A method for evaluating crop nutrient efficiency based on polar coordinates

Abstract

The present invention belongs to the technical field of crop planting, and particularly relates to a method for evaluating crop nutrient efficiency based on polar coordinates. Taking the yield of the variety to be tested in the nutrient-deficient plot as the abscissa, the yield in the normal plot as the ordinate, and the average yield of several control varieties as the origin, a polar coordinate system is established; based on the established polar coordinate system, the polar coordinates of the variety to be tested are obtained; the projection difference is calculated using the polar coordinate data of the variety to be tested, and the nutrient efficiency of the variety to be tested is evaluated using this projection difference. The method provided by the present invention can accurately and quickly evaluate the crop nutrient efficiency, does not require chemical component detection, has low cost and is easy to operate, and the results at different locations are comparable.

Description

Technical Field

[0001] The present invention belongs to the technical field of crop planting, and particularly relates to a method for evaluating crop nutrient efficiency based on polar coordinates. Background Art

[0002] The application of chemical synthetic fertilizers has greatly increased crop yields and ensured global food security. Cultivating crop varieties with high nutrient efficiency is an important measure to improve crop nutrient use efficiency, which is inseparable from the evaluation technology and calculation methods of crop nutrient efficiency. At present, indicators such as partial factor productivity of chemical fertilizers, agronomic utilization rate of chemical fertilizers, fertilizer recovery rate, and nutrient physiological utilization rate are mostly used to measure crop nutrient efficiency. However, these methods have the following defects respectively:

[0003] (1) Partial factor productivity of chemical fertilizers

[0004] Partial factor productivity of chemical fertilizers = Crop yield / Chemical fertilizer application rate

[0005] Obviously, this indicator is significantly affected by soil factors. There are huge differences in the nutrient supply capacity (nutrient availability) of different regions and different soils, resulting in poor reliability of its cross-regional and horizontal comparisons. Specifically, in areas with fertile soil, the crop nutrient efficiency is underestimated; while in areas with poor soil, the crop nutrient efficiency is overestimated. Therefore, the partial factor productivity of chemical fertilizers is limited by the soil and climate conditions of the test sites, and the comparability of results at different sites is poor.

[0006] (2) Agronomic utilization rate of chemical fertilizers

[0007] Agronomic utilization rate of chemical fertilizers = (Yield in fertilized plot - Yield in non-fertilized plot) / Fertilizer application rate

[0008] This indicator introduces the yield in the non-fertilized plot as a control, which avoids the influence of soil factors to a certain extent, but ignores the genotypic differences in the response of crops to nutrient availability, and there is still a lack of reliable reference for comparisons between different regions and different varieties.

[0009] (3) Fertilizer recovery rate and nutrient physiological utilization rate

[0010] Fertilizer recovery rate = (Nutrient accumulation in the harvested organs of crops in the fertilized plot - Nutrient accumulation in the harvested organs of crops in the non-fertilized plot) / Fertilizer application rate

[0011] Nutrient physiological utilization rate = Biomass of the harvested organs of crops / Nutrient accumulation of crops

[0012] The fertilizer recovery rate and nutrient physiological utilization rate measure the nutrient efficiency of crops from the perspectives of nutrient absorption and assimilation respectively. However, the calculation method relies on chemical analysis, and the samples must go through multiple processing steps such as drying, pulverizing, digestion, and chemical stoichiometry (such as Kjeldahl nitrogen determination, potassium measurement by flame combustion method, and phosphorus measurement by vanadium molybdate yellow colorimetry) to obtain nutrient content data, which is costly and time-consuming. Summary of the Invention

[0013] In view of the above technical problems, based on polar coordinates and vector analysis, the present invention proposes a method for evaluating the nutrient efficiency of crops based on polar coordinates, which can accurately and quickly evaluate the nutrient efficiency of crops, does not require chemical composition detection, has low cost and is easy to operate, and the results at different locations are comparable.

