Method for identifying and selecting drought-resistant and salt-resistant varieties of wheat in whole growth period

Abstract

The invention belongs to the technical field of agriculture, and discloses a method for identifying and selecting drought-resistant and salt-tolerant wheat varieties in a growth period, which is used for identifying and selecting the drought-resistant and salt-tolerant wheat varieties in the growth period of different wheat varieties under the stress of salt with soil salt content of 0.3% and 0.6% as a correlation analysis result of membership function values and comprehensive evaluation values of all indexes in the whole growth period of the wheat. The above-ground biomass in the heading stage and the filling stage is preliminarily determined as a key stage for evaluating the drought resistance, and can be used as an identification index for screening salt-tolerant varieties. The salt tolerance comprehensive index established through the indexes can be used for clustering test varieties, a direct and simple basis is provided for variety salt tolerance identification and grading, and the salt tolerance of wheat varieties (lines) can be well evaluated by utilizing a whole-growth-period comprehensive model.

Description

Technical Field

[0001] The present invention belongs to, but is not limited to, the field of agricultural technologies, and particularly relates to a method for screening drought-resistant and salt-tolerant wheat varieties at the germination stage and growth stage. Background Art

[0003] Problems and defects existing in the prior art are as follows:

[0004] Currently, there is no established salt-tolerance screening standard for wheat at the germination stage and growth stage. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for screening drought-resistant and salt-tolerant wheat varieties at the germination stage and growth stage.

[0006] The present invention is implemented as follows. First step: A method for screening drought-resistant and salt-tolerant wheat varieties at the germination stage and growth stage, including seed treatment, germination test, salt stress treatment, growth index measurement, data analysis, and field test.

[0007] S1: Select wheat seeds and conduct disinfection treatment.

[0008] S2: Place filter paper in a seed box, add salt stress solutions with different concentrations and water, and conduct a germination test on the seeds.

[0009] S3: Determine the appropriate concentration of NaCl for salt tolerance identification of wheat varieties at the germination stage; randomly select 4 materials from 44 wheat varieties, and treat them with solutions with mass fractions of 0 (CK), 0.8%, 1.2%, and 1.6% respectively; when the concentration of the NaCl solution is 1.2%, the germination potential and germination rate of the 4 wheat varieties show significant or extremely significant differences compared with the control, and the drought resistance and salt tolerance of each wheat material can be effectively distinguished at this NaCl solution concentration. Therefore, a NaCl solution concentration of 1.2% is determined as the appropriate concentration for wheat drought resistance and salt tolerance identification.

[0010] S4: Germinate the seeds under set temperature and light conditions at a suitable NaCl solution concentration of 1.2%, and replace the filter paper and salt stress solution every day during this period.

[0011] S5: Measure the germination rate, germination potential, root length, shoot length, fresh root weight, and fresh shoot weight of wheat seeds.

[0012] S6: Use the drought resistance index method, salt tolerance index, fuzzy membership function method, and principal component analysis method for data calculation and screening.

[0013] S7: Conduct a field test to measure the root characteristics, above-ground growth, physiological and biochemical properties, yield, and quality characteristics of wheat at different growth stages.

[0014] S8: Based on the indoor and field test data, establish the selection criteria for drought and salt tolerance during the wheat growth period.

[0015] Further, in S1, select 45 - 60 plump seeds for each material, place them in a seed box of 9×8 cm or 9×12 cm, and use 0.1% NaClO 3 solution for disinfection for 10 - 15 min, rinse with distilled water 3 times, and dry the moisture with sterile filter paper.

[0016] Further, in S2 and S3, use NaCl solution for salt stress treatment, and set the concentrations to 0%, 0.3%, 0.6%, 1.2% and 1.5%. Add them to the seed box respectively, replace the filter paper every day, and supplement the NaCl solution according to the same volume and concentration.

[0017] Further, in S4, control the day and night temperature at 25°C, the humidity at 80%, the light for 12 h, the darkness for 12 h during the germination test, and the light intensity is 400 μmol·m 2 ·s -1 .

[0018] Further, in S5, the germination standard is that the bud length is equal to half of the seed length or the root length is equal to the seed length.

[0019] Further, in S6, use Microsoft Excel 2013 for data sorting and SPSS18.0 for statistical analysis during data analysis. Calculate the drought resistance index, salt tolerance index, factor weight coefficient and salt tolerance measurement value, and conduct principal component analysis on the comprehensive indicators of each genotype.

[0020] Further, in the S7 field test, use the split - plot randomized block design, with salt treatment as the main plot and variety as the sub - plot. Set different salt treatments with soil salt contents of 0%, 0.3% and 0.6%, repeat each treatment 6 times, and use a mixture of plough layer soil, substrate and vermiculite in a ratio of 20:1 to fill a 40×25 cm flower pot to simulate the field soil environment.

[0021] Further, in S8, calculate the salt tolerance comprehensive index (CD) and salt tolerance measurement value (D) through the salt tolerance index and membership function of 18 varieties, and classify the salt tolerance of wheat varieties according to the calculation results.

[0022] Combined with the above - mentioned technical solutions and the solved technical problems, the advantages and positive effects of the technical solution to be protected by the present invention are as follows:

[0023] First, combining indoor and field experiments, under the stress of soil salt contents of 0.3% and 0.6%, 18 wheat varieties were tested for their morphological indexes during the whole growth period. According to the comprehensive drought resistance evaluation results of the tested germplasm materials, cluster analysis was carried out using the systematic clustering method. The wheat varieties with drought and salt tolerance were preliminarily determined as: Longchun 44 and Black Wheat.

[0024] The correlation analysis results of the membership function values and comprehensive evaluation values of each index during the wheat growth period under the salt stress of soil salt contents of 0.3% and 0.6% for different wheat varieties showed that the above-ground biomass at the heading stage and filling stage was preliminarily determined as the key periods for evaluating drought resistance, which could be used as the identification indexes for screening salt-tolerant varieties. The comprehensive salt tolerance index established through these indexes could cluster the tested varieties, providing a direct and simple basis for the classification of variety salt tolerance identification. The comprehensive model during the whole growth period could better evaluate the salt tolerance ability of wheat varieties (lines).

[0025] The present invention adopts the principal component analysis method to transform multiple interrelated single indexes into a small number of independent comprehensive indexes, effectively reducing the index correlation and information cross-over problems in the evaluation process. This method has been widely applied to evaluate the stress resistance potential of crops, such as maize (Deng Jie et al., 2020), soybean (Xiao Xinhui et al., 2009), nitrogen efficient utilization of wheat (Song Xiao et al., 2020), and drought resistance screening of rice germplasm resources (Pan Shiju, 2016). By calculating the principal component values, membership function values, and weight values, and normalizing the eigenvectors, the comprehensive evaluation results (D values) of wheat drought resistance were obtained. This method fully considered the mutual relationship and importance among various indexes, making the evaluation results more scientific and effective. Through the combination of multivariate statistical methods, the relative values of 11 indexes were quantified, forming a clear quantitative relationship with the drought resistance of wheat germplasm resources. The research results showed that Haiyou 3 had the strongest drought resistance among all the tested wheat germplasm resources, providing a scientific basis for the selection and improvement of wheat drought-resistant varieties. In addition, through systematic cluster analysis using D values, the wheat germplasm resources were divided into four levels: extremely strong, strong, medium, and weak, which was similar to the research results of Zhang Rui et al. (2020), providing a theoretical and practical basis for the drought resistance identification and evaluation of the wheat germplasm resources of the present invention.

[0026] (1) By comprehensively analyzing the key indicators of the entire growth period of wheat, the present invention has established an optimal regression equation model, effectively evaluating the drought resistance of wheat germplasm resources. Previous studies have mainly focused on the germination stage, seedling stage, and young spike differentiation stage of wheat, and evaluated the drought resistance of wheat by measuring indicators such as germination rate, germination index, root length, and seedling height. However, these single-index evaluation methods have limitations, while the evaluation of the entire growth period can more comprehensively reflect the drought resistance of wheat. The present invention has measured multiple indicators including 1000-grain weight, yield, SPAD value at tillering stage, tiller number, plant height at tillering stage, above-ground biomass at tillering stage, plant height at full heading stage, effective panicle number, grains per panicle, and seed setting rate, and constructed a drought resistance evaluation model through stepwise regression analysis. The predicted values of the model are consistent with the actual D-value evaluation results, indicating that the model is reliable, accurate, and efficient, and is applicable to predicting the drought resistance potential of wheat germplasm resources.

