Composite plant stress-resistant agent as well as preparation method and application thereof

Abstract

The invention discloses a compound plant stress-resistant agent as well as a preparation method and application thereof. The compound plant stress-resistant agent comprises a compound of glycine betaine and polyglutamic acid, wherein the mass ratio of the glycine betaine to the polyglutamic acid is 1: (0.1-2). The preparation method of the composite plant stress-resistant agent comprises the following steps: mixing polyglutamic acid or a solution thereof with glycine betaine in ethanol to obtain a mixed solution, adjusting the pH value of the mixed solution to 3.0-6.0, carrying out an ultrasonic reaction to obtain a reaction solution, adding absolute ethyl alcohol into the reaction solution, stirring, filtering, and drying the precipitate to obtain the composite plant stress-resistant agent. The compound plant stress-resistant agent can be applied to crops in a foliage spraying or root irrigation mode, the growth conditions of grain crops such as corn, peanuts, celery and grapes and / or economic crops under adversity stress such as drought, low temperature and high salt are remarkably relieved, and the crop yield is increased.

Description

Technical Field

[0001] The invention belongs to the field of plant nutrition, and specifically relates to a composite plant stress-resistant agent and a preparation method and application thereof. Background Art

[0002] Frequent extreme weather and land deterioration caused by excessive use of fertilizers have become challenges that my country often faces in agricultural production. In the past five years, the average annual crop area affected by natural disasters such as drought, flood, wind and hail, high temperature heat damage, and low temperature cold damage in my country has reached 220 million mu, and grain production has decreased by more than 50 billion kilograms; the salinization area of ​​cultivated land caused by excessive use of chemical fertilizers has reached 108 million mu, and there are still 263 million mu of land under the potential threat of salinization, which has become an important reason for the lack of grain production in my country. Therefore, adverse environments and climates such as high salt, drought, and low temperature are abiotic stresses that plants often face during growth. They will affect the water potential inside and outside the cell membrane of crops, reduce the extracellular water potential, cause osmotic stress, and ultimately cause cell dehydration, resulting in weakened crop growth and even death. In addition, these abiotic stresses can also cause excessive accumulation of reactive oxygen species (ROS) in crop cells, causing damage to cell membrane structure, damage to intracellular proteins and DNA, and photosynthesis disorders. Therefore, developing plant stress resistors and improving the ability of crops to cope with adverse climate and farmland degradation are of great research significance and value for ensuring stable grain production increases.

[0003] Glycine betaine (betaine) is a product of industrial synthesis and a small molecule amino acid derivative. Glycine betaine is a plant stress resistance agent that promotes the improvement of plant stress resistance. Glycine betaine has good biodegradability and is a natural plant endogenous substance. It is a safe and non-toxic plant endogenous osmotic pressure regulator, but it has application defects such as easy loss and easy degradation.

[0004] Polyglutamic acid is a microbial fermentation product. It is a homopolyamide composed of α-amino and γ-carboxyl groups bonded by amide bonds. - Group, which can react with NH4 in nitrogen fertilizer + , K in potash fertilizer + , Ca in elemental fertilizers 2+ Mg 2+ Combined to form a stable glutamate aqueous solution, slowly providing nutrition to plants.

[0005] Taking advantage of the structural characteristics of polyglutamic acid, it can be combined with the nitrogen atom of glycine betaine to form a stable complex system, which can slowly and continuously provide glycine betaine to plants.

[0006] In the existing technology, glycine betaine and polyglutamic acid are not compounded as plant stress resistance agents. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a composite plant stress resistance agent containing glycine betaine and polyglutamic acid in view of the deficiencies of the prior art.

[0008] The technical problem that the present invention also solves is to provide a method for preparing the composite plant stress resistance agent containing glycine betaine and polyglutamic acid.

[0009] The technical problem that the present invention also solves is to provide the application of the above-mentioned composite plant stress resistance agent in plants resisting adverse stress and promoting plant growth.

[0010] To achieve the above object, the technical solution of the present invention is as follows:

[0011] A composite plant stress-resistant agent comprises a composite of glycine betaine and polyglutamic acid; wherein the mass ratio of the glycine betaine to the polyglutamic acid is 1:0.1-2.0.

