A method for determining high-yielding maize varieties with high density tolerance based on competition coefficient

Abstract

This invention relates to the field of crop cultivation, and particularly to a method for determining high-yielding maize varieties with high density tolerance based on competition coefficients. The method involves setting different maize planting densities and measuring the competition coefficients at maturity under minimum and maximum density conditions. At maturity, the population yield under different density conditions is measured, and the maximum population yield of the maize variety and the optimal planting density required to achieve this maximum population yield are calculated. The coefficient of variation of ear length for different maize varieties at specific planting densities is measured, and maize varieties with low competition coefficients at maturity, low ear length coefficients of variation, and high population yields at optimal planting densities and at optimal planting densities are screened. This method comprehensively considers indicators such as competition coefficient, single ear weight, optimal planting density, and coefficient of variation. High-yielding maize varieties with high density tolerance can be screened after one season of planting, providing excellent guidance for the selection of such varieties.

Description

Technical Field

[0001] This invention relates to the field of crop cultivation, and more specifically, to a method for determining high-yielding maize varieties with high density tolerance based on a competition coefficient. Background Technology

[0002] Increasing planting density is one of the key measures to achieve high yields in maize. Different maize varieties exhibit varying degrees of tolerance to high planting density, resulting in different suitable planting densities. Selecting varieties with strong tolerance to high density is crucial for increasing yields through increased density. The tolerance of a variety to high density is an evolving concept; as maize planting density continues to increase and production levels improve, the requirements and evaluation system for the tolerance of maize varieties to high density are also constantly being adjusted.

[0003] Previous evaluation indicators and methods for maize density tolerance varied depending on the research objectives. Fan Jingsheng et al. used 47,600 plants / hm². 2 Under different planting densities, the reduction in yield per plant varied within maize populations, suggesting that yield per plant is an important indicator of density tolerance. Zhang Hongsheng et al., using a planting density of 52,500 plants / hm²... 2 and 75,000 plants / hm 2 Analysis of yield components showed that ear length, ear diameter, number of kernels per row, number of kernels per ear, and thousand-kernel weight gradually decreased with increasing density. Compared with grain yield and thousand-kernel weight, the number of kernels per ear was more significantly affected by density. Therefore, evaluating maize's tolerance to high density is complex, and it is necessary to understand the tolerance of maize varieties under high-density stress from multiple perspectives, including the plant's material productivity and yield.

[0004] Currently, the density method is commonly used to screen high-yielding, high-density-tolerant maize varieties. This method utilizes density experiments to derive a quadratic function model of yield versus density based on the relationship between population yield and density. The optimal planting density and maximum population yield for each variety are then determined using the fitted equation. While this method closely aligns with production practices, it is time-consuming and labor-intensive. It requires multi-year, multi-location trials, typically at least two years, with at least four trial sites. Furthermore, it necessitates numerous density gradient treatments, generally at least five. Additionally, this method primarily uses population yield as the measurement indicator, resulting in a simplistic approach that fails to comprehensively evaluate the characteristics of maize varieties.

[0005] Based on the above analysis, traditional methods cannot accurately screen for high-yield, high-density-tolerant maize varieties in large-scale cultivation. Therefore, it is urgent to explore a method for accurately screening high-yield, high-density-tolerant maize varieties in large-scale cultivation to improve crop material production characteristics and achieve high yields.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a method for determining high-yielding maize varieties with high density tolerance based on competition coefficients. Under different planting densities, the material accumulation and yield of each maize variety are measured. By combining three indicators—competition coefficient at maturity, population yield at maturity, and ear length variation coefficient—high-density tolerant maize varieties are screened, providing a theoretical reference for the screening and identification of high-yield and density-tolerant maize hybrids.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] A method for determining high-yielding maize varieties with high density tolerance based on competition coefficients includes the following steps:

[0010] Different maize varieties were planted at the same gradient planting density, and a control maize variety was specified among the different maize varieties.

[0011] Plant dry matter was measured at maturity under high and low competition density conditions, and the competition coefficient at maturity was calculated for each maize variety under high and low competition density conditions. The high competition density is the highest planting density in the gradient planting density, and the low competition density is the lowest planting density in the gradient planting density.

