Crop salt stress diagnosis method based on canopy temperature

Abstract

The invention discloses a crop salt stress diagnosis method based on canopy temperature, and relates to the field of agriculture. The method comprises the following steps: acquiring the canopy temperature of a crop without salt stress and the canopy temperature of a crop to be diagnosed; according to the canopy temperature of the salt-stress-free crop and the canopy temperature of the crop to be diagnosed, the temperature above stress is obtained through calculation; and evaluating the salt stress degree of the to-be-diagnosed crop through the temperature above the stress-free temperature. The crop salt stress diagnosis method provided by the invention is simple, rapid and easy to operate, high-throughput monitoring is convenient to realize, the corn salt stress degree can be diagnosed through the canopy temperature-based temperature above unstressed temperature, and a new method is provided for guiding the planting and production of crops.

Description

Technical Field

[0001] The invention relates to the field of agriculture, and in particular to a crop salt stress diagnosis method based on canopy temperature. Background Art

[0002] At present, salt stress is an abiotic stress factor that seriously affects seed germination, crop growth and development, and seriously threatens corn yield. In addition, due to improper crop irrigation management, over-fertilization and over-cultivation, as well as natural reasons such as sea level rise, the area of ​​saline-alkali land has increased year by year, bringing serious harm to agricultural production. Therefore, a fast, real-time, highly accurate and plant-safe salt stress diagnosis method is very important for disaster prevention and loss reduction and field management.

[0003] In the existing technology, the latest technical solution is the "crop water stress index" model based on canopy temperature, namely the CWSI empirical model, which can be used for crop salt stress diagnosis. The no stress baseline (NWSB) and no transpiration baseline (NTB) are used to describe the canopy temperature difference of two extreme conditions of crops as the upper and lower limits, respectively. The calculation formula is:

[0004]

[0005] Where CWSI is the crop water stress index, d Tm is the corn canopy T to be tested c and air temperature T a The difference, d TLL and d TUL are the lower limit and upper limit of the crown air temperature difference respectively; the lower limit and upper limit of the crown air temperature difference are calculated as follows:

[0006] dT LL =m*VPD+b

[0007] dT UL =m*VPG+b

[0008] VPD=e s (T a )-e a

[0009]

[0010] VPG=e s (T a )-e s (T a +b)

[0011] Where m and b are the slope and intercept of the fitted NWSB, VPG is the saturated vapor pressure gradient, and e is s (T a) is the saturated water vapor pressure corresponding to the air temperature, e a is the actual water vapor pressure and RH is the relative humidity of the air.

[0012] It can be seen that the above crop water stress diagnosis model is computationally complex and relies on multiple parameters such as crop canopy temperature, air temperature and water vapor pressure. Although it can effectively diagnose crop stress, its method is not easy to operate and difficult to achieve high-throughput monitoring. In addition, soil salt stress is becoming more and more frequent, seriously threatening agricultural production, and there is a relative lack of non-destructive and rapid diagnosis methods for salt stress.

[0013] Therefore, how to detect and judge the salt stress status of crops quickly, with high throughput and without damage is an issue to be solved. Summary of the invention

[0014] Based on this, it is necessary to provide a crop salt stress diagnosis method based on canopy temperature to address the above technical issues.

[0015] The present invention adopts the following technical solutions:

[0016] The present invention provides a method for diagnosing crop salt stress based on canopy temperature, comprising:

[0017] Obtaining the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed; the crop without salt stress and the crop to be diagnosed are under the same growth environment conditions and irrigation scenario;

[0018] The temperature above no stress is determined by the difference between the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed;

[0019] The salt stress degree of the crop to be diagnosed is evaluated by measuring the temperature above the no-stress level.

[0020] Preferably, the crops to be diagnosed include corn, rice and wheat; the growth periods of the crops to be diagnosed include the trumpet stage, tasseling stage and milky stage.

[0021] Preferably, the salt-free stress is that no additional salt is added, and the initial salt concentration of the soil is 0.07%; the salt stress environment is that salt is added so that the soil salt content within a depth of 1m in the test site is 0.2%; the irrigation scenarios include: normal irrigation, mild deficit irrigation and moderate deficit irrigation.