[0012] Wherein, the polyglutamic acid can be replaced by polyglutamate salt, and the polyglutamate salt is any one or a combination of polyglutamate sodium salt, polyglutamate potassium salt, polyglutamate calcium salt, polyglutamate manganese salt, polyglutamate copper salt, polyglutamate zinc salt and polyglutamate iron salt.

[0013] Wherein, the molecular weight of the polyglutamic acid or polyglutamate salt is greater than or equal to 700 kDa, preferably 700-1000 kDa.

[0014] The complex of glycine betaine and polyglutamic acid is a supramolecular complex formed by glycine betaine and polyglutamic acid through electrostatic self-assembly.

[0015] The present invention also discloses a preparation method of the composite plant stress-resistant agent: polyglutamic acid or its solution is mixed with glycine betaine in ethanol to obtain a mixed solution, the pH of the mixed solution is adjusted to 3.0-6.0, ultrasonic reaction is performed to obtain a reaction solution, anhydrous ethanol is added to the reaction solution, stirred, filtered, and the precipitate is dried to obtain the composite plant stress-resistant agent.

[0016] Wherein, the polyglutamic acid or its solution is mixed with glycine betaine in ethanol. When polyglutamic acid is used, the ethanol is a 50% v / v ethanol aqueous solution; when a polyglutamic acid solution is used, the amount of ethanol added is equal to the volume of the polyglutamic acid solution, and the ethanol is anhydrous ethanol.

[0017] The glycine betaine is pure glycine betaine (purity ≥ 98%); the polyglutamic acid solution is polyglutamic acid or its salt; the polyglutamic acid solution is any one or a combination of an aqueous solution of polyglutamic acid or its salt, a fermentation broth containing polyglutamic acid or its salt, and an aqueous solution of a dried product of the fermentation broth of polyglutamic acid or its salt; the concentration of the glycine betaine in the mixed solution is 10-50 g / L, and the concentration of the polyglutamic acid or its salt in the mixed solution is 1-100 g / L.

[0018] The amount of anhydrous ethanol added is equal to the volume of the reaction solution; the drying is performed at a temperature of 50 to 80°C for 6 to 12 hours; the pH of the mixed solution is adjusted to 3.0 to 6.0 using hydrochloric acid or sulfuric acid; the ultrasound has a frequency of 20 to 60 kHz and a time of 10 to 60 minutes.

[0019] The composite plant stress-resistant agent of the present invention can be in the form of paste, water or powder.

[0020] By utilizing the structural characteristics of glycine betaine being an amphoteric small molecule compound and polyglutamic acid being an anionic polymer, the two can form a supramolecular complex through electrostatic self-assembly, which improves the stability of glycine betaine while exerting a synergistic effect of the two. Through the above preparation method, polyglutamic acid can be combined with the nitrogen atom on glycine betaine to form a stable compound system, which can slowly and continuously provide glycine betaine to plants.

[0021] The invention also discloses the application of the composite stress-resistant agent containing glycine betaine and polyglutamic acid in resisting adverse stress of plants and promoting plant growth.

[0022] Wherein, the adverse stress is any one or a combination of salt stress, low temperature stress and drought stress; the salt stress is 100mM NaCl stress; the temperature of the low temperature stress is 8°C; the high temperature stress is the temperature is greater than or equal to 35°C and for more than 3 consecutive days; the plants are food crops and / or economic crops, preferably rice, peanuts, grapes, corn and celery, and most preferably rice, peanuts and grapes.

[0023] The method for using the composite plant stress-resistant agent is as follows: after the composite plant stress-resistant agent is prepared into a solution with a concentration of 50-200 ppm with water, the solution is sprayed on the leaves of crops or irrigated with roots, the application amount is 10-30 L / mu, and the interval between each application is 7-10 days.

