CN109991375B - Automatic measuring device for woody plant hydraulic structure and using method thereof - Google Patents

Abstract

The invention relates to an automatic measuring device of a woody plant hydraulic structure and a using method thereof, wherein the automatic measuring device comprises a multichannel measuring device, a pump valve executing mechanism, a data acquisition system, a weighing mechanism, a hydraulic conductivity measuring system and a computer control system; the multichannel measuring device comprises a public water pipeline, one end of the public water pipeline is connected with the water tank through a water inlet pipe, a plurality of channels to be measured are arranged at the other end of the public water pipeline side by side, and a weighing mechanism is respectively arranged at the lower end of each channel to be measured; the pump valve actuating mechanism is used for adjusting the pressure of liquid entering the public water pipeline and controlling the opening and closing of each channel to be tested; the data acquisition system is arranged at the inlet of the public water pipeline and is used for detecting the pressure of liquid entering the public water pipeline; the data collected by the weighing mechanism and the data collection system are sent to the computer control system through the hydraulic conductivity measuring system. The invention can be widely applied to the field of hydraulic structure measurement of woody plants.

Description

An automatic measuring device for the hydraulic structure of woody plants and its application method

technical field

The invention relates to the field of plant hydraulic structure research, in particular to a multi-channel woody plant hydraulic structure automatic measuring device suitable for ecological research and its use method. The device can measure the maximum hydraulic conductance, maximum Long conduit length and cavitation ratio in the natural state.

Background technique

The ability of the xylem of forest woody plants to transport water and resist cavitation may greatly affect the geographical distribution of plants and their ability to adapt to environmental stress, which is the main physiological and ecological cause of the death of large-scale forests worldwide in recent years due to extreme drought events one. Plant hydraulic conductance is an important part of plant hydraulic structure, which refers to the ability of plant water pipelines to transport water. Among them, plant water pipelines are mainly the conduit system of angiosperms and the sieve system of gymnosperms, and the length of the conduit is used as the anatomy of the conduit One of the characteristics, in the long-term evolution process, it meets the water transport needs of plants with its unique extreme geometry (great length/inner diameter ratio). The increase of conduit length is beneficial to improve the water transport efficiency, but it is more vulnerable to the threat of cavitation, so the conduit length is the neutralizing effect of the efficiency and safety of water transport in plants. The maximum hydraulic conductance of plants reflects the maximum water transport capacity of the non-embolized pipeline system, and is the core indicator of hydraulic structure research. It forms a multi-node regulatory network with other functional traits of plants, and jointly determines the water adaptation of species. Strategy. Regulation of hydraulic conductance and safety is one of the important functional traits for woody plants to maintain their internal water relationship. Under environmental stress, water in the xylem is under negative pressure during the process of plant water transport, and the water column in the vessel or tracheid breaks to cause cavitation, which leads to embolism and reduces the hydraulic conductivity. Different plants have different abilities to resist cavitation. Studies have shown that the cavitation ratio of xylem in the natural state is one of the important indicators of plant drought resistance. Therefore, under the changing environment, the hydraulic structure of plants is closely related to the adaptation strategies of species. Accurately measuring the longest vessel length of plants, the proportion of cavitation in the natural state, and the maximum hydraulic conductance are the prerequisites for studying the water relationship of plants.

Low-pressure liquid flow technology is currently the most commonly used method to quantitatively determine the hydraulic structure of xylem. Its principle is mainly to use a closed cover to cover the sample of the plant stalk or root to be tested. The upper end of the sample is connected with a certain height of washing solution, and the lower end is connected with a balance to measure and calculate the flow rate (hydraulic conductivity) of the washing solution after passing through the sample. ). The specific process is as follows: first, measure the quality of the flushing solution flowing through the water pipeline system per unit time with a 6kPa-10kPa flushing solution, and obtain the initial hydraulic conductivity Kx of the xylem; then use high air pressure to directly compress the flushing solution to increase its pressure to 110kPa~ 175kPa to drive out the cavitation in the embolized catheter; then use 6kPa～10kPa flushing solution to measure the mass of flushing fluid flowing through the water pipeline system per unit time, and calculate the maximum hydraulic conductivity; divide the initial hydraulic conductivity by the maximum hydraulic conductivity The conductance gives the cavitation ratio in the natural state.

