Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance

Abstract

The invention belongs to the technical field of ornamental plant evaluation, and particularly discloses a lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance, which comprises the following steps: S1, hybridization: performing hybridization by taking a lagerstroemia indica variety of Yakuishan and a low lagerstroemia indica variety as parents; s2, sowing, seedling raising and transplanting; s3, determining the soil property of the saline-alkali soil; s4, determining the ornamental value of the lagerstroemia indica cultivated in the saline S5, observing the cultivation performance of the crape myrtle; s6, constructing a comprehensive evaluation system for ornamental characters and cultivation performance of the lagerstroemia indica in the saline-alkali soil area; and S7, evaluating salt-tolerant related phenotypes and physiological indexes of the I-grade lagerstroemia indica strain with ornamental value and cultivation performance. According to the lagerstroemia indica salt-tolerant germplasm screening method based on the ornamental value and the cultivation performance, comprehensive character scoring is conducted on different offspring of a lagerstroemia indica resistant group according to the hierarchical structure evaluation standard, the ornamental value, the salt-tolerant capacity and the cultivation performance of offspring individuals are identified, and salt-tolerant strains are obtained through screening.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ornamental plant evaluation, and particularly relates to a Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance. BACKGROUND

[0002] Lagerstroemia indica has bright and unique flower type, long flowering period (from June to September), and various plant types (including arbor type, shrub type, dwarf type and vertical type). Therefore, Lagerstroemia indica is one of the most important summer and autumn ornamental woody plants in northern regions and has important ecological and beautifying values in saline-alkali land landscape construction. However, there is little research on the comprehensive evaluation of ornamental value and cultivation performance of resistant Lagerstroemia indica population during saline-alkali land cultivation.

[0003] In the prior art, the screening of Lagerstroemia indica salt-tolerant germplasm is mainly limited to the laboratory, and there are problems such as non-detailed and non-systematic evaluation standards. Meanwhile, the focus of different evaluation methods is scattered, and there are many aspects that need to be improved in practical application, which restricts the screening and related breeding of new salt-tolerant Lagerstroemia indica germplasm. SUMMARY

[0004] The present application aims to provide a Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance, to score the comprehensive traits of different offspring of Lagerstroemia indica resistant population according to hierarchical structure evaluation standards, to identify the ornamental value, salt tolerance and cultivation performance of offspring individuals, and to screen salt-tolerant strains, thereby laying a material foundation for subsequent breeding of new salt-tolerant Lagerstroemia indica germplasm.

[0005] To achieve the above-mentioned purpose, the present application provides a Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance, comprising the following steps:

[0006] S1, hybridization: hybridizing a high, disease-resistant and salt-tolerant wild Lagerstroemia indica species and a low Lagerstroemia indica variety as parents to construct an F1 hybrid population;

[0007] S2, sowing, seedling raising and transplanting: collecting seeds and sowing in a greenhouse, germinating, growing in the greenhouse, and transplanting after the main stem is lignified;

[0008] S3, determination of saline-alkali land soil properties: arranging sampling points in a saline-alkali land test field, taking soil at a depth of 30-50 cm at each point, and measuring soil pH value, relative conductivity and total soil salt content;

[0009] S4, determination of important ornamental traits of Lagerstroemia indica cultivated in saline-alkali land, including flower diameter, inflorescence length, inflorescence width, number of flowers, flower color, plant height, crown width, branching condition, leaf area, tender leaf color and autumn color leaf;

[0010] S5, observe the performance of Lagerstroemia indica cultivation, including disease and insect pests, leaf salt damage, cold resistance, etc.

[0011] S6, construct a comprehensive evaluation model of important ornamental traits and cultivation performance of Lagerstroemia indica in saline-alkali regions, a judgment matrix and calculate the index weight, develop Lagerstroemia indica population index scoring standards in saline-alkali regions, get the comprehensive evaluation results, sort and grade the ornamental value and cultivation performance of Lagerstroemia indica population in saline-alkali regions, and the best is I level.

[0012] S7, carry out evaluation of salt-tolerant related phenotypes and physiological indexes of Lagerstroemia indica with I level of ornamental value and cultivation performance.

[0013] Preferably, in S1, the wild species of Lagerstroemia indica with high height, disease resistance and strong salt tolerance is specifically Yakushima Lagerstroemia indica, and the low Lagerstroemia indica variety is specifically 'Pocomoke'.

[0014] Preferably, the specific steps of S2 are as follows:

[0015] S2.1, remove the wing of the seed at sowing, soak in water for 10-24 hours;

[0016] S2.2, then treat with 200mg / L gibberellin for 10-24 hours;

[0017] S2.3, scatter in the plug tray, no more than 6 seeds per hole, cover with plastic wrap after sowing, keep the temperature at 25-30℃, and thin the seedlings after germination if the seedlings are too dense;

[0018] S2.4, transplant when 6-8 true leaves grow;

[0019] S2.5, greenhouse management: control water and fertilizer, prevent aphids and powdery mildew, and grow in the greenhouse until the main stem is lignified;

[0020] S2.6, transplant to saline-alkali land.

