Light-nitrogen coupling high-yield regulation and control method and system for canopy of hybrid rice in medium and low yield fields

Abstract

The invention relates to the technical field of intelligent agriculture, and discloses a light-nitrogen coupling high-yield regulation and control method and system for hybrid rice canopies in medium and low yield fields, and the method comprises the steps: obtaining the real-time light transmittance of the hybrid rice canopies from the tillering stage to the heading stage; a nitrogen demand model is constructed based on the lag compensation relation between the real-time light transmittance and the leaf nitrogen accumulation amount, and the target nitrogen application amount is output; a nitrogen application time sequence instruction is generated according to the target nitrogen application amount, the instruction comprises the fertilization time point and the duration, and the adjacent fertilization time interval is dynamically adjusted according to the light transmittance change rate; executing a nitrogen application time sequence instruction and synchronously monitoring the nitrogen accumulation amount of the leaves; and based on a dynamic deviation between the leaf nitrogen accumulation amount and a preset nitrogen accumulation amount threshold value, feeding back a lag compensation relation of the corrected nitrogen demand model before the next growth stage starts. According to the method, efficient coupling of canopy light resource dynamic and accurate nitrogen supply is achieved, and the light and nitrogen resource utilization efficiency of hybrid rice in medium and low yield fields is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of smart agriculture technology, and in particular to a hybrid rice canopy light-nitrogen coupling high-yield regulation method and system for low-yield fields. BACKGROUND

[0002] In the field of smart agriculture technology, the production of rice in low-yield fields often faces the problem of low efficiency of light energy resource utilization. Due to insufficient soil basic fertility or the presence of obstacle factors, the hybrid rice growing process is prone to form an unreasonable canopy structure and uneven leaf distribution, resulting in uneven light distribution within the canopy and low interception and utilization efficiency of photosynthetically active radiation.

[0003] In the prior art, the regulation of the hybrid rice canopy light environment mainly focuses on static methods such as planting density and plant type improvement, and lacks real-time monitoring and response to the dynamic changes of the canopy light distribution during the key growth period. At the same time, nitrogen, as a key nutrient element affecting the photosynthetic capacity and canopy structure of rice, its demand is often dependent on experience or static models, and the dynamic influence of real-time changes in canopy light environment on nitrogen absorption and utilization efficiency is not fully considered, resulting in insufficient spatiotemporal coordination of light and nitrogen resources. The lack of such light-nitrogen coupling mechanism makes it difficult for hybrid rice in low-yield fields to achieve efficient utilization of light energy resources and nitrogen nutrients, limiting the potential of yield. SUMMARY

[0004] The present application provides a hybrid rice canopy light-nitrogen coupling high-yield regulation method and system for low-yield fields, which mainly aims to solve the problem of how to improve the dynamic coupling efficiency of light energy resources and nitrogen nutrients in the canopy of hybrid rice in low-yield fields during the key growth period.

[0005] To achieve the above-mentioned purpose, the present application provides a hybrid rice canopy light-nitrogen coupling high-yield regulation method for low-yield fields, comprising:

[0006] S1. During the key growth period from the tillering stage to the heading stage, the real-time light transmittance of the hybrid rice canopy is obtained;

[0007] S2. Based on the lag compensation relationship between the real-time light transmittance and the leaf nitrogen accumulation, a nitrogen demand model is constructed and a target nitrogen application amount is output;

[0008] S3. A nitrogen application timing instruction is generated according to the target nitrogen application amount, the nitrogen application timing instruction includes a fertilization time point and a duration, and the interval between adjacent fertilization times is dynamically adjusted by the light transmittance change rate;

[0009] S4. The nitrogen application timing instruction is executed, and the leaf nitrogen accumulation of the hybrid rice is monitored synchronously;

[0010] S5. Based on the dynamic deviation of the leaf nitrogen accumulation amount from the preset nitrogen accumulation threshold, feedback correction is made to the lag compensation relationship of the nitrogen requirement model before the next growth stage starts.

[0011] Optionally, the real-time light transmittance of the hybrid rice canopy is obtained by:

[0012] deploying an array of light intensity sensors above the hybrid rice canopy to collect incident light intensity of solar radiation;

[0013] deploying an array of transmitted light sensors at symmetrical positions below the hybrid rice canopy to collect transmitted light intensity penetrating the canopy;

[0014] Based on the incident light intensity and the transmitted light intensity, the instantaneous light transmittance ratio is calculated;

[0015] The instantaneous light transmittance ratio is time series filtered to obtain the real-time light transmittance of the hybrid rice canopy.

[0016] Optionally, the lag compensation relationship based on the real-time light transmittance and the leaf nitrogen accumulation amount comprises:

[0017] Obtain historical light transmittance and corresponding leaf nitrogen accumulation measured value in historical growth period;

[0018] Shift the historical light transmittance backward by a preset number of days to align with the leaf nitrogen accumulation measured value;

[0019] Calculate the correlation coefficient of the shifted historical light transmittance and the leaf nitrogen accumulation, and iteratively adjust the shift days until the correlation coefficient reaches the maximum value;

[0020] The shift days corresponding to the maximum correlation coefficient are taken as the lag compensation parameter.

[0021] Optionally, the nitrogen requirement model is constructed and the target nitrogen application amount is outputted by:

[0022] Shift the real-time light transmittance by the lag compensation parameter to obtain the compensated light transmittance of the hybrid rice canopy;

[0023] Establish a linear regression model of the compensated light transmittance and the target nitrogen accumulation amount;

[0024] N target =k·T comp +N soil +N residual -N loss

[0025] wherein, T comp is the compensated light transmittance, k is the light-nitrogen conversion efficiency factor, N target is the target nitrogen accumulation amount, N soilis the soil available nitrogen content measured before sowing, N residual is the residual nitrogen not utilized in the early stage, N loss is the ammonia volatilization loss amount;

[0026] inputting the current light transmittance into the linear regression model, outputting a target nitrogen application amount.

[0027] Optionally, the generating of the nitrogen application timing instruction according to the target nitrogen application amount comprises:

[0028] decomposing the target nitrogen application amount into a total amount of nitrogen application operations;

[0029] calculating an absolute value of a light transmittance change rate of adjacent time points;

[0030] shortening an adjacent fertilization time interval when the absolute value of the light transmittance change rate increases;

[0031] lengthening the adjacent fertilization time interval when the absolute value of the light transmittance change rate decreases;

[0032] generating a set of fertilization time points of hybrid rice based on the dynamically adjusted time interval, and assigning the total amount of nitrogen application operations to each fertilization time point in the set of fertilization time points.

[0033] Optionally, the synchronously monitoring of the leaf nitrogen accumulation amount of the hybrid rice comprises:

[0034] collecting a functional leaf sample in the middle of the canopy of the hybrid rice after each nitrogen application operation;

[0035] subjecting the functional leaf sample to decolorization and drying treatment to obtain dry matter;

[0036] measuring the nitrogen content of the dry matter by means of micro-Kjeldahl nitrogen determination method, and calculating the leaf nitrogen accumulation amount per unit area in combination with the leaf area of the sample.

