A system and method for monitoring plant root exudates in situ

Abstract

This invention discloses a system and method for in-situ monitoring of plant root exudates. The system includes a collector, a filtration flask, a drying flask, and a vacuum pump. Under continuous negative pressure from the vacuum pump, the liquid from the plant roots in the collector enters the filtration flask through a silicone tube. The collector has a built-in sensor probe connected to an external temperature and humidity detector, and the filtration flask has a built-in thermal effect biosensor. The thermal effect biosensor is signal-connected to a temperature control module, which in turn is signal-connected to a signal acquisition and processing module. The signal acquisition and processing module converts the conducted thermal signal into an electrical signal, which is compared with a standard curve. The content of each component in the plant root exudate is determined by the curve peaks. This invention eliminates the need for rapid filtration using a pore membrane after the plant root exudate collection is completed. The operation is simple and fast, and the migration components and total amount of organic matter change minimally, reflecting the real-time state of the exudate.

Description

Technical Field

[0001] This invention belongs to the field of plant science, and in particular relates to a system and method for in situ monitoring of plant root exudates. Background Technology

[0002] Root exudate research is an important area of ​​study in plant science, aiming to gain a deeper understanding of the interactions and regulatory mechanisms between plant roots and their surrounding environment. Root exudates are chemical substances secreted by plant root cells and tissues into the rhizosphere environment, mainly including carbohydrates, amino acids, organic acids, enzymes, and other compounds. They play a crucial role in plant growth and development, nutrient absorption, stress responses, and interactions between soil animals and microorganisms. With the deepening research in plant physiology and plant ecology, it has been found that the study of root exudates helps to understand the mechanisms of plant-environment interaction and provides a scientific basis for plant growth regulation, soil improvement, and sustainable agricultural development.

[0003] Methods for detecting root exudates mainly rely on analyzing the chemical components or active substances within them. The exploration of root exudate collection methods has a history of decades in botany and soil science. Among these, rhizosphere sap collection methods are widely used due to their advantages such as non-destructiveness, real-time availability, high sample quality, repeatability, quantification, simplicity, and ease of control. Common collection methods include rhizosphere sap adsorption, adsorption resin methods, adsorption filter paper methods, and rhizosphere sap samplers. In the collection process, rhizosphere sap adsorption, adsorption resin, and adsorption filter paper methods involve placing hydrophilic materials around the soil, adsorbing the rhizosphere sap onto the materials, and then eluting and analyzing it with a suitable solvent. Rhizosphere sap samplers, on the other hand, use specially designed rhizosphere sap samplers buried in the soil, with their channels in contact with the plant roots. Typically, after a certain period, the sampling channel of the sampler is opened to collect rhizosphere sap samples for observation. The rhizosphere sap collection device used varies depending on the specific object being observed (vegetation type, growth characteristics, etc.). Many existing in-situ root exudate monitoring devices consume a lot of time in the collection and separation testing process, which can easily alter the organic components in the exudate, making it impossible to guarantee the reliability and accuracy of the detection. Summary of the Invention

[0004] To overcome the shortcomings and deficiencies of the prior art, the present invention aims to provide a system and method for in-situ monitoring of plant root exudates.

[0005] This invention is implemented as follows: a system for in-situ monitoring of plant root exudates. The system includes a plant root exudate collector, a filtration flask, a drying flask, and a vacuum pump. Under the continuous negative pressure of the vacuum pump, the liquid from the plant roots in the collector enters the filtration flask through a silicone tube; wherein... The collector has a built-in sensor probe for an external temperature and humidity detector, and the filtration flask has a built-in thermal effect biosensor. The thermal effect biosensor is connected to the temperature control module, and the temperature control module is connected to the signal acquisition and processing module. The signal acquisition and processing module is used to convert the conducted thermal signal into an electrical signal, which is compared with a standard curve. The content of each component in the plant root exudate is determined by the curve peak.

[0006] Preferably, the thermal effect biosensor includes a support rod, a thermal effect detection element is fixed at the end of the support rod, and a heat transfer medium coating is applied to the support rod. The end of the support rod and the thermal effect detection element are placed inside a vacuum filtration flask. The thermal effect detection element is one of a thermistor, a thermocouple, and a resistance temperature detector.

[0007] Preferably, the collector includes a bottle body with an interface for connecting a silicone tube at the bottom. The top opening of the bottle body is sealed with a cap. The cap has a through hole for adding plant roots into the bottle body, an adjustment ring for adjusting the size of the through hole, and an injection hole at the edge of the cap. An injection tube for adding nutrient solution into the bottle body is inserted into the injection hole. The bottom of the bottle body is lined with glass wool, and glass stones are filled and covered on the glass wool, with plant roots inserted into the glass stones.

