Method for identifying drought resistance of corn variety based on comprehensive weight

Abstract

The invention belongs to the technical field of plant drought resistance identification, and discloses a method for identifying the drought resistance of corn varieties based on comprehensive weights. According to the method, the yield, the water utilization efficiency and a plurality of physiological and biochemical indexes in the corn growth period are combined, through a membership function method, principal component analysis and D value synthesis, the drought resistance of different varieties of corn under film mulching and non-film mulching treatment is systematically evaluated, and a drought-resistant high-yield and high-efficiency prediction model is further established through stepwise regression analysis; and a basis is provided for later large-scale variety screening. The regression equation of the model for predicting the drought resistance, high yield and high efficiency of the corn is as follows: YWD =-2.878 + 0.120 DIX1 + 0.096 DIX2 + 0.278 DIX3 + 0.897 DIX4 + 0.713 DIX6 + 0.570 DIX7 + 0.127 DIX14 + 1.196 DIX16 + 0.141 DIX18, R2 is 0.97, and the fitting effect is better.

Description

Technical Field

[0001] This invention belongs to the field of plant drought resistance identification technology, and relates to a method for identifying the drought resistance of maize varieties based on comprehensive weighting. Background Technology

[0002] Maize, an annual herbaceous plant belonging to the genus *Zea* of the Poaceae family, serves multiple purposes as a food, feed, and industrial raw material, making it an important economic crop. As a water-loving crop, its growth and development are highly sensitive to water, requiring a stable water supply from the seedling stage to the grain-filling stage. Water deficiency directly affects its normal growth process. In the dryland farming areas of Northwest China, agricultural production relies on natural rainfall, exhibiting rainfed agriculture characteristics. Drought is the main abiotic stress factor affecting maize yield and quality in this region. When maize suffers from drought stress, it exhibits a series of physiological and growth abnormalities, such as slow growth, leaf wilting, prolonged flowering period, decreased photosynthetic efficiency, and reduced seed setting rate, ultimately leading to quality deterioration, sharp yield reduction, or even crop failure.

[0003] Currently, the pace of corn variety renewal is rapid, with a significant increase in the number of varieties. However, the selection system for drought-resistant varieties in dryland areas is still imperfect, lacking specificity and making it difficult for farmers to accurately select varieties with excellent drought resistance. This results in poor corn quality and low yields in dryland areas. Existing technologies have conducted extensive research on corn drought resistance, proposing various methods for identifying drought resistance and related evaluation indicators. These methods and indicators reflect the drought resistance characteristics of corn varieties from different dimensions. However, plant drought resistance is a complex and multifaceted trait regulated by multiple physiological and biochemical mechanisms. Influenced by factors such as geographical environment, crop type, and drought resistance technology models, the performance and underlying mechanisms of drought resistance vary significantly across different research systems. Existing identification methods and indicators cannot form a unified and universally applicable evaluation standard. Therefore, developing a comprehensive, multi-indicator, and multi-method systematic method for analyzing corn variety drought resistance is of great significance for improving the accuracy and reliability of drought resistance evaluation results and guiding the breeding and cultivation management practices of drought-resistant corn varieties in dryland areas. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for identifying the drought resistance of maize varieties based on comprehensive weighting. This invention combines yield, water use efficiency, and multiple physiological and biochemical indicators of maize growth stages. Through membership function method, principal component analysis, and comprehensive D-value, it systematically evaluates the differences in drought resistance between mulched and unmulched maize treatments. Furthermore, it establishes a predictive model for the drought resistance, high yield, and high efficiency of varieties through stepwise regression analysis, providing a basis for large-scale variety screening in the later stages. The regression equation for the predictive model of drought resistance, high yield, and high efficiency of maize in this invention is: YWD=-2.878+0.120DIX1+0.096DIX2+0.278DIX3+0.897DIX4+0.713DIX6+0.570DIX7+0.127DIX14+1.196DIX16+0.141DIX18. The R-squared value of this regression equation is... 2 The value is 0.97, indicating a good fitting effect.

