Method for identifying salt tolerance of asparagus in whole growth period in coastal saline-alkali land

Abstract

The invention belongs to the technical field of plant breeding, and particularly relates to a method for identifying salt tolerance of asparagus in the whole growth period in coastal saline-alkali soil. According to the method, the salt tolerance of the variety is identified in the germination period, the seedling period and the field growth period of the asparagus, so that the salt tolerance of the whole growth period of the asparagus is comprehensively evaluated. In the germination period and the seedling period of the asparagus, a traditional sodium chloride stress method is changed into a saline-alkali soil leaching solution for salt stress treatment. According to the method, the salt tolerance of the asparagus varieties is evaluated by adopting a fuzzy comprehensive evaluation method in the field growth period of the asparagus, the contribution rates of a plurality of phenotype indexes under salt stress are comprehensively considered, the salt tolerance correction membership function value of each variety is calculated, and the limitation of evaluation by a single character index is avoided. According to the method, the salt tolerance of the variety can be reflected more comprehensively and more accurately from different growth periods of the asparagus.

Description

Technical Field

[0001] The present application belongs to the technical field of plant breeding, and specifically relates to a method for identifying the salt tolerance of asparagus during the entire growth period for use in coastal saline-alkali land. Background Art

[0002] Soil salinization is one of the main stress factors that restrict plant growth. According to statistics, the area of ​​various saline-alkali soils in the world is about 800 million hectares, accounting for 6% of the world's total land area. In China, 100 million hectares of land are affected by salt damage. Fully developing and utilizing saline-alkali land is an important direction of current agricultural research. Screening and cultivating salt-tolerant crops and salt-tolerant varieties of crops is one of the most direct and effective ways to fully utilize saline-alkali land. Asparagus (Asparagus officinalis L.) has a strong salt-alkali tolerance and can grow normally on moderately and lightly saline-alkali land with a soil salt content of less than 0.3%, but its growth is inhibited on saline-alkali land with a soil salt content of more than 0.4%, and there are large differences in salt tolerance among different varieties. Therefore, the identification of salt tolerance of asparagus germplasm resources and the screening of salt-tolerant germplasm are of great significance for the selection and breeding of asparagus salt-tolerant varieties, the study of salt tolerance mechanisms, and the promotion of asparagus cultivation in saline-alkali land.

[0003] In recent years, domestic and foreign scholars have carried out a lot of work in the identification of plant salt tolerance, and have evaluated the salt tolerance and screened the identification indicators of many crop germplasm resources such as wheat, soybean, sorghum, and cotton, and have achieved certain results. However, the research on salt tolerance of asparagus is still in its initial stage, and the depth and breadth of salt tolerance germplasm identification and evaluation are relatively backward. At present, most crop salt tolerance evaluations are based on the identification of the bud or seedling stage. Although the identification results of the bud and seedling stages can be used as reference indicators for the salt tolerance of asparagus, there are differences in salt tolerance at different developmental stages of crops. If the selected salt-tolerant varieties are applied to actual production, the salt tolerance identification of the whole growth period must be carried out in the field that is closer to the actual field production. If the identification of the germination period, seedling stage and field growth period is combined to screen for salt tolerance during the whole growth period, the results will be more reliable.

[0004] A Chinese patent with announcement number CN104472059B discloses a method for identifying the salt tolerance of asparagus. It uses artificially prepared seawater of a specific concentration to stress asparagus during the bud and seedling stages, investigates agronomic traits such as germination potential, germination index, vitality index, radicle length during the bud stage, plant height during the seedling stage, number of stems, stem diameter, fresh root mass, dry root mass, and root volume, calculates the salt tolerance coefficient of each trait, calculates the comprehensive salt tolerance value of each variety, and identifies the salt tolerance of different asparagus varieties based on the size of the comprehensive salt tolerance value. A Chinese patent with announcement number CN109380072A discloses a method for seed cultivation before planting asparagus in saline-alkali land. When cultivating salt-tolerant seeds, the asparagus. However, both of the above methods use sodium chloride solution for stress treatment. Although the main salt in saline-alkali soil is sodium chloride, there are also carbonates, bicarbonates, sulfates, and ca in the soil. 2+ 、mg 2+ The salt content is the same as that of other plants. During the growth process, the various components work synergistically with each other, so it cannot accurately reflect the salt tolerance of asparagus in the saline-alkali land growth environment.