As shown in Figure 1, it is a device that uses this method to measure initial hydraulic conductivity and maximum hydraulic conductivity in the prior art. 4', washing liquid container 5', three-way valve 6', plant sample to be tested 7', beaker 8', electronic balance 9' and computer 10'. This kind of device is the standard setting of the plant water relationship research laboratory. It uses the plant pressure chamber as the core and is equipped with external components to measure the maximum hydraulic conductivity of the plant. There is no commercialized instrument at present. However, this device has the following deficiencies: 1) there are many operating steps, and the branches need to be washed several times under different pressures, and the branches of different species require different washing pressures, so the operation process is too complicated; 2) the degree of automation is low, and testers are required Adjust the pressure of the pressure chamber and pressure tank at different steps, observe and record the pressure changes and balance readings at any time, so the measurement efficiency and accuracy depend on the technical proficiency of the testers; Large-scale research often collects a huge number of samples, and long-term storage of samples will lead to a decrease in physiological activity; therefore, when using this device to measure a large number of samples, the accuracy of the measurement results will decrease as the physiological activity of the sample to be tested decreases; as shown in Figure 4 As shown in Figure 5, the measurement of the hydraulic conductivity of the branches of poplar and Chinese pine at different times after picking shows that as time goes on, the hydraulic conductivity value gradually decreases; Even if it can be used, it will be limited by the large gas storage capacity and cannot measure samples in large quantities.

Contents of the invention

In view of the above problems, the object of the present invention is to provide an automatic measuring device for the hydraulic structure of woody plants and its use method, which can not only effectively improve the accuracy of the measurement results, but also can measure more than 10 branches at the same time, so as to achieve rapid and accurate determination of woody plants. The purpose of the maximum hydraulic conductance of this plant is to provide a powerful tool for studying important physiological and ecological issues such as the adaptation mechanism of plant hydraulic structure under adversity stress; Cavitation ratio.

In order to achieve the above object, the present invention adopts the following technical solutions: an automatic measuring device for the hydraulic structure of woody plants, which includes a multi-channel measuring device and a computer control system connected to the multi-channel measuring device, a hydraulic conductivity measuring system, A data acquisition system, a pump valve actuator and a weighing mechanism; the multi-channel measuring device includes a public water pipeline, one end of the public water pipeline is connected to the water tank through a water inlet pipe, and the connection between the public water pipeline and the water tank The pump and valve actuators are arranged on the water inlet pipe between them; the other end of the public water pipeline is provided with a plurality of channels to be tested for connecting with the plant samples to be tested, and each channel to be tested is provided with a The weighing mechanism; the computer control system sends a control signal to the pump valve actuator through the hydraulic conductivity measurement system to adjust the pressure of the liquid entering the public water pipeline, and at the same time control the The opening and closing of the channel; the data acquisition system respectively detects the pressure of the flushing solution entering the public water pipeline and the weight data of the weighing mechanism, and sends them to the computer through the hydraulic conductivity measurement system Control System.

Further, the pump and valve actuators include first to third actuators; the first actuator includes a pressurizing pump, a pressure stabilizing pump, a pressurizing valve and a pressure stabilizing valve, and the boosting pump and the stabilizing pump The inlet of the pump is connected in parallel with the outlet of the water tank, and the outlet of the booster pump and the pressure stabilizing pump are connected in parallel with the inlet of the public water pipeline; the pressurizing valve and the pressure stabilizing valve are respectively arranged in the The outlet ports of the pressurizing pump and the stabilizing pump are used to adjust the pressure at the outlet ports of the pressurizing pump and the stabilizing pump; the second actuator includes a plurality of channel solenoid valves, and each channel solenoid valve is respectively arranged on each The end of the channel to be tested is used to control the opening and closing of each channel to be tested; the third actuator includes a pressure relief valve, and the pressure relief valve is arranged at the end of the public water pipeline; the The pressurizing valve, the pressure stabilizing valve, the pressure relief valve and each channel valve are respectively connected with the hydraulic conductance measuring system through control lines.