[0005] On the one hand, this invention provides a method for identifying drought resistance of maize varieties based on comprehensive weighting, comprising: Emergence rate, dry weight, SPAD value, plant height, stem diameter, and ear diameter were measured during the maize growth period. During the corn harvest period, yield, nitrogen accumulation, and tip barrenness length are measured. Soil moisture content was tested before corn planting and during corn harvest. Based on the data obtained from the test, the water use efficiency (WUE) and drought resistance comprehensive evaluation (D) value are calculated. The yield drought resistance index (DIY) and the water use efficiency drought resistance index (DIWUE) are calculated according to the drought resistance index calculation method. Then, the comprehensive value of drought resistance, high yield and high efficiency is calculated. The larger the comprehensive value of drought resistance, high yield and high efficiency, the stronger the drought resistance of the maize variety. The formula for calculating the comprehensive value of drought resistance, high yield, and high efficiency is: YWD=[(DIY / DIY)] i )+(DIWUE / DIWUE i )+(D / D i )] / 3; The DIY i The DIWUE is the average yield drought resistance index of all tested varieties. i D represents the average water use efficiency drought resistance index of all tested varieties. i The average value of the drought resistance comprehensive evaluation (D value) for all tested varieties.

[0006] Furthermore, the dry matter weight refers to the dry matter weight at the ten-leaf stage, the dry matter weight at the silking stage, and the dry matter weight at the maturity stage; The SPAD values ​​are the SPAD values ​​at the six-leaf stage, ten-leaf stage, silking stage, and grouting stage. The plant height mentioned is the plant height during the silking stage; The stem diameter refers to the stem diameter at the ten-leaf stage and the stem diameter at the silk-spraying stage.

[0007] Furthermore, the formula for calculating the comprehensive drought resistance evaluation D value is as follows: ; The U(X) i ) represents the membership function value of the i-th indicator, which consists of dry matter content, SPAD value, plant height, stem diameter, ear diameter, nitrogen accumulation, and tip barrenness length, where n is the number of indicators; The W f The weights of the principal component analysis factors.

[0008] Furthermore, the U(X) i The calculation method for ) is as follows: ; The DIX i Let DIX be the drought resistance index of the i-th indicator. imin The minimum value of the i-th indicator, the drought resistance index, is defined as DIX. imax Let n be the maximum value of the drought resistance index of the i-th indicator, where n is the number of indicators.

[0009] Furthermore, the W f The calculation method is as follows: ; The P f Let m be the contribution rate of each principal component analysis factor, and m be the number of principal component analysis factors.

[0010] Furthermore, the drought resistance index is calculated as follows: DI = (X d / X w )×(X d / X di ); The X d The measured value of the index is the value without coating treatment, and the X is the value of the index measured without coating treatment. w The measured value of the index under the coating treatment, namely X di The values ​​represent the average values ​​of the tested varieties without film covering.

[0011] Furthermore, the formula for calculating the water use efficiency is: WUE = Y / ET; Y represents yield, and ET represents crop water consumption.

[0012] Furthermore, the formula for calculating ET is: ET = M1 + P + M2; M1 represents the soil water storage before sowing, P represents the rainfall during the growing season, and M2 represents the soil water storage at harvest.

[0013] Furthermore, the formula for calculating the nitrogen accumulation is: Nitrogen accumulation = Dry weight of each aboveground organ × Nitrogen content of each organ.

[0014] Specifically, the calculation method for the comprehensive value of drought resistance, high yield, and high efficiency of maize varieties in this invention is as follows: YWD=[(DIY / DIY)] i )+(DIWUE / DIWUE i )+(D / D i )] / 3. Based on the YWD value, the tested varieties were ranked according to drought resistance, yield, and efficiency. The larger the YWD value, the stronger the drought resistance, yield, and efficiency of the variety. The present invention further found through correlation analysis that the DI values ​​of maize dry matter at the ten-leaf stage (X1), dry matter at the silking stage (X2), dry matter at maturity (X3), SPAD value at the six-leaf stage (X4), SPAD value at the ten-leaf stage (X5), SPAD value at the silking stage (X6), SPAD value at the grain-filling stage (X7), plant height at the silking stage (X12), stem diameter at the ten-leaf stage (X13), stem diameter at the silking stage (X14), ear diameter (X16), and nitrogen accumulation at harvest (X17) were all highly significant or significantly positively correlated with the YWD value. The DI value of tip barrenness length (X15) was highly significantly negatively correlated with the YWD value, indicating that these indicators have a significant impact on the YWD value.