[0008] Preferably, the inlet of the filtration flask is equipped with a filter.

[0009] This invention further discloses a method for in-situ monitoring of plant root exudates using the above-described system, the method comprising the following steps: (1) Add the disinfected glass wool and glass stone into the collector, insert the sensor probe of the external temperature and humidity detector, and tighten the cap. (2) Select the plant roots to be monitored and clean them in situ. Insert the cleaned plant roots into the collector through the through hole of the cap and adjust the collector so that the plant roots are inserted into the glass stone. (3) By inserting an injection tube into the cap of the collector, the nutrient solution is injected into the injection tube, and the vacuum pump is turned on. The nutrient solution is used to clean the collector and the filtration flask in sequence. (4) Inject nutrient solution through the injection tube and bury the collector in the soil for 24 hours to allow it to equilibrate. (5) After equilibration, the secretion collection liquid in the collector is pumped into the filtration flask by a vacuum pump, and the same amount of nutrient solution is added through the injection tube. The corresponding temperature and humidity are recorded. (6) The heat change of the secretion collection liquid is monitored in the vacuum filtration flask by a built-in thermal effect biosensor; (7) The monitoring data of the thermal effect biosensor is converted, stored, analyzed and imaged by computer, and the content of each component in the plant root exudate is determined by the curve peak.

[0010] Compared with the shortcomings and deficiencies of existing technologies, the present invention has the following beneficial effects: (1) This invention can measure the root secretion of a single target plant, eliminate soil interference, and the observation results are reliable and accurate; (2) The collection and analysis of plant root exudates in this invention are completed in a sealed environment and are not affected by soil infiltration on the sampling results; (3) This invention avoids the need for manual removal of the sampler from the soil and liquid replacement after plant cultivation, effectively eliminating experimental errors; (4) After the plant root exudates are collected, there is no need to filter them with a pore membrane and follow up with subsequent processes as soon as possible. The operation steps are simple and fast, and the migration components and total amount of organic matter change little, which can reflect the real-time status of the exudates. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the system structure of the present invention; Figure 2 These are three views of the collector in the system of this invention; Figure 3 This is an exemplary ammonia nitrogen content monitoring change curve in an embodiment of the present invention; Figures 1-2 In the middle, there are: collector 1, filtration flask 2, drying flask 3, vacuum pump 4, temperature and humidity detector 5, sensing probe 6, thermal effect biosensor 7, temperature control module 8, signal acquisition and processing module 9, filter 10, bottle body 1-1, interface 1-2, cap 1-3, through hole 1-4, adjusting ring 1-5, injection hole 1-6, injection tube 1-7, glass stone 1-8. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0013] This invention discloses a system for in-situ monitoring of plant root exudates, such as... Figure 1As shown, the system includes a plant root exudate collector 1, a filtration flask 2, a drying flask 3, and a vacuum pump 4. Under the continuous negative pressure of the vacuum pump 4, the liquid in the collector 1 enters the filtration flask 2 through a silicone tube. The collector 1 has a built-in sensor probe 6 connected to an external temperature and humidity detector 5, and the filtration flask 2 has a built-in thermal effect biosensor 7. The thermal effect biosensor 7 is signal-connected to a temperature control module 8, and the temperature control module 8 is signal-connected to a signal acquisition and processing module 9. The signal acquisition and processing module 9 is used to convert the conducted thermal signal into an electrical signal, which is compared with a standard curve to determine the component content through the curve peak.

[0014] In this embodiment of the invention, collector 1 is used for the growth of plant roots and the secretion of root exudates, which include bioactive substances, nutrients, and metabolites. The sensing probe 6 of the temperature and humidity detector 5 monitors the temperature and humidity within collector 1 to obtain more data for the experiment.

[0015] In this embodiment of the invention, the plant roots grow and secrete within the sealed, soil-isolated environment of the collector 1, and are not affected by soil infiltration on the sampling results. In addition, the liquid in the collector 1 can directly enter the filtration bottle 2, eliminating the need for manual removal of the sampler from the soil for liquid replacement, thus effectively eliminating experimental errors.

[0016] In this embodiment of the invention, in order to prevent impurities from entering the filtration flask 2, the inlet of the filtration flask 2 is provided with a filter 10.

