CN107392503B - Method for evaluating high-temperature heat damage risk of corn - Google Patents

Abstract

The invention provides a method for evaluating the risk of high temperature heat damage to corn. The method includes: preprocessing MODIS LST remote sensing image data to obtain the surface temperature; according to the surface temperature, a moving window algorithm is used to calculate a high temperature abnormality index, and according to the high temperature abnormality The index obtains the abnormal temperature area; according to the surface temperature and the distribution of corn flowering period, obtains the heat damage risk days and heat damage risk accumulation temperature in the corn flowering period in the temperature abnormal area; and calculates the accumulated temperature index. The present invention is based on MODIS LST remote sensing image data. Compared with the point source data of meteorological stations used in previous research, the remote sensing image data can more accurately reflect the temporal and spatial distribution of high temperature, and provide support for agricultural high temperature risk assessment; Efficiently and accurately assess the risk level of high-temperature heat damage in the flowering stage of corn, provide support for the prevention of high-temperature heat damage in corn, and improve the efficiency and accuracy of high-temperature heat damage prevention in corn.

Description

A method for assessing the risk of high temperature heat damage to corn

technical field

The invention relates to the field of agro-meteorological disaster early warning, in particular to a method for evaluating the risk of high temperature heat damage to corn.

Background technique

In the process of maize production, temperature is an important meteorological factor. Excessive temperature will seriously affect the growth and development of maize. With the continuous warming of the climate in recent years, the frequency of abnormally high temperature weather in corn production areas in my country has become more and more frequent, which has brought serious harm to corn production.

High temperature affects maize photosynthesis. Under high temperature conditions, the activity of photosynthetic proteases is reduced, the chloroplast structure is destroyed, causing stomata to close, thereby weakening photosynthesis; on the other hand, under high temperature conditions, respiration is enhanced, consumption increases, and dry matter accumulation decreases. The longer the time of high temperature stress, the more serious the damage to the plant and the more difficult it is to recover. High temperature forces accelerated various physiological and biochemical reactions in the maize growth process and shortened each growth stage. If the ear differentiation time is shortened, the number of ear florets differentiation decreases, and the ear becomes smaller. In the late growth stage, high temperature makes corn plants die prematurely, or ends the growth process prematurely and enters the mature stage. The grain filling time is shortened, the dry matter accumulation is reduced, and the 1000-grain weight, test weight, yield and quality are reduced.

Maize tassel meiosis and pollination stage are sensitive to temperature. If dry weather is encountered during the flowering period of corn, abortive pollen is often formed, or the pollen dies rapidly, resulting in failure of normal fertilization and fruiting. In the process of maize tassel development to flowering and powdering, the high temperature cannot restore part of the sterility process of some maize varieties, resulting in a substantial decrease in the seed setting rate of maize, which has a huge impact on production, and in severe cases will lead to production failure. Studies have shown that the longer the duration of high temperature stress, the greater the risk of plant damage and the more difficult it is to recover.

High temperature has a very important influence on the growth of corn, and the critical value of high temperature varies with the growth period of corn. Some stages of the corn growth period, such as the flowering period of corn, are sensitive to heat damage. If they suffer from high temperature heat damage, the growth and development of corn will be seriously affected, and the phenomenon of corn empty stalks, bald tips, lack of grains, and lack of rows will lead to the production of corn. And the decline in quality has seriously affected farmers' harvested yield and economic income.

Therefore, how to propose a simple and efficient assessment method for high temperature risk of corn has become an urgent problem to be solved.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned defects of the prior art, the present invention provides a method for evaluating the risk of high temperature heat damage to corn.

The invention provides a method for evaluating the risk of high temperature heat damage to corn, comprising:

Step 1, according to the surface temperature obtained by preprocessing the MODIS LST remote sensing image data, through the moving window algorithm, calculate the high temperature anomaly index, and obtain the temperature anomaly area according to the high temperature anomaly index;

Step 2, according to the surface temperature and the distribution of the corn blooming period, obtain the heat damage risk days and the heat damage risk accumulated temperature in the corn blooming stage in the abnormal temperature area; according to the heat damage risk days and the heat damage risk accumulated temperature, calculate Accumulated temperature index.

Step 3, with reference to the preset corn high temperature heat damage classification standard, obtain the high temperature heat damage risk level in the corn florescence stage in the area with abnormal temperature according to the heat damage risk days and the accumulated temperature index.