[0021] Preferably, the specific steps of S3 are as follows:

[0022] S3.1, remove all plant residues, gravel and other sundries from the obtained soil sample on site to obtain a sample;

[0023] S3.2, dry the sample naturally by ventilation and in an oven;

[0024] S3.3, crush and grind the sample, and sieve;

[0025] S3.4, measure the soil pH value by potential method, determine the relative conductivity by soil leaching solution conductivity method, and determine the total salt content of the soil by mass method.

[0026] Preferably, the specific steps of S4 are as follows:

[0027] S4.1, randomly select fully open flowers, measure flower diameter, inflorescence length, inflorescence width;

[0028] S4.2, count the number of flowers during the flowering period: use color cards for standard comparison, record petal and leaf color;

[0029] S4.3, measure plant height, crown width, branch length;

[0030] S4.4, randomly select leaves, measure leaf length, width, and calculate leaf area.

[0031] Preferably, S5 has the following specific steps:

[0032] S5.1, observe whether the leaves have notches, powdery mildew, and soot disease, and judge the insect and disease conditions;

[0033] S5.2, observe the salt damage of the leaves, calculate the yellowing rate, and classify the salt damage according to the following criteria: 1st grade yellowing rate < 10%, 10%≤2nd grade yellowing rate < 20%, 20%≤3rd grade yellowing rate < 35%, 35%≤4th grade yellowing rate≤50%, 5th grade yellowing rate > 50%, then measure the dead part of the top of the branch, and comprehensively evaluate the damage degree of Lagerstroemia indica under salt stress;

[0034] S5.3, observe the survival of spring branches of the plant, and judge its cold resistance.

[0035] Preferably, S6 has the following specific steps:

[0036] S6.1, establish a hierarchical structure evaluation model combining the breeding objectives of Lagerstroemia indica and its biological and ornamental characteristics, which is divided into four layers: target layer A, constraint layer C n , standard layer P n and lowest layer D n , the target layer A reflects the comprehensive ornamental value of Lagerstroemia indica in saline-alkali soil, the constraint layer C n includes flower traits C1, plant type characteristics C2, leaf traits C3 and cultivation adaptability C4, the standard layer P n is a sub-item of the constraint layer C n , and the lowest layer D n is the F1 generation individual of Lagerstroemia indica to be evaluated;

[0037] S6.2, construct a judgment matrix and calculate the index weight: compare the factors of the constraint layer C n and the standard layer P n two by two, use the 1-9 ratio scale method to assign values to the relative importance, and then average the values to construct A-C n , C n -P nThe judgment matrix is subjected to consistency checking, and the judgment matrix passing the consistency checking is subjected to weighted calculation to obtain the total weight of each factor relative to the total target layer;

[0038] S6.3, making a score standard of each index of Lagerstroemia indica population in saline-alkali soil: according to ornamental characteristics and breeding goals of Lagerstroemia indica, combined with expert opinions, a score standard is made, and the total score is calculated by combining the ornamental evaluation indexes and the weight of cultivation performance, and the score is sequenced according to the size, and finally the high and low of the comprehensive ornamental value is determined;

[0039] S6.4, obtaining a comprehensive evaluation result: according to the score standard of each index of Lagerstroemia indica in saline-alkali soil, the ornamental characteristics and cultivation performance of Lagerstroemia indica are scored respectively, the weight of each evaluation index is used for weighted calculation to obtain the comprehensive evaluation score of the ornamental characteristics and cultivation performance of Lagerstroemia indica in saline-alkali soil, and the above comprehensive evaluation score of the ornamental value and cultivation performance of Lagerstroemia indica in saline-alkali soil is sequenced and graded according to expert opinions and cultivation and maintenance experience, and the optimal is grade I.

[0040] Preferably, in S6.2, Yaahp6.0 software is applied for consistency checking, and when the consistency ratio CR is less than 0.1, it is considered that the matrix has satisfactory consistency and passes the consistency checking.

[0041] Preferably, the specific steps of S7 are as follows:

[0042] S7.1, taking semi-lignified current-year branches of Lagerstroemia indica strain with the comprehensive evaluation result of ornamental value and cultivation performance being grade I to make cuttings for cutting propagation, taking the mixture of perlite and vermiculite as the substrate, and cutting the cutting hole at a temperature of 31±2 DEG C and an air humidity of 80%±5%, and rooting;

[0043] S7.2, adopting a bare root soaking method to perform salt treatment on the rooted seedlings, observing the wilting degree of leaves of the grade I Lagerstroemia indica after 0.5-2 days, and measuring related physiological indexes.