Further, the rated power of the booster pump is 120W, the head is 12m-15m, the flow rate is 1L/Min, the inner diameter is 15mm, and the pressure control range is 0-300KPA.

Further, the power of the pressure stabilizing pump is 3W, the head is 1m-2m, the flow rate is 0.3L/Min, the inner diameter is 2mm, and the pressure control range of the pressure stabilizing pump is 0-200KPA.

Further, the power of the channel electromagnetic valve is 4.8W, the pressure range is -0.15MPa-0.8MPa, and it is controlled by a normally closed electromagnetic switch.

Further, the weighing mechanism includes a beaker and a weighing unit, the beaker is placed on the weighing unit, and the mouth of the beaker is facing the plant sample to be tested connected to the channel to be tested.

Further, the data acquisition system includes a pressure data acquisition control unit, a weighing data acquisition control unit, and a data transmission and storage unit; the pressure data acquisition control unit adopts a pressure sensor, and the pressure sensor is set in the public water supply The water inlet of the pipeline, the pressure data collected by the pressure sensor is sent to the computer control system through the hydraulic conductivity measurement system; Perform control and data collection, and send to the computer control system for processing and display; the data collection and storage unit is used to transmit and store all data.

Further, the pressure sensor has a pressure range of 0-700KPa and a sensitivity of 0.1KPa.

A method for using an automatic measuring device for a woody plant hydraulic structure, comprising the following steps:

1) select the plant sample to be tested;

2) After removing the air bubbles in the channel to be tested of the measuring device, subtract 2 cm from both ends of the plant sample to be tested in water, and install the plant sample to be tested at the end of the channel to be tested in water;

3) After the installation of the plant sample to be tested is completed, if the longest conduit length of the plant sample to be tested needs to be measured, then enter step 4), if it is necessary to measure the cavitation degree of the plant sample to be tested in a natural state, then enter Step 5), if the maximum hydraulic conductivity of the plant sample to be tested needs to be measured, then enter step 6);

4) Turn on the pressure stabilizing pump and the stabilizing valve, use 6kpa low pressure to wash the branches, and repeat the pruning under water until the air bubbles evenly emerge from the center of the plant sample to be tested. At this time, the length of the plant sample to be tested is the longest tube length;

5) Connect the installed plant sample to be tested to the corresponding weighing unit, wash the plant sample to be tested with 6kpa low pressure, record the weight of dripping water, and end the measurement after the data is stable, and calculate the natural state according to the low flow rate at this time. The hydraulic conductance, which is divided by the maximum hydraulic conductance, is the cavitation ratio;

6) Connect the installed plant sample to be tested to the corresponding weighing unit, and start high-pressure washing: according to the needs of the plant sample to be tested, determine the pressure range to be 210kPa ~ 275kPa, high-pressure wash for 3 minutes, stop for 2 minutes, repeat 3 Second, completely remove the cavitation inside the water delivery pipe of the plant sample to be tested; after the high-pressure flushing is completed, measure the maximum hydraulic conductivity: open the pressure relief valve to relieve the pressure to the required measurement pressure of the plant sample to be tested, and turn on the pressure stabilizing pump Keep the pressure stable with the pressure stabilizing valve; operate the weighing unit to zero, wait for the zeroing to complete, start timing measurement, and end the measurement after the data is stable.

