A breeding method for selecting and breeding new high-yielding and stable wheat lines

Abstract

This invention discloses a breeding method for selecting high-yielding and stable-yielding new wheat varieties, belonging to the field of crop breeding technology. The method involves crossing a high-yielding variety as the female parent and a stable-yielding and stress-resistant variety as the male parent to obtain the F1 generation; self-pollinating to obtain the F2 generation; subjecting the F2 generation to stepwise environmental stress screening under four conditions: normal water and fertilizer, drought stress, low fertility, and dense planting; alternating planting of selected individual plants in multiple environments, selecting superior lines based on a yield stability index ≥ 8.0; establishing a multi-trait weighted selection index, selecting the top 15% of lines; and finally, obtaining the target line through multi-point comparison trials. This invention achieves synergistic improvement of high and stable yields through a multi-environment synergistic screening and quantitative evaluation system, and is applicable to the breeding of new wheat varieties.

Description

Technical Field

[0001] This invention belongs to the field of crop breeding technology, and in particular relates to a method for breeding new high-yield and stable-yield wheat varieties. Background Technology

[0002] Wheat is one of the world's most important food crops, and improving its yield and stability has always been a core objective of breeding work. Traditional wheat breeding methods mainly include hybridization breeding, pedigree selection, and mixed selection. Although these methods have achieved significant results in a certain period, they generally suffer from prominent problems such as long breeding cycles, low selection efficiency, and difficulty in balancing high-yield and stable-yield traits.

[0003] In recent years, with the development of molecular biology techniques, modern breeding technologies such as molecular marker-assisted selection and genome-wide selection have been applied to wheat improvement. However, these methods often rely on specific gene loci or molecular marker information, resulting in high technical barriers, high costs, and a lack of available genotypic data for many breeding units. Furthermore, existing breeding methods often focus only on the performance of a single yield trait or under a single environmental condition in early generations, making it difficult to effectively screen for new lines that can maintain high yield levels under different environmental conditions.

[0004] While alternating selection methods across different locations, irrigated land, dry land, and plots with varying fertility have proven to be important for breeding high-yielding and stable-yielding varieties, existing methods still have significant shortcomings in terms of generational advancement efficiency, the systematic nature of selection index systems, and multi-environment synergistic screening. Therefore, developing a new wheat breeding method that does not rely on molecular markers, is easy to operate, has a short breeding cycle, and can effectively balance high-yielding and stable-yielding traits is of great practical significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for breeding high-yield and stable-yield new wheat varieties.

[0006] To achieve the above objectives, this invention provides a method for breeding high-yield and stable-yield new wheat lines, comprising the following steps: S1. Select high-yielding and high-quality wheat varieties as high-yielding parents and select stable-yielding and high-resistance wheat varieties as stable-yielding parents. Use the high-yielding parents as the female parent and the stable-yielding parents as the male parent to cross and obtain F1 generation seeds.

[0007] S2. Plant the F1 generation seeds obtained in S1 under normal cultivation conditions. After they mature, harvest all the seeds of the F1 generation plants to obtain the F2 generation seeds.

[0008] S3. Divide the F2 generation seeds obtained in S2 into four equal parts and plant them under different environmental stress conditions for screening, specifically including: F2 generation seeds were planted under normal water and fertilizer conditions as a control group; F2 generation seeds were planted under drought stress conditions, and individual plants with strong drought resistance were selected. F2 generation seeds were planted under low fertility conditions, and individual plants with high nutrient utilization efficiency were selected. F2 generation seeds were planted under dense planting conditions, and individual plants with strong population adaptability were selected.

[0009] Individual plants with excellent comprehensive traits were selected under various environmental stress conditions, and each plant was harvested to obtain F3 generation seeds for each screening direction.

[0010] Preferably, drought stress conditions are characterized by a 40%-60% reduction in total irrigation water during the entire growth period compared to normal water and fertilizer conditions; low fertility conditions are characterized by a 30%-50% reduction in the amount of basal compound fertilizer applied compared to normal water and fertilizer conditions; and dense planting conditions are characterized by a 30%-50% increase in planting density compared to normal water and fertilizer conditions.