[0044] The salt-tolerant related physiological indexes include chlorophyll content in leaves, soluble sugar content, soluble protein content, malondialdehyde content, lignin content and antioxidant enzyme activity in leaves and root systems.

[0045] Therefore, the Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance has the following beneficial effects:

[0046] (1) The traditional method only focuses on a single trait, such as only evaluating the flowering amount, and ignoring the interaction between traits. The Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance decomposes complex ornamental characteristics and cultivation performance into a hierarchical index system (target layer, constraint layer, standard layer and lowest layer), and avoids the problem of scattered indexes in the traditional method.

[0047] (2) Fixed weight method is difficult to adapt to regional differences. The application can flexibly adjust the weight of the constraint layer and the standard layer according to different saline-alkali environment, such as increasing the salt tolerance weight in high salt area, to realize personalized evaluation.

[0048] (3) Simple scoring method cannot solve the conflict between traits. The ornamental value and adaptability of Lagerstroemia indica in saline-alkali soil should be considered in this method, and the rationality of weight distribution can be verified through consistency test (CR<0.1) to balance the contradictory goals.

[0049] (4) The application plants the resistant Lagerstroemia indica population in saline-alkali soil, and conducts comprehensive evaluation of the ornamental value and cultivation performance of Lagerstroemia indica strains in the field, and further screens salt-tolerant Lagerstroemia indica germplasm in combination with laboratory salt treatment, so that the accuracy of the screening result is improved.

[0050] The technical solutions of the application will be further described in detail below with the help of the drawings and examples. DESCRIPTION OF DRAWINGS

[0051] Figure 1 is a flow chart of Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance according to an embodiment of the application;

[0052] Figure 2 is an I-grade Lagerstroemia indica effect diagram according to the second embodiment of the Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance of the application;

[0053] Figure 3 is the chlorophyll content of I-grade Lagerstroemia indica strains before and after salt treatment according to the second embodiment of the Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance of the application;

[0054] Figure 4 is the relative conductivity and malondialdehyde content of I-grade Lagerstroemia indica strains before and after salt treatment according to the second embodiment of the Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance of the application, wherein a is the relative conductivity and b is the malondialdehyde;

[0055] Figure 5 is the soluble sugar and soluble protein content of I-grade Lagerstroemia indica strains before and after salt treatment according to the second embodiment of the Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance of the application, wherein a is the soluble sugar and b is the soluble protein;

[0056] Figure 6 is the antioxidant enzyme activity of I-grade Lagerstroemia indica strains before and after salt treatment according to the second embodiment of the Lagerstroemia indica salt-tolerant germplasm screening method based on ornamental value and cultivation performance of the application, wherein a is the superoxide dismutase SOD content and b is the peroxidase POD content. DETAILED DESCRIPTION

[0057] The technical solutions of the present application are further described below by means of the drawings and examples.

[0058] Unless otherwise defined, technical or scientific terms used in the present application shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0059] Example 1

[0060] As Figure 1 shown, a salt-tolerant germplasm screening method of Lagerstroemia indica based on ornamental value and cultivation performance comprises the following steps:

[0061] Step 1, hybridization: taking Yakushima Lagerstroemia indica with high height, disease resistance and strong salt tolerance and a low Lagerstroemia indica variety ‘Pocomoke’ as parents, a F1 population is constructed by hybridization.

[0062] Step 2, sowing, seedling raising and transplanting: the seeds are collected and sowed in a greenhouse, and germination can be achieved after about 2 weeks, and the seedlings are grown in the greenhouse for 4-5 months, and then transplanted after the main stem is lignified.

[0063] The specific steps of sowing, seedling raising and transplanting are as follows:

[0064] Step 2.1, the wing of the seed is removed when sowing, and first soaked in tap water for 12 hours;

[0065] Step 2.2, then treated with 200 mg / L gibberellin for 12 hours;

[0066] Step 2.3, sowed in a plug tray, no more than 6 seeds per hole, covered with plastic wrap after sowing, and placed in an artificial climate chamber, keeping the temperature at 25-30℃, and germination can be achieved after 2 weeks, and thinning is needed for the seedlings with high density;

[0067] Step 2.4, potted when 6-8 true leaves grow, initially using 8 cm nutrient pots, and then changing to larger nutrient pots when the seedlings grow well;

[0068] Step 2.5, the greenhouse management needs to control water and fertilizer, and prevent the breeding of aphids and powdery mildew, and the seedlings are grown in the greenhouse for 4 months, and then transplanted to the field after the main stem is lignified;

[0069] Step 2.6, transplanted to saline-alkali soil, which is a mixed type of saline-alkali soil in a certain plain (both sides of the river).

