Identification method and application of millet high-temperature-resistant germplasm

Abstract

The invention relates to an identification method and application of millet high-temperature-resistant germplasm, and belongs to the technical field of millet stress resistance identification. The identification method comprises the following steps: carrying out high temperature stress in a growth period, harvesting in a mature period to obtain the millet germplasm, measuring agronomic characters of the millet germplasm, calculating a high temperature resistance membership function value and an average value, carrying out clustering analysis, and then judging the high temperature resistance grade of the millet germplasm. According to the method, high-temperature stress treatment is carried out in the booting-heading stage and / or the flowering stage of the millet, the high-temperature-resistant grade of the millet germplasm can be identified and the high-temperature-resistant germplasm can be screened out by measuring the agronomic character membership function value of the millet in the mature stage and carrying out clustering analysis, and the method is simple, efficient, high in repeatability, reliable in result and suitable for popularization and application. The method has an important application value in high-temperature-resistant breeding of millet.

Description

Technical Field

[0001] The invention relates to the technical field of millet stress resistance identification, and in particular to an identification method and application of millet high temperature resistant germplasm. Background Art

[0002] Millet, a plant of the genus Setaria in the subfamily Millet of the Poaceae family, is one of the main grain crops in my country. It has the characteristics of short growth period, strong drought resistance, wide adaptability, storage resistance and dual-purpose use as food and feed. It is an important crop for sustainable dryland agriculture and structural adjustment of planting industry and a strategic reserve crop for responding to climate change. Millet after shelling is rich in nutrition and good palatability. It contains a variety of vitamins, proteins, fats, carbohydrates, and nutrients necessary for the human body such as calcium, phosphorus, and iron. Its nutritional components are in a suitable proportion, and it has antioxidant and spleen and stomach strengthening effects. It is a good food nutrition source with high nutritional value, which meets the needs of the dietary structure of Chinese residents and is an indispensable food for improving dietary diversity and promoting people's health.

[0003] With the continuous warming of the global climate in recent years, the intensity, frequency and duration of high temperature heat damage have increased, becoming a major threat to agricultural production. As a traditional crop with strong stress resistance, the yield and quality of millet have also been affected by extreme high temperature weather. High temperature stress affects the yield formation of millet, reduces the chlorophyll content of millet, reduces the transport of millet assimilates to the ear, and increases the accumulation of oxidative damage substances in millet. Screening and cultivating high temperature resistant millet germplasm is one of the effective ways to solve the losses caused by high temperature stress. Among them, high temperature resistance identification is the basis for the evaluation and utilization of millet high temperature resistant germplasm resources. However, the current identification methods of millet high temperature resistant germplasm are not standardized, the evaluation system is not unified, and there is a phenomenon that the identification results are difficult to repeat. It is urgent to establish an efficient, accurate and standardized millet high temperature resistance identification technology system.

[0004] Based on this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide an identification method and application of millet heat-resistant germplasm, so as to solve the problems in the prior art that the identification method of millet heat-resistant germplasm is not standardized, the evaluation system is not unified, and the identification results are difficult to repeat.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A method for identifying high temperature resistant millet germplasm comprises the following steps:

[0008] (1) Planting millet seeds, subjecting them to high temperature stress during the growth period, and harvesting them at maturity to obtain millet germplasm;

[0009] (2) measuring the agronomic traits of millet germplasm, calculating the high temperature resistance membership function values ​​of all millet germplasm agronomic traits and the average value of the high temperature resistance membership function value of each millet germplasm agronomic trait;

[0010] (3) Perform cluster analysis on the average value of the high temperature resistance membership function value, and judge the high temperature resistance level of millet germplasm based on the average value of the high temperature resistance membership function value and the cluster analysis results.

[0011] Preferably, the millet seeds described in step (1) are varieties suitable for planting in the summer millet region of North China;

[0012] The millet seeds include one or more of excellent germplasm resources, local germplasm, stable new strains and promoted varieties.

[0013] Preferably, the growth period in step (1) is the booting-heading period and / or the flowering period.

[0014] Preferably, the temperature of the high temperature stress in step (1) is 38-42°C.

[0015] Preferably, the agronomic traits described in step (2) include one or more of plant height, fruit setting rate, 1000-grain weight, ear grain weight and aboveground biomass.

