JP7385880B2 - Plant drought stress diagnosis method - Google Patents

Description

The present invention relates to a technique for diagnosing drought stress (stress due to water shortage, water stress, water stress) in plants. Specifically, the present invention relates to a technique for directly diagnosing the drought stress state of plant roots, rather than indirect evaluation from the above-ground parts of the plant or the growth environment.

Lack of soil moisture during plant cultivation causes a decline in growth and productivity. In particular, water shortage in the rhizosphere causes calcium deficiency, boron deficiency, etc. in the plant, and is a factor that promotes physiological disorders in the plant. It can also cause symptoms of frizz in the above-ground parts and weaken the immune system, leading to the development of diseases.
In the cultivation of agricultural crops, understanding the drought stress state of plant roots is considered to be an important technique for improving productivity and avoiding physiological disorders. It is difficult to diagnose the drought stress condition of the roots.

Therefore, in the prior art in this technical field, a method has been used to "indirectly" estimate the state of the roots by understanding the state of the above-ground part.
The simplest method is to observe the above-ground parts of the plant, such as leaves, to determine whether the plant exhibits symptoms of water shortage. However, the conditions that can be determined by this method are conditions such as curling symptoms caused in the above-ground parts as a result of the roots continuing to receive strong drought stress, and the conditions that can be determined by this method are conditions such as curling symptoms caused in the above-ground parts as a result of continued strong drought stress on the roots, and early stages of drought stress where symptoms have not yet appeared in the above-ground parts. It is not possible to detect the state of the roots in the area.
In addition, methods to understand the water status of plants as numerical values include methods that measure the water potential of above-ground leaves, methods that measure leaf surface temperature using infrared images, and changes in near-infrared reflection spectra. (Patent Document 1, etc.). However, all of these techniques are based on the principle of measuring the condition of the above-ground parts of the plant, such as leaves, and are not technologies that can directly grasp the condition of the roots, which are the ``underground part.'' It is not possible to detect drought stress conditions in roots at an early stage when no effects have occurred. Furthermore, these measurements require a dedicated measuring device to be taken to the cultivation site, and are not recognized as a method that can be widely used at general cultivation sites.

In addition, as a technique different from the above, a method is used to "indirectly" determine the drought stress state of a plant by measuring the amount of water in the soil in the environment in which the plant is cultivated.
However, since the value that can be ascertained by this method is only the soil moisture content in the cultivation environment, it is not recognized as a method that can directly diagnose the drought stress state that plants under cultivation are actually experiencing.

International publication WO2007/129648

The present invention has been made in view of the above-mentioned circumstances of the prior art, and the problem is that indirect evaluation from the above-ground parts of the plant, the growth environment, etc. is not possible with regard to understanding the drought stress state of the plant. The purpose of this study is to provide a technology that directly diagnoses root drought stress.

In the situation of the prior art described above, the present inventors conducted intensive research and found that soybean, an agricultural product, was cultivated in various soil environments with different moisture conditions. We found that the amount of volatile compounds released from the roots increased compared to plants grown in soil with sufficient soil content.
After repeated studies, the present inventors found that in plants grown in dry soil, the amount of volatile compounds released as gases from the roots of alcohols, aldehydes, and ketones increases. . Similarly, we found that in plant roots grown in dry soil, the amount of volatile compounds released as gases from the roots of sesquiterpenes increased.
Furthermore, the inventors have conducted extensive studies and found that the increase or decrease in the amount of gas released from volatile compounds reflects the water conditions in the rhizosphere at that time, even when the cultivation conditions are changed between humidification and drying. It was found that the value changes accurately.
Based on these findings, the present inventors used the amount of volatile compounds released in the form of gases from plant roots as an index value (marker) to detect the early stage when no effects are observed on above-ground parts such as leaves. We have come up with the idea that it will be possible to directly diagnose drought stress in plant roots even in dry conditions.

The present inventors have completed the present invention based on the above findings. The present invention specifically relates to the inventions described below.
[Section 1]
A method for diagnosing drought stress in a plant to be diagnosed, comprising:
(1) A step of using the amount of volatile compounds released as gas from the roots of the plant or a value based on the amount of release as an index value;
A method for diagnosing drought stress in plants, the method comprising:
[Section 2]
After the step described in (1) above,
(2) Comparing the index value of the plant to be diagnosed with the corresponding value of a negative control plant grown in moist soil to determine whether there is a substantial increase or the degree of increase between the index values. ,
The method according to item 1, comprising:
[Section 3]
The volatile compound is
is an alcohol, aldehyde, or ketone having 5 to 8 carbon atoms; is a sesquiterpene; or is one or more compounds selected from the above compounds;
The method according to item 1 or 2.
[Section 4]
The volatile compound is
1-hexanol, (Z)-3-hexen-1-ol, 6-methyl-5-hepten-2-one, 2-octanone, 3-octanone, 1-penten-3-ol, hexanal, or 3-pentanone or one or more compounds selected from the above compounds;
The method according to any one of Items 1 to 3.
[Section 5]
Item 5. The method according to any one of items 1 to 4, wherein the plant to be diagnosed is a plant belonging to the genus Soybean (Glycine).
[Section 6]
A system for detecting drought stress in plants, the system comprising:
The system includes a gas collection section, a dehumidification section, and a volatile compound detection means as constituent members,
(A) The gas collection section is a member including a tubular or container-like structure with an opening structure for taking in gas from the soil, and the volatile compound released from the roots through the opening structure. A member capable of collecting gas containing
(B) The dehumidification section is a member including a tubular or container-like structure connected to the gas collection section so as to be ventilated directly or through another ventilable member, and the dehumidification section A member that can dehumidify water vapor contained in the gas inside the
(C) The volatile compound detection means detects a volatile compound contained in the gas that has passed through the dehumidification section, or a volatile compound that has been adsorbed by a volatile compound adsorbent from the gas that has passed through the dehumidification section. is a device or equipment capable of
A plant drought stress detection system used for carrying out the method according to any one of Items 1 to 5.
[Section 7]
6. The plant drought stress detection system according to item 6,
(A') The gas collection section is a member including a tubular structure having a tip portion into which soil can be inserted and an opening structure for taking in gas;
A plant drought stress detection system used for carrying out the method according to any one of Items 1 to 5.
[Section 8]
The plant drought stress detection system according to item 6 or 7,
The system includes a gas suction means as a component,
(D) the gas suction means is connected to the end of the connected component in a ventilable manner, either directly or through another ventilable member, to enable gas flow in a ventilation channel; is a suction pump that
A plant drought stress detection system used for carrying out the method according to any one of Items 1 to 5.
[Section 9]
The plant drought stress detection system according to any one of items 6 to 8,
The system includes a volatile compound adsorbent as a component,
(E) The volatile compound adsorbent is disposed inside a tubular or container-like structure that is connected to the dehumidifying section so as to allow ventilation, either directly or through another ventilable member. can be,
(C') The volatile compound detection means is a device or equipment that is not connected as a ventilation flow path to the above-mentioned constituent members, and the volatile compound adsorbed by the volatile compound adsorbent is thermally desorbed. is a device or equipment that can be detected by remote control;
A plant drought stress detection system used for carrying out the method according to any one of Items 1 to 5.
[Section 10]
An apparatus for detecting drought stress in plants used for carrying out the method according to any one of Items 1 to 5, comprising:
An apparatus comprising the gas collection section, dehumidification section, and volatile compound detection means according to any one of items 6 to 8 as constituent members,
(C'') The sensor portion of the volatile compound detection means is located inside a tubular or container-like structure that is connected to the dehumidifier directly or through another ventilable member to allow ventilation. A device or device that is arranged in such a way that the sensor part can detect volatile compounds contained in the gas.
Plant drought stress detection device.

The present invention makes it possible to provide a technology for directly diagnosing drought stress in the roots, rather than indirect evaluation from the above-ground parts of the plant or the growth environment. Become.
More specifically, since the present invention is a technology that directly detects volatile compounds released from roots, stress conditions in roots due to lack of soil moisture can be detected in the early stages before the effects appear on above-ground parts such as leaves. It becomes possible to detect in stages. As a result, in the present invention, it is possible to early avoid growth decline and physiological disorders due to lack of soil moisture.
Furthermore, in the present invention, by employing an embodiment in which gas containing volatile compounds generated from the roots of the target plant is directly collected, it is also possible to diagnose the plant body non-destructively.

FIG. 2 is a photographic image of the appearance of the above-ground part of a plant after each treatment in a cultivation test in which each treatment according to Example 1 was performed.

FIG. 3 is a diagram showing measured values of the amount of volatile compounds detected in GC/MS analysis according to Example 1.

FIG. 3 is a diagram showing measured values of the amount of volatile compounds detected in GC/MS analysis according to Example 1.

FIG. 3 is a diagram showing measured values of the amount of volatile compounds detected in GC/MS analysis according to Example 1.

1 is a schematic diagram showing one embodiment of a plant drought stress detection system according to the present invention.

It is a schematic diagram showing another aspect of a dehumidification part (4) regarding a plant drought stress detection system concerning the present invention.

Embodiments of the present invention will be described in detail below. Note that the technical scope of the present invention is not limited to embodiments that include all of the configurations described below. Further, the technical scope of the present invention does not exclude aspects including configurations other than those described below.

1. Method for diagnosing drought stress in plants The present invention is a technology for diagnosing drought stress in plants, which directly evaluates the drought stress that the roots are experiencing, rather than indirectly assessing the above-ground parts of the plant or the growing environment. related to diagnostic techniques.
Specifically, the present invention provides a method for diagnosing drought stress in a plant to be diagnosed, in which the amount of a volatile compound released as a gas from the roots of the plant or a value based on the amount of release is set as an index value. The present invention includes an invention relating to a method for diagnosing drought stress in plants, which is characterized by including the steps of:

[Target for diagnosis]
The method according to the present invention is a method that enables diagnosis of the drought stress state of a plant by evaluating, as an index value, the influence of roots affected by water shortage in the rhizosphere soil with respect to the growth state of the plant.
Here, the term "drought stress" as used herein refers to physiological changes that occur in a growing plant to be diagnosed due to lack of water in the soil of the growing environment. Means the same meaning as the terms water stress, moisture stress, etc.
Furthermore, in this specification, "diagnosis of drought stress" refers to the act of quantifying and evaluating, as an index value, the drought stress experienced by a growing plant to be diagnosed due to lack of moisture in the soil in the growing environment. .

In the method according to the present invention, by detecting volatile compounds generated from the roots of the plant to be diagnosed, it is possible to detect This makes it possible to directly grasp the current state of the situation.
That is, the method according to the present invention makes it possible to directly detect drought stress in the roots of a plant. It also becomes possible to determine the degree of drought stress in the roots of a plant. Furthermore, it is possible to directly diagnose drought stress on plant roots even in early dry conditions where no effects are observed on above-ground parts such as leaves.

The method according to the present invention can be applied to any type of plant that releases volatile compounds as a gas from its roots in response to lack of moisture in the soil in the growing environment. .
The method according to the present invention is, in principle, a method that uses secondary metabolites resulting from activation of lipid metabolism and plant hormones associated with drought stress response as an indicator, so it is a method that can be widely applied to plants in general. It is recognized that For example, plants such as agricultural crops, fruit trees, garden plants, etc. that have such characteristics can be targeted for diagnosis.
Plants to be diagnosed according to the present invention include plants belonging to the leguminous family, considering the commonality of plants that release volatile compounds as gases from their roots and the physiological responses of their roots. can. Legumes have rhizobia in their roots, and are thought to be susceptible to effects such as lipid decomposition in response to drought stress. In particular, application to plants belonging to the genus Soybean and its closely related genera (plants of the French bean family) can be mentioned preferably. Here, soybean plants and their related genera include Glycine, Vigna, Phaseolus, Butea, Cajanus, Canavalia, Erythrina, Hardenbergia, Lablab, Mucuna, Pachyrhizus, Psophocarpus, Pueraria, Rhynchosia, etc. I can list many.