[0012] The formula for calculating the maturity competition coefficient is as follows:

[0013] ,

[0014] The dry matter content of plants at low competition density during maturity. Dry matter content of mature plants at high competition density;

[0015] Calculate the population yield of each maize variety with gradient planting density, fit the equation of gradient planting density and corresponding population yield of each maize variety, and determine the optimal planting density of each maize variety based on the equation.

[0016] The ear length of different maize varieties under the same specific gradient planting density was measured and the ear length variation coefficient was calculated, wherein the specific gradient planting density is greater than the optimal planting density;

[0017] The formula for calculating the coefficient of variation of spike length is as follows:

[0018] ;

[0019] ;

[0020] CV is the coefficient of variation for ear length, and SD is the standard deviation for ear length. This represents the average length of the spikelet;

[0021] High-yielding maize varieties with high density tolerance were selected based on their lower maturity competition coefficient, lower ear length variation coefficient, and population yield at the optimal planting density and at the optimal planting density compared to the control maize variety.

[0022] This invention provides a method for determining high-yielding, density-tolerant maize varieties based on competition coefficients. The method involves setting different maize planting densities, calculating the competition coefficient at maturity by measuring plant dry matter under minimum and maximum density conditions, and screening out maize varieties with competition coefficients lower than the control at maturity. At maturity, the method also measures population yield under different density conditions, establishes a quadratic function fitting curve of population yield versus density, calculates the maximum population yield of the maize variety and the optimal planting density required to achieve this maximum population yield, and screens out maize varieties with population yields at the optimal planting density not lower than the control, as well as varieties with optimal planting densities not lower than the control. Furthermore, the method measures ear length of different maize varieties at the same specific planting density, calculates the ear length variation coefficient, and further screens out varieties with ear length variation coefficients lower than the control. If the target maize variety meets all the above conditions, it is considered a high-yielding, density-tolerant maize variety. This method comprehensively considers indicators such as competition coefficient, single ear weight, optimal planting density, and variation coefficient, and can screen out high-yielding, density-tolerant maize varieties after one season of planting, providing excellent guidance for the selection of such varieties.

[0023] It should be noted that, in this invention, setting the same gradient planting density for different corn varieties means that different corn varieties use the same gradient planting density, and the spacing between planting rows and columns under the same gradient planting density is also the same.

[0024] In the method for determining high-yield maize varieties with high density tolerance based on competition coefficients provided by this invention, the order of steps can be adjusted according to actual needs and is not limited to the steps described above. Furthermore, to save manpower and resources, if a certain indicator of the maize variety to be determined does not meet any of the indicators mentioned above, the subsequent calculations for that maize variety can be directly abandoned; that is, the maize variety to be determined is not a high-yield maize variety with high density tolerance relative to the control maize variety.

[0025] Furthermore, if any one or more of the criteria (a)-(c) are met, the proposed corn variety should be discarded.

[0026] (a) The maturity competition coefficient of the undetermined maize variety is greater than that of the control maize variety;

[0027] (b) The yield of the undetermined maize variety was lower than that of the control maize variety at the optimal planting density;

[0028] (c) The optimal planting density of the undetermined maize variety is lower than that of the control maize variety.

[0029] Gradient planting density refers to multiple planting densities set according to a certain gradient. The planting density set in gradient planting density is generally set to 3 or more. For example, in different implementation methods, the planting density set in gradient planting density can be set to 4, 5, 6, 7, 8, etc.

[0030] Specifically, regarding the setting of gradient planting density, technicians will select a suitable planting density based on the planting density of different corn varieties, and then set 2-3 densities above and 1-2 densities below that suitable planting density. The suitable planting density can be selected based on the recommended planting density for different corn varieties or any value within a nearby range, where "nearby range" refers to no more than 2000 plants / acre above or below the recommended planting density.

[0031] Those skilled in the art will know that gradient planting density is generally set according to an arithmetic or geometric ratio, with the most common method being an arithmetic ratio. The range of arithmetic increments is 1500-3000 plants / acre, meaning the difference in density between adjacent planting areas is 1500-3000 plants / acre. In different implementations, the arithmetic increments between adjacent planting areas can be 1500 plants / acre, 1800 plants / acre, 2000 plants / acre, 2500 plants / acre, 2800 plants / acre, 3000 plants / acre, and so on.

