CN1715880A - A portable non-destructive testing method and measuring instrument for plant nitrogen and moisture content - Google Patents

Abstract

The portable non-destructive plant nitrogen and water content detection system includes four wavelength spectral measurement device with oppositely set light source and detector, neutralized reference sample or leaf to be measured, micro controller connected to the light source and the detector, serial port circuit connected electrically to the micro controller, and display and keyboard connected electrically to the micro controller too. The detection method includes detecting data I0 and I, calculating the fresh leaf transmission T= I/I0 of different wavelengths, and calculating the plant chlorophyll, water content and relative content NI reflecting the nitrogen level in the leaf in chemical metering algorithm. Compared with traditional measurement method, the present invention has decades times raised efficiency and no production of environment harming matter, and may be used in great area fast field measurement.

Description

A portable non-destructive testing method and measuring instrument for plant nitrogen and moisture content

technical field

The invention relates to a system for detecting the nutritional status of plants, in particular to a portable non-destructive detection method and measuring instrument for plant nitrogen and water content.

Background technique

Nitrogen is an essential nutrient element for crop growth and development. It is a component of chlorophyll, protein, and nucleic acid in plants, and a component of many endogenous hormones, accounting for 1% to 7% of plant dry weight. Nitrogen compounds are mainly concentrated in areas where crop life activities are vigorous, such as leaves and meristems, etc. It is an essential nutrient element for crop growth and development, and is of great significance to crop life activities. In production practice and scientific research, we need to keep crops at an appropriate level of nitrogen, and we need to analyze the nitrogen content of crop plants. There are many existing methods for analyzing the nitrogen level of crops, such as concentrated sulfuric acid nitrification method, distillation method, diffusion method and so on. These methods have high precision, but they are all destructive to plants, and are time-consuming and expensive. These methods are of little practical value when real-time monitoring of nitrogen levels in crops is required. Chloroplast is the place where crops carry out photosynthesis, and it has the function of intercepting light energy. The level of chlorophyll content directly affects the photosynthesis of crops, and reflects the nitrogen content of leaves to a certain extent. The nitrogen level can be reflected by combining leaf water content and chlorophyll content to establish a relationship.

Contents of the invention

The purpose of the present invention is: to overcome the original chemical method, visible spectrum or liquid chromatography when measuring nitrogen content in plant leaves, its measurement speed is slow, the measurement process needs to consume reagents, and also produces waste liquid, which is harmful to the environment. Defects that cause pollution; more importantly, defects that cause damage to crop leaves when measuring nitrogen content in plant leaves; in order to achieve non-destructive testing of nitrogen content in crop leaves during field growth; thus providing a multi-purpose The wavelength corrects the background and removes the influence of background components to realize the non-destructive detection of the pigment content in the crop leaves. The system and method for the portable non-destructive detection of nitrogen nutrition status of field plants.

The purpose of the present invention is achieved like this:

The non-destructive detection method for portable plant nitrogen and moisture content provided by the present invention comprises: in the non-destructive detection system for field plant pigments of the present invention, the following steps are carried out:

1. First, turn on the power. The neutral reference sample 13 is placed between the light source 5 and the detector 6 by moving the sliding clamp 4;

2. The keyboard is operated, and the micro-controller 7 controls the wavelengths of the LED light sources in the 4-wavelength spectrum measuring device to output the detection light in 5 minutes, and the wavelengths are λ1=650-690nm, λ2=740-760nm, λ3=890-920nm, λ4 =960～980nm, after the detection light passes through the neutral reference sample, the photodetector 6 receives the original intensity I ₀₁ , I ₀₂ , I ₀₃ I ₀₄ 4 wavelengths of the light of each wavelength, and passes through the preamplifier 15 and the microcontroller The internal A/D analog-to-digital converter is input to the microcontroller 7;