[0015] Preferably, the comprehensive value of drought resistance, high yield and high efficiency is calculated based on YWD=-2.878+0.120DIX1+0.096DIX2+0.278DIX3+0.897DIX4+0.713DIX6+0.570DIX7+0.127DIX14+1.196DIX16+0.141DIX18; DIX1 is the drought resistance index of dry matter at the ten-leaf stage, DIX2 is the drought resistance index of dry matter at the silking stage, DIX3 is the drought resistance index of dry matter at maturity, DIX4 is the drought resistance index of SPAD value at the six-leaf stage, DIX6 is the drought resistance index of SPAD value at the silking stage, DIX7 is the drought resistance index of SPAD value at the grain-filling stage, DIX14 is the drought resistance index of stem diameter at the silking stage, DIX16 is the drought resistance index of panicle diameter, and DIX18 is the drought resistance index of seedling emergence rate.

[0016] Specifically, this invention establishes a prediction model for the drought resistance, high yield, and high efficiency of maize varieties through stepwise regression analysis. The regression equation for the prediction model of drought resistance, high yield, and high efficiency of maize is: YWD=-2.878+0.120DIX1+0.096DIX2+0.278DIX3+0.897DIX4+0.713DIX6+0.570DIX7+0.127DIX14+1.196DIX16+0.141DIX18. The R-squared value of this regression equation is... 2The value was 0.97. According to the regression equation of the prediction model, in the identification of drought resistance, high yield and high efficiency of maize varieties, nine indicators can be selected to effectively predict and identify the drought resistance, high yield and high efficiency of maize varieties, such as dry matter at the ten-leaf stage (X1), dry matter at the silking stage (X2), dry matter at maturity (X3), SPAD value at the six-leaf stage (X4), SPAD value at the silking stage (X6), SPAD value at the grain-filling stage (X7), stem diameter at the silking stage (X14), ear diameter (X16), and emergence rate (X18), thus simplifying the screening and identification work.

[0017] On the other hand, this invention seeks protection for the application of the method for identifying drought resistance of maize varieties based on comprehensive weights in evaluating drought resistance of maize varieties.

[0018] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) This invention combines yield, water use efficiency, and multiple physiological and biochemical indicators of maize at various growth stages to comprehensively evaluate the drought resistance of maize using membership function method, principal component analysis, and comprehensive D value. The calculation method for the comprehensive value of drought resistance, high yield, and high efficiency of maize varieties is as follows: YWD=[(DIY / DIY)] i )+(DIWUE / DIWUE i )+(D / D i )] / 3. Based on the YWD value, the tested varieties were ranked according to drought resistance, yield, and efficiency. The larger the YWD value, the stronger the drought resistance, yield, and efficiency of the variety. The present invention further found through correlation analysis that the DI values ​​of maize dry matter at the ten-leaf stage (X1), dry matter at the silking stage (X2), dry matter at maturity (X3), SPAD value at the six-leaf stage (X4), SPAD value at the ten-leaf stage (X5), SPAD value at the silking stage (X6), SPAD value at the grain-filling stage (X7), plant height at the silking stage (X12), stem diameter at the ten-leaf stage (X13), stem diameter at the silking stage (X14), ear diameter (X16), and nitrogen accumulation at harvest (X17) were all highly significant or significantly positively correlated with the YWD value. The DI value of tip barrenness length (X15) was highly significantly negatively correlated with the YWD value, indicating that these indicators have a significant impact on the YWD value.

[0019] (2) This invention also establishes a drought-resistant, high-yield, and high-efficiency prediction model for varieties through stepwise regression analysis, providing a basis for large-scale variety screening in the later stage, and also providing theoretical support for improving the quality, yield, and efficiency of maize in dryland farming areas. The regression equation of the drought-resistant, high-yield, and high-efficiency prediction model for maize is: YWD=-2.878+0.120DIX1+0.096DIX2+0.278DIX3+0.897DIX4+0.713DIX6+0.570DIX7+0.127DIX14+1.196DIX16+0.141DIX18. The R-squared value of this regression equation is...2 The value of 0.97 indicates that the regression equation has a good fit and the model has a strong ability to explain the variation of the dependent variable. According to the regression equation of the prediction model, in the identification of drought resistance, high yield and high efficiency of maize varieties, nine indicators can be selected to effectively predict and identify the drought resistance, high yield and high efficiency of maize varieties, such as dry matter at the ten-leaf stage (X1), dry matter at the silking stage (X2), dry matter at maturity (X3), SPAD value at the six-leaf stage (X4), SPAD value at the silking stage (X6), SPAD value at the grain-filling stage (X7), stem diameter at the silking stage (X14), ear diameter (X16), and emergence rate (X18), thus simplifying the screening and identification work. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a statistical chart showing the rainfall and temperature in the experimental area during the maize growing season of 2023-2024.

