atmospheric temperature difference, mesh The preceding quantitative study for raising reflection water deficit using surface temperature respectively in canopy and leaf scale has been reported.Current section The temperature value for determining canopy or blade in research using infrared radiation thermometer mostly is learned, determines and is calculated in conjunction with temperature It is preced with (leaf) air Temperature Difference.Crop moisture detection device and method, a kind of crop nitrogen and moisture Non-Destructive Testing based on multisensor Such infrared temperature sensor is employed in method and device and carries out canopy surface temperature monitoring.Infrared radiation thermometer or infrared temperature are passed Sensor is expensive, is only limitted to scientific research and uses, the also inconvenience application in guiding agricultural production.
Thermocouple is as a mature technology with solid theoretical foundation, and it is according to thermoelectricity caused by the temperature difference of galvanic couple two ends The temperature difference of kinetic potential, measurement hot junction and cold end, and cold junction temperature is obtained by distinct methods, calculating obtains monitoring point (i.e. hot junction) Temperature, current this technology extensive use in temperature survey, develops and differs from one another, is applicable the various types of of different needs Thermocouple product, cheap, precision is higher.
The content of the invention
Goal of the invention:It is an object of the invention to solve problems of the prior art there is provided one kind based on thermocouple Monitor the elevated Crop water deficits detection means of temperture of leaves and its detection method.
Technical scheme:It is of the present invention a kind of based on the elevated Crop water deficits detection dress of thermocouple monitoring temperture of leaves Put, including fully rising thing, thermocouple and micro voltage measuring instrument, the cold end of the thermocouple is placed in the top layer of fully rising thing, The hot junction of thermocouple is affixed on tested crop blade face, and the hot junction of thermocouple and cold end, which are produced, is communicated in micro voltage survey after thermo-electromotive force Measure instrument.
By directly observing the hot junction (surface of tested blade) of thermocouple and the temperature of cold end (the fully surface of transpiration thing) Difference is spent, blade is then based on relative to the regression relation between abundant rising thing surface temperature lift-off value and leaf water physiology Carry out the detection of water deficit.
Further, the hot junction of the thermocouple and cold end can also be all connected to AD digital-to-analogue conversions after producing thermo-electromotive force Device, the other end of AD digital analog converters is connected to signal amplifier, and the other end of signal amplifier is connected to Programmable digital display instrument Table.
Further, the other end of the signal amplifier is also directly connected to computer by data acquisition unit.
Further, the abundant rising thing includes containing in open type water receiver, water receiver on water, the water surface and floated completely The foamed polystyrene board of the water surface is covered, the upper surface of foamed polystyrene board and four sides are all covered with the non-woven fabrics that absorbs water Layer, the periphery of water suction nonwoven layer is enclosed with water imbibition gluing scrim cloth, water suction nonwoven layer and water imbibition gluing fiber cloth The surrounding of layer is immersed in the water.Wherein, the water in water receiver is relevant with water receiver depth, with wherein flotation gear top surface and storage The vessel port of hydrophone, which remains basically stable, to be advisable.Further, the abundant rising thing is placed in crop canopies height, and the water receiver is Length of side 30cm, depth 10cm cuboid water receiver (can certainly be other shapes, such as it is cylindric, if using rectangular Body, wants two edge lengths of bottom surface identical or relatively as far as possible), the thickness of foamed polystyrene board is 5cm, and absorb water non-woven fabrics The thickness of layer is 2mm.And fully transpiration thing size dimension can also be set according to the size of actual tested crop canopies, with The size of tested crop canopies is close and sets the length of side for principle.
Further, the thermocouple is the thermocouple of K-type, J-type or S types, and thermocouple is fixedly mounted by support.