3. Exit the neutral reference sample 13, and replace the fresh plant leaves 13 to be tested; place the leaves to be tested in the clips of the upper arm 2 and the lower arm 3 of the 4-wavelength spectrum measuring device, and manually open the clips during measurement After inserting the leaf, it will be automatically clamped by the force of the spring; repeat the steps of measuring the neutral reference sample, and measure the light intensity I of each wavelength passing through the fresh leaves of the plant, and the four wavelengths are I ₁ , I ₂ , I ₃ , and I ₄ , the output light is input to the microcontroller through pre-amplification and analog-to-digital converter;

4. The microcontroller uses the detected data (I ₀ and I of each wavelength) to calculate the transmittance T (T=I/I ₀ ) of each wavelength detection light to the fresh leaves of plants, and then use the following multiple linear equations The nitrogen level of plants in the leaves is calculated, and the result is displayed on the display screen. The system detection process is shown in Figure 4.

The set of equations described is as follows:

The content of chlorophyll in the leaves can be calculated by using the difference in the absorbance of the leaves to the No. 1 wavelength λ1 and the No. 2 wavelength λ2; the water content in the leaves can be calculated by using the difference in the absorbance of the leaves to the No. 3 wavelength λ3 and the No. 4 wavelength λ4:

Chlorophyll content Cchl in leaves (μg/cm ² )

Cchl=K1(A1-A2)+E1

Among them, A1 is the absorbance of leaves to λ1, A2 is the absorbance of leaves to λ2, K1 is a coefficient, K1 is equal to 10-40, and E1 is an error term.

Water content Cx in leaves (mg/cm ² )

Cx=K2(A4-A3)+E2

Among them, A4 is the absorbance of leaves to λ4, A3 is the absorbance of leaves to λ3, K2 is a coefficient, K2 is equal to 20-80, and E2 is an error term.

Plant nitrogen level NI can be calculated from the chlorophyll content C _Chl and water content C _x in leaves:

NI＝A*C _Chl +B*C _x

NI is plant nitrogen level; A is chlorophyll correlation coefficient (such as 1-1.5); B is moisture correlation coefficient (such as 0.5-0.8).

Multiple linear regression can also be used to establish the relationship between the absorbance of the leaves to the four wavelengths and the nitrogen nutrition level in the leaves, so as to calculate the nitrogen nutrition level of the leaves from the absorbance of the four wavelengths.

The non-destructive detection method and measuring instrument of portable plant nitrogen and moisture content provided by the present invention comprise: spectrum measuring device, it is characterized in that: also comprise a housing 12, keyboard 8 and liquid crystal display 9 are installed on the housing 12; A battery slot 11 for placing the working battery of the machine is set; and a system circuit board 16 is installed, and the system circuit board 16 is electrically connected to the microcontroller 7 by 4 road LED drive circuits 14 respectively, and the battery is connected to the 4 road LED drive circuits 14 Electrical connection; microcontroller 7 transmits data through serial port circuit 10; microcontroller 7 is electrically connected with keyboard 8 and liquid crystal display 9 installed on the casing 12; microcontroller 7 is electrically connected with light source 5 in the spectrum measuring device It is also electrically connected to the photodetector 6 through the preamplifier 15; the spectral measurement device has 4 wavelengths; it also includes: a blade clamp 1 for clamping the blade to be measured, and the blade clamp 1 is installed on the shell 12 In the upper arm 2 and the lower arm 3 of the blade clamp, 4 kinds of wavelength monochromatic light sources 5 for analysis and photodetectors 6 for analysis are relatively arranged, and there is a slideway on the blade clamp, and a slideway is installed for fixing the neutral light source. Referring to the sliding clamp 4 of the reference sample, a blade to be tested is placed between the light source and the detector of the blade clamp during measurement.

It also includes a computer, and the microcontroller 7 is electrically connected to the computer through a serial port circuit 10 .

In the above technical solution, the 4 kinds of wavelength monochromatic light source 5 adopts LEDs with 4 kinds of wavelengths, and its wavelength range is 650nm-1100nm; it includes: a combination of single-wavelength LED lamps, or a single-wavelength LED lamp containing at least 4 wavelengths Composite LED lights; and controlled by microcontroller 7 to work.