[0037] Optionally, the monitoring and verification of the leaf nitrogen accumulation amount comprises:

[0038] triggering a resampling mechanism when the coefficient of variation of the continuously monitored leaf nitrogen accumulation amount exceeds a preset variation threshold;

[0039] recollecting a backup leaf sample at the same position of the canopy of the hybrid rice;

[0040] if the difference between the measured value of the backup leaf sample and the original sample exceeds a fault tolerance range, enabling laboratory arbitration detection to update the leaf nitrogen accumulation amount record with the arbitration detection result.

[0041] Optionally, the determination of the duration of the nitrogen application timing instruction is as follows:

[0042] obtaining a current soil infiltration rate category:

[0043] when the soil is of the clay category, extending the duration of the nitrogen application operation;

[0044] when the soil is of the sandy category, shortening the duration of the nitrogen application operation.

[0045] Optionally, the feedback correction of the hysteresis compensation relationship of the nitrogen requirement model before the start of the next growth stage comprises:

[0046] calculating a dynamic deviation of the leaf nitrogen accumulation amount from a preset nitrogen accumulation amount threshold;

[0047] when the dynamic deviation is continuously positive, decreasing the day value of the hysteresis compensation parameter;

[0048] when the dynamic deviation is continuously negative, increasing the day value of the hysteresis compensation parameter;

[0049] inputting the corrected hysteresis compensation parameter into the nitrogen requirement model of the next growth stage;

[0050] generating a hysteresis compensation relationship correction report at the end of the heading stage.

[0051] To solve the above problems, the application further provides a middle-low yield field hybrid rice canopy light-nitrogen coupling high yield regulation system, which comprises:

[0052] a real-time light transmittance acquisition module, configured to acquire the real-time light transmittance of the hybrid rice canopy during the key growth period from the tillering peak stage to the heading stage;

[0053] a nitrogen requirement model construction module, configured to construct a nitrogen requirement model and output a target nitrogen application amount based on a hysteresis compensation relationship between the real-time light transmittance and the leaf nitrogen accumulation amount;

[0054] a nitrogen application timing instruction generation module, configured to generate a nitrogen application timing instruction according to the target nitrogen application amount, wherein the nitrogen application timing instruction comprises a fertilization time point and a duration, and the interval between adjacent fertilization time points is dynamically adjusted according to the light transmittance change rate;

[0055] a leaf nitrogen accumulation amount monitoring module, configured to execute the nitrogen application timing instruction and synchronously monitor the leaf nitrogen accumulation amount of the hybrid rice;

[0056] a hysteresis compensation relationship correction module, configured to feedback correct the hysteresis compensation relationship of the nitrogen requirement model before the start of the next growth stage based on a dynamic deviation of the leaf nitrogen accumulation amount from a preset nitrogen accumulation amount threshold.

[0057] The application provides a middle-low yield field hybrid rice canopy light-nitrogen coupling high yield regulation method and system, which has the following remarkable technical effects: first, by acquiring the canopy light transmittance in real time in the key growth period and establishing the hysteresis compensation relationship between the canopy light transmittance and the leaf nitrogen accumulation, a dynamic nitrogen demand model is constructed, the dynamic influence of the current canopy light environment on the future nitrogen demand can be accurately quantified, the accuracy and timeliness of the nitrogen demand prediction are significantly improved, and the hysteresis of the traditional experience judgment or static model is overcome; second, based on the target nitrogen application amount and according to the light transmittance change rate, a nitrogen application time interval is dynamically adjusted to generate a nitrogen application time sequence instruction, so that the timing and rhythm of nitrogen supply can sensitively respond to the change and dynamics of the canopy structure and light distribution, the real-time matching of the light resource change and the nitrogen supply is realized, and the misalignment of the nitrogen supply and the rice physiological demand in time is effectively reduced; and finally, by synchronously monitoring the leaf nitrogen accumulation and dynamically correcting the hysteresis compensation relationship based on the dynamic deviation of the leaf nitrogen accumulation from the preset threshold, a closed-loop regulation mechanism is formed, and the adaptability and robustness of the model to the environmental changes of different fields and different growth stages are enhanced. The application effectively improves the synergistic utilization efficiency of the canopy light energy resources and the nitrogen nutrients of the middle-low yield field hybrid rice, and provides technical support for high yield and stable yield. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 A flowchart of the middle-low yield field hybrid rice canopy light-nitrogen coupling high yield regulation method provided by an embodiment of the application is shown.

[0059] Figure 2 A functional module diagram of the middle-low yield field hybrid rice canopy light-nitrogen coupling high yield regulation system provided by an embodiment of the application is shown.

[0060] The implementation, functional characteristics and advantages of the application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0061] It should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0062] The embodiment of the application provides a kind of middle-low yield field hybrid rice canopy light nitrogen coupling high yield regulation method.The execution subject of the middle-low yield field hybrid rice canopy light nitrogen coupling high yield regulation method includes but is not limited to at least one of the electronic devices such as server, terminal etc., which can be configured to execute the method provided in the embodiment of the application.In other words, the middle-low yield field hybrid rice canopy light nitrogen coupling high yield regulation method can be executed by software or hardware installed in terminal device or server device.The server includes but is not limited to: single server, server cluster, cloud server or cloud server cluster etc.The server can be independent server, can also be cloud server providing cloud service, cloud database, cloud computing, cloud function, cloud storage, network service, cloud communication, middleware service, domain name service, security service, content distribution network (Content Delivery Network, CDN), and big data and artificial intelligence platform etc.Basic cloud computing services.

[0063] Referring to Figure 1 As shown in the figure, the flowchart of the middle-low yield field hybrid rice canopy light nitrogen coupling high yield regulation method provided in the embodiment of the application.In this embodiment, the middle-low yield field hybrid rice canopy light nitrogen coupling high yield regulation method includes:

[0064] S1. In the key growth period from tillering peak period to heading period, the real-time light transmittance of hybrid rice canopy is obtained.

[0065] In the embodiment of the application, the real-time light transmittance of hybrid rice canopy includes:

[0066] Deploy light intensity sensor array above hybrid rice canopy, collect incident light intensity of solar radiation;

[0067] Deploy transmittance light sensor array at symmetrical position below hybrid rice canopy, collect transmittance light intensity penetrating canopy;

[0068] Based on the incident light intensity and the transmittance light intensity, the instantaneous light transmittance ratio is calculated;

[0069] Time series filtering is performed on the instantaneous light transmittance ratio, to obtain the real-time light transmittance of hybrid rice canopy.

[0070] In detail, tillering peak period is the period when the number of tillers reaches the peak in the growth process of rice, and the rice plant grows vigorously at this stage, with a large demand for nutrients and light;heading period refers to the period from the beginning of panicle differentiation to flowering, which is the key stage of yield formation of rice, and its growth condition directly affects the final yield.

