CN115308368A - Farmland crop water stress diagnosis method and device and electronic equipment - Google Patents
Farmland crop water stress diagnosis method and device and electronic equipment Download PDFInfo
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Abstract
The invention relates to the technical field of agriculture, in particular to a method and a device for diagnosing water stress of farmland crops and electronic equipment. The farmland crop water stress diagnosis method comprises the following steps: obtaining the plant transpiration amount of a plant to be detected in a farmland area; determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount; determining the ideal stomatal conductance of the plant to be detected according to the photosynthetic effective radiation, the saturated water vapor pressure difference and the air temperature in the current environment; determining the water stress coefficient of the plant to be tested according to the actual stomatal conductance and the ideal stomatal conductance; and determining whether the plant to be detected has water stress or not according to the water stress coefficient. Therefore, errors caused by measurement of a single plant are avoided, the finally obtained judgment result can more accurately represent the whole water shortage state of the plant in the farmland area, and scientific guidance is provided for farmland irrigation decisions.
Description
Technical Field
The invention relates to the technical field of agriculture, in particular to a method and a device for diagnosing water stress of farmland crops and electronic equipment.
Background
Improving the agricultural water efficiency is a core task for ensuring the agricultural water safety and the grain safety, and meanwhile, water stress is the most common stress to crops. Therefore, it is very important to scientifically judge the water requirement of crops and reasonably diagnose the water shortage state of crops. At present, the water shortage diagnosis of crops is mainly based on indexes such as soil moisture, canopy temperature, leaf water potential, air hole conductivity and the like. For example, the invention application with the application number of 202110303094.X discloses an irrigation decision system and method based on the hydraulic conductance of plants, which utilizes the water potential difference and the transpiration rate of the base end and the top end of a reference plant and a plant to be detected measured, which are measured by a water potential meter and a liquid flow meter, to obtain the water conductance index of the plant to be detected, judge the water shortage degree of the plant and adjust the current irrigation strategy. The method avoids the measurement error caused by the damage of the original method for measuring the hydraulic conductivity to the plants, and realizes the real-time acquisition of data and the real-time monitoring of the water shortage condition. For example, the invention application with the application number of 202110270346.3 discloses a method and a system for diagnosing plant water stress based on high flux stomatal conductance, which convert the measured high flux stem flow of a reference plant and a plant to be detected into transpiration rate, obtain the high flux stomatal conductance of the reference plant and the plant to be detected through other parameters such as net radiation intercepted by a canopy, meteorological factors and the like, and calculate and obtain a water stress index according to the stomatal conductance for diagnosis. Realizes long-time, high-pass and continuous monitoring, quantification and diagnosis of the plant water stress.
However, at present, water shortage diagnosis based on plant physiological state is usually performed by comparing each index of a plant to be detected with each index of a reference plant under a water-free stress state to obtain a crop water shortage diagnosis result. For example, the inventions with application numbers of 202110303094.X and 202110270346.3 require that the reference plant and the plant to be tested are observed at the same time and are in the same growing environment and the same type. However, in practical farmland application, the prior art has the following disadvantages: (1) The consistency between the reference plant and the plant to be detected is difficult to ensure, and the state without water deficit is difficult to define and judge, which will have certain influence on the diagnosis result. (2) Due to the limitation of a parameter measuring instrument, the stem flow meter can be used only when the plant stem reaches the lowest diameter of the sensor, so that the stem flow meter cannot be used for measuring the hydraulic conductivity of the plant stem at the early development stage of the stem due to the small diameter. The rapid growth stage of the stem development is just the stage of the plant with the strongest water demand, and the accurate judgment of the water stress state at the stage and the timely regulation of irrigation are very important for the growth and development of the plant. (3) At present, most of water shortage diagnosis based on plant physiological states is monitoring on a single plant, the whole water shortage state of a farmland crop is difficult to represent, and measurement errors caused by subjective plant selection exist, so that effective guidance is difficult to provide for irrigation decisions.
Therefore, the prior art has certain measurement errors in the measurement of the integral water shortage state of the farmland crops, and is difficult to provide effective guidance for irrigation decisions.
Disclosure of Invention
The invention provides a method and a device for diagnosing water stress of farmland crops and electronic equipment, which are used for solving the technical problems that certain measurement errors exist in the measurement of the integral water shortage state of the farmland crops in the prior art, and effective guidance is difficult to provide for irrigation decisions.