The system driving circuit can be made into a system circuit board with a microcontroller and a serial port circuit. The system driving circuit provides power for the light source, controls the work of the light source, collects the detection signal of the detector, and determines the center of the blade through signal processing. To be measured, the measurement results are displayed by the display 9; the work of the drive circuit board is controlled by the keyboard 8, and with a serial port circuit 10, it is also convenient to communicate with an external computer; the analog-to-digital converter is set inside the microcontroller (A/D converter).

In the above technical solution, the neutral reference sample is a sheet made of a material (such as ceramics, polytetrafluoroethylene, etc.) that has the same absorption effect on near-infrared light of each wavelength, and is used to detect The original intensity I ₀ (the four wavelengths are respectively I ₀₁ , I ₀₂ , I ₀₃ , and I ₀₄ ) is transmitted to the microcontroller (7). When measuring the leaves, withdraw the neutral reference sample, replace the fresh leaves of the plant and measure the light intensity I of each wavelength transmitted through the leaves (the four wavelengths are I ₁ , I ₂ , I ₃ , I ₄ ) and transmit it to the micro-controller The device 7 and the microcontroller 7 calculate the final result by using the I ₀ and I of each wavelength.

In the above-mentioned technical scheme, the detector is a semiconductor photodetector, which is placed in the lower arm of the blade clamp, and can also be placed in the upper arm of the blade clamp, to detect the original intensity I ₀ and the transmittance of each wavelength analysis light. After passing the intensity I of the blade, the detected signal is sent to the microcontroller, and after processing, it is determined that the blade is to be measured.

In the above technical solution, the display is a liquid crystal display or other displays for displaying analysis results and test parameters.

The advantages of the present invention are:

A portable non-destructive detection method and measuring instrument for plant nitrogen and water content of the present invention can measure the nitrogen content in living leaves, which improves the efficiency by dozens of times compared with the traditional chemical method of determination, and does not produce substances harmful to the environment; multi-wavelength The background effect and background component interference are corrected, and the non-destructive and accurate measurement of nitrogen content is solved. It can be widely used in crop diagnosis, breeding, agricultural production and scientific research.

1. This method is a direct measurement of living leaves in the field, without picking leaves and chemical pretreatment, and does not produce pollution. It is a green measurement method.

2. This method is a rapid measurement, which improves the efficiency by dozens of times compared with the traditional chemical method of determination.

3. Using at least 4 multiple wavelength combinations, correcting the background effect and eliminating background component interference.

4. It can well eliminate the influence of stray light in the field on the measurement.

5. The system adopts low power consumption design and is suitable for portability.

6. The measuring structure adopts sliding blade clamp, which is easy to use.

7. A solid neutral reference is selected, which solves the problem of matching the output light intensity of the light source with the detector.

8. The Chinese LCD is easy to use and can directly display the plant nitrogen level.

9. Data can be uploaded to PC.

Description of drawings

Fig. 1 is the non-destructive testing method and measuring instrument composition schematic diagram for plant nitrogen and moisture content of the present invention (dotted line among the figure represents the parts installed in the shell)

Fig. 2 is a schematic diagram of the composition of the 4-wavelength spectrum measuring device in the system of the present invention

Fig. 3 is a block diagram of the system driving circuit device of the present invention

Fig. 4 is a system detection flow chart of the present invention

Illustration

1—Blade Clamp 2—Blade Clamp Upper Arm 3—Blade Clamp Lower Arm

4—Neutral reference sample sliding clamp 5—Light source 6—Photoelectric detector

7—Microcontroller 8—Keyboard 9—Display

10—Serial port circuit 11—Battery slot 12—Shell

13—blade or neutral reference sample 14—four-way LED drive circuit 15—preamplifier

16—System Circuit Board

Detailed ways

With reference to accompanying drawing 1, develop a kind of portable plant nitrogen and the non-destructive measuring instrument of water content, comprise: a shell 12, one is installed on the shell 12 and is used to clamp the blade clamp 1 of blade to be measured; Described blade clamp It includes two parts, the upper arm 2 and the lower arm 3. The light source 5 for analysis and the photodetector 6 for analysis are arranged oppositely in the two arms. The photodetector is a PIN S6775 model purchased on the market; Slideway (not shown in the figure), neutral reference sample sliding clamp 4 is installed in the slideway, and the two slide fit; Shell 12 one wall is equipped with keyboard 8 and liquid crystal display 9; The battery slot 11 of the working battery of the machine, and the system circuit board 16; during detection, a blade to be tested or a neutral reference sample 13 is placed between the light source 5 and the photodetector 6 installed on the two arms.