[0071] In detail, the hybrid rice canopy refers to the hierarchical structure of leaves, stems and other organs of the aboveground part of hybrid rice plants in the vertical direction, which plays an important role in intercepting and transmitting solar radiation; the real-time light transmittance refers to the proportion of solar radiation transmitted through the hybrid rice canopy at a specific time point, which is used to reflect the light transmittance ability of the canopy, and is an important basis for subsequent nitrogen regulation.

[0072] In detail, the light intensity sensor array is a device composed of multiple light intensity sensors arranged according to certain rules, which is used to collect light intensity data of solar radiation.

[0073] In detail, the incident light intensity refers to the light intensity of solar radiation reaching above the hybrid rice canopy, which directly affects the calculation of the light transmittance of the canopy; the transmitted light intensity refers to the light intensity of solar radiation reaching below the hybrid rice canopy after passing through the canopy, which can be compared with the incident light intensity to calculate the light transmittance.

[0074] In detail, the instantaneous light transmittance ratio is the ratio of the transmitted light intensity below the canopy to the incident light intensity above the canopy at the same time point, which is used to preliminarily measure the light transmittance ability of the canopy; the time series filtering is a method for processing the instantaneous light transmittance ratio data collected in time sequence, which eliminates noise and fluctuations in the data to obtain data that can better reflect the trend of real light transmittance.

[0075] In detail, the light intensity sensor array is deployed at a suitable position above the hybrid rice canopy, which includes multiple light intensity sensors, such as photosynthetically active radiation sensors, to ensure that the incident light intensity of solar radiation can be accurately collected. At the same time, the transmitted light sensor array is deployed at a position symmetric to the upper sensor below the canopy, which also uses the same type of sensor to ensure the consistency and comparability of the collected data.

[0076] In detail, the data is collected in real time through the sensor array, and a reasonable collection frequency is set, such as collecting incident light intensity and transmitted light intensity data every 10 minutes. During the collection process, the working state of the sensor is ensured to be normal to avoid inaccurate data caused by equipment failure.

[0077] In detail, for each collected incident light intensity and transmitted light intensity data, the instantaneous light transmittance ratio is calculated using the formula, that is, the instantaneous light transmittance ratio is equal to the transmitted light intensity divided by the incident light intensity. For example, if the incident light intensity collected at a certain time is I in , the transmitted light intensity is I out , then the instantaneous light transmittance ratio is I out / I in .

[0078] In detail, the calculated instantaneous transmittance ratio is subjected to time series filtering. A moving average filtering algorithm is adopted, and a suitable filtering window size is selected, such as 12 time points (equivalent to 2 hours of data). Through the algorithm, the data is smoothed to eliminate noise interference caused by light changes and other factors in a short time, so as to obtain real-time transmittance that can truly reflect the change trend of hybrid rice canopy transmittance.

[0079] In general, this step can accurately obtain the real-time transmittance of the hybrid rice canopy by symmetrically deploying the sensor array above and below the canopy and performing accurate data acquisition and processing, thereby providing a reliable data basis for subsequent nitrogen demand model construction and nitrogen application regulation based on the light-nitrogen coupling relationship, solving the problem of low nitrogen regulation efficiency caused by inaccurate transmittance measurement in the background technology, and making the light environment monitoring of rice growth process more accurate.

[0080] S2. Construct a nitrogen demand model based on the lag compensation relationship between the real-time transmittance and the leaf nitrogen accumulation amount, and output a target nitrogen application amount.

[0081] In the embodiment of the present application, the lag compensation relationship based on the real-time transmittance and the leaf nitrogen accumulation amount comprises:

[0082] Obtaining historical transmittance and corresponding leaf nitrogen accumulation measured value of historical growth period;

[0083] The historical transmittance is shifted backward by a preset number of days, and is aligned with the leaf nitrogen accumulation measured value;

[0084] Calculate the correlation coefficient of the shifted historical transmittance and the leaf nitrogen accumulation, and iteratively adjust the shift days until the correlation coefficient reaches the maximum value;

[0085] The shift days corresponding to the maximum correlation coefficient are taken as the lag compensation parameter.

[0086] In detail, the construction of the nitrogen demand model and the output of the target nitrogen application amount comprise:

[0087] Shift the real-time transmittance according to the lag compensation parameter to obtain the compensation transmittance of the hybrid rice canopy;

[0088] Establish a linear regression model of the compensation transmittance and the target nitrogen accumulation amount;

[0089] N target =k·T comp +N soil +N residual -N loss

[0090] Wherein, T comp is the compensation transmittance, k is the light-nitrogen conversion efficiency factor, Ntarget is the target nitrogen accumulation amount, N soil is the soil available nitrogen content measured before sowing, N residual is the residual nitrogen not utilized in the previous stage, N loss is the ammonia volatilization loss amount;

[0091] inputting the current light transmittance into the linear regression model, outputting the target nitrogen application amount.

[0092] In detail, the historical growth period refers to the complete growth stage of hybrid rice from the tillering stage to the heading stage in the past growth process, which contains the key data of light and nitrogen demand of rice; the historical light transmittance is the light transmittance data of the hybrid rice canopy obtained by collecting through the light intensity sensor array and processing by time series filtering in the historical growth period, which reflects the canopy light transmittance ability of the same growth stage in the past.

[0093] In detail, the measured value of leaf nitrogen accumulation amount is the actual measurement value of unit area leaf nitrogen content obtained by sampling, decolorizing, drying and Kjeldahl nitrogen determination of hybrid rice leaves, which reflects the actual accumulation status of nitrogen in the growth process of rice.

[0094] In detail, the preset number of days is the initial time interval of backward shift preset when processing the historical light transmittance data, which is used as the starting adjustment value for finding the optimal lag compensation parameter; the correlation coefficient is a statistical index for measuring the linear correlation degree between the shifted historical light transmittance and the measured value of leaf nitrogen accumulation amount, which has a value range of-1 to 1, and the greater the absolute value, the stronger the correlation.

[0095] In detail, the lag compensation parameter is the shifted number of days corresponding to the maximum correlation coefficient obtained by iteratively adjusting the shifted number of days, which is used to correct the physiological response lag time between the real-time light transmittance and the leaf nitrogen accumulation amount.

[0096] In detail, the compensated light transmittance is the light transmittance value obtained by time shifting the real-time light transmittance according to the lag compensation parameter, which eliminates the time difference caused by the physiological response lag of plants.

[0097] In detail, the linear regression model is a mathematical model established based on the linear relationship between the compensated light transmittance and the target nitrogen accumulation amount, which is used to predict the nitrogen accumulation amount required for the growth of hybrid rice.

[0098] In detail, the light-nitrogen conversion efficiency factor is a parameter in the linear regression model representing the influence degree of the compensated light transmittance on the target nitrogen accumulation amount, which reflects the change amount of the target nitrogen accumulation amount corresponding to the unit change of the compensated light transmittance, and is determined by regression analysis of historical data.