The invention provides a farmland crop water stress diagnosis method, which comprises the following steps:
acquiring plant transpiration of a plant to be detected in a farmland area;
determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount;
determining the ideal stomatal conductance of the plant to be detected according to the photosynthetic effective radiation, the saturated water vapor pressure difference and the air temperature in the current environment;
determining the water stress coefficient of the plant to be detected according to the actual air hole conductivity and the ideal air hole conductivity;
and determining whether the plant to be detected has water stress or not according to the water stress coefficient.
According to the farmland crop water stress diagnosis method provided by the invention, the step of determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount comprises the following steps:
acquiring radiation, soil heat flux and saturated water-vapor pressure difference of the farmland area under the current environment;
and determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount, the radiation, the soil heat flux and the saturated water-vapor pressure difference.
According to the farmland crop water stress diagnosis method provided by the invention, the step of determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount, the radiation, the soil heat flux and the saturated water-vapor pressure difference comprises the following steps:
calculating the actual stomatal conductance of the plant to be detected according to the plant transpiration amount by the following formula (1):
in the above formula (1), g s The actual porosity conductance; gamma is a humidity constant; lambda is the latent heat of vaporization of water; t is a unit of r The plant transpiration amount is; r is a Aerodynamic drag; r n Is the net radiation; g is soil heat flux; delta is the slope of the correlation curve between the saturated vapor pressure and the temperature; ρ is the air density; c p Is the constant pressure specific heat of air; VPD is the saturated water vapor pressure difference.
According to the farmland crop water stress diagnosis method provided by the invention, the step of acquiring the plant transpiration amount of a plant to be detected in a farmland area comprises the following steps:
obtaining the leaf area index of the plant to be detected, the soil water content of the surface layer of the farmland and the total evapotranspiration of the farmland;
calculating the soil surface evaporation capacity according to the leaf area index of the plant to be detected and the water content of the soil on the surface layer of the farmland through the following formula (2);
calculating plant transpiration according to the total evapotranspiration of the farmland and the soil surface evaporation by the following formula (3);
T r ＝ET-E (3)
in the above formula (2), E is the soil surface evaporation amount; ET 0 Raising the amount of the reference crop; L4I is the leaf area index of the plant to be detected; theta 10 The water content of the surface soil of the farmland; a. b and c are experience coefficients corresponding to the plant to be detected; in the above formula (3), T r The plant transpiration amount is; ET is total evapotranspiration of farmland.
According to the farmland crop water stress diagnosis method provided by the invention, the determination of the ideal stomatal conductance of the plant to be detected according to the photosynthetically active radiation, the saturated water-vapor pressure difference and the air temperature under the current environment comprises the following steps: inputting the photosynthetic effective radiation, the saturated water vapor pressure difference and the air temperature in the current environment into a preset air hole conductivity model to obtain the ideal air hole conductivity;
the stomatal conductance model adopts the following formula (4) to calculate the ideal stomatal conductance of the plant to be measured;
g s，max ＝f(PAR)·f(VPD)·f(T a ) (4)
in the above formula (4), g s，max The ideal stomatal conductance under the state of no moisture stress; PAR is photosynthetically active radiation, VPD is saturated water vapor pressure difference, T a Is the air temperature;
the above-mentioned
The above-mentioned
F (T) is a )＝k 4 +k 5 T a +k 6 T a 2 (7)
K in the above formulas (5), (6) and (7) 1 、k 2 、k 3 、k 4 、k 5 、k 6 And model parameters of the gas hole guiding degree model.
According to the farmland crop water stress diagnosis method provided by the invention, the step of determining the water stress coefficient of the plant to be detected according to the actual air hole conductance and the ideal air hole conductance comprises the following steps:
calculating a water stress coefficient by the following formula (8);
ω＝1-g s /g s，max (8)
in the above formula (8), ω is a water stress coefficient; g s The actual porosity conductance; g is a radical of formula s，max Is ideal porosity conductivity.
According to the farmland crop water stress diagnosis method provided by the invention, the step of determining whether the plant to be detected has water stress according to the water stress coefficient comprises the following steps:
if the water stress coefficient is 0, determining that the plant to be detected has no water stress; and if the water stress coefficient is larger than 0, determining that the plant to be detected has water stress, and if the water stress coefficient is larger, determining that the water stress degree of the plant to be detected is more serious.
