A method for assessing drought tolerance of different plant species

Abstract

The application discloses a method for evaluating drought tolerance of different plant species, which comprises the following steps: taking at least two different plants as experimental objects, measuring basic parameters of each experimental object; adjusting the internal temperature and humidity of an experimental container to simulate drought conditions to which the plants are subjected; sequentially placing each experimental object into the experimental container, controlling according to a preset temperature gradient, observing the degree change of the temperature and humidity sensor in each time period and recording, and obtaining the temperature and humidity of each experimental object in each stage; calculating the absolute humidity in the experimental container which changes with temperature and time, calculating the water evaporation rate on the unit area of the branch based on the difference of the absolute humidity, obtaining the W drought of each experimental object under different temperatures drought , and obtaining the phase transition temperature T p of each experimental object under different temperatures. The method has the advantages that it is helpful to quantifying the speed of water loss of plants through the cuticle and other non-stomatal pathways after the stomata are closed, and is crucial for evaluating the risk of tree death caused by drought.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drought event impact assessment on plants, and particularly relates to a method for evaluating drought tolerance of different plant species. BACKGROUND

[0002] In most species under non-limiting water conditions, stomata open during the day to take in atmospheric carbon dioxide for photosynthesis, while water is lost due to transpiration. To avoid drought, plants will close stomata to reduce water loss rate. However, even in the case of stomata closure, plants will continue to lose water through leaf cuticle, leaky stomata and bark. The rate of water loss under drought stress determines the time for plant water potential to reach the hydraulic failure threshold. min (minimum conductance) varies between different species, when W min The threshold point of significant increase is called the phase transition temperature (T p ), which corresponds to the temperature at which the waxy structure of the cuticle changes, resulting in an increase in cuticle permeability, and thus can be used as an indicator of the plant's ability to resist uncontrolled and rapid dehydration leading to uncontrolled embolism during high temperature periods.

[0003] Currently, the most widely used method for determining W min is to repeatedly measure the dehydration of detached leaves in the laboratory, however, this method is subject to interference from various factors, making it difficult to assess the temperature response of W min and determine T p The most critical issue is that water loss through the bark of plant branches also occurs during drought, although the exact contribution is not clear, but it is obviously unreasonable to only consider the water loss of leaves, so how to exclude the interference of external factors, reduce the error of determining the water loss of branches under drought stress, and thus determine the threshold point of significant increase of W min , i.e. the phase transition temperature, to evaluate the drought response strategy and characteristics of the species, is a problem that needs to be solved. SUMMARY

[0004] The present application aims to provide a method for evaluating drought tolerance of different plant species, thereby solving the aforementioned problems in the prior art.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0006] A method for evaluating drought tolerance of different plant species, comprising the following steps,

[0007] S1, using at least two different plants as experimental objects, measuring the leaf area, branch stem length and base diameter of each experimental object;

[0008] S2, set up the experimental container, adjust the internal temperature and humidity of the experimental container, simulate the drought condition received by the plant;

[0009] S3, sequentially put each experimental object into the experimental container, control according to the preset temperature gradient, observe the degree change of the temperature and humidity sensor in each time period and record, and obtain the temperature and humidity of each stage of various experimental objects;

[0010] S4, calculate the absolute humidity in the experimental container changing with temperature and time, calculate the water evaporation rate on the unit area of the branch based on the difference of the absolute humidity, and obtain the W drought of various experimental objects under different temperatures; the calculation process of step S4 is specifically,

[0011] S41, calculate the saturation water vapor pressure under different temperatures in each stage of the experimental container:

[0012]

[0013] Wherein, E S (T) is the saturation water vapor pressure; T is the temperature in the experimental container;

[0014] S42, calculate the absolute humidity under different temperatures in each stage of the experimental container:

[0015]

[0016] Wherein, RH is the relative humidity in the experimental container; M W is the molar mass of water vapor; R is the ideal gas constant; T k is the Kelvin temperature; AH is the absolute humidity;

[0017] S43, calculate the water mass loss in each stage of the experimental container and the water transpiration rate on the unit area of the branch:

[0018]

[0019] Wherein, Δn w is the water mass loss in the constant temperature stage; t c is the time length of the constant temperature stage; ΔAH is the change amount of the absolute humidity; V is the volume of the experimental container; E is the water transpiration rate on the unit area of the branch; S leaf,i and S stem,i are the surface area and stem surface area of all leaves on the ith branch, respectively;