[0024] Beneficial effects:

[0025] (1) The composite plant stress-resistant agent provided by the present invention contains polyglutamic acid and glycine betaine. On the one hand, the stress-resistant effect of the stress-resistant agent is improved after polyglutamic acid and glycine betaine are mixed. On the other hand, polyglutamic acid combines with the nitrogen atom on glycine betaine to form a stable composite system, which slowly and continuously provides glycine betaine to the plant. The combination of glycine betaine and polyglutamic acid can effectively promote the growth and development of crops, improve the utilization rate of the composite stress-resistant agent, and prolong the action time of the composite stress-resistant agent.

[0026] (2) The composite plant stress-resistant agent containing glycine betaine and polyglutamic acid of the present invention can significantly increase the yield of economic food crops such as corn, peanuts, celery, and grapes; under adverse environments such as drought, low temperature, and high salt, the application of the composite plant stress-resistant agent of the present invention can significantly increase the yield of crops under the same environment, and at the same time, it also increases the chlorophyll content, antioxidant enzymes, and expression levels of stress-resistant related genes in plant cells, reduces the malondialdehyde content, and thus promotes plant growth.

[0027] (3) The composite plant stress-resistant agent containing glycine betaine and polyglutamic acid of the present invention, except for glycine betaine, is all prepared by biological methods, is non-toxic, and is degradable, which meets the characteristics of environmentally friendly green agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0029] Figure 1 The infrared absorption spectra of polyglutamic acid, glycine betaine and the composite plant stress resistance agent prepared in Example 1 are shown; from left to right are polyglutamic acid, glycine betaine and the composite plant stress resistance agent.

[0030] Figure 2 The SEM electron microscope photographs are of polyglutamic acid, glycine betaine and the composite plant stress resistance agent prepared in Example 1; from left to right are polyglutamic acid, glycine betaine and the composite plant stress resistance agent.

[0031] Figure 3 The water contact angle images and numerical statistics of polyglutamic acid, glycine betaine and the composite plant stress resistance agent prepared in Example 1 are shown. DETAILED DESCRIPTION

[0032] The present invention is further described below based on the following examples. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0033] If the specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased through regular channels.

[0034] The formula of the modified Hoagland nutrient solution used in the following examples is: 6mM KNO3, 4mM Ca(NO3)2, 2mM NH4H2PO4, 1mM MgSO4, 0.050mM KCl, 0.025mM H3BO3, 0.002mM MnSO4, 0.002mM ZnSO4, 0.0005mM H2MoO4, 0.0005mM CuSO4 and 0.0128mM EDTA-Fe); the chemical components in the formula of 1 / 2 modified Hoagland nutrient solution are the same as those in the modified Hoagland nutrient solution, and the concentration of each substance is half of the concentration of the corresponding substance in the modified Hoagland nutrient solution.

[0035] Example 1 Preparation of composite anti-adverse agent

[0036] 30 g of glycine betaine and 30 g of polyglutamic acid were mixed in 1 L of 50% v / v ethanol aqueous solution to obtain a mixed solution, the pH of the mixed solution was adjusted to 5.0 with hydrochloric acid, and the mixed solution was treated with 60 kHz ultrasound for 30 min to obtain a reaction solution, and after the reaction was completed, anhydrous ethanol of the same volume as the reaction solution was added to the reaction solution, and a precipitate was obtained after sufficient stirring. The precipitate was collected by filtration, and dried at 60°C for 8 h to obtain a composite plant stress resistance agent.

[0037] Example 2 Characterization of polyglutamic acid and glycine betaine complex

[0038] (1) Infrared spectroscopy analysis

[0039] Infrared spectroscopy analysis of polyglutamic acid, glycine betaine and composite stress-resistant agent showed the following results: Figure 1 As shown, the infrared absorption peak of the composite stress-resistant agent is very similar to the characteristic infrared absorption peak of glycine betaine, which indicates that the composite of polyglutamic acid and glycine betaine is successfully prepared.

[0040] (2) Determination of C, H, O, and N element contents

[0041] The determination of C, H, O, and N element contents plays an important role in studying the elemental composition of substances and is an important analytical method for determining the molecular formula and structure of compounds. It is usually determined using an elemental analyzer. The C, H, O, and N element contents of polyglutamic acid, glycine betaine, and composite stress-resistant agent were determined. The results are shown in Table 1. The C, H, O, and N element contents of the composite stress-resistant agent are higher than those of polyglutamic acid (PGA) and lower than those of glycine betaine (GB). The composite is obtained by the mixed reaction of PGA and GB, so it is shown that the polyglutamic acid-glycine betaine (PGA-GB) composite was successfully prepared.