[0027] (2) The present invention uses the principal component analysis method to transform multiple interrelated single indicators into a small number of independent comprehensive indicators, effectively reducing the problems of indicator correlation and information crossover in the evaluation process. This method has been widely used in evaluating the stress resistance potential of crops, such as the nitrogen-efficient utilization of maize, soybean, and wheat, and the screening of drought resistance of rice germplasm resources. By calculating the principal component values, membership function values, and weight values, and normalizing the eigenvectors, the comprehensive evaluation result (D-value) of wheat drought resistance is obtained. This method fully considers the mutual relationship and importance among various indicators, making the evaluation result more scientific and effective. Through the combination of multivariate statistical methods, the relative values of 11 indicators are quantified, forming a clear quantitative relationship with the superiority and inferiority of the drought resistance of wheat germplasm resources. The research results show that the drought resistance of Haiyou 3 is the strongest among all the tested wheat germplasm resources, providing a scientific basis for the selection and improvement of wheat drought-resistant varieties. In addition, through systematic cluster analysis using the D-value, the wheat germplasm resources are divided into four grades: extremely strong, strong, medium, and weak, which is similar to the research results of Zhang Rui et al. (2020), providing a theoretical and practical basis for the identification and evaluation of the drought resistance of wheat germplasm resources in the present invention.

[0028] (3) The drought resistance indicators screened by the present invention not only contribute to the identification and screening of wheat germplasm resources, but also provide a scientific basis for the optimal layout of varieties. The application of these indicators can accelerate the breeding process of wheat drought-resistant varieties and improve the breeding efficiency. In addition, the methodology of the present invention also provides a reference for the stress tolerance research of other crops.

[0029] (4) Although the present invention has established a relatively accurate drought resistance evaluation model, due to the complexity of factors such as climate and soil conditions, the universality and stability of the model still need to be further verified under different environmental conditions. Future research can be carried out in a wider geographical area and different soil types to verify and optimize the model. In addition, the application of modern breeding techniques such as molecular marker-assisted selection can further improve the accuracy and efficiency of breeding drought-resistant varieties.

[0030] In summary, the present invention has successfully constructed a drought resistance evaluation model for the whole growth period of spring wheat and screened out key drought resistance indicators, providing important theoretical and practical bases for wheat drought resistance genetic improvement. Through the application of comprehensive evaluation methods, the drought resistance of wheat germplasm resources can be evaluated more comprehensively and accurately, providing scientific guidance for the breeding and utilization of wheat drought-resistant varieties. Future research should further verify and improve these methods to adapt to changing environmental conditions and breeding needs.

[0031] Second, as the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0032] 1. The expected benefits and commercial values after the transformation of the technical solution of the present invention are as follows:

[0033] (1) Improve the utilization rate of saline-alkali land and expand the cultivated land area. Salt-tolerant wheat varieties can grow normally on saline-alkali land, increasing the available cultivated land. Especially in severely saline-alkali areas, the land productivity can be improved. By planting salt-tolerant wheat crops, the originally low-yield or abandoned land can be restored to production, improving the land utilization rate.

[0034] (2) Increase crop yields and stabilize yields. Salt-tolerant varieties can still maintain relatively high yields under salt stress, reducing the yield reduction caused by salt damage and improving economic benefits. The increased yield directly brings higher economic returns, especially in saline-alkali areas.

[0035] (3) Reduce production costs and the cost of soil improvement. Salt-tolerant varieties reduce the dependence on soil improvement and reduce the input of soil improvers such as lime and gypsum.

[0036] (4) Save water resources. Salt-tolerant wheat varieties usually have a certain degree of drought resistance, reducing the irrigation demand and lowering the water resource cost.

[0037] (5) Improve the ecological environment and reduce soil degradation. Salt-tolerant wheat varieties help prevent further salinization of the soil and improve the soil structure.

[0038] (6) Enhance food security and ensure food supply. Salt-tolerant wheat varieties can stably produce in harsh environments, ensuring food supply. Especially in the context of increasing climate change, it increases the diversity of food sources and enhances the resilience of the food system.

[0039] (7) Social and economic benefits, increasing farmers' income: The high yield and low cost of salt-tolerant varieties have increased farmers' income, improved livelihoods, and promoted rural economic development.

[0040] (8) Scientific research and technological progress, promoting breeding technology progress. The cultivation of salt-tolerant wheat varieties promotes crop genetic improvement and the development of molecular breeding technology, provides valuable data for stress resistance mechanisms, and promotes agricultural scientific and technological progress.

[0041] (9) Quantitative estimation of expected benefits. The yield of salt-tolerant wheat varieties in saline-alkali land can be 20%-50% higher than that of ordinary varieties, and it also reduces soil improvement and water resource inputs, reducing production costs by 10%-30%. Considering both increased yield and cost savings, the economic benefits of salt-tolerant varieties can be increased by 30%-70%.

[0042] In summary: The expected benefits of salt-tolerant wheat varieties are significant. It can not only improve the utilization rate of saline-alkali land and crop yields, but also reduce production costs, improve the ecological environment, and bring social and economic benefits and scientific research progress. Promoting salt-tolerant varieties is of great significance for the sustainable development of agriculture and the improvement of farmers' livelihoods.

[0043] 2. The technical solution of the present invention fills the technical gaps at home and abroad in the industry:

[0044] The selection of the growth period of salt-tolerant wheat varieties is of great significance in the technical fields at home and abroad, filling a number of technical gaps, which are specifically reflected in the following aspects:

[0045] (1) Filling the gap in the combined research of salt tolerance and growth period

[0046] Limitations of traditional research: Previous studies mostly focused on single traits (such as salt tolerance or growth period), lacking systematic research on the combination of the two.

[0047] Innovative breakthrough: The selection of the growth period of salt-tolerant wheat varieties combines salt tolerance and growth period for the first time, providing new ideas for cultivating varieties adapted to different saline-alkali environments.

[0048] (2) Filling the gap in the adaptability evaluation system for salt-tolerant varieties

[0049] Comprehensive evaluation system: Traditional salt tolerance evaluations are mostly based on laboratory or short-term field trials, lacking long-term and systematic growth period adaptability evaluations. Innovative evaluation method: Through the selection of the growth period, an evaluation system for salt tolerance covering the entire growth period has been established, which can more comprehensively reflect the performance of varieties in actual production.

[0050] (3) Filling the gap in the popularization and application of salt-tolerant wheat varieties

[0051] Regional adaptability research: Through the identification and selection during the growth period, the adaptability of different salt-tolerant varieties in different saline-alkali areas was clarified, providing a scientific basis for variety promotion.

[0052] Promotion and application model: A promotion model for salt-tolerant varieties based on the identification and selection during the growth period was established, improving the accuracy and efficiency of variety promotion.

[0053] (4) Filled the gap in international salt-tolerant wheat breeding technology

[0054] International leading position: The technology of identifying and selecting the growth period of salt-tolerant wheat varieties is in the leading position internationally, providing a new method for global salt-tolerant wheat breeding and promoting the progress of global salt-tolerant wheat breeding technology.

[0055] (5) Filled the gap in the industrial development of salt-tolerant wheat varieties

[0056] Industrial development model: Through the identification and selection during the growth period, a complete chain from variety breeding to industrial development was established, promoting the industrialization of salt-tolerant wheat varieties. The industrial development of salt-tolerant wheat varieties filled the market gap and met the demand for salt-tolerant crops in saline-alkali areas.

[0057] In summary: The identification and selection of the growth period of salt-tolerant wheat varieties filled the technical gaps in the combined research of salt tolerance and growth period, adaptability evaluation system, promotion and application model, industrial development, etc. at home and abroad. The application of this technology not only promoted the progress of salt-tolerant wheat breeding technology but also provided important support for the sustainable development of agriculture.

[0058] 3. The technical solution of the present invention solves the technical problems that people have been eager to solve but have never succeeded in:

[0059] Solved the technical problem of the coordinated improvement of salt tolerance and growth period. Traditional problem: Salt tolerance and growth period are two complex traits, and it is difficult to improve them simultaneously by traditional breeding methods. Technical breakthrough: Through the technology of identifying and selecting salt tolerance during the growth period, the coordinated improvement of salt tolerance and growth period was achieved, and wheat varieties that are both salt-tolerant and adapted to different growth periods were cultivated.

[0060] 4. The technical solution of the present invention overcomes the technical prejudice:

[0061] The technical solution of the wheat growth period identification and selection overcomes the traditional technical prejudice in many aspects and promotes the progress of salt-tolerant wheat breeding. The following are the main technical prejudices overcome by this technical solution:

[0062] (1) Overcame the technical prejudice of "single trait selection"

[0063] Traditional prejudice: Traditional breeding often only focuses on a single trait (such as salt tolerance or yield) and ignores the coordinated improvement of multiple traits.

[0064] Technical breakthrough: The wheat growth stage selection technology scheme comprehensively considers multiple traits such as salt tolerance, growth stage, yield, and adaptability, realizes the coordinated selection of multiple traits, and cultivates varieties with excellent comprehensive traits.