[0011] S4. The F3 generation seeds obtained from each screening direction in S3 will be screened through alternating planting in multiple environments during the next growing season. Specifically, this includes: F3 generation seeds obtained from different screening directions were planted under normal water and fertilizer conditions, drought stress conditions, low fertility conditions and dense planting conditions according to the line, and the agronomic traits of each line under different environmental conditions were systematically identified. Based on the performance of each strain under different environmental conditions, the yield stability index of each strain was calculated. The formula for calculating the yield stability index is as follows: ; in, m This represents the average yield per plant of a certain strain under various environmental conditions. s This represents the standard deviation of the yield per plant of this strain under various environmental conditions. Based on a comprehensive selection of yield performance and yield stability index of each strain, the following strains were selected. m ≥ population mean and Is Excellent lines with a growth rate of ≥8.0 were used to obtain F4 generation seeds.

[0012] Preferably, the plants are planted in alternating environments for 2-3 generations until the traits of each strain tend to stabilize.

[0013] S5. Plant the F4 generation seeds obtained in S4 according to the line, and conduct a comprehensive multi-trait identification of each line. Measure the following trait indicators of each line: plant height, ear length, number of effective ears, number of grains per ear, thousand-grain weight, yield per plant and growth period. The weighting coefficients of each trait are determined based on their contribution to high and stable yields. The multi-trait weighted selection index for each line is then calculated. The formula for calculating the weighted selection index is as follows: ; in, W i For the first i Weighting coefficients for individual traits T i For the first i Standardized values ​​of individual traits; Based on the selection index, the superior strains ranked in the top 10%-20% were selected to obtain F5 generation seeds.

[0014] In a preferred embodiment of the present invention, the standardization treatment of the various traits adopts the range standardization formula: ; in, Let i be the measured value of the i-th trait. This represents the maximum value of this trait across all lines. This is the minimum value of this trait among all lines.

[0015] S6. Conduct comparative trials of the F5 generation seeds obtained in S5 in more than three locations with different ecological types, using the local main cultivated variety as a control. Analyze the yield data of each line in different locations, calculate the yield variation coefficient of each line, and select the line with an average yield higher than the control and a variation coefficient lower than the control to obtain the target new wheat line.

[0016] The formula for calculating the coefficient of variation of yield is: ; in, Let $\begin{pmatrix}$ be the standard deviation of the yield of a certain strain at more than three locations. The average yield of a certain strain at more than 3 locations is used; strains with an average yield increase of ≥8% compared to the control and a coefficient of variation ≤70% of the control are selected as target new wheat strains.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: (1) This invention introduces a step-by-step multi-environmental-pressure screening in the early generation (F2 generation) to simultaneously select under different adverse conditions such as drought stress, low fertility and dense planting, effectively eliminating genotypes with poor environmental adaptability, improving selection efficiency and shortening the breeding cycle.

[0018] (2) The present invention adopts a generational advancement method of alternating multiple environments, cross-planting and comprehensive evaluation of superior materials obtained from different screening directions, and combined with the quantitative evaluation of yield stability index, to achieve synergistic improvement of high yield and yield stability.

[0019] (3) This invention establishes a multi-trait weighted selection index screening system. By scientifically determining the weight coefficient of each trait, the strains are comprehensively and quantitatively evaluated. This avoids the drawbacks of relying on a single trait or subjective experience in traditional methods, and improves the accuracy and reliability of selection. 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 embodiments 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 A comparison of yields in different ecological locations. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0028] Example 1 Experimental sites: Agricultural Research and Experiment Station of Suixi County, Huaibei City, Anhui Province (Wuliying, Huaihai South Road, Suixi County) and breeding base of Anhui Yongmin Seed Industry Co., Ltd. Suixi County is located at the southern end of the Huang-Huai-Hai Plain, the site of the National Wheat Regional Experiment Station, and belongs to the southern part of the Huang-Huai winter wheat region, a typical semi-winter wheat ecological zone. The 0-20cm topsoil layer is alluvial soil, with the following basic nutrient contents: organic matter 12.5g / kg, total nitrogen 0.90g / kg, available phosphorus 17.8mg / kg, and available potassium 90mg / kg.