[0022] Figure 2 The figure shows the water use efficiency of different maize varieties under mulching treatment in 2023.

[0023] Figure 3 The figure shows the water use efficiency results of different maize varieties under the unmulched treatment in 2023.

[0024] Figure 4 This figure shows the water use efficiency results of different maize varieties under mulching treatment in 2024.

[0025] Figure 5 The figure shows the water use efficiency results of different maize varieties under the unmulched treatment in 2024.

[0026] Figure 6 The graph shows the D-value results of the comprehensive evaluation of drought resistance of different maize varieties.

[0027] Figure 7 The graph shows the YWD values ​​for different varieties of corn.

[0028] Figure 8 The results of the correlation analysis between YWD values ​​and different drought resistance indicators are presented. Detailed Implementation

[0029] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials can be purchased commercially. Unless otherwise specified, the percentages in the following embodiments refer to mass percentages.

[0030] Drought Resistance Index (DI): DI = (X d / X w )×(X d / X di ).

[0031] In the formula, X d The values ​​for each indicator are the measured values ​​under uncoated conditions; X w The values ​​for each indicator are the measured values ​​under the film coating treatment; X di This represents the mean value of a certain indicator under the uncoated treatment.

[0032] Example 1 This example provides the correlation between yield and drought resistance in maize.

[0033] The experiment was conducted in Changwu, a region bordering Shaanxi and Gansu provinces in the south-central Loess Plateau, from 2023 to 2024. This area has a warm temperate semi-humid continental monsoon climate, an altitude of approximately 1200 m, an average annual temperature of 9.1℃, and significant annual rainfall variability, ranging from 300 to 700 mm. Groundwater depth is 50 to 80 m, classifying it as a typical dryland rainfed agricultural area. The soil type is black loess, characterized by its uniform and loose texture. This experimental area is also a typical representative of the plateau gully region. Before the experiment, the physicochemical properties of the 0–20 cm topsoil layer were: bulk density 1.4 g / cm³. 3 pH 7.8, organic matter 15.6 g / kg, total nitrogen 0.9 g / kg, available phosphorus 24.9 mg / kg, available potassium 117.3 mg / kg, mineral nitrogen 7.9 mg / kg.

[0034] The monthly average rainfall and average temperature during the experimental study period are as follows: Figure 1As shown, the total precipitation during the growing season was 528.2 mm in 2023 and 469.3 mm in 2024, with a 10-year average of 447.2 mm. Rainfall in 2023 and 2024 was significantly lower than the 10-year average in June and August of 2023, and May, June, and August of 2024, potentially leading to drought stress during the maize growing season. In 2024, temperatures were generally higher, especially in May (18.13℃, 2.20℃ higher than the 10-year average) and August (22.61℃, 1.26℃ higher than the 10-year average), which could exacerbate drought and negatively impact maize growth. Meteorological data from 2023 and 2024 indicate that maize may face dual stress from drought and high temperatures during its growing season, particularly in June and August.

[0035] This experiment, conducted in a field setting, screened the drought resistance of 50 maize varieties (Table 1) primarily promoted in Northwest China. The main treatments were mulching (F) and no mulching (K), with different maize varieties as subtreatments. Each plot was 25 m². 2 The planting density was 60,000 plants / ha, with equal row spacing (50 cm) and plant spacing (33.3 cm). A completely randomized block design was used, with 100 treatments, each replicated three times, for a total of 300 plots. Nitrogen fertilizer was applied at a rate of 225 kg / ha, divided into two applications: 40% before sowing and 60% at the ten-leaf stage. Phosphorus and potassium fertilizers were applied as basal fertilizers at rates of 90 kg / ha (P₂O₅) and 45 kg / ha (K₂O), respectively, before sowing.

[0036] At maturity (R6), within the designated 6 m 2 Manual harvesting was conducted within the production area. The grains were dried to constant weight, and the grain yield (t / ha) was calculated after converting the dry weight. The grain yield and drought resistance index of 50 varieties under two-year treatments with and without mulching were calculated. The drought resistance index (DI) was calculated based on the yields of the mulching and non-mulching treatments, and the varieties were ranked. The results are shown in Table 1.

[0037] Table 1. Yield and drought resistance index of different maize varieties under mulching and non-mulching treatments.