The method for diagnosing the water stress of the farmland crops, provided by the invention, further comprises the following steps: after the actual stomatal conductance of the plant to be detected under the moisture stress condition is obtained, correcting the stomatal conductance model by adopting the actual stomatal conductance under the moisture stress condition to obtain a corrected stomatal conductance model, so that the ideal stomatal conductance calculated according to the corrected stomatal conductance model approaches to the actual stomatal conductance under the moisture stress condition;
and the corrected stomatal conductance model is used for calculating the ideal stomatal conductance of the plant to be measured in the next stage.
According to the farmland crop water stress diagnosis method provided by the invention, after the actual stomatal conductance of the plant to be detected is obtained, the stomatal conductance model is corrected by adopting the actual stomatal conductance under the condition of no water stress, and the obtained corrected stomatal conductance model comprises the following steps:
after the actual stomatal conductance of the plant to be detected is obtained, adjusting model parameters of the stomatal conductance model so that the ideal stomatal conductance calculated according to the stomatal conductance model is close to or equal to the actual stomatal conductance under the moisture-free stress condition;
and setting the model parameters of the gas hole guiding degree model as the adjusted model parameters to obtain the corrected gas hole guiding degree model.
According to the farmland crop water stress diagnosis method provided by the invention, the plant transpiration amount of a plant to be detected in a farmland area is obtained; determining the actual stomatal conductance of the plant to be detected under the moisture stress free condition according to the plant transpiration amount comprises the following steps:
and acquiring plant transpiration and meteorological elements under a clear weather condition within three days after the farmland area is irrigated, and calculating the actual stomatal conductance under the moisture-stress-free condition according to the plant transpiration and meteorological elements under the clear weather condition.
The invention also provides a farmland crop water stress diagnostic device, which comprises:
the acquisition module is used for acquiring the plant transpiration amount of a plant to be detected in a farmland area;
the first calculation module is used for determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount;
the second calculation module is used for determining the ideal stomatal conductance of the plant to be detected according to the photosynthetic effective radiation, the saturated water-vapor pressure difference and the air temperature in the current environment;
the third calculation module is used for determining the water stress coefficient of the plant to be detected according to the actual air hole conductivity and the ideal air hole conductivity;
and the determining module is used for determining whether the plant to be detected has water stress according to the water stress coefficient.
The invention also provides an electronic device, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the program to realize the method for diagnosing the water stress of the farmland crops.
The present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements a method of diagnosing moisture stress of a field crop as in any one of the above.
According to the method for diagnosing the water stress of the farmland crops, the plant transpiration amount of the plants to be detected in the farmland area is obtained; determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount; determining the ideal stomatal conductance of the plant to be detected according to the photosynthetic effective radiation, the saturated water vapor pressure difference and the air temperature in the current environment; determining the water stress coefficient of the plant to be detected according to the actual air hole conductivity and the ideal air hole conductivity; and determining whether the plant to be detected has water stress or not according to the water stress coefficient. Therefore, errors caused by measurement of a single plant are avoided, the finally obtained judgment result can more accurately represent the whole water shortage state of the plant in the farmland area, and scientific guidance is provided for farmland irrigation decisions.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a method for diagnosing water stress of a farmland crop provided by the invention;
FIG. 2 is a schematic diagram of the variation of the water stress coefficient of crops in the growth cycle provided by the present invention;
FIG. 3 is a schematic structural diagram of a device for diagnosing water stress of farm crops according to the present invention;
fig. 4 is a schematic structural diagram of an electronic device provided in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
According to the method, a farmland area is taken as a whole, the actual stomatal conductance is calculated by obtaining the plant transpiration amount of the farmland area, meanwhile, the current ideal stomatal conductance is calculated by adopting a preset stomatal conductance model, the water stress coefficient of the plant to be detected is obtained through the actual stomatal conductance and the ideal stomatal conductance, and therefore whether the plant is subjected to water stress currently or not is determined according to the water stress coefficient. The method overcomes the diagnosis error caused by measuring a single plant, and the judgment on the water shortage diagnosis of the plant is more accurate.
The solution of the invention is further explained below with reference to the drawings.