[0017] In this embodiment of the invention, to create the environment required for plant root growth in collector 1, the invention provides a preferred implementation method, specifically, as follows: Figure 2As shown, the collector 1 includes a bottle body 1-1, with an interface 1-2 at the bottom of the bottle body 1-1 for connecting to a silicone tube. The top opening of the bottle body 1-1 is sealed by a cap 1-3. The cap 1-3 has a through hole 1-4 for adding plant roots into the bottle body 1-1. The cap 1-3 also has an adjusting ring 1-5 for adjusting the diameter of the through hole 1-4. The adjusting ring 1-5 contains several thin metal sheets that are hinged together and can be moved by rotating the adjusting ring 1-5. A thin metal sheet forms a ring structure, with a variable diameter through hole 1-4 (similar to an adjustable aperture structure) at the center of the ring structure. An injection hole 1-6 is provided on the edge of the cap 1-3. An injection tube 1-7 for adding nutrient solution into the bottle is inserted into the injection hole 1-6 (the other injection holes 1-6 can be used as wiring channels for the sensor probe 6). Glass wool is laid at the bottom of the bottle body 1-1, and glass stones 1-8 are filled and covered on the glass wool. Plant roots are inserted into the glass stones 1-8. In practical applications, sterilized glass wool and glass stones 1-8 are added to collector 1, cap 1-3 is tightened, plant roots are cleaned (surface soil is thoroughly rinsed), and then rinsed with deionized water. Plant roots are selected and placed into collector 1 through through hole 1-4. The adjusting ring 1-5 is rotated so that the center of several thin metal plates of the ring structure clamps the upper end of the root for positioning and sealing. Collector 1 is adjusted so that the end of the plant root is inserted into glass stone 1-8. Nutrient solution is then injected through injection tube 1-7, and vacuum pump 4 is turned on to clean the plant and the inside of collector 1, filtration bottle 2, etc. in the system. This is repeated 2-3 times. A certain amount of nutrient solution is then injected through injection tube 1-7. Collector 1 with built-in sensor probe 6 is then buried in the soil and allowed to equilibrate for 24 hours. After equilibration, plant root secretions are obtained in collector 1.

[0018] In this embodiment of the invention, the drying bottle 3 is used to prevent the collected liquid from accidentally entering the vacuum pump 4.

[0019] In this embodiment of the invention, the filtration flask 2 is placed in the sample plot and embedded in the soil. After the collector 1 and the filtration flask 2 are cleaned, a certain amount of nutrient solution is still retained in the filtration flask 2. After the collector 1 completes equilibration, the vacuum pump 4 is started to draw the liquid (including root exudates) in the collector 1 into the filtration flask 2. Then, the same amount of nutrient solution is added through the injection tubes 1-7, and the corresponding temperature and humidity are recorded by the temperature and humidity detector 5. The filtration flask 2 has a built-in thermal effect biosensor 7. The root exudates, as an organic carbon source, are specifically recognized and reacted to by the thermal effect biosensor 7, generating a heat change. This temperature change signal can be converted into an electrical signal for acquisition and analysis. This embodiment of the invention provides a preferred thermal effect biosensor 7. Specifically, the thermal effect biosensor 7 includes a support rod, and a thermal effect detection element is fixed at the end of the support rod. The support rod is coated with a heat transfer medium coating, and the end of the support rod and the thermal effect detection element are placed inside the filtration flask 2. In addition to using a thermistor, this invention can also use a thermocouple or a resistance temperature detector (RTD) instead of a thermistor for the thermal effect biosensor 7. The heat transfer medium can be a specially made heat transfer film or coating to transfer temperature changes in the water sample to the thermal effect detection element. In practical applications, specific biomolecules are immobilized on the surface of the thermal effect detection element. Root exudates, as an organic carbon source, are specifically recognized and reacted to, generating heat changes. The real-time temperature change signal output by the thermal effect detection element is converted into an electrical signal for acquisition and subsequent analysis. Biomolecules adhere to the thermal effect detection element, forming an integral part. If the detection of specific exudate components is required, biomolecules that specifically bind to the target exudate, such as enzymes or antibodies, are selected. Biomolecule immobilization on the surface of the thermal effect detection element can be achieved through chemical modification or covalent cross-linking methods, allowing the biomolecules to stably attach to the thermal effect detection element (following specific immobilization steps and methods, and operating according to the characteristics of the biomolecules and the manufacturer's instructions).