Wherein, in the step 1, the preprocessing process of the MODIS LST remote sensing image data includes:

Convert remote sensing image data coordinates to WGS-84 coordinate system, and convert pixel radiant brightness temperature to pixel surface temperature.

Wherein, in the step 1, the high temperature anomaly index is:

The difference between the surface temperature value of the pixel in the MODIS LST remote sensing image data center and the average surface temperature of the pixel.

Wherein, in the step 1, the calculation of the high temperature anomaly index by the moving window algorithm includes:

Set multiple window scales, count the average surface temperature of pixels under different window scales, and obtain the surface temperature value of the pixel in the center of the window;

Calculate the difference between the surface temperature value of the pixel in the center of the window and the average surface temperature of the pixel, where the difference is a high temperature anomaly index.

Wherein, in the step 1, the obtaining of the abnormal temperature area according to the high temperature abnormality index includes:

The area corresponding to the pixel with a continuously large high temperature anomaly index at the flowering stage of corn was selected as the temperature anomaly area.

Wherein, in the step 2, the obtaining the heat damage risk days and the heat damage risk accumulated temperature in the corn florescence stage includes:

In the area with abnormal temperature, in the corn flowering stage, the number of days when the surface temperature is greater than or equal to the preset high temperature threshold is defined as the number of days at risk of heat damage;

The heat damage risk accumulated temperature is the temperature accumulation value in the heat damage risk days, and the calculation formula is:

In the formula, Ts is the value of the accumulated temperature of heat damage risk; n is the number of heat damage risk days; t _i is the temperature value of the ith day of heat damage risk.

Wherein, the accumulated temperature index is the product of heat damage risk days and heat damage risk accumulated temperature, and the calculation formula is:

IN _t =T _s ·n

In the formula, IN _t is the value of the accumulated temperature index; Ts is the value of the accumulated temperature at risk of heat damage; n is the number of days at risk of heat damage.

Wherein, the preset high temperature threshold is 32-35°C.

Wherein, in the step 2, the distribution of the corn flowering period is obtained by performing interpolation processing using a spatial interpolation tool of spatial analysis.

Wherein, in the step 3, the preset corn high temperature heat damage classification standard includes:

Taking the accumulated temperature index and heat damage risk days at the flowering stage of corn as the evaluation indicators of high temperature heat damage risk of corn, through experiments and literature reading, the risk level of high temperature heat damage to corn was divided into grades one to four according to the severity from high to low.

The method for assessing the risk of high temperature heat damage to corn provided by the present invention is based on MODIS LST remote sensing image data, and uses a moving window to calculate the difference between the mean surface temperature of the center pixel of the window and the surrounding pixel, which is defined as a high temperature anomaly index. According to the high temperature abnormality index, the temperature abnormality area in the Huanghuaihai summer corn growing area was extracted, and the accumulated temperature index and heat damage risk days at the corn flowering stage were used as the evaluation indicators of high temperature heat damage risk of corn, and the high temperature heat damage risk level was divided into four grades. In the abnormal temperature area, the risk level of high temperature heat damage in the flowering stage of corn. The present invention is based on MODIS LST remote sensing image data. Compared with the point source data of meteorological stations used in previous research, the technical advantage of remote sensing image data lies in that it can more accurately reflect the temporal and spatial distribution of high temperature, and more accurately discover large-scale The high temperature abnormal area that occurs in the area provides support for agricultural high temperature risk assessment; the invention efficiently and accurately evaluates the high temperature heat damage risk level in the flowering stage of corn in the abnormal temperature area, provides support for the prevention of high temperature heat damage to corn, and improves the prevention of high temperature heat damage to corn. efficiency and accuracy. Avoid losses caused by high temperature disasters.