[0065] (2) Overcame the technical bias of "disconnection between laboratory and field"

[0066] Traditional bias: Salt tolerance research mostly relies on short-term experiments under laboratory conditions, ignoring the complexity of the actual field production environment.

[0067] Technical breakthrough: This technology scheme ensures the stability and adaptability of salt-tolerant varieties in actual production through field experiments throughout the growth period, combined with laboratory data analysis.

[0068] (3) Overcame the technical bias of "no relationship between growth stage and salt tolerance"

[0069] Traditional bias: Traditional breeding believes that the growth stage and salt tolerance are independent traits, lacking in-depth research on the relationship between the two.

[0070] Technical breakthrough: This technology scheme reveals the internal relationship between the growth stage and salt tolerance, and improves the salt tolerance of varieties through growth stage regulation, filling the research gap in this field.

[0071] (4) Overcame the technical bias of "difficulty in popularizing salt-tolerant varieties"

[0072] Traditional bias: The popularization of salt-tolerant varieties lacks scientific basis and has low acceptance among farmers.

[0073] Technical breakthrough: This technology scheme, through growth stage selection, clarifies the adaptation regions and planting conditions of varieties, and significantly improves the popularization effect of salt-tolerant varieties by combining demonstration and promotion with farmer training.

[0074] (5) Overcame the technical bias of "ignoring ecological benefits in salt-tolerant breeding"

[0075] Traditional bias: Traditional salt-tolerant breeding overly pursues yield, ignoring the impact on the ecological environment.

[0076] Technical breakthrough: This technology scheme takes into account ecological benefits during the breeding process, cultivates salt-tolerant varieties that can both increase yield and improve soil structure, and promotes the sustainable development of agriculture.

[0077] In summary: The wheat growth stage selection technology scheme has successfully overcome various technical biases in traditional breeding through coordinated selection of multiple traits, combination of field and laboratory, research on the relationship between growth stage and salt tolerance, optimization of regional adaptability, improvement of breeding efficiency, scientific promotion model, and consideration of ecological benefits. This technology scheme not only promotes the progress of salt-tolerant wheat breeding but also provides strong technical support for the sustainable development of agriculture. Description of the Drawings

[0078] Figure 1 is a flowchart of the method for screening drought-resistant and salt-tolerant wheat varieties during the growth period provided by the embodiments of the present invention;

[0079] Figure 2 is a graph of the comprehensive weighted salt tolerance index and WPGMA clustering results of different wheat varieties provided by the embodiments of the present invention;

[0080] Figure 3 is a graph of the drought resistance CDC value, DC value, and D value of wheat at the germination stage provided by the embodiments of the present invention;

[0081] Figure 4 is a graph of cluster analysis and drought resistance level division provided by the embodiments of the present invention;

[0082] Figure 5 is a graph of cluster analysis of drought resistance of wheat under severe drought stress provided by the embodiments of the present invention;

[0083] Figure 6 is a graph of cluster analysis of drought resistance of wheat under moderate drought stress provided by the embodiments of the present invention;

[0084] Figure 7 is a cluster graph based on the D value provided by the embodiments of the present invention;

[0085] Figure 8 is a correlation analysis of salt tolerance coefficients at different growth stages provided by the embodiments of the present invention: pH: plant height; AFW: plant water content; ADW: aboveground dry weight; RFW: root fresh weight; RDW: root dry weight; CC: chlorophyll; LA: leaf area; the same below;

[0086] Figure 9 is a graph of the change in the comprehensive evaluation value of salt tolerance of each wheat variety at different times provided by the embodiments of the present invention;

[0087] Figure 10 is a quantitative relationship graph between the comprehensive evaluation value and the yield salt tolerance index at different growth stages provided by the embodiments of the present invention;

[0088] Figure 11 is a quantitative relationship graph between the comprehensive salt tolerance evaluation MD value and the yield drought resistance index DRI during the whole period provided by the embodiments of the present invention;

[0089] Figure 12 is a salt tolerance cluster graph based on the D value provided by the embodiments of the present invention;

[0090] Figure 13 is a correlation analysis of drought resistance coefficients at different growth stages provided by the embodiments of the present invention: V1: plant height; V2: chlorophyll; V3: leaf area; V4: aboveground fresh weight; V5: aboveground dry weight graph;

[0091] Figure 14 It is a change diagram of the comprehensive evaluation values of the drought resistance of each wheat variety at different times provided by the embodiments of the present invention;

[0092] Figure 15 It is a quantitative relationship diagram between the comprehensive evaluation values and the yield drought resistance index of each wheat variety at different growth stages in 2023 provided by the embodiments of the present invention; A: Seedling stage, B: Jointing stage, C: Heading stage, D: Filling stage;

[0093] Figure 16 It is a quantitative relationship diagram between the comprehensive evaluation values and the yield drought resistance index of each wheat variety at different growth stages in 2024 provided by the embodiments of the present invention; A: Seedling stage, B: Jointing stage, C: Heading stage, D: Filling stage;

[0094] Figure 17 It is a linear diagram of the comprehensive drought resistance evaluation value (MD) and the yield drought resistance index during the whole growth period provided by the embodiments of the present invention;

[0095] Figure 18 It is a drought resistance clustering diagram based on the D value provided by the embodiments of the present invention. Detailed implementation manners

[0096] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further describes the present invention in detail with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0097] As Figure 1 shown, the embodiments of the present invention provide a method for screening drought-resistant and salt-tolerant wheat varieties during the growth period, which is characterized in that the method includes:

[0098] S1: Select wheat seeds and perform disinfection treatment;

[0099] S2: Place filter paper in a seed box, add salt stress solutions with different concentrations and water, and conduct a germination test on the seeds;

[0100] S3: Determine the appropriate concentration of NaCl for salt tolerance identification during the germination period of wheat varieties; randomly select 4 materials from 44 wheat varieties, and treat them with solutions with mass fractions of 0 (CK), 0.8%, 1.2%, and 1.6% respectively; when the concentration of the NaCl solution is 1.2%, the germination potential and germination rate of the 4 wheat varieties all show significant or extremely significant differences compared with the control, and the drought resistance and salt tolerance of each wheat material can be effectively distinguished at this NaCl solution concentration. Therefore, it is determined that the NaCl solution concentration of 1.2% is the appropriate concentration for wheat drought resistance and salt tolerance identification;

[0101] S4: Under the suitable NaCl solution concentration of 1.2%, germinate the seeds under the set temperature and light conditions, and change the filter paper and salt stress solution every day during this period;

[0102] S5: Measure the germination rate, germination potential, root length, shoot length, fresh root weight and fresh shoot weight of wheat seeds;

[0103] S6: Use the drought resistance index method, salt tolerance index, fuzzy membership function method and principal component analysis method for data calculation and screening;

[0104] S7: Conduct a field experiment to measure the root characteristics, above-ground growth, physiological and biochemical, yield and quality characteristics of wheat at different growth stages;

[0105] S8: Based on the indoor and field experiment data, construct the selection criteria for drought and salt tolerance of wheat growth period.

[0106] The specific steps of S1 - S6 include:

[0107] Select seeds with consistent size, uniform color and plump grains, and disinfect them with 0.1% Naclo 3 solution for 10 minutes, rinse with distilled water 3 times, dry the surface moisture of the seeds with filter paper, and then place them in a seed germination box with a double-layer seed box of 9x12 cm; place 45 - 60 seeds at equal intervals in each germination box, with a day-night temperature of 25°C, a humidity of 80%, 12 hours of light, 12 hours of darkness, and a light intensity of 400 μmol·m 2 .s -1 . To determine the suitable salt concentration for screening the drought resistance of wheat varieties during the germination period, randomly select 3 materials and conduct preliminary tests with NaCl solutions at salt concentrations of 0 (CK), 0.3%, 0.6%, 1.2%, and 1.5% respectively;

[0108] Use Microsoft Excel 2013 to organize the data and SPSS18.0 for statistical analysis; take the indoor bud stage data in 2023 as the basic data, calculate the single salt and drought resistance coefficient and the comprehensive salt and drought resistance coefficient, conduct simple correlation analysis, continuous variable frequency distribution statistical analysis and principal component analysis for the DC values of each index; calculate the factor weight coefficient (ωi), the membership function value [μ(xi)] of each genotype's comprehensive index and the drought and salt tolerance measurement value respectively.

[0109] The specific steps of S7 include:

[0110] Adopt a split-plot randomized block design, with salt treatment as the main plot and variety as the sub-plot, set 3 different salt treatments of soil salt content 0% (CK), 0.3%, and 0.6% stress, and repeat each salt treatment 6 times;

[0111] Soil treatment: Dig out the 20-cm plough layer soil, mix it with substrate and vermiculite in a ratio of 20:1 to prevent soil compaction, and then evenly mix in NaCl according to soil salt contents of 0% (CK), 0.3%, and 0.6%. Fill the soil into flowerpots with dimensions of 40×25 cm, simulate the soil temperature and humidity in the field, and bury the flowerpots in the soil. Select 120 seeds of each different wheat variety, sow 25 seeds in each pot, and control the sowing depth at about 3 cm.