The invention also discloses a kind of detection based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves Method, comprises the following steps:
(1) hot junction of thermocouple is placed directly within blade surface to be measured, the cold end of thermocouple is placed directly within manual simulation Abundant rising thing surface;
(2) when tested blade can not ensure sufficient transpiration due to water shortage, leaf temperature rise, fully transpiration thing Evaporate unrestricted temperature relatively low, produce thermo-electromotive force at thermocouple two ends, then obtain voltage data, by calculating and then examining Tested blade is surveyed whether to wane moisture;Wherein, voltage data can be obtained by following two modes, is specially:
(2-1) directly determines voltage readings evidence by using micro voltage measuring instrument, according to the characteristic parameter of thermocouple in itself The temperature difference between tested blade and fully rising thing surface is directly calculated, and then is carried out according to the critical temperature difference of water deficit Water deficit whether detection;
(2-2) is received by AD digital analog converters to be surveyed voltage signal and is converted to data signal, then again by numeral Signal amplifier amplifies signal, and the data signal after amplification can be handled by following two modes:
Data signal after (2-2-1) amplification is directly accessed Programmable digital display instrument, carries out calibration test and (sets up amplification Regression relation between rear digital signal value and the temperature difference, usually linear relationship) obtain between data signal and temperature difference Numerical signal, actual temperature difference is converted into by preprogramming by relation, is finally shown in real time in Programmable digital display instrument Temperature difference data variation;
(2-2-2) amplification after data signal can be directly connected to data acquisition unit, be then connected to computer, by with The software of data acquisition unit is programmed, and the relation between temperature difference and data signal is inputted into computer, different by setting Sampling and storage cycle can realize the dynamic monitoring and storage of the temperature difference.
Beneficial effect:Compared with prior art, the present invention has advantages below:
(1) principle according to the thermocouple measurement galvanic couple two ends temperature difference, determine leaf temperature relative to abundant rising face Temperature difference, both can manually carry out Crop water deficits detection, can also carry out Crop water deficits inspection automatically by developing software Survey, and be connected with automatic irrigation system, send instructions to automatic irrigation system, realize the startup of irrigation system.
(2) present invention it is cheap, can continuous monitoring temperture of leaves, for monitoring crop water regime, carry out water deficit Detect and instruct scientific application of irrigation to have great importance.
(3) relation between leaf temperature lift-off value and crop water physical signs by monitoring Different Crop etc., really Critical-temperature lift-off value of the Different Crop when different bearing stage produces water deficit is determined, when the blade monitored-fully steaming Mean to occur in that water deficit when the temperature difference exceedes critical temperature difference between fermentation, then need irrigation in time.
(4) present invention overcomes traditional temperature difference to need Simultaneous Determination leaf temperature and air (or fully rising thing surface) Defect, directly determine temperature increase of the blade relative to abundant rising face, and thermocouple precision is higher, while price phase To relatively low, it is easy to Data acquisition and storage, requirement of the field-crop water deficit detection to sensor is met.
In summary, the present invention has three kinds of modes and can measure the voltage difference of crop blade face and canopy, and then obtains the temperature difference, The water deficit state of crop may finally be judged, the present invention is easy to use, and measurement is accurate, and three kinds of modes can be selected arbitrarily.
Brief description of the drawings
Fig. 1 is system structure diagram of the invention;
Fig. 2 for the present invention in abundant rising thing structural representation;
Fig. 3 is by taking nickel chromium triangle-cupro-nickel (constantan) thermocouple (K-type or J-type) as an example between the thermocouple two ends temperature difference and electromotive force Relation schematic diagram;
Fig. 4 is the relation schematic diagram between rice leaf in embodiment-abundant evaporating surface between the temperature difference and stomatal conductance.
Embodiment
Technical solution of the present invention is described in detail below, but protection scope of the present invention is not limited to the implementation Example.
Principle 1:Seebeck effect, i.e., when with the presence of galvanic couple two ends thermograde, in loop just having electric current passes through, this When galvanic couple two ends between there is electromotive force (i.e. thermo-electromotive force), and be in linear pass between the numerical value and the two ends temperature difference of electromotive force System.By monitoring the electromotive force at cold and hot two ends, cold and hot two sections of temperature difference can be directly calculated.By the hot junction of thermocouple and plant Blade is fully contacted, and the cold end of thermocouple is placed in the surface fully evaporated, and it is relative directly to determine leaf to be measured by the principle Temperature rise in abundant rising surface.