As plants to be diagnosed according to the present invention, plants belonging to the soybean genus (Glycine) are particularly preferably applied from the viewpoint of commonality in physiological mechanisms related to root responses to drought stress. Plants belonging to the soybean genus (Glycine) have a high water requirement in their roots, so it is recognized that their physiological response to water shortage in the roots is sensitive, which may be difficult to detect in plants of other classifications. However, the detection sensitivity for the soybean genus is recognized to be good.
That is, as a plant to be diagnosed according to the present invention, it is preferable to use a plant belonging to the soybean genus (Glycine) as a diagnostic target.
Here, examples of plants belonging to the genus Soybean include plants of plant species classified under the genus Soybean. In addition, plants, varieties, and lines derived from plants belonging to the genus Soybean (plants, varieties, and lines created through cross-breeding, mutation, artificial genetic manipulation, etc. using plants belonging to the genus Soybean), which are mentioned above. Things with characteristics can also be targeted for diagnosis.
Furthermore, in the method according to the present invention, it is particularly preferable to use plants belonging to soybean (Glycine max) as the diagnostic target from the viewpoint of commonality in the physiological mechanisms of stress responses related to the above-mentioned characteristics. Here, examples of plants belonging to soybean include plants classified as Glycine max and plants of varieties and lines belonging to this species. Furthermore, plants, varieties, and lines derived from plants belonging to Glycine max and having the above-mentioned characteristics can also be targeted for diagnosis.
Examples of the plants (individuals) include plants (individuals) produced by hybridization, mutation, artificial genetic manipulation, etc. using plants belonging to Glycine max.
In addition, such cultivars and lines include, for example, cultivars and lines that collectively have the characteristics of plants created by crossbreeding, mutation, artificial genetic manipulation, etc. using plants belonging to Glycine max. .

The plant to be diagnosed according to the present invention is preferably a plant that has been grown for a certain period of time in the environmental soil where it is grown or cultivated. That is, it is desirable to target plants whose roots are capable of physiological responses in accordance with the moisture in the soil. For example, it is desirable that at least 7 days or more, preferably 14 days or more have passed since transplantation, etc., and the plant is recognized to be adapted to the environmental soil and growing.

[analysis]
The method according to the present invention includes the step of collecting a gas containing a volatile compound released as a gas from the roots of a plant to be diagnosed. Furthermore, the method according to the present invention includes the step of detecting volatile compounds from the collected gas.

In the method according to the present invention, an example of a method for collecting volatile compounds released as a gas from roots is to collect the roots of a plant to be diagnosed, and collect volatile compounds released as a gas from the roots. Examples include methods for collecting chemical compounds. Although it is possible to collect the entire root of the plant, it is preferable to collect a portion of the root so as to have less influence on the growth of the plant.
In the method according to the present invention, although it is possible to use roots for analysis as long as they have been harvested for several hours, it is preferable to use roots immediately after harvesting from plants in a growing state for analysis.
The analysis of volatile compounds contained in the gas from the collected roots can be carried out using ordinary gas component analysis techniques. As an example of an embodiment (the embodiment shown in Example 1), the collected roots and an adsorbent capable of adsorbing volatile compounds are placed in a sealed container or sealed bag-like body (glass container, hard resin container, soft resin container, etc.). An example of this method is to place the compound in a plastic bag (resin bag, film bag, etc.) and collect volatile compounds generated as a gas in the internal space of the container.
Note that gas collection in this embodiment is preferably performed using a method that ensures quantitative comparison between samples. For example, when collecting gas from each sample, it is possible to carry out the collection process under similar conditions such as the amount of roots to be collected, the sampling site, the collection conditions (temperature, time, etc.), and the amount of gas to be collected. desirable.

In addition, as another embodiment of gas collection from the roots (the embodiment shown in Example 3), a tubular member capable of capturing gas generated from the roots is placed near the roots in the soil of a growing plant. For example, a method can be mentioned in which a gas containing a volatile compound is directly collected through the member. In this embodiment, since the method does not require collection of plant roots, it is possible to non-destructively diagnose the growing plant to be diagnosed. A specific embodiment for realizing this aspect is described in paragraph 2 below. This can be carried out using a system or device using the gas collection container or gas collection tube described in .
Note that gas collection in this embodiment is preferably performed using a method that ensures quantitative comparison between samples. For example, it is desirable to carry out the collection process under similar conditions for gas suction from the soil (flow rate, time, etc.), gas sampling site (distance from roots, depth), etc.

Detection of volatile compounds in the method of the present invention can be performed by subjecting the gases collected as described above to analysis using a direct or indirect method. Here, volatile compounds contained in the collected gas can be detected using a normal method used in gas component analysis.
For example, i) it is possible to directly detect and analyze volatile compounds contained in gas using a device or device sensor that can analyze volatile compounds contained in gas (sensors, etc.). direct detection method using In another embodiment, ii) after the volatile compounds contained in the collected gas are adsorbed on an adsorbent, the volatile compounds are recovered as a gas in a head space etc. by thermal desorption from the adsorbent, and then It is possible to analyze volatile compounds from (method using adsorbent).
Here, the detection of volatile compounds and the measurement of their amount can be carried out using any method as long as it is possible to measure the amount of volatile compounds with a sensitivity that can detect the difference between the plant to be diagnosed and the negative control. It is also possible to adopt
For example, paragraph 2 below. This can be carried out using the various devices and equipment described as volatile compound detection means described in . Regarding adsorbents capable of adsorbing volatile compounds, see paragraph 2 below. This can be carried out using the volatile compound adsorbent described in .

[Indicator value]
The diagnostic method according to the present invention is a method including the step of using as an index value the amount of volatile compounds released from the roots of a plant to be diagnosed or a value based on the amount of volatile compounds released.
The "volatile compound release amount" which serves as an index value in the present invention can be determined as a value representing the amount of volatile compounds contained in the gas released from the roots. Here, the release amount does not need to be the total amount of volatile compounds generated from the roots, but it should be measured under certain conditions that can be compared between samples, and the obtained measurement values can be compared between samples. It can be determined as a released amount (quantitative value).
For example, it is possible to determine the amount of volatile compounds released from the measured values of volatile compounds detected from the above-mentioned gas or adsorbent collected under certain conditions.

In addition, "a value based on the amount of volatile compound released" is a value calculated from the above-mentioned amount of released volatile compound, and the amount of released amount can be used as an index value that can be compared between multiple samples. refers to a value. For example, a gas containing volatile compounds emitted from roots is collected under certain conditions, the amount of volatile compounds contained in the collected gas is measured, and the measured value is taken as the value (quantitative value). It is also possible.
Here, the value based on the release amount includes, in addition to the measured absolute value, a value expressed as a relative value that allows comparison of the release amount between samples. It also includes values calculated by multiplying by coefficients and values calculated by adding and subtracting constants.
Furthermore, the value based on the amount of released volatile compounds may be a value based on the amount of released two or more volatile compounds. Examples of the value based on the amount of two or more volatile compounds released include the total amount of the two or more volatile compounds whose amount released from the roots increases due to the influence of drought stress. Further, the total amount of these volatile compounds can also be mentioned.

The index value according to the present invention or its basic value, ``amount of volatile compound released'', is defined as a soil environment containing sufficient moisture when a plant grows in a soil environment lacking moisture (dry soil). This refers to the amount of volatile compounds emitted that is detected as a substantial increase in the amount of volatile compounds that are detected compared to when grown in (irrigated soil).
The fluctuation behavior of the release amount of the volatile compound is a quantitative change that reflects the fluctuation of secondary metabolites caused by the activation of lipid metabolism and plant hormones due to the influence of dry soil on plant roots (response to drought stress). This is the result. Therefore, it is recognized that the degree of variation in the amount of volatile compounds released is a quantitative result that reflects the endogenous compositional variation of metabolic reactions in the "roots" of plants due to stress responses to drought. That is, it is estimated that the degree of fluctuation behavior in the amount of volatile compound released is a degree that correlates with the degree of drought stress in the roots of the plant to be diagnosed.
Therefore, the degree of fluctuation behavior in the release amount tends to be such that the greater the influence from drying of the soil, the greater the increase in fluctuation in release amount compared to the negative control of plants grown in soil containing sufficient moisture. It is recognized that there is.
The fluctuation behavior of the release amount of the volatile compound is a value that accurately changes to reflect the influence of the water content in the soil and the water conditions of the rhizosphere at that time, as shown below. This is shown as an experimental result in Example. For example, when the cultivation conditions are such that the soil is alternately moistened and dried, the amount of volatile compounds released is detected as a value that reflects the stress state being received from the moisture condition of the rhizosphere at that time.

[Volatile compounds]
The diagnostic method according to the present invention utilizes the phenomenon that the amount of volatile compounds released from the roots of plants grown in dry soil is increased compared to plants grown in soil containing sufficient moisture. . That is, in the diagnostic method according to the present invention, by detecting an increase in volatile compounds generated from the plant roots, it is possible to detect the drought stress that the plant roots are receiving from the soil.

In the diagnostic method according to the present invention, a volatile compound whose amount is released as a gas from the root surface as a physiological response to water shortage in the rhizosphere of the plant to be diagnosed is used as an indicator compound.
Examples of the volatile compound include lipid decomposition products that are decomposed by promoting the production of lipid peroxide due to a dry stress response. Specifically, it is preferable to use a compound that belongs to alcohols, aldehydes, or ketones and whose amount is released as a gas from the root surface in response to a lack of water in the rhizosphere as an indicator compound. It is. More specifically, in the diagnostic method according to the present invention, a compound belonging to alcohols, aldehydes, or ketones having a carbon number of C4 to C12, or one or more compounds selected from the above compounds is used as an indicator compound. becomes possible. More specifically, in the diagnostic method according to the present invention, a compound belonging to alcohols, aldehydes, or ketones having a carbon number of C5 to C8, or one or more compounds selected from the above compounds is used as an indicator compound. becomes possible.
More specifically, in the diagnostic method according to the present invention, 1-hexanol, (Z)-3-hexen-1-ol, 6-methyl-5-hepten-2-one, 2-octanone, 3-octanone, 1- It is preferable to use penten-3-ol, hexanal, 3-pentanone, or one or more compounds selected from the above compounds as the indicator compound.

Further, examples of the volatile compounds include secondary metabolites resulting from activation of plant hormones and the like due to drought stress response. More specifically, it is possible to utilize as an indicator compound a compound belonging to the sesquiterpenes group whose amount released as a gas from the root surface increases in response to water shortage in the rhizosphere.
That is, in the diagnostic method according to the present invention, a compound belonging to sesquiterpenes or one or more compounds selected from the above compounds can be used as an indicator compound.

In the diagnostic method according to the present invention, detection is performed by selecting a volatile compound whose generation amount increases significantly in response to dry rhizosphere soil conditions compared to when the rhizosphere soil is humidified, and using this compound as an indicator compound. This is preferable in terms of sensitivity. That is, in the present invention, 1-hexanol, (Z)-3-hexen-1-ol, 6-methyl-5-hepten-2-one, or one or more compounds selected from the above compounds is used as an indicator compound. It is more suitable to use These compounds show a large degree of increase in release in response to drought stress, making it easier to detect differences relative to negative control plants.