[0112] Calculate the salt tolerance comprehensive index (CD) and salt tolerance metric value (D) using the salt tolerance index and membership function of each index for 18 varieties, and evaluate the salt tolerance of wheat according to their magnitudes.

[0113] The cultivation and application of drought- and salt-tolerant wheat varieties are of great significance in many fields, and their related products and technologies can be widely applied in agricultural production, ecological restoration, food processing and other fields. The following are the specific application fields and related products:

[0114] 1. Agricultural production field

[0115] (1) Planting in saline-alkali land: Salt-tolerant wheat varieties can be directly planted in saline-alkali land to improve the utilization rate of saline-alkali land.

[0116] (2) Planting in arid and semi-arid regions

[0117] Salt-tolerant wheat varieties usually have a certain degree of drought resistance and are suitable for planting in arid and semi-arid regions.

[0118] (3) Development of marginal land

[0119] Utilize salt-tolerant wheat varieties to develop marginal land (such as coastal tidal flats and inland saline-alkali land).

[0120] 2. Food processing field

[0121] (1) Salt-tolerant wheat flour

[0122] The flour milled from salt-tolerant wheat can be used to make foods such as bread, noodles, and biscuits.

[0123] (2) Development of healthy foods

[0124] Salt-tolerant wheat is rich in nutrients related to stress resistance (such as antioxidants and minerals) and can be used to develop healthy foods.

[0125] 3. International cooperation and promotion field

[0126] (1) Promote salt-tolerant wheat varieties to countries and regions with severe salinization.

[0127] (2) Promote the planting technology of salt-tolerant wheat.

[0128] In summary: The application fields of salt-tolerant wheat varieties are extensive, covering multiple aspects such as agricultural production, ecological restoration, food processing, feed and animal husbandry, scientific research and breeding, and international cooperation. Related products include salt-tolerant wheat seeds, flour, feed, ecological restoration technical solutions, etc., which not only improve the utilization rate of saline-alkali land but also provide important support for ecological protection and agricultural sustainable development.

[0129] Evidence related to the technical effects obtained in the embodiments of the present invention.

[0130] 1. Indoor experiment (salt tolerance test at germination stage)

[0131] This experiment was carried out in a seed germination box in 2023. Seeds of the same size, uniform color, and plump grains were selected and disinfected with 0.1% Naclo 3 solution for 10 minutes, rinsed 3 times with distilled water, and the surface moisture of the seeds was blotted dry with filter paper and then placed in a seed germination box with a double-layer seed box of 9×12 cm. 30 seeds were placed equidistantly in each germination box, the day and night temperature was 25°C, the humidity was 80%, the light was 12 h, the darkness was 12 h, and the light intensity was 400 μmol·m -2 ·s -1 . To determine the appropriate salt concentration for screening wheat varieties at the germination stage, 3 materials were randomly selected and pre-tested with salt solutions of mass fractions of 0 (CK), 0.3%, 0.6%, 0.9%, 1.2%, and 1.5% respectively. By measuring the germination number and the growth of roots and buds, it was found that under 1.2% salt stress, the differences in various growth indicators among varieties were the most obvious, so it was selected as the standard salt concentration for identifying the salt tolerance of wheat varieties at the germination stage.

[0132] 1.1 Variety names of wheat varieties with salt tolerance in the laboratory at germination stage

[0133] In this experiment, varieties from spring wheat production areas in Gansu Province, Ningxia Hui Autonomous Region, Qinghai Province, Inner Mongolia Autonomous Region, Xinjiang Uygur Autonomous Region, etc. in China were collected, a total of 44, and the specific names and sources are shown in Table 1.

[0134] Table 1 Tested spring wheat varieties and salt tolerance D values

[0135]

[0136]

[0137] 1.2 Analysis of measured trait values of tested spring wheat varieties

[0138] Table 2 Analysis of the differences in the mean values of each measured index of the tested spring wheat varieties under salt stress and normal conditions

[0139]

[0140] Under salt stress, significant differences were observed among the seven indicators, including germination rate, root length, shoot length, fresh root weight, fresh shoot weight, dry root weight, and dry shoot weight, among different varieties (Table 2). The coefficient of variation among different varieties ranged from 32.40% to 96.63%, indicating that the 44 wheat cultivars had a rich variety and were representative, and the selected indicators were sensitive to salt stress. Under salt stress, all seven relative traits showed a significant decrease. According to the degree of decrease, the order was: shoot length (79.40%) > dry shoot weight (75.18%) > root length (72.06%) > fresh shoot weight (65.52%) > fresh root weight (60.93%) > germination rate (57.82%) > dry root weight (5.74%). This indicates that all the selected indicators were affected by salt stress during the growth and development process, and there were differences in the change ranges of different indicators, further demonstrating that it was difficult to identify the salt tolerance of the tested wheat varieties using a single indicator alone.

[0141] 1.3 Analysis of salt tolerance coefficients for each trait

[0142] Table 3 Statistical analysis of salt tolerance coefficients for each indicator of the tested spring wheat varieties

[0143]

[0144] Statistical analysis of the salt tolerance coefficients for individual traits found that, compared with the control, significant changes occurred in the trait indicators of the 44 spring wheat varieties under salt stress treatment. The coefficient of variation ranged from 35.46% to 74.40% (Table 3), indicating that the sensitivity of each indicator to salt stress was different. Under the same indicator, there were significant differences between the maximum and minimum values of the salt tolerance coefficients of different germplasms, indicating that the sensitivity of each indicator to salt stress was different.

[0145] 1.4 Principal component analysis

[0146] Table 4 Eigenvectors and contribution rates of principal components for each indicator of the tested spring wheat varieties

[0147]

[0148] As can be seen from Table 4, the contribution rates of the first 5 principal components are 27.76%, 20.84%, 15.40%, 12.14% and 9.95% respectively. These 5 principal components represent 86.09% of the information of the original 7 traits. Among them, the coefficients of the germination rate and root fresh weight in the first principal component are greater than those of other traits, indicating that the first principal component mainly reflects the information of the germination rate and root fresh weight; the coefficients of root length and shoot fresh weight in the second principal component are significantly greater than those of other traits, indicating that the second principal component mainly reflects the information of root length and shoot fresh weight; the coefficient of shoot dry weight in the third principal component is relatively large, indicating that the third principal component mainly represents the information of shoot dry weight; the coefficient of root dry weight in the fourth principal component is significantly greater than those of other traits, indicating that the fourth principal component mainly represents the information of root dry weight; the coefficient of shoot dry weight in the fifth principal component is significantly greater than those of other traits, indicating that the fifth principal component mainly represents the information of shoot dry weight.

[0149] 1.5 Comprehensive evaluation of salt tolerance of spring wheat varieties

[0150] According to the eigenvectors and membership function formulas of each single index of spring wheat varieties, calculate the membership function values and weights W of 5 comprehensive indexes j , and further calculate the comprehensive evaluation D value of the salt tolerance of spring wheat varieties and rank them. It can be seen from Table 1 that the D values of spring wheat varieties are distributed between 0.21 and 0.68. The higher the D value, the stronger the salt tolerance of the corresponding variety. Among them, the D values of Ningchun 55, Jinlang 2, Ningchun 50, Ningchun 4, and Black Wheat are relatively large, and their D values are greater than 0.6, indicating that they have strong salt tolerance; the D values of Nongmai 300, Liangchun 1354, Jiuchun 12, Ningchun 51, and Jiuchun 17 are relatively small, and their values are less than 0.2, indicating that they have weak salt tolerance.

[0151] Based on the D values of each spring wheat variety, use the group average method of Euclidean distance in DPS software to conduct cluster analysis on the salt tolerance D values ( Figure 7 ), and 44 spring wheat varieties can be divided into 5 categories. The first group (D value: 0.39 - 0.50) includes 10 spring wheat varieties, and the salt tolerance level is medium tolerance; the second group (D value: 0.21 - 0.29) includes 5 spring wheat varieties, and the salt tolerance level is highly sensitive; the third group (D value: 0.32 - 0.39) includes 4 spring wheat varieties, and the salt tolerance level is sensitive; the fourth group (D value: 0.63 - 0.68) includes 5 spring wheat varieties, and the salt tolerance level is highly tolerant; the fifth group (D value: 0.52 - 0.60) includes 20 spring wheat varieties, and the salt tolerance level is salt tolerance (Table 5).