With reference to accompanying drawing 2 and 3: shown system circuit device is made into a plate, comprises 4 road LED driver circuits 14, serial port circuit 10, and the micro-controller of the band A/D converter of the C8051F007 model that buys on the market The device 7 is made into a drive circuit board 16, and a system detection operation program is also solidified in the microcontroller 7, and its detection operation flow chart is shown in Figure 4; wherein the 4-way LED drive circuit 14 is connected with the microcontroller 7 of the C8051F007 model respectively. Electrically connected; the microcontroller 7 transmits data through the serial port circuit 10; the microcontroller 7 is electrically connected to the keyboard 8 and the liquid crystal display 9 installed on the casing 12; the microcontroller 7 is connected to the LED monochrome light source 5 with 4 wavelengths , its wavelength range is 600nm～1000nm; (or a composite LED lamp containing at least 4 wavelengths can be) electrically connected; it is also electrically connected to the PIN S6775 photodetector 6 through a TLC272 preamplifier 15, and the battery slot 11 The battery installed inside is electrically connected with the 4-way LED driving circuit 14 .

The detection light output by LED with 4 wavelengths is controlled by C8051F007 microcontroller 7. The detection light is visible—the near-infrared characteristic light is located on the plant leaves as the detection light source, and the PIN S6775 photoelectric detector is located on the neutral reference sample or fresh plant leaves. Next, it is used to detect the intensity I ₀ (four wavelengths I ₀₁ , I ₀₂ , I ₀₃ , I ₀₄ ) of the detection light of each wavelength after passing through the neutral reference sample or the intensity of the detection light of each wavelength after passing through the fresh leaves. Intensity I (4 wavelengths I ₁ , I ₂ , I ₃ , I ₄ ). Before measuring the leaves, a neutral reference sample was placed between the light source and the photodetector through a sliding clip to detect the original intensity I ₀ of each wavelength of light (4 wavelengths I ₀₁ , I ₀₂ , I ₀₃ , I ₀₄ ), Through the preamplifier TLC272, it enters the input terminal of the analog-to-digital converter of the microcontroller, converts it into a digital quantity and transmits it to the microcontroller. When measuring the leaves, withdraw the neutral reference sample, replace the fresh leaves of the plant and measure the light intensity I of each wavelength (4 wavelengths I ₁ , I ₂ , I ₃ , I ₄ ) passing through the leaves and transmit it to the microcontroller C8051F007. The microcontroller uses the detected data (I ₀ and I of each wavelength) to calculate the transmittance T (T=I/I ₀ ) of the detected light of each wavelength to the fresh leaves, and then uses the stoichiometric algorithm to calculate the plant nitrogen in the leaves The content of element, the calculation result is displayed on the display screen or transmitted data through the serial port circuit.

Apply the above-mentioned non-destructive testing method and measuring instrument for portable plant nitrogen and water content to measure the chlorophyll content in field plant leaves including rapeseed leaves, cabbage leaves, poplar leaves, and bean leaves. The specific steps are as follows:

1 First select the LED light source 5 with characteristic light of four wavelength bands, install it in the upper arm of the blade clamp 1, and install the photodetector 6 in the lower arm: the first wavelength band is expressed as 650-690nm by λ1, and the second The wavelength band is represented by λ2 as 740-760nm, the third wavelength band is represented by λ3 as 890-940nm; the fourth wavelength band is represented by λ4 as 960-980nm.