In the diagnostic method according to the present invention, compounds that are similar to these volatile compounds and exhibit similar fluctuation behavior can also be used as indicator compounds. Examples of similar compounds include compounds that have the same basic skeleton as the above-mentioned volatile compounds, but have undergone modifications that do not significantly change the basic skeleton, such as introduction of functional groups, oxidation, reduction, and substitution of atoms. be able to.
In the diagnostic method according to the present invention, the above-mentioned volatile compounds and their analogous compounds include compounds in their ionized states and in various equilibrium reaction states.

Furthermore, in the diagnostic method according to the present invention, two or more volatile compounds whose generation amount from roots increases due to the effects of drought stress described above may be selected, and an index value may be calculated based on these values. It is possible.

[Detection of differences from negative control plants]
In the diagnosis according to the present invention, regarding the index values measured or calculated above, (a) the index values from the plant to be diagnosed and (b) the index values from the plants grown in moist soil are compared, This is a step of determining whether there is a substantial difference between index values or the degree of the difference.
That is, in the diagnostic method according to the present invention, after the step of creating an index value as described above, the index value in the plant to be diagnosed is compared with the corresponding value in a plant grown in moist soil as a negative control, The method includes the step of determining whether there is a substantial increase between index values or the degree of increase.

Here, the term "negative control plant" as used herein refers to a plant for obtaining information on corresponding values for comparison with index values from plants to be diagnosed, and is a plant whose rhizosphere soil is a moisturizing soil containing an appropriate amount of water. This refers to plants that are grown in a dry environment and are not exposed to drought stress.
Here, the moisture content of the "moisturizing soil" that does not give drought stress to plants can be appropriately set depending on the type of plant to be diagnosed. For example, it is desirable to set the rhizosphere pF value to 1.5 to 2.3, preferably 1.7 to 2.0.

Preferably, the diagnostic method according to the present invention is carried out in a manner that allows accurate detection of only changes in the amount of volatile compounds released due to the influence of drying stress. Therefore, when comparing the index value from the plant being diagnosed and the corresponding value from the control plant, changes in volatile compounds originating from other factors other than the relevant influence are reduced as much as possible, and changes other than the relevant influence are determined. It is desirable that the metabolites, etc. of the sample be uniform or substantially uniform between the samples being compared.

As the negative control plants used in the diagnostic method according to the present invention, it is desirable to use plants with the same or substantially the same genetic background. Therefore, it is desirable to use a plant belonging to the same species as the plant to be diagnosed as the negative control plant. In particular, it is preferable to use plants belonging to the same variety line as the plant to be diagnosed.
Furthermore, when a plant species whose genetic background is significantly different from that of the diagnostic target is used as a negative control plant according to the present invention, noise tends to increase and it becomes difficult to make accurate comparisons. However, even if the negative control plant has a genetic background that is somewhat different from the plant to be diagnosed, values from closely related species or plants of the same species but different cultivar lines that are recognized to exhibit substantially the same metabolic fluctuation behavior. If so, it may be possible to make a comparative judgment between the two. In this regard, the diagnostic method according to the present invention does not exclude a mode in which a plant of a type or variety line different from that of the diagnosis target is employed as a negative control plant to detect differences.

In the diagnostic method according to the present invention, the corresponding value obtained from the negative control plant does not exclude the use of information from plants from different growth environments, but in consideration of improving the determination and diagnostic accuracy, It is preferable that the information is from a plant grown in the same growth environment as the plant to be diagnosed except for the growth environment and moisture conditions. Furthermore, the diagnostic method according to the present invention allows an embodiment in which information from plants grown in substantially the same growth environment except for moisture conditions is used as information from negative control plants. Here, "substantially the same growth environment" does not necessarily mean that samples were collected at the same time and date, considering the accuracy of detecting differences that is actually required in actual cultivation sites, etc.; for example, Examples of growing environments include similar weather conditions such as temperature and light, and similar cultivation environments such as soil composition.
Furthermore, although the diagnostic method according to the present invention does not exclude the use of information from plants at different growth stages, it is possible to use values measured or calculated from plants that are recognized to be at the same growth stage as the plant to be diagnosed. is suitable.
Furthermore, the diagnostic method according to the present invention allows an embodiment in which information from a plant recognized to be at substantially the same growth stage as the plant to be diagnosed is used as information from a negative control plant. Here, "substantially the same growth stage" does not necessarily mean that samples were collected at the same date and time, considering the detection accuracy of differences that is actually required in actual cultivation sites, etc.; This also includes the manner in which the sample is collected on date and time.

In the diagnostic method according to the present invention, it is also possible to set a reference value in advance for determining the state of drought stress, and compare it with the reference value to determine the state of drought stress. In this embodiment, by simply subjecting a sample from a plant to be diagnosed to analysis, it is possible to detect an increased difference and determine the stress level by comparing it with corresponding data that can be compared with that plant.
As the value serving as the criterion in this embodiment, it is possible to use information on the amount of volatile compounds released that has been previously obtained from plants grown in an environment where the rhizosphere is in moist soil. That is, in the present invention, it is possible to set a value that should be shown in a non-stressed state based on a value previously measured from a negative control plant in an environment where the rhizosphere is moisturizing soil. In this embodiment, it is possible to employ a predetermined criterion value as the "corresponding value in the negative control plant."
In addition, as standard values in this aspect, by accumulating data information of control plants in the field etc. and creating a database or judgment table for comparison with the plants to be diagnosed, It becomes possible to more easily diagnose drought stress, etc., without cultivating both at the same time.

In the diagnostic method according to the present invention, when detecting a substantial difference, the presence or absence of a difference between the index value from the plant to be diagnosed and the corresponding value from the control plant is used to detect the substantial difference between the index values. It is preferable to determine the presence or absence of a physical difference. Here, the method of diagnosing the stress state by detecting the difference between index values can be carried out in a manner that includes comparison with values from negative control plants. In this embodiment, i) the indicator value in the plant to be diagnosed is compared with the corresponding value in a negative control non-stressed plant, and ii) a substantial difference is detected between these values. If so, it can be determined that the plant to be diagnosed is in a drought stress state. Furthermore, if no substantial difference is detected between them, it can be determined that the plant to be diagnosed is not in a drought stress state.
In addition, the degree of difference between the index values detected here is a value that correlates with the degree of drought stress in the plant, so the larger the degree of difference, the more severe the drought stress state in the plant to be diagnosed. It is possible to determine. Furthermore, the smaller the degree of difference, the milder the drought stress state can be determined.

Furthermore, in the diagnostic method according to the present invention, when a value based on the amount of one type of volatile compound is used as an index value, or when a sum of the amounts of two or more types of volatile compounds is used as one index value, By performing statistical analysis using univariate analysis, it is possible to improve diagnostic accuracy. Here, standard methods can be used for statistical analysis, such as standard error, standard deviation, t-test, ^X2 test, ANOVA test, Mann-Wihtney U test, likelihood ratio test, Wald test, etc. can be mentioned.
In addition, the diagnostic method according to the present invention focuses on two or more types of volatile compounds, calculates two or more index values based on the amount of each volatile compound, and performs multivariate analysis, thereby improving the accuracy of determination. It is also possible to improve Here, multivariate analysis can be performed using a known method. Examples of multivariate analysis include multiple regression analysis, discriminant analysis, logistic regression analysis, quantification class I analysis, quantification class II analysis, principal component analysis, factor analysis, cluster analysis, correspondence analysis, quantification class III analysis, Examples include multidimensional scaling, decision tree analysis, and neural network analysis.
In addition, in the multivariate analysis, the values of plants grown in moist soil (plants not subjected to drought stress), which served as a negative control, and those of plants grown in dry soil (plants subjected to drought stress), which served as a positive control, were calculated. By adding the corresponding values from plants that are present in the plant, it becomes possible to perform even more accurate judgment and diagnosis. For example, when cluster analysis or the like is performed, it is possible to obtain the determination result as a hierarchical clustering tree, which is preferable since it is possible to determine the presence or absence and degree of drought stress with higher accuracy.

2. Plant drought stress detection system and device In the present invention, the above-mentioned paragraph 1. This includes inventions related to systems used to perform drought stress diagnosis using the principles described in . That is, the present invention includes an invention relating to a plant drought stress detection system used for carrying out the above-described method for diagnosing drought stress in plants.

The plant drought stress detection system (1) according to the present invention includes a member for performing a step of directly collecting gas containing volatile compounds released from roots from soil, and a member for performing a step of directly collecting gas containing volatile compounds released from roots, The components include a member for reducing water vapor molecules contained in the gas, and a detection means for detecting volatile compounds contained in the gas.
That is, the plant drought stress detection system (1) according to the present invention is an invention related to a system comprising a gas collection section (2), a dehumidification section (4), and a volatile compound detection means (5) as constituent members. It is. By using the system (1) according to the present invention, it becomes possible to non-destructively diagnose drought stress in plants without damaging the plants growing at the cultivation site.

[Gas collection section]
The system (1) according to the present invention includes, as a component, a gas collection unit (2) for performing a step of directly collecting gas containing volatile compounds released from roots in the soil.
The gas collection unit (2) according to the present invention is a member that includes a tubular or container-shaped structure (22) with an opening structure (23) for taking in gas from the soil. Thereby, the gas collection section (2) functions as a member capable of collecting gas containing volatile compounds released from the roots through the opening structure (23).
Here, in the description of the gas collection part (2) in this specification, the tip part (21) side in the direction of soil insertion is taken as the lower side, and the tubular structure (22) side of the main body is taken as the upper side. Although each shape, etc. is explained using the description in the vertical direction, it is not intended that the actual usage mode is limited only to these directions.

(tubular or container-like structure, tip)
Specifically, it is preferable that the gas collection unit (2) according to the present invention is a gas collection pipe or a gas collection container (2) that includes a tubular or container-like structure in its member structure. .
The gas collection pipe or gas collection container (2) is a member including a tubular or container-like structure (22) with a tip (21) into which soil can be inserted and an opening structure (23) for taking in gas. It is preferable that In this aspect, when the gas collection pipe or gas collection container (2) is inserted into the soil from the tip (21), the gas containing volatile compounds released from the roots through the opening structure (23). is taken into the internal space of the tubular or container-like structure (22), allowing it to function as a component capable of collecting gas from the soil.

The gas collection section (2) includes a tubular or container-like structure (22) that is hollow inside. The tubular or container-like structure (22) is provided with an opening structure (23) in its wall for taking in gas from the soil.
Among the parts constituting the gas collecting section (2), the tubular or container-like structure (22) directs the gas taken in from the opening structure (23) upwardly (downstream direction of gas flow) into its internal space. refers to a tubular or container-like structural part through which gas can pass. Examples of the structure of the tubular or container-like structure (22) include a hollow structure that has a wall surface and allows ventilation inside.
The tubular or container-like structure (22) preferably has an elongated tubular shape including the tip end so that it has a shape suitable for drilling into soil. In addition, in order to prevent gas from entering from the ground, a certain distance is provided between the opening structure (23) and the upper end of the tubular or container-like structure (22), so that the gas taken in from the opening structure (23) Preferably, the shape includes a tubular shape that allows air to flow through the inside.
That is, it is preferable that the gas collection section (2) has a shape in which at least a portion thereof includes the tubular structure (22). Moreover, as for the shape of the gas collection part (2), it is preferable that the entire shape is a tubular structure (22).