[0099] In detail, the target nitrogen accumulation amount is a target value of nitrogen accumulation amount per unit area of a leaf required for hybrid rice at the current growth stage to achieve high yield, and is calculated by a linear regression model, with units of grams per square meter.

[0100] In detail, the soil available nitrogen content is the nitrogen content in the soil that can be directly absorbed and utilized by plants before sowing, which is determined by potassium chloride extraction-indigo blue colorimetry, with units of grams per square meter.

[0101] In detail, the residual nitrogen not utilized in the early stage is the nitrogen content in the soil that is not absorbed and utilized by rice in the previous fertilization stage and remains in the soil, with units of grams per square meter, which is determined by fertilization records and soil nitrogen balance calculation.

[0102] In detail, the ammonia volatilization loss amount is the nitrogen loss amount caused by ammonia volatilization after the nitrogen fertilizer is applied to the soil, with units of grams per square meter, which is estimated based on parameters such as soil pH, temperature, and water content.

[0103] Further, historical light transmittance data of the hybrid rice of the same variety from 3-5 years ago during the tillering stage to the heading stage is extracted from the database. The data is collected by an array of light intensity sensors at a frequency of 10 minutes per time, and the daily average light transmittance is obtained after 12-point moving average filtering processing.

[0104] Further, the measured value of leaf nitrogen accumulation amount collected every week during the corresponding growth period is synchronously obtained: 10 functional leaves of rice in the middle of the canopy are selected each time, and the nitrogen content is determined by micro-Kjeldahl nitrogen determination method after decolorization by 95% ethanol and drying at 75°C to constant weight, and the accumulation amount per unit area (g / m 2 ) is calculated in combination with leaf area.

[0105] Further, the initial preset number of days is set to 1 day, and the historical light transmittance data is shifted back by the number of days, so that the light transmittance time point is aligned with the sampling time point of the measured value of leaf nitrogen accumulation amount. For example, if a nitrogen accumulation amount measured value is collected on the 20th day of the growth period, the light transmittance on the 19th day is shifted to the 20th day.

[0106] Further, the Pearson correlation coefficient algorithm is used to calculate the correlation coefficient between the shifted historical light transmittance and the measured value of leaf nitrogen accumulation amount based on the shifted light transmittance and nitrogen accumulation amount.

[0107] Further, starting from the preset number of days 1, the number of days is increased by 1 each time (up to 10 days), and the shifting and calculation process is repeated, and the correlation coefficient corresponding to each number of days is recorded. When the correlation coefficient reaches the maximum value and subsequent days no longer significantly improve (such as an increase of <0.05), iteration is stopped.

[0108] Further, the maximum correlation coefficient corresponds to the number of days of translation as a lag compensation parameter. For example, when the correlation coefficient reaches 0.8 (significance correlation threshold ≥ 0.7) when translated by 5 days, the lag compensation parameter is 5 days, which reflects the lag time of the light transmittance change affecting nitrogen accumulation.

[0109] In detail, according to the lag compensation parameter d opt , the current real-time light transmittance T(t) is time-shifted to obtain the compensated light transmittance T comp = T(t-d opt ). For example, the current light transmittance is 60%, d opt = 5 days, and the compensated light transmittance T comp is the light transmittance 58% 5 days ago, eliminating the effect of physiological response lag.

[0110] Further, the compensated light transmittance and the corresponding target nitrogen accumulation data (considering soil available nitrogen, residual nitrogen and ammonia volatilization loss) during the historical growth period are collected.

[0111] Further, the least squares method is used to fit the regression coefficient k: k = ∑(T (t-d ) * N ) / ∑(T

[0112] (t-d )2), where N

[0113] is the average value. For example, the historical data fitting obtains k = 0.2 g / m 2 / %, indicating that a unit of light transmittance corresponds to 0.2 g / m 2 of nitrogen demand.

[0114] Further, the current compensated light transmittance is substituted into the linear regression model to calculate the target nitrogen accumulation. For example, the compensated light transmittance is 58%, the soil available nitrogen content measured before sowing is 15 g / m 2 , the residual nitrogen not utilized in the early stage is 3 g / m 2 , and the ammonia volatilization loss is 2 g / m 2 , then the target nitrogen accumulation is 27.6 g / m 2 .

[0115] Overall, this step dynamically establishes the hysteresis compensation relationship between real-time light transmittance and leaf nitrogen accumulation and builds a nitrogen demand model. The traditional method does not consider the time difference between light transmittance and nitrogen accumulation, which may lead to mismatch between nitrogen application amount and actual demand. However, this step determines the hysteresis compensation parameter through historical data iteration optimization, so that the model can accurately reflect the influence of current light transmittance on future nitrogen demand. At the same time, the nitrogen demand model considers the soil background nitrogen, residual nitrogen and volatilization loss, avoiding the waste or deficiency of nitrogen caused by blind fertilization, and improving the utilization rate of nitrogen fertilizer. It provides a precise nitrogen demand prediction method for high-yield regulation of hybrid rice in low-yield fields, and effectively improves the efficiency of light-nitrogen coupling regulation.

[0116] S3. According to the target nitrogen application amount, a nitrogen application time sequence instruction is generated, the nitrogen application time sequence instruction includes a fertilization time point and a duration, and adjacent fertilization time intervals are dynamically adjusted by a light transmittance change rate.

[0117] In the embodiment of the application, the nitrogen application time sequence instruction is generated according to the target nitrogen application amount, comprising:

[0118] The target nitrogen application amount is divided into a total amount of several nitrogen application operations;

[0119] The absolute value of the light transmittance change rate of adjacent time points is calculated;

[0120] When the absolute value of the light transmittance change rate increases, the adjacent fertilization time interval is shortened;

[0121] When the absolute value of the light transmittance change rate decreases, the adjacent fertilization time interval is extended;

[0122] A set of fertilization time points of hybrid rice is generated based on the dynamically adjusted time interval, and a total amount of equal nitrogen application operations is allocated to each fertilization time point in the set of fertilization time points.

[0123] In detail, the target nitrogen application amount is calculated by a nitrogen demand model, which is the total amount of nitrogen required by hybrid rice in the current growth stage to achieve high yield, and its value considers multiple factors such as light transmittance and soil nitrogen content. The nitrogen application time sequence instruction is generated according to the target nitrogen application amount, which includes specific fertilization time points, duration of each fertilization and amount of each fertilization, and is used to guide actual fertilization operation.

[0124] In detail, the fertilization time point refers to the specific time for arranging fertilization operation in the growth process of hybrid rice, which is accurate to a specific date in days; the duration is the length of time experienced from the beginning to the end of each fertilization operation, which is hours, and its setting is related to soil texture and other factors.

[0125] In detail, the adjacent fertilization time interval refers to the time difference between two consecutive fertilization operations, in units of days, which is dynamically adjusted according to the light transmittance change rate; the light transmittance change rate is the absolute value of the light transmittance difference between two adjacent time points, which is used to measure the speed of change of the hybrid rice canopy light transmittance and reflect the dynamic change of the canopy structure.