[0020] In this embodiment of the invention, the temperature control module 8 is used to maintain the operating temperature of the thermal effect biosensor 7. Preferably, the temperature control module 8 includes a thermostat, a heating circuit or a hot plate, and is equipped with a temperature sensor and a PID controller, etc., to monitor and adjust the temperature of the thermistor. By setting an appropriate operating temperature, adjustments can be made according to specific application requirements and the specifications of the thermistor. A microcontroller or other control circuit is used to monitor the resistance value of the thermistor and take appropriate measures to adjust it as needed. For example, if the resistance value indicates that the temperature is too high, an alarm can be triggered or control measures can be taken to reduce the temperature.

[0021] In this embodiment of the invention, the signal from the thermal effect biosensor 7 is acquired and analyzed by the signal acquisition and processing module 9. The signal acquisition and processing module 9 includes an amplifier, a filter, and an analog-to-digital converter, used to convert the conducted thermal signal into an electrical signal. Appropriate parameters and configurations are set according to the specific acquisition and processing module to ensure accurate recording and analysis of the output signal of the thermal effect biosensor 7. The acquired temperature change data is compared with a pre-calibrated standard curve, and the component content is determined by the curve peaks. Based on the standard curve, the concentration or change of organic acids in the liquid is determined. In this embodiment of the invention, the working principle and process of the signal acquisition and processing module 9 are the same as those of commonly used spectrophotometers.

[0022] In this embodiment of the invention, after the system is assembled, the sensor needs to be validated and optimized. This involves calibration and standardization using solutions of known concentrations to verify the sensitivity and selectivity of the thermal effect biosensor 7, and to make necessary adjustments and optimizations. Specifically, the component to be detected is first selected, as different components have different specific molecules, and then a curve calibration is performed using solutions of standard concentrations.

[0023] Based on this, the present invention provides a method for in-situ monitoring of plant root exudates using the above-mentioned system, the method comprising the following steps: S1. Data Acquisition: Real-time monitoring is performed using a temperature and humidity detector 5 and a thermal effect biosensor 7, and the output signals of the temperature, humidity and biosensor are acquired, which will be used as input data.

[0024] Step S1 more specifically includes the following process: (1) Add the disinfected glass wool and glass stones 1-8 into the collector 1, insert the sensor probe 6 of the external temperature and humidity detector 5, and tighten the cap 1-3. (2) Select the plant roots to be monitored and clean them in situ. Insert the cleaned plant roots into the collector 1 through the through hole 1-4 of the cap 1-3. Adjust the adjusting ring 1-5 to clamp the upper end of the root system for positioning and sealing. Adjust the collector 1 so that the plant roots are inserted into the glass stone 1-8. (3) By inserting an injection tube 1-7 into the cap 1-3 of the collector 1, injecting nutrient solution into the injection tube 1-7, and turning on the vacuum pump 4, the nutrient solution will clean the collector 1 and the filtration bottle 2 in sequence. The purpose of this cleaning operation is that after the plant root exudates are collected, there is no need to carry out the subsequent process of filtration by the pore membrane as soon as possible. The operation steps are simple and fast, and the migration components and total amount of organic matter change little, which can reflect the real-time state of the exudates. (4) Inject nutrient solution through injection tubes 1-7 and bury collector 1 in the soil for 24 hours to balance; (5) After equilibration, the secretion collection liquid in the collector 1 is pumped into the filtration bottle 2 by the vacuum pump 4, and the same amount of nutrient solution is added through the injection tubes 1-7, and the corresponding temperature and humidity are recorded. (6) The heat change of the secretion collection liquid is monitored in the filtration flask 2 by the built-in thermal effect biosensor 7.

[0025] The monitoring data from S2, temperature and humidity detector 5, and thermal effect biosensor 7 are converted, stored, and analyzed by computer. The analysis data from thermal effect biosensor 7 are used to determine the component content through image plotting and curve peak determination.

[0026] Step S2 more specifically includes the following processes: (7) Preprocessing: As needed, perform preprocessing operations such as smoothing, filtering or noise removal on the data to reduce interference in the data.

[0027] (8) Curve peak detection: Analyze the waveform of the output signal of the thermal effect biosensor 7 and use the peak detection algorithm to find the peak point in the curve.

[0028] (9) Peak Analysis: Peak analysis is performed based on the location, amplitude, and shape of the peak point. Parameters such as the area, width, and height of the peak can be calculated to obtain more information.

[0029] (10) Calibration and quantification: Based on the standard curve or calibration coefficient at known concentrations, the peak parameters are correlated with the component content to determine the concentration of the target liquid.

[0030] (11) Visualization: Using the data analysis results, the monitoring data and analysis results are presented graphically by drawing line graphs, bar charts or other visualization methods. This can provide more intuitive information so that users can understand and analyze it.