[0005] In view of the problems in the prior art of evaluating the salt tolerance of asparagus, such as unreasonable configuration of the salt stress treatment solution and incomplete evaluation of the growth stage, the present application proposes a method for identifying the salt tolerance of asparagus during the entire growth period in coastal saline-alkali land. Summary of the invention

[0006] In view of the problems in the prior art of evaluating the salt tolerance of asparagus, such as unreasonable configuration of the salt stress treatment solution and incomplete evaluation of the growth stage, the present application proposes a method for identifying the salt tolerance of asparagus during the entire growth period in coastal saline-alkali land.

[0007] The specific scheme of this application is as follows:

[0008] A method for identifying salt tolerance of asparagus during the whole growth period for use in coastal saline-alkali land comprises the following steps:

[0009] Step S1. Identification of salt tolerance during the germination period of asparagus

[0010] Treat asparagus seeds with salt solution and water respectively, count the germination rates of asparagus seeds after being treated with salt solution and water respectively, calculate the relative salt damage rate, and determine the salt tolerance level of asparagus seeds according to the relative salt damage rate;

[0011] Step S2. Identification of salt tolerance of asparagus seedlings

[0012] The asparagus seeds were potted and cultured into asparagus seedlings, and the asparagus seedlings were transferred to hydroponic tanks for culture. Then, the asparagus seedlings were subjected to salt stress treatment, the salt damage level at the seedling stage was counted, and the salt damage index was calculated based on the salt damage level at the seedling stage, and the salt tolerance level of the asparagus seedling stage was determined based on the salt damage index;

[0013] Step S3. Identification of salt tolerance of asparagus during field growth

[0014] First, the asparagus seeds are potted and cultivated to the seedling stage and transplanted to saline-alkali land with a soil salt content greater than 0.5% and soil with a soil salt content less than 0.1% for cultivation, and then the cultivation is continued for not less than 50 days. Finally, the growth index of the asparagus is measured, and the salt tolerance coefficient of the growth index and the membership function value of the salt tolerance are calculated. The modified membership function value of the salt tolerance of the asparagus is calculated based on the fuzzy comprehensive evaluation method, and the salt tolerance grade of the asparagus variety during the growth period is determined according to the average value of the modified membership function value of the salt tolerance;

[0015] Step S4. Identification of salt tolerance of asparagus during the germination, seedling and field growth stages

[0016] The Venn diagram was used to detect the overlapping sets of salt tolerance of asparagus during germination, seedling and field growth periods, and asparagus varieties with strong salt tolerance throughout the growth period were screened out.

[0017] Preferably, the preparation process of the salt solution in step S1 is as follows: saline-alkali soil and distilled water are mixed and stirred in a mass ratio of 1:2, then filtered to obtain a soil extract, and the soil extract is diluted to a salt solution with a salt content of 10 g / L.

[0018] Preferably, the process of treating the asparagus seeds with the salt solution and the clean water respectively in step S1 is as follows:

[0019] Salt solution treatment: sterilize the asparagus seeds in ozone, and culture the asparagus seeds in a salt solution, the salt solution covers 1 / 4 of the asparagus seeds, and the culture temperature is 27°C;

[0020] Clean water treatment: sterilize the asparagus seeds in ozone, and culture them in clean water, with the clean water covering 1 / 4 of the asparagus seeds, and the culture temperature is 27°C.

[0021] Preferably, the calculation formula of the germination rate of asparagus seeds in step S1 is as follows:

[0022] Germination rate = (total number of seeds germinated in 12 days / number of seeds tested) × 100% (1).