Description of drawings

1 is a schematic flowchart of an assessment method for high temperature heat damage risk of corn provided according to an embodiment of the present invention;

Fig. 2 is MODIS LST inversion surface temperature data provided according to an embodiment of the present invention;

3 is a T-Tave distribution diagram of high temperature anomaly index at different scales on July 1, 2012 provided according to an embodiment of the present invention;

FIG. 4 is a distribution diagram of the tasseling period of Huanghuaihai summer corn provided according to an embodiment of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are the Some, but not all, embodiments are disclosed. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Fig. 1 is the schematic flow chart of the assessment method of corn high temperature heat damage risk provided according to the embodiment of the present invention, as shown in Fig. 1, the method comprises:

Step S1, according to the surface temperature obtained by preprocessing the MODIS LST remote sensing image data, through the moving window algorithm, calculate the high temperature abnormality index, and obtain the temperature abnormality area according to the high temperature abnormality index; Step S2, according to the surface temperature and corn flowering period distribution If the temperature is abnormal, obtain the heat damage risk days and heat damage risk accumulated temperature in the corn florescence stage in the temperature abnormal area; calculate the accumulated temperature index according to the heat damage risk days and the heat damage risk accumulated temperature. In step S3, referring to the preset corn high temperature heat damage classification standard, obtain the high temperature heat damage risk level in the corn florescence stage in the area with abnormal temperature according to the heat damage risk days and the accumulated temperature index.

The method for evaluating the risk of high temperature heat damage to corn provided by the embodiment of the present invention is based on MODISLST remote sensing image data and uses a moving window to calculate the difference between the mean surface temperature of the center pixel of the window and the surrounding pixel, which is defined as the high temperature abnormality index. According to the high temperature abnormality index, the temperature abnormality area in the Huanghuaihai summer corn growing area was extracted, and the accumulated temperature index and heat damage risk days at the corn flowering stage were used as the evaluation indicators of high temperature heat damage risk of corn, and the high temperature heat damage risk level was divided into four grades. In the abnormal temperature area, the risk level of high temperature heat damage in the flowering stage of corn. The embodiment of the present invention is based on MODIS LST remote sensing image data. Compared with the point source data of meteorological stations used in previous research, the technical advantage of remote sensing image data is that it can more accurately reflect the temporal and spatial distribution of high temperature, and more accurately find The abnormal high temperature area that occurs in a large range provides support for agricultural high temperature risk assessment; the embodiment of the present invention efficiently and accurately evaluates the high temperature heat damage risk level in the flowering stage of corn in the abnormal temperature area, provides support for the prevention of high temperature heat damage of corn, and improves corn Efficiency and accuracy of high temperature heat damage prevention. Avoid losses caused by high temperature disasters.

Wherein, in step S1, according to the surface temperature obtained by preprocessing the MODIS LST remote sensing image data, a moving window algorithm is used to calculate the high temperature anomaly index, and the temperature anomaly area is obtained according to the high temperature anomaly index.

MODIS (moderate-resolution imaging spectroradiometer) is called moderate-resolution imaging spectroradiometer. LST (land surface temperature), the product serial number in NASA's MODIS product is MOD11A2.

MODIS is an important sensor mounted on the terra and aqua satellites. It is the only on-board instrument on the satellite that broadcasts real-time observation data directly to the world through the X-band, and can receive the data for free and use it for free. Many countries and regions around the world are receiving and using MODIS data. MODIS multi-band data can simultaneously provide reflections of land surface conditions, cloud boundaries, cloud properties, ocean color, phytoplankton, biogeography, chemistry, atmospheric water vapor, aerosols, surface temperature, cloud top temperature, atmospheric temperature, ozone and cloud top height and other characteristics information. Multi-band data can simultaneously provide information reflecting features such as land, cloud boundaries, cloud properties, ocean color, phytoplankton, biogeography, chemistry, atmospheric water vapor, surface temperature, cloud top temperature, atmospheric temperature, ozone, and cloud top height. Long-term global observations of the land surface, biosphere, solid Earth, atmosphere and ocean.

The preprocessing process of remote sensing image data of MODIS LST includes converting the coordinates of MODIS LST remote sensing image data to WGS-84 coordinate system, and converting pixel radiant brightness temperature to pixel surface temperature. Obtain a map of the inner surface temperature distribution. The WGS-84 coordinate system is an internationally adopted geocentric coordinate system. The origin of the coordinates is the earth's center of mass, and the Z-axis of the geocentric space Cartesian coordinate system points to the BIH (International Time Service Agency) 1984.O definition of the protocol Earth's pole (CTP) direction, and the X-axis points to the zero meridian plane of BIH1984.0 and the CTP equator The intersection of Y axis and Z axis and X axis are perpendicular to form a right-handed coordinate system, which is called the 1984 World Geodetic Coordinate System.