[0152] Table 5 Screening of salt-tolerant varieties

[0153]

[0154] 2. Outdoor potted salt tolerance test

[0155] In 2023, 44 spring wheat varieties widely promoted were collected from Ningxia, Zhangye, Jiuquan, Inner Mongolia, Xinjiang and other places for NaCl solution stress tests. Eighteen spring wheat varieties with good salt tolerance at the germination stage were selected for the evaluation of salt tolerance identification indexes during the field growth period.

[0156] The experiment was set up with three treatments according to the soil salt contents of 0% (CK), 0.3% and 0.6%. First, 20 cm of plowed soil was dug in the field and vermiculite was mixed in according to the ratio of soil:vermiculite = 20:1 to prevent soil compaction. Then, NaCl was evenly mixed according to the design requirements of soil salt contents (0%, 0.3%, 0.6%), and according to the soil bulk density of 1.25 g / cm 3 It was filled into flowerpots of 40×25 cm, with 22 kg of soil in each pot. To maintain a growth environment basically similar to that in the field, the flowerpots were buried in the field soil and kept basically level with the ground. Before sowing, it was fully irrigated. When the soil reached a tillable state, sowing was carried out. 30 seeds of different wheat varieties were carefully selected and evenly sown in each pot, with a sowing depth of about 3 cm. After emergence, large and weak seedlings were pulled out, and the seedlings were thinned to 25 plants. Each treatment had 3 replicates, and 8 pots were planted in each replicate. After emergence, irrigation was carried out once every 5 days, and the total irrigation volume was 3 m 3 . The wheat varieties participating in the test are shown in Table 6.

[0157] Table 6 Test materials of different wheat varieties

[0158]

[0159] 3. Results analysis

[0160] 3.1 Effects of salt stress on the yields of different salt-tolerant wheat varieties

[0161] By analyzing the yield results (Table 7), salt stress led to a significant decrease in wheat yield; compared with the control, the average yield under 0.3% salt stress decreased by 44.26% compared with the control, and the average yield under 0.6% salt stress decreased by 52.70% compared with the control. Under normal conditions, the yields of two varieties, Jinlang 2 and Nongmai 730, were the highest. Under different salt stresses, the yield of Qingmai 7 was the highest, reaching 7367.0 kg / hm –2 and 7313.2 kg / hm –2 . Under 0.3% salt stress, the salt tolerance indexes exceeding 1.0 were Qingmai 7, Longchun 44, Qingmai 1, Nongmai 482, and Gaoyuan 437. Under 0.6% salt stress, the yield salt tolerance indexes exceeding 1.0 were Qingmai 7, Longchun 44, Gaoyuan 437, Nongmai 482, and Qingmai 1.

[0162] Table 7 Effects of salt stress on the yields of different spring wheat varieties

[0163]

[0164]

[0165] 3.2 Effects of Salt Stress on Different Traits of Spring Wheat

[0166] It can be seen from the coefficient of variation (Table 8) that, compared with the control treatment, the coefficients of variation of plant height, leaf area, and chlorophyll under salt stress at each growth stage were greater than those of the control. At the seedling stage, jointing stage, flowering stage, and filling stage of wheat under 0.3% salt content, they were 5.25% - 36.31%, 4.93% - 56.65%, 0.04% - 61.12%, and 6.85% - 29.13% respectively; at the seedling stage, jointing stage, flowering stage, and filling stage of wheat under 0.6% salt content, they were 0.12% - 71.61%, 4.09% - 73.03%, 7.28% - 68.43%, and 0.32% - 75.48% respectively. Among them, at the seedling stage and flowering stage in the early and middle growth stages under the two salt contents, the variation ranges of leaf area, above-ground dry matter, and fresh root weight were relatively large, and they were relatively sensitive to salt stress. From the average values of each index, salt stress treatment reduced plant height, leaf area, chlorophyll, plant water content, above-ground dry matter, and fresh root weight, and the leaf area decreased the most.

[0167] Table 8 Effects of Salt Stress on Different Traits of Spring Wheat

[0168]

[0169] 3.3 Correlation Analysis of Salt Tolerance Coefficients of Single Indexes at Each Growth Stage

[0170] To more accurately analyze the salt tolerance of each variety, the correlations of salt tolerance coefficients of various traits of 18 varieties under salt stress at two concentrations were analyzed ( Figure 8 ). Among the four measurement periods, there were significant correlations among the seven trait parameters. Taking the jointing stage as an example, plant height (pH) was significantly correlated with plant water content (AFW), above-ground dry weight (ADW), and leaf area (LA), and there were no significant correlations among the other traits, indicating that there was a certain degree of information overlap among the single indexes. Due to the large differences and deviations in the evaluation results of single indexes for wheat salt tolerance, it is difficult to accurately and intuitively evaluate wheat salt tolerance directly using a single index. At the same time, the roles played by each index in salt tolerance at four different growth stages were also different. To make up for the deficiencies of single-index evaluation of salt tolerance, it is necessary to further comprehensively evaluate the salt tolerance at each growth stage using principal components and membership functions.

[0171] 3.4 Principal Component Analysis of Salt Tolerance Coefficients of Single Indexes at Each Growth Stage

[0172] Principal component analysis was performed on the salt tolerance coefficients of morphological indicators at four different growth stages. At the jointing stage, booting stage, and flowering stage, 7 trait indicators were converted into 4 independent comprehensive indicators, while at the filling stage, they were converted into 3 independent comprehensive indicators. The cumulative contribution rates at the four stages reached 89.03%, 86.37%, 94.92%, and 95.23% respectively (Table 9). Generally, a cumulative contribution rate greater than 85% is considered to have strong information representativeness. These independent comprehensive indicators basically cover all the information contained in the salt tolerance-related ecological indicators at the four different stages. Therefore, these comprehensive indicators were used to comprehensively evaluate the salt tolerance of wheat varieties.

[0173] Table 9 Principal component analysis of wheat varieties at different stages

[0174]

[0175] 3.5 Comprehensive evaluation of salt tolerance at a single growth stage

[0176] The membership function was calculated for each physiological index of wheat under salt stress treatment to obtain the comprehensive evaluation SD value of salt tolerance at each stage ( Figure 9 ). At the seedling stage and filling stage, the SD value had a large range of changes, which were 0.35 - 0.68 and 0.31 - 0.62 respectively; the SD value had the smallest range of changes at the flowering stage and maturity stage. From the average SD value, the order was filling stage > seedling stage > jointing stage > flowering stage > maturity stage, indicating that the growth stage had an important impact on the comprehensive evaluation SD value. Further analysis of the quantitative relationship between the comprehensive evaluation value (SD value) of salt tolerance at each stage and the salt tolerance index of yield (DRI) ( Figure 10 ). The linear determination coefficient R2 between the SD value at the jointing stage and DRI was the highest, while that at the filling stage was the lowest, and the R2 at the seedling stage and heading stage was in the middle, which also indicated that there were certain differences in the salt tolerance of wheat at different growth stages, and the salt tolerance at different stages needed to be combined for comprehensive evaluation.

[0177] 3.6 Grey relational analysis of each morphological indicator

[0178] Grey relational analysis was performed on the salt tolerance coefficient DC of each physiological index at each stage and the comprehensive evaluation SD value (Table 10). The size of the correlation degree reflects the closeness between the DC value of the index and the comprehensive SD value. The ranking of the same morphological index at different stages differed greatly. For example, RDW ranked 4th at the seedling stage, 3rd at the jointing stage, 2nd at the flowering stage, and 6th at the filling stage.

[0179] To better utilize the contribution of individual indicators to comprehensive drought resistance, according to the ranking of grey relational degrees in each period, an equal number of morphological indicators were selected in each period successively, and principal component analysis and membership function analysis were used again to obtain the comprehensive drought resistance evaluation value (MD value) for the whole growth period. Then, a linear determination coefficient plot was made between the MD value and the yield drought resistance index ( Figure 11 ). The highest R2 between the MD value obtained by selecting the top 4 indicators with the highest grey relational degree in each period and the drought resistance index was 0.832. Selecting too few or too many indicators was not conducive to improving the determination coefficient. The top 4 indicators selected in each period were different. At the seedling stage, they were plant height, chlorophyll, leaf water content, and leaf area index; at the jointing stage, they were plant height, chlorophyll, and leaf water content; at the flowering stage, they were chlorophyll and biomass; at the filling stage, they were leaf water content and biomass. These indicators were denoted as X1 - X6 in the above order.

[0180] Table 10 Grey relational degree analysis of each physiological index

[0181]

[0182]

[0183] 3.7 Screening of salt tolerance evaluation indicators

[0184] For 18 wheat varieties, by measuring their morphological and physiological indicators at each growth stage, according to the comprehensive salt tolerance evaluation results, using the systematic clustering method ( Figure 12 ), cluster analysis was carried out on them. It was determined that the strong salt - tolerant variety with a salt tolerance index ≥ 1.3 was Qingmai 7; the relatively strong salt - tolerant varieties with a salt tolerance index of 1.3 - 1.1 were Longchun 44; the medium salt - tolerant varieties with a salt tolerance index of 1.1 - 0.8 were Nongmai 482 and Yongliang 4; the relatively weak salt - tolerant varieties with a salt tolerance index of 0.8 - 0.5 were Gaoyuan 437 and Jinlang 2; the weak salt - tolerant varieties with a salt tolerance index of 0 - 0.5 were Longchun 49, Zhangchun 27, and Black Wheat.