[0029] (1) Female parent: The wheat variety Xinong 282 (approval number: Shaanxi Approval Wheat 20220024) was selected. This variety is a semi-winter multi-spike type with a plant height of 72cm, thick and hard stems with heavy wax, and outstanding lodging resistance. In terms of yield composition, the number of spikes per mu is 418,000, the number of grains per spike is 38.5, the thousand-grain weight is 46.1g, and the average yield per mu in the two-year regional trials is 584.6kg. It has high yield potential and excellent thousand-grain weight performance.

[0030] Male parent: The wheat variety Pinyu 8155 (approval number: National Approval Wheat 20190044) was selected. This variety is a winter variety, known for its "high yield under adverse conditions, stable yield and wide adaptability". According to the identification by the Institute of Crop Science of the Chinese Academy of Agricultural Sciences, its salt tolerance is 1.34, and its salt tolerance level is Grade 1 (high tolerance). Under adverse conditions, its stress resistance mechanism responds rapidly, and the induced antioxidant enzyme activity continues to rise. It shows stable performance in different ecological zones and has strong drought and barren soil tolerance.

[0031] From April 25 to May 5, 2021 (during the heading stage of the female parent), young ears of wheat from robust plants of Xinnong 282 were selected at the breeding base in Suixi County. The upper third of the glume was cut off, and all stamens were removed with tweezers (emasculation). The ears were immediately covered with transparent sulfuric acid bags for isolation. The following day (May 6, 2021), from 8:00 to 10:00 AM, pollen from Pinyu 8155 during its pollen-shedding stage was collected. The pollen was then evenly applied to the emasculated stigma of Xinnong 282 using a cotton swab, and the ears were then covered with bags for isolation. On May 31, 2021, 25 days after the hybridization was completed, the F1 generation seeds were harvested, yielding a total of 210 plump grains.

[0032] (2) On October 10, 2021, all 210 F1 generation seeds were sown individually at the breeding base in Suixi County. The planting specifications were: row spacing 25cm, plant spacing 10cm, row length 5m, 20 seeds per row, and a total of 11 rows. Field management: 40kg / mu of compound fertilizer (N-P2O5-K2O=15-15-15) was applied as basal fertilizer; during the overwintering period (January 15, 2022), the seedlings were irrigated once with a water volume of 60m³. 3 / mu; At the jointing stage (March 20, 2022), apply 15 kg / mu of urea as a top dressing and irrigate with 60 m³ of water. 3 / mu; during the heading stage (April 25, 2022), irrigate with 50m³ of water to promote flowering. 3 / mu. After maturity (June 5, 2022), all F1 generation plants' seeds were harvested together to obtain approximately 13,500 F2 generation seeds.

[0033] (3) Stepped environmental pressure screening (F2 generation): On October 8, 2022, F2 generation seeds were divided into four equal parts by weight (approximately 3300 seeds per part, germination rate >95%), and planted at the Suixi County breeding base under the following four environmental stress conditions (each screening direction plot area was 20m²). 2 (5m long, repeated 3 times) ① Normal water and fertilizer conditions (control group).

[0034] Planting density: row spacing 25cm, plant spacing 10cm (basic seedlings approximately 160,000 per mu). Fertilization: Apply 40 kg / mu of compound fertilizer (15-15-15) as base fertilizer and 12 kg / mu of urea as top dressing during the jointing stage; Irrigation: 60m³ of water for winter (December 20th) 3 / mu, jointing water (March 25th) 60m 3 / mu, flowering water (April 28th) 50m 3 / mu, total irrigation volume for the entire growth period: 170m³ 3 / mu; Selection criteria: At maturity, 50 superior individual plants with a plant height of 70-80cm, ear length ≥9cm, and free from diseases and pests were selected as F3 generation individual plants under normal water and fertilizer conditions.