Principle 2:A certain amount of to be radiated up to after plant top layer (such as blade), a part passes through plant in the form of latent heat Transpiration consume, a part causes the raising of plant canopy surface temperature, when water shortage occurs in plant, the water that consumes of transpiration Branch declines, and the energy for being used for canopy heating from energy balance angle will increase, and show as the raising of surface temperature.Cause This raises (relative to abundant rising surface) situation by monitoring plant surface temperature, can be used in Crop water deficits detection.
Furthermore, it is contemplated that field crops can not possibly individually maintain a part in long-term abundant rising state, adopt here With the face of the abundant rising thing 2 of a hypothesis come instead of the plant of adequate water supply not water shortage.
Embodiment 1:
As depicted in figs. 1 and 2, being detected based on the elevated Crop water deficits of thermocouple monitoring temperture of leaves for the present embodiment is filled Put, including thermocouple and fully rising thing 2, the cold end 1b of thermocouple is placed in the top layer of fully rising thing 2, the hot junction 1a of thermocouple Tested crop blade face is affixed on, the hot junction 1a and cold end 1b of thermocouple are communicated in AD digital analog converters 5, AD after producing thermo-electromotive force The other end of digital analog converter 5 is connected to signal amplifier 6, and the other end of signal amplifier 6 is connected to by data acquisition unit 8 Computer 9.
Above-mentioned abundant rising thing 2, which includes containing in open type water receiver 21, water receiver 21 on suitable quantity of water, the water surface, to be floated completely The foamed polystyrene board 22 of the water surface is covered, the upper surface of foamed polystyrene board 22 and four sides are all covered with the nonwoven that absorbs water Layer of cloth 23, the periphery of water suction nonwoven layer 23 is enclosed with water imbibition gluing scrim cloth 24, water suction nonwoven layer 23 and water imbibition The surrounding of gluing scrim cloth 24 is immersed in the water;And abundant rising thing 2 is placed in crop canopies height, water receiver 21 is side Long 30cm, depth 10cm cuboid water receiver 21, the thickness of foamed polystyrene board 22 is 5cm, water suction nonwoven layer 23 Thickness is 2mm.
Fig. 3 is to be the temperature difference and the relation of electromotive force of conventional nickel chromium triangle-cupro-nickel (constantan) thermocouple (K-type or J-type), root The thermocouple two ends electromotive force data collected according to present system, by the relation between the temperature difference and electromotive force, Ke Yiji Calculation obtains the temperature difference between rice leaf-abundant evaporating surface.
Pass between the rice leaf that Fig. 4 obtains for the present embodiment measurement-abundant evaporating surface between the temperature difference and stomatal conductance It is schematic diagram, test result indicates that:When the rice leaf blade face temperature difference is relatively low, blade face stomatal conductance is in larger aperture, but works as After the thermocouple two ends temperature difference is more than 0.7 degree Celsius, blade face stomatal conductance is gradually reduced, it is meant that paddy rice occurs in that moisture loses Lack, now its aperture of stomatal conductivity, stomatal conductance declines.It is considered that occurring the leaf of water deficit under this experimental condition Temperature difference critical value is in 0.7 degrees centigrade between piece-abundant evaporating surface., after the temperature difference that measurement is obtained is more than 0.7 degree Celsius Pour water in time.

Claims (6)

1. one kind is based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves, it is characterised in that:Including fully steaming Thing, thermocouple and micro voltage measuring instrument are risen, the cold end of the thermocouple is placed in the top layer of fully rising thing, the hot junction patch of thermocouple In tested crop blade face, micro voltage measuring instrument is communicated in after the hot junction of thermocouple and cold end generation thermo-electromotive force;It is described abundant Rising thing includes containing the foamed polystyrene board that the water surface is completely covered in floating on water, the water surface in open type water receiver, water receiver, The upper surface of foamed polystyrene board and four sides are all covered with the nonwoven layer that absorbs water, and the periphery of water suction nonwoven layer is enclosed with The surrounding of water imbibition gluing scrim cloth, water suction nonwoven layer and water imbibition gluing scrim cloth is immersed in the water.
2. according to claim 1 be based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves, its feature It is:The hot junction of the thermocouple and cold end can also be directly connected in AD digital analog converters, AD numbers after producing thermo-electromotive force The other end of weighted-voltage D/A converter is connected to signal amplifier, and the other end of signal amplifier is connected to Programmable digital display instrument.