[0022] Preferably, the acquisition of the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed comprises the following steps:

[0023] Place the infrared thermometer probe 60 cm above the crop canopy;

[0024] Select clear and cloudless weather conditions and specify the monitoring time of the infrared thermometer to be from 13:00 to 14:00 Beijing time;

[0025] During the specified monitoring time, the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed are obtained every 15 minutes.

[0026] Preferably, the temperature above the stress-free temperature is obtained by the following calculation formula:

[0027] DANS=T s -T ns

[0028] Where DANS is the temperature above which no stress is observed, T s is the canopy temperature of the crop to be diagnosed, T ns is the canopy temperature of the unstressed crop.

[0029] Preferably, the step of evaluating the salt stress degree of the crop to be diagnosed by a temperature above the no-stress temperature comprises:

[0030] When crops are under no salt stress conditions, the canopy temperature is lower than or close to the ambient temperature through effective transpiration heat dissipation; when crops are under salt stress conditions, salt inhibits the opening of the crop's stomata, reduces the transpiration rate, and limits the canopy's heat dissipation function, causing the canopy temperature to rise.

[0031] According to the canopy temperature characteristics of crops under no salt stress conditions and the canopy temperature characteristics of crops under salt stress conditions, it is determined that there is a positive correlation between the temperature above no stress and the degree of salt stress suffered by crops;

[0032] Based on the positive correlation, the difference between the canopy temperature of crops under non-salt stress conditions and the canopy temperature of crops under salt stress conditions can be monitored to diagnose the degree of salt stress of crops.

[0033] Preferably, the method of evaluating the salt stress degree of the crop to be diagnosed by using a temperature above the no-stress temperature further comprises:

[0034] If the temperature above no stress is greater than 0, it means that the crop to be diagnosed has salt stress, and the larger the value of the temperature above no stress is, the more serious the salt stress of the crop to be diagnosed is, and vice versa;

[0035] If the temperature above no stress is less than or equal to 0, it means that the crop to be diagnosed does not have salt stress.

[0036] Preferably, the method of evaluating the salt stress degree of the crop to be diagnosed by using a temperature above the no-stress temperature further comprises:

[0037] Setting a baseline of no salt stress and salt stress conditions for the crop to be diagnosed;

[0038] Measure the morphological and physiological parameters of crops at different growth stages under salt stress conditions;

[0039] Obtain the changes in the morphological and physiological parameters of crops under different salt stress conditions with temperatures above the non-stress level;

[0040] The salt stress degree of the crop to be diagnosed is evaluated based on the changes in temperature above the no-stress level and the morphological and physiological parameters of the crop under different salt stress conditions.

[0041] Preferably, the salt-free stress baseline is the reference value of the morphological parameters and physiological parameters of the crop under salt-free stress conditions.

[0042] Preferably, the morphological parameters include: leaf area and dry matter; the physiological parameters include: water potential, relative chlorophyll content and chlorophyll fluorescence parameters.

[0043] At least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects:

[0044] The method is based on the stress above no stress temperature (DANS) calculated based on the canopy temperature, and can evaluate the salt stress degree of crops. The calculation is simple, the dependence on parameters is small, and the crops can be diagnosed non-destructively and contactlessly. The salt stress status of crops can be detected and judged rapidly and with high throughput, so as to quantitatively judge the inhibitory effect of salt stress on corn, effectively improve the corn yield and water use efficiency under salt stress, especially the best index in the whole growth period and can guide production. Stress diagnosis through DANS is helpful to quickly take regulatory measures to alleviate salt stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0046] Figure 1 A schematic diagram of a process for diagnosing crop salt stress based on canopy temperature provided by the present invention;

[0047] Figure 2 A schematic diagram of a crop salt stress diagnosis method based on canopy temperature provided by the present invention, in which an infrared thermometer monitors canopy temperature in real time;

[0048] Figure 3 A graph showing the variation pattern of CWSI under different salt stress situations in a crop salt stress diagnosis method based on canopy temperature provided by the present invention;

[0049] Figure 4A graph showing the variation pattern of CWSI under different salt stress situations in a crop salt stress diagnosis method based on canopy temperature provided by the present invention;

[0050] Figure 5 A diagram showing the variation pattern of DANS under different salt stress situations in a crop salt stress diagnosis method based on canopy temperature provided by the present invention;

[0051] Figure 6 The relationship between DANS and CWSI of corn at different growth stages under different salt stress situations in a crop salt stress diagnosis method based on canopy temperature provided by the present invention;

[0052] Figure 7 The relationship between DANS, CWSI and physiological parameters of corn at different growth stages under different salt stress situations in a crop salt stress diagnosis method based on canopy temperature provided by the present invention; DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0054] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0055] The specific process of the crop salt stress diagnosis method based on canopy temperature in this embodiment is as follows: Figure 1 As shown, including:

[0056] S101: Obtaining the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed.