[0038] Table 1 shows that the average yield of the two-year mulching treatment was 13.88 t / ha. The top 10% yield varieties were Dongdan 1331, R1831, Lianchuang 872, Yanke 288, and Jinkeyu 3308, representing increases of 12.96%, 11.23%, 10.52%, 8.78%, and 8.29% respectively compared to the average yield. The average yield of the two-year non-mulching treatment was 12.22 t / ha, a decrease of 13.59% compared to the mulched treatment. The top 10% yield varieties were Xinghui 908, Tie 391, Yanke 288, R1831, and Jinkeyu 3308, representing increases of 17.33%, 15.47%, 13.86%, 13.68%, and 9.49% respectively compared to the average yield. The average drought resistance index of the 50 tested varieties was 0.89, fluctuating between 0.67 and 1.21. The varieties with the highest drought resistance index were Xinghui 908, Tie 391, Denghai 550, Yanke 288, and Dali 201. Among them, Xinghui 908 had the highest drought resistance index, which was 35.63% higher than the average; followed by Tie 391, which was 25.90% higher than the average. Furthermore, as shown in Figure 1, varieties with high yields do not necessarily have high drought resistance indices, indicating that using yield alone to assess the drought resistance of maize varieties is one-sided.

[0039] Example 2 This embodiment provides the correlation between water use efficiency and drought resistance in maize.

[0040] Soil samples were manually collected from 0 to 100 cm depth in each plot using a soil drill, with each 20 cm layer used to determine soil moisture content.

[0041] Soil moisture content (%) = ((wet soil + aluminum box) - (dry soil + aluminum box)) / (dry soil - aluminum box) × 100.

[0042]

[0043] In the formula, w i h represents the soil moisture content of each soil layer. i Let r be the thickness of each soil layer, and r be the unit weight of each soil layer.

[0044] ET = M1 + P + M2 In the formula, ET is the crop water consumption, M1 is the soil water storage before sowing, P is the rainfall during the growing season, and M2 is the soil water storage at harvest.

[0045] WUE=Y / ET In the formula, WUE is water use efficiency and Y is corn kernel yield.

[0046] The water use efficiency of different maize varieties was calculated using the above formula, and the results are as follows: Figures 2-5 As shown. By Figure 2 It can be seen that the average WUE of 50 maize varieties under mulching treatment in 2023 was 29.26 kg / (ha·mm). Weilong 105 had the lowest WUE at 17.25 kg / (ha·mm), while Dongdan 331 had the highest at 36.25 kg / (ha·mm). The top five varieties with the highest WUE were: Dongdan 1331, R1831, Jingke 968, Lianchuang 872, and Zhongke Yu 505. Figure 3 It can be seen that in 2023, the average WUE of 50 varieties under unfilmed treatment was 24.53 kg / (ha·mm). Weilong 105 had the lowest WUE at 17.82 kg / (ha·mm), while Xinghui 908 had the highest at 28.76 kg / (ha·mm). The top five varieties with the highest WUE were: Xinghui 908, Heheng 797, Yanke 288, R1831, and Jingke 968. Figure 4 It can be seen that the average WUE of 50 varieties under mulching treatment in 2024 was 41.26 kg / (ha·mm). Shaanxi Dan 650 had the lowest WUE at 33.09 kg / (ha·mm), while Dunyu 201 had the highest at 46.06 kg / (ha·mm). The top five varieties with the highest WUE were: Dunyu 201, Yanke 288, Jinkeyu 3308, Zengxin 817, and Dafeng 30. Figure 5 It can be seen that in 2024, the average WUE of 50 varieties under the uncoated treatment was 36.03 kg / (ha·mm). Lianchuang 808 had the lowest WUE at 24.63 kg / (ha·mm), while Xinghui 908 had the highest WUE at 43.28 kg / (ha·mm). The top 5 varieties with the highest WUE were Xinghui 908, Tie 391, Yanke 288, Jinkeyu 3308, and R1831.

[0047] Example 3 This embodiment provides the correlation between comprehensive indicators and drought resistance in maize.

[0048] 1. Analysis of drought resistance index of different corn varieties.