[0042] Table 1 Element percentages of polyglutamic acid, glycine betaine and composite stress-resistant agents

[0043]

[0044] (3) Scanning electron microscopy observation

[0045] The scanning electron microscopy observations of polyglutamic acid, glycine betaine and composite stress resistance agent were carried out. Figure 2 As shown in the figure (the magnification is 5000 times), it was found that the large molecular weight polyglutamic acid has a spatial network structure, and the small molecule glycine betaine fills the spatial holes of polyglutamic acid after combining with polyglutamic acid in the solution, confirming that glycine betaine and polyglutamic acid form a complex.

[0046] (4) Contact angle test

[0047] The contact angle refers to the angle between the solid-liquid interface, the liquid interior and the gas-liquid interface at the interface of solid, liquid and gas. The size of the contact angle can be used to measure the wettability of liquids and solid surfaces. The contact angle test was conducted on polyglutamic acid, glycine betaine and composite stress-resistant agent. The results are as follows: Figure 3 As shown, the contact angle of the composite stress-resistant agent solution is smaller than that of the polyglutamic acid and glycine betaine solutions. Therefore, the composite stress-resistant agent has better wetting ability and can be better adsorbed on the plant leaf surface, reducing the loss caused by rain erosion and improving the utilization rate of the stress-resistant agent.

[0048] Example 3 Application of composite stress-resistant agent in hydroponics of rice seedlings under salt stress.

[0049] The rice seedlings were used as experimental objects for hydroponic experiments. After the rice seeds were sterilized, they were placed on moistened absorbent gauze for seedling acceleration. After about 3 days, the whitened seeds were transferred to a hydroponic box (17 cm × 17 cm × 5 cm) and cultured in a light-shielded hydroponic environment at 25°C. After 5 days of culture, 1 / 2 modified Hoagland nutrient solution was used for light culture. After 7 days of culture at 25°C, the rice seedlings were adapted to the hydroponic environment (fresh nutrient solution was replaced every 72 hours during the period), and simulated salt stress culture was carried out in a nutrient solution containing NaCl (the concentration of NaCl in the nutrient solution was 100 mM), and a certain amount of polyglutamic acid, glycine betaine or the composite stress resistance agent of the present invention was added, 25°C, lighted for 16 hours per day, and continued to be cultured for 28 days (fresh nutrient solution was replaced every 72 hours during the period). This experiment has 7 treatment groups, each of which was repeated 3 times. The specific treatment group design is shown in Table 2. The growth conditions of rice in each treatment group are shown in Table 3, and the physiological conditions of rice in each treatment group are shown in Table 4.

[0050] Table 2 Experimental design of salt stress group

[0051]

[0052] Table 3 Rice growth status of each treatment group

[0053]

[0054] Note: The values ​​in the table are all average values

[0055] Table 4 Physiological conditions of rice in each treatment group

[0056]

[0057] The data in Table 3 show that under salt stress, compared with other treatment groups, after applying the composite stress-resistant agent prepared in Example 1, the plant height, root length and leaf area of ​​the plant were all increased; there was no significant difference between applying 100 ppm of the composite stress-resistant agent and applying 200 ppm of the composite stress-resistant agent, but both were better than applying 100 ppm of polyglutamic acid or 100 ppm of glycine betaine.

[0058] Malondialdehyde content is a commonly used indicator in the study of plant stress resistance physiology. When plants are damaged under adversity, membrane lipid peroxidation often occurs. Malondialdehyde is the final decomposition product of membrane lipid peroxidation, and its content can reflect the degree of damage suffered by plants under adversity. The data in Table 4 show that under salt stress conditions, the malondialdehyde concentration of rice seedlings treated with composite stress-resistant agents was lower than that of the treatment groups treated with polyglutamic acid or glycine betaine alone and the control group (CK) to varying degrees, indicating that the composite stress-resistant agent exhibits good damage resistance and stress resistance.