The tubular or container-like structure (22) has a cross section in the vertical direction (longitudinal direction) that is circular, elliptical, elliptical, polygonal (triangular, square, more angular, etc.), or rounded. Examples include shapes such as a substantially polygonal shape with a hollow cross section. In particular, a hollow shape with a circular cross section is preferable.
Regarding the portion where the tubular or container-shaped structure (22) becomes a tubular structure, it is preferable that the cross section thereof is in the shape of a circular tubular structure.
The part of the tubular or container-like structure (22) that becomes the tubular structure may have a shape that includes a bent pipe or bent structure in a part thereof, but it is a structure that includes a straight pipe shape in at least a part of it. is suitable. Further, as the tubular or container-like structure (22), a structure whose entire shape is a straight tube is suitable.
Further, as the tubular or container-like structure (22), it is also possible to adopt a structure formed with valves, partitions, etc., or a structure filled with a filter, etc., as long as ventilation inside is ensured. be.

The tubular or container-like structure (22) has a vertical (longitudinal) direction that allows the opening structure (23) to be inserted to a position suitable for collecting gas in the soil generated from the roots when inserting the soil. It is preferable to have a length of .
For example, the total length in the vertical direction of the gas collection part (2) from the lower end of the tip part (21) to the upper end of the tubular or container-like structure (22) (pipe length in the case of a tubular structure) is 5 cm or more, preferably Examples include shapes of 10 cm or more. The upper limit of the total length is 50 cm or less, preferably 30 cm or less, considering operability and gas collection efficiency.
The horizontal width of the tubular or container-like structure (22) (pipe width in the case of a tubular structure) is not particularly limited as long as the pipe width or container width is suitable for internal ventilation; Considering the scale, it is desirable to have a tubular structure whose cross-sectional area is not too large. An example is a structure in which the maximum width of the inner walls in cross section (inner diameter in the case of a circular tube) is 40 mm or less, preferably 20 mm or less. Further, the lower limit of the maximum width between the inner walls (the inner diameter in the case of a circular pipe) is 5 mm or more, preferably 10 mm or more, considering the gas recovery efficiency.
The maximum width between the outer walls (outer diameter in the case of a circular pipe) can be determined according to the maximum width between the inner walls and the thickness of the walls. For example, a shape may be mentioned in which the maximum width between the outer walls (outer diameter in the case of a circular pipe) is about 0.2 to 5 mm larger than the maximum width between the inner walls, but there is no particular limitation.
Further, the width of the tubular or container-like structure (22) in the horizontal direction (tube width in the case of a tubular structure) may be different depending on its vertical portion. For example, the width of the tube or container in the lower part where the opening structure (23) is located is widened, and the width of the tube or container in the upper part is narrowed in order to arrange a filter or the like above the tubular structure (22). It is also possible to do so.

The member constituting the tubular or container-like structure (22) is preferably made of a material whose wall structure (particularly the inner wall) has low gas permeability and whose surface does not easily adsorb organic substances. Further, it is preferable that the material is unlikely to generate volatile compounds derived from the material. Further, the material of the tubular or container-like structure (22) is preferably a material that has sufficient physical strength for insertion into soil, etc. from the viewpoint of functioning as a support for the pipe or container. Examples of the material include hard materials such as hard resin, ceramic, metal, and glass.
More specifically, as the material constituting the tubular or container-like structure (22), materials such as polypropylene resin, fluorocarbon resin, polyimide resin, polycarbonate resin, polymethylpentene resin, acrylic resin, etc. are preferably used. Can be used.
From the viewpoint of gas impermeability and physical strength, it is most preferable to use polypropylene resin or fluorocarbon resin as the material constituting the tubular or container-like structure (22). It is. Examples of fluorocarbon resins include polytetrafluoroethylene (PTFE), fluororubber (FKM), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer. Preferred examples include (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), and the like.

The tip (21), which is the lower end of the gas collection container or gas collection pipe (2), preferably has a tip shape suitable for insertion into soil.
It is preferable that the tip (21) adopts a shape and structure that provides little resistance when a downward force is applied to the tip toward the soil and is suitable for insertion and drilling of the member. .
For example, the shape of the tip (21) may preferably include a cone shape, a pyramid shape, a rod shape, a drill shape, a needle shape, etc. with the apex of the tip portion as the lower end. It is also possible to adopt a configuration in which the lower end is flat and the tip portion has a shape that tapers upward (truncated conical shape, truncated pyramid shape, etc.). Further, these shapes having a rounded lower end (approximately conical shape, approximately pyramidal shape, etc.) are also included.
In addition, if the gas collection container or gas collection tube (2) has an elongated shape with a narrow pipe width, even if the tip, which is the lower end, is flat, it can be used as the tip (21) as it is. It is.

The tip (21) of the gas collection container or gas collection tube (2) can be formed by integrally molding the tip (21) and the tubular or container-like structure (22) in advance. In this case, the material constituting the tip portion (21) can be the same as the material constituting the tubular or container-like structure (22) described above.
In addition, in order to give the tip part (21) a function more suitable for soil insertion, a tubular or container-shaped structure (22) is separately produced and then connected to the lower part of the tubular or container-shaped structure (22). It is also possible to form it by As the tip portion (21) in this embodiment, it is preferable to use a material having sufficient physical strength for insertion into soil, etc. For example, a hard material suitable for soil insertion such as metal, hard resin, or ceramic can be used.

(Opening structure)
The gas collection section (2) includes an opening structure (23) in the wall of a tubular or container-like structure (22) for taking in gas from the soil.
The opening structure (23) is not particularly limited as long as the walls are connected so that gas can be taken in from the soil into the pipe, but as an example, a pipe wall of a tubular or container-like structure (22) is used. Examples include a hole structure formed by opening an opening in the tube, a hole structure formed by drilling a tube wall, and the like. Further, when producing the tubular or container-like structure (22), it is also possible to form the open structure (23) by molding the tube wall in advance so as to have an open structure during molding.
It is also possible to embed another tubular member, a ring-shaped member, a mesh member, etc. in the tube wall of the tubular or container-shaped structure (22), and make the opening part the open structure (23).

The opening structure (23) is preferably formed on the side wall of the tubular or container-like structure (22) so that soil, solid matter, etc. cannot easily enter the pipe. That is, the position of the opening structure (23) in the tubular or container-like structure (22) is such that when the tubular or container-like structure (22) is vertically inserted into the soil, the opening structure (23) is positioned perpendicularly to the insertion direction. Preferably, it is formed on a wall.
In addition, the opening structure (23) is formed in a tubular or container-like structure (22) so as to prevent gas from entering from the ground and to adjust the depth of the opening structure (23) during insertion into the soil. It is preferable that it be formed at a certain distance from the upper end. For example, it is desirable to form the opening structure (23) at a position downwardly away from the upper end of the tubular or container-like structure (22) by 3 cm or more, preferably 5 cm or more, more preferably 7 cm or more.
Furthermore, it is desirable that the opening structure (23) is formed near the tip (21). For example, it is desirable to form the opening structure (23) so as to be located within 4 cm, preferably within 2 cm, in the upward direction from the boundary between the tip (21) and the tubular or container-like structure (22).

As for the shape of the opening structure (23), in order to prevent soil and solid matter from being taken into the pipe, it is preferable to have a shape that does not have larger pores than necessary, and it is preferable that the opening structure has a fine pore structure. be. There are no particular restrictions on the shape of the hole, but examples include circular, elliptical, elliptical, polygonal (triangular, square, more angular, etc.), rounded substantially polygonal, etc. be able to. In particular, a circular pore structure can be mentioned preferably.
As for the size of the opening structure (23), it is preferable that the maximum width of the hole (the diameter if the opening structure is circular) is 10 mm or less, preferably 6 mm or less. Optimally, the maximum width of the hole is preferably 5 mm or less. The lower limit is not particularly limited, but may be, for example, 0.1 mm or more.
As a mode of arrangement of the opening structure (23), a mode in which a plurality of fine hole structures are formed and arranged is suitable. The number of holes to be arranged can be determined at any time, but in an embodiment, it is preferably 2 or more, preferably 3 or more.
The opening structure (23) is designed so that the total area of the pores of the opening structure is 50 mm ² or more, preferably 70 mm ² or more, and more preferably 200 mm ² or more, considering the efficiency of gas intake from the soil. , it is preferable to provide an opening structure. Although there is no particular upper limit, it is preferable to arrange the opening structure so that the total area of the hole portion is 500 mm ² or less, for example.

Regarding the arrangement position of the opening structure (23), it is also possible to arrange the opening structure so that it is unevenly distributed in one direction of the wall, and the opening structure can be arranged evenly so as to correspond to all directions of the pipe or container. Aspects are also possible.
Further, as another aspect of the opening structure (23), for example, an opening structure formed in various patterns such as a net shape, a mesh shape, a slid shape, a lattice shape, a honeycomb shape, etc. can be adopted. Further, it is also possible to adopt an embodiment in which a large opening structure is formed as a whole as a set of a plurality of communicating holes or a set of microscopic communicating holes.
Further, the opening structure (23) may have a configuration in which a filter or the like with air permeability is provided in the hole portion in order to prevent soil and solid matter from being taken into the pipe.

(Other structures)
Above the opening structure (23) of the tubular or container-like structure (22) (downstream side of the gas flow), there is a structure for connecting to the next downstream component constituting the system (1) according to the present invention. A connecting portion (24) is provided.
The connection part (24) can be formed at any position on the pipe wall of the tubular or container-like structure (22) as long as it is above the open structure (23) (downstream side of the gas flow). be. For example, it is possible to provide an opening in either the tube wall of the tubular or container-like structure (22), which opening serves as the connection (24).
The connecting portion (24) is preferably located at the upper end (the most downstream side of the gas flow) of the tubular or container-like structure (22). For example, when the upper end of the hollow structure of the tubular or container-like structure (22) (the most downstream end of the gas flow) is an open structure, the opening can be used as it is as the connection part (24).
In addition, as the connection part (24), when the tubular or container-like structure (22) has an upper end wall (the most distal wall), an opening is provided in the end wall and the opening is used as the connection part. (24) is possible.

The connecting portion (24) may have a structure suitable for connection with the next component on the downstream side that constitutes the system (1) according to the present invention. For example, it is possible to employ an engagement/locking structure using a luer connector or the like to ensure airtightness, a structure provided with a spiral groove, or the like. It is also possible to connect the connecting portion (24) and the downstream pipe structure by covering the connecting portion with a covering member made of a soft resin such as rubber. In addition, a soft resin member with adhesive properties that can be attached by piercing a needle-like member made of metal or resin is embedded in the opening of the wall of the tubular or container-like structure (22), and the soft resin member is An embodiment in which the portion is a connecting portion (24) is also possible.

In the gas collection pipe or gas collection container (2), the middle or upper part of the outer wall of the tubular or container-like structure (22) can be used as a gripping part when inserting soil. Moreover, it is also possible to have a structure in which a gripping part such as a grip or a handle is provided on the upper outer wall of the tubular or container-like structure (22).

