Method for evaluating drought tolerance of different plant species

Abstract

The invention discloses a method for evaluating drought tolerance of different plant species, which comprises the following steps: taking at least two different plants as experimental subjects, and measuring basic parameters of each experimental subject; the internal temperature and humidity of the experiment container are adjusted, and the drought condition of the plant is simulated; sequentially putting each experiment object into an experiment container, regulating and controlling according to a preset temperature gradient, observing and recording the degree change of the temperature and humidity sensor in each time period, and obtaining the temperature and humidity of each stage of each experiment object; calculating absolute humidity changing along with temperature and time change in the experiment container, calculating a water evaporation rate of the branch in unit area based on a difference value of the absolute humidity, and obtaining Wdroughts of various experiment objects at different temperatures; based on the Wdroughts of the experimental subject at different temperatures, the phase transition temperature Tp of the experimental subject is obtained. The method has the advantages that the water loss speed of plants passing through cuticles and other non-stomatal ways after stomata closing can be quantified, and the method is of great importance for evaluating the risk of tree death caused by drought.

Description

Technical Field

[0001] The invention relates to the technical field of evaluation of the impact of drought events on plants, and in particular to a method for evaluating the drought resistance of different plant species. Background Art

[0002] In most species under non-limiting water conditions, stomata open during the day to capture atmospheric carbon dioxide for photosynthesis while losing water through transpiration. To avoid drought, plants close their stomata to reduce the rate of water loss. However, even with stomata closed, plants continue to lose water through the leaf cuticle, leaky stomata, and bark. The rate of water loss in the face of drought stress determines the time it takes for the plant water potential to reach the hydraulic failure threshold. min (minimum conductance) varies among species. min The threshold point at which the increase is significant is called the phase transition temperature (T p ), which corresponds to the temperature at which changes in the cuticle wax structure lead to an increase in the permeability of the cuticle and can therefore serve as a proxy for the ability of plants to resist uncontrolled and rapid dehydration leading to uncontrolled embolism during periods of high temperature.

[0003] Currently, the most widely used assay is W min The method is to repeatedly measure the dehydration of detached leaves on the laboratory bench. However, this method is interfered by many factors, making it difficult to evaluate W. min The temperature response and determination of T p The key is that during drought, the water loss of plant branches through the bark also exists. Although the specific contribution is not clear, it is obviously unreasonable to only consider the water loss of leaves. Therefore, how to eliminate the interference of extraneous external factors and reduce the error in measuring the water loss of branches under drought stress, and judge W accordingly. min The threshold point of significant increase, namely the phase transition temperature, is used to evaluate the drought response strategies and characteristics of species, which is an urgent issue to be addressed. Summary of the invention

[0004] The object of the present invention is to provide a method for evaluating drought tolerance of different plant species, thereby solving the above-mentioned problems existing in the prior art.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

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

[0007] S1. Use at least two different plants as experimental subjects and measure the leaf area, stem length and base diameter of each experimental subject;

[0008] S2. Setting up an experimental container, adjusting the internal temperature and humidity of the experimental container, and simulating the drought conditions to which the plants are subjected;

[0009] S3, placing each experimental object into the experimental container in turn, regulating it according to the preset temperature gradient, observing and recording the changes in the temperature and humidity sensors at each time period, and obtaining the temperature and humidity of each experimental object at each stage;

[0010] S4. Calculate the absolute humidity in the experimental container as it changes with temperature and time, and 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:

[0011] S41. Calculate the saturated water vapor pressure at different temperatures in each stage of the experimental container:

[0012]

[0013] Among them, E S (T) is the saturated water vapor pressure; T is the temperature in the experimental container;

[0014] S42. Calculate the absolute humidity of the experimental container at different temperatures at each stage:

[0015]

[0016] 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 Kelvin temperature; AH is absolute humidity;

[0017] S43. Calculate the water mass loss of the experimental container at each stage and the water transpiration rate per unit area of ​​the branches:

[0018]

[0019] 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;

[0020] 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:

[0021]

[0022]

[0023] 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;

[0024] S45. Calculate W at different temperature gradients drought Rate of change:

[0025]

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

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

[0028] Preferably, step S1 specifically comprises the following steps: selecting at least two different plants as experimental subjects; for each plant, collecting branches with a length of 0.8 to 1 m from a height of 2 to 3 m of 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 from the tip 25 to 30 cm, 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.

[0029] Preferably, the experimental container is a sealed container, in which a temperature and humidity sensor and a heating resistor are installed; 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 the experimental container is used, it is necessary to check whether the inside of the detector has good airtightness.

[0030] Preferably, dry and clean air is introduced into the experimental container, and the internal temperature is adjusted to 30° C. and the humidity is adjusted to 40% to simulate the drought conditions to which the plants are subjected.

[0031] Preferably, step S3 is specifically as follows: various experimental objects are placed in the experimental container in turn 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°C, 35°C, 40°C, 45°C, 50°C, and 55°C, and each temperature is maintained for 1 hour, and the temperature, humidity and time taken at the beginning and end of the heating stage, as well as the temperature and humidity at the beginning and end of the constant temperature stage are recorded to obtain the temperature and humidity of various plants at various stages.

[0032] Preferably, step S5 specifically includes, for each experimental object, drawing its W drought Temperature dependence diagram of W drought The rate of change diagram under different temperature gradients determines the T of each experimental object p .