[0020] S44, calculate the saturation water vapor pressure difference and the water loss rate of the branch in the closed state of the stomata in each stage:

[0021]

[0022]

[0023] wherein W drought is the rate of water loss from the branch in the stomata closed state; E is the rate of water transpiration per unit area of the branch; VPD is the saturated water vapor pressure difference;

[0024] S45, the rate of change of W drought under different temperature gradients is calculated:

[0025]

[0026] wherein W j is the rate of change of the reaction between temperature gradients, used to represent the rate of change of W drought ; W drought,j and W drought,j+1 are W drought corresponding to the jth temperature and the j+1th temperature respectively; T j and T j+1 are the jth temperature and the j+1th temperature respectively.

[0027] S5, based on the W drought of each experimental object at different temperatures, the phase transition temperature T p of each experimental object is obtained.

[0028] Preferably, step S1 is specifically selecting at least two different plants as experimental objects; for each plant, a branch with a length of 0.8-1m is collected from a well-grown plant without obvious diseases at a height of 2-3m, and is packed in a large plastic bag and transported to the laboratory; the end of each branch should be cut again and soaked in water overnight, while the top of the branch is sealed in a plastic bag and stored in dark conditions to achieve full hydration; before the formal experiment, each branch is cut from the tip 25-30cm, the cut end is sealed with paraffin, and then the leaf area, stem length and base diameter of each branch are measured.

[0029] Preferably, the experimental container is a sealed container, which is internally provided with a temperature and humidity sensor and a heating resistor; the temperature and humidity sensor is used to monitor the real-time temperature and humidity changes inside the experimental container, and the heating resistor is used to adjust the temperature inside the experimental container; before use, the detector needs to be detected whether it has good airtightness.

[0030] Preferably, dry and clean air is introduced into the experimental container, and the internal temperature is adjusted to 30℃ and the humidity is adjusted to 40% to simulate the drought conditions suffered by the plant.

[0031] Preferably, step S3 is specifically that the various experimental objects are sequentially placed in the experimental container and fixed on the top thereof, and the temperature and humidity at this moment are recorded as initial values; the internal air temperature gradient of the experimental container is set to 30℃, 35℃, 40℃, 45℃, 50℃ and 55℃, each temperature is kept for 1h, and the temperature, humidity and time used at the start and end of the warming stage and the temperature and humidity at the start and end of the constant temperature stage are recorded to obtain the temperature and humidity of each stage of the various plants.

[0032] Preferably, step S5 is specifically that, for each experimental object, a temperature-dependent graph of W drought and a rate graph of W drought at different temperature gradients are drawn to determine the T p of each experimental object.

[0033] The present application has the beneficial effect that it can be used to detect the water loss rate of plants under drought stress leading to stomatal closure and the threshold point of the phase transition temperature corresponding to the mutation. The present application pays more attention to the speed of water loss of plants through the cuticle and other non-stomatal pathways under drought stress, and considers the water loss of plant branches through the bark during drought, which is crucial for understanding the drought tolerance of different plant species. The present application helps to quantify the speed of water loss of plants through the cuticle and other non-stomatal pathways after stomatal closure, which is crucial for assessing the risk of tree death caused by drought. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a flowchart of the method in the embodiment of the present application;

[0035] Figure 2 is a temperature-dependent graph of W drought and a rate graph of W drought at different temperature gradients. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0037] As shown in Figure 1 , in the embodiment, a method for evaluating the drought tolerance of different plant species is provided, which specifically includes the following contents,

[0038] 1. Obtain experimental materials and perform basic treatment, measure leaf area, branch stem length and base diameter.

[0039] The tree branches of 1 meter long were collected from the height of 2 to 3 meters of the trees of Platanus orientalis (deciduous tree, angiosperm), Cupressus funebris (evergreen tree, gymnosperm), and Metasequoia glyptostroboides (deciduous tree, gymnosperm) with good growth and no obvious disease, and were transported to the laboratory in a large plastic bag. The end of each branch should be cut again and soaked in water overnight, while the top of the branch is sealed in a plastic bag and stored in the dark to achieve sufficient hydration. Before the formal experiment, each branch is cut from about 30 cm from the tip, and the cut end is sealed with paraffin. Then the leaf area of each branch, the stem length and the base diameter are measured.

[0040] 2. Set up the experimental container, install the temperature and humidity sensor and heating resistance.