In this embodiment, the remote sensing image data of MODIS LST in the Huanghuaihai region from July 1, 2012 to August 31 is obtained, and preprocessing is performed to obtain each of the data from July 1 to August 31, 2012. The daily MODIS LST inversion map of surface temperature in the Huanghuaihai region is shown in Figure 2. FIG. 2 is a surface temperature distribution diagram of MODIS LST inversion provided according to an embodiment of the present invention.

Further, the surface temperature obtained after preprocessing of MODIS LST remote sensing data. The moving window algorithm is used, multiple window scales are set, the average surface temperature of pixels under different window scales is counted, and the surface temperature value of the pixel in the center of the window is obtained. Calculate the difference between the surface temperature value of the central pixel and the average surface temperature of the pixel, where the difference is a high temperature anomaly index (T-Tave).

FIG. 3 is a distribution diagram of the high temperature anomaly index T-Tave at different scales on July 1, 2012 according to an embodiment of the present invention, wherein FIG. 3(a) is the high temperature anomaly index T-Tave when the scale is 3×3 Distribution map; Figure 3(b) is the T-Tave distribution map of the high temperature anomaly index when the scale is 10 × 10; Figure 3(c) is the T-Tave distribution map of the high temperature anomaly index when the scale is 50 × 50. The area corresponding to the pixel with a continuously large high temperature anomaly index is selected as the temperature anomaly area, and the subsequent evaluation of the temperature anomaly area is carried out.

Among them, a pixel is the smallest unit that composes a digitized image. In remote sensing data acquisition, such as scanning imaging, it is the smallest unit for the sensor to scan and sample the ground scene; in digital image processing, it is the sampling point when scanning and digitizing analog images. When the resolution is 1 kilometer, one pixel represents the area of 1 kilometer × 1 kilometer on the ground, that is, 1 square kilometer; when the resolution is 30 meters, one pixel represents the area of 30 meters × 30 meters on the ground ; When the resolution is 1 meter, that is, one pixel on the image is equivalent to an area of 1 meter x 1 meter on the ground, or 1 square meter.

Wherein, in step S2, according to the surface temperature and the distribution of corn florescence, the heat damage risk days and the heat damage risk accumulated temperature in the corn florescence stage are obtained; according to the heat damage risk days and the heat damage risk accumulated temperature, the accumulated temperature index is calculated.

The present embodiment selects the Huang-Huai-Hai region as, according to the maize growth period data in the Huang-Huai-Hai region in Table 1, uses the spatial interpolation tool of spatial analysis to carry out interpolation processing, obtains the distribution map of corn tasseling period, as shown in Figure 4, Figure 4 is based on The distribution map of the tasseling period of Huanghuaihai summer corn provided in the embodiment of the present invention.

Table 1 Some examples of maize growth period data in Huanghuaihai region

Further, obtain the heat damage risk days and heat damage risk accumulated temperature in the flowering stage of corn, according to the MODIS LST surface temperature data in the Huanghuaihai region from July 1st to August 31st, 2012, to calculate the total temperature of the corn flowering stage. Heat damage risk days, calculate heat damage risk accumulated temperature. And according to the heat damage risk days and the heat damage risk accumulated temperature, the accumulated temperature index of the abnormal temperature area is calculated.

Wherein, in step S3, with reference to the preset corn high temperature heat damage classification standard, obtain the high temperature heat damage risk level in the corn florescence stage in the area with abnormal temperature according to the heat damage risk days and the accumulated temperature index.

Specifically, the accumulated temperature index and the number of heat damage risk days in the corn florescence stage are used as the evaluation indicators of the high temperature heat damage risk of corn, and the preset high temperature heat damage classification standard is obtained through experiments and literature reading. Table 2 is the high temperature heat damage provided by the embodiment of the present invention. Heat Hazard Risk Grading Criteria. The risk level of high temperature heat damage of corn is divided into one to four levels according to the severity from high to low, which are represented by four colors of red, orange, yellow and blue.

Table 2 Comparison of accumulated temperature index and high temperature duration with high temperature heat damage risk level

Further, according to the accumulated temperature index and heat damage risk days in the temperature anomaly area obtained by calculation, it is matched with the high temperature heat damage risk classification standard in Table 2. Obtain the risk level of high temperature heat damage during the flowering stage of corn in the area with abnormal temperature.