[0126] In detail, the total amount of nitrogen application operation is the amount of nitrogen required for each fertilization operation after the target nitrogen application amount is decomposed, and the total amount of each nitrogen application operation is usually equal; the set of fertilization time points is a sequence composed of multiple dynamically adjusted fertilization time points, which constitutes a complete fertilization time arrangement plan.

[0127] Further, according to the expected growth days of hybrid rice from the tillering peak period to the heading period and the nitrogen absorption rule, the target nitrogen application amount is decomposed into several nitrogen application operations. For example, if the target nitrogen application amount is 28 grams per square meter and the growth period is about 40 days, it can be decomposed into 6-8 times of nitrogen application, with each time of nitrogen application amount being about 3.5-4.7 grams per square meter; the target nitrogen application amount is evenly distributed to each nitrogen application operation to ensure equal amount of nitrogen application each time to maintain the stability of nitrogen supply during rice growth.

[0128] In detail, real-time light transmittance data at adjacent time points (such as every day) is obtained, which is collected by the light intensity sensor array and obtained after time series filtering processing; for the light transmittance T(n) and T(n+1) of the nth day and the (n+1)th day, the absolute value of the light transmittance change rate is calculated as |T(n+1)-T(n)|, in units of % / day.

[0129] Further, according to the general fertilization rule in the early growth period of rice, an initial adjacent fertilization time interval is set, such as 3 days; the current light transmittance change rate is compared with the change rate in the previous time interval. If the absolute value of the current change rate increases, it indicates that the canopy structure changes faster and the demand for nitrogen by rice may increase; if the absolute value of the change rate decreases, it indicates that the canopy structure changes slowly and the demand for nitrogen is relatively stable.

[0130] Further, when the absolute value of the light transmittance change rate increases, the adjacent fertilization time interval is shortened by 1 day (such as from 3 days to 2 days) to supplement nitrogen in time; when the absolute value of the change rate decreases, the interval is extended by 1 day (such as from 3 days to 4 days) to avoid excessive application of nitrogen.

[0131] Further, a specific date in the current growth period is taken as the starting time point of the first fertilization, such as the 15th day of the tillering peak period; according to the adjusted adjacent fertilization time interval, the time points of subsequent fertilizations are calculated in turn. For example, the first fertilization is on the 15th day, with an interval of 2 days, so the subsequent time points are the 17th day, the 19th day, etc., forming a set of fertilization time points.

[0132] Further, the total amount of each nitrogen application operation is allocated to each time point in the set of fertilization time points to ensure that the amount of nitrogen applied at each fertilization time point is equal, such as 4 grams per square meter for each nitrogen application; the fertilization time points, the amount of nitrogen applied each time, and the duration determined according to the soil texture (such as extending the duration for clay soil and shortening the duration for sandy soil) are integrated into the nitrogen application timing instructions, which are stored and output in a structured data format, such as {“fertilization time”:[15th day, 17th day, …], “nitrogen application amount”:[4g / m 2 ,4g / m 2 ,…],“duration”:[5h,5h,…]}.

[0133] In summary, this step dynamically adjusts the fertilization time interval according to the light transmittance rate, and monitors the light transmittance rate in real time and adjusts the fertilization timing accordingly, so that the fertilization timing matches the nitrogen demand rhythm of rice, avoiding nitrogen supply lag or excess caused by changes in canopy structure, improving nitrogen utilization efficiency, reducing nitrogen loss and waste, and effectively improving the precision of hybrid rice canopy light-nitrogen coupling regulation in low-yield fields.

[0134] S4. Execute the nitrogen application timing instructions and simultaneously monitor the leaf nitrogen accumulation of hybrid rice.

[0135] In the embodiments of the present application, the simultaneous monitoring of the leaf nitrogen accumulation of hybrid rice includes:

[0136] After each nitrogen application operation, functional leaf samples are collected from the middle of the hybrid rice canopy;

[0137] The functional leaf samples are subjected to decolorization and drying treatment to obtain dry matter;

[0138] The nitrogen content of the dry matter is determined by micro-Kjeldahl nitrogen determination method, and the leaf nitrogen accumulation per unit area is calculated in combination with the sample leaf area.

[0139] In detail, the monitoring and verification of the leaf nitrogen accumulation includes:

[0140] When the coefficient of variation of the continuously monitored leaf nitrogen accumulation exceeds the preset variation threshold, a resampling mechanism is triggered;

[0141] Backup leaf samples are re-collected at the same position of the hybrid rice canopy;

[0142] If the difference between the measured value of the backup leaf sample and the original sample exceeds the fault tolerance range, laboratory arbitration detection is enabled to update the leaf nitrogen accumulation record with the arbitration detection result.

[0143] In the embodiments of the present application, the determination of the duration of the nitrogen application timing instructions is as follows:

[0144] Obtaining a current soil permeation rate category:

[0145] When the soil is of a clay category, extending a nitrogen application operation duration;

[0146] When the soil is of a sandy category, shortening a nitrogen application operation duration.

[0147] In detail, the nitrogen application timing instruction refers to a specific operation instruction including a fertilization time point, a nitrogen amount per application, and a fertilization duration, which is dynamically generated from a target nitrogen amount combined with a light transmittance change rate, and is used to guide an actual fertilization operation; the synchronous monitoring refers to real-time collection and determination of hybrid rice leaf nitrogen accumulation amount while performing the nitrogen application operation, so as to realize instant feedback of the fertilization effect.

[0148] In detail, the functional leaf sample refers to a leaf selected from a middle part of a hybrid rice canopy, which has sufficient photosynthetic capacity, and the nitrogen accumulation amount of such leaf can accurately reflect the nitrogen nutrition status of the plant.

[0149] In detail, the decolorization treatment is to remove chlorophyll in the leaf sample by a chemical reagent (such as 95% ethanol), so as to avoid interference of the pigment on subsequent nitrogen content determination, and make the determination result more accurate; the drying treatment is to place the leaf sample under a specific temperature (such as 75°C after 105°C fixation) for drying to constant weight, so as to remove water to obtain dry matter, and facilitate accurate determination of the nitrogen content; the micro-Kjeldahl digestion method is a standard method for determining the nitrogen content in organic compounds by digestion, distillation, and titration, which has high precision, and is suitable for nitrogen analysis of leaf and other trace samples.

[0150] In detail, the leaf nitrogen accumulation amount per unit area refers to the mass of nitrogen contained in each square meter of leaf, which is calculated by combining the nitrogen content determination value with the leaf area, and is a key index for measuring the nitrogen nutrition status of the plant.

[0151] In detail, the coefficient of variation is an index for measuring the dispersion degree of continuous monitoring data, and the calculation method is the ratio of the data standard deviation to the average value, which is used to judge the stability and reliability of the monitoring data; the preset variation threshold is a pre-set critical value of the coefficient of variation, when the coefficient of variation of the continuous monitoring data exceeds the value, it indicates that the data fluctuation is abnormal, and the resampling mechanism needs to be triggered.