[0035] ②Drought stress conditions: Planting density: row spacing 25cm, plant spacing 10cm; Fertilization: Same as normal conditions; Irrigation: Water only for overwintering (December 20th) 50m 3 / mu and jointing water (March 25th) 40m 3 / mu, no irrigation during flowering period, total irrigation volume for the entire growth period is 90m³. 3 / mu (a decrease of about 47% compared to normal conditions); Selection criteria: Fifty individual plants with good leaf greenness retention (flag leaf senescence delayed by ≥3 days), plant height reduction of ≤15%, and yield of ≥12g per plant were selected as F3 generation individual plants under drought stress conditions.

[0036] ③ Low fertility conditions: Planting density: row spacing 25cm, plant spacing 10cm; Fertilization: Apply 20 kg / mu of compound fertilizer (15-15-15) as base fertilizer (50% less than the conventional amount), and do not apply urea as top dressing during the jointing stage; Irrigation: Same as normal conditions (total irrigation volume 170m³) 3 / mu); Selection criteria: At maturity, 50 individual plants with ≥35 grains per ear, ≥40g of 1000 grains, and ≥14g of yield per plant were selected as F3 generation individual plants under low fertility conditions.

[0037] ④ Dense planting conditions: Planting density: row spacing 15cm, plant spacing 6cm (basic seedlings approximately 280,000 per mu, an increase of about 43% compared to normal conditions); Fertilization and irrigation: as per normal conditions; Selection criteria: At maturity, 50 individual plants with robust stems (diameter of the second internode at the base ≥3.5mm), ≥6 effective panicles per plant, and lodging level ≤1 were selected as F3 generation individual plants under dense planting conditions.

[0038] Under the above environmental stress conditions, 50 plants with excellent comprehensive traits were selected at the maturity period (June 2 to June 8, 2023) (a total of 200 plants). The plants were harvested and threshed to obtain F3 generation seeds with 4 screening directions.

[0039] (4) Multi-environmental alternation selection and yield stability index screening: On October 5, 2023, a total of 200 F3 generation lines obtained from the above four screening directions were planted in the breeding base of Suixi County under normal water and fertilizer, drought stress, low fertility and dense planting conditions for multi-environmental identification.

[0040] The environmental conditions are the same as in (3).

[0041] Planting method: Each line was planted in 2 rows (row length 2m, row spacing 25cm, plant spacing 10cm), with 20 plants per row, with 3 replicates and a completely randomized block design. Each line was planted in the field according to its source, labeled as normal water and fertilizer source, drought stress source, low fertility source, and dense planting source.

[0042] Yield measurements were conducted on all lines during the maturity period (June 5 to June 10, 2024) under various environmental conditions. The yield stability index Is for each line was calculated using the following formula: ; in, m This represents the average yield per plant of a certain strain under four environmental conditions. s This represents the standard deviation of the yield per plant of this strain under four environmental conditions.

[0043] Select those that simultaneously satisfy m ≥18.0g / plant (population average) and Is Lines with a value ≥8.0 were selected as superior lines. In this example, a total of 58 lines were selected, numbered from L-001 to L-058 (Is measured range 8.2-16.5).

[0044] (5) Screening by weighted selection index of multiple traits: On October 8, 2024, the 58 selected F4 generation lines were planted under normal cultivation conditions at the breeding base in Suixi County (same as 3). Each line was planted in 6 rows (row length 5m, row spacing 25cm, plant spacing 10cm), with 3 replicates.

[0045] During the growing season, field management is the same as under (3) normal conditions. Field signs record the origin and number of the strain.

[0046] From May 25 to June 5, 2025 (late grain filling to maturity), 20 consecutive plants from the middle row of each line were randomly selected for indoor seed testing, and the following 7 trait indicators were measured: plant height (cm), panicle length (cm), number of effective panicles (panicle / plant), number of grains per panicle (grains), thousand-grain weight (g), yield per plant (g), and growth period (d).

[0047] After each trait was measured, the range was standardized using the following formula: ; in, Let i be the measured value of the i-th trait. This represents the maximum value of this trait across all lines. This is the minimum value of this trait among all lines.