The first embodiment is as follows:
the embodiment provides a method for diagnosing water stress of farmland crops, and as shown in figure 1, the method comprises the following steps:
step 101: and acquiring the plant transpiration amount of the plant to be detected in a farmland area.
Wherein, the step 101 specifically includes:
acquiring a leaf area index and a total farmland evapotranspiration of a plant to be detected by an unmanned aerial vehicle remote sensing technology, acquiring the soil moisture content of the surface layer of a farmland by a soil moisture sensor, and acquiring meteorological elements including temperature, radiation and saturated water vapor pressure difference by a field meteorological station;
and then calculating the soil surface evaporation capacity according to the leaf area index of the plant to be detected and the water content of the soil on the surface layer of the farmland through the following formula (2):
calculating plant transpiration according to the total evapotranspiration of the farmland and the soil surface evaporation by the following formula (3);
T r ＝ET-E (3)
in the formula (2), E is the soil surface evaporation capacity and the unit is mm; ET 0 To determine the amount of crop transpiration, ET 0 Generally according to what is proposed with reference to FAO56The method is calculated, and the unit of the method is mm; LAI is leaf area index of the plant to be detected, and the unit is m 2 m -2 ；θ 10 Is the surface soil water content of farmland, and the unit is m 3 m -3 In this embodiment,. Theta. 10 The water content of the farmland soil is 10cm deep. a. b and c are empirical coefficients corresponding to the plant to be tested, taking corn in the river-crossing region as an example in the embodiment, the values of empirical parameters in the practical embodiment are a =4.8, b =0.23 and c =1.73; in the above formula (3), T r The plant transpiration amount is expressed in mm; ET is total evapotranspiration of farmland, and the unit is mm.
Step 102: and determining the actual stomatal conductance of the plant to be detected according to the plant transpiration.
In this embodiment, meteorological data is combined with a Penman-Montieth formula (a Penman formula) to obtain the stomatal conductance under an actual condition through a plant transpiration amount calculation, the radiation, the soil heat flux of a farmland area and the saturated water-vapor pressure difference under the current environment need to be obtained, and then the actual stomatal conductance of a plant to be detected is determined according to the plant transpiration amount, the radiation, the soil heat flux and the saturated water-vapor pressure difference. Specifically, the actual stomatal conductance of the plant to be detected is calculated according to the plant transpiration through the following formula (1):
in the above formula (1), g s The actual porosity is expressed in ms -1 (ii) a Gamma is the humidity constant in kPa C -1 (ii) a Lambda is the latent heat of vaporization of water, in J kg -1 In this embodiment, λ is 2.45 × 10 6 。T r The plant transpiration amount is expressed in mm; r is a Is aerodynamic drag in units of sm -1 ；R n For net radiation, it has the unit W m -2 (ii) a G is the soil heat flux, which is expressed in Wm -2 (ii) a Delta is the slope of the curve relating saturated water vapor pressure to temperature in kPa DEG C -1 (ii) a ρ is the air density in kg m -3 ；C p Is the specific heat at constant pressure of air, and has a unit of J kg -1 ℃ -1 (ii) a VPD is the saturated water vapor pressure difference. In this example, γ, λ, r a 、R n 、G、ρ、C p The VPD can be obtained by responding to sensor monitoring or by a database of a weather station, and the calculation of the relevant parameters in the above formula (1) can be referred to the FAO56 catalog.
Step 103: and determining the ideal stomatal conductance of the plant to be detected according to the photosynthetic effective radiation, the saturated water vapor pressure difference and the air temperature in the current environment.
Specifically, in step 103, the photosynthetically active radiation, the saturated water vapor pressure difference, and the air temperature in the current environment are input into a preset stomatal conductance model, so as to obtain an ideal stomatal conductance.
In the embodiment, the ideal state stomatal conductance under the condition of no moisture stress is obtained by using a Jarvis multifactor multiplied by the closed stomatal conductance model according to meteorological factors, namely, the preset stomatal conductance model is the Jarvis multifactor multiplied by the closed stomatal conductance model, and the concrete expression form of the stomatal conductance model is the following formula (4).