Further, in the step 2), the method for removing the air bubbles in the channel of the measuring device to be tested is as follows: open the computer control system, the computer control system determines the pressure value according to the requirements of different test items, and sends out the opening of the booster pump and pressurization Valve command, after the pump valve control unit in the hydraulic conductance measurement system receives the command, it sends a command to the booster pump and the booster valve and executes it. The flushing solution in the tank starts to flow from the water inlet pipe to the public water pipeline. At this time The pressure sensor collects the pressure at the inlet of the public water pipeline, and sends it to the computer control system for display through the hydraulic conductivity measurement system; before installing the plant sample to be tested, turn on the booster pump and the booster valve, and adjust the pressure value to 300kPa or Above, the air bubbles in the channel to be tested are completely removed.

Because the present invention adopts the above technical scheme, it has the following innovations: 1. The present invention uses multi-channel simultaneous pressurized flushing, simultaneous measurement, and simultaneous data collection and transmission, and the software automatically calculates the hydraulic conductance and The maximum hydraulic conductance value is fully automated, and is suitable for ecological large-scale and large-scale sample hydraulic structure research; 2. The present invention uses pulse modulation technology (PWM) to control the voltage of the pressure pump, thereby controlling the speed of the pump. Finally, by controlling The pressure is controlled by the flow of water to achieve the purpose of precisely controlling the flow rate of water passing through the branches, which can effectively improve the accuracy of the measurement results. 3. The present invention polls 10 weighing modules at the millisecond level for control and data collection and sends them to the computer software. The computer software displays weight changes in real time, and can store and output them, effectively improving the hydraulic conductivity measurement efficiency. 4. Since the present invention is equipped with a pressurizing pump and a stabilizing pump to directly pressurize the branch to be tested, it does not rely on high-pressure gas to control the pressure, so it is very suitable for measuring in the field. 5. The present invention is easy to operate when used, and has high reliability. It can also quickly measure the longest conduit length of branches and the cavitation ratio of xylem in the natural state. Therefore, it can be widely used in the study of plant hydraulic structure and has significant social significance. benefit, economic benefit and ecological benefit.

Description of drawings

Fig. 1 is the connection schematic diagram of measuring maximum hydraulic conductance in the prior art;

Fig. 2 is a structural representation of the present invention;

Fig. 3 is a schematic diagram of device connection of the present invention;

Fig. 4 is poplar maximum hydraulic conductance in the embodiment of the present invention along with measuring time change figure;

Fig. 5 is that the maximum hydraulic conductance of pine trees varies with the measurement time in the embodiment of the present invention;

The markings in the figure are as follows: 1. Water tank; 2. Booster pump; 3. Regulatory pump; 4. Booster valve; 5. Regulatory valve; 6. Public channel; 7. Control line; 8. Pressure relief valve; 9. Hydraulic conductivity measurement system; 10. Solenoid valve; 11. Beaker; 12. Weighing unit; 13. Pressure sensor; 14. Computer control system.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 2 and Fig. 3, a kind of automatic measuring device of woody plant hydraulic structure provided by the present invention comprises a multi-channel measuring device and a computer control system connected to the multi-channel measuring device, a hydraulic conductance measuring system, data Acquisition system, pump valve actuator and weighing mechanism. Wherein, the multi-channel measurement device includes a public water delivery pipeline 6, one end of the public water delivery pipeline 6 is connected to the water tank 1 through a water inlet pipe, and a pump valve actuator is arranged on the water inlet pipe between the public water delivery pipeline and the water tank; The other end of the pipeline 6 is provided side by side with a plurality of channels to be tested for connection with the plant samples to be tested, and a weighing mechanism is respectively set under each channel to be tested; the computer control system sends control signals to the pump valve through the hydraulic conductance measurement system. The mechanism adjusts the pressure of the liquid entering the public water pipeline 6, and at the same time controls the opening and closing of each channel to be tested; the data acquisition system respectively detects the pressure of the flushing solution entering the public water pipeline 6 and the weight data of the weighing mechanism , and sent to the computer control system through the hydraulic conductivity measurement system.