[0070] Step 3, determination of soil properties of saline-alkali soil: four sampling points are arranged in the saline-alkali soil test field, and soil is taken from each point at a depth of 30 cm. The soil pH value, relative conductivity and total salt content are measured.

[0071] The specific steps of determination of soil properties of saline-alkali soil are as follows:

[0072] Step 3.1, remove all plant residues, gravel and other debris from the soil sample on site, transport to the laboratory;

[0073] Step 3.2, dry by natural ventilation and oven drying;

[0074] Step 3.3, place the sample in a mortar for crushing and grinding, then sieve through a 2mm diameter screen to prepare a sample suitable for subsequent testing;

[0075] Step 3.4, measure the pH of the soil by potentiometry, determine the relative conductivity of the soil leachate by conductivity method, and determine the total salt content of the soil by mass method.

[0076] Step 4, determine the important ornamental traits of Lagerstroemia indica: flower diameter, inflorescence length, inflorescence width, number of flowers, flower color, plant height, crown width, branching, leaf area, tender leaf color, autumn color leaf.

[0077] The specific steps for determining the important ornamental traits of Lagerstroemia indica are as follows:

[0078] Step 4.1, randomly select 3 fully open flowers, measure the flower diameter with a vernier caliper, and measure the inflorescence length and width with a tape measure;

[0079] Step 4.2, count the number of flowers during the flowering period: use the Royal Horticultural Society (RHS) color chart (RHS Colour Chart) for standard comparison, and record the petal and leaf color;

[0080] Step 4.3, measure the plant height, crown width, and branch length with a tape measure;

[0081] Step 4.4, randomly select 3 leaves, measure the length and width of the leaves with a vernier caliper, and calculate the leaf area.

[0082] Step 5, observe the cultivation performance of Lagerstroemia indica: disease and insect pests, leaf salt damage, and cold resistance.

[0083] The specific steps for observing the important cultivation performance of Lagerstroemia indica are as follows:

[0084] Step 5.1, observe whether the leaves have notches, powdery mildew, and soot disease, and judge the insect and disease conditions;

[0085] Step 5.2, observe the leaf salt damage, calculate the yellowing rate, and classify the salt damage as follows: 1st grade yellowing rate < 10%, 10% ≤ 2nd grade yellowing rate < 20%, 20% ≤ 3rd grade yellowing rate < 35%, 35% ≤ 4th grade yellowing rate ≤ 50%, and 5th grade yellowing rate > 50%, then measure the dead part at the top of the branch, and comprehensively evaluate the damage degree of Lagerstroemia indica under salt damage;

[0086] Yellowing rate = (number of yellowing leaves / total number of leaves) × 100%;

[0087] Step 5.3, judge the cold resistance ability of the plant by observing the survival of spring branches.

[0088] Step 6, construct a comprehensive evaluation system for ornamental traits and cultivation performance of Lagerstroemia indica in saline-alkali regions: construct a comprehensive evaluation model, judgment matrix and calculate the index weight of important ornamental traits and cultivation performance of Lagerstroemia indica in saline-alkali regions, develop the scoring criteria for each index of Lagerstroemia indica population in saline-alkali regions, obtain the comprehensive evaluation results, sort the comprehensive evaluation scores of ornamental value and cultivation performance of Lagerstroemia indica population in saline-alkali regions, and divide them into four levels, with the best being level I.

[0089] The specific steps of constructing the comprehensive evaluation system for ornamental traits and cultivation performance of Lagerstroemia indica in saline-alkali regions are as follows:

[0090] Step 6.1, establish a hierarchical evaluation model based on the breeding goals of Lagerstroemia indica and its biological characteristics and ornamental characteristics, as shown in Table 1. The evaluation model is divided into four layers: target layer (A), constraint layer (C n ), standard layer (P n ) and lowest layer (D n ). The target layer (A) of the comprehensive evaluation system for ornamental traits and cultivation performance of Lagerstroemia indica in saline-alkali regions reflects the comprehensive ornamental value of Lagerstroemia indica in saline-alkali regions. The constraint layer (C n ) is composed of four aspects that affect the ornamental value of Lagerstroemia indica in saline-alkali regions, including flower traits (C1), plant type characteristics (C2), leaf traits (C3) and cultivation adaptability (C4). The standard layer (P n ) is the sub-item of the constraint layer, which is composed of 14 evaluation indexes of ornamental value and cultivation performance. The lowest layer (D n ) is the F1 generation of Lagerstroemia indica to be evaluated;

[0091] Table 1 Comprehensive evaluation system for ornamental characteristics and cultivation performance of Lagerstroemia indica in saline-alkali regions

[0092]

[0093]

[0094] Step 6.2, construct the judgment matrix and calculate the index weight: compare the factors of the constraint layer and the standard layer pairwise, assign values to the relative importance degree using the 1-9 ratio scale method, average the values after summarizing, and thus construct five judgment matrices A-C 1-4 , C1-P 1-5 , C2-P 6-8 , C3-P 9-11 , C4-P 12-14 . The judgment matrix that passes the consistency test is used to calculate the weight using Excel software, and the total weight of each factor relative to the total target layer is obtained;

[0095] Consistency test was performed by using Yaahp 6.0 software. When the consistency ratio CR was less than 0.1, it was considered that the matrix had satisfactory consistency and passed the consistency test.