In the corn high temperature risk assessment method provided by the embodiment of the present invention, the accumulated temperature index and the heat damage risk days in the corn florescence stage are used as the evaluation indexes of the corn high temperature heat damage risk, and the corn high temperature heat damage risk level is divided into four levels, and the abnormal temperature is obtained. In the region, the risk level of high temperature and heat damage during the flowering stage of corn. Provide support for the prevention of high temperature and heat damage in corn, and improve the efficiency and accuracy of high temperature and heat damage prevention in corn. Avoid losses caused by high temperature disasters.

On the basis of the above embodiment, obtaining the abnormal temperature area according to the high temperature abnormality index includes:

The area corresponding to the pixel with a continuously large high temperature anomaly index at the flowering stage of corn was selected as the temperature anomaly area.

Specifically, according to the remote sensing image data of MODISLST in the Huanghuaihai region obtained from July 1, 2012 to August 31, 2012, calculate the high temperature anomaly index value every day in the corn flowering stage, and filter the high temperature anomaly index to be larger, and In the flowering stage of corn, there are more pixels with higher high temperature anomaly index, and the corresponding area of this pixel is the temperature anomaly area.

On the basis of each of the above-mentioned embodiments, according to the surface temperature and the distribution of corn florescence, obtaining the heat damage risk days and the heat damage risk accumulated temperature in the corn florescence stage includes:

Obtain the number of days when the surface temperature is greater than or equal to the preset high temperature threshold in the corn flowering stage in the area with abnormal temperature, which is defined as the number of days at risk of heat damage;

The heat damage risk accumulated temperature is the temperature accumulation value in the heat damage risk days, and the calculation formula is:

In the formula, Ts is the value of the accumulated temperature of heat damage risk; n is the number of heat damage risk days; t _i is the temperature value of the ith day of heat damage risk.

Wherein, the preset high temperature threshold is 32-35°C, and preferably, in this embodiment, the preset high temperature threshold is 34°C.

The accumulated temperature index is the product of the heat damage risk days and the heat damage risk accumulated temperature, and the calculation formula is:

IN _t =T _s ·n

In the formula, IN _t is the value of the accumulated temperature index; Ts is the value of the accumulated temperature at risk of heat damage; n is the number of days at risk of heat damage.

According to the surface temperature and the distribution of corn florescence, obtain the heat damage risk days and accumulated temperature index in the corn florescence stage in the abnormal temperature area, and take the accumulated temperature index and heat damage risk days of the corn florescence stage as the evaluation indicators of the high temperature heat damage risk of corn. The high temperature and heat damage risk level is divided into four levels, and the high temperature heat damage risk level at the flowering stage of corn in the abnormal temperature area is obtained.

FIG. 4 is a distribution diagram of the tasseling period of Huanghuaihai summer corn provided according to an embodiment of the present invention. After obtaining the risk level of high temperature heat damage in the flowering stage of corn in the area with abnormal temperature, preventive measures can be taken for areas with a higher risk level of high temperature heat damage. When summer corn is in the tasseling stage, it is the most sensitive period to high temperature. In order to reduce the harm of high temperature to this part of summer corn, measures such as irrigation and cooling, artificial assisted pollination, and foliar spraying can be taken if conditions permit. Irrigation can improve the microclimate in the field, reduce the temperature between plants by 1 to 2 °C, increase the relative humidity, and effectively reduce the harm of high temperature. Artificially assisted pollination increases the amount of pollen falling on the stigma and improves the seed setting rate. Use urea, potassium dihydrogen phosphate or other high-quality foliar fertilizers for multiple sprays to increase the water in the ear of the plant, which can cool and humidify, promote powder dispersion, and provide water and nutrients to the leaves at the same time. Note that the concentration of the fertilizer solution should not be too large. Topdressing fertilizer can increase thousand-grain weight; cut off severely damaged plants, improve the field microclimate, reduce the occurrence of pests and diseases, and do everything possible to increase the productivity of a single plant and reduce yield loss.