[0016] Preferably, the calculation method of the high temperature resistant membership function value described in step (2) is:

[0017] When the agronomic traits are positively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=T-Tmin / Tmax-Tmin; when the agronomic traits are negatively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=1-(T-Tmin / Tmax-Tmin);

[0018] Where T is the average value of the measured values ​​of agronomic traits of millet germplasm, Tmax is the maximum value of agronomic traits of all millet germplasm, and Tmin is the minimum value of agronomic traits of all millet germplasm.

[0019] Preferably, the software used for the cluster analysis in step (3) is SPASS software.

[0020] Preferably, the method for determining the high temperature resistance grade in step (3) is as follows:

[0021] When the average value of the high temperature resistance membership function value is ≥0.70, the high temperature resistance grade is 1;

[0022] When the average value of the high temperature resistance membership function value is ≥0.60 and <0.70, the high temperature resistance grade is 2;

[0023] When the average value of the high temperature resistance membership function value is ≥0.57 and <0.60, the high temperature resistance grade is 3;

[0024] When the average value of the high temperature resistance membership function is ≥0.53 and <0.57, the high temperature resistance grade is 4;

[0025] When the average value of the high temperature resistance membership function value is ≥0.40 and <0.53, the high temperature resistance grade is 5;

[0026] When the average value of the high temperature resistance membership function is less than 0.40, the high temperature resistance grade is 6.

[0027] The invention provides application of the identification method in breeding of millet high temperature resistant germplasm.

[0028] The present invention has the following technical effects and advantages:

[0029] The present invention provides an identification method for high temperature resistant millet germplasm and application thereof. According to the method of the present invention, high temperature stress treatment is carried out during the heading stage and / or flowering stage of millet, and the membership function values ​​of agronomic traits at the maturity stage of millet are measured and cluster analysis is performed, so that the high temperature resistance grade of the millet germplasm can be identified and the high temperature resistant germplasm can be screened out. The method is simple, efficient and repeatable, and the result is reliable, and the method has important application value in the high temperature resistance breeding of millet. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The cluster analysis dendrogram is the average value of the membership function values ​​of the five traits. The vertical axis in the figure is the number of different varieties, a total of 28 varieties, and the horizontal axis is the Euclidean distance in the cluster analysis dendrogram;

[0031] Figure 2 This is the dendrogram of the cluster analysis of the membership function value of the fruiting rate. The vertical axis in the figure is the number of different varieties, a total of 28 varieties, and the horizontal axis is the Euclidean distance in the dendrogram of the cluster analysis;

[0032] Figure 3 This is an analysis chart of the results of identifying millet high temperature resistant germplasm using two methods. DETAILED DESCRIPTION

[0033] The present invention provides a method for identifying high temperature resistant millet germplasm, comprising the following steps:

[0034] (1) Planting millet seeds, subjecting them to high temperature stress during the growth period, and harvesting them at maturity to obtain millet germplasm;

[0035] (2) measuring the agronomic traits of millet germplasm, calculating the high temperature resistance membership function values ​​of all millet germplasm agronomic traits and the average value of the high temperature resistance membership function value of each millet germplasm agronomic trait;

[0036] (3) Perform cluster analysis on the average value of the high temperature resistance membership function value, and judge the high temperature resistance level of millet germplasm based on the average value of the high temperature resistance membership function value and the cluster analysis results.

[0037] In the present invention, the millet seeds described in step (1) are varieties suitable for planting in the summer millet region of North China;

[0038] The millet seeds include one or more of excellent germplasm resources, local germplasm, stable new strains and promoted varieties;

[0039] The millet seeds are preferably Yugu101, Zhenggu678, Jingshan T19-2, Zheng 22H3146, Zhonggu855, Jizajinmiao 4, Yugu18, Jinggu 4, Jigu168, Jigu33, Heng 2022-1, K281-2H, Luoyou6158, Zheng 22C1-3, Zheng 21H4109, Zheng 22C17, Yugu47, Yugu35, Yugu58, Zhengnonggu10, Jingshan 20T-1129, An 20h-v7020, Zheng 22C5, Luohong 22-1, Jingshan 20T-1829, Zheng 21Z3976, Yugu27 and Yugu29.

[0040] In the present invention, the growth period in step (1) is the booting-heading period and / or the flowering period;

[0041] The booting-heading period is from July 10 to July 28;

[0042] The flowering period is from July 25 to August 3.

[0043] In the present invention, the temperature of the high temperature stress in step (1) is 38-42°C, preferably 40°C.