[0014] The specific technical solution provided by the present invention is as follows:

[0015] The present invention provides a method for evaluating the nutrient efficiency of crops based on polar coordinates, including the following steps:

[0016] Taking the yield of the variety to be tested in the nutrient-deficient plot as the abscissa, the yield in the normal plot as the ordinate, and the average yield of several control varieties as the origin, establish a polar coordinate system;

[0017] Based on the established polar coordinate system, obtain the polar coordinates of the variety to be tested;

[0018] Calculate the projection difference using the polar coordinate data of the variety to be tested, and evaluate the nutrient efficiency of the variety to be tested using this projection difference.

[0019] As a preferred embodiment of the present invention, the polar coordinate data of the variety to be tested includes a feature vector with a radius of r and a polar angle of θ0.

[0020] As a preferred embodiment of the present invention, the polar coordinates of the jth variety to be tested are:

[0021]

[0022]

[0023] where r j is the radius of the jth variety to be tested, θ j is the polar angle of the jth variety to be tested, Tj N0 is the yield of the jth variety to be tested in the nutrient-deficient plot, Tj N225 is the yield of the jth variety to be tested in the normal plot, Ci N0 is the yield of the ith control variety in the nutrient-deficient plot, Ci N225 is the yield of the ith control variety in the normal plot, and n is the number of control varieties.

[0024] As a preferred embodiment of the present invention, the calculation formula for the projection difference is as follows:

[0025] PD = sinθ0 - cosθ0 * r

[0026] Wherein, PD is the projection difference, θ0 is the polar angle in the polar coordinate data of the variety to be measured, 0 ≤ θ0 < 360°, and r is the radius in the polar coordinate data of the variety to be measured.

[0027] As a preferred embodiment of the present invention, the standard for evaluating the crop nutrient efficiency using the projection difference is as follows:

[0028] When PD < 0, the nutrient efficiency of the variety to be measured is lower than that of the control variety;

[0029] When PD = 0, the nutrient efficiency of the variety to be measured is equal to that of the control variety;

[0030] When PD > 0, the nutrient efficiency of the variety to be measured is higher than that of the control variety.

[0031] As a preferred embodiment of the present invention, the yield potential of the variety to be measured is evaluated using the polar angle of the polar coordinate data of the variety to be measured as an index.

[0032] More preferably, the evaluation standard for evaluating the yield potential of the variety to be measured using the polar angle is as follows:

[0033] When 0 < θ0 < 180°, the yield potential of the variety to be measured is higher than that of the control variety;

[0034] When 180° < θ0 < 360°, the yield potential of the variety to be measured is lower than that of the control variety.

[0035] As a preferred embodiment of the present invention, the nutrient efficiency and yield potential of the variety to be measured are comprehensively evaluated using the polar angle of the polar coordinate data of the variety to be measured and the projection difference as indexes.

[0036] More preferably, the evaluation standard for comprehensively evaluating the nutrient efficiency and yield potential of the variety to be measured is as follows:

[0037] When PD > 0 and 45° < θ0 < 180°, both the nutrient efficiency and yield potential of the variety to be measured are higher than those of the control variety;

[0038] When PD > 0 and 180° < θ0 < 225°, the nutrient efficiency of the variety to be measured is higher than that of the control variety, but the yield potential is lower than that of the control variety;

[0039] When PD < 0 and 0° < θ0 < 45°, the nutrient efficiency of the variety to be measured is lower than that of the control variety, but the yield potential is higher than that of the control variety;

[0040] When PD < 0 and 225° < θ0 < 360°, the nutrient efficiency and yield potential of the variety to be tested are both lower than those of the control variety.

[0041] As a preferred embodiment of the present invention, the nutrient efficiency of a crop refers to the absorption and utilization of nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium, and zinc by the crop.

[0042] As a preferred embodiment of the present invention, the crops include but are not limited to corn, wheat, rice, soybeans, or fruits and vegetables.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The method provided by the present invention uses polar coordinates and vector analysis to establish a method for evaluating the nutrient efficiency of crops that does not rely on chemical component detection from the perspective of crop response to fertilizer input, and has the advantages of low cost, short cycle, easy operation, and strong comparability.