Calculating the ideal stomatal conductance of the plant to be measured by adopting the following formula (4);
g s，max ＝f(PAR)·f(VPD)·f(T a ) (4)
in the above formula (4), g s，max The ideal stomatal conductance under the state of no moisture stress is expressed in the unit of ms -1 (ii) a PAR is photosynthetically active radiation, which has the unit of μmol m -2 s -1 F (PAR) is a response formula of porosity conductance to PAR; VPD is saturated steam pressure difference with the unit of kPa, and f (VPD) is a response formula of porosity conductivity to VPD; t is a unit of a Is the air temperature in degrees Celsius, f (T) a ) Is the conductance of the air hole to T a The response formula of (2). Photosynthetic effective radiation, saturated vapor pressure difference and air temperature are respectively obtained, then corresponding response formulas are calculated, and finally the ideal stomatal conductance is calculated through a formula (4).
Step 104: and determining the water stress coefficient of the plant to be detected according to the actual air hole conductivity and the ideal air hole conductivity.
Specifically, in this embodiment, determining the water stress coefficient of the plant to be tested according to the actual stomatal conductance and the ideal stomatal conductance includes:
calculating a water stress coefficient by the following formula (8);
ω＝1-g s /g s，max (8)
in the above formula (8), ω is a water stress coefficient; g s The actual porosity is expressed in ms -1 ；g s，max The ideal porosity conductance is expressed in ms -1 。
Step 105: and determining whether the plant to be detected has water stress or not according to the water stress coefficient.
In this embodiment, the step 105 specifically includes: if the water stress coefficient is 0, determining that the plant to be detected has no water stress; and if the water stress coefficient is larger than 0, determining that the plant to be detected has water stress, and if the water stress coefficient is larger, determining that the water stress degree of the plant to be detected is more serious.
In order to enable the ideal stomatal conductance obtained through calculation to be more accurate, plant transpiration and meteorological elements under a clear weather condition within three days after irrigation of the farmland area are obtained, and the actual stomatal conductance is calculated according to the plant transpiration and meteorological elements under the clear weather condition to serve as the stomatal conductance under the moisture stress-free condition. For example, if there is a sunny day or more after the irrigation, the average value of the actual porosity per day in the sunny day is calculated, and if there is only one sunny day, the actual porosity in the day is used as the standard.
Further, in this embodiment, after obtaining the actual stomatal conductance of the plant to be tested under the moisture-stress-free condition, the stomatal conductance model is further modified by using the actual stomatal conductance under the moisture-stress-free condition to obtain a modified stomatal conductance model, so that the ideal stomatal conductance calculated according to the modified stomatal conductance model is close to the actual stomatal conductance under the moisture-stress-free condition. The corrected stomatal conductance model is used for calculating the ideal stomatal conductance of the plant to be detected in the next stage, so that the calculated ideal stomatal conductance of the plant to be detected in the next stage is closer to the stomatal conductance under no moisture stress, and the calculation of the moisture stress coefficient is more accurate.
Specifically, in this embodiment, when the corn in the river-crossing region is taken as an example, the corresponding response formulas in the formula (4) are respectively:
f(T a )＝k 4 +k 5 T a +k 6 T a 2 (7)
k in the above formulas (5), (6) and (7) 1 、k 2 、k 3 、k 4 、k 5 、k 6 Model parameters of the porosity conductance model.
Further, in this embodiment, after the moisture stress on the plant to be tested is determined at each stage, the stomatal conductance model is modified, specifically, the modification is performed in the following manner: after the actual stomatal conductance of the plant to be detected is obtained, adjusting model parameters of the stomatal conductance model, so that the ideal stomatal conductance calculated according to the stomatal conductance model is close to or equal to the actual stomatal conductance under the condition of no moisture stress; and setting the model parameters of the gas hole guiding degree model as the adjusted model parameters to obtain the corrected gas hole guiding degree model. For example, in this embodiment, at the current stage, the model parameters corresponding to the gas hole conductance model are: k is a radical of formula 1 ＝1450、k 2 ＝0.01、k 3 ＝1.57、k 4 ＝103、k 5 ＝-6.1、k 6 =0.115. At this time, the ideal stomatal conductance at day 6 and 20, which was calculated by the above equation (4) under clear weather conditions after the last irrigation, was 3.28 ms -1 Under the same weather condition, the stomatal conductance in clear weather under the actual moisture stress-free state after water irrigation calculated by adopting the formula (1) is 2.34 ms -1 Then adopt asThe correction method corrects the model parameters of the porosity conductance model, and the corrected model parameters obtained by the method of the embodiment are respectively a number k 1 ＝1370、k 2 ＝0.03、k 3 ＝2.18、k 4 ＝96、k 5 ＝-5.4、k 6 =0.25, and the ideal pore conductance calculated using the corrected pore conductance model is 2.41 ms -1 It can be seen that the ideal stomatal conductance calculated by the corrected stomatal conductance model is basically close to the actual stomatal conductance without moisture stress calculated by actually collecting various data. And then, in the next measurement stage, the corrected stomatal conductance model is adopted to calculate the ideal stomatal conductance of the plant to be measured, so that the ideal stomatal conductance calculated by the model is more accurate, and the prediction of whether the plant to be measured has water stress is more accurate.