[0023] Preferably, the relative salt damage rate of asparagus seeds in step S1 is calculated as follows:

[0024]

[0025] Preferably, the process of subjecting the asparagus seedlings to salt stress treatment in step S2 is as follows: diluting the soil extract to a salt content of 12 g / L, and then mixing it with an equal volume of Yamazaki nutrient solution as a culture solution for salt stress treatment, the culture temperature is 28° C. from 8 a.m. to 18 p.m., and 19° C. from 18 p.m. to 8 a.m. the next day, the light intensity is 40,000 Lux, and aeration is performed in the culture solution for 4 hours from 8 a.m. to 10 a.m. and from 3 p.m. to 5 p.m. every day using a ventilation pump.

[0026] Preferably, the calculation formula of the salt damage index in step S2 is as follows:

[0027]

[0028] Among them, N is the total number of seedlings, N0 is the number of seedlings with normal growth; N1 is the number of seedlings with normal growth symptoms, but yellowing and chlorosis symptoms on the top of the new stems; N2 is the number of seedlings with inhibited growth of all new stems, yellowing leaves, and a stem rate of less than 20%; N3 is the number of seedlings with symptoms of inhibited growth, yellowing of all above-ground leaves, and a stem rate of 20-60%; N4 is the number of seedlings with symptoms of death and a stem rate of more than 60%.

[0029] Preferably, the asparagus growth indicators measured in step S3 include plant height, stem diameter, stem number, bulb disk diameter, underground fresh weight, underground dry weight, root number, aboveground fresh weight and aboveground dry weight.

[0030] Preferably, the calculation formula of the salt tolerance coefficient in step S3 is as follows:

[0031]

[0032] Wherein, SCtg is the salt tolerance coefficient of trait t of genotype g, and Xtgst and Xtgck are the trait values ​​of trait t of genotype f in the salt treatment group and the control group, respectively.

[0033] Preferably, the calculation formula of the membership function value of salt tolerance in step S3 is as follows:

[0034]

[0035] Among them, Utg is the membership function value of the salt tolerance of trait t of genotype g, SCtmin and SCtmax are the minimum and maximum values ​​of the salt tolerance coefficient of trait t, respectively.

[0036] Preferably, the formulas for calculating the modified membership function value of salt tolerance and the average value of the modified membership function value of salt tolerance in step S3 are as follows:

[0037]

[0038] Among them, Ug is the average value of the membership function of all measured traits of the salt-tolerant genotype g, Ptg is the contribution rate of the trait t of each asparagus variety obtained by principal component analysis, and W is the average value of the modified membership function value of salt tolerance.

[0039] Beneficial effects of this application:

[0040] (1) The present application achieves a comprehensive assessment of the salt tolerance of asparagus throughout its entire growth period by identifying the salt tolerance of asparagus varieties during the germination period, seedling period, and field growth period. This multi-stage identification method can ensure that the selected varieties can exhibit good salt tolerance at all growth stages, thereby having higher adaptability and stability in actual production.

[0041] (2) The present application changes the traditional sodium chloride stress method to the use of saline-alkali soil extract for salt stress treatment during the germination and seedling stages of asparagus. This method is closer to the salinity conditions of the soil in actual production and can provide a more realistic simulation environment. In this way, the scientificity and practicality of salt tolerance evaluation are ensured.

[0042] (3) This application uses a fuzzy comprehensive evaluation method to evaluate the salt tolerance of asparagus varieties during the field growth period. This method calculates the modified membership function value of salt tolerance of each variety by comprehensively considering the contribution rate of multiple phenotypic indicators under salt stress. This multi-indicator comprehensive evaluation method avoids the limitation of relying solely on a single trait indicator for evaluation and can more comprehensively and accurately reflect the salt tolerance of the variety. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Attached Figure 1 This is a Venn diagram for the screening of salt tolerance of asparagus throughout its growth period for this application.

[0044] Explanation of the accompanying drawings: b, salt-tolerant varieties during the field growth period; a, salt-tolerant varieties during the seedling stage; c, salt-tolerant varieties during the germination stage. DETAILED DESCRIPTION

[0045] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of the present invention are described in detail below in combination with the preferred embodiments.