[0045] The method provided by the present invention can be used to evaluate the nutrient efficiency of crops for macronutrients such as nitrogen, phosphorus, and potassium, and is applicable to crops including but not limited to corn, rice, wheat, or fruits and vegetables. Description of the Drawings

[0046] Figure 1 is a method for evaluating the nutrient efficiency and yield potential of crops. Detailed Embodiments

[0047] The exemplary embodiments of the present disclosure will be described in more detail below. Although the exemplary embodiments of the present disclosure are shown below, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0048] The prior art mostly uses indicators such as partial factor productivity of chemical fertilizers, agronomic utilization rate of chemical fertilizers, fertilizer recovery rate, and nutrient physiological utilization rate to measure the nutrient efficiency of crops. However, these methods have the following defects respectively:

[0049] The partial factor productivity of chemical fertilizers is limited by the soil and climate conditions of the test site, and the comparability of results at different sites is poor; the agronomic utilization rate of chemical fertilizers ignores the genotypic differences in the response of crops to nutrient availability, and there is still a lack of reliable reference for comparison between different regions and different varieties; the calculation methods of fertilizer recovery rate and nutrient physiological utilization rate rely on chemical analysis, and samples must go through multiple processing steps such as drying, grinding, digestion, and chemical stoichiometry to obtain nutrient content data, with high cost and long cycle.

[0050] Based on this, the present invention provides a method for evaluating crop nutrient efficiency based on polar coordinates, comprising the following steps:

[0051] Taking the yield of the variety to be tested in the nutrient-deficient plot as the abscissa, the yield in the normal plot as the ordinate, and the average yield of several control varieties as the origin, a polar coordinate system is established;

[0052] Based on the established polar coordinate system, the polar coordinates of the variety to be tested are obtained;

[0053] The projection difference is calculated using the polar coordinate data of the variety to be tested, and the nutrient efficiency of the variety to be tested is evaluated using this projection difference.

[0054] Using the evaluation method provided by the present invention, accurate and rapid evaluation of crop nutrient efficiency can be achieved. There is no need for chemical composition detection, the cost is low, it is easy to operate, and the results at different locations are comparable.

[0055] The following is illustrated with specific embodiments.

[0056] Evaluating crop nutrient efficiency based on polar coordinates includes the following steps:

[0057] (1) Taking the nitrogen nutrient efficiency of corn as an example.

[0058] The experiment is carried out on a nitrogen-deficient plot where nitrogen fertilizer has not been applied for more than five consecutive years and a normal plot with a nitrogen fertilizer application rate of 225 kg N / ha (i.e., the internationally recognized safe application upper limit). The experimental materials are m varieties to be tested (labeled as T1, T2, T3... Tm) and n control varieties (labeled as C1, C2, C3... Cn). For other agronomic measures and links such as control varieties and their quantities, tillage methods, planting areas, planting densities, phosphorus and potassium fertilizer application rates, pest, disease and weed management, harvesting and storage, etc., refer to the "Measures for the Approval of Main Crop Varieties" revised in 2022.

[0059] (2) In the nitrogen-deficient plot, the yields of the m varieties to be tested are T1 N0 , T2 N0 , T3 N0 ... Tm N0 , and the yields of the n control varieties are C1 N0 , C2 N0 , C3 N0 ... Cn N0 ; in the normal plot, the yields of the m varieties to be tested are T1 N225 , T2 N225 , T3 N225 ... Tm N225 , and the yields of the n control varieties are C1 N225 , C2 N225 , C3N225 ……Cn N225 。

[0060] (3) Establish a polar coordinate system with the yield of the variety to be tested in the nitrogen-deficient plot as the abscissa (x-axis), the yield in the normal plot as the ordinate (y-axis), and the average yield of n control varieties as the origin (also known as the pole). The polar coordinates of the j-th variety to be tested are:

[0061]

[0062]

[0063] At this time, each variety to be tested has a characteristic vector with a radius of r and a polar angle of θ0, where i represents the i-th control variety.

[0064] Nutrient efficiency is expressed by the increase in yield from the nitrogen-deficient plot to the normal plot. If the increase of the tested variety is greater than that of the control variety, it is said that the nutrient efficiency of the tested variety is higher than that of the control variety; if the increase of the tested variety is less than that of the control variety, it is said that the nutrient efficiency of the tested variety is lower than that of the control variety.