[0049] Two representative plant samples were randomly selected from maize at the six-leaf stage (V6), ten-leaf stage (V10), silking stage (R1), milk stage (R3), and maturity stage (R6). The aboveground parts of the collected plant samples were divided into stems, leaves, ears (husks), and kernels. After blanching at 105℃ for 30 min, the samples were dried at 70℃ to constant weight, and the dry weight was calculated. The leaf area index (LAI) of maize at the ten-leaf stage (V10), silking stage (R1), and milk stage (R3) was determined using a LAI-2200C plant canopy analyzer. Measurements were taken during times of good weather without direct sunlight. Three maize plants with uniform growth were selected from each plot. The chlorophyll content of the newly fully expanded leaves at the ten-leaf stage (V10) was measured using a portable SPAD 502. The chlorophyll content of the ear leaves at the silking stage (R1) and milk stage (R3) was measured at three locations on the leaves, and the average value was calculated. Using a steel ruler and vernier calipers, the plant height and stem diameter of maize were measured at the ten-leaf stage (V10) and the silking stage (R1). The ear diameter and tip length of harvested maize ears were measured using vernier calipers, with three ears measured per plot. The total nitrogen content of various organs of the plant at the silking stage (R1) and maturity stage (R6) was determined using the semi-micro Kjeldahl method, and the nitrogen accumulation was calculated.

[0050] Nitrogen accumulation (kg / ha) = Dry weight of each aboveground organ × Nitrogen content of each organ.

[0051] Based on the measured values ​​of indicators of 50 tested varieties at each growth stage under both mulching and non-mulching treatments, the drought resistance index (DI) of each indicator was calculated. Among them, the dry matter weight at the ten-leaf stage was X1, the dry matter weight at the silking stage was X2, the dry matter weight at maturity was X3, the SPAD value at the six-leaf stage was X4, the SPAD value at the ten-leaf stage was X5, the SPAD value at the silking stage was X6, the SPAD value at the grain-filling stage was X7, the leaf area index at the ten-leaf stage was X8, the leaf area index at the silking stage was X9, the leaf area index at the grain-filling stage was X10, the plant height at the ten-leaf stage was X11, the plant height at the silking stage was X12, the stem diameter at the ten-leaf stage was X13, the stem diameter at the silking stage was X14, the tip length was X15, the ear diameter was X16, the nitrogen accumulation at harvest was X17, and the emergence rate was X18. Analysis of the relevant parameters of the drought resistance index (DI) for each index (Table 2) revealed significant differences in DI values ​​among different varieties for the same index. The maximum drought resistance index values ​​for different varieties under indices X1 to X18 were 6.71, 3.44, 1.89, 1.22, 1.21, 1.21, 1.23, 9.40, 2.88, 5.06, 2.38, 1.46, 1.61, 1.58, 16.27, 1.27, 2.50, and 2.25 times the minimum values, respectively. This indicates that the drought resistance of different maize varieties varies considerably under the unmulched treatment. Furthermore, the coefficients of variation for each drought resistance index ranged from 0.04 to 0.38, reflecting significant differences in the sensitivity of each index to drought.

[0052] Table 2. Relevant parameters of DI for various indicators of corn.

[0053] 2. Principal component analysis of various indicators for different maize varieties Principal component analysis was used to screen out six comprehensive indicators with eigenvalues ​​greater than 1. The cumulative contribution rate of F1, F2, F3, F4, F5, and F6 was 71.09% (Table 3). Based on the absolute values ​​of the loading coefficients, it can be seen that the following parameters have higher loadings in F1: dry matter at silking stage (X2), dry matter at maturity (X3), SPAD value at six-leaf stage (X4), SPAD value at ten-leaf stage (X5), SPAD value at silking stage (X6), SPAD value at grain-filling stage (X7), plant height at silking stage (X12), tip length (X15), and ear diameter (X16); dry matter at ten-leaf stage (X1), stem diameter at ten-leaf stage (X13), nitrogen accumulation at harvest (X17), and emergence rate (X18); stem diameter at silking stage (X14) has a higher loading in F3; leaf area index at grain-filling stage (X10) has a higher loading in F4; leaf area index at silking stage (X9) and plant height at ten-leaf stage (X11) have higher loadings in F5; and leaf area index at ten-leaf stage (X8) has a higher loading in F6. Most of the information in the raw data is contained in the six comprehensive indicators, so these six comprehensive indicators can replace the 18 individual indicators for subsequent data analysis.

[0054] Table 3. Factor loading matrix and contribution rate results of principal component analysis.