[0057] Specifically, this example uses corn as the research object, and sets the environmental conditions of the crop to be no salt stress and 0.2% salt stress.

[0058] The conditions of the non-salt stress environment are specifically set as follows: no additional salt treatment is performed on the crops, and the initial salt concentration of the soil is 0.07%; the conditions of the 0.2% salt stress environment are specifically set as follows: salt is added so that the salt content of the soil within a depth of 1m in the test site is about 0.2%.

[0059] like Figure 2 As shown, an infrared thermometer (SapIP-IRT, Dynamax Co., Houston, TX, USA) was used to continuously monitor the canopy temperature of each corn plot.

[0060] The infrared thermometer probe was placed 60 cm above the corn canopy and obliquely downward to observe the canopy temperature (T s ) and the canopy temperature of the crop to be diagnosed (T ns ).

[0061] Clear and cloudless weather was selected, and the observation time was 13:00-14:00 Beijing time. Data was collected every 15 minutes and transmitted to the data terminal in real time to achieve real-time and continuous monitoring of crop canopy temperature, and obtain the canopy temperature of crops without salt stress and the canopy temperature of crops to be diagnosed.

[0062] S102: Calculating the temperature above no stress based on the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed;

[0063] Specifically, the calculation formula for the temperature above no stress is:

[0064] DANS=T s -T ns

[0065] Where DANS is the temperature above which no stress is observed, T s is the canopy temperature of the crop to be diagnosed, T ns is the canopy temperature of the unstressed crop.

[0066] S103: Evaluate the salt stress degree of the crop to be diagnosed by using the temperature above the no-stress temperature.

[0067] Specifically, if the temperature above the no-stress level is greater than 0, it indicates that the crop to be diagnosed is under salt stress, and the larger the value of the temperature above the no-stress level is, the more severe the salt stress of the crop to be diagnosed is, and vice versa; if the temperature above the no-stress level is less than or equal to 0, it indicates that the crop to be diagnosed is not under salt stress.

[0068] Specifically, a baseline without salt stress and salt stress conditions of the crop to be diagnosed were set;

[0069] Measure the morphological and physiological parameters of crops at different growth stages under salt stress conditions;

[0070] Obtain the changes in the morphological and physiological parameters of crops under different salt stress conditions with temperatures above the non-stress level;

[0071] The salt stress degree of the diagnosed crops was evaluated based on the temperature above the no-stress level.

[0072] In order to verify the beneficial effects of the method provided by the present invention, this embodiment compares the "crop water stress index" model based on canopy temperature with the method proposed by the present invention.

[0073] Specifically, the method provided by the present invention and the "crop water stress index" model based on canopy temperature were used to diagnose corn, and the soil moisture content of the plot was obtained by measuring with a neutron meter (CPN-503, Hydroprobe, InstroTek, San Francisco, CA, USA) and calibrating with the soil drying and weighing method. The morphological parameters (leaf area, dry matter) and physiological parameters (water potential, SPAD value, Fv / Fm) of the plants under different salt stress scenarios were measured in the late vegetative growth period, reproductive growth period and maturity period of corn.

[0074] like Figure 3 and Figure 4 As shown in the figure, the "crop water stress index" model (CWSI) based on canopy temperature and the method provided by the present invention are respectively used to show the changes in different salt stress environments and different irrigation conditions, indicating that the method provided by the present invention and the "crop water stress index" model based on canopy temperature can both be used for salt stress diagnosis. At the same time, Figure 5 As shown, there is a good relationship between CWSI and DANS, that is, the more severe the salt stress is, the larger the values ​​of CWSI and DANS are.

[0075] like Figure 6 and Figure 7 As shown, CWSI and DANS have a good relationship with the morphological parameters (leaf area, dry matter) and physiological parameters (water potential, SPAD value, Fv / Fm) of corn, and can quantitatively determine the inhibitory effect of salt stress on corn growth. In addition, the no water stress baseline (NWSB) established at a specific critical growth period is more accurate and effective than the NWSB established using data from the entire growth period, indicating that DANS is the best indicator for salt stress diagnosis during the entire growth period of corn.