[0065] Projection differential (PD) can be used to measure the nutrient efficiency of crops, and the calculation method is:

[0066] PD = sinθ0 - cosθ0 * r

[0067] Among them, θ0 is the polar angle in the polar coordinates of the crop, r is the radius in the polar coordinates of the crop, and the value range of θ0 is [0, 360°), that is, 0 ≤ θ0 < 360°.

[0068] (4) Evaluation of crop nutrient efficiency and yield potential, see Figure 1

[0069] ① Evaluate the nutrient efficiency of crops using PD

[0070] When PD < 0, the nutrient efficiency of the variety to be tested is lower than that of the control variety;

[0071] When PD = 0, the nutrient efficiency of the variety to be tested is equal to that of the control variety;

[0072] When PD > 0, the nutrient efficiency of the variety to be tested is higher than that of the control variety.

[0073] ② The polar angle θ0 can be used to evaluate the yield potential of crop varieties:

[0074] When 0 < θ0 < 180°, the yield potential of the variety to be tested is higher than that of the control variety, that is, there is hope to obtain a higher yield than the control variety under normal planting management;

[0075] When 180° < θ0 < 360°, the yield potential of the variety to be tested is lower than that of the control variety.

[0076] ③ Combine PD with θ0 to comprehensively evaluate the crop yield potential and nutrient efficiency:

[0077] When PD > 0 and 45° < θ0 < 180°, both the nutrient efficiency and yield potential of the variety to be tested are higher than those of the control variety;

[0078] When PD > 0 and 180° < θ0 < 225°, the nutrient efficiency of the variety to be tested is higher than that of the control variety, but the yield potential is lower than that of the control variety;

[0079] When PD < 0 and 0° < θ0 < 45°, the nutrient efficiency of the variety to be tested is lower than that of the control variety, but the yield potential is higher than that of the control variety;

[0080] When PD < 0 and 225° < θ0 < 360°, both the nutrient efficiency and yield potential of the variety to be tested are lower than those of the control variety.

[0081] The method provided by the present invention can evaluate the crop nutrient efficiency of macronutrients such as nitrogen, phosphorus, and potassium, and is applicable to crops including but not limited to corn, rice, wheat, or fruits and vegetables.

[0082] The following is illustrated with specific application examples.

[0083] Experimental design: 5 varieties to be tested and 1 control variety. For both the varieties to be tested and the control variety, two groups with nitrogen application rates of 0 and 225 kg N / ha are set, and the experiment is carried out for nine years in a long-term fixed-location manner. At the physiological maturity stage (harvest stage), the grain yield, grain nitrogen concentration, straw biomass, and straw nitrogen concentration are measured, and the partial factor productivity of applied nitrogen, agronomic nitrogen use efficiency, nitrogen recovery efficiency, nitrogen physiological efficiency, PD, and θ0 are calculated. The situations of the varieties to be tested and the control variety are shown in Table 1. The measurement results at the harvest stage are shown in Table 2. The calculation results of relevant evaluation indexes are shown in Table 3.

[0084] Table 1 Variety numbers, names, and breeding years

[0085]

[0086] Table 2 Grain yield, grain nitrogen concentration, straw biomass, and straw nitrogen concentration at physiological maturity

[0087]

[0088]

[0089] Table 3 Partial factor productivity of applied nitrogen, agronomic nitrogen use efficiency, nitrogen recovery efficiency, nitrogen physiological efficiency, PD, and θ0

[0090]

[0091] Correlation analysis shows that the Pearson coefficients of PD with partial factor productivity of nitrogen fertilizer, agronomic nitrogen use efficiency, nitrogen recovery rate, and physiological nitrogen use efficiency are 0.9887, 0.9999, 0.8570, and 0.9042 respectively, and all reach an extremely significant level, indicating that the projection difference PD can be well used to evaluate crop nutrient efficiency. According to the discrimination criteria provided by the present invention, the nutrient efficiency and yield potential of T1, T2, and T3 are lower than those of the control variety; the nutrient efficiency of T4 is lower than that of the control variety, but the yield potential is higher than that of the control variety; the nutrient efficiency and yield potential of T5 are higher than those of the control variety. Therefore, T5 can be used as a potential breeding variety with high nutrient efficiency.