[0055] 3. Comprehensive evaluation of drought resistance (D value)

[0056] In the formula, U(X) i Let ) be the membership function value of the i-th index (X1~X18), and DIX i DIX imin DIX imax represents the drought resistance index, the minimum value of the drought resistance index, and the maximum value of the drought resistance index for the i-th indicator, respectively, where n is the number of indicators.

[0057]

[0058] In the formula, W f P represents the weights of each principal component analysis factor. f Let m be the contribution rate of each principal component analysis factor, and m be the number of principal component analysis factors.

[0059]

[0060] When using the D-value calculation formula, the membership function values ​​of X1~X18 are summed and then multiplied by the weights of the principal component analysis factors of different principal components, and then summed to obtain the D-value, where n is the number of indicators.

[0061] The comprehensive drought resistance evaluation value D was calculated using the above formula, and the result is as follows: Figure 6 As shown. By Figure 6 It can be seen that the comprehensive drought resistance evaluation D value of different maize varieties ranges from 0.55 to 2.91, with an average of 1.85. Among them, Denghai 550 has the highest comprehensive drought resistance evaluation D value, followed by Xinghui 908.

[0062] 4. Comprehensive value of drought resistance, high yield and high efficiency (YWD value) YWD=[(DIY / DIY i )+(DIWUE / DIWUE i )+(D / D i )] / 3 In the formula, DIY represents the yield and drought resistance index of the tested variety. i DIWUE represents the average yield drought resistance index of all tested varieties, while DIWUE represents the water use efficiency drought resistance index of the tested varieties. i D represents the average water use efficiency drought resistance index of all tested varieties. i The average value of the drought resistance comprehensive evaluation (D value) for all tested varieties.

[0063] The drought resistance, high yield, and high efficiency comprehensive value (YWD value) of different maize varieties was calculated using the above formula, and the results are as follows: Figure 7 As shown. By Figure 7 The YWD values ​​of different maize varieties ranged from 0.62 to 1.42, with a mean of 1.00. Based on the YWD values, the tested varieties were ranked according to drought resistance, yield, and efficiency; a higher YWD value indicates stronger drought resistance, high yield, and high efficiency. Xinghui 908 had the highest YWD value.

[0064] Example 4 This embodiment provides a correlation analysis between YWD values ​​and drought resistance indices of various indicators.

[0065] The correlation analysis results between YWD value and drought resistance index of various indicators are as follows: Figure 8 As shown. By Figure 8It can be seen that the DI values ​​of dry matter at the ten-leaf stage (X1), dry matter at the silking stage (X2), dry matter at maturity (X3), SPAD value at the six-leaf stage (X4), SPAD value at the ten-leaf stage (X5), SPAD value at the silking stage (X6), SPAD value at the grain-filling stage (X7), plant height at the silking stage (X12), stem diameter at the ten-leaf stage (X13), stem diameter at the silking stage (X14), ear diameter (X16), and nitrogen accumulation at harvest (X17) are all highly significant or significantly positively correlated with the YWD value. The DI value of tip barrenness length (X15) is highly significantly negatively correlated with the YWD value, indicating that these indicators have a significant impact on the YWD value.

[0066] Because the information among the various drought resistance indices is complex and highly overlapping, a stepwise regression analysis was performed on the drought resistance indices and YWD values. Using the drought resistance indices as independent variables and YWD values ​​as the dependent variable, a stepwise regression model for predicting the drought resistance, high yield, and high efficiency of a variety was established: YWD = -2.878 + 0.120DIX1 + 0.096DIX2 + 0.278DIX3 + 0.897DIX4 + 0.713DIX6 + 0.570DIX7 + 0.127DIX14 + 1.196DIX16 + 0.141DIX18. The R-squared value of this regression equation is... 2 The value was 0.97. According to the regression equation of the prediction model, in the identification of drought resistance, high yield and high efficiency of maize varieties, nine indicators can be selected to effectively predict and identify the drought resistance, high yield and high efficiency of maize varieties, such as dry matter at the ten-leaf stage (X1), dry matter at the silking stage (X2), dry matter at maturity (X3), SPAD value at the six-leaf stage (X4), SPAD value at the silking stage (X6), SPAD value at the grain-filling stage (X7), stem diameter at the silking stage (X14), ear diameter (X16), and emergence rate (X18), thus simplifying the screening and identification work.