[0059] Under salt stress conditions, the physiological conditions of rice seedlings treated with polyglutamic acid or glycine betaine were better than those without polyglutamic acid or glycine betaine. At the same time, the chlorophyll content of the composite stress-resistant agent under salt stress was higher than that of the treatment group treated with glycine betaine or polyglutamic acid alone and the control group, indicating that the composite stress-resistant agent exhibited a good function of promoting photosynthetic metabolism and was beneficial to the accumulation of organic matter.

[0060] Antioxidant enzymes SOD (superoxide dismutase), CAT (catalase) and POD (peroxidase) are the main enzymes in the plant antioxidant system, and their activity levels can reflect the degree to which plants are resistant to external adversity. Under salt stress conditions, the antioxidant enzyme activity of rice seedlings treated with polyglutamic acid or glycine betaine is significantly higher than that of rice seedlings not treated with polyglutamic acid or glycine betaine. At the same time, the antioxidant enzyme activity of rice seedlings treated with 100ppm composite stress-resistant agent is 14-32% higher than that of rice seedlings treated with only 100ppm polyglutamic acid or 100ppm glycine betaine, indicating that composite stress-resistant agent can improve the total antioxidant capacity of plants, enhance the stress resistance of crops, and ensure stable crop yields.

[0061] In summary, under salt stress conditions, both polyglutamic acid and glycine betaine have a growth-promoting effect on rice, but the growth-promoting effect of the composite stress-resistant agent obtained by combining the two is significantly better than that of either polyglutamic acid or glycine betaine alone.

[0062] Example 4 Application of the composite stress-resistant agent in hydroponics of rice seedlings under drought stress.

[0063] The rice seedlings were used as experimental objects for hydroponic experiments. After sterilization, the rice seeds were placed on moistened absorbent gauze for seedling acceleration. After about 3 days, the whitened seeds were transferred to a hydroponic box (17 cm × 17 cm × 5 cm) and cultured in a light-shielded hydroponic environment at 25°C. After 5 days of culture, 1 / 2 modified Hoagland nutrient solution was used for light culture. After 7 days of culture at 25°C, the rice seedlings were adapted to the hydroponic environment (fresh nutrient solution was replaced every 72 hours during the period), and cultured in a nutrient solution containing 200 g / L PEG (polyethylene glycol) to simulate drought stress, and a certain amount of polyglutamic acid, glycine betaine or the composite stress-resistant agent of the present invention was added, 25°C, lighted for 16 hours per day, and continued to be cultured for 28 days (fresh nutrient solution was replaced every 72 hours during the period). This experiment has 7 treatment groups, each of which is repeated 3 times. The specific treatment group design is shown in Table 5. The growth conditions of rice in each treatment group are shown in Table 6, and the physiological conditions of rice in each treatment group are shown in Table 7.

[0064] Table 5 Experimental design of drought stress group

[0065]

[0066] Table 6 Rice growth status of each treatment group

[0067]

[0068]

[0069] Note: The values ​​in the table are all average values

[0070] Table 7 Effects of each treatment on the physiological status of rice

[0071]

[0072] The data in Table 6 show that under drought stress, compared with other treatment groups, after applying the composite stress-resistant agent prepared in Example 1, the plant height, root length and leaf area of ​​the plant were all increased; there was no significant difference between applying 100 ppm of the composite stress-resistant agent and applying 200 ppm of the composite stress-resistant agent, but both were better than applying 100 ppm of polyglutamic acid or 100 ppm of glycine betaine.

[0073] The data in Table 7 show that under drought stress conditions, the malondialdehyde concentration of rice seedlings treated with the composite stress-resistant agent was lower than that of the treatment group treated with polyglutamic acid or glycine betaine alone and the control group (CK) to varying degrees, indicating that the composite stress-resistant agent exhibited good damage resistance and stress resistance.