[0185] 4. Conclusions

[0186] Combining indoor and field experiments, under the stress of soil salt contents of 0.3% and 0.6%, for 18 wheat varieties, by measuring their morphological indicators during the whole growth period, according to the comprehensive drought resistance evaluation results of the tested germplasm materials, using the systematic clustering method, cluster analysis was carried out on them, and the drought - resistant wheat variety was preliminarily determined as: Longchun 44.

[0187] The correlation analysis results of the membership function values and comprehensive evaluation values of various indicators during the whole growth period of different wheat varieties under salt stress with soil salt contents of 0.3% and 0.6% showed that the above-ground biomass at the heading stage and filling stage was preliminarily determined as the key period for evaluating drought resistance and could be used as an identification index for screening salt-tolerant varieties. The comprehensive salt tolerance index established through these indicators can cluster the tested varieties and provide a direct and simple basis for grading the salt tolerance of varieties. The comprehensive model of the growth period can better evaluate the salt tolerance of wheat varieties (lines).

[0188] 5. Indoor experiment (drought resistance test at germination stage)

[0189] This experiment was carried out in a seed germination box in 2023. Seeds with consistent size, uniform color, and plump grains were selected and disinfected with 0.1% Naclo 3 solution for 10 min, rinsed 3 times with distilled water, and the surface moisture of the seeds was blotted dry with filter paper and then placed in a seed germination box with a double-layer seed box of 9×12 cm. 30 seeds were placed equidistantly in each germination box, with a day-night temperature of 25 °C, a humidity of 80%, a light of 12 h, darkness of 12 h, and a light intensity of 400 μmol·m -2 ·s -1 . To determine the appropriate salt concentration for screening the drought resistance of wheat varieties at the germination stage, 3 materials were randomly selected and pre-tested with PEG-6000 solutions with mass fractions of 0 (CK), 18%, 20%, and 22% respectively. By measuring the germination number and the growth of roots and buds, the differences in various growth indicators among varieties were the most obvious under 22% PEG-6000 stress, so it was selected as the standard drought concentration for identifying the drought resistance of wheat varieties at the germination stage.

[0190] 5.1 Test materials

[0191] From 2023 to 2024, 44 widely promoted wheat varieties were collected from Ningxia, Zhangye, Jiuquan, Inner Mongolia, Xinjiang and other places for PEG solution stress tests. The germination potential, germination rate, root length, root fresh weight, root dry weight, shoot length, shoot fresh weight, shoot dry weight, root number, main root length, etc. at the germination stage were measured, and 27 wheat varieties with good drought resistance at the germination stage were selected for field drought resistance identification indicators and evaluation during the whole growth period.

[0192] 5.2 Test methods

[0193] For the test materials of drought resistance in the field (Table 1), the split-plot randomized block design was adopted, with water treatment as the main plot and varieties as the sub-plot. Two irrigation amounts during the whole growth period in the field were set: 450 m 3 ·hm -2 (water-saving irrigation), 2250 m 3 ·hm -2, each treatment was repeated 3 times. The wheat varieties under test are shown in Table 1.

[0194] Table 1 Test materials of different wheat varieties

[0195]

[0196] 5.3 Project determination and methods

[0197] 5.3.1 Yield determination

[0198] At the mature stage of wheat, the number of effective panicles per unit area was investigated in each experimental plot, and each plot (with an area of 1.5 m 2 ) was threshed to measure the yield by manual harvesting. Subsequently, the samples were analyzed for seed setting in the laboratory to obtain relevant data on yield components. Finally, based on the actual harvesting data of the plot, it was converted into the yield per unit area (kg / hm 2 ).

[0199] 5.3.2 Measured indicators and methods

[0200] At the seedling stage, jointing stage, flowering stage and filling stage of wheat, plants with consistent growth vigor were selected to measure the plant height (pH). For each treatment, 15 representative plants were selected, the fresh weights of stems, leaves and spikes were weighed separately, then they were blanched in an oven at 105 °C, and then dried to a constant weight at 80 °C and the dry weights were weighed. The above-ground dry matter content, leaf water content (LWC) and plant water content (PWC) were calculated. The leaf area index (LAI) was measured by the coefficient method, and the chlorophyll content was measured with a chlorophyll meter.

[0201] 5.3.3 Data processing and analysis

[0202] Data processing refers to the method of Meng Yu. [1] Meng Yu, Tian Wenzhong, Wen Pengfei, et al. Comprehensive evaluation of drought resistance of wheat varieties based on coordination at different development stages [J]. Acta Agronomica Sinica, 2023, 49(02): 570-582.

[0203] 5.4 Data processing

[0204] Microsoft Excel 2013 was used to organize the data, and SPSS 18.0 was used for statistical analysis. Based on the indoor germination stage data in 2023, the single drought resistance coefficient (DC) and the comprehensive drought resistance coefficient (CDC) were calculated. For the DC values of each index, simple correlation analysis, continuous variable frequency distribution statistical analysis, and principal component analysis were carried out. The factor weight coefficient (ωi), the membership function value [μ(xi)] of each comprehensive index of each genotype, and the drought resistance comprehensive evaluation value (D) were calculated respectively.

[0205] 6. Results and Analysis

[0206] 6.1 Effects of Drought Stress on Yields of Wheat Varieties with Different Drought Resistances

[0207] By analyzing the two-year yield results (Table 2), drought stress led to a decrease in wheat yield, with an average yield of 4415.3 kg / hm –2 、4438.8 / hm –2 , and there were 12 with yields higher than the average. Among them, Longchun 44 had the best yield under drought stress, being 6619.5 kg / hm –2 、6643.0 kg / hm –2 , which were 68.6% and 67.2% higher than the average yield under drought stress respectively. The irrigation amount promoted the increase in wheat yield. The overall rankings of the two-year yield drought resistance indices were basically the same; for Qingchun 38 and Longchun 44, the drought resistance indices of the two-year yields both exceeded 1, being 1.03, 1.18 and 1.14, 1.34 respectively.

[0208] Table 2 Effects of Water Stress on Yields of Wheat Varieties with Different Drought Resistances

[0209]

[0210]

[0211] 6.2 Effects of Drought Stress on Main Agronomic Traits of Wheat

[0212] Based on the results of the two-year experiment (Table 3), drought stress treatment affected the agronomic traits of wheat. From the coefficient of variation, it can be seen that compared with the control treatment, the coefficient of variation of the traits under drought stress treatment in each period was larger. In 2023, the coefficients of variation of wheat at the seedling stage, jointing stage, flowering stage, and filling stage were 5.80% - 29.64%, 6.63% - 35.48%, 5.60% - 30.19%, and 5.60% - 50.26% respectively; in 2024, the coefficients of variation of wheat at the seedling stage, jointing stage, flowering stage, and filling stage were 13.14% - 29.35%, 6.26% - 22.20%, 4.56% - 28.47%, and 5.41% - 28.35% respectively. Overall, the coefficient of variation in 2023 was larger than that in 2024. The variation range of leaf area was large in all four periods, and it was relatively sensitive to drought stress. From the average values of each index, in terms of plant height, the treatments with sufficient irrigation were generally higher than those with water-saving irrigation; there was little difference in chlorophyll content between the two irrigation methods, but the chlorophyll content with sufficient irrigation was slightly higher; the leaf area, above-ground fresh weight, and dry weight were significantly higher under sufficient irrigation conditions than under water-saving irrigation conditions.

[0213] Table 3 Effects of drought stress on the main agronomic traits of wheat

[0214]

[0215] 6.3 Correlation analysis of the single-index drought resistance coefficients in each period

[0216] To more accurately analyze the drought resistance of each variety, the correlations of the drought resistance coefficients of each trait of 27 varieties under two irrigation amounts were analyzed ( Figure 13 ). Among the four measurement periods, there were significant correlations among the five trait parameters. Taking the seedling stage as an example, the leaf area (LA) was significantly correlated with plant height (pH) and chlorophyll, and the dry weight (ADW) was significantly correlated with the leaf area (LA), and there were no significant correlations among the other traits. This indicates that there is a certain degree of information overlap among the individual indicators. Due to the large differences and biases in the evaluation results of individual indicators for wheat drought resistance, it is difficult to accurately and intuitively evaluate wheat drought resistance directly using a single individual indicator. At the same time, the roles played by each indicator in the drought resistance at four different periods are also different. To make up for the deficiencies of individual indicators in evaluating drought resistance, it is necessary to further comprehensively evaluate the drought resistance in each period using principal components and membership functions.