[0067] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A method for identifying drought resistance of maize varieties based on comprehensive weighting, characterized in that, include: Emergence rate, dry weight, SPAD value, plant height, stem diameter, and ear diameter were measured during the maize growth period. During the corn harvest period, yield, nitrogen accumulation, and tip barrenness length are measured. Soil moisture content was tested before corn planting and during corn harvest. Based on the data obtained from the test, the water use efficiency (WUE) and drought resistance comprehensive evaluation (D) value are calculated. The yield drought resistance index (DIY) and the water use efficiency drought resistance index (DIWUE) are calculated according to the drought resistance index calculation method. Then, the comprehensive value of drought resistance, high yield and high efficiency is calculated. The larger the comprehensive value of drought resistance, high yield and high efficiency, the stronger the drought resistance of the maize variety. The formula for calculating the comprehensive value of drought resistance, high yield, and high efficiency is: YWD=[(DIY / DIY)] i )+(DIWUE / DIWUE i )+(D / D i )] / 3; The DIY i The DIWUE is the average yield drought resistance index of all tested varieties. i D represents the average water use efficiency drought resistance index of all tested varieties. i The mean of the drought resistance comprehensive evaluation D values ​​for all tested varieties; The dry matter weight refers to the dry matter weight at the ten-leaf stage, the dry matter weight at the silking stage, and the dry matter weight at the maturity stage. The SPAD values ​​are the SPAD values ​​at the six-leaf stage, ten-leaf stage, silking stage, and grouting stage. The plant height mentioned is the plant height during the silking stage; The stem diameter refers to the stem diameter at the ten-leaf stage and the stem diameter at the silk-spraying stage.

2. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 1, characterized in that, The formula for calculating the comprehensive drought resistance evaluation D value is as follows: ; The U(X) i ) represents the membership function value of the i-th indicator, which consists of dry matter content, SPAD value, plant height, stem diameter, ear diameter, nitrogen accumulation, and tip barrenness length, where n is the number of indicators; The W f The weights of the principal component analysis factors.

3. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 2, characterized in that, The U(X) i The calculation method for ) is as follows: ； The DIX i Let DIX be the drought resistance index of the i-th indicator. imin The minimum value of the i-th indicator, the drought resistance index, is defined as DIX. imax Let n be the maximum value of the drought resistance index of the i-th indicator, where n is the number of indicators.

4. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 2, characterized in that, The W f The calculation method is as follows: ; The P f Let m be the contribution rate of each principal component analysis factor, and m be the number of principal component analysis factors.

5. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 1, characterized in that, The drought resistance index is calculated as follows: DI = (X d / X w )×(X d / X di ); The X d The measured value of the index is the value without coating treatment, and the X is the value of the index measured without coating treatment. w The measured value of the index under the coating treatment, namely X di The values ​​represent the average values ​​of the tested varieties without film covering.

6. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 1, characterized in that, The formula for calculating water use efficiency is: WUE = Y / ET; Y represents yield, and ET represents crop water consumption.

7. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 6, characterized in that, The formula for calculating ET is: ET = M1 + P + M2; M1 represents the soil water storage before sowing, P represents the rainfall during the growing season, and M2 represents the soil water storage at harvest.

8. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 1, characterized in that, The formula for calculating the nitrogen accumulation is: Nitrogen accumulation = Dry weight of each aboveground organ × Nitrogen content of each organ.

9. The method for identifying drought resistance of maize varieties based on comprehensive weighting according to claim 1, characterized in that, Alternatively, the comprehensive value of drought resistance, high yield, and high efficiency can be calculated based on YWD = -2.878 + 0.120DIX1 + 0.096DIX2 + 0.278DIX3 + 0.897DIX4 + 0.713DIX6 + 0.570DIX7 + 0.127DIX14 + 1.196DIX16 + 0.141DIX18. DIX1 is the drought resistance index of dry matter at the ten-leaf stage, DIX2 is the drought resistance index of dry matter at the silking stage, DIX3 is the drought resistance index of dry matter at maturity, DIX4 is the drought resistance index of SPAD value at the six-leaf stage, DIX6 is the drought resistance index of SPAD value at the silking stage, DIX7 is the drought resistance index of SPAD value at the grain-filling stage, DIX14 is the drought resistance index of stem diameter at the silking stage, DIX16 is the drought resistance index of panicle diameter, and DIX18 is the drought resistance index of seedling emergence rate.

10. The application of the method for identifying drought resistance of maize varieties based on comprehensive weighting as described in any one of claims 1 to 9 in evaluating the drought resistance of maize varieties.

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