In this embodiment, the corn under irrigation condition is taken as an example, and the water stress coefficients corresponding to the corn in multiple stages are obtained by using the method for calculating the water stress coefficients of this embodiment. For example, referring to fig. 2, fig. 2 shows the water stress coefficients of corn at various stages of a part of the growing cycle, the broken line in fig. 2 is the change of the water stress index of the irrigated corn during the growing cycle, and P + I in fig. 2 represents rainfall and irrigation, i.e., the circular lines in fig. 2 represent the amount of rainfall and irrigation at different periods. As can be seen from FIG. 2, the corn has a greater demand for water during the critical growth period (the jointing stage), and the water stress coefficient before the corn is irrigated is higher and reaches 0.79. Then along with each irrigation, the water stress degree of the corn is relieved, the water stress coefficient is reduced to about 0.28, and the corn is continuously fluctuated along with meteorological conditions and irrigation conditions. The irrigation amount is about 60 percent of that of full irrigation in the grouting maturation period, and the water stress coefficient gradually rises and is about 0.36 on average. According to the crop water stress coefficient, dynamic information of farmland water conditions can be obtained, and further help and guidance are provided for accurate irrigation decisions.
It should be noted that, in this embodiment, the above-mentioned partial physical parameter information may be directly obtained through monitoring at a local weather station, or obtained by using a corresponding sensor and an unmanned aerial vehicle remote sensing technology, which is all realizable by those skilled in the art, and is not described in detail in this embodiment.
Compared with the prior art, the method for diagnosing the water stress of the farmland crops has the following advantages:
first, the method of this embodiment requires less monitoring data and does not require the use of a stem flow meter, and thus does not cause destructive damage to the plant. The embodiment utilizes unmanned aerial vehicle remote sensing and to meteorological factor and soil moisture's measurement, can calculate the gas pocket conductance on farmland canopy, realizes acquireing the real-time pore state in farmland.
Secondly, the present embodiment calculates the conductance of the air holes by using the total evapotranspiration of the farmland, and obtains the total water shortage state of the farmland by using the air hole state. The diagnosis error caused by measurement of a single plant is reduced, so that the calculated water stress coefficient can accurately represent the current water shortage state of the farmland, and the accurate guiding effect on scientific irrigation is achieved.
Thirdly, in the embodiment, the gas pore conductivity model is dynamically corrected by adopting the actual gas pore conductivity at each measurement stage, so that the ideal gas pore conductivity calculated by the gas pore conductivity model is closer to the gas pore conductivity under the actual moisture stress-free state, and the final water shortage assessment is more accurate. In addition, in the present embodiment, the stomatal conductance in clear weather after each time of sufficient irrigation is used as the actual stomatal conductance in the moisture deficit free state in this stage, which is closer to the actual situation, and the determination of the water deficit diagnosis is more accurate.
Example two:
the present embodiment provides a device for diagnosing water stress of farm crops, as shown in fig. 3, the device includes: the system comprises an acquisition module 301, a first calculation module 302, a second calculation module 303, a third calculation module 304 and a determination module 305.
The obtaining module 301 is used for obtaining plant transpiration of a plant to be detected in a farmland area; the first calculation module 302 is used for determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount; the second calculation module 303 is configured to determine an ideal stomatal conductance of the plant to be detected according to the photosynthetically active radiation, the saturated water-vapor pressure difference, and the air temperature in the current environment; the third calculation module 304 is used for determining the water stress coefficient of the plant to be measured according to the actual stomatal conductance and the ideal stomatal conductance; the determining module 305 is configured to determine whether the plant to be tested has water stress according to the water stress coefficient, so as to provide scientific guidance for plant irrigation.