[0044] In the present invention, the agronomic traits described in step (2) include one or more of plant height, fruit setting rate, 1000-grain weight, ear grain weight and aboveground biomass.

[0045] In the present invention, the calculation method of the high temperature resistant membership function value described in step (2) is:

[0046] When the agronomic traits are positively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=T-Tmin / Tmax-Tmin; when the agronomic traits are negatively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=1-(T-Tmin / Tmax-Tmin);

[0047] Where T is the average value of the measured values ​​of agronomic traits of millet germplasm, Tmax is the maximum value of agronomic traits of all millet germplasm, and Tmin is the minimum value of agronomic traits of all millet germplasm.

[0048] In the present invention, the software used for cluster analysis in step (3) is SPASS software.

[0049] In the present invention, the method for determining the high temperature resistance grade in step (3) is as follows:

[0050] When the average value of the high temperature resistance membership function value is ≥0.70, the high temperature resistance grade is 1, and the high temperature resistance is extremely strong;

[0051] When the average value of the high temperature resistance membership function value is ≥0.60 and <0.70, the high temperature resistance grade is 2 and the high temperature resistance is strong;

[0052] When the average value of the high temperature resistance membership function value is ≥0.57 and <0.60, the high temperature resistance grade is 3 and the high temperature resistance is resistant;

[0053] When the average value of the high temperature resistance membership function value is ≥0.53 and <0.57, the high temperature resistance grade is 4 and the high temperature resistance is medium;

[0054] When the average value of the high temperature resistance membership function value is ≥0.40 and <0.53, the high temperature resistance grade is 5 and the high temperature resistance is sensitive;

[0055] When the average value of the high temperature resistance membership function value is less than 0.40, the high temperature resistance grade is 6, and the high temperature resistance is extremely sensitive.

[0056] The invention provides application of the identification method in breeding of millet high temperature resistant germplasm.

[0057] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0058] The Yugu 101, Zhenggu 678, Jingshan T19-2, Zheng 22H3146, Zhonggu 855, Jizajinmiao 4, Yugu 18, Jinggu 4, Jigu 168, Jigu 33, Heng 2022-1, K281-2H, Luoyou 6158, Zheng 22C1-3, Zheng 21H4109, Zheng 22C17, Yugu 47, Yugu 35, Yugu 58, Zhengnonggu 10, Jingshan 20T-1129, An 20h-v7020, Zheng 22C5, Luohong 22-1, Jingshan 20T-1829, Zheng 21Z3976, Yugu 27 and Yugu 29 described in the embodiments are commercially available.

[0059] Example 1

[0060] Identification of high temperature resistance of millet germplasm by field experiment

[0061] Seed materials: 28 summer-sown millet germplasm resources with the same growth period were selected, namely Yugu101, Zhenggu678, JingshanT19-2, Zheng22H3146, Zhonggu855, Jizajinmiao4, Yugu18, Jinggu4, Jigu168, Jigu33, Heng2022-1, K281-2H, Luoyou6158, Zheng22C1-3, Zheng21H4109, Zheng22C17, Yugu47, Yugu35, Yugu58, Zhengnonggu10, Jingshan20T-1129, An20h-v7020, Zheng22C5, Luohong22-1, Jingshan20T-1829, Zheng21Z3976, Yugu27 and Yugu29. The heading period of the 28 millet germplasm resources was concentrated from July 17 to July 28.

[0062] Experimental location: Henan Modern Agriculture Research and Development Base (Xinxiang, Henan).

[0063] Experimental time: June to September 2022.

[0064] Experimental methods:

[0065] (1) Seeds of 28 millet germplasm resources with heading periods concentrated between July 17 and July 28 were sown at the Henan Modern Agriculture Research and Development Base. The sowing time was June 4, 2022. From July 17 to July 28, artificial high-temperature facilities were built to subject millet plants to high-temperature stress. The temperature was controlled between 38 and 42°C. The high-temperature stress time was from 10:00 a.m. to 3:00 p.m., and the temperature at other times was the same as the natural temperature. Six plants were selected from each germplasm and labeled. They were cultured to maturity and the seeds of the labeled germplasm were harvested.