2. Turn on the power. The neutral reference sample 13 is placed between the light source 5 and the detector 6 by moving the sliding clamp 4;

3. Microcontroller 7 controls the wavelengths of light output by the light source in the multi-wavelength spectrum measurement device to be λ1=650～690nm, λ2=740～760nm, λ3=890～940nm, λ4=960～980nm, when the LED light source emits light respectively The detection light is received by the photodetector 6 after passing through the neutral reference sample, which is determined as the original intensity I ₀ of light of each wavelength (4 wavelengths I ₀₁ , I ₀₂ , I ₀₃ ), which is pre-amplified by 15 and simulated digital converter, input microcontroller 7;

4. Exit the neutral reference sample 13, and replace the fresh plant leaves 13 to be tested; place the leaves to be tested in the clips of the upper arm 2 and the lower arm 3 of the multi-wavelength spectrum measuring device, and manually open the clips during measurement. After entering the blade, it is automatically clamped by the force of the spring; the light intensity I of each wavelength (4 wavelengths I ₁ , I ₂ , I ₃ , I ₄ ) passing through the blade is measured and input to the micro-controller through the pre-amplification and analog-to-digital converter. device 7; wherein the neutral reference sample is made of a material with the same absorption effect on near-infrared light of each wavelength, made of ceramic or polytetrafluoroethylene sheet, and is used to detect the original intensity I ₀ ( 4 wavelengths I ₀₁ , I ₀₂ , I ₃ , I ₀₄ ) and input to microcontroller 7;

5. Microcontroller 7 utilizes the detected data (I ₀ and I of each wavelength) to calculate the transmittance T (T=I/I ₀ ) of each wavelength detection light to fresh leaves, and then utilizes the following multiple linear equations , using the stoichiometric algorithm to calculate the level of plant nitrogen in the leaves, and the results are displayed on the display.

The set of equations described is as follows:

The content of chlorophyll in the leaves can be calculated by using the difference in the absorbance of the leaves to the No. 1 wavelength λ1 and the No. 2 wavelength λ2; the water content in the leaves can be calculated by using the difference in the absorbance of the leaves to the No. 3 wavelength λ3 and the No. 4 wavelength λ4:

Chlorophyll content Cchl in leaves (μg/cm ² )

Cchl=K1(A1-A2)+E1

Among them, A1 is the absorbance of leaves to λ1, A2 is the absorbance of leaves to λ2, K1 is a coefficient, K1 is equal to 10-40, and E1 is an error term.

Water content Cx in leaves (mg/cm ² )

Cx=K2(A4-A3)+E2

Among them, A4 is the absorbance of leaves to λ4, A3 is the absorbance of leaves to λ3, K2 is a coefficient, K2 is equal to 20-80, and E2 is an error term.

Plant nitrogen level NI can be calculated from the chlorophyll content C _Chl and water content C _x in leaves:

NI＝A*C _Chl +B*C _x

NI is plant nitrogen level; A is chlorophyll correlation coefficient (such as 1-1.5); B is moisture correlation coefficient (such as 0.5-0.8).

Multiple linear regression can also be used to establish the relationship between the absorbance of the leaves to the four wavelengths and the nitrogen nutrition level in the leaves, so as to calculate the nitrogen nutrition level of the leaves from the absorbance of the four wavelengths.

Claims (6)

1. the lossless detection method of portable plant nitrogen and moisture is characterized in that may further comprise the steps:

A, at first starts power supply, and mobile slip clamp (4) is inserted neutral reference (13) between light source (5) and the photoelectric detector (6);

B, microcontroller (7) are controlled led light source (5) timesharing output detection light wavelength in the 4 wave spectrum measurement mechanisms respectively, its wavelength is λ 1=650～690nm, λ 2=740～760nm, λ 3=890～940nm, λ 4=960～980nm detects the green strength I that is received each wavelength light behind the neutral reference of light transmission by photoelectric detector (6) ₀₁, I ₀₂, I ₀₃I ₀₄, 4 wavelength place light intensities are through preposition amplification (15) and the inner set A/D analog-digital converter of microcontroller, input microcontroller (7);