[0032] For example, if the recommended planting density is 4500-5000 plants / mu, the suitable planting density is 4500 plants / mu, and the arithmetic progression between adjacent planting densities is 1500 plants / mu, then the gradient planting densities can be set to 3000 plants / mu, 4500 plants / mu, 6000 plants / mu, 7500 plants / mu, and 9000 plants / mu; the gradient planting densities can also be set to 3000 plants / mu, 4500 plants / mu, 6000 plants / mu, and 7500 plants / mu; the gradient planting densities can also be set to 1500 plants / mu, 3000 plants / mu, 4500 plants / mu, 6000 plants / mu, 7500 plants / mu, and 9000 plants / mu.

[0033] For example, if the recommended planting density is 4,500-5,000 plants / acre, the suitable planting density is 4,000 plants / acre, and the arithmetic progression between adjacent planting densities is 2,000 plants / acre, the gradient planting density can also be set to 2,000 plants / acre, 4,000 plants / acre, 6,000 plants / acre, 8,000 plants / acre; the gradient planting density can also be set to 2,000 plants / acre, 4,000 plants / acre, 6,000 plants / acre, 8,000 plants / acre, 10,000 plants / acre, and so on.

[0034] For example, if the recommended planting density is 4500-5000 plants / acre, the suitable planting density is 5000 plants / acre, and the arithmetic progression between adjacent planting densities is 1500 plants / acre, the gradient planting density can also be set to 3500 plants / acre, 5000 plants / acre, 6500 plants / acre, 8000 plants / acre; the gradient planting density can also be set to 3000 plants / acre, 5000 plants / acre, 7000 plants / acre, 9000 plants / acre; of course, the gradient planting density can be set even higher and / or lower, which will not be listed one by one.

[0035] For example, if the recommended planting density is 4,500-5,000 plants / acre, the appropriate planting density can be 6,000 plants / acre, the arithmetic sequence between adjacent planting densities can be 3,000 plants / acre, and the gradient planting densities can be set to 3,000 plants / acre, 6,000 plants / acre, 9,000 plants / acre, and 12,000 plants / acre.

[0036] Although corn is categorized into northern spring-sown corn, Huang-Huai Plain spring-summer corn, southern hilly corn, southwestern mountain and hilly corn, southwestern mountain and hilly corn, northwestern inland corn, and Qinghai-Tibet Plateau corn based on different planting regions and times, the planting density of these corn varieties will vary in different regions and at different planting times. When selecting gradient planting densities, one can choose the appropriate planting density based on the corresponding region and planting time, or make a rough selection. This is because the selection of an appropriate planting density serves only as a base point for setting gradient planting densities. As those skilled in the art know, gradient planting densities can have significant gradient settings; for example, the difference in the number of adjacent planting densities selected in this invention is 1500-3000 plants / acre. Therefore, whether the appropriate planting density is precisely or roughly selected will not affect the achievement of the purpose of this invention.

[0037] In this invention, when measuring the ear length of different maize varieties under the same specific gradient planting density and calculating the ear length variation coefficient, the specific gradient planting density is greater than the optimal planting density and is within the gradient planting density range one level higher than the gradient planting density closest to the optimal planting density. The following example illustrates this: If the gradient planting density is set to 3000 plants / mu, 6000 plants / mu, 9000 plants / mu, and 12000 plants / mu, and the optimal planting density for different corn varieties is 4600 plants / mu and 5400 plants / mu respectively, then both fall within the same adjacent gradient planting density range. This means the optimal planting density for different corn varieties is between 3000 plants / mu and 6000 plants / mu. Therefore, for the same specific gradient planting density, 6000 plants / mu (greater than the optimal planting density but within the closest gradient) or 9000 plants / mu (greater than the optimal planting density but one level higher) can be selected. Thus, ear length and the coefficient of variation can be calculated at either 6000 plants / mu or 9000 plants / mu. However, it should be noted that in some cases, the optimal planting density differs among different maize varieties, which may lead to different gradient planting densities used to calculate the coefficient of variation of ear length. For example, if the gradient planting density is set to 3000 plants / mu, 4500 plants / mu, 6000 plants / mu, and 7500 plants / mu, and the optimal planting density for different maize varieties is 4400 plants / mu and 4800 plants / mu respectively, then the specific gradient planting density corresponding to the maize variety with an optimal planting density of 4400 plants / mu is 4500 plants / mu or 6000 plants / mu, while the specific gradient planting density corresponding to the maize variety with an optimal planting density of 4800 plants / mu is 6000 plants / mu or 7500 plants / mu. In this invention, the specific gradient planting density used is the same for different maize varieties when calculating the coefficient of variation of ear length. Therefore, the same specific gradient planting density of 6000 plants / mu is used when calculating the coefficient of variation of ear length.