[0152] In detail, the resampling mechanism refers to a procedure of re-collecting leaf samples at the same canopy position when the monitoring data is abnormal, so as to exclude the influence of single sampling error on the result; the backup leaf sample is an additional sample collected and saved at the same time as the first sampling, which is used for repeated determination when needed, to verify the accuracy of the initial determination result; the fault tolerance range is the difference limit of the determination values of the backup sample and the original sample, if the difference exceeds the range, more accurate laboratory arbitration detection needs to be started.

[0153] In detail, the laboratory arbitration detection refers to that a professional laboratory uses high-precision instruments (such as an elemental analyzer) to measure the nitrogen content of the leaf sample, and the result is used as the basis for the final data record.

[0154] In detail, the soil penetration rate category is classified according to the classification of soil texture on the water penetration capacity, mainly divided into clay soil (low penetration rate) and sandy soil (high penetration rate), which is used to determine the duration of nitrogen application operation; the clay category soil refers to the soil with high clay content, which has fine and dense particles and slow water penetration, so the nitrogen application duration needs to be extended to avoid the accumulation of nitrogen on the ground; the sandy category soil refers to the soil with high sand content, which has loose particles and rapid water penetration, so the nitrogen application duration needs to be shortened to reduce the leaching loss of nitrogen.

[0155] Further, according to the set of fertilizer application time points in the nitrogen application timing instruction, the fertilizer application equipment is started at a preset date (such as the 15th day, the 17th day, etc.), to ensure that the fertilizer application operation is synchronized with the rice growth cycle; according to the total amount of single nitrogen application operation (such as 4 grams per square meter) allocated by the instruction, the nitrogen fertilizer is uniformly applied through the metering fertilizer application equipment (such as an electric fertilizer applicator), to ensure that the amount of each fertilizer application is accurate and consistent; the 0-20cm soil layer sample is collected, and the mechanical composition is determined by the screening method: the clay content > 30% is determined as clay soil, and the sand content > 50% is determined as sandy soil; the clay soil extends the nitrogen application duration to 4-6 hours (the base duration of 3 hours + the extension amount), and the sandy soil shortens it to 1-2 hours (the base duration - the reduction amount), and the duration adjustment is realized by controlling the release rate of the fertilizer application equipment.

[0156] Further, 3 days after each nitrogen application operation, 9:00-11:00 of sunny weather is selected, at which time the leaf physiological activity is vigorous and the nitrogen distribution is uniform; 5 healthy rice plants are selected in the middle of the canopy, and the 3rd fully expanded functional leaf is collected from the bottom up, and a 10cm*2cm sample is taken from the middle of each leaf to avoid the tip and base parts.

[0157] In detail, the sample treatment includes: placing the leaf sample in a 95% ethanol solution, soaking in a 50°C constant temperature water bath until the leaf is completely white (about 2-3 hours), removing chlorophyll and other pigments; removing the decolorized sample, rinsing the surface ethanol with deionized water, absorbing the water with filter paper, and placing it in an oven, first at 105°C for 30 minutes, then at 75°C for drying to constant weight (about 12-24 hours), and weighing the dry matter.

[0158] Further, take 0.5 grams of dry matter sample, put it into a Kjeldahl flask, add 3 grams of potassium sulfate-copper sulfate mixed catalyst (K2SO4: CuSO4 = 10:1) and 5 milliliters of concentrated sulfuric acid, and heat and digest in a fume hood until the solution is clear and transparent (about 2 hours) using a Kjeldahl nitrogen analyzer, so that the organic nitrogen is converted into ammonium sulfate; after the digestion solution is cooled, it is transferred to a distillation device, an excess of sodium hydroxide solution is added to make it alkaline, and heating and distillation is performed, and the released ammonia gas is absorbed with 2% boric acid solution; the absorption solution is titrated with 0.01 mol / L hydrochloric acid standard solution, and the end point is judged with a methyl red-bromocresol green mixed indicator (the color changes from blue-green to gray-red), and the amount of hydrochloric acid used is recorded.

[0159] In detail, the actual area of the leaf sample is measured using a leaf area meter, or is estimated by a length-width correction coefficient (0.85); the nitrogen content (N% = (V*C*0.014) / m*100%, where V is the volume of hydrochloric acid, C is the concentration, and m is the sample mass) is calculated according to the titration result, and is multiplied by the leaf area and converted into the nitrogen accumulation amount (g / m 2 ) per unit area (m 2 ).

[0160] Further, the nitrogen accumulation amount data of 5 consecutive monitoring (such as N1, N2, N3, N4, N5) are recorded, the average μ and the standard deviation σ are calculated, and the coefficient of variation CV = (σ / μ)*100% is calculated; the variation threshold is preset to be 15%, and if CV>15%, the resampling mechanism is triggered.

[0161] Further, the resampling execution includes: re-collecting 10 functional leaf samples of rice near the original sampling position (error ≤50 cm), repeating the above sampling, processing and measuring processes, and obtaining the backup sample measurement value N backup ; the difference rate between the backup sample and the original sample measurement value is calculated as p = |N backup -N original | / N original *100%, and if the difference rate is >10%, the original sample and the backup sample are sent to a third-party laboratory for arbitration detection with an elemental analyzer, and the nitrogen accumulation amount record in the database is updated with the arbitration result.

[0162] In summary, this step accurately executes the nitrogen application timing instruction and combines real-time leaf nitrogen accumulation monitoring. Dynamically adjusting the nitrogen application duration can avoid nitrogen surface residue in clay soil or nitrogen leaching in sandy soil, improving nitrogen fertilizer utilization efficiency; the standardized sampling and measuring process ensures the reliability of the nitrogen accumulation amount data, and the strict checking mechanism eliminates the interference of accidental errors on the regulation model, making the subsequent model correction more scientific, and finally realizing the closed-loop optimization of light and nitrogen coupling regulation, and improving the yield stability of hybrid rice in medium and low yield fields.

[0163] S5. Based on the dynamic deviation of the leaf nitrogen accumulation amount and the preset nitrogen accumulation threshold, feedback correction is made to the lag compensation relationship of the nitrogen requirement model before the start of the next growth stage.

[0164] In the embodiments of the present application, the feedback correction of the lag compensation relationship of the nitrogen requirement model before the start of the next growth stage comprises:

[0165] The dynamic deviation of the leaf nitrogen accumulation amount and the preset nitrogen accumulation threshold is calculated.

[0166] When the dynamic deviation is continuously positive, the value of the lag compensation parameter in days is reduced.

[0167] When the dynamic deviation is continuously negative, the value of the lag compensation parameter in days is increased.

[0168] The corrected lag compensation parameter is input into the nitrogen requirement model of the next growth stage.

[0169] A lag compensation relationship correction report is generated at the end of the heading stage.