[0066] (2) Five agronomic traits, namely plant height, fruiting rate, 1000-grain weight, ear-grain weight, and aboveground biomass, were measured for 28 millet germplasms at maturity. The high temperature resistance membership function values ​​of the five agronomic traits of all millet germplasms and the average value of the high temperature resistance membership function value of each millet germplasm agronomic trait were measured. The calculation method of the high temperature resistance membership function value is as follows:

[0067] When the agronomic traits are positively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=T-Tmin / Tmax-Tmin; when the agronomic traits are negatively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=1-(T-Tmin / Tmax-Tmin);

[0068] Where T is the average value of the measured values ​​of agronomic traits of millet germplasm, Tmax is the maximum value of agronomic traits of all millet germplasm, and Tmin is the minimum value of agronomic traits of all millet germplasm.

[0069] Among the five agronomic traits of plant height, fruit setting rate, 1000-grain weight, ear weight, and aboveground biomass, fruit setting rate, 1000-grain weight, ear weight, and aboveground biomass were positively correlated with high temperature resistance, and the calculation formula of their high temperature resistance membership function value was T(μ)=T-Tmin / Tmax-Tmin; when plant height was negatively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value was T(μ)=1-(T-Tmin / Tmax-Tmin);

[0070] Five agronomic traits, including plant height, fruit setting rate, 1000-grain weight, ear grain weight and aboveground biomass, were measured for 168 millet plants from 28 millet germplasms. The results showed that the maximum plant height was 159.4 cm, and the minimum was 81.2 cm; the maximum fruit setting rate was 0.99, and the minimum was 0.16; the maximum 1000-grain weight was 3.30 g, and the minimum was 1.47 g; the maximum ear grain weight was 22.14 g, and the minimum was 1.71 g; the maximum aboveground biomass was 46.7 g, and the minimum was 15.7 g.

[0071] According to the agronomic trait values ​​of plant height, fruit setting rate, 1000-grain weight, ear weight, and aboveground biomass of 28 millet germplasms totaling 168 millet plants, the average values ​​of plant height, fruit setting rate, 1000-grain weight, ear weight, and aboveground biomass of each millet germplasm, the high temperature resistance membership function value of the agronomic traits of millet germplasm, and the average value of the high temperature resistance membership function value of each millet germplasm were calculated. The results are shown in Table 1. Table 1 High temperature resistance membership function values ​​of 5 agronomic traits of 28 millet germplasms and the average value of the high temperature resistance membership function value of each millet germplasm

[0072]

[0073]

[0074]

[0075]

[0076] (3) Based on the average values ​​of the membership function values ​​of the five traits of each millet germplasm, cluster analysis was performed using SPASS software to obtain the cluster analysis diagram of 28 millet germplasms, as shown in the figure below: Figure 1 As shown, according to Figure 1 The high temperature resistance of 28 millet germplasms was divided into 6 levels, namely, high temperature resistance level 1, level 2, level 3, level 4, level 5 and level 6. The evaluation criteria for high temperature resistance level are shown in Table 2.

[0077] Table 2 Evaluation criteria for high temperature resistance grades

[0078] High temperature resistance grade The average of the membership function values ​​of the five traits High temperature resistance Level 1 ≥0.70 Very strong Level 2 ≥0.60 and <0.70 powerful Level 3 ≥0.57 and <0.60 High temperature resistance Level 4 ≥0.53 and <0.57 medium Level 5 ≥0.40 and <0.53 sensitive Level 6 ＜0.40 Extremely sensitive

[0079] According to the standards in Table 2, 12 germplasms with heat resistance levels of 1, 2 and 3 were screened out, among which Zheng 22C17 had an average membership function value of 0.7, heat resistance level of 1, and extremely strong heat resistance; Yugu 101, Zheng 22C5 and Jingshan T19-2 had average membership function values ​​of 0.625, 0.622 and 0.619, heat resistance level of 2, and strong heat resistance; Zheng 22H3146, Zhonggu 855, Jinggu 4, Yugu 35, Zheng 21H4109, Zheng 21Z3976, Heng 2022-1 and Zhengnonggu 10 had average membership function values ​​of 0.594, 0.597, 0.598, 0.585, 0.579, 0.597, 0.570 and 0.571, heat resistance level of 3, and heat resistance of resistant.