[Filter section]
The system (1) according to the present invention is configured to include a filter structure downstream of the gas collection section (2) in order to remove particulates, dust, etc. contained in the gas collected from the soil. is suitable.
Although the filter structure may be arranged inside the tubular or container-like structure (22) of the gas collection section, the gas collection section may be arranged as a separate component from the gas collection section (2). It is possible to provide a filter section (3) downstream of (2).
That is, the system (1) according to the present invention includes a filter that is connected to the gas collection section (2) in a ventilated manner directly or through another ventilable member. An embodiment including part (3) as a constituent member is preferable.
The connection position of the filter part (3) is downstream of the gas collection part (2) and upstream of the sensor part (51) of the volatile compound detection means or the volatile compound adsorbent (53). If so, it is possible to connect and arrange it at any arbitrary position. Preferably, in order to prevent the dehumidifying part (4) from becoming contaminated with fine particles from the soil, it is desirable to connect and arrange the dehumidifying part (4) upstream of the dehumidifying part (4).
Furthermore, in the system (1) according to the present invention, an embodiment in which two or more filter sections (3) are provided is also possible. For example, it is also possible to arrange a plurality of filter sections (3) at different arbitrary positions.

The filter part (3) has a container-like or tubular structure (32) equipped with a gas inlet and a gas outlet, and a filter (32) that has air permeability and is capable of removing particulates, dust, etc. 31) etc. can be mentioned. In this structure, the gas introduced from the gas inlet into the container-like or tubular structure (32) of the filter part is physically removed from fine particles and dust during the process of passing through the filter (31), and the gas is discharged. Via the outlet it is possible to supply purified gas to the next component connected downstream of the filter part (3).

The filter part (3) is formed by filling a filter material (31) in a position between a gas inlet and a gas outlet of a container-like or tubular structure (32). Preferably, the filter material (31) is filled and arranged so as to obstruct the flow of air between the gas inlet and the gas outlet of the container-like or tubular structure (32).
As the filter material (31) filled in the filter part (3), it is possible to use a normal filter material. For example, it is possible to use a filter material made of polypropylene, polycarbonate, glass, or the like. The shape of the filter (31) is not particularly limited, but suitable shapes include fibrous, filter, and disc shapes. As one embodiment, it is preferable to use a fiber filter (especially a glass fiber filter) from the viewpoints of physical particle removal, prevention of clogging due to clogging, and less influence on volatile gases. .
One embodiment of the container-like or tubular structure (32) of the filter part (3) is a container-like or tubular structure that is provided with a gas inlet and a gas outlet and whose wall surface is airtight. can. Preferably, a container-like or tubular structure in which the wall structure serves as a physical support for the member can be mentioned. Moreover, a tube-like or film bag-like embodiment can also be mentioned.
Although there are no particular restrictions on the material constituting the container-like or tubular structure (32), it is preferable to use a material that is excellent in gas impermeability, physical strength, and the like. For example, it is possible to employ the same material as the tubular or container-like structure (22) of the gas collection section described above.

[Dehumidification section]
In the system (1) according to the present invention, since many of the volatile compounds to be detected tend to be hydrophobic, the concentration of water vapor contained in the gas collected from the soil may interfere with the detection of volatile compounds. It is desirable to reduce the concentration to a level where no Therefore, from the viewpoint of improving detection sensitivity, it is preferable for the system (1) according to the present invention to include the dehumidifying section (4) as a component.
That is, the system (1) according to the present invention includes a dehumidifying section connected to the downstream side of the gas collection pipe (2) directly or via another component such as a filter section (3). It is preferable to include (4) as a constituent member.

In the system (1) according to the present invention, the dehumidifying section (4) has a container-like or tubular shape that is ventilably connected to the gas collecting section (2) directly or through another ventilable member. It is a member including the structure (42), and is a member capable of dehumidifying water vapor contained in the gas inside the dehumidifying section.
The gas introduced from the gas inlet of the dehumidifying part (4) into the container-like or tubular structure (42) that is the main body of the dehumidifying part (4) passes through the container-like structure or the tubular structure (42). The dehumidified dry gas is supplied to the next component connected downstream of the dehumidifying section (4) through the gas outlet.
In the present invention, it is possible to employ different aspects of the dehumidifying section (4) depending on the means for dehumidifying the water vapor of the gas passing through the interior thereof.

(Embodiment using a pipe wall with a dehumidifying effect)
One embodiment of the dehumidifying section (4) according to the present invention includes a tubular structure (specifically, a tubular structure) (42a) having a gas inlet and a gas outlet; It is possible to adopt an embodiment of the dehumidifying section (4) that allows water vapor to permeate from the inner wall to the outer wall by utilizing the selective water vapor permeation effect of the material of the tube wall in 42a).
In the dehumidifying section (4) of this embodiment, as the gas passes from the gas inlet to the gas outlet in the tubular structure (42a), polymers such as volatile compounds contained in the introduced gas are removed. While water vapor molecules pass through the tube while being retained inside the tube without passing through the walls, water vapor molecules pass through the tube wall and are released to the outside due to the humidity difference with the external environment. Therefore, the water vapor concentration of the gas that has passed through to the outlet of the tubular structure (42a) can be reduced to a concentration that does not interfere with the detection of volatile compounds by GS/MS analysis, sensors, etc.
That is, the water vapor contained in the gas that has come into contact with the inner wall of the tubular structure (42a) is selectively removed to the outside by the action of the tube wall, thereby achieving dehumidification of the water vapor contained in the internal gas.

In this embodiment, the material constituting the tubular structure (42a) of the dehumidification section has a property of allowing water vapor molecules to pass from the inner wall to the outer wall due to the difference in humidity between the inside and outside, without allowing volatile compounds contained in the gas inside the pipe to pass through. It is possible to adopt a material having the following properties. In particular, it is preferable to employ a tube wall made of a non-porous hollow fiber membrane material. More preferably, the tube wall is made of a fluorine-based non-porous hollow fiber membrane material.
Note that the structure of the tube wall may be a composite structure with other materials as long as it does not inhibit the release of water vapor from the outer wall. For example, it is possible to coat the outer wall with a resin material that allows water vapor to pass through, thereby ensuring the physical strength of the tubular structure (42a). Further, in the case of forming a composite structure such as a covering, it is preferable to use a flexible material so that the tubular structure (42a) can be flexibly bent.

In this embodiment, the tubular structure (42a) of the dehumidifying section has a shape that exhibits a dehumidifying effect due to the action of the material of the tube wall, so it is preferable that the tubular structure has a certain length. . For example, a pipe length of 15 cm or more, preferably 30 cm or more is suitable. Further, there is no particular restriction on the upper limit of the pipe length, but it can be, for example, 100 cm or less. The gas inlet and gas outlet of the tubular structure (42a) are preferably formed at both ends of the tubular structure (42a) of the dehumidifying section.

The shape of the tubular structure (42a) is not particularly limited as long as its interior can be ventilated, but the cross section may be circular, elliptical, oval, polygonal (triangular, square, etc. Examples of hollow cross-sectional shapes that can be used as ordinary pipes include the above-mentioned angular shapes, rounded substantially polygonal shapes, and the like. Particularly suitable is a tube structure having a circular cross section.
The tubular structure (42a) is preferably a tubular structure whose cross section has a constant shape. Particularly suitable is a tube structure having a circular tube shape with a constant diameter.
Further, as long as ventilation inside the pipe is ensured, it is also possible to use a pipe structure in which the cross-sectional shape and area of the pipe differs depending on the part, or a pipe structure in which valves, partition walls, etc. are formed.
As for the tube width of the tubular structure (42a), it is desirable that the tubular structure (42a) has a somewhat narrow tubular shape, considering the efficiency of contact with the gas on the inner wall. An example is a tube width structure in which the maximum width between the inner walls of the cross section of the tube (the inner diameter in the case of a circular tube) is 4 mm or less, preferably 2 mm or less. Further, the lower limit of the maximum width between the inner walls (the inner diameter in the case of a circular pipe) is not particularly limited, but in consideration of the ventilation flow rate, it may be, for example, 0.2 mm or more, preferably 0.5 mm or more.

(Aspect using dehumidifier)
As another aspect of the dehumidifying part (4) according to the present invention, the dehumidifying part (4) includes a container-shaped or tubular structure (42b) having a gas inlet and a gas outlet, An example may be an embodiment in which water vapor is adsorbed by a dehumidifier (43) filled in the structure (42b).
The dehumidifying section (4) in this embodiment includes a container-like or tubular structure (42b) equipped with a gas inlet and a gas outlet, and a dehumidifier (43) that has air permeability and is capable of adsorbing moisture. ) can be mentioned. In this aspect, water molecules are physically adsorbed and removed from the gas introduced into the container-like or tubular structure (42b) from the gas inlet during the process of passing through the dehumidifier (43), and the gas passes through the container or pipe. It becomes possible to reduce the water vapor concentration of the gas to a concentration that does not interfere with the detection of volatile compounds by GS/MS analysis, sensors, etc.

In the dehumidifying section (4) of this embodiment, a dehumidifying agent (43) is disposed at any position between the gas inlet and the gas outlet of the container-like or tubular structure. Preferably, the dehumidifier (43) is filled and arranged so as to obstruct the flow of air between the gas inlet and the gas outlet of the container-like or tubular structure (42b).
As the dehumidifier (43) arranged in this manner, it is possible to use a desiccant that is difficult to adsorb polymers and exhibits the property of adsorbing water vapor molecules. One embodiment includes magnesium perchlorate, but is not particularly limited thereto. There are no particular restrictions on the shape of the dehumidifier (43), but from the viewpoint of securing a surface area for efficient adsorption and ensuring ventilation, it may be filter-shaped, filled with particulate carrier, or small ring-shaped. Preferred embodiments include a state filled with a cylindrical carrier, a membrane shape, a disk shape, and the like.

In one embodiment, the container-shaped or tubular structure (42b) constituting the dehumidification section (4) of this embodiment is a container-shaped or tubular structure that is provided with a gas inlet and a gas outlet and whose wall surface is airtight. The following structure can be mentioned. Preferably, a container-like or tubular structure in which the wall structure serves as a physical support for the member can be mentioned. Specifically, a container-like structure having a cylindrical shape or a rectangular tube shape can be mentioned. Further, it is also possible to take the form of a bag-like body such as a tube-like shape or a film bag-like shape.
Although there are no particular limitations on the material constituting the container-like or tubular structure (42b), it is preferable to use a material that is excellent in gas impermeability, physical strength, and the like. For example, it is possible to employ the same material as the tubular or container-like structure (22) of the gas collection section described above.

[Volatile compound detection means]
The system (1) according to the present invention includes as a component a volatile compound detection means (5) for detecting volatile compounds contained in gases collected from soil. That is, in the system (1) according to the present invention, volatile compounds contained in the gas that has passed through the dehumidification section (4) or from the gas that has passed through the dehumidification section (4) are adsorbed onto the volatile compound adsorbent. It includes as a component a device or device (5) capable of detecting volatile compounds.
In the present invention, different embodiments of the volatile compound detection means (5) can be adopted depending on the principle of the detection means.

(Direct detection mode)
One embodiment of the volatile compound detection means (5) in the system (1) according to the present invention is capable of directly detecting volatile compounds contained in the gas discharged from the dehumidification section (4). An embodiment includes a volatile compound detection means (5) for detecting a volatile compound.
In the system (1) according to the present invention in this aspect, in order to detect volatile compounds contained in the gas discharged from the dehumidifying part (4), volatile compounds are detected downstream of the dehumidifying part (4). Directly located and provided with possible devices or equipment (5).
That is, in the system (1) according to the present invention in this aspect, the sensor portion (51) of the volatile compound detection means is vented to the dehumidifying section (4) directly or through another ventilable member. A device or device that is arranged inside a tubular or container-like structure (52) that is connected to the sensor part (51) to detect volatile compounds contained in the gas. The embodiment can include the following.