[0046] Example 1

[0047] This embodiment provides a method for identifying salt tolerance of asparagus during the germination period, which is as follows:

[0048] (1) Prepare salt solution

[0049] Take 3kg of saline-alkali soil from the coastal area, add 6kg of distilled water, stir thoroughly, first use double-layer gauze to filter coarsely, then use double-layer filter paper to filter, obtain clear soil extract, and measure the total salt content of the soil extract (mother liquor) to be 36g / L, i.e., 3.6% by mass. Take 200ml of the mother liquor, add 520mL of distilled water, mix well, and obtain a salt solution with a salt content of 10g / L, i.e., 1% by mass.

[0050] (2) Germination period culture

[0051] 1) Using 95 asparagus variety resources as materials, the 95 asparagus varieties are shown in Table 1. First, the asparagus seeds were sterilized in ozone for 30 minutes. 50 plump seeds of uniform size were selected from each variety and placed in a culture dish with 3 layers of filter paper with a diameter of 9 cm placed in advance, where the diameter of the culture dish was 10 mm.

[0052] 2) Three experimental groups and three control groups were set up for each asparagus variety. About 10 mL of a salt solution with a salt content of 10 g / L was added to the culture dishes of the experimental groups, with the amount of the salt solution covering 1 / 4 of the asparagus seeds. An equal amount of distilled water was added to the culture dishes of the control groups, and then the culture dishes were covered with lids and sealed with sealing film.

[0053] 3) The sealed culture dish was placed in an artificial climate box, and the culture temperature was set at 27°C. The culture was carried out for 12 days. The germination of asparagus seeds in the experimental group and the control group was checked and counted every day. The germination rate and relative salt damage rate of asparagus seeds were calculated. The formulas of germination rate and relative salt damage rate are shown in formula (1) and formula (2). The asparagus seeds were divided into 5 salt tolerance levels according to the relative germination rate, as shown in Table 2.

[0054] Germination rate = (total number of seeds germinated in 12 days / number of seeds tested) × 100% (1)

[0055]

[0056] Table 2 Classification of salt tolerance during asparagus germination period

[0057] Salt tolerance level at bud stage Relative salt damage rate (%) Highly salt tolerant (level 1) 0～20 Salt tolerance (level 2) 20.1～40 Moderate salt tolerance (level 3) 40.1～60 Salt sensitivity (level 4) 60.1～80 Highly sensitive (level 5) 80.1～100

[0058] Results Analysis

[0059] Combined with Table 1, it can be seen that the average germination rate of the test materials (water treatment) of 95 asparagus seeds under salt-free conditions was 95.05%, while the average value (47.71%) under salt stress conditions dropped by half. By comparison, it was found that the salt tolerance of asparagus during germination can be divided into three types. The first type is that the germination rate of asparagus seeds in the control group and the experimental group is relatively high, and the relative salt damage rate is less than 20%. There are 11 varieties in total, among which Jx1502, Jersey night and Ji08-2 have the strongest salt tolerance. The second type is that the germination rate of salt-treated seeds is much lower than that of asparagus seeds in the control group, and the relative salt damage rate is greater than 80%. Among them, the asparagus variety with the lowest salt tolerance is UC800, with a seed germination rate of 96.1% in the control group and only 12.6% in the experimental group. The third type accounts for the vast majority, with a relative salt damage rate between 20% and 80%. Through the identification of salt tolerance at the germination stage, the varieties Jx1502, Jersey night and Ji08-2 with high salt tolerance potential at the germination stage were screened.

[0060] Example 2

[0061] This embodiment provides a method for identifying salt tolerance of asparagus seedlings, which is as follows:

[0062] (1) Seedling cultivation

[0063] Asparagus seeds were sown and cultivated in plastic pots with a diameter of 15 cm, with one seedling planted in each plastic pot. The plastic pots were filled with a substrate with a volume ratio of vermiculite: peat = 4:3, and cultivated for 35 days.