Preferably, as shown in FIG. 3 , the pump valve actuator includes first to third actuators, and the first actuator includes a pressurizing pump 2, a pressure stabilizing pump 3, a pressurizing valve 4 and a stabilizing valve 5, wherein the pressurizing After the inlets of the pressure pump 2 and the pressure stabilizing pump 3 are connected in parallel, the outlet of the water tank 1 is connected through the water inlet pipe; The pressure stabilizing valve 5 is arranged at the outlet ports of the pressurizing pump 2 and the stabilizing pump 3 respectively, and is used to regulate the pressure at the outlet ports of the pressurizing pump 2 and the stabilizing pump 3; the second actuator includes a plurality of channel solenoid valves 10, Each channel solenoid valve 10 is respectively arranged at the end of each channel to be tested, and is used to control the opening and closing of each channel to be tested, and then control the water flow of each channel to be tested to enter the plant sample to be tested; the third actuator includes a pressure relief valve 8, The pressure relief valve 8 is arranged at the end of the public water delivery pipeline 6; the pressurizing valve 4, the pressure stabilizing valve 5, the pressure relief valve 8 and the solenoid valves 10 of each channel are respectively connected to the hydraulic conductance measuring system 9 through the control line 7, and the hydraulic conductivity The conductance measuring system 9 is connected with the computer control system 14 and is controlled by the computer control system 14 .

Preferably, the rated power of the booster pump 2 is 120W, the head is 12m-15m, the flow rate is 1L/Min, the inner diameter is 15mm, and the pressure control range of the booster pump 2 can be adjusted arbitrarily between 0-300KPA.

Preferably, the rated power of the stabilizing pump 3 is 3W, the head is 1m-2m, the flow rate is 0.3L/Min, the inner diameter is 2mm, and the pressure control range of the stabilizing pump can be adjusted arbitrarily between 0-200KPA.

Preferably, the channel solenoid valve 10 has a power of 4.8W, a pressure range of -0.15MPa-0.8MPa, and is controlled by a normally closed solenoid switch.

Preferably, the weighing mechanism includes a beaker 11 and a weighing unit 12, the beaker 11 is placed on the weighing unit 12, and the mouth of the beaker 11 faces the plant sample to be tested connected to the measurement channel.

Preferably, the measuring range of the weighing unit 12 is 220g, the precision is 0.0001g, and every 4 weighing units is a group. Each weighing unit 12 has its own processor system, capable of weighing changes in the weight of the beaker 11 in real time.

Preferably, the data acquisition system includes a pressure data acquisition control unit, a weighing data acquisition control unit, and a data transmission and storage unit. The pressure data acquisition control unit adopts pressure sensor 13, and this pressure sensor 13 is arranged on the water inlet of public water pipeline 6, and the pressure data that pressure sensor 13 collects is sent to computer control system 14 by hydraulic conductance measurement system 9; Weighing data acquisition The control unit is used to control and collect data from each weighing mechanism according to the preset period (the preset period can reach millisecond level), and send it to the computer control system 14 for processing and display through the hydraulic conductance measurement system 9; the data acquisition and The storage unit is used to transmit and store all data.

Preferably, the computer control system uses pulse modulation technology (PWM) to control the voltage of the booster pump and the voltage regulator pump, thereby controlling the speed of the booster pump and the regulator pump, and finally controls the pressure by controlling the flow of water to realize pressure control automation , to achieve the purpose of precisely controlling the pressure and maintaining it for a long time.

Preferably, the pressure range of the pressure sensor 13 is 0-700KPa, and the sensitivity is 0.1KPa.

Preferably, the plant sample to be tested is the stem, branch or root of a woody plant.

Preferably, the connecting pipe adopts a transparent and smooth silicone soft water pipe.