[0038] It should be noted that the gradient planting density in this invention is understood according to the context. Generally, gradient planting density refers to different planting density gradients; while a specific gradient planting density refers to a specific planting density within different planting density gradients; in expressions such as "the specific gradient planting density is greater than the optimal planting density and is within the gradient planting density range one level larger than the gradient planting density closest to the optimal planting density" and similar expressions, gradient planting density refers to a specific planting density within different planting density gradients.

[0039] Furthermore, the field area required for each planting density of each maize variety is 10-100 m². 2 .

[0040] In different embodiments, the area of ​​the field used for each planting density is 10 m². 2 12 m 2 15 m 2 18m 2 20 m 2 25m 2 30m 2 32m 2 35m 2 40m 2 50m 2 60m 2 80m 2 100m 2 And so on. Preferably, the field area required for each planting density of each maize variety is 20-30 m². 2 .

[0041] Each variety in this invention requires a small area, making it convenient for planting and testing multiple varieties.

[0042] Preferably, the number of plants used to measure the dry matter of each plant at each planting density for each corn variety is 3 or more, preferably 5-8 plants.

[0043] In different embodiments, the number of plants measured for each planting density of each maize variety can be 3, 4, 5, 6, 7, 8, 9, 10, etc. As long as it is statistically significant, it saves time and labor.

[0044] Preferably, for each planting density of each maize variety, at least 8 ears of maize are used to measure the yield and ear length of the population, and more preferably 8-15 ears.

[0045] In other words, the corn ears used to measure the yield and ear length of each corn variety at each planting density can usually be shared. Of course, they can also be shared partially or not.

[0046] In different embodiments, the number of corn ears used to measure population yield and ear length at each planting density for each corn variety can be 8, 9, 10, 11, 12, 15, etc.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] (1) This invention uses different maize varieties planted at different planting densities to determine the competition coefficient at maturity, population yield at maturity, optimal planting density and ear length variation coefficient of each maize variety, and screens out maize varieties with high density tolerance, providing a theoretical reference for the screening and identification of high-yield and density-tolerant maize hybrids.

[0049] (2) By taking into account multiple indicators, this invention can more accurately identify high-yield and dense-planting tolerant maize varieties, which not only overcomes the complexity of existing methods, but also shortens the identification cycle.

[0050] (3) This invention simplifies the complexity and uncertainty of identifying high-yield, dense-planting maize varieties, requires a small area, allows for the simultaneous testing of multiple varieties, promotes research on high-yield crop cultivation, and provides an effective means for screening high-yield, dense-planting maize varieties. Attached Figure Description

[0051] 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.

[0052] Figure 1 This is a population yield curve of different maize hybrids with different planting densities involved in Embodiment 1 of the present invention;

[0053] Figure 2 This is a population yield curve of different maize hybrids with different planting densities involved in Embodiment 2 of the present invention;

[0054] Figure 3 This is a population yield curve of different maize hybrids with different planting densities involved in Embodiment 3 of the present invention. Detailed Implementation

[0055] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0056] The following examples illustrate specific implementations.

[0057] Example 1

[0058] This invention uses collected maize hybrids and Zhengdan 958 (control variety, hereinafter referred to as CK) as test materials, and sets planting densities of 3000 plants / mu, 6000 plants / mu, 9000 plants / mu, and 12000 plants / mu, respectively. The material accumulation and yield of each maize hybrid under different densities are measured. Through three indicators, namely the competition coefficient at maturity, the coefficient of variation of ear length, the optimal planting density, and the population yield at maturity, high-yielding maize varieties with high density tolerance are gradually screened out, providing a theoretical reference for the screening and identification of high-yield and density-tolerant maize hybrids.