[0041] A sealed container is set up, which is equipped with air temperature and humidity sensors inside to monitor the real-time temperature and humidity changes in the container, and is equipped with a heating resistance to adjust the internal temperature. Finally, it is detected whether the container has good airtightness.

[0042] 3. Adjust the temperature and humidity inside the container to simulate the drought conditions experienced by plants.

[0043] Dry and clean air is introduced into the device, and the temperature is adjusted to 30°C and the humidity is maintained at 40%. Such conditions can preliminarily simulate drought conditions. The Platanus orientalis branches are placed in the container and fixed at the top of the container, and the temperature and humidity at this moment are recorded as the initial values.

[0044] 4. The temperature gradient is controlled according to the preset temperature gradient, and the degree change of the humidity sensor at each time period is observed and recorded.

[0045] The air temperature gradient in the experimental container is set to 30°C, 35°C, 40°C, 45°C, 50°C, and 55°C, each temperature is maintained for 1 hour, and the temperature, humidity and time used at the beginning and end of the temperature rising stage, and the temperature and humidity at the beginning and end of the constant temperature stage are recorded.

[0046] 5. Repeat the above process for each variety of experimental material.

[0047] Repeat the above steps, and the Cupressus funebris and Metasequoia glyptostroboides branches are also subjected to the above test process, and the temperature and humidity of the three varieties of plants at each stage are recorded.

[0048] 6. Calculate the absolute humidity in the container that changes with temperature and time using the formula, and calculate the water evaporation rate per unit area of the branch using the difference in absolute humidity, and obtain the W drought (of the branch in the closed state) at different temperatures.

[0049] (1) Calculate the saturated water vapor pressure at different temperatures in each stage of the container:

[0050]

[0051] Where, E S (T) is the saturated water vapor pressure; T is the temperature in the experimental container (in Celsius).

[0052] (2) Calculate the absolute humidity at different temperatures in each stage of the container

[0053]

[0054] Where, RH is the relative humidity in the experimental container; M W is the molar mass of water vapor; R is the ideal gas constant; T k is the Kelvin temperature; AH is the absolute humidity (g / m 3 )

[0055] (3) Calculate the water mass loss in each stage of the container and the water transpiration rate per unit area of the branch:

[0056] Constant temperature stage:

[0057]

[0058] Where, Δn w is the water mass loss in the constant temperature stage; t c is the duration of the constant temperature stage; ΔAH is the change in absolute humidity; V is the volume of the experimental container; E is the water transpiration rate per unit area of the branch; S leaf,i and S stem,i are the surface areas of all leaves and stems (calculated from stem length and base diameter, assuming a conical shape) on the i-th branch, respectively.

[0059] (4) Calculate the saturated water vapor pressure difference and the rate at which the branch loses water in the closed stomata state in each stage:

[0060]

[0061] Where, W drought is the rate at which the branch loses water in the closed stomata state; E is the water transpiration rate per unit area of the branch; VPD is the saturated water vapor pressure difference.

[0062] (5) Calculate the rate of change of W drought under different temperature gradients to facilitate the identification of the interval of T p :

[0063]

[0064] Among them, W j is the reaction rate between temperature gradients, which is used to characterize W drought The rate of change of W drought,j and W drought,j+1 W corresponding to the jth temperature and the j+1th temperature respectively drought ;T j and T j+1 are the jth temperature and the j+1th temperature respectively.

[0065] 7. Draw W drought Temperature dependence diagram of W drought The rate of change diagram under different temperature gradients was used to determine the T of each plant. p (Phase transition temperature).

[0066] Based on the calculated data, draw Figure 2 The temperature dependence diagram shown and W drought The rate of change graph under different temperature gradients makes the data easier to analyze and interpret, and it is easier to determine the trend of the data and related parameters, which is convenient for determining T p interval.

[0067] By adopting the above technical solution disclosed in the present invention, the following beneficial effects are obtained:

[0068] The present invention provides a method for assessing the drought tolerance of different plant species. This method can be used to measure the water loss rate of plants under drought stress-induced stomatal closure, as well as the phase transition temperature corresponding to the threshold point of the mutation. The present invention focuses on the rate of water loss through the cuticle and other non-stomatal pathways in the impact of drought stress on plants, and also considers water loss through the bark of plant branches during drought, which is crucial for understanding the drought tolerance of different plant species. This method helps quantify the rate of water loss through the cuticle and other non-stomatal pathways after stomatal closure, which is crucial for assessing the risk of tree mortality due to drought.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for evaluating drought tolerance of different plant species, characterized in that: The following steps are included: S1. Use at least two different plants as experimental subjects and measure the leaf area, stem length and base diameter of each experimental subject. S2. Setting up an experimental container and adjusting the internal temperature and humidity of the experimental container to simulate the drought conditions to which the plants are subjected; S3. Place each experimental object in the experimental container in turn, adjust the temperature according to the preset temperature gradient, observe and record the changes in the temperature and humidity sensor at each time period, and obtain the temperature and humidity of each experimental object at each stage; S4. Calculate the absolute humidity in the experimental container as it changes with temperature and time. Calculate the water evaporation rate per unit area of ​​the branches based on the difference in absolute humidity to obtain the W of various experimental objects at different temperatures. drought ; The calculation process of step S4 is specifically as follows, S41. Calculate the saturated water vapor pressure at different temperatures in each stage of the experimental container: Among them, E S (T) is the saturated water vapor pressure; T is the temperature in the experimental container; S42. Calculate the absolute humidity of the experimental container at different temperatures at each stage: Where RH is the relative humidity in the experimental container; M W is the molar mass of water vapor; R is the ideal gas constant; T k is the Kelvin temperature; AH is the absolute humidity; S43. Calculate the water mass loss of the experimental container at each stage and the water transpiration rate per unit area of ​​the branches: Among them, Δn w is the water mass loss in the constant temperature stage; t c is the duration of the constant temperature stage; ΔAH is the change in absolute humidity; V is the volume of the experimental container; E is the rate of water transpiration per unit area of ​​the branches; S leaf,i and S stem,i are the surface areas of all leaves and stems on the i-th branch respectively; S44. Calculate the saturated water vapor pressure difference at each stage and the rate at which the branches lose water when the stomata are closed: Among them, W drought is the rate at which branches lose water when stomata are closed; E is the rate of water transpiration per unit area of ​​branches; VPD is the saturated vapor pressure difference; S45. Calculate W at different temperature gradients drought Rate of change: Among them, W j is the reaction rate between temperature gradients, which is used to characterize W drought The rate of change of W drought,j and W drought,j+1 W corresponding to the jth temperature and the j+1th temperature respectively drought ;T j and T j+1 are the jth temperature and the j+1th temperature respectively; S5, based on the W of each experimental object at different temperatures drought , obtain the phase transition temperature T of each experimental object p .

2. The method for evaluating drought tolerance of different plant species according to claim 1, characterized in that: Step S1 specifically includes selecting at least two different plants as experimental subjects; for each plant, collecting branches with a length of 0.8 to 1 meter from a height of 2 to 3 meters from plants that are growing well and have no obvious diseases, and transporting them to the laboratory in large plastic bags; the end of each branch should be re-cut and then soaked in water overnight, while the top of the branch is sealed in a plastic bag and stored in dark conditions to achieve full hydration; before conducting the formal experiment, each branch is cut 25 to 30 cm from the tip, the cut end is sealed with paraffin, and then the leaf area on each branch and the stem length and base diameter of the branch are measured.

3. The method for evaluating drought tolerance of different plant species according to claim 1, characterized in that: The experimental container is a sealed container, which is equipped with a temperature and humidity sensor and a heating resistor. The temperature and humidity sensor is used to monitor the real-time temperature and humidity changes inside the experimental container, and the heating resistor is used to adjust the temperature inside the experimental container. Before using the experimental container, the detector needs to check whether the interior is well sealed.

4. The method for evaluating drought tolerance of different plant species according to claim 1, wherein: Dry and clean air was introduced into the experimental container, and the internal temperature was adjusted to 30°C and the humidity to 40% to simulate the drought conditions suffered by the plants.

5. The method for evaluating drought tolerance of different plant species according to claim 1, wherein: Step S3 is specifically as follows: various experimental objects are placed in the experimental container in turn and fixed on the top, and the temperature and humidity at this moment are recorded as the initial values; the internal air temperature gradient of the experimental container is set to 30℃, 35℃, 40℃, 45℃, 50℃, and 55℃, and each temperature is maintained for 1 hour. The temperature, humidity and time at the start and end of the heating stage, as well as the temperature and humidity at the start and end of the constant temperature stage are recorded to obtain the temperature and humidity of various plants at various stages.

6. The method for evaluating drought tolerance of different plant species according to claim 1, wherein: Step S5 specifically involves drawing W for each experimental object. drought Temperature dependence diagram of W drought The rate of change diagram under different temperature gradients is used to determine the T of each experimental object. p .

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