Based on the above-mentioned automatic measuring device for the hydraulic structure of woody plants, the present invention also provides a method for using the automatic measuring device for the hydraulic structure of woody plants, which includes the following test items:

A) Automated determination of longest catheter length

(1) Open the computer control system 14, and the computer control system 14 determines the pressure value according to the requirements of different test items such as system debubbling, sample high-pressure flushing, and low-pressure measurement, and sends an order to open the pressurization pump and pressurization valve through the RS232 communication interface. After the pump valve control unit in the conductance measurement system receives the command, it sends and executes the command to the booster pump and the booster valve, and the flushing solution in the tank starts to flow from the water inlet pipe to the public water pipeline 6. At this time, the pressure sensor 13 The pressure at the inlet of the public water pipeline 6 is collected and sent to the computer control system 14 for display through the hydraulic conductance measurement system 9 .

(2) Before installing the plant sample to be tested, turn on the pressurization pump 2 and pressurization valve 4, adjust the pressure value to 300kPa or above, completely remove the air bubbles in the channel to be tested, and then connect the plant sample to be tested to the test channel On the water outlet of the channel, continue the follow-up operation.

(3) Cut the terminal branches of 2-5 years old as the plant samples to be tested. The length should be more than twice the length of the longest tube and the diameter is about 5-8mm. Cover it with wet gauze and bring it back to the laboratory for measurement immediately;

(4) After removing the air bubbles in the channel to be tested of the measuring device, subtract 2 cm from both ends of the plant sample to be tested in water, and install the plant sample to be tested on the channel to be tested in water;

(5) After the installation of the plant sample to be tested is completed, open the stabilizing pump 3 and the stabilizing valve 5, use low pressure (6kpa) to rinse the branches, and repeat the pruning under water until the air bubbles evenly emerge from the center of the plant sample to be tested, The length at this point is the longest catheter length. Since the device can measure more than 10 branches at the same time, the work efficiency is undoubtedly greatly improved for the ecological field investigation.

B) Automatic determination of the degree of cavitation in the natural state

(1) Repeat steps (1) and (2) in A);

(2) Cut off 2-5-year-old terminal branches as the plant samples to be tested, whose length is 1.5 times the length of the longest tube and about 5-8mm in diameter, wrap them in wet gauze and bring them back to the laboratory for testing immediately;

(3) After removing the air bubbles in the channel to be tested of the measuring device, subtract 2 cm from both ends of the plant sample to be tested in water, and install the plant sample to be tested on the channel to be tested in water;

(4) Connect the installed plant sample to be tested to the corresponding weighing unit, use low pressure (6kpa) to rinse the branches, record the weight of the dripping water, and end the measurement after the data is stable.

(5) Calculate the hydraulic conductance in the natural state according to the low flow rate at this time, and divide the conductance by the maximum hydraulic conductance, which is the cavitation ratio.

(6) It is also possible to directly wash the branches with low pressure (6kpa) after performing A, calculate the hydraulic conductance in the natural state, and then divide it by the maximum hydraulic conductance to obtain the cavitation ratio in the natural state.

C) Automatic determination of maximum hydraulic conductance

(1) Repeat steps (1) and (2) in A;

(2) Cut the 2-5-year-old terminal branch of the plant sample to be tested, the length is 1.5 times the length of the longest tube, and the diameter is about 5-8mm, and immediately take it back to the laboratory for measurement with wet gauze;

(1) After removing the air bubbles in the channel to be tested of the measuring device, subtract 2 cm from both ends of the plant sample to be tested in water, and install the plant sample to be tested on the channel to be tested in water;

(3) Connect the installed plant sample to be tested to the corresponding weighing unit, and start high-pressure washing. According to the needs of the samples to be tested, adjust the pressure range from 210kPa to 275kPa (usually the required pressure difference is 110kPa to 175kPa), high-pressure flushing for 3 minutes, stop for 2 minutes, and repeat 3 times to completely remove the cavitation inside the branch water pipe.

(4) After the high-pressure flushing is completed, the maximum hydraulic conductance measurement is started. Open the pressure relief valve to release the pressure to the required measurement pressure of the sample to be tested, usually 106-110kPa (the required pressure difference is 6-10kPa), and open the pressure stabilizing pump and the pressure stabilizing valve to keep the pressure stable.