The volatile compound detection means (5) of this embodiment is, for example, capable of detecting and measuring volatile compounds contained in the gas discharged from the dehumidification section (4) outdoors, such as at a cultivation site. Portable or portable small devices and devices can be employed. More specifically, in consideration of detection sensitivity and measurement accuracy, it is preferable to use a trace gas analyzer using an infrared laser, a trace gas component detector using film-type surface stress, etc. can be mentioned.
In this aspect, it becomes possible to perform the step of detecting volatile compounds in real time at the cultivation site of growing plants.

In the system (1) according to the present invention in this aspect, in order to ensure the detection of volatile compounds contained in the gas supplied from the dehumidification section (4), the sensor section (51) of the volatile compound detection means It is preferable to arrange the container-like or tubular structure (52) in the interior space thereof. In addition, if the detection device itself is small, the entire device or equipment of the volatile compound detection means (5) including the sensor portion (51) is placed inside the container-like or tubular structure (52) as it is. It is also possible to adopt such an embodiment.
The container-like or tubular structure (52) of this embodiment is connected to the downstream side of the dehumidifying section (4) so as to be ventilable directly or via another ventilable member. In this embodiment, it is possible to arrange the sensor part (51) of the volatile compound detection means at any position between the gas inlet and the gas outlet of the container-like or tubular structure (52). . Preferably, the sensor part (51) of the volatile compound detection means is disposed in the path of the air flow between the gas inlet and the gas outlet of the container-like or tubular structure (52).

Examples of the container-like or tubular structure (52) include a container-like or tubular structure that is provided with a gas inlet and a gas outlet and whose wall surface is airtight. Preferably, a container-like or tubular structure in which the wall structure serves as a physical support for the member can be mentioned. Moreover, a tube-like or film bag-like embodiment can also be mentioned.
The material constituting the container-like or tubular structure (52) is not particularly limited, but it is preferably a material with excellent gas impermeability, physical strength, etc. For example, it is possible to employ the same material as the tubular or container-like structure (22) of the gas collection section described above.

(Embodiment using volatile compound adsorbent)
Another aspect of the volatile compound detection means (5) according to the present invention is that after the volatile compounds contained in the gas discharged from the dehumidifying section (4) are adsorbed on the volatile compound adsorbent (53), , an embodiment using a volatile compound detection means (5) that enables detection of volatile compounds adsorbed on the adsorbent (53).
In the system (1) according to the present invention in this aspect, a volatile compound adsorbent is provided on the downstream side of the dehumidifying part (4) in order to detect volatile compounds contained in the gas discharged from the dehumidifying part (4). (53) is placed, and volatile compounds adsorbed on the adsorbent (53) are detected.
That is, in the system (1) according to the present invention in this aspect, the volatile compound detection means (5) is not disposed downstream of the dehumidification part (4), and the gas discharged from the dehumidification part (4) is In order to collect volatile compounds contained in the air, a volatile compound adsorbent (53) may be arranged downstream of the dehumidification section (4).

The volatile compound detection means (5) of this embodiment is a device or equipment that is not connected as a ventilation channel to the above-mentioned constituent members, and detects volatile compounds adsorbed by the volatile compound adsorbent. Any possible device or equipment is used.
As the volatile compound detection means (5) in this embodiment, any method can be adopted as long as it is capable of detecting volatile compounds from the gas recovered from the volatile compound adsorbent (53). For example, various techniques using gas chromatography or mass spectrometry can be employed. Considering detection sensitivity and measurement accuracy, it is preferable to use a mass spectrometer such as GC/MS.
In this embodiment, in order to perform a step of adsorbing volatile compounds to be analyzed by the volatile compound adsorbent (53) from the roots of the growing plants at the cultivation site, the equipment and devices used as the volatile compound detection means (5) are used. There is no need to take equipment etc. to the cultivation site or outdoors. That is, in this embodiment, there is no need to connect the volatile compound detection means (5) to a vent pipe structure formed of other constituent members, so that heating of the volatile compound from the adsorbent (53) is not necessary. It becomes possible to perform the desorption and analysis steps precisely using equipment and equipment installed indoors.

The volatile compound adsorbent (53) used in this embodiment may be an adsorbent that exhibits hydrophobicity (hydrophobic adsorbent), considering that many volatile compounds to be detected tend to be hydrophobic. It is suitable to use from the viewpoint of improving sensitivity. Examples of the adsorbent include aromatic resins, methacrylic resins, polycarbonate resins, styrene resins, polyester resins, polyimide resins, hydrophobic silicone resins, polyphenylene sulfide resins, phenolic resins, etc. Mention may be made of carriers formed using adsorption resins.
Furthermore, as the adsorption resin, it is also possible to use modified resins obtained by modifying these resins. It is also possible to use a copolymer resin polymerized using two or more compounds belonging to these.
As for the types of resin used for the volatile compound adsorbent (53), it is also possible to use two or more of the resins listed above.

Further, as the volatile compound adsorbent (53), an embodiment is possible in which the polymer itself constituting the various hydrophobic resins described above is used as a solid phase as an adsorbent carrier. Further, it is possible to use silica gel, alumina, florisil, cellulose, or the like as a solid phase carrier, and to form an adsorbent carrier in which the various hydrophobic resins described above are bonded to the surface of the solid phase carrier.
Further, it is also possible to use silica gel, alumina, florisil, cellulose, or the like as a solid phase carrier, and form an adsorbent carrier in which various hydrophobic functional groups are bonded to the surface of the solid phase carrier. A suitable example of this embodiment is an adsorbent carrier in which various hydrophobic functional groups are bonded to the surface of silica gel. Moreover, an embodiment in which a silica gel carrier modified with an octadecyl group (ODS modification, octadecyl silylation) is used as the adsorbent carrier can be preferably mentioned. Further, an embodiment may be mentioned in which a silica gel carrier modified with an octyl group, a phenyl group, a cyanopropyl group, an aminopropyl group, etc. is used as the adsorbent carrier. Another example is an embodiment in which a silica gel carrier modified with PDMS (polydimethylsiloxane) is used as an adsorbent carrier.
It is also possible to use these as adsorbents containing carbon or activated carbon.

As for the volatile compound adsorbent (53), it is preferable to select and use an adsorbent that has excellent adsorption properties for hydrophobic compounds and is capable of thermally desorbing adsorbed components. For example, an adsorbent in which a silica monolith structure (uniform three-dimensional network structure of high-purity silica gel) is used as a solid phase and the surface of the porous structure is modified with a hydrophobic functional group can be suitably used. Further, an embodiment of the adsorbent is also possible in which the hydrophobic adsorption resin is used as a carrier as it is.
From the viewpoint of securing a surface area for efficient adsorption, the volatile compound adsorbent (53) may be filled with a particulate carrier, filter-shaped, disk-shaped, or filled with a small cylindrical ring-shaped carrier. Preferred examples include a state in which:

In the system (1) according to the present invention in this aspect, in order to more reliably detect volatile compounds contained in the gas discharged from the dehumidification section (4), the volatile compound adsorbent (53) is placed in a container. A preferred embodiment is that it is disposed inside a shaped or tubular structure (52). That is, in this embodiment, the volatile compound adsorbent (53) is connected to the dehumidifying section (4) directly or through another ventilable member to allow ventilation. (52).
The container-like or tubular structure (52) of this embodiment is connected to the downstream side of the dehumidifying section (4) directly or via another ventilable member so as to allow ventilation. In the case of this embodiment, it is possible to arrange the volatile compound adsorbent (53) at any position between the gas inlet and the gas outlet of the container-like or tubular structure (52). Preferably, a volatile compound adsorbent (53) is disposed in an air flow path between a gas inlet and a gas outlet of the container-like or tubular structure (52). More preferably, a volatile compound adsorbent (53) is filled and arranged so as to impede the flow of air between the gas inlet and the gas outlet of the container-like or tubular structure.

Examples of the container-like or tubular structure (52) include a container-like or tubular structure that is provided with a gas inlet and a gas outlet and whose wall surface is airtight. Preferably, a container-like or tubular structure in which the wall structure serves as a physical support for the member can be mentioned. Specifically, a container-like structure having a cylindrical shape or a rectangular tube shape can be mentioned. Moreover, embodiments such as a tube shape and a film bag shape can also be mentioned.
The material constituting the container-like or tubular structure (52) is not particularly limited, but it is preferably a material with excellent gas impermeability, physical strength, etc. For example, it is possible to employ the same material as the tubular or container-like structure (22) of the gas collection section described above.

[Gas suction means]
The system (1) according to the present invention preferably includes a gas suction means (6) at any downstream position of the connected structural members. That is, the system (1) according to the present invention preferably includes the gas suction means (6) as a component.

The gas suction means (6) according to the present invention provides gas flow in a ventilation channel that is connected to the end of the connected structural member directly or through another ventilable member so as to allow ventilation. This is a suction pump that allows
As for the connection position of the gas suction means (6) in the system (1) according to the present invention, the gas suction means (6) may be provided as the most downstream component of the connected components constituting the system. suitable.
More specifically, the connection position of the gas suction means (6) is the sensor part (51) of the volatile compound detection means or the tubular or container-like structure (52) in which the volatile compound adsorbent (53) is arranged. It is preferred to connect the gas suction means (6) directly or via another ventilable member to the downstream side.

The gas suction means (6) is a component including suction force generation means for driving the gas flow in the system (1) according to the present invention. By driving the gas suction means (6), gas in the soil is sucked into the pipe from the opening structure (23) of the gas collection pipe, and a gas flow is generated inside various members and the ventilation pipe, and volatile gas is removed from the soil. A gas containing a compound passes through a sensor part (51) of a volatile compound detection means or a tubular or container-like structure (52) in which a volatile compound adsorbent (53) is arranged, and finally the gas is sucked. Gas is exhausted from the exhaust port (61) of the means.
As the gas suction means (6), devices and equipment capable of realizing suction drive, such as a suction pump, a vacuum pump, an aspirator, and a decompression pump, can be used.
Regarding the performance of the gas suction means (6), it is desirable to use a gas suction means that can achieve a suction amount of, for example, 1 to 50 mL/min, preferably 5 to 10 mL/min.
As the gas suction means (6), it is preferable to use a gas suction means whose flow rate can be adjusted from the viewpoint of ensuring quantitativeness in comparison between samples. More preferably, it is even more preferable to use a gas suction means having a flow rate control function so that a constant gas flow rate is maintained.

[Other components]
The system (1) according to the present invention may include various constituent members in addition to the above-mentioned constituent members.
In the system (1) according to the present invention, it is possible to use a vent pipe (7) to connect some or all of the various components. The ventilation pipe (7) is a tubular member that allows gas to move within the tube. In the system (1) according to the present invention, soil gas introduced from the opening structure (23) of the gas collection pipe (2) passes through the interior of various structural members and then exits from the discharge port of the most downstream structural member. Vent pipes (7) can be used to connect some or all of the seed components where they are evacuated. As the ventilation pipe (7), one that is gas impermeable and has appropriate physical strength is suitable. Further, depending on the connection portion, it is possible to use a material made of a flexible material. Further, depending on the connection site, a needle-like thin ventilation pipe may be used.