[0092] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for evaluating crop nutrient efficiency based on polar coordinates, characterized in that, Including the following steps: Taking the yield of the variety to be tested in the nutrient-deficient plot as the abscissa, the yield in the normal plot as the ordinate, and the average yield of several control varieties as the origin, establish a polar coordinate system; Based on the established polar coordinate system, obtain the polar coordinates of the variety to be tested; Calculate the projection difference using the polar coordinate data of the variety to be tested, and use this projection difference to evaluate the nutrient efficiency of the variety to be tested; The polar coordinate data of the variety to be tested includes eigenvectors with a radius of r and a polar angle of θ0. The polar coordinates of the j-th variety to be tested are: where r j is the radius of the j-th variety to be measured, θ j is the polar angle of the j-th variety to be measured, Tj N0 is the yield of the j-th variety to be measured in the nutrient-deficient plot, Tj N225 is the yield of the j-th variety to be measured in the normal plot, Ci N0 is the yield of the i-th control variety in the nutrient-deficient plot, Ci N225 is the yield of the i-th control variety in the normal plot, and n is the number of control varieties; The calculation formula for the projection difference is: PD = (sinθ0 - cosθ0) * r Where PD is the projection difference, θ0 is the polar angle in the polar coordinate data of the variety to be tested, 0 ≤ θ0 < 360°, and r is the radius in the polar coordinate data of the variety to be tested.

2. The method for evaluating crop nutrient efficiency based on polar coordinates according to claim 1, characterized in that, The criteria for evaluating the nutrient efficiency of the variety to be tested using the projection difference are: When PD < 0, the nutrient efficiency of the variety to be tested is lower than that of the control variety; When PD = 0, the nutrient efficiency of the variety to be tested is equal to that of the control variety; When PD > 0, the nutrient efficiency of the variety to be tested is higher than that of the control variety.

3. The method for evaluating crop nutrient efficiency based on polar coordinates according to claim 1, wherein Taking the polar angle of the polar coordinate data of the variety to be tested as an index to evaluate the yield potential of the variety to be tested.

4. The method for evaluating crop nutrient efficiency based on polar coordinates according to claim 3, wherein The evaluation criteria for evaluating the yield potential of the variety to be tested by the polar angle are: When 0 < θ0 < 180°, the yield potential of the variety to be tested is higher than that of the control variety; When 180° < θ0 < 360°, the yield potential of the variety to be tested is lower than that of the control variety.

5. The method for evaluating crop nutrient efficiency based on polar coordinates according to claim 1, wherein Taking the polar angle of the polar coordinate data of the variety to be tested and the projection difference as indices to comprehensively evaluate the nutrient efficiency and yield potential of the variety to be tested.

6. The method for evaluating crop nutrient efficiency based on polar coordinates according to claim 5, wherein, The evaluation criteria for comprehensively evaluating the nutrient efficiency and yield potential of the variety to be tested are: When PD > 0 and 45° < θ0 < 180°, both the nutrient efficiency and yield potential of the variety to be tested are higher than those of the control variety; When PD > 0 and 180° < θ0 < 225°, the nutrient efficiency of the variety to be tested is higher than that of the control variety, but the yield potential is lower than that of the control variety; When PD < 0 and 0° < θ0 < 45°, the nutrient efficiency of the variety to be tested is lower than that of the control variety, but the yield potential is higher than that of the control variety; When PD < 0 and 225° < θ0 < 360°, both the nutrient efficiency and yield potential of the variety to be tested are lower than those of the control variety.

7. The method for evaluating crop nutrient efficiency based on polar coordinates according to claim 1, characterized in that, The nutrient efficiency refers to the utilization efficiency of crops for nitrogen, phosphorus, and potassium.

8. The method for evaluating crop nutrient efficiency based on polar coordinates according to claim 1, characterized in that, The crops are selected from corn, wheat, rice, soybeans, or fruit and vegetable plants.

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