3. according to claim 2 be based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves, its feature It is:The other end of the signal amplifier can also be connected to computer by data acquisition unit.
4. according to claim 1 be based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves, its feature It is:The abundant rising thing is placed in crop canopies height, and the water receiver is length of side 30cm, depth 10cm cuboid water storage Device, the thickness of foamed polystyrene board is 5cm, and the thickness of water suction nonwoven layer is 2mm.
5. according to claim 1 be based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves, its feature It is:The thermocouple is the thermocouple of K-type, J-type or S types, and thermocouple is fixedly mounted by support.
6. it is a kind of according to Claims 1 to 5 any one based on the elevated Crop water deficits of thermocouple monitoring temperture of leaves The detection method of detection means, it is characterised in that:Comprise the following steps:
(1) hot junction of thermocouple is placed directly within blade surface to be measured, the cold end of thermocouple is placed directly within filling for manual simulation Divide the surface of rising thing;
(2) when tested blade can not ensure sufficient transpiration due to water shortage, the evaporation of leaf temperature rise, fully transpiration thing Unrestricted temperature is relatively low, produces thermo-electromotive force at thermocouple two ends, then obtains voltage data, by calculating and then detecting quilt Survey whether blade wanes moisture;Wherein, voltage data can be obtained by following two modes, is specially:
(2-1) directly determines voltage readings evidence by using micro voltage measuring instrument, direct according to the characteristic parameter of thermocouple in itself The temperature difference between tested blade and fully rising thing surface is calculated, and then moisture is carried out according to the critical temperature difference of water deficit The detection whether waned;Wherein, the characteristic parameter of thermocouple in itself refers to Seebeck coefficient (μ V/ DEG C), i.e., temperature often raises 1 DEG C The voltage change brought;The process that temperature difference is directly calculated by voltage difference refers to between the hot junction and cold end actually measured Magnitude of voltage divided by Seebeck coefficient obtain the temperature gap at two ends;
(2-2) is received by AD digital analog converters to be surveyed voltage signal and is converted to data signal, and data signal is then passed through again Amplifier amplifies signal, and the data signal after amplification can be handled by following two modes:
Data signal after (2-2-1) amplification is directly accessed Programmable digital display instrument, carry out calibration test obtain data signal with Numerical signal, actual temperature difference is converted into by preprogramming by the relation between temperature difference, finally in Programmable digital display instrument Temperature difference data variation is shown in table in real time;
(2-2-2) amplification after data signal can be directly connected to data acquisition unit, be then connected to computer, by with data The software of collector is programmed, and the relation between temperature difference and data signal is inputted into computer, the different sampling by setting The dynamic monitoring and storage of the temperature difference can be realized with the storage cycle.
CN201510582859.2A 2015-09-14 2015-09-14 Based on the elevated Crop water deficits detection means of thermocouple monitoring temperture of leaves and its detection method Expired - Fee Related CN105277589B (en)

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CN107356291A (en) * 2017-07-31 2017-11-17 天津大学 A kind of flexible extending blade face sensor-based system and preparation method
CN107505521A (en) * 2017-08-10 2017-12-22 中国科学院上海高等研究院 The passive and wireless temperature rise sensor and detection method for temperature rise of a kind of power distribution network transformer
CN108469434B (en) * 2018-04-11 2022-01-25 山东农业大学 Device and method for monitoring whether fruit trees lack water
CN109000721B (en) * 2018-06-28 2021-05-07 浙江农林大学 Method for identifying key control points of Longjing tea mechanism process based on leaf temperature monitoring
CN113748867B (en) * 2021-09-10 2022-04-26 中国水利水电科学研究院 Precision discrimination method and system for farmland surface temperature monitoring data

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CN2563574Y (en) * 2002-07-16 2003-07-30 中国农业大学作物学院 Blade temperature differential instrument
CN1292253C (en) * 2003-07-16 2006-12-27 西北农林科技大学 Crop evaporation transpiration instrument
CN1315372C (en) * 2004-11-17 2007-05-16 中国农业科学院农田灌溉研究所 Irrigation control method and device according to crop water deficiency stress physiological reaction
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