Further, in the system (1) according to the present invention, it is possible to use a connecting member having a structure suitable for connection with each component. For example, it is possible to use an engagement and locking structure for connecting the ventilation structures of each member, a structure with a spiral groove, an O-ring for ensuring airtightness, etc. Further, it is also possible to cover the connecting portion with a covering member made of soft resin such as rubber to connect the connecting portion and the downstream pipe structure.
In addition, in the system (1) according to the present invention, a valve-like structure, a valve-like structure (electromagnetic valve), a plug structure, etc., which can be adjusted to open and close by external manual operation or electric signals, etc., are used as means for adjusting the ventilation flow rate. It is also possible to arrange them in a connected manner. Further, in the system (1) according to the present invention, it is also possible to provide an embodiment in which a ventilation flow rate control means is provided to automatically control the ventilation flow rate to a constant value.

In the connection mode between each component of the system (1) according to the present invention, "via another ventable member" means, for example, the above-mentioned vent pipe (7), connection member, ventilation flow rate adjustment means, ventilation Although it is possible to use members such as flow rate control members and members such as the above-mentioned filter section (3), the present invention is not particularly limited thereto.

[Aspects of the device]
In the present invention, it is possible to provide a device embodiment in which the constituent members of the system are connected to form one device. That is, the present invention includes an invention relating to an apparatus used for carrying out the above-described method for diagnosing drought stress in plants.
A device for detecting drought stress in plants according to the present invention is a device comprising a gas collection pipe (2), a dehumidifying section (4), and volatile compound detection means (5) as constituent members. By using the device according to the present invention, it becomes possible to non-destructively diagnose drought stress in plants without damaging the plants growing at the cultivation site.

Components and aspects of the device according to the present invention can be adopted with reference to the above description regarding the system.
Specifically, the device of the present invention includes, as a volatile compound detection means (5), a device for detecting volatile compounds disposed directly downstream of the dehumidifying section (4) or via another ventilable member. Mention may be made of embodiments of the device which include a sensor part (51) of the means. The configuration and aspect of the device can be adopted with reference to the description of "a mode in which direct detection is performed" among the modes of the volatile compound detection means (5) regarding the above-described system.
In this aspect of the device, it can be used as a small-sized device or device that can be used on-site, such as outdoors. Additionally, volatile compounds can be detected in real time at the cultivation site of growing plants, making it possible to diagnose drought stress in plants on the spot.

[How to use]
The following aspects can be mentioned as usage aspects of the system and device according to the present invention. Furthermore, in the following description, the term "system" can be read as "device".

The system (1) according to the present invention inserts the tip (21) of the gas collection tube into the soil near the base (82) of the plant to be diagnosed, and the opening structure (23) of the gas collection tube. ) is used in a state where it is embedded in a position placed near the root.
In the system (1) according to the present invention, as a method of inserting the gas collection pipe (2) into the soil, the opening structure of the gas collection pipe is placed at a position where gas generated from the roots of the plant to be diagnosed can be collected. Any method using (23) placed in soil can be used without any particular restrictions.

In more detail, the gas collection tube is inserted vertically from the tip (21) within 20 cm, preferably within 10 cm, from the base (82) of the plant, and the opening structure of the gas collection tube is It is desirable to use it in a state where it is embedded in soil so that (23) or its vicinity is in contact with or very close within 3 cm (preferably within 1 cm) to the roots of the plant to be diagnosed. More preferably, the gas collection tube is used in a state where the opening structure (23) is embedded in the soil so as to be in contact with the roots of the plant to be diagnosed.
The system (1) according to the present invention is used by activating the gas suction means (6) to suck the gas in the soil into the pipe through the opening structure (23) of the gas collection pipe, and It is desirable to generate a gas flow within the ventilation pipe. In particular, when this operation is performed for a certain period of time at a constant gas flow rate, it becomes possible to quantitatively collect gas from soil and detect volatile compounds, improving the accuracy of comparison between samples. suitable.
The mode of gas suction is preferably a flow rate that slowly draws gas from the soil into the pipe. For example, it is desirable to carry out at a flow rate of 1 to 50 mL/min, preferably 5 to 10 mL/min.

As the volatile compound detection means (5) of the system according to the present invention, the sensor part (51) of the volatile compound detection means is provided downstream of the dehumidification section (4) directly or through another ventilable member. In the arrangement and use mode, volatile compounds can be detected directly at the cultivation site of growing plants.
On the other hand, in an embodiment in which a volatile compound adsorbent (53) is arranged downstream of the dehumidification section (4) as the volatile compound detection means (5) of the system according to the present invention, the volatile compound adsorbent (53) is used. ), the volatile compound is recovered as a gas from the adsorbent (53) by a method such as thermal desorption, and the volatile compound is detected from the gas. In this embodiment, there is no need to connect the volatile compound detection means (5) to a vent pipe structure formed of other components, so that the thermal desorption and analysis steps from the adsorbent (53) are not necessary. , it becomes possible to perform the process precisely using equipment and equipment installed indoors.

The measured value of volatile compounds detected using the system or device according to the present invention is a value that reflects the amount of volatile compounds contained in the gas released from the roots. It can be used as the "volatile compound release amount" or "value based on the volatile compound release amount" as an index value.
In the present invention, by using the index value obtained using the system or device, the above-mentioned paragraph 1. It becomes possible to diagnose the drought stress state of plants as described in .

The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited thereto.

[Example 1] “Correlation between volatile compounds generated from roots and drought stress”
Volatile compounds released from the roots of soybeans were detected when they were cultivated under drought stress conditions.

(1) Cultivation with drought stress Soybean (variety: Sachiyutaka) seedlings grown in pots were prepared and cultivated in the following treatment plots with different rhizosphere water content by adjusting the amount of watering.
(treatment area)
Treatment plot 1-1: The rhizosphere was sufficiently humidified (pF value: 1.7 to 2.0) and cultivation was carried out in normally moisturized soil for two weeks (control plot: moisturized plot).
Treatment plot 1-2: Dry cultivation was carried out for 2 weeks with the rhizosphere pF value set at 2.7 (dry plot).
Treatment area 1-3: After 2 weeks of cultivation under a flooded condition in which the rhizosphere was submerged in water, the same cultivation as in treatment area 1-1 was carried out for 2 weeks (post-flooding moisturizing area).
Treatment area 1-4: After 2 weeks of cultivation in a flooded state where the rhizosphere was submerged in water, the same cultivation as in treatment area 1-2 was carried out for 2 weeks (dry area after flooding).
After cultivation in each treatment area, the appearance of the above-ground parts of the plants was observed, and no major differences were observed in the appearance of the above-ground parts (Figure 1).

(2) Detection of volatile compounds The roots after cultivation in each treatment area were placed in a 1L glass chamber, and the roots were placed in a 1L glass chamber using an adsorbent (MonoTrap RGPS TD, GL Science) whose porous silica monolith structure was modified with PDMS. ) for 1 hour, the volatile compounds released from the roots were adsorbed onto the adsorbent, which was then subjected to GC/MS analysis using a thermal desorption method. The GS/MS analysis was performed using the following equipment and conditions.
The volatile components (VOC) collected on the adsorbent were thermally desorbed using a thermal desorption unit (TDU, manufactured by Gestel). The thermal desorption conditions were as follows: After being held at 40°C for 30 seconds, the temperature was raised to 240°C at a rate of 12°C/second and held for 5 minutes, and carrier gas (helium) was flowed in splitless mode. The thermal desorption unit and the transfer line of the cooled injection system were set at 300°C. The temperature-programmed vaporization inlet was cooled in advance to −40° C., and volatile components (VOCs) were cryofocused in solvent vent mode at a flow rate of 60 ml/min during the thermal desorption time.
After completion of thermal desorption and at the same time as the start of GC analysis, the temperature of the injection port was rapidly raised to 240°C at a rate of 12°C/sec and held for 5 minutes to introduce volatile components (VOC) into the GC/MS system.

(Various conditions for GS/MS analysis)
Gas chromatograph mass spectrometer: Agilent 5973 (manufactured by Agilent Technologies)
Analytical column: DB-Wax (60m length, 0.25mm i.d., 0.25μm df)
Oven temperature: Hold at 40°C for 1 minute, then raise the temperature to 240°C at 4°C/min and hold for 8 minutes Carrier gas flow rate: 27cm/min (constant flow)
Mass spectrometer: scans m/z range from 20 to 400 Ionization voltage: 70eV

Comparing the chromatograms obtained by GS/MS analysis, it was found that the volatility increased in the dry plot (treated plot 1-2) compared to the control plot (treated plot 1-1) in which normal soil moisture was applied. We searched for compounds. The results are shown in the table below and Figures 2 to 4. "N.D." in the table indicates that the measured value is below the detection limit.
As a result, the plants in the dry plot (treated plot 1-2), which were grown with a lack of water in the rhizosphere, were compared to the control plot (treated plot 1-1), which was grown normally under conditions with sufficient soil moisture retention. Significantly more volatile compounds were released as gases from the roots than from the plants.
In detail, regarding the amount of released 10 types of volatile compounds shown in Figures 2 to 4, plants in the control plot (treated plot 1-1) grown under conditions with sufficient soil moisture retention were found to be more susceptible to water deprivation. It was shown that the amount of volatile compounds released as gases from the roots was significantly higher in the plants grown in the dry plot (treated plot 1-2).
In addition, the amount of release of these volatile compounds was lower in the cultivation area (treated area 1-3) where cultivation was carried out in normal moisturizing soil after being submerged in water, and in the control area (treated area 1-1). ) showed a value as low as or lower than that of the previous year. On the other hand, in the cultivation plots (treated plots 1-4) where dry cultivation was performed after submergence in water, the amount of release of these volatile compounds was higher than in the control plot (treated plots 1-1). Ta.

Eight of these ten volatile compounds are 1-hexanol, (Z)-3-hexen-1-ol, 6-methyl-5-hepten-2-one, 2-octanone, 3-octanone, It was identified as 1-penten-3-ol, hexanal, and 3-pentanone (diethyl ketone). These are compounds belonging to alcohols, aldehydes, or ketones having a carbon number of C5 to C8, and are presumed to be lipid decomposition products decomposed by promoting the production of lipid peroxide. In particular, a significant increase in 1-hexanol, (Z)-3-hexen-1-ol, and 6-methyl-5-hepten-2-one was observed under dry conditions compared to moist conditions. .
Furthermore, two of these ten types of volatile compounds were identified as compounds belonging to sesquiterpenes having peaks at 1680 and 1748 in RI value (retention time index). These are peaks corresponding to 32.46 minutes and 34.28 minutes, respectively, in terms of RT values (retention times) under the above analysis conditions. Since sesquiterpenes are known to be compounds that are secondary metabolites resulting from the activation of plant hormones, it was assumed that these are metabolites generated due to drought stress response.

The above results indicate that when the rhizosphere is in a water-deficient state during plant growth, the amount of volatile compounds released from the roots increases. This study revealed for the first time that there is a correlation between drought stress in plants and the amount of volatile compounds released from roots.
Specifically, compounds belonging to alcohols, aldehydes, and ketones with a carbon number of C5 to C8 are produced, and the amount released as gas from the roots is significantly greater than under cultivation conditions where the rhizosphere is kept moist. was shown to increase. Regarding sesquiterpenes, it was also shown that the amount released as gas from the roots increased significantly compared to cultivation conditions where the rhizosphere was kept moist.
Increases and decreases in the amount of gas released from these volatile compounds can be seen even when the cultivation conditions are submerged in water (Treatment Area 1-3, Treatment Area 1-4). It was shown that it changes accurately reflecting the moisture conditions of the area.