[0059] The experiment was conducted from 2020 to 2022 at the Anyang Experimental Station of the Cotton Research Institute, Chinese Academy of Agricultural Sciences. Field planting was carried out on alluvial soil with uniform fertility. The physicochemical properties of the 0-20 cm soil layer were as follows: available nitrogen 32.48 mg / kg, total nitrogen 0.98 g / kg, available phosphorus 10.52 mg / kg, and available potassium 138.56 mg / kg. A split-plot design with randomized block design was used. Different maize varieties were used as the main plot (the control group was Zhengdan 958, currently the most widely planted maize variety in China; the treatment groups were collected maize varieties), and different planting densities were used as subplots (planting densities of 3000 plants / mu, 6000 plants / mu, 9000 plants / mu, and 12000 plants / mu). Each treatment was planted in 4 rows, with a row length of 5 m, a row spacing of 60 cm, and a plot area of ​​12 m². 2 Sowing was carried out manually, with 3 seeds per hole. Seedlings were thinned out when the plants had 5 leaves. The middle two rows of each plot were selected to track and record the phenological changes of the plants.

[0060] 1. Measurement Items and Methods

[0061] Plant dry matter determination: At maturity, 5 representative plants were selected from each plot, placed in a drying oven at 105 ℃ for 30 min to blanch, and then dried at 80 ℃ to constant weight, and the dry weight was measured.

[0062] Yield and yield composition determination: At maturity, 10 ears were selected from each plot to measure ear length, single ear weight, and single ear grain weight. All ears in the middle two rows of the harvested plot were weighed for yield calculation. The grain moisture content was measured using PM-8188, and the yield was calculated based on a standard moisture content of 14%.

[0063] 2. Steps for screening high-yielding maize varieties with high density tolerance

[0064] Based on plant dry matter and yield data, calculate the competition coefficient at maturity (CI), the coefficient of variation of panicle length (CV), etc., using the following formulas.

[0065] ;

[0066] ;

[0067] .

[0068] The dry matter content of mature plants at low competition density (3000 plants / acre) The dry matter content of mature plants under high competition density (12,000 plants / acre); SD represents the standard deviation of ear length. This represents the average length of the spikelet;

[0069] Maize varieties that meet the following criteria are selected: competition coefficient at maturity (CI), coefficient of variation for ear length (CV), optimal planting density, and yield at maturity:

[0070] (1) CI (CK) > CI (Solicitation)

[0071] Under low competition (3000 plants / mu) and high competition (12000 plants / mu) densities, the dry matter at maturity of maize hybrids was measured, and the competition coefficient at maturity of each variety was calculated, as shown in Table 1.

[0072] Table 1 Competition coefficients at maturity of different maize varieties

[0073] variety Low-density mature dry matter (g) High-density mature dry matter (g) Competition coefficient at maturity CK 255.31 108.33 1.36 Zhongyan 698 215.91 119.5 0.81 Central Research Institute 1603 243.25 127.99 0.9

[0074] Based on the competition coefficient at maturity, maize varieties with lower coefficients than the control were screened, and two varieties were initially selected: Zhongyan 698 and Zhongyan 1603.

[0075] (2) Group output (CK) < Group output (collection)

[0076] Based on the population yield of various maize varieties under different planting densities, fitting equations for different planting densities and yields were obtained. At the highest yield, the optimal planting densities for varieties CK and Zhongyan 698 were 4712 plants / mu and 4937 plants / mu, respectively. Figure 1 As shown in the figure. Further screening revealed one variety, Zhongyan 698, which had both higher population yield and optimal planting density than the control.

[0077] (3) CV (CK) > CV (recruitment)

[0078] The ear length of each maize variety was measured at a gradient planting density greater than the optimal planting density but closest to the optimal density, i.e., 6000 plants / mu, and the ear length variation coefficient was calculated, as shown in Table 2.

[0079] Table 2. Coefficient of variation of ear length for maize varieties at a density of 6000 plants / mu

[0080] variety ear length variation coefficient CK 8.57 Zhongyan 698 6.39 Central Research Institute 1603 9.46

[0081] Finally, the variety with a lower ear length variation coefficient than the control was selected, namely Zhongyan 698.

[0082] It should be noted that if the ear length of each maize variety is selected at a density of 9,000 plants / mu and the ear length variation coefficient is calculated, the variety with the ear length variation coefficient lower than the control is Zhongyan 698, as shown in Table 3.

[0083] Table 3. Coefficient of variation of ear length for maize varieties at a density of 9000 plants / mu

[0084] variety ear length variation coefficient CK 12.93 Zhongyan 698 11.34 Central Research Institute 1603 15.63

[0085] This embodiment combines the competition coefficient at maturity, the coefficient of variation of ear length, the optimal planting density, and the population yield index at maturity to screen out the high-yield, high-density-tolerant maize variety Zhongyan 698, which is a high-yield maize variety that is both tolerant of high density and high-density-tolerant.