[0048] The analytic hierarchy process (AHP) was used to construct pairwise judgment matrices. After consistency test (CR=0.023<0.1), the weight coefficients Wi of each trait were determined as follows: yield per plant 0.30, number of grains per ear 0.18, thousand-grain weight 0.15, number of effective ears 0.14, plant height 0.10, ear length 0.08, and growth period 0.05.

[0049] Calculate the overall selection index: ; in, W i For the first i Weighting coefficients for individual traits T i For the first i Standardized values ​​of individual traits.

[0050] Based on the SI values, the top 15% of strains were selected (58 × 15% ≈ 9 strains). Within each selected strain, the best-performing individual plant was chosen and numbered using the format "F5-(F4 serial number)-serial number". The final 9 strains are: F5-023-1, F5-041-1, F5-017-1, F5-015-2, F5-038-3, F5-056-1, F5-029-1, F5-047-2, and F5-052-1.

[0051] (6) In October 2025, the nine selected F5 generation strains will be tested in three different ecological locations.

[0052] Location A (Suixi County, Huaibei Plain Irrigation Area): Suixi Breeding Base of Anhui Yongmin Seed Industry Co., Ltd., with an average annual rainfall of 580 mm, soil in the 0-20 cm depth being alluvial soil, organic matter of 12.5 g / kg, and fertility of medium to high, belonging to the typical ecological type of irrigation area in the Huanghuai Plain; Location B (Taihe County, Huaibei dryland): The average annual rainfall is 530 mm. The soil is sandy black soil with moderate water and fertilizer retention capacity. It belongs to the Huaibei dryland ecological type. Location C (Woyang County, Huaibei Hilly Area): Average annual rainfall of 500 mm, soil is brown soil with medium to low fertility, belonging to the Huaibei hilly area ecological type.

[0053] Each location was replicated three times, using a randomized block design with a cell size of 15m². 2 (Row length 6m, width 2.5m, 10 rows). Jimai 22 was used as the control variety (CK). Jimai 22 is a commonly used control variety in regional trials of semi-winter wheat varieties in Anhui Province, and it has wide adaptability and representativeness in the southern part of the Huang-Huai winter wheat region. Field management was carried out according to the conventional production management methods of each location.

[0054] A unified harvest and yield measurement will be conducted in June 2026, and the coefficient of variation will be used as the stability evaluation index for the yield data of each strain. ; in, Let $\begin{pmatrix}$ be the standard deviation of the yield of a certain strain at more than three locations. This represents the average yield of a certain strain at more than three locations.

[0055] The average yield was ≥8% higher than that of the control variety Jimai 22, and the coefficient of variation was ≤70% of that of the control. In this embodiment, the strain number F5-023-1 was finally selected as the target new wheat strain. Its average yield at three locations was 598.6 kg / mu, which was 11.0% higher than that of the control variety Jimai 22 (average yield 539.2 kg / mu), and the coefficient of variation was only 1.42%.

[0056] Table 1 shows the main traits and rankings of the F5 generation lines selected in the F4 generation multi-trait index screening.

[0057] Table 1. Comparison of yield performance and stability of strains obtained by different breeding methods

[0058] Table 1 shows that the comprehensive quantitative evaluation using the multi-trait weighted selection index (SI) enables the scientific ranking of superior lines. Lines with high selection index rankings exhibit excellent performance in key traits such as yield per plant, number of grains per ear, and thousand-grain weight, with good coordination among the traits. This method effectively avoids the limitations of traditional selection methods that rely solely on a single trait.

[0059] Example 2 The target line F5-023-1, bred using the methods described in the above embodiments, and the control line bred using conventional pedigree methods (the same hybrid combination Xinong 282 / Pinyu 8155, but with continuous single-plant selection only up to the F5 generation under high fertilizer conditions) were compared in yield at three ecological locations. The results are shown in Table 2. Yield comparisons at different ecological locations are as follows: Figure 1 As shown.