(5) Start the zeroing operation of the weighing unit, wait for the zeroing to be completed, and start timing measurement. End the measurement after the data is stable, and the measurement time depends on the sample, generally 15min.～30min.

The foregoing embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component can be changed to some extent, and any equivalent transformation and improvement carried out on the basis of the technical solution of the present invention should not be excluded. Outside the protection scope of the present invention.

Claims (9)

1. An automatic measuring device of woody plant hydraulic structure which characterized in that: the system comprises a multichannel measuring device, a computer control system, a hydraulic conductivity measuring system, a data acquisition system, a pump valve executing mechanism and a weighing mechanism, wherein the computer control system, the hydraulic conductivity measuring system, the data acquisition system, the pump valve executing mechanism and the weighing mechanism are connected with the multichannel measuring device;

the multichannel measuring device comprises a public water pipeline, one end of the public water pipeline is connected with a water tank through a water inlet pipe, and the pump valve executing mechanism is arranged on the water inlet pipe between the public water pipeline and the water tank;

the other end of the public water pipeline is provided with a plurality of channels to be tested which are used for being connected with plant samples to be tested, and a weighing mechanism is respectively arranged below each channel to be tested;

the computer control system sends a control signal to the pump valve executing mechanism through the hydraulic conductivity measuring system to regulate the pressure of liquid entering the public water pipeline and simultaneously control the opening and closing of each channel to be measured;

the data acquisition system detects the pressure of the flushing solution entering the public water pipeline and the weight data of the weighing mechanism respectively, and sends the pressure data and the weight data to the computer control system through the hydraulic conductivity measuring system;

the pump valve executing mechanism comprises first to third executing mechanisms;

the first actuating mechanism comprises a pressure pump, a pressure stabilizing pump, a pressure valve and a pressure stabilizing valve, wherein the inlets of the pressure pump and the pressure stabilizing pump are connected in parallel and then connected with the outlet of the water tank, and the outlets of the pressure pump and the pressure stabilizing pump are connected in parallel and then connected with the inlet of the public water pipeline; the pressurizing valve and the pressure stabilizing valve are respectively arranged at the outlet ends of the pressurizing pump and the pressure stabilizing pump, and the pressures of the pressurizing pump and the pressure stabilizing pump outlet ends are regulated;

the second executing mechanism comprises a plurality of channel electromagnetic valves, and each channel electromagnetic valve is respectively arranged at the tail end of each channel to be detected and used for controlling the opening and closing of each channel to be detected;

the third actuating mechanism comprises a pressure release valve which is arranged at the tail end of the public water pipeline;

the pressurizing valve, the pressure stabilizing valve, the pressure releasing valve and the channel valves are respectively connected with the hydraulic conductivity measuring system through control lines, and the computer control system controls the voltage and the rotating speed of the pressurizing pump and the pressure stabilizing pump by adopting a pulse modulation technology.

2. An automated measurement device for the hydraulic structure of woody plants as set forth in claim 1, wherein: the rated power of the booster pump is 120W, the lift is 12 m-15 m, the flow is 1L/Min, the inner diameter is 15mm, and the pressure control range is 0-300 KPA.

3. An automated measurement device for the hydraulic structure of woody plants as set forth in claim 1, wherein: the power of the pressure stabilizing pump is 3W, the lift is 1 m-2 m, the flow is 0.3L/Min, the inner diameter is 2mm, and the pressure control range of the pressure stabilizing pump is 0-200 KPA.

4. An automated measurement device for the hydraulic structure of woody plants as set forth in claim 1, wherein: the power of the channel electromagnetic valve is 4.8W, the pressure range is-0.15 MPa-0.8 MPa, and the channel electromagnetic valve is in a normally closed electromagnetic switch control mode.

5. An automated measurement device for the hydraulic structure of woody plants as set forth in claim 1, wherein: the weighing mechanism comprises a beaker and a weighing unit, the beaker is placed on the weighing unit, and the beaker opening is opposite to the plant sample to be measured, which is connected with the channel to be measured.