[0033] The beneficial effect of the present invention is that the present invention can be used to detect the water loss rate of plants under the condition of stomata closure caused by drought stress and the phase transition temperature corresponding to the threshold point of mutation. The present invention pays more attention to the speed of water loss of plants through the cuticle and other non-stomatal pathways for the impact of drought stress on plants, and takes into account 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 invention helps to quantify the speed of water loss of plants through the cuticle and other non-stomatal pathways after stomata closure, which is crucial for assessing the risk of tree death caused by drought. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flow chart of a method in an embodiment of the present invention;

[0035] Figure 2 In the embodiment of the present invention, W drought Temperature dependence of W drought Graph of the rate of change under different temperature gradients. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not used to limit the present invention.

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

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

[0039] The sycamore trees (deciduous trees, angiosperms), cypress trees (evergreen trees, gymnosperms), and metasequoia trees (deciduous trees, gymnosperms) were used as experimental subjects. Branches about 1 meter long were collected from 2 to 3 meters high of the three trees that were growing well and had no obvious diseases, and were packed in large plastic bags and transported to the laboratory. The end of each branch should be re-cut and soaked in water overnight. At the same time, the top of the branch was sealed in a plastic bag and stored in dark conditions to achieve full hydration. Before the formal experiment, each branch was cut from about 30 cm from the tip, and the cut end was sealed with paraffin. Then the leaf area on each branch and the stem length and base diameter of the branch were measured.

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

[0041] A sealed container is set up, and an air temperature and humidity sensor is installed inside to monitor the real-time temperature and humidity changes in the container, as well as a heating resistor to adjust the internal temperature. Finally, whether the inside of the container is well sealed is detected.

[0042] 3. Adjust the temperature and humidity inside the container to simulate the drought conditions to which the plants are exposed.

[0043] Dry and clean air is introduced into the device, the temperature is adjusted to 30℃, and the humidity is maintained at 40%, which can preliminarily simulate drought conditions. Put a sycamore branch in the container and fix it on the top of the container, and record the temperature and humidity at this moment as the initial value.

[0044] 4. Adjust the temperature according to the preset temperature gradient, observe and record the changes in the humidity sensor's readings at each time period.

[0045] The air temperature gradient inside the experimental container was set to 30°C, 35°C, 40°C, 45°C, 50°C, and 55°C, and each temperature was maintained for 1 h. The temperature, humidity, and time at the beginning and end of the heating stage, as well as the temperature and humidity at the beginning and end of the constant temperature stage were recorded.

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

[0047] Repeat the above steps and carry out the same test process on the cypress and metasequoia branches, and record the temperature and humidity of the three varieties of plants at each stage.

[0048] 6. Use the formula to calculate the absolute humidity in the container that changes with temperature and time, and use the difference in absolute humidity to calculate the water evaporation rate per unit area of ​​the branches, and obtain the W of the experimental object at different temperatures. drought (rate at which a branch loses water when its stomata are closed).

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

[0050]

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

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

[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 Kelvin temperature; AH is absolute humidity (g / m 3 )

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

[0056] Constant temperature stage:

[0057]

[0058] 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 area of ​​all leaves on the i-th branch and the surface area of ​​the stem (calculated from the stem length and base diameter, assuming it is a cone).

[0059] (4) Calculate the saturated water vapor pressure difference at each stage and the rate at which the branches lose water when the stomata are closed:

[0060]

[0061] Among them, W drought is the rate at which branches lose water when their stomata are closed; E is the rate at which water per unit area of ​​branches evaporates; VPD is the saturated vapor pressure difference.

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

[0063]

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

[0065] 7. Draw W drought Temperature dependence diagram of W drought The rate of change diagram under different temperature gradients determines 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 and related parameters of the data, 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 evaluating the drought tolerance of different plants. The present invention can be used to detect the water loss rate of plants under the condition of stomata closure caused by drought stress and the phase transition temperature corresponding to the threshold point of mutation. The present invention focuses more on the rate at which plants lose water through the cuticle and other non-stomatal pathways for the impact of drought stress on plants, and takes into account 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 invention helps to quantify the rate at which plants lose water through the cuticle and other non-stomatal pathways after stomata closure, which is crucial for assessing the risk of tree death caused by 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 principle of the present invention. These improvements and modifications should also be considered as 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, adjusting the internal temperature and humidity of the experimental container, and simulating the drought conditions to which the plants are subjected; S3, placing each experimental object into the experimental container in turn, regulating it according to the preset temperature gradient, observing and recording the changes in the temperature and humidity sensors at each time period, and obtaining 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, and 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 Kelvin temperature; AH is 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, used to characterize W drought The rate of change of W drought,j and W drought,j+1 are W corresponding to the jth temperature and 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 m from a height of 2 to 3 m of 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 a formal experiment, each branch is cut from the tip 25 to 30 cm, 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, in which a temperature and humidity sensor and a heating resistor are installed; 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 the experimental container is used, it is necessary to check whether the inside of the detector has good airtightness.

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

5. The method for evaluating drought tolerance of different plant species according to claim 1, characterized in that: 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°C, 35°C, 40°C, 45°C, 50°C, and 55°C, and each temperature is maintained for 1 hour, and the temperature, humidity and time taken at the beginning and end of the heating stage, as well as the temperature and humidity at the beginning 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, characterized in that: Step S5 specifically includes, for each experimental object, drawing its W drought Temperature dependence diagram of W drought The rate of change diagram under different temperature gradients determines the T of each experimental object p .

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