[0076] In summary, the verification of this example shows that the method provided by the present invention is simpler, faster, easier to operate, and convenient for high-throughput monitoring compared to CWSI. It can diagnose the degree of salt stress of corn by using a temperature above the stress-free temperature based on the canopy temperature. In the field of salt stress diagnosis of crops, a new method is provided to guide the planting and production of crops.

[0077] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for diagnosing crop salt stress based on canopy temperature, characterized in that: The following steps are involved: Obtaining the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed; the crop without salt stress and the crop to be diagnosed are under the same growth environment conditions and irrigation scenario; The temperature above no stress is determined by the difference between the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed; The salt stress degree of the crop to be diagnosed is evaluated by measuring the temperature above the no-stress level.

2. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 1, characterized in that: The crops to be diagnosed include corn, rice and wheat; The growth stages of the crop to be diagnosed include the trumpet stage, tasseling stage and milky stage.

3. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 1, characterized in that: The no-salt stress environment is that no additional salt is added, and the initial soil salt concentration is 0.07%; the salt stress environment is that salt is added so that the soil salt content within a depth of 1m in the test site is 0.2%; the irrigation scenarios include: normal irrigation, mild deficit irrigation and moderate deficit irrigation.

4. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 1, characterized in that: The acquisition of the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed comprises the following steps: Place the infrared thermometer probe 60 cm above the crop canopy; Select clear and cloudless weather conditions and specify the monitoring time of the infrared thermometer to be from 13:00 to 14:00 Beijing time; During the specified monitoring time, the canopy temperature of the crop without salt stress and the canopy temperature of the crop to be diagnosed are obtained every 15 minutes.

5. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 1, characterized in that: The calculation formula for obtaining the temperature above the no-stress temperature is: IN T s -T ns Where DANS is the temperature above which no stress is observed, T s is the canopy temperature of the crop to be diagnosed, T ns is the canopy temperature of the unstressed crop.

6. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 1, characterized in that: The method of evaluating the salt stress degree of the crop to be diagnosed by a temperature above the non-stress temperature includes: When crops are under no salt stress conditions, the canopy temperature is lower than or close to the ambient temperature through effective transpiration heat dissipation; when crops are under salt stress conditions, salt inhibits the opening of the crop's stomata, reduces the transpiration rate, and limits the canopy's heat dissipation function, causing the canopy temperature to rise. According to the canopy temperature characteristics of crops under no salt stress conditions and the canopy temperature characteristics of crops under salt stress conditions, it is determined that there is a positive correlation between the temperature above no stress and the degree of salt stress suffered by crops; Based on the positive correlation, the difference between the canopy temperature of crops under non-salt stress conditions and the canopy temperature of crops under salt stress conditions can be monitored to diagnose the degree of salt stress of crops.

7. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 1, characterized in that: The method of evaluating the salt stress degree of the crop to be diagnosed by using a temperature above the no-stress temperature also includes: If the temperature above no stress is greater than 0, it means that the crop to be diagnosed has salt stress, and the larger the value of the temperature above no stress is, the more serious the salt stress of the crop to be diagnosed is, and vice versa; If the temperature above no stress is less than or equal to 0, it means that the crop to be diagnosed does not have salt stress.

8. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 1, characterized in that: The method of evaluating the salt stress degree of the crop to be diagnosed by using a temperature above the no-stress temperature also includes: Setting a baseline of no salt stress and salt stress conditions for the crop to be diagnosed; Measure the morphological and physiological parameters of crops at different growth stages under salt stress conditions; Obtain the changes in the morphological and physiological parameters of crops under different salt stress conditions with temperatures above the non-stress level; The salt stress degree of the crop to be diagnosed is evaluated based on the changes in temperature above the no-stress level and the morphological and physiological parameters of the crop under different salt stress conditions.

9. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 8, characterized in that: The salt-free stress baseline is the reference value of the morphological parameters and physiological parameters of the crop under salt-free stress conditions.

10. A method for diagnosing crop salt stress based on canopy temperature as claimed in claim 8, characterized in that: The morphological parameters include: leaf area and dry matter; The physiological parameters include: water potential, relative chlorophyll content and chlorophyll fluorescence parameters.

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