[0080] Example 2

[0081] Indoor test to identify the high temperature resistance of millet germplasm

[0082] Experimental location: Glass greenhouse

[0083] Using high temperature identification in a glass greenhouse, the average daily temperature of the greenhouse was set at 33-35°C. On June 4, 2022, potted treatment was adopted to plant 28 millet germplasm seeds from the same batch in Example 1, and 6 pots were sown for each millet germplasm. From July 17 to July 28, the greenhouse was set with a maximum temperature of 42°C and a minimum temperature of 38°C from 10:00 am to 3:00 pm every day. The seeds were cultivated to maturity and harvested. Five agronomic traits of 28 millet germplasms at maturity, including plant height, fruit setting rate, 1000-grain weight, ear grain weight, and aboveground biomass, were measured. The high temperature resistance membership function values ​​of all five agronomic traits of millet germplasms and the average value of the high temperature resistance membership function value of each millet germplasm were measured. Based on the average value of the membership function values ​​of the five traits of each millet germplasm, cluster analysis was performed using SPASS software, and the high temperature resistance of the 28 millet germplasms was divided into 6 levels, namely high temperature resistance level 1, level 2, level 3, level 4, level 5 and level 6. Then, according to the evaluation criteria of high temperature resistance level, 12 germplasms with high temperature resistance levels 1, 2 and 3 were screened out, namely, Zheng 22C17 with high temperature resistance level 1, and extremely strong high temperature resistance; Yugu 101, Zheng 22C5 and Jingshan T19-2 with high temperature resistance level 2, and strong high temperature resistance; Zheng 22H3146, Zhonggu 855, Jinggu No. 4, Yugu 35, Zheng 21H4109, Zheng 21Z3976, Heng 2022-1 and Zhengnonggu No. 10 with high temperature resistance level 3, and high temperature resistance.

[0084] Comparative Example 1

[0085] Single trait identification method

[0086] Seed materials: 28 millet germplasm resources from the same batch as in Example 1.

[0087] Experimental location: Henan Modern Agriculture Research and Development Base (Xinxiang, Henan).

[0088] Experimental time: June to September 2022.

[0089] Experimental methods:

[0090] (1) Seeds of 28 millet germplasm resources with a concentrated heading period from July 17 to July 28 were sown at the Henan Modern Agriculture Research and Development Base. The sowing time was June 4, 2022. From July 17 to July 28, high-temperature facilities were artificially built to subject millet plants to high-temperature stress. The temperature was controlled between 38 and 42°C. The high-temperature stress time was from 10:00 a.m. to 15:00 p.m., and the temperature at other times was the same as the natural temperature. Six plants were selected from each germplasm and labeled. They were cultured to maturity, and the seeds of the labeled germplasm were harvested. The fruit set rate of the 28 millet germplasm plants at maturity was measured, and the high-temperature resistance membership function values ​​of the fruit set rate of all millet germplasms were measured. System cluster analysis was performed with the fruit set rate as the only indicator, as shown in the following figure. Figure 2 As shown, according to Figure 2 The high temperature resistance of 28 millet germplasms was divided into 6 levels, namely, high temperature resistance level 1, level 2, level 3, level 4, level 5 and level 6. The evaluation criteria for high temperature resistance level are shown in Table 3.

[0091] Table 3 Evaluation criteria for high temperature resistance grades

[0092]

[0093]

[0094] According to the evaluation criteria in Table 3, 17 high-temperature-resistant germplasms with high-temperature resistance levels of 1, 2 and 3 were screened out, namely Zhenggu 678, Zheng 22H3146, Jinggu 4, Heng 2022-1, Zheng 22C17, Yugu 35, Zhengnonggu 10, Zheng 22C5, Luohong 22-1, Zheng 21Z3976, Yugu 29, Jingshan T19-2, Yugu 27, Jigu 33, Yugu 58, Zhonggu 855 and Jingshan 20T-1829.

[0095] Experimental Example 1: Comparative Analysis of Screening Results and Efficiency of Different Identification Methods

[0096] By comparing the results of screening germplasm in Example 1 and Example 2, it is known that the identification method of millet high temperature resistant germplasm provided by the present invention has good repeatability.

[0097] By comparing the results of the single trait identification method of fruit set rate in comparative example 1 and the identification method in embodiment 1, the results are as follows: Figure 3As shown, it was found that the two methods screened out 12 and 17 heat-resistant germplasms, respectively, of which 10 were the same germplasms, namely Jingshan T19-2, Zheng 22H3146, Jinggu No. 4, Heng 2022-1, Zheng 22C17, Yugu 35, Zheng 22C5, Zheng 21Z3976, Zhonggu 855 and Zhengnonggu No. 10, accounting for 83.3% and 58.8% of the total germplasm, respectively. This shows that the identification results of the method in Example 1 have good overlap, the identification method is accurate and reliable, and can be used as one of the identification and screening methods for heat-resistant millet germplasm.