In another embodiment, the diagnostic apparatus further includes an output module 306, and the output module 306 is configured to output the determination result of the determination module 305. For example, the output module 306 employs a display screen for displaying the determination result, which generally includes the water stress coefficient and the result of whether the plant has water stress, for example, the output determination result is: the water stress coefficient of the corn in the current farmland area is 0.79, and the corn has water stress, so that timely irrigation is recommended.
Specifically, the implementation process of each module in this embodiment corresponds to each implementation step in the first embodiment one to one, and is not described here again.
Example three:
fig. 4 illustrates a physical structure diagram of an electronic device, which may include, as shown in fig. 4: a processor (processor) 401, a communication Interface (communication Interface) 402, a memory (memory) 403 and a communication bus 404, wherein the processor 401, the communication Interface 402 and the memory 403 complete communication with each other through the communication bus 404. The processor 401 may call logic instructions in the memory 403 to execute the method for diagnosing water stress of farm crops according to the first embodiment.
In addition, the logic instructions in the memory 403 may be implemented in the form of software functional units and stored in a computer readable storage medium when the software functional units are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, the present invention also provides a non-transitory computer readable storage medium, on which a computer program is stored, the computer program being executed by a processor to implement the method for diagnosing water stress of farm crops provided by the above methods.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. Based on the understanding, the above technical solutions substantially or otherwise contributing to the prior art may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the various embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (13)
1. A method for diagnosing water stress of farmland crops is characterized by comprising the following steps:
acquiring plant transpiration of a plant to be detected in a farmland area;
determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount;
determining the ideal stomatal conductance of the plant to be detected according to the photosynthetic effective radiation, the saturated water vapor pressure difference and the air temperature in the current environment;
determining the water stress coefficient of the plant to be detected according to the actual air hole conductivity and the ideal air hole conductivity;
and determining whether the plant to be detected has water stress or not according to the water stress coefficient.
2. The method for diagnosing water stress of farmland crops according to claim 1, wherein the determination of the actual stomatal conductance of the plant to be tested according to the plant transpiration amount comprises:
acquiring radiation, soil heat flux and saturated water-vapor pressure difference of the farmland area in the current environment;
and determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount, the radiation, the soil heat flux and the saturated water vapor pressure difference.
3. The method for diagnosing water stress of farmland crops as claimed in claim 2, wherein the step of determining the actual stomatal conductance of the plant to be tested according to the plant transpiration amount, the radiation, the soil heat flux and the saturated water vapor pressure difference comprises the following steps:
calculating the actual stomatal conductance of the plant to be detected according to the plant transpiration amount by the following formula (1):
in the above formula (1), g s The actual porosity conductance; gamma is a humidity constant; lambda is the latent heat of vaporization of water; t is a unit of r The plant transpiration amount is; r is a Aerodynamic drag; r n Is the net radiation; g is soil heat flux; delta is the slope of the correlation curve between the saturated vapor pressure and the temperature; ρ is the air density; c p Is the constant pressure specific heat of air; VPD is the saturated water vapor pressure difference.
4. The method for diagnosing water stress of farmland crops according to claim 1, wherein the step of obtaining the plant transpiration of the plant to be tested in a farmland area comprises the steps of:
obtaining the leaf area index of the plant to be detected, the soil water content of the surface layer of the farmland and the total evapotranspiration of the farmland;
calculating the soil surface evaporation capacity according to the leaf area index of the plant to be detected and the water content of the soil on the surface layer of the farmland through the following formula (2);
calculating plant transpiration according to the total evapotranspiration of the farmland and the soil surface evaporation by the following formula (3);
T r ＝ET-E (3)
in the formula (2), E is the soil surface evaporation capacity; ET 0 Raising the amount of the reference crop; LAI is the leaf area index of the plant to be detected; theta 10 The water content of the surface soil of the farmland; a. b and c are experience coefficients corresponding to the plant to be detected; in the above formula (3), T r The plant transpiration amount is; ET is total evapotranspiration of farmland.