[0074] Under drought stress conditions, the physiological conditions of rice seedlings treated with polyglutamic acid or glycine betaine were better than those without polyglutamic acid or glycine betaine. At the same time, the chlorophyll content of the composite stress-resistant agent under salt stress was higher than that of the treatment group treated with glycine betaine or polyglutamic acid alone and the control group, indicating that the composite stress-resistant agent exhibits a good function of promoting photosynthetic metabolism and is beneficial to the accumulation of organic matter.

[0075] Under drought stress conditions, the antioxidant enzyme activity of rice seedlings treated with polyglutamic acid or glycine betaine was significantly higher than that of rice seedlings not treated with polyglutamic acid or glycine betaine. At the same time, the antioxidant enzyme activity of rice seedlings treated with 100 ppm of the composite stress resister was 16-27% higher than that of rice seedlings treated with only 100 ppm of polyglutamic acid or 100 ppm of glycine betaine, indicating that the composite stress resister can improve the total antioxidant capacity of the plant, enhance the stress resistance of crops, and ensure stable crop yield.

[0076] In summary, under drought stress conditions, both polyglutamic acid and glycine betaine have a growth-promoting effect on rice, but the growth-promoting effect of the composite stress-resistant agent obtained by combining the two is significantly better than that of either polyglutamic acid or glycine betaine alone.

[0077] Example 5 Application of the composite stress-resistant agent in hydroponics of rice seedlings under low temperature stress.

[0078] The rice seedlings were used as experimental objects for hydroponic experiments. After sterilization, the rice seeds were placed on moistened absorbent gauze for seedling promotion. After about 3 days, the whitened seeds were transferred to a hydroponic box (17 cm × 17 cm × 5 cm) and cultured in a light-shielded hydroponic environment at 25°C. After 5 days of culture, 1 / 2 modified Hoagland nutrient solution was used for light culture. After 7 days of culture at 25°C, the rice seedlings adapted to the hydroponic environment (fresh nutrient solution was replaced every 72 hours during the period). The rice seedlings were transferred to an 8°C incubator to simulate low temperature stress, and a certain amount of polyglutamic acid, glycine betaine or the composite stress resistance agent of the present invention was added. The temperature was 8°C, and the light was 16 hours per day. The culture was continued for 28 days (fresh nutrient solution was replaced every 72 hours during the period). This experiment set up 7 treatment groups, each treatment group was repeated 3 times, and the specific treatment group design is shown in Table 8. The growth status of rice in each treatment group is shown in Table 9, and the physiological status of rice in each treatment group is shown in Table 10.

[0079] Table 8 Experimental design of low temperature stress group

[0080]

[0081] Table 9 Effect of each treatment group on rice growth

[0082]

[0083] Note: The values ​​in the table are all average values

[0084] Table 10 Physiological conditions of rice in each treatment group

[0085]

[0086] The data in Table 9 show that under low temperature stress, compared with other treatment groups, after applying the composite stress-resistant agent prepared in Example 1, the plant height, root length and leaf area of ​​the plant were all increased; there was no significant difference between applying 100 ppm of the composite stress-resistant agent and applying 200 ppm of the composite stress-resistant agent, but both were better than applying 100 ppm of polyglutamic acid or 100 ppm of glycine betaine.

[0087] The data in Table 10 show that under low temperature stress conditions, the malondialdehyde concentration of rice seedlings treated with the composite stress-resistant agent was lower than that of the treatment group treated with polyglutamic acid or glycine betaine alone and the control group (CK) to varying degrees, indicating that the composite stress-resistant agent exhibited good damage resistance and stress resistance.

[0088] Under low temperature stress conditions, the physiological conditions of rice seedlings applied with polyglutamic acid or glycine betaine were better than those without polyglutamic acid or glycine betaine. At the same time, the chlorophyll content of the composite stress-resistant agent under salt stress was higher than that of the treatment group applied with glycine betaine or polyglutamic acid alone and the control group, indicating that the composite stress-resistant agent exhibits a good function of promoting photosynthetic metabolism and is beneficial to the accumulation of organic matter.