[0170] In detail, the leaf nitrogen accumulation amount refers to the mass of nitrogen in unit area of hybrid rice leaf determined by sampling, which reflects the absorption and accumulation of nitrogen during the growth of rice; the preset nitrogen accumulation threshold is a reference value of leaf nitrogen accumulation amount preset according to the characteristics of hybrid rice varieties, growth stages and high yield targets, and is used to measure whether the actual nitrogen accumulation amount meets the growth demand.

[0171] In detail, the dynamic deviation is the difference between the leaf nitrogen accumulation amount and the preset nitrogen accumulation threshold, which is used to represent the deviation degree of the current nitrogen accumulation condition from the target state; the lag compensation parameter is a translation number of days for correcting the time lag relationship between the real-time light transmittance and the leaf nitrogen accumulation amount, and its value affects the prediction accuracy of the nitrogen requirement model.

[0172] In detail, the nitrogen requirement model is a mathematical model established based on the light-nitrogen coupling relationship, which is used to calculate the target nitrogen accumulation amount and nitrogen application amount required for the growth of hybrid rice according to the compensation light transmittance.

[0173] In detail, the growth stage is a different period of hybrid rice growth and development, and in the present application, it mainly involves key growth stages such as the tillering stage and the heading stage, and the demand for nitrogen is different in each stage.

[0174] In detail, the correction report is a summary document about the adjustment process and effect of the lag compensation relationship generated at the end of the heading stage, which is used to record the model optimization process and provide data reference.

[0175] Further, leaf nitrogen accumulation data measured after each nitrogen application is extracted from the monitoring results of step S4, and the preset nitrogen accumulation threshold value corresponding to the growth stage is called. The preset threshold value is determined according to the historical high yield data of the rice variety, for example, the threshold value at the tillering peak stage is 25-30 g / m 2 , and the threshold value at the heading stage is 30-35 g / m 2 .

[0176] Further, the dynamic deviation of each monitored leaf nitrogen accumulation and the preset threshold value is calculated, for example, if the monitored value is 28 g / m 2 , and the threshold value is 30 g / m 2 , then the dynamic deviation is -2 g / m 2 .

[0177] Further, the dynamic deviation data of continuous multiple times (such as 3 times) in time sequence is arranged, the positive and negative trend is analyzed, and whether the nitrogen accumulation is continuously higher or lower than the threshold value is judged: when the dynamic deviation is positive for 3 times in a row, it indicates that the nitrogen demand predicted by the model is too high due to the current lag compensation parameter, and the value of the lag compensation parameter needs to be reduced by 1 day each time, but not less than 1 day, for example, the original parameter is 5 days, and the adjustment is 4 days; when the dynamic deviation is negative for 3 times in a row, it indicates that the nitrogen demand predicted by the model is too low, and the value of the lag compensation parameter needs to be increased by 1 day each time, but not more than 10 days, for example, the original parameter is 5 days, and the adjustment is 6 days.

[0178] Further, the lag compensation parameter represents the physiological response lag time of the effect of light transmittance on nitrogen accumulation. When the nitrogen accumulation is continuously higher than the threshold value, it indicates that the effect of light transmittance change on nitrogen demand is faster than the model preset, so the lag time is shortened; otherwise, the lag time is prolonged to match the actual physiological response.

[0179] Further, at the end of the current growth stage (2-3 days before the start of the next growth stage), the corrected lag compensation parameter is synchronized to the parameter library of the nitrogen demand model. For example, before the heading stage starts, the corrected parameter (such as adjusted from 5 days to 4 days) at the tillering peak stage is input into the model.

[0180] Further, the nitrogen demand model automatically updates the calculation logic of compensating light transmittance after receiving the new parameter.

[0181] Further, the report content includes: recording the adjustment time, the value before adjustment, the value after adjustment, and the adjustment reason (such as continuous deviation trend) of the lag compensation parameter before the start of each growth stage; and summarizing the dynamic deviation distribution of all leaf nitrogen accumulation monitoring data during the heading stage, including the average deviation, the maximum deviation, and the positive and negative frequency of the deviation.

[0182] Further, within 24 hours after the end of the heading stage, data is automatically extracted from the database and a PDF format report is generated, stored on the system server and pushed to the user terminal.

[0183] In summary, this step of dynamic deviation analysis and lag compensation parameter modification solves the prediction deviation problem caused by the fixed physiological response lag time of the nitrogen requirement model. Real-time feedback adjustment of the model parameters according to the nitrogen accumulation amount enables the model to adapt to the light-nitrogen response characteristics of hybrid rice at different growth stages and environmental conditions, avoids the deviation of nitrogen application amount caused by inaccurate lag compensation of the model, improves the accuracy of nitrogen requirement prediction and the adaptability of the control system, and ultimately realizes the continuous optimization of light-nitrogen coupling control efficiency.

[0184] As shown in Figure 2 is a functional module diagram of the hybrid rice canopy light-nitrogen coupling high-yield control system in a middle-low yield field according to an embodiment of the present application.

[0185] The hybrid rice canopy light-nitrogen coupling high-yield control system 100 in a middle-low yield field according to the present application can be installed in an electronic device. According to the functions implemented, the hybrid rice canopy light-nitrogen coupling high-yield control system 100 can include a real-time light transmittance acquisition module 101, a nitrogen requirement model construction module 102, a nitrogen application timing instruction generation module 103, a leaf nitrogen accumulation amount monitoring module 104, and a lag compensation relationship modification module 105. The modules according to the present application can also be referred to as units, which refer to a series of computer program segments that can be executed by an electronic device processor and can complete fixed functions, and are stored in the memory of the electronic device.

[0186] In this embodiment, the functions of each module / unit are as follows:

[0187] The real-time light transmittance acquisition module 101 is used to acquire the real-time light transmittance of the hybrid rice canopy during the key growth periods from the tillering peak period to the heading period.

[0188] The nitrogen requirement model construction module 102 is used to construct a nitrogen requirement model based on the lag compensation relationship between the real-time light transmittance and the leaf nitrogen accumulation amount, and output a target nitrogen application amount.

[0189] The nitrogen application timing instruction generation module 103 is used to generate a nitrogen application timing instruction according to the target nitrogen application amount, the nitrogen application timing instruction including a fertilization time point and a duration, and the interval between adjacent fertilization times being dynamically adjusted by the light transmittance change rate.

[0190] The leaf nitrogen accumulation amount monitoring module 104 is used to execute the nitrogen application timing instruction and simultaneously monitor the leaf nitrogen accumulation amount of the hybrid rice.

[0191] The hysteresis compensation relationship correction module 105 is configured to correct the hysteresis compensation relationship of the nitrogen requirement model before the next growth stage starts based on the dynamic deviation of the leaf nitrogen accumulation amount from the preset nitrogen accumulation amount threshold.

[0192] In several embodiments provided in the present application, it should be understood that the disclosed method and system can be implemented in other ways. For example, the system embodiments described above are only illustrative, for example, the division of the modules is only a logical function division, and actual implementation can have another division manner.