[0064] (2) Hydroponic tank cultivation

[0065] After 35 days of cultivation, the seedlings were taken out of the plastic pots, the root substrate was washed with tap water, and the seedlings were transferred to a hydroponic tank (the size of the hydroponic tank was 100cm×50cm×20cm), and the hydroponic tank was covered with a foam board, and a planting hole with a diameter of 3cm to 4cm was set on the foam board. The planting hole density was 20cm×20cm, and there was one plant in each hole. The seedlings were fixed with a sponge strip. The nutrient solution was 1 / 2 dose of Yamazaki nutrient solution. The nutrient solution was aerated for 4 hours with an aeration pump at 8:00-10:00 a.m. and 15:00-17:00 p.m. every day, and the seedlings were cultured in the hydroponic tank until the 7th day.

[0066] (3) Salt stress treatment of asparagus plants cultured in hydroponic tanks for 7 days

[0067] 1) Preparation of culture solution for the hydroponic tank of the test group: The soil extract (mother solution) prepared in Example 1 was adjusted to a total salt content of 12 g / L with distilled water, and then mixed with an equal volume of the Yamazaki nutrient solution mother solution, and added to the hydroponic tank so that the volume of the solution in the hydroponic tank reached 2 / 3 of the volume of the hydroponic tank. Finally, the hydroponic tank contained 1 / 2 dose of the Yamazaki nutrient solution with a salt content of 6 g / L.

[0068] 2) Prepare the culture medium for the control group hydroponic tank: use 1 / 2 dose of Yamazaki nutrient solution without adding salt solution.

[0069] 3) Half of the seedlings were placed in the culture solution of the hydroponic tank of the experimental group as the experimental group; the other half were placed in the culture solution of the hydroponic tank of the control group as the control group. The asparagus plants were cultured in an artificial climate chamber at a temperature of 28°C during the day (8:00 to 18:00) and 19°C at night (18:00 to 8:00 the next day), with a light intensity of 40,000 Lux. The nutrient solution was aerated for 4 hours from 8:00 to 10:00 and from 15:00 to 17:00 every day, and the seedlings were cultured in the hydroponic tank until the 7th day. The salt tolerance phenotype of the seedling stage was counted, and the classification of the salt tolerance phenotype of the seedling stage was shown in Table 2. The salt damage index was calculated, and the calculation formula of the salt damage index was shown in Formula (3). The salt tolerance level of the seedling stage was divided according to the salt damage index as shown in Table 3, and the variety resources of salt tolerance or salt sensitivity at the seedling stage were screened.

[0070]

[0071] Among them, N is the total number of seedlings, N0 is the number of seedlings at level 0; N1 is the number of seedlings at level 1; N2 is the number of seedlings at level 2; N3 is the number of seedlings at level 3; N4 is the number of seedlings at level 4;

[0072] Table 2 Phenotypic classification of salt tolerance at the seedling stage

[0073]

[0074] Table 3 Classification of salt tolerance at seedling stage

[0075] Salt tolerance level at seedling stage Salt damage index (%) Highly salt tolerant (level 1) 0～20 Salt tolerance (level 2) 20.1～40 Moderate salt tolerance (level 3) 40.1～60 Salt sensitivity (level 4) 60.1～80 Highly sensitive (level 5) 80.1～100

[0076] Results Analysis

[0077] In the comprehensive evaluation of salt tolerance at the seedling stage of 95 asparagus varieties (Appendix 1), 5 varieties were grade 1 (highly salt-tolerant), 14 were grade 2 (salt-tolerant), 27 were grade 3 (medium salt-tolerant), 38 were grade 4 (salt-sensitive), and 11 were grade 5 (highly sensitive), accounting for 3.5%, 12.8%, 45.3%, 33.7%, and 4.7% of the total number of tested materials, respectively. Seedling salt-sensitive varieties (grades 4 and 5) accounted for more than half of the tested materials (51.6%), and 18 varieties were salt-tolerant at the seedling stage (grades 1 and 2), accounting for only 18.9%. Five varieties with grade 1 salt tolerance at the seedling stage were identified, namely Jersey night, Mondeo, Ji08-2, Fo5030215, and Granno. Among them, the salt damage index of "Ji08-2" was 0, and all seedlings had no obvious symptoms of damage. Diamonds, Green spears, Wei2014-2 and Imperial varieties all died 7 days after salt treatment, indicating that their salt tolerance was the worst at the seedling stage.