[0217] 6.4 Principal component analysis of the single-index drought resistance coefficients under different irrigation amounts in each period

[0218] Principal component analysis was performed on the drought resistance coefficients of the morphological indicators at four different times in 2023 (Table 4). At the jointing stage and filling stage, the five indicators were converted into four independent comprehensive indicators, while at the seedling stage, they were converted into three independent comprehensive indicators. The cumulative contribution rates at the three stages reached 90.4%, 89.04%, and 85.76% in sequence, and the cumulative contribution rate at the heading stage was 93.65%. Generally, a cumulative contribution rate greater than 85% is considered to have strong information representativeness. These independent comprehensive indicators basically cover all the information contained in the ecological indicators related to drought resistance at the four different times. Therefore, these comprehensive indicators were used to comprehensively evaluate the drought and salt resistance of wheat varieties. Principal component analysis was performed on the drought resistance coefficients of the morphological indicators at four different times in 2024, which was basically similar to that in 2023.

[0219] Table 4 Principal component analysis of wheat varieties in different periods in 2023

[0220]

[0221] 6.5 Comprehensive evaluation of drought resistance at a single growth stage

[0222] From the data results of the two years, the comprehensive evaluation SD values of drought resistance at each stage were obtained by calculating the membership functions of each wheat physiological index ( Figure 14 ). At the seedling stage and filling stage, the SD value had a large range of changes, while at the jointing stage and heading stage, the SD value had the smallest range of changes. From the average SD value, the order was filling stage > seedling stage > jointing stage > heading stage, indicating that the growth stage had an important impact on the comprehensive evaluation SD value of drought resistance. Further analysis was carried out on the quantitative relationship between the comprehensive evaluation value (SD value) of drought resistance at each stage and the yield drought resistance index (DRI) ( Figure 15 ). The linear determination coefficient R2 between the SD value at the jointing stage and DRI was the highest, while that at the filling stage was the lowest. The R2 values at the seedling stage and heading stage were in the middle, which also indicated that there were certain differences in the drought resistance of wheat at different growth stages, and the drought resistance at different stages needed to be combined for comprehensive evaluation.

[0223] 6.6 Grey relational analysis of each morphological indicator

[0224] Grey relational analysis was performed on the drought resistance coefficient DC of the physiological indicators at each stage and the comprehensive evaluation SD value (Table 5). The size of the correlation degree reflected the closeness between the DC value of the indicator and the comprehensive SD value. The ranking of the same morphological indicator at different times differed greatly. For example, in 2023, chlorophyll ranked first at the seedling stage and jointing stage, second at the heading stage, and third at the filling stage; in 2024, it ranked first at the seedling stage and filling stage, third at the jointing stage, and fourth at the flowering stage.

[0225] Cluster analysis was performed on the MD value using the maximum distance method ( Figure 18) The 27 tested varieties in 2 years can be divided into 4 categories. Among them, 15 tested varieties were planted in all 3 experimental years, and their classification results were basically consistent among years. Overall, 4 varieties, Luohan 19, Luohan 22, Jinmai 47, and Liangxing 99, were classified as the first category, with the strongest drought resistance and belonging to the medium drought resistance level; 12 varieties, such as Annong 0711, Huaimai 33, and Fengdecun 21, were classified as the second category, with the second strongest drought resistance performance and belonging to the slightly weaker medium drought resistance level; 4 varieties, Zhoumai 27, Zhengmai 136, Xinmai 36, and Zhengmai 7698, were classified as the third category, with weaker drought resistance ability and belonging to the weak drought resistance level; 3 varieties, Zhongmai 895, Xinke Mai 169, and Zhoumai 98, were classified as the fourth category, with the weakest drought resistance and belonging to the extremely weak drought resistance level.

[0226] To better utilize the contribution of individual indicators to the comprehensive drought resistance, according to the ranking of the grey relational degrees in each period, an equal number of morphological indicators were selected in each period successively, and the main component analysis and membership function analysis were used again to obtain the comprehensive drought resistance evaluation value (MD value) during the whole growth period. Then, a linear determination coefficient plot was made between the MD value and the yield drought resistance index ( Figure 17 ), and a wheat whole-growth-period drought resistance screening system was constructed: DC = -0.457 + 0.75X1 + 0.89X2 (R2 = 0.9991, p < 0.001). The three selected indicators were chlorophyll at the seedling stage and plant height at the heading stage.

[0227] The highest R2 between the MD value obtained by selecting the top 4 indicators in terms of the relational degree in each period and the drought resistance index was 0.832. Selecting too few or too many indicators was not conducive to improving the determination coefficient. The top 4 indicators selected in each period were different. At the seedling stage, they were plant height, chlorophyll, leaf water content, and leaf area index; at the jointing stage, they were plant height, chlorophyll, and leaf water content; at the flowering stage, they were chlorophyll and biomass; at the filling stage, they were leaf water content and biomass. And these indicators were recorded as X1 - X6 in the above order.

[0228] Table 5 Grey relational degree analysis of each morphological indicator of each wheat variety

[0229]

[0230] 6.7 Screening of drought resistance evaluation indicators

[0231] For 27 wheat varieties, by measuring their morphological and physiological indicators during each growth period, according to the comprehensive drought resistance evaluation results, the systematic clustering method ( Figure 17 ) was used to conduct cluster analysis on them. It was determined that the strong drought resistance varieties with a drought resistance index ≥ 1 were Longchun 44 and Nongmai 4; the relatively strong drought resistance varieties with a drought resistance index of 0.8 - 1 were Jiuchun 44, Nongmai 016, 9300, Ganchun 36, Jiuchun 15, and Zhangchun 27.

[0232] 6.8 Wheat drought resistance CDC value, DC value, and D value at the germination stage based on multiple phenotypic analyses

[0233] It can be seen from Figure 15 that the CDC values and WDC values of the tested wheat varieties ranged from 0.610 - 2.256 and 0.058 - 2.519 respectively, with average values of 0.902 and 0.301 respectively, and coefficient of variation values of 0.451 and 0.495 respectively. According to the magnitudes of the CDC values and WDC values, the 44 wheat varieties were ranked for drought resistance, and the results were basically consistent.

[0234] 6.9 Cluster analysis and drought resistance level classification

[0235] It can be seen from Figure 16 that the 44 wheat varieties were divided into 4 categories at λ = 0.72. Among them, the first category was highly drought-resistant materials, with a total of 7, accounting for 15.9% of the total; the second category was moderately drought-resistant materials, with a total of 8, accounting for 18.18% of the total; the third category had 12, accounting for 36.3% of the total. In addition, according to the comprehensive drought resistance evaluation results of the tested germplasm materials, the CDC values, WDC values, and D values of these 27 tested materials were always among the top 31 in all the tested germplasm resources. A total of 27 highly drought-resistant materials, moderately drought-resistant materials, and drought-resistant materials at the germination stage were preliminarily screened for drought-resistant variety screening during the entire growth period in the field.

[0236] 7. Field drought resistance screening during the entire growth period

[0237] 7.1 Tested materials for field drought resistance (Table 6). The experiment adopted a split-plot randomized block design, with water treatment as the main plot and variety as the sub-plot. Three field irrigation amounts were set: 230 m 3 / mu (fully irrigated), 130 m 3 / mu (moderate drought stress), 30 m 3 / mu (severe drought stress), and each water treatment had 3 replicates.

[0238] Table 6 Tested materials for field drought resistance

[0239]

[0240] 7.2 Comprehensive drought resistance index and drought resistance index measurement values of each wheat variety under different water stresses

[0241] Using each morphological index of 27 wheat varieties at 5 growth stages, the comprehensive drought resistance index (CDC) and the measurement value of drought resistance index (D) were calculated, and the drought resistance of wheat was evaluated according to their magnitudes (Table 7). Under severe drought stress during the whole growth period of wheat, although there were slight differences in the ranking results of the drought resistance of 27 varieties according to the CDC value and the D value, the overall order changed little. For example, among the tested materials, the top five in terms of the CDC value were Nongmai No. 2 (30), Jiuchun No. 15 (13), Ganchun No. 36 (17), Nongmai No. 4 (26), and Jinchun No. 1 (16); when evaluated using the D value, the rankings of these 5 varieties were 1, 3, 4, 9 in sequence, indicating that the drought resistance performances of these 5 varieties were all strong under severe drought stress. There were 3 varieties with a CDC value less than 0.48 under severe drought stress, namely Ganyu No. 9 (11), Yinchun No. 10 (43), and Ningchun No. 55 (41). When evaluated using the D value under severe drought stress, their drought resistances were also weak, which indicated that both the CDC value and the D value could be used for the evaluation of wheat drought resistance under water stress and similar results could be obtained. Under moderate drought stress, the results of ranking the drought resistance of 27 wheat varieties according to these two evaluation methods of CDC and D were also similar.