[0096] Step 6.3, establishing the score standard of each index of K. wigginites population in saline-alkali soil: according to the ornamental characteristics and breeding objectives of K. wigginites, combined with expert opinions, a 5-point scoring standard was established. The total score was calculated by combining the ornamental evaluation indexes and the weight of cultivation performance. The final determination of the high and low of the comprehensive ornamental value was based on the size of the score.

[0097] Step 6.4, obtaining the comprehensive evaluation result: according to the score standard of each index of K. wigginites in saline-alkali soil, the 14 ornamental traits and cultivation performance of K. wigginites were scored respectively. The comprehensive evaluation score of ornamental traits and cultivation performance of K. wigginites in saline-alkali soil was obtained by weighted calculation using the weight of each evaluation index. Combined with expert opinions and cultivation and maintenance experience or using the knowledge graph module, the above comprehensive evaluation score of ornamental value and cultivation performance of K. wigginites in saline-alkali soil was sorted and divided into four levels.

[0098] Step 7, carrying out the evaluation of salt tolerance related phenotypes and physiological indexes of I-level K. wigginites strain with ornamental value and cultivation performance.

[0099] The specific steps of carrying out the evaluation of salt tolerance related phenotypes and physiological indexes of I-level K. wigginites strain with ornamental value and cultivation performance are as follows:

[0100] Step 7.1, taking the semi-lignified current-year branches of K. wigginites strain with I-level comprehensive evaluation result of ornamental value and cultivation performance to make cuttings. The cuttings were quickly dipped in 50ppm double-gil-GGR6 rooting powder for 15 seconds. The cuttings were propagated by cutting, and the substrate was configured by mixing perlite and vermiculite (volume ratio 1:1). The cutting hole tray was placed in a temperature of 31±2℃ and an air humidity of 80%±5%. The rooting could be achieved in 14-20 days, and the rooting rate could reach about 95%.

[0101] Step 7.2, the rooted seedlings were treated with salt by using the bare root soaking method. Before treatment, the seedlings were treated with 1 / 2 Hoagland solution for 5 days, and then treated with 100mM NaCl solution. After 2 days, the wilting degree of I-level K. wigginites leaves was observed, and the salt tolerance related physiological indexes were measured.

[0102] The salt tolerance related physiological indexes included: leaf chlorophyll content, soluble sugar content, soluble protein content, malondialdehyde (MDA) content, lignin content and antioxidant enzyme activity of leaves and roots.

[0103] Example Two

[0104] The screening method of example one was used, and the soil samples were collected from the K. wigginites planting area in a certain industrial demonstration area.

[0105] The region is a typical coastal alluvial plain, with gentle terrain. The climate type belongs to the warm temperate monsoon climate zone, with abundant light and heat resources. The average annual temperature is 13.1±0.5℃, and the frost sensitive period is 205±8 days. The seasonal difference of precipitation is significant, with an average annual precipitation of 556.0±72.8mm. The concentrated precipitation in the flood season (June-August) accounts for 65.3% of the annual total, which is typical and representative of the regional ecosystem. The results of soil index determination show that the soil pH value is 8.55, the electrical conductivity is 496.5 μs / cm, and the total salt content is 3.3 g / kg, i.e. 0.3%, which belongs to the level of moderate saline-alkali soil.

[0106] Based on the ornamental characteristics of Lagerstroemia indica and relevant literature, a 5-point scoring standard for Lagerstroemia indica population in saline-alkali soil was developed, as shown in Table 1. On this basis, the ornamental value and cultivation performance of the plant were combined to calculate the total score, and the scores were arranged from high to low to determine the size of the comprehensive ornamental value.

[0107] Table 2 Scoring standard for each index of Lagerstroemia indica population in saline-alkali soil

[0108]

[0109]

[0110] The judgment matrix and consistency test of Lagerstroemia indica in saline-alkali soil and the weight of each ornamental evaluation index are shown in Table 3.