[0086] Statistical analysis of past data on these corn varieties reveals that Zhongyan 698 is indeed a high-yield, densely planted corn variety compared to Zhongyan 1603 and Zhengdan 958.

[0087] Example 2

[0088] The experimental protocol was the same as in Example 1, except that a different maize variety was used. The control maize variety remained Zhengdan 958 (hereinafter referred to as CK).

[0089] Under low competition (3000 plants / mu) and high competition (12000 plants / mu) conditions, the dry matter at maturity of maize hybrids was measured, and the competition coefficient at maturity of each variety was calculated, as shown in Table 4.

[0090] Table 4 Competition coefficients at maturity of different maize varieties

[0091] variety Low-density mature dry matter (g) High-density mature dry matter (g) Competition coefficient at maturity CK 255.31 108.33 1.36 MY73 212.86 132.69 0.6 Yuyu 22 181.08 85.55 1.12

[0092] Based on the competition coefficient at maturity, varieties with lower coefficients than the control were selected, and two varieties were initially selected: MY73 and Yuyu 22.

[0093] Based on the population yield of various maize varieties under different planting densities, fitting equations for different planting densities and yields were obtained. At the highest yield, the optimal planting densities for varieties CK and MY73 were 4712 plants / mu and 5075 plants / mu, respectively. Figure 2 As shown in the figure. Further screening revealed one variety, MY73, which had both higher population yield and optimal planting density than the control.

[0094] The ear length of each maize variety was measured at a gradient planting density of 6000 plants / mu (a density greater than the optimal planting density and higher than the closest to the optimal density), and the coefficient of variation of ear length was calculated, as shown in Table 5.

[0095] Table 5. Coefficient of variation of ear length for maize varieties at a density of 6000 plants / mu

[0096] variety ear length variation coefficient CK 8.57 MY73 5.21 Yuyu 22 10.45

[0097] Finally, the variety with a lower ear length variation coefficient than the control was selected, namely MY73.

[0098] It should be noted that if the ear length of each maize variety is selected at a density of 9,000 plants / acre and the ear length variation coefficient is calculated, the variety with the ear length variation coefficient lower than the control is MY73, as shown in Table 6.

[0099] Table 6. Coefficient of variation of ear length for maize varieties at a density of 9000 plants / mu

[0100] variety ear length variation coefficient CK 12.93 MY73 10.87 Yuyu 22 14.15

[0101] This embodiment combines the competition coefficient at maturity, the coefficient of variation of ear length, the optimal planting density, and the population yield index at maturity to screen out the high-yielding, high-density maize variety MY73, which is a high-yielding maize variety that is both tolerant of high density.

[0102] In addition, statistical analysis of the relationship between past planting density and yield revealed that the MY73 maize variety is indeed a high-yield maize variety that tolerates high planting density, compared to other maize varieties in this embodiment.

[0103] Example 3

[0104] The experimental scheme was the same as in Example 1, except that the density gradient and the maize varieties used were different. The density gradients were set to 1,500 plants / mu, 3,000 plants / mu, 4,500 plants / mu, 6,000 plants / mu and 7,500 plants / mu. The maize varieties to be tested were Xianyu 335 and Dika 653, and the control maize variety was still Zhengdan 958 (hereinafter referred to as CK).

[0105] Under low competition (1500 plants / mu) and high competition (7500 plants / mu) conditions, the dry matter at maturity of maize hybrids was measured, and the competition coefficient at maturity of each variety was calculated, as shown in Table 7.

[0106] Table 7 Competition coefficients at maturity of different maize varieties

[0107] variety Low-density mature dry matter (g) High-density mature dry matter (g) Competition coefficient at maturity CK 449.38 180.83 1.49 Xianyu 335 453.75 189.62 1.39 Deka 653 371.43 168.01 1.21

[0108] Based on the competition coefficient at maturity, varieties with lower coefficients than the control were selected, and two varieties were initially selected: Xianyu 335 and Dika 653.

[0109] Based on the population yield of various maize varieties under different planting densities, fitting equations for different planting densities and yields were obtained. At the highest yield, the optimal planting densities for varieties CK and Xianyu 335 were 4493 plants / mu and 4745 plants / mu, respectively. Figure 3 As shown in the figure. Further screening revealed one variety, Xianyu 335, which had both higher population yield and optimal planting density than the control.