The method for evaluating the risk of high temperature heat damage to corn provided by the embodiment of the present invention is based on MODISLST remote sensing image data and uses a moving window to calculate the difference between the mean surface temperature of the center pixel of the window and the surrounding pixel, which is defined as the high temperature abnormality index. According to the high temperature abnormality index, the temperature abnormality area in the Huanghuaihai summer corn growing area was extracted, and the accumulated temperature index and heat damage risk days at the corn flowering stage were used as the evaluation indicators of high temperature heat damage risk of corn, and the high temperature heat damage risk level was divided into four grades. In the abnormal temperature area, the risk level of high temperature heat damage in the flowering stage of corn. The present invention is based on MODIS LST remote sensing image data. Compared with the point source data of meteorological stations used in previous research, the technical advantage of remote sensing image data lies in that it can more accurately reflect the temporal and spatial distribution of high temperature, and more accurately discover large-scale The high temperature abnormal area that occurs in the area provides support for agricultural high temperature risk assessment; the invention efficiently and accurately evaluates the high temperature heat damage risk level in the flowering stage of corn in the abnormal temperature area, provides support for the prevention of high temperature heat damage to corn, and improves the prevention of high temperature heat damage to corn. efficiency and accuracy. Avoid losses caused by high temperature disasters.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still Modifications are made to the technical solutions described in the foregoing embodiments, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (5)

1. an assessment method of corn high temperature heat damage risk, is characterized in that, comprises: Step 1, according to the surface temperature obtained by preprocessing the MODIS LST remote sensing image data, through the moving window algorithm, calculate the high temperature anomaly index, and obtain the temperature anomaly area according to the high temperature anomaly index; Step 2, according to the surface temperature and the distribution of the corn blooming period, obtain the heat damage risk days and the heat damage risk accumulated temperature in the corn blooming stage in the abnormal temperature area; according to the heat damage risk days and the heat damage risk accumulated temperature, calculate accumulated temperature index; Step 3, with reference to the preset corn high temperature heat damage classification standard, according to the heat damage risk days and the accumulated temperature index to obtain the high temperature heat damage risk level of the corn flowering stage in the abnormal temperature area; Wherein, in the step 1, the preprocessing process of the MODIS LST remote sensing image data includes: Convert remote sensing image data coordinates to WGS-84 coordinate system, and convert pixel radiant brightness temperature to pixel surface temperature; In the step 1, the calculation of the high temperature anomaly index by the moving window algorithm includes: Set multiple window scales, count the average surface temperature of pixels under different window scales, and obtain the surface temperature value of the pixel in the center of the window; Calculate the difference between the surface temperature value of the pixel in the center of the window and the average surface temperature of the pixel, where the difference is a high temperature anomaly index; In the step 1, the obtaining of the abnormal temperature area according to the high temperature abnormality index includes: Select the area corresponding to the pixel with the high temperature anomaly index in the corn florescence stage as the temperature anomaly area; in the step 2, the acquisition of the heat damage risk days and the heat damage risk accumulated temperature in the corn florescence stage includes: In the area with abnormal temperature, in the corn flowering stage, the number of days when the surface temperature is greater than or equal to the preset high temperature threshold is defined as the number of days at risk of heat damage; The heat damage risk accumulated temperature is the temperature accumulation value in the heat damage risk days, and the calculation formula is:

In the formula, Ts is the value of the accumulated temperature of heat damage risk; n is the number of heat damage risk days; t _i is the temperature value of the ith day of heat damage risk; The accumulated temperature index is the product of the heat damage risk days and the heat damage risk accumulated temperature, and the calculation formula is: IN _t =T _s ·n In the formula, IN _t is the value of the accumulated temperature index; Ts is the value of the accumulated temperature at risk of heat damage; n is the number of days at risk of heat damage. 2. the assessment method of corn high temperature heat damage risk according to claim 1, is characterized in that, in described step 1, described high temperature abnormality index is: The difference between the surface temperature value of the pixel in the MODIS LST remote sensing image data center and the average surface temperature of the pixel. 3 . The method for evaluating the risk of high temperature heat damage to corn according to claim 1 , wherein the preset high temperature threshold is 32-35° C. 4 . 4 . The method for assessing the risk of high temperature heat damage to corn according to claim 1 , wherein, in the step 2, the distribution of the corn flowering period is obtained by performing interpolation processing using a spatial interpolation tool of spatial analysis. 5 . 5. The assessment method of corn high temperature heat damage risk according to claim 1, wherein in the step 3, the preset corn high temperature heat damage grading standard comprises: Taking the accumulated temperature index and heat damage risk days at the flowering stage of corn as the evaluation indicators of high temperature heat damage risk of corn, through experiments and literature reading, the risk level of high temperature heat damage to corn was divided into grades one to four according to the severity from high to low.

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