[0060] Table 2 Comparison of yield performance and stability of strains obtained by different breeding methods

[0061] As shown in Table 2, the average yield of the nine strains bred by the method of this invention was 589.0 kg / mu, which was 9.5% higher than the conventional pedigree method control (537.8 kg) and 8.1% higher than the mixed selection control (544.9 kg). The mean coefficient of variation of each strain was 1.49%, which was much lower than the 6.28% and 5.02% of the control, indicating that the strains bred by the method of this invention showed excellent high and stable yield characteristics under different ecological conditions.

[0062] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for breeding high-yield and stable-yield new wheat lines, characterized in that, Includes the following steps: S1. Select a high-yielding wheat variety as the female parent and a stable-yielding and stress-resistant wheat variety as the male parent for hybridization to obtain F1 generation seeds; S2. Plant the F1 generation seeds obtained in S1. After they mature, harvest all the seeds from the F1 generation plants to obtain F2 generation seeds. S3. Divide the F2 generation seeds obtained in S2 into four equal parts and plant them under normal water and fertilizer conditions, drought stress conditions, low fertility conditions and dense planting conditions respectively to carry out stepwise environmental pressure screening. Select individual plants with excellent comprehensive traits under each environmental condition, harvest individual plants, and obtain F3 generation seeds for each screening direction. S4: The F3 generation seeds obtained from each screening direction in S3 were planted under normal water and fertilizer conditions, drought stress conditions, low fertility conditions, and dense planting conditions for alternating multi-environment planting. The yield of each line under different environmental conditions was measured, and the yield stability index Is of each line was calculated. ； in, μ This represents the average yield per plant of a certain strain under various environmental conditions. σ This represents the standard deviation of the yield per plant of this strain under various environmental conditions. F4 generation seeds were obtained by selecting lines with μ ≥ population mean and Is ≥ 8.0; S5. Plant the F4 generation seeds obtained in S4 according to the plant lines, and conduct multi-trait comprehensive identification on each line. Measure the plant height, ear length, number of effective ears, number of grains per ear, thousand-grain weight, yield per plant, and growth period of each line. Standardize the measured values ​​of each trait, and calculate the multi-trait weighted selection index of each line based on the weight coefficients of each trait. SI : ； in, W i For the first i Weighting coefficients for individual traits T i For the first i Standardized values ​​of individual traits; Select the top 10%-20% of superior strains based on the selection index to obtain F5 generation seeds; S6. Conduct multi-point comparison trials of the F5 generation seeds obtained in S5 at more than 3 locations with different ecological types. Using the local main cultivated variety as a control, analyze the yield data of each line at different locations, calculate the yield variation coefficient of each line, and select the line with an average yield higher than the control and a variation coefficient lower than the control to obtain the target new wheat line.

2. The method according to claim 1, characterized in that: In S3, drought stress conditions are defined as a 40%-60% reduction in total irrigation water during the entire growth period compared to normal water and fertilizer conditions; low fertility conditions are defined as a 30%-50% reduction in the amount of basal compound fertilizer applied compared to normal water and fertilizer conditions; and dense planting conditions are defined as a 30%-50% increase in planting density compared to normal water and fertilizer conditions.

3. The method according to claim 1, characterized in that: In S3, the number of superior F2 generation plants selected under various environmental stress conditions was 40-60.

4. The method according to claim 1, characterized in that: In S4, multiple environments are alternately planted for 2-3 generations until the phenotypic expression of each strain tends to be stable.

5. The method according to claim 1, characterized in that, In S5, the standardization of each trait is performed using the range standardization formula: ； in, Let i be the measured value of the i-th trait. This represents the maximum value of this trait across all lines. This is the minimum value of this trait among all lines.

6. The method according to claim 1, characterized in that: Strains ranked in the top 15% by index were selected in S5.

7. The method according to claim 1, characterized in that, The formula for calculating the coefficient of variation of output in S6 is: ； in, Let $\begin{pmatrix}$ be the standard deviation of the yield of a certain strain at more than three locations. The average yield of a certain strain at more than 3 locations is used; strains with an average yield increase of ≥8% compared to the control and a coefficient of variation ≤70% of the control are selected as target new wheat strains.

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