Based on these findings, by measuring the amount of the above-mentioned volatile compounds emitted as gas from plant roots and using it as an index, it is possible to detect drought stress in the roots even in early dry conditions where no effects are observed on the aboveground parts of the plant. It was shown that it is possible to directly detect In other words, it has been revealed that these volatile compounds emitted as gas from the roots can be used as markers for directly diagnosing the drought stress that plants are experiencing.
In particular, 1-hexanol, (Z)-3-hexen-1-ol, and 6-methyl-5-hepten-2-one are volatile compounds that show a significant increase under dry conditions compared to moist conditions. Therefore, it was recognized that it is suitable for detecting the increased amount due to drought stress and is an effective indicator compound as a diagnostic marker.

[Example 2] “Verification experiment”
The results of the above examples were verified using different varieties of soybeans.

Using soybean (variety: Fukuyutaka) seedlings grown in pots, cultivation was performed under conditions that imparted drought stress in the same manner as in Example 1, and volatile compounds released from the roots were detected.
(treatment area)
Treatment plot 2-1: The rhizosphere was sufficiently humidified (pF value: 1.7 to 2.0) and cultivation was carried out in normally moisturized soil for two weeks (control plot: moisturized plot).
Treatment plot 2-2: Dry cultivation was carried out for 2 weeks with the rhizosphere pF value set at 2.7 (dry plot).

As a result, even in the cultivation of plants other than those in Example 1, in the dry plot (treated plot 2-2), where the cultivation was carried out with the rhizosphere deficient in moisture, the control plot (treated Compared to Ward 2-1), the amount of the 10 types of volatile compounds detected in Example 1 generated from the roots increased.
These results showed that the drought stress state of plants can be detected by using the amount of volatile compounds released as gas from the roots as an index. Further, in this example as well, it was shown that it is suitable to use the 10 types of volatile compounds detected in Example 1 as indicator compounds.

[Example 3] “Construction of a plant drought stress detection system”
By creating a gas collection tube that can collect volatile compounds from plant roots in the soil and combining it with a dehumidification tube and volatile compound detection means, it is possible to directly detect drought stress in growing plants. A detection system was constructed.

A gas collection tube was manufactured as a gas collection part (2) that can be inserted into soil to collect gas in the soil, and a dry stress detection system (1) using this member was constructed. An outline of the system is shown in Figure 5.
The gas collection tube (2) is a tubular member with a circular cross section and a conical tip (21). The gas collection tube (2) has a total length of 12 cm, and the main body, the tubular structure (22), is a tubular member with an inner diameter of 14 mm and an outer diameter of 17 mm. The gas collection pipe (2) is a member in which the tip part (21) and the tubular structure (22) are integrally molded, and the wall part is made of polypropylene that does not adsorb gas components and has sufficient physical strength for insertion into soil, etc. It is made of a manufactured material.
The lower end of the gas collection tube (2) is equipped with a conical tip (21) suitable for soil insertion, and the lower end of the upper tubular structure (22) (the tip conical part (21) and the main body circular part) Three opening structures (23) capable of taking in gas in the soil are provided at positions 1 cm above the boundary of (22). The opening structure (23) is a small circular shape with a diameter of 5 mm formed on the circumference of the tube wall at equal intervals (120° intervals from the center of the tube) when viewed from the cross section of the tubular structure (22). It has a pore structure.
A soft resin connection part (24) is embedded in the center of the upper wall of the gas collection pipe (2). A needle-shaped ventilation pipe (7) is inserted and connected to the connection part (24) from the outside. The ventilation pipe (7) is connected to a filter section (3) formed of a resin cylindrical container structure (32) filled with a glass fiber filter (31). The gas collected from the soil passes through the filter section (3) to physically remove dust, particulates, and the like.

The filter section (3) is connected to a glass container (52) via a dehumidifying tube (42a) which is a dehumidifying section (4).
As the dehumidification tube (42a), a membrane drying tube (Aqua Drive, Sunsep, manufactured by AGC Engineering) with a tube length of 30 cm, an inner diameter of 1 mm, and an outer diameter of 2 mm was used. The wall portion of the dehumidifying tube (42a) is made of a fluorine-based non-porous hollow fiber membrane material. Due to the characteristics of the material that makes up the wall, when the gas passes through the tube, volatile compounds and other macromolecules contained in the gas introduced into the dehumidifying tube (42a) do not pass through the wall and become water vapor. Molecules pass through the tube wall and are released to the outside. The gas that has passed through the dehumidifying tube (42a) reduces the water vapor concentration to a concentration that does not interfere with detection of volatile compounds by GS/MS analysis or sensors.
A volatile compound adsorbent (53) is filled in a container (52) connected via a dehumidifying tube (42a). The adsorbent (53) has a porous silica monolith structure filled with a PDMS-modified carrier (Monotrap RGPS TD, GL Science). In addition, as another embodiment, a porous polymer carrier of 2.6-Diphenyl-p-phenylene Oxide (TenaxTR, manufactured by Merck & Co., Ltd.), which is a resin exhibiting hydrophobicity, and a carrier in which graphite carbon is blended with the porous polymer exhibiting hydrophobicity are also available. (TenaxGR, manufactured by Merck & Co.) is also possible.
A vent pipe (7) is further connected to the downstream side of the container (52), and a suction pump serving as gas suction means (6) is connected to the vent pipe.

The gas collection tube (2) is inserted vertically into the soil from the conical apex side of the tip (21) of the tube near the roots, about 7 cm laterally from the base (82) of the plant. used. When the gas collection tube (2) is vertically inserted, the opening structure (23) is placed very close to a portion of the root.
In the system (1), by activating the suction pump (6) and suctioning the gas in the soil, volatile compounds generated from the roots are removed through the opening structure (23) of the gas collection pipe (2). This makes it possible to collect gases containing gases. As for the operation time, for example, it is possible to carry out suction for 0.5 hours at a gas flow rate of 5 to 10 mL/min. The volatile compounds contained in the collected gas are adsorbed by the volatile compound adsorbent (53) in the container (52).
In the system (1), after the operation of the suction pump (6) is completed, the volatile compound adsorbent (53) in the container (52) is collected into a 1 L glass container, and the method described in Example 1 is performed. By similarly performing GS/MS analysis using the thermal desorption method, it becomes possible to detect volatile compounds generated from the roots.
That is, by measuring the amount of volatile compounds generated using the system (1), it is possible to detect drought stress in the roots of the target plant, and it is possible to diagnose the drought stress state of the plant body. Become.

According to the present invention, it is possible to accurately diagnose drought stress in plants at an early stage. Therefore, the present invention enables early avoidance of growth decline and physiological disorders due to water shortage in plant cultivation, and is expected to be used as a technology that will lead to improved productivity of agricultural products.

1. Plant drought stress detection system

2. Gas collection unit, gas collection pipe or gas collection container 21. Tip part 22. Tubular or container-like structure, tubular structure 23. Opening structure 24. connection part

3. Filter part 31. Filter material, glass fiber filter 32. Container-like or tubular structure

4. Dehumidification section 42. Container-like or tubular structure 42a. Tubular structure, dehumidification tube 42b. Container-like or tubular structure 43. dehumidifier

5. Volatile compound detection means 51. Sensor 52. Container-like or tubular structure 53. Volatile compound adsorbent

6. Gas suction means, suction pump 61. exhaust port

7. ventilation pipe

8. Plant body 81. Stems and leaves (aerial part)
82. Base of plant 83. Roots (underground)

9. soil

Claims (8)

A method for diagnosing drought stress in a plant to be diagnosed, comprising:
(1) A step of using the amount of volatile compounds released as gas from the roots of the plant to be diagnosed or a value based on the amount of release as an index value;
A method for diagnosing drought stress in plants, the method comprising:
;
The plant to be diagnosed is a plant belonging to soybean (Glycine max),
;
The volatile compound is a volatile compound whose amount released as a gas from the roots of plants belonging to soybean (Glycine max) increases in response to water shortage in the rhizosphere soil,
;
The volatile compound is 1-hexanol, (Z)-3-hexen-1-ol, 6-methyl-5-hepten-2-one, 2-octanone, 3-octanone, 1-penten-3-ol, Hexanal or 3-pentanone, or one or more volatile compounds selected from these volatile compounds,
;
The method for diagnosing drought stress in plants . The volatile compound is 6-methyl-5-hepten-2-one, 2-octanone, 3-octanone, 1-penten-3-ol, or 3-pentanone, or is selected from these volatile compounds. one or more volatile compounds,
;
The method for diagnosing drought stress in plants according to claim 1. After the step described in (1) above,
(2) Comparing the index value in the plant to be diagnosed with the corresponding value in a plant belonging to soybean (Glycine max) grown in moist soil as a negative control, and determining a substantial increase between the index values. a step of determining the presence or absence or degree of increase;
The method for diagnosing drought stress in plants according to claim 1, comprising: The step described in (1) above,
Using a "system for detecting volatile compounds from gases in soil," the gas released from the roots of the plant to be diagnosed is collected in the soil, the water vapor concentration of the gas is reduced, and the Detecting a volatile compound, the step comprising:
;
The "system for detecting volatile compounds from gas in soil" is a system comprising a gas collection section, a dehumidification section, and a volatile compound detection means as constituent members,
(A) A member in which the gas collection section includes a tubular or container-like structure with an opening structure for taking in gas from the soil, and the volatile compound released from the roots through the opening structure. A member capable of collecting gas containing
(B) The dehumidifying section is a member including a tubular or container-like structure connected to the gas collecting section so as to be ventilated directly or through another ventilable member, and the dehumidifying section A member that can dehumidify water vapor contained in the gas inside the
(C) The volatile compound detection means detects a volatile compound contained in the gas that has passed through the dehumidification section, or a volatile compound that has been adsorbed by a volatile compound adsorbent from the gas that has passed through the dehumidification section. is a device or equipment capable of
;
The method for diagnosing drought stress in plants according to claim 1 . Regarding the "system for detecting volatile compounds from gas in soil" used in the method for diagnosing drought stress of plants according to claim 4,
;
The gas collection unit according to (A) is a member including a tubular structure having a tip portion into which soil can be inserted and an opening structure for taking in gas.
;
The method for diagnosing drought stress in plants according to claim 4 . Regarding the "system for detecting volatile compounds from gas in soil" used in the method for diagnosing drought stress of plants according to claim 4,
;
The system includes a gas suction means as a component,
(D) the gas suction means is connected to the end of the connected component in a ventilable manner, either directly or through another ventilable member, to enable gas flow in a ventilation channel; is a suction pump that
;
The method for diagnosing drought stress in plants according to claim 4 . Regarding the "system for detecting volatile compounds from gas in soil" used in the method for diagnosing drought stress of plants according to claim 4,
;
The system includes a volatile compound adsorbent as a component,
(E) The volatile compound adsorbent is disposed inside a tubular or container-like structure that is connected to the dehumidifying section so as to allow ventilation, either directly or through another ventilable member. can be,
;
The volatile compound detection means described in (C) above is a device or equipment that is not connected as a ventilation channel to the above-mentioned constituent members, and is capable of detecting volatile compounds adsorbed by the volatile compound adsorbent. A device or device that can be detected by thermal desorption;
;
The method for diagnosing drought stress in plants according to claim 4 . Regarding the "system for detecting volatile compounds from gas in soil" used in the plant drought stress diagnosis method according to claim 4,
;
Regarding the volatile compound detection means described in (C) above, the sensor portion of the volatile compound detection means is connected to the dehumidifying section so as to allow ventilation directly or through another ventilable member. A device or device that is placed inside a tubular or container-like structure and is capable of detecting volatile compounds contained in gas at the sensor portion.
;
The method for diagnosing drought stress in plants according to claim 4 .

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