[0098] Experimental Example 2: Breeding and Utilization of High Temperature Tolerant Millet Germplasm

[0099] The high temperature-resistant millet germplasms Zheng 22C17 and Yu Gu 101 identified by the method of the present application were hybridized with high temperature-sensitive germplasms Ji Gu 168, Yu Gu 18 and other materials to create a batch of F4 populations, including 500 plant lines, which were sown on June 5, 2024. Most plant lines suffered moderate high temperature stress during the heading and flowering stages (heading period July 22 to July 29, flowering period July 25 to August 2). The identification method of the present invention was used to screen high temperature-resistant germplasms, and the high temperature resistance during the heading and flowering stages was directly identified in the field. 500 millet lines were harvested at maturity, and finally 45 high temperature-resistant excellent millet germplasms were screened.

[0100] As can be seen from the above embodiments, the present invention provides a method for identifying millet high temperature resistant germplasm and its application. According to the method of the present invention, high temperature stress treatment is carried out at the millet heading stage and / or flowering stage, and the high temperature resistance grade of millet germplasm can be identified by measuring the membership function value of agronomic traits at the maturity stage of millet and performing cluster analysis, and high temperature resistant germplasm can be screened out. The method is simple, efficient, repeatable, and reliable in results, and has important application value in millet high temperature resistant breeding.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for identifying high temperature resistant millet germplasm, characterized in that: The steps include: (1) Planting millet seeds, subjecting them to high temperature stress during the growth period, and harvesting them at maturity to obtain millet germplasm; (2) measuring the agronomic traits of millet germplasm, calculating the high temperature resistance membership function values ​​of all millet germplasm agronomic traits and the average value of the high temperature resistance membership function value of each millet germplasm agronomic trait; (3) Perform cluster analysis on the average value of the high temperature resistance membership function value, and judge the high temperature resistance level of millet germplasm based on the average value of the high temperature resistance membership function value and the cluster analysis results.

2. The identification method according to claim 1, characterized in that: The millet seeds described in step (1) are varieties suitable for planting in the summer millet region of North China; The millet seeds include one or more of excellent germplasm resources, local germplasm, stable new strains and promoted varieties.

3. The identification method according to claim 1, characterized in that: The growth period described in step (1) is the booting-heading period and / or the flowering period.

4. The identification method according to claim 1, characterized in that: The temperature of the high temperature stress described in step (1) is 38-42°C.

5. The identification method according to claim 1, characterized in that: The agronomic traits described in step (2) include one or more of plant height, fruit setting rate, thousand-grain weight, ear grain weight and aboveground biomass.

6. The identification method according to claim 1, characterized in that: The calculation method of the high temperature resistance membership function value described in step (2) is: When the agronomic traits are positively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=T-Tmin / Tmax-Tmin; when the agronomic traits are negatively correlated with high temperature resistance, the calculation formula of the high temperature resistance membership function value is T(μ)=1-(T-Tmin / Tmax-Tmin); Where T is the average value of the measured values ​​of agronomic traits of millet germplasm, Tmax is the maximum value of agronomic traits of all millet germplasm, and Tmin is the minimum value of agronomic traits of all millet germplasm.

7. The identification method according to claim 1, characterized in that: The software used for the cluster analysis in step (3) is SPASS software.

8. The identification method according to claim 1, characterized in that: The method for determining the high temperature resistance level in step (3) is as follows: When the average value of the high temperature resistance membership function value is ≥0.70, the high temperature resistance grade is 1; When the average value of the high temperature resistance membership function value is ≥0.60 and <0.70, the high temperature resistance grade is 2; When the average value of the high temperature resistance membership function value is ≥0.57 and <0.60, the high temperature resistance grade is 3; When the average value of the high temperature resistance membership function is ≥0.53 and <0.57, the high temperature resistance grade is 4; When the average value of the high temperature resistance membership function value is ≥0.40 and <0.53, the high temperature resistance grade is 5; When the average value of the high temperature resistance membership function is less than 0.40, the high temperature resistance grade is 6.

9. Use of the identification method according to any one of claims 1 to 8 in breeding of millet germplasm resistant to high temperature.

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