[0242] Table 7 Weighted salt tolerance index and salt tolerance measurement value of each wheat variety under different salt stresses

[0243]

[0244]

[0245] 7.3 Evaluation index system for drought resistance during the whole growth period of wheat

[0246] As shown in Table 8, the correlation analysis results of the membership function values and comprehensive evaluation values of each index during the whole growth period of wheat showed that under severe drought stress, the correlation coefficients between the maturity stage and the D value were spike length, grains per spike, and grain weight, which were 0.8717, 0.8369, and 0.8018 respectively. From the perspective of the whole growth period of wheat, under moderate drought stress, the correlation coefficients between the leaf area at the seedling stage (0.6521) and the leaf area at the jointing stage (0.6956) and the D value were the largest; the correlation coefficient between the SPAD value and the D value was the largest at the heading stage (0.753), and the correlation coefficients between the fresh weight and dry weight and the D value were the largest at the heading stage (0.7186, 0.7317); under moderate water stress, similar results could also be obtained. Therefore, when screening drought-resistant varieties, spike length, grains per spike, and grain weight are important evaluation indicators, and the seedling stage, jointing stage, and heading stage are the key periods for evaluating drought resistance.

[0247] Table 8 Correlation analysis of drought resistance between the membership function values of each trait and growth stage of wheat and the D value

[0248]

[0249] 7.4 Cluster Analysis of Wheat Drought Resistance

[0250] Based on the comprehensive drought resistance evaluation results of the tested germplasm materials, cluster analysis was carried out using the systematic clustering method, and the results are as Figure 17 、 18 shown. Under severe drought stress, 27 wheat varieties can be divided into 4 categories. The first category is high drought resistance type materials with 1 variety, namely Nongmai 2; the second category is medium drought resistance type materials with 5 varieties, namely Yinchun 10, Ningchun 55, Ganyu 9, Longchun 26, Jinlang 2; the third category is medium drought resistance materials with 12 varieties. Under moderate drought stress, 27 wheat varieties can be divided into 4 categories. The first category is high drought resistance type materials with 2 varieties, namely Nongmai 2 and 9300, and the second category is medium drought resistance type materials with 7 varieties. Finally, the high drought resistance wheat variety Nongmai 2 was determined.

[0251] 8. Conclusion

[0252] Combining indoor and field experiments, under moderate and severe drought stress, 44 wheat varieties were measured for their morphological indexes during the whole growth period. Based on the comprehensive drought resistance evaluation results of the tested germplasm materials, cluster analysis was carried out using the systematic clustering method, and the drought resistance varieties of wheat were preliminarily determined as: Nongmai 2, Jiuchun 15, Ganchun 36, Nongmai 4, Jinchun 1.

[0253] The correlation analysis results of the membership function values and comprehensive evaluation values of each index of wheat during the whole growth period under severe stress, moderate drought stress and sufficient irrigation for different wheat varieties showed that the leaf area at the seedling and jointing stages, the SPAD value at the heading stage, the ear length, the number of grains per ear and the grain weight at the maturity stage were significantly correlated with the comprehensive evaluation value, indicating that the drought resistance screening system established using the leaf area at the seedling and jointing stages, the SPAD value at the heading stage, the ear length, the number of grains per ear and the grain weight at the maturity stage can evaluate the drought resistance of different wheat varieties.

[0254] Drought and salt stress severely restricts the growth and development of wheat, and the degree of influence varies in each period. In severe cases, it will lead to wheat yield reduction or even crop failure. Screening wheat drought and salt tolerance indexes and evaluating wheat drought and salt tolerance are of great importance, and then screening drought and salt tolerance wheat varieties to solve the problems of wheat yield reduction and crop failure caused by drought and salt stress in arid areas. Therefore, by identifying the drought and salt tolerance of wheat at different growth stages, it is expected to screen out effective indexes for evaluating drought and salt tolerance in each period and drought and salt tolerance lines popularized in production, providing theoretical practice and material support for the wheat drought resistance breeding process. At the same time, this has important practical significance for enriching drought and salt tolerance wheat varieties and promoting the research of wheat drought and salt tolerance.

[0255] In summary, this study successfully constructed an evaluation model for drought resistance during the entire growth period of spring wheat and screened out key drought resistance indicators, providing important theoretical and practical bases for wheat drought resistance genetic improvement. Through the application of comprehensive evaluation methods, the drought resistance of wheat germplasm resources can be evaluated more comprehensively and accurately, providing scientific guidance for the breeding and utilization of drought-resistant wheat varieties. Future research should further verify and improve these methods to adapt to changing environmental conditions and breeding requirements.

[0256] It should be noted that the embodiments of the present invention can be implemented through hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated designed hardware. Those of ordinary skill in the art can understand that the above-mentioned devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and their modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software such as firmware.

[0257] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for selecting drought-resistant and salt-tolerant wheat varieties during the growth period, comprising seed treatment, germination test, salt stress treatment, growth index determination, data analysis and field test, characterized in that: S1: Select wheat seeds and disinfect them; S2: filter paper was placed in the seed box, and salt stress solutions and clean water of different concentrations were added to conduct germination tests on the seeds; S3: Determine the appropriate concentration of NaCl for identifying salt tolerance of wheat varieties during germination; randomly select 4 materials from 44 wheat varieties, and treat them with solutions with mass fractions of 0 (CK), 0.8%, 1.2%, and 1.6%, respectively; when the concentration of NaCl solution is 1.2%, the germination potential and germination rate of the 4 wheat varieties show significant or extremely significant differences compared with the control, and the drought and salt tolerance of each wheat material can be effectively distinguished at this NaCl solution concentration, so it is determined that the NaCl solution concentration of 1.2% is the appropriate concentration for identifying drought and salt tolerance of wheat; S4: Germination was carried out at a suitable solution concentration of 1.2% NaCl under set temperature and light conditions, during which the filter paper and salt stress solution were replaced every day; S5: Determination of germination rate, germination potential, root length, sprout length, root fresh weight and sprout fresh weight of wheat seeds; S6: Data calculation and screening were performed using drought resistance index method, salt tolerance index method, fuzzy membership function method and principal component analysis method; S7: Conduct field trials to determine the root characteristics, aboveground growth, physiological and biochemical, yield and quality characteristics of wheat at different growth stages; S8: Based on indoor and field test data, construct identification criteria for drought and salt resistance during the wheat growing period.

2. The method for selecting drought-resistant and salt-tolerant wheat varieties during the growth period according to claim 1, characterized in that: In S1, 45-60 full seeds are selected from each material, placed in a 9×8 cm or 9×12 cm seed box, sterilized with 0.1% NaClO3 solution for 10-15 min, rinsed with distilled water for 3 times, and dried with sterile filter paper.

3. The method for selecting drought-resistant and salt-tolerant wheat varieties during the growth period according to claim 1, characterized in that: In S2 and S3, NaCl solution was used for salt stress treatment, and the concentrations were set to 0%, 0.3%, 0.6%, 1.2% and 1.5%, which were added to the seed boxes respectively, the filter paper was replaced every day, and NaCl solution was supplemented at the same volume and concentration.

4. The method for selecting drought-resistant and salt-tolerant wheat varieties during the growth period according to claim 1, characterized in that: In S4, the germination standard is that the sprout length is equal to half the seed length or the root length is equal to the seed length. During the germination test, the day and night temperature is controlled at 25°C, the humidity is 80%, the light is 12h, the dark is 12h, and the light intensity is 400μmol·m 2 ·s-1.

5. The method for selecting drought-resistant and salt-tolerant wheat varieties during the growth period according to claim 1, characterized in that: In S5, Microsoft Excel 2013 was used for data analysis, SPSS18.0 was used for statistical analysis, drought resistance index, salt tolerance index, factor weight coefficient and salt tolerance measurement value were calculated, and principal component analysis was performed on the comprehensive index of each genotype.

6. The method for selecting drought-resistant and salt-tolerant wheat varieties during the growth period according to claim 1, characterized in that: The S6 field trial adopted a split-plot randomized block design, with salt treatment as the main plot and variety as the sub-plot. Different salt treatments with soil salt content of 0%, 0.3% and 0.6% were set, and each treatment was repeated 6 times. A mixture of topsoil, matrix and vermiculite in a ratio of 20:1 was used to fill 40×25 cm flower pots to simulate the field soil environment.

7. The method for selecting drought-resistant and salt-tolerant wheat varieties during the growth period according to claim 1, characterized in that: The S7 calculates the salt tolerance comprehensive index (CD) and the salt tolerance measurement value (D) through the salt tolerance index and membership function of 18 varieties, and grades the salt tolerance of wheat varieties according to the calculation results.

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