[0031] In the implementation of this invention, taking the monitoring of ammonia nitrogen content using a thermal effect biosensor 7 as an example, the monitoring time is assumed to be 1 hour, and data is recorded once per minute. The exemplary data shown in Table 1 below can be obtained: Table 1 0 25 7 35 1 26 8 32 2 27 9 30 3 30 10 28 4 32 11 27 5 34 12 26 6 38 13 25 Plot the obtained data as follows: Figure 3As shown in the graph, a peak can be observed. The peak represents the highest point of ammonia nitrogen content. Assume a significant peak is observed at the 6th minute of the data, with the temperature reaching 38 degrees Celsius. Based on previous research and calibration models (calibration models are obtained by measuring the physicochemical properties of a series of known component standard substances to obtain a curve containing the numerical values ​​of those properties; the acquisition of calibration models is an existing technique), it is known that 38°C corresponds to a specific ammonia nitrogen content (e.g., 10 mg / L). Therefore, by analyzing the peak characteristics in the graph and combining them with the previously established calibration model, the ammonia nitrogen content can be determined to be 10 mg / L.

[0032] In the implementation of this invention, the monitoring of organic acid content using a thermal effect biosensor 7 is taken as an example, based on the above implementation process. Table 2 is an example data table, showing the relative changes of organic acid components in the liquid at different time points.

[0033] Table 2 0 0.1 0.3 0.2 10 0.2 0.5 0.4 20 0.3 0.6 0.6 30 0.4 0.7 0.8 40 0.5 0.8 1.0 Table 2 shows that the relative content of organic acid components changed at different time points.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for in-situ monitoring of plant root exudates, characterized in that, The system includes a plant root exudate collector, a filtration flask, a drying flask, and a vacuum pump. Under the continuous negative pressure of the vacuum pump, the liquid from the plant roots in the collector enters the filtration flask through a silicone tube; wherein, The collector has a built-in sensor probe for an external temperature and humidity detector, and the filtration flask has a built-in thermal effect biosensor. The thermal effect biosensor is connected to the temperature control module, and the temperature control module is connected to the signal acquisition and processing module. The signal acquisition and processing module is used to convert the conducted thermal signal into an electrical signal, which is compared with a standard curve. The content of each component in the plant root exudate is determined by the curve peak. The thermal effect biosensor includes a support rod, a thermal effect detection element is fixed at the end of the support rod, and a heat transfer medium coating is applied to the support rod. The end of the support rod and the thermal effect detection element are placed inside a vacuum filtration flask. The thermal effect detection element is one of a thermistor, a thermocouple, and a resistance temperature detector. The collector includes a bottle body with an interface for connecting a silicone tube at the bottom. The top opening of the bottle body is sealed with a cap. The cap has a through hole for adding plant roots into the bottle body, an adjustment ring for adjusting the size of the through hole, and an injection hole on the edge of the cap. An injection tube for adding nutrient solution into the bottle body is inserted into the injection hole. The bottom of the bottle body is lined with glass wool, and glass stones are filled and covered on the glass wool, with plant roots inserted into the glass stones.

2. The system as described in claim 1, characterized in that, The inlet of the filtration flask is equipped with a filter.

3. A method for in-situ monitoring of plant root exudates using the system described in claim 1 or 2, characterized in that, The method includes the following steps: (1) Add the disinfected glass wool and glass stone into the collector, insert the sensor probe of the external temperature and humidity detector, and tighten the cap. (2) Select the plant roots to be monitored and clean them in situ. Insert the cleaned plant roots into the collector through the through hole of the cap and adjust the collector so that the plant roots are inserted into the glass stone. (3) By inserting an injection tube into the cap of the collector, the nutrient solution is injected into the injection tube, and the vacuum pump is turned on. The nutrient solution is used to clean the collector and the filtration flask in sequence. (4) Inject nutrient solution through the injection tube and bury the collector in the soil for 24 hours to allow it to equilibrate. (5) After equilibration, the secretion collection liquid in the collector is pumped into the filtration flask by a vacuum pump, and the same amount of nutrient solution is added through the injection tube. The corresponding temperature and humidity are recorded. (6) The heat change of the secretion collection liquid is monitored in the vacuum filtration flask by a built-in thermal effect biosensor; (7) The monitoring data of temperature and humidity detectors and thermal effect biosensors are converted, stored, analyzed and imaged by computer, and the content of each component in plant root exudates is determined by curve peaks.

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