[0111] Table 3 Judgment matrix and consistency test of Lagerstroemia indica in saline-alkali soil and weight of ornamental evaluation index

[0112]

[0113]

[0114] According to the scoring standard of each index of Lagerstroemia indica in saline-alkali soil, the 14 ornamental value indexes of 59 Lagerstroemia indica plants were scored and weighted to obtain the comprehensive evaluation score of the ornamental value of 59 Lagerstroemia indica plants in saline-alkali soil. Combined with expert opinions and cultivation experience, the above comprehensive evaluation score of the ornamental value of Lagerstroemia indica in saline-alkali soil was sorted and divided into 4 levels, as shown in Table 4. Level I (4.0 or above), high ornamental value, including DY2-4, DY5-2, DY5-4, DY1-9, DY3-17, DY3-3, DY5-17, DY2-16, DY5-19, a total of 9 species, such as Figure 2The 20 species of grade I (3.5-4.0) have high ornamental value, including DY3-15, DY3-12, DY1-19, DY2-10, DY1-2, DY1-7, DY1-24, DY3-19, DY1-8, DY1-21, DY2-20, DY2-1, DY4-3, DY3-11, DY2-7, DY2-9, DY4-14, DY6-20, DY3-2, and DY1-4; the 17 species of grade III (3.0-3.5) have medium ornamental value, including DY4-4, DY3-9, DY1-12, DY3-5, DY4-11, DY3-8, DY3-22, DY1-6, DY2-3, DY6-3, DY5-7, DY1-14, DY9-5, DY7-13, DY2-21, DY4-9, and DY7-7; and the 13 species of grade IV (3.0 or less) have low ornamental value, including DY6-7, DY4-17, DY4-8, DY6-19, DY2-19, DY1-20, DY6-8, DY1-15, DY2-11, DY3-7, DY6-11, DY5-18, and DY9-6.

[0115] Table 4 Comprehensive evaluation score results of 459 strains of K. indica in saline-alkali soil

[0116]

[0117]

[0118] Test test

[0119] Comprehensive evaluation of salt tolerance of grade I K. indica strains obtained in Example 2

[0120] 1. Effect of salt stress on plant growth

[0121] After salt stress treatment, the leaves of the 9 K. indica strains all showed wilting symptoms to varying degrees, but the damage degree of different varieties was different, and the wilting degree is shown in Table 5.

[0122] Table 5 Wilting degree of grade I K. indica strains under different salt stress

[0123]

[0124] Note: Grade 0 means that the leaves of K. indica have no wilting and the growth is good; grade 1 means that less than 1 / 5 of the leaves of K. indica appear wilting; grade 2 means that 1 / 3-1 / 2 of the leaves of K. indica appear wilting; grade 3 means that 1 / 2-2 / 3 of the leaves of K. indica appear wilting; grade 4 means that more than 2 / 3 of the leaves of K. indica appear wilting; and grade 5 means that all the leaves of K. indica appear wilting.

[0125] 2. Effect of salt stress on leaf chlorophyll content

[0126] Salt stress affects photosynthesis of plants, and chlorophyll is the basis of photosynthesis. As shown in Figure 2, under 100 mmol / L salt treatment, the chlorophyll content of DY2-4 decreased the least, and it could maintain a high chlorophyll content under salt stress, which was conducive to photosynthesis, thereby having strong salt tolerance; DY5-2, DY5-4, DY1-9, and DY2-16 were the second; DY3-3, DY3-17, DY5-17, and DY5-19 showed strong sensitivity to salt stress, and the synthesis of photosynthetic pigments was greatly affected, and their salt tolerance was relatively weak. Figure 3

[0127] 3. Effects of salt stress on leaf relative conductivity and malondialdehyde content

[0128] The leaf relative conductivity of the nine I-level Lagerstroemia indica strains was relatively low under the control (CK) treatment, and there was no significant difference. When the salt stress treatment concentration was 100 mmol / L, as shown in a of Figure 3, the leaf relative conductivity of the nine Lagerstroemia indica strains showed an upward trend, and the relative conductivity of DY2-4 and DY5-4 increased slowly, and the leaf relative conductivity of DY3-17 and DY5-19 had a very significant difference from CK. This phenomenon indicated that the cell membrane of DY2-4 and DY5-4 was less damaged by salt stress, and they showed good salt tolerance. In addition, as shown in b of Figure 3, the malondialdehyde mass molar concentration in the leaves of the nine Lagerstroemia indica strains also showed an upward trend under salt stress, and the change trend was basically the same as that of the relative conductivity. Figure 4 Figure 4 4. Effects of salt stress on leaf soluble sugar and soluble protein content

[0129] Before salt treatment, the soluble sugar content of the nine Lagerstroemia indica strains was less than 100 mmol / L salt stress treatment, indicating that the nine Lagerstroemia indica strains could cope with salt stress by promoting the synthesis and accumulation of soluble sugar to improve the osmotic pressure of cells and maintain life metabolic activities. As shown in a of Figure 4, DY2-4 and DY2-16 showed the most significant upward trend. In addition, under salt stress, the leaf soluble protein content showed a downward trend compared with CK, indicating that Lagerstroemia indica could decompose the protein stored in its body to provide necessary nitrogen source for life metabolic activities to adapt to salt stress. As shown in b of Figure 4, DY3-17, DY5-17, and DY5-19 showed the most significant downward trend.