6. An automated measurement device for the hydraulic structure of woody plants as set forth in claim 1, wherein:

the data acquisition system comprises a pressure data acquisition control unit, a weighing data acquisition control unit and a data transmission and storage unit;

the pressure data acquisition control unit adopts a pressure sensor, the pressure sensor is arranged at the water inlet of the public water pipeline, and the pressure data acquired by the pressure sensor is sent to the computer control system through the hydraulic conductivity measuring system;

the weighing data acquisition control unit is used for controlling and data acquisition of each weighing mechanism according to a preset period and sending the weighing mechanism to the computer control system for processing and displaying;

the data transmission and storage unit is used for transmitting and storing all data.

7. An automated measurement device for the hydraulic structure of woody plants as set forth in claim 6, wherein: the pressure range of the pressure sensor is 0-700 KPa, and the sensitivity is 0.1KPa.

8. A method of using the automated measurement device for hydraulic structures of woody plants according to any one of claims 1 to 7, characterized in that it comprises the following steps:

1) Selecting a plant sample to be detected;

2) Removing bubbles in a channel to be measured of a measuring device, subtracting 2cm from two ends of a plant sample to be measured in water, and installing the plant sample to be measured at the tail end of the channel to be measured in water;

3) After the plant sample to be measured is installed, if the longest conduit length of the plant sample to be measured is required to be measured, the step 4) is carried out, if the cavitation degree of the plant sample to be measured in a natural state is required to be measured, the step 5) is carried out, and if the maximum hydraulic conductivity of the plant sample to be measured is required to be measured, the step 6) is carried out;

4) Opening a pressure stabilizing pump and a pressure stabilizing valve, flushing branches by adopting 6kpa low pressure, and repeatedly pruning under water until bubbles are seen to uniformly emerge from the center of a plant sample to be tested, wherein the length of the plant sample to be tested at the moment is the length of the longest conduit;

5) Connecting the installed plant sample to be measured to a corresponding weighing unit, flushing the plant sample to be measured by adopting 6kpa low pressure, recording the dripping weight, ending the measurement after the data is stable, calculating the hydraulic conductivity in a natural state according to the low flow rate at the moment, and dividing the hydraulic conductivity by the maximum hydraulic conductivity to obtain cavitation proportion;

6) The installed plant sample to be measured is connected to a corresponding weighing unit, and high-pressure flushing is started: determining that the pressure adjusting range is 210 kPa-275 kPa according to the needs of the plant sample to be detected, flushing at high pressure for 3min, stopping for 2min, repeating for 3 times, and completely removing cavitation in the water pipe of the plant sample to be detected; after the high-pressure flushing is finished, the maximum hydraulic conductivity measurement is carried out: opening a pressure relief valve to relieve the pressure to the measured pressure required by the plant sample to be measured, and opening a pressure stabilizing pump and a pressure stabilizing valve to keep the pressure stable; and (3) carrying out zero resetting operation on the symmetrical weight unit, waiting for zero resetting to be finished, starting timing measurement, and ending the measurement after the data are stable.

9. The method of using an automated measurement apparatus for hydraulic structures of woody plants according to claim 8, wherein: in the step 2), the method for removing bubbles in the channel to be measured of the measuring device comprises the following steps:

opening a computer control system, determining pressure values according to different test item requirements, sending out commands for opening a pressurizing pump and a pressurizing valve, sending commands to the pressurizing pump and the pressurizing valve after a pump valve control unit in the hydraulic conductivity measuring system receives the commands, and executing the commands, wherein flushing solution in a water tank starts to flow from a water inlet pipe to a public water pipeline, and at the moment, a pressure sensor collects the pressure of an inlet of the public water pipeline and sends the pressure to the computer control system for display through a hydraulic conductivity measuring system;

before installing the plant sample to be tested, opening a pressurizing pump and a pressurizing valve, adjusting the pressure value to 300kPa or more, and thoroughly removing bubbles in the channel to be tested.

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