5. The method for diagnosing water stress of farmland crops as claimed in claim 1, wherein the determining of the ideal stomatal conductance of the plant to be tested according to the photosynthetically active radiation, the saturated water vapor pressure difference and the air temperature under the current environment comprises: inputting the photosynthetic effective radiation, the saturated water vapor pressure difference and the air temperature in the current environment into a preset air hole conductivity model to obtain the ideal air hole conductivity;
the stomatal conductance model adopts the following formula (4) to calculate the ideal stomatal conductance of the plant to be measured;
g s,max ＝f(PAR)·f(VPD)·f(T a ) (4)
in the above formula (4), g s,max The ideal stomatal conductance under the state of no moisture stress; PAR is photosynthetically active radiation, VPD is the saturated water-vapor pressure difference, T a Is the air temperature;
the above-mentioned
The above-mentioned
F (T) a )＝k 4 +k 5 T a +k 6 T a 2 (7)
K in the above formulas (5), (6) and (7) 1 、k 2 、k 3 、k 4 、k 5 、k 6 And the model parameters are model parameters of the gas hole conductivity model.
6. The method for diagnosing water stress of farmland crops according to claim 1, wherein the determining of the water stress coefficient of the plant to be tested according to the actual stomatal conductance and the ideal stomatal conductance comprises:
calculating a water stress coefficient by the following formula (8);
ω＝1-g s /g s,max (8)
in the above formula (8), ω is a water stress coefficient; g s The actual porosity conductance; g is a radical of formula s,max Is an ideal stomatal conductance.
7. The method for diagnosing water stress of farmland crops according to claim 6, wherein said determining whether water stress exists in the plant to be tested according to the water stress coefficient comprises:
if the water stress coefficient is 0, determining that the plant to be detected does not have water stress; and if the water stress coefficient is larger than 0, determining that the plant to be detected has water stress, and if the water stress coefficient is larger, determining that the water stress degree of the plant to be detected is more serious.
8. The method of diagnosing water stress in a field crop of claim 5, further comprising: after the actual stomatal conductance of the plant to be detected is obtained, correcting the stomatal conductance model by adopting the actual stomatal conductance under the moisture-free stress condition to obtain a corrected stomatal conductance model, so that the ideal stomatal conductance calculated according to the corrected stomatal conductance model is close to the actual stomatal conductance under the moisture-free stress condition;
and the corrected stomatal conductance model is used for calculating the ideal stomatal conductance of the plant to be measured in the next stage.
9. The method for diagnosing moisture stress of farmland crops according to claim 8, wherein after obtaining the actual stomatal conductance under the moisture stress free condition of the plant to be tested, the method for correcting the stomatal conductance model by using the actual stomatal conductance under the moisture stress free condition comprises:
after the actual stomatal conductance of the plant to be detected under the moisture-stress-free condition is obtained, adjusting model parameters of the stomatal conductance model, so that the ideal stomatal conductance calculated according to the stomatal conductance model is close to or equal to the actual stomatal conductance under the moisture-stress-free condition;
and setting the model parameters of the gas hole conductivity model as the adjusted model parameters to obtain the corrected gas hole conductivity model.
10. The method for diagnosing water stress of farmland crops according to claim 9, wherein the plant transpiration of plants to be tested in a farmland area is obtained; determining the actual stomatal conductance of the plant to be detected under the condition of no moisture stress according to the plant transpiration amount, wherein the actual stomatal conductance comprises the following steps:
and acquiring plant transpiration and meteorological elements under a clear weather condition within three days after the farmland area is irrigated, and calculating the actual stomatal conductance under the moisture-free stress condition according to the plant transpiration and meteorological elements under the clear weather condition.
11. A diagnostic device for water stress of farmland crops is characterized by comprising:
the acquisition module is used for acquiring the plant transpiration amount of a plant to be detected in a farmland area;
the first calculation module is used for determining the actual stomatal conductance of the plant to be detected according to the plant transpiration amount;
the second calculation module is used for determining the ideal stomatal conductance of the plant to be detected according to the photosynthetic effective radiation, the saturated water-vapor pressure difference and the air temperature in the current environment;
the third calculation module is used for determining the water stress coefficient of the plant to be detected according to the actual air hole conductivity and the ideal air hole conductivity;
and the determining module is used for determining whether the plant to be detected has water stress according to the water stress coefficient.
12. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the program implements the method of diagnosing moisture stress in a field crop as claimed in any one of claims 1 to 10.
13. A non-transitory computer readable storage medium having a computer program stored thereon, wherein the computer program when executed by a processor implements the method of diagnosing moisture stress in a field crop of any one of claims 1 to 10.
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