[0130] 5. Effects of salt stress on leaf antioxidant enzyme activity Figure 5 Figure 5

[0131] 5. Effects of salt stress on leaf antioxidant enzyme activity

[0132] ​​​​Under 100 mmol / L salt stress, the activities of superoxide dismutase (SOD) and peroxidase (POD) showed significant differences among different strains. Superoxide dismutase activity showed a decreasing trend in all nine Lagerstroemia indica strains, such as... Figure 6 As shown in a, DY2-4 and DY5-4 showed the least significant changes; followed by DY5-2, DY5-4, DY1-9, and DY2-16; and DY3-17, DY5-17, and DY5-19 showed the most significant changes. Peroxidase activity showed an increasing trend in all nine Lagerstroemia indica lines, such as... Figure 6 As shown in b, the changes in DY3-17, DY5-17, and DY5-19 were the least significant; followed by DY5-2, DY5-4, DY1-9, and DY2-16; while DY2-4 and DY5-4 showed significant changes. The data indicate that the changes in antioxidant enzyme activity in the leaves of the nine Lagerstroemia indica lines under salt stress lack a clear pattern, making it impossible to determine the strength of salt tolerance based on the activity of a single antioxidant enzyme.

[0133] In summary, the salt tolerance of nine first-order progeny lines in the F1 generation of Lagerstroemia indica was comprehensively evaluated using the membership function method. The evaluation results are shown in Table 6. The salt tolerance of the nine Lagerstroemia indica lines, from highest to lowest, is as follows: DY2-4, DY5-4, DY5-2, DY2-16, DY1-9, DY3-3, DY5-17, DY3-17, and DY5-19. This ranking is basically consistent with the leaf stress injury symptoms of each variety.

[0134] Table 6. Comprehensive Evaluation of Salt Tolerance of Grade I Crape Myrtle Offspring

[0135]

[0136]

[0137] Therefore, this invention adopts the above-mentioned method for screening salt-tolerant crape myrtle germplasm based on ornamental value and cultivation performance. According to the hierarchical structure evaluation criteria, the different offspring of the resistant crape myrtle population are comprehensively trait-scored to identify the ornamental value, salt tolerance and cultivation performance of individual offspring, and salt-tolerant lines are screened to lay the material foundation for the subsequent cultivation of new salt-tolerant crape myrtle germplasm.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance, characterized in that, Comprise the following steps: S1, hybridization: high, disease-resistant and salt-tolerant wild species of Lagerstroemia indica and low Lagerstroemia indica varieties as parents to cross, to construct F1 hybrid population; S2, sowing, seedling and transplanting: seed collection and sowing in greenhouse, germination, growth in greenhouse, after the main stem lignification, transplanting; S3, saline soil property determination: saline land test field layout sampling point, each point according to 30-50 cm depth of soil, measurement of soil pH, relative conductivity, soil total salt content; S4, determination of saline land Lagerstroemia indica important ornamental traits, including flower diameter, inflorescence length, inflorescence width, flower number, flower color, plant height, crown width, branching, leaf area, tender leaf color, autumn color leaf; S5, observation of Lagerstroemia indica cultivation performance, including disease and insect pests, leaf salt injury, cold resistance; S6, construction of saline area Lagerstroemia indica important ornamental traits and cultivation performance comprehensive evaluation model, judgment matrix and calculation index weight, to develop saline area Lagerstroemia indica population each index scoring standard, get comprehensive evaluation result, the ornamental value and cultivation performance of saline area Lagerstroemia indica population comprehensive evaluation score is sorted and divided into grades, the best is I level; S7, to carry out the ornamental value and cultivation performance I Lagerstroemia indica strain salt related phenotype and physiological index evaluation.

2. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 1, characterized in that, In S1, high, disease-resistant and salt-tolerant wild species of Lagerstroemia indica is Yagujidao Lagerstroemia indica, low Lagerstroemia indica varieties is 'Pocomoke'.

3. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 1, characterized in that, The specific steps of S2 are as follows: S2.1, remove the wing of seed at sowing, soak in water for 10-24 hours; S2.2, then treated with 200 mg / L gibberellin for 10-24 hours; S2.3, scatter in hole tray, no more than 6 seeds per hole, cover with plastic wrap after sowing, keep the temperature between 25-30℃, after germination, for the dense seedling should be thinned; S2.4, when 6-8 true leaves grow, pot; S2.5, greenhouse management: control water and fertilizer, prevent aphids and powdery mildew, grow in greenhouse until the main stem lignification; S2.6, transplanting to saline land.

4. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 1, characterized in that, The specific steps of S3 are as follows: S3.1, the obtained soil sample is removed from all plant residues, gravel and other sundries in situ, and the sample is obtained; S3.2, the sample is naturally ventilated and dried and treated by oven drying; S3.3, the sample is crushed and ground, and sieved; S3.4, the soil pH value is measured by potential method, the relative conductivity is measured by soil leaching liquid conductivity method, and the soil total salt content is measured by mass method.

5. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 1, characterized in that, The specific steps of S4 are as follows: S4.1, randomly select fully open flowers, measure flower diameter, inflorescence length and inflorescence width; S4.2, count the number of flowers in the flowering period: use colorimetric card for standard comparison, record the color of petals and leaves; S4.3, measure plant height, crown width and branch length; S4.4, randomly select leaves, measure leaf length and width, and calculate leaf area.

6. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 1, characterized in that, The specific steps of S5 are as follows: S5.1, observe whether there are notches, powdery mildew and soot disease on the leaves, and judge the insect and disease conditions; S5.2, observe the salt damage of leaves, calculate the yellowing rate, and classify the salt damage: 1st grade yellowing rate <10%, 10%≤2nd grade yellowing rate <20%, 20%≤3rd grade yellowing rate <35%, 35%≤4th grade yellowing rate≤50%, 5th grade yellowing rate >50%, then measure the dead part of the top of the branch, and comprehensively evaluate the damage degree of Lagerstroemia indica under salt stress; S5.3, observe the survival of branches in spring, and judge the cold resistance of Lagerstroemia indica.

7. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 1, characterized in that, S6.3, the scoring criteria of Lagerstroemia indica population in saline-alkali soil are formulated: according to the ornamental characteristics and breeding objectives of Lagerstroemia indica, combined with the opinions of experts, the scoring criteria are formulated, the total score is calculated by combining the ornamental evaluation index and the weight of cultivation performance, the order is determined according to the score, and the high and low of the comprehensive ornamental value is finally determined; S6.1, combined with Lagerstroemia indica breeding target and its biological characteristics and ornamental characteristics, a hierarchical evaluation model is established, which is divided into four layers: target layer A, constraint layer C n , standard layer P n and the lowest layer D n , the target layer A reflects the comprehensive ornamental value of Lagerstroemia indica in saline-alkali soil, the constraint layer C n includes flower traits C1, plant type characteristics C2, leaf traits C3 and cultivation adaptability C4, the standard layer P n is the sub-item of the constraint layer C n , and the lowest layer D n is the F1 generation individual of Lagerstroemia indica to be evaluated; S6.2, construct judgment matrix and calculate index weight: compare the factors of constraint layer C n and standard layer P n with each other, assign values to the relative importance degree by using 1-9 ratio scale method, average after collection, thereby constructing A-C n , C n -P n judgment matrix, and through the judgment matrix of consistency test, weighted calculation is carried out to obtain the total weight of each factor relative to the total target layer; S6.4, the comprehensive evaluation result is obtained: according to the scoring criteria of each index of Lagerstroemia indica in saline-alkali soil, the ornamental characteristics and cultivation performance of Lagerstroemia indica are scored respectively, the weight of each evaluation index is used for weighted calculation, the comprehensive evaluation score of ornamental characteristics and cultivation performance of Lagerstroemia indica in saline-alkali soil is obtained, the above comprehensive evaluation score of ornamental value and cultivation performance of Lagerstroemia indica in saline-alkali soil is sorted and graded, and the optimal is grade I. In S6.2, Yaahp6.0 software is used for consistency test, when the consistency ratio CR<0.1, it is considered that the matrix has satisfactory consistency, and the consistency test is passed.

8. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 7, characterized in that, S7.1, the semi-lignified current-year branches of Lagerstroemia indica strain with grade I comprehensive evaluation result of ornamental value and cultivation performance are used to make cuttings for propagation, the mixture of perlite and vermiculite is used as the substrate, the cutting hole is placed in the temperature of 31±2℃ and the air humidity of 80%±5%, and rooting is carried out; 9. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 1, characterized in that, S7.2, the bare root soaking method is used for salt treatment of the rooted seedlings, after 0.5-2 days, the salt tolerance related phenotype index and the salt tolerance related physiological index of Lagerstroemia indica of grade I are observed. In S7.2, the salt tolerance related phenotype index is represented by the wilting degree of leaves; The salt tolerance related physiological index includes: leaf chlorophyll content, soluble sugar content, soluble protein content, malondialdehyde content, lignin content and antioxidant enzyme activity of leaves and roots.

10. The method for screening salt-tolerant germplasm of Lagerstroemia indica based on ornamental value and cultivation performance according to claim 9, characterized in that, ​ ​

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