C, neutral reference (13) is withdrawed from, change plant fresh leaves (13) to be measured; The blade that this blade to be measured is placed on described 4 wave spectrum measurement mechanisms presss from both sides clamping in (1), and repeating step B measures each the wavelength light intensity I that sees through plant fresh leaves to be measured ₁, I ₂, I ₃, I ₄, the analog-digital converter through preposition amplification and microcontroller inside, input microcontroller (7);

The data I that D, microcontroller (7) utilization are detected ₀With I, calculate each wavelength and detect the transmitance T=I/I of light fresh leaves ₀, utilize the multiple linear system of equations to calculate the relative content value M of reflection nitrogen level in the blade then, the result is shown by display screen;

E, the absorbance difference of No. 1 wavelength X 1 and No. 2 wavelength X 2 be can be regarded as out the blade content of chlorophyll with blade; The absorbance difference of No. 3 wavelength X 3 and No. 4 wavelength X 4 be can be regarded as out the content of moisture in the blade with blade:

Chlorophyll content Cchl (μ g/cm in the blade ²)

Cchl＝K1(A1-A2)+E1

Wherein A1 is the absorbance of blade to λ 1, and A2 is the absorbance of blade to λ 2, and K1 is a coefficient, and K1 equals 10～40, and E1 is an error term;

Moisture Cx (mg/cm in the blade ²)

Cx＝K2(A4-A3)+E2

Wherein A4 is the absorbance of blade to λ 4, and A3 is the absorbance of blade to λ 3, and K2 is a coefficient, and K2 equals 20～80, and E2 is an error term;

By blade content of chlorophyll C _ChlContent C with moisture _xCan calculate the horizontal NI of plant nitrogen:

NI＝A*C _chl+B*C _x

NI is the plant nitrogen level; A is chlorophyll related coefficient (as 1～1.5); B is moisture related coefficient (as 0.5～0.8);

Also can set up blade to containing the relational expression between the nitrogen trophic level in the absorbance of four wavelength and the blade, thereby calculate the nitrogen nutrition level of blade by the absorbance of four wavelength with multiple linear regression.

2, a kind of application rights requires the surveying instrument of the lossless detection method of 1 described portable plant nitrogen and moisture, comprise: spectral measurement device, it is characterized in that: also comprise a shell (12), keyboard (8) and LCD (9) are installed on the shell (12); One battery case (11) in order to lay this machine working battery is set in the shell (12); And installation system circuit board (16), this system circuit board (16) is electrically connected with microcontroller (7) respectively by 4 paths of LEDs driving circuits (14), and battery is electrically connected with 4 paths of LEDs driving circuits (14); Microcontroller (7) transmits data by serial port circuit (10); Microcontroller (7) is electrically connected with keyboard (8) and LCD (9) on being installed in shell (12); Microcontroller (7) is electrically connected with light source (5) in the spectral measurement device; Also be electrically connected with photoelectric detector (6) by prime amplifier (15); Described spectral measurement device has 4 wavelength; Also comprise the blade folder (1) that is used for clamping blade to be measured, blade folder (1) is installed on the shell (12); Be oppositely arranged 4 kinds of wavelength monochromatic sources (5) of analysis usefulness and photoelectric detector (6), its blade of analysis usefulness in the upper arm (2) of blade folder and the underarm (3) and have slideway on pressing from both sides, installation one is used for fixing the slip clamp (4) of neutral reference in the slideway.Leaf to be measured or neutral reference (13) are clamped by last underarm (2), (3), so that measure.

3. by the described surveying instrument of claim 2, it is characterized in that: also comprise a computing machine, microcontroller (7) electrically connects by serial port circuit (10) with computing machine.

4. by the described surveying instrument of claim 2, it is characterized in that: described neutral reference (13) is to use different wave length is had the thin slice that the neutral material of same absorbent effect is made, and this sheeting comprises pottery, teflon etc.

5. by the described surveying instrument of claim 2, it is characterized in that: described optical source wavelength scope is 600nm～1000nm; Comprise: single wavelength LED lamp is combined to form, or comprises the composite LED lamp of 4 wavelength.

6. by the described surveying instrument of claim 2, it is characterized in that: described photoelectric detector is a semi-conductor photodetector.

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