[0078] Example 3

[0079] This embodiment provides a method for identifying salt tolerance of reeds during the field growth period, which is as follows:

[0080] (1) 95 asparagus varieties were conventionally raised for seedlings. In May 2020, when the seedlings were 50 days old (two above-ground stems and quasi-leaves were developed), the 95 asparagus varieties were transplanted to the saline-alkali land in Xiaoshan Town, Haixing County, Cangzhou City, Hebei Province (117.20°N, 37.56°E). The seedlings of each variety were divided into two parts, one part was transplanted to the saline-alkali land with a total soil salt content of 0.79%, and the other part was transplanted to the control land with a total soil salt content of 0.07%. They were cultivated for 90 days. The experimental design was a two-factor block design with three replications. Salt treatment was the main factor and genotype was the secondary factor. The soil composition and pH of saline-alkali soil and control soil are shown in Table 4. The row spacing of asparagus field cultivation was 130 cm, the plant spacing was 30 cm, and 30 plants of each asparagus variety were planted repeatedly with conventional cultivation management.

[0081] Table 4 Soil composition and pH of saline-alkali soil and control soil

[0082]

[0083]

[0084] (2) In September 2020, nine parameters of 95 asparagus varieties were measured, including plant height, stem diameter, root disk diameter, number of stems, number of roots, aboveground fresh weight, aboveground dry weight, underground fresh weight, and underground dry weight.

[0085] (3) The salt tolerance coefficient (SCtg) and the membership function value (Utg) of the nine indicators of each variety were calculated respectively. Finally, the fuzzy comprehensive evaluation method was used to calculate the modified membership function value (Ug) of salt tolerance of each variety through the contribution rate of the nine indicators. The salt tolerance of each asparagus variety was divided into five levels according to the average value (W) of the modified membership function value, as shown in Table 5.

[0086] Table 5 Classification of salt tolerance during field growth period

[0087] The average value of the positive membership function Salt tolerance Ug≥W+1.64SD Highly salt tolerant W+1SD≤Ug <W+1.64SD Salt tolerance W-1SD≤Ug <W+1SD Moderate salt tolerance W-1.64SD≤Ug <W-1SD Salt sensitivity and <W-1.64SD Highly sensitive

[0088] The calculation formulas for the salt tolerance coefficient (SCtg), the membership function value of salt tolerance (Utg), the modified membership function value of salt tolerance (Ug) and the average value of the modified membership function value of salt tolerance (W) are as follows:

[0089]

[0090] Wherein, SCtg is the salt tolerance coefficient of trait t of genotype g, and Xtgst and Xtgck are the trait values ​​of trait t of genotype f in the salt treatment group and the control group, respectively.

[0091]

[0092] Among them, Utg is the membership function value of the salt tolerance of trait t of genotype g, SCtmin and SCtmax are the minimum and maximum values ​​of the salt tolerance coefficient of trait t, respectively.

[0093]

[0094] Among them, Ug is the average value of the membership function of all measured traits of the salt-tolerant genotype g, Ptg is the contribution rate of the trait t of each asparagus variety obtained by principal component analysis, and W is the average value of the modified membership function value.

[0095] Results Analysis

[0096] The results showed (Table 6) that the measured values ​​of the nine traits of asparagus were significantly reduced under salt stress. The results of variance analysis of 95 asparagus varieties showed that there were extremely significant differences in the nine traits under salt stress and control. Among them, the aboveground dry weight and aboveground fresh weight decreased by more than 60%, which was significantly different from other traits, indicating that these two traits were relatively sensitive to salt stress. Further variance analysis showed that there were significant differences between the SC (salt tolerance coefficient) of these two traits and other traits (P<0.05), indicating that these two traits were very sensitive to salt stress, while the decline rate of other traits compared with the control group was between 42% and 51%. In addition, there were significant differences between the genotypes of the nine traits of all asparagus varieties (P<0.001), and the interaction between the genotype of all traits and salt stress treatment was also significant.