[0193] The modules described as separate components can or can not be physically separated, and the components displayed as modules can or can not be physical units, that is, they can be located in one place or distributed to multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment.

[0194] In addition, the functional modules in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of hardware plus software function modules.

[0195] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application.

[0196] The embodiments of the present application can acquire and process related data based on artificial intelligence technology. Among them, artificial intelligence is to use digital computers or machine controlled by digital computers to simulate, extend and expand human intelligence, perceive environment, acquire knowledge and use knowledge to obtain the best results.

[0197] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields, characterized in that, The method includes: S1. During the critical growth period from the peak tillering stage to the heading stage, obtain the real-time light transmittance of the hybrid rice canopy; S2. Based on the lag compensation relationship between the real-time light transmittance and the nitrogen accumulation in the leaves, a nitrogen demand model is constructed and the target nitrogen application rate is output; S3. Generate a nitrogen application timing instruction based on the target nitrogen application amount. The nitrogen application timing instruction includes the fertilization time point and duration, and the time interval between adjacent fertilizations is dynamically adjusted by the transmittance change rate. S4. Execute the nitrogen application timing command and simultaneously monitor the nitrogen accumulation in the leaves of hybrid rice; S5. Based on the dynamic deviation between the nitrogen accumulation in the leaves and the preset nitrogen accumulation threshold, the lag compensation relationship of the nitrogen demand model is corrected before the start of the next growth stage.

2. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 1, characterized in that, The method of obtaining the real-time transmittance of the hybrid rice canopy includes: An array of light intensity sensors was deployed above the canopy of hybrid rice to collect the intensity of incident solar radiation. A transmission light sensor array was deployed symmetrically below the canopy of hybrid rice to collect the intensity of transmitted light penetrating the canopy. Calculate the instantaneous transmittance ratio based on the incident light intensity and the transmitted light intensity; The instantaneous transmittance ratio is subjected to time-series filtering to obtain the real-time transmittance of the hybrid rice canopy.

3. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 1, characterized in that, The lag compensation relationship between the real-time transmittance and leaf nitrogen accumulation includes: Obtain historical light transmittance and corresponding measured values ​​of nitrogen accumulation in leaves during historical growth periods; The historical light transmittance is shifted backward by a preset number of days to align with the measured value of nitrogen accumulation in the leaves. Calculate the correlation coefficient between the historical light transmittance after translation and the nitrogen accumulation of the leaf, and iteratively adjust the number of translation days until the correlation coefficient reaches its maximum value; The number of days of translation corresponding to the maximum correlation coefficient is used as the lag compensation parameter.

4. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 3, characterized in that, The construction of the nitrogen demand model and the output of the target nitrogen application rate include: The real-time transmittance is shifted according to the hysteresis compensation parameter to obtain the compensated transmittance of the hybrid rice canopy. Establish a linear regression model between the compensated transmittance and the target nitrogen accumulation; N target =k·T comp +N soil +N residual -N loss Among them, T comp It is the compensation transmittance, k is the photo-nitrogen conversion efficiency factor, and N is the nitrogen conversion efficiency factor. target It is the target nitrogen accumulation, N soil It is the soil available nitrogen content measured before sowing, N residual It is residual nitrogen that was not utilized in the early stages, N loss This is the amount of ammonia lost through volatilization; Input the current light transmittance into the linear regression model to output the target nitrogen application rate.

5. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 1, characterized in that, The step of generating nitrogen application timing instructions based on the target nitrogen application amount includes: The target nitrogen application rate is broken down into the total amount of several nitrogen application operations; Calculate the absolute value of the rate of change of transmittance at adjacent time points; When the absolute value of the rate of change of light transmittance increases, the time interval between adjacent fertilization applications should be shortened. When the absolute value of the rate of change of light transmittance decreases, the time interval between adjacent fertilization applications is extended. A set of fertilization time points for hybrid rice is generated based on dynamically adjusted time intervals, and an equal amount of nitrogen application is allocated to each fertilization time point in the set.

6. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 1, characterized in that, The synchronous monitoring of nitrogen accumulation in hybrid rice leaves includes: After each nitrogen application, functional leaf samples were collected from the middle of the hybrid rice canopy. The functional leaf sample was decolorized and dried to obtain dry matter; The nitrogen content of the dry matter was determined by the micro Kjeldahl method, and the nitrogen accumulation per unit area of ​​the leaf was calculated in combination with the sample leaf area.

7. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 6, characterized in that, The monitoring and verification of nitrogen accumulation in the leaves includes: When the coefficient of variation of continuously monitored leaf nitrogen accumulation exceeds a preset variation threshold, a resampling mechanism is triggered. Backup leaf samples were recollected at the same location in the hybrid rice canopy layer. If the difference between the measured value of the backup leaf sample and the original sample exceeds the tolerance range, laboratory arbitration testing is activated, and the leaf nitrogen accumulation record is updated with the arbitration test result.

8. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 1, characterized in that, The steps for determining the duration of the nitrogen application timing command are as follows: Get the current soil infiltration rate category: When the soil is clayey, extend the duration of nitrogen application. When the soil is sandy, shorten the duration of nitrogen application.

9. The method for high-yield regulation of hybrid rice canopy light-nitrogen coupling in low- and medium-yield fields as described in claim 3, characterized in that, The process of providing feedback and correction to the lag compensation relationship of the nitrogen demand model before the start of the next reproductive stage includes: Calculate the dynamic deviation between the nitrogen accumulation in the leaves and the preset nitrogen accumulation threshold; When the dynamic deviation remains positive, decrease the daily value of the hysteresis compensation parameter; When the dynamic deviation remains negative, increase the day value of the hysteresis compensation parameter; The corrected lag compensation parameters are then input into the nitrogen demand model for the next reproductive stage. A report on the correction of the lag compensation relationship is generated at the end of the heading period.

10. A high-yield regulation system for canopy light-nitrogen coupling in low- and medium-yield hybrid rice fields, characterized in that, The system includes: The real-time transmittance acquisition module is used to acquire the real-time transmittance of the hybrid rice canopy during the critical growth period from the tillering stage to the heading stage. The nitrogen demand model construction module is used to construct a nitrogen demand model and output the target nitrogen application rate based on the lag compensation relationship between the real-time light transmittance and the nitrogen accumulation in the leaves. The nitrogen application timing instruction generation module is used to generate nitrogen application timing instructions based on the target nitrogen application amount. The nitrogen application timing instructions include the fertilization time point and duration, and the time interval between adjacent fertilizations is dynamically adjusted by the transmittance change rate. The leaf nitrogen accumulation monitoring module is used to execute the nitrogen application timing command and simultaneously monitor the leaf nitrogen accumulation of hybrid rice. The lag compensation relationship correction module is used to correct the lag compensation relationship of the nitrogen demand model before the start of the next growth stage based on the dynamic deviation between the nitrogen accumulation of the leaves and the preset nitrogen accumulation threshold.

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