[0110] The ear length of each maize variety was measured at a gradient planting density greater than the optimal planting density and higher than the closest to the optimal density, i.e., 6000 plants / mu, and the ear length variation coefficient was calculated, as shown in Table 8.

[0111] Table 8. Coefficient of variation of ear length for maize varieties at a density of 6000 plants / acre

[0112] variety ear length variation coefficient CK 9.86 Xianyu 335 6.74 Deka 653 14.11

[0113] Finally, the variety with a lower coefficient of variation in ear length than the control was selected, namely Xianyu 335.

[0114] This embodiment combines the competition coefficient at maturity, the coefficient of variation of ear length, the optimal planting density, and the population yield index at maturity to screen out the high-yielding, high-density maize variety Xianyu 335, which is a high-yielding maize variety that is both tolerant of high density.

[0115] In addition, statistical analysis of the relationship between past planting density and yield revealed that, compared with other corn varieties in this embodiment, the corn variety Xianyu 335 is indeed a high-yield corn variety that is tolerant of high planting density.

[0116] Although the invention has been illustrated and described with reference to specific embodiments, it should be understood that many other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications falling within the scope of the invention be included in the appended claims.

Claims

1. A method for determining high-yielding maize varieties with high density tolerance based on competition coefficients, characterized in that, Includes the following steps: Different maize varieties were planted at the same gradient planting density, and a control maize variety was specified among the different maize varieties. Plant dry matter was measured at maturity under high and low competition density conditions, and the competition coefficient at maturity was calculated for each maize variety under high and low competition density conditions. The high competition density is the highest planting density in the gradient planting density, and the low competition density is the lowest planting density in the gradient planting density. The formula for calculating the maturity competition coefficient is as follows: ， The dry matter content of plants at low competition density during maturity. Dry matter content of mature plants at high competition density; Calculate the population yield of each maize variety with gradient planting density, fit the equation of gradient planting density and corresponding population yield of each maize variety, and determine the optimal planting density of each maize variety based on the equation. The ear length of different maize varieties under the same specific gradient planting density was measured and the ear length variation coefficient was calculated, wherein the specific gradient planting density is greater than the optimal planting density and is within the gradient planting density range one level higher than the gradient planting density closest to the optimal planting density. The formula for calculating the coefficient of variation of spike length is as follows: ； ； CV is the coefficient of variation for ear length, and SD is the standard deviation for ear length. This represents the average length of the spikelet; For each maize variety and each planting density, at least 8 ears of maize were used to measure the yield and ear length of the population. High-yielding maize varieties with high density tolerance were selected based on their lower maturity competition coefficient, lower ear length variation coefficient, and population yield at the optimal planting density and at the optimal planting density compared to the control maize variety.

2. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficient according to claim 1, characterized in that, The gradient planting density is determined by selecting a suitable planting density based on the planting density of different corn varieties, and setting 2-3 densities above and 1-2 densities below the suitable planting density.

3. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficient according to claim 1, characterized in that, The gradient planting density is set in an arithmetic progression, with the arithmetic progression number set at 1500-3000 plants per acre.

4. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficient according to claim 1, characterized in that, If any one or more of the criteria (a)-(c) are met, then the pending corn variety should be discarded. (a) The maturity competition coefficient of the undetermined maize variety is greater than that of the control maize variety; (b) The yield of the undetermined maize variety was lower than that of the control maize variety at the optimal planting density; (c) The optimal planting density of the undetermined maize variety is lower than that of the control maize variety.

5. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficients according to any one of claims 1-4, characterized in that, The field area required for each planting density of each corn variety is 10-100m². 2 .

6. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficient according to claim 5, characterized in that, The field area required for each planting density of each corn variety is 20-30 m². 2 .

7. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficient according to claim 6, characterized in that, For each corn variety and each planting density, the number of plants used to measure the dry matter of the plant must be at least 3.

8. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficient according to claim 7, characterized in that, For each corn variety and each planting density, the number of plants used to measure the dry matter of the plant is 5-8.

9. The method for determining high-yielding maize varieties with high density tolerance based on competition coefficient according to claim 1, characterized in that, For each corn variety and each planting density, the measured yield and ear length were based on 8-15 ears of corn.

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