[0097] The coefficient of genetic variation (CVg) values ​​for the nine investigated traits ranged from 13.34% to 39.84% (Table 7). The CVg values ​​for stem number, aboveground dry weight, and aboveground fresh weight were over 30%, namely 39.84%, 38.94%, and 30.44%, respectively. For the other six traits, the CVg values ​​ranged from 13.34% to 29.28%. These results indicated that there was significant genotypic variation in the traits studied among the 95 accessions under the two salinity conditions. The broad-sense heritability (H2) values ​​for the nine investigated traits were analyzed and ranged from 0.36 to 0.82, indicating that these traits were stable and suitable for application in the evaluation system.

[0098] Ug (modified membership function value of salt tolerance) reflects the strength of salt tolerance. Among the 95 asparagus varieties, 18 varieties had Ug values ​​between 0.62 and 0.84, including 7 (Apllo, Ji08-2, Jx1502, TC, Champion, C9-12 and NJ800) highly salt-tolerant varieties and 11 salt-tolerant varieties (Welcom, Atlas, Franklim, NJ1191, etc.). In contrast, 15 varieties had Ug values ​​between 0.19 and 0.32 and were classified as salt-sensitive varieties, indicating that these asparagus germplasms are not suitable for planting in saline soils. The remaining 62 materials were considered to have moderate salt tolerance, with Ug values ​​between 0.33 and 0.61.

[0099] Table 6 Effects of salt stress on different traits of 95 varieties during field growth

[0100]

[0101] Table 7 Results of variance analysis of salt tolerance of 95 varieties during field growth period

[0102]

[0103]

[0104] Example 4

[0105] This embodiment provides a comprehensive full-growth period identification method for salt tolerance of asparagus during the germination period, seedling period and field growth period, as follows:

[0106] After evaluating the salt tolerance of 95 asparagus accessions at each growth stage, we obtained some salt-tolerant germplasm resources, including both highly salt-tolerant and salt-tolerant germplasms, which have high potential for further application in saline soil and breeding. Among them, there are 30 asparagus varieties with salt tolerance at the germination stage, 19 asparagus varieties with salt tolerance at the seedling stage, and 18 asparagus varieties with salt tolerance during the field growth period. In order to further explore the relationship between the salt tolerance identified in the three stages of asparagus germination, seedling and field growth, a Venn diagram was constructed to detect the unique and overlapping sets of salt-tolerant germplasm resources at different stages, as shown in the attached figure. Figure 1 As shown, there were 6 asparagus varieties in the germination stage and seedling stage, 5 in the seedling stage and field growth stage, and 6 in the field growth stage and germination stage. Among these three stages, only two asparagus varieties (Ji08-2 and Jx1502) had strong salt tolerance in all three growth stages.

[0107] Appendix: Results of salt tolerance tests on 195 varieties at different growth stages

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for identifying salt tolerance of asparagus during the whole growth period for use in coastal saline-alkali land, characterized in that: The steps include: Step S1. Identification of salt tolerance during the germination period of asparagus Treat asparagus seeds with salt solution and water respectively, count the germination rates of asparagus seeds after being treated with salt solution and water respectively, calculate the relative salt damage rate, and determine the salt tolerance level of asparagus seeds according to the relative salt damage rate; Step S2. Identification of salt tolerance of asparagus seedlings The asparagus seeds were potted and cultured into asparagus seedlings, and the asparagus seedlings were transferred to hydroponic tanks for culture. Then, the asparagus seedlings were subjected to salt stress treatment, the salt damage level at the seedling stage was counted, and the salt damage index was calculated based on the salt damage level at the seedling stage, and the salt tolerance level of the asparagus seedling stage was determined based on the salt damage index; Step S3. Identification of salt tolerance of asparagus during field growth First, asparagus seeds are potted and cultivated to the seedling stage and transplanted to saline-alkali land with a soil salt content greater than 0.5% and soil with a soil salt content less than 0.1% for cultivation, and then the cultivation is continued for not less than 50 days. Finally, the growth index of the asparagus is measured, and the salt tolerance coefficient of the growth index and the membership function value of the salt tolerance are calculated. The modified membership function value of the salt tolerance of the asparagus is calculated based on the fuzzy comprehensive evaluation method, and the salt tolerance grade of the asparagus variety during the growth period is determined according to the average value of the modified membership function value of the salt tolerance; Step S4. Identification of salt tolerance of asparagus during the germination, seedling and field growth stages The Venn diagram was used to detect the overlapping sets of salt tolerance of asparagus during germination, seedling and field growth periods, and asparagus varieties with strong salt tolerance throughout the growth period were screened out.

2. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The preparation process of the salt solution in step S1 is as follows: saline-alkali soil and distilled water are mixed and stirred at a mass ratio of 1:2, and then filtered to obtain a soil extract, and the soil extract is diluted to a salt solution with a salt content of 10 g / L.

3. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The process of treating the asparagus seeds with the salt solution and the clean water in step S1 is as follows: Salt solution treatment: sterilize the asparagus seeds in ozone, and culture the asparagus seeds in a salt solution, the salt solution covers 1 / 4 of the asparagus seeds, and the culture temperature is 27°C; Clean water treatment: sterilize the asparagus seeds in ozone, and culture them in clean water, with the clean water covering 1 / 4 of the asparagus seeds, and the culture temperature is 27°C.

4. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The calculation formulas for the germination rate and relative salt damage rate of asparagus seeds in step S1 are as follows: Germination rate = (total number of seeds germinated in 12 days / number of seeds tested) × 100% (1); 5. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The process of salt stress treatment of asparagus seedlings in step S2 is as follows: dilute the soil extract to a salt content of 12 g / L, and then mix it with an equal volume of Yamazaki nutrient solution as a culture medium for salt stress treatment, the culture temperature is 28°C from 8:00 to 18:00, and 19°C from 18:00 to 8:00 the next day, the light intensity is 40,000 Lux, and the culture medium is ventilated for 4 hours using a ventilation pump from 8:00 to 10:00 and 15:00 to 17:00 every day.

6. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The calculation formula of the salt damage index in step S2 is as follows: Among them, N is the total number of seedlings, N0 is the number of seedlings with normal growth; N1 is the number of seedlings with normal growth symptoms, but yellowing and chlorosis symptoms on the top of the new stems; N2 is the number of seedlings with inhibited growth of all new stems, yellowing leaves, and a stem rate of less than 20%; N3 is the number of seedlings with symptoms of inhibited growth, yellowing of all above-ground leaves, and a stem rate of 20-60%; N4 is the number of seedlings with symptoms of death and a stem rate of more than 60%.

7. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The asparagus growth indicators measured in step S3 include plant height, stem diameter, stem number, bulb disk diameter, underground fresh weight, underground dry weight, root number, aboveground fresh weight and aboveground dry weight.

8. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The calculation formula of the salt tolerance coefficient in step S3 is as follows: Wherein, SCtg is the salt tolerance coefficient of trait t of genotype g, and Xtgst and Xtgck are the trait values ​​of trait t of genotype f in the salt treatment group and the control group, respectively.

9. The method for identifying salt tolerance of asparagus in the whole growth period for coastal saline-alkali land according to claim 1, characterized in that: The calculation formula of the membership function value of salt tolerance in step S3 is as follows: Among them, Utg is the membership function value of the salt tolerance of trait t of genotype g, SCtmin and SCtmax are the minimum and maximum values ​​of the salt tolerance coefficient of trait t, respectively.

10. The method for identifying salt tolerance of asparagus in the whole growth period for use in coastal saline-alkali land according to claim 1, characterized in that: The formulas for calculating the modified membership function value of salt tolerance and the average value of the modified membership function value of salt tolerance in step S3 are as follows: Among them, Ug is the average value of the membership function of all measured traits of the salt-tolerant genotype g, Ptg is the contribution rate of the trait t of each asparagus variety obtained by principal component analysis, and W is the average value of the modified membership function value of salt tolerance.

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