[0089] Under low temperature stress conditions, the antioxidant enzyme activity of rice seedlings treated with polyglutamic acid or glycine betaine was significantly higher than that of rice seedlings not treated with polyglutamic acid or glycine betaine. At the same time, the antioxidant enzyme activity of rice seedlings treated with 100 ppm of the composite stress resister was 22-37% higher than that of rice seedlings treated with only 100 ppm of polyglutamic acid or 100 ppm of glycine betaine, indicating that the composite stress resister can improve the total antioxidant capacity of the plant, enhance the stress resistance of crops, and ensure stable crop yield.

[0090] In summary, under low temperature stress conditions, both polyglutamic acid and glycine betaine have a growth-promoting effect on rice, but the growth-promoting effect of the composite stress-resistant agent obtained by combining the two is significantly better than that of either polyglutamic acid or glycine betaine alone.

[0091] Example 6 Composite stress-resistant agent improves peanut yield

[0092] Field experiments were conducted with peanuts as the experimental object (crops were in a drought stress environment). Two treatment groups were set up in the experiment. One group was sprayed with water as the control group, and the other group was sprayed with a composite stress-resistant agent as the experimental group. The application method was: spray 15L of composite stress-resistant agent dilution (concentration of 100ppm) or water per mu each time, once every 7 to 10 days. During the experiment, other conditions of the two groups were the same. The peanut yields of the two treatment groups are shown in Table 11.

[0093] Table 11 Peanut yields of the two treatment groups

[0094]

[0095] As shown in Table 11, the compound stress-resistant agent has significantly improved plant weight, plant height and relative chlorophyll content compared with the blank control group. The experiment shows that the application of compound stress-resistant agent will increase plant weight to a certain extent, increase the chlorophyll content of plants under drought conditions, and promote plant growth, thereby achieving the purpose of increasing production.

[0096] Example 7 Composite stress resistance agent improves grape yield

[0097] A field experiment was conducted with grapes as the experimental object (the crop was in a high temperature stress environment, with the temperature greater than or equal to 35°C for more than 3 consecutive days). The experiment set up two treatment groups, one group sprayed with phosphorus and potassium fertilizer aqueous solution as the control group, and one group sprayed with phosphorus and potassium fertilizer aqueous solution containing composite stress resistance agent as the experimental group. The application method was: spray 15L of composite stress resistance agent dilution (100ppm) or phosphorus and potassium fertilizer aqueous solution per mu each time, once every 7 to 10 days. During the experiment, the other conditions of the two groups were the same. The peanut yields of the two treatment groups are shown in Table 12.

[0098] Table 12 Grape yields of the two treatment groups

[0099]

[0100] As shown in Table 12, the weight of grape bunches treated with the compound stress-resistant agent increased by 13.9% and the sugar content increased by 15.3% compared with those not treated with the compound stress-resistant agent. This shows that the compound stress-resistant agent has a good effect on increasing crop yield.

[0101] The present invention provides a composite plant stress resistance agent and its preparation ideas and methods. There are many methods and ways to implement the technical solution. 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 protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A composite plant stress resistance agent, characterized in that: The invention comprises a complex of glycine betaine and polyglutamic acid, wherein the mass ratio of the glycine betaine to the polyglutamic acid is 1:0.1-2.

2. The composite plant stress resistance agent according to claim 1, characterized in that: The polyglutamic acid can be replaced by polyglutamate salts, and the polyglutamate salts are any one or a combination of polyglutamate sodium salt, polyglutamate potassium salt, polyglutamate calcium salt, polyglutamate manganese salt, polyglutamate copper salt, polyglutamate zinc salt and polyglutamate iron salt.

3. The composite plant stress resistance agent according to claim 1, characterized in that: The molecular weight of the polyglutamic acid is greater than or equal to 700 kDa.

4. The method for preparing the composite plant stress resistance agent according to any one of claims 1 to 3, characterized in that: The polyglutamic acid or its solution is mixed with glycine betaine in ethanol to obtain a mixed solution, the pH of the mixed solution is adjusted to 3.0-6.0, ultrasonic reaction is performed to obtain a reaction solution, anhydrous ethanol is added to the reaction solution, the mixture is stirred, filtered, and the precipitate is dried to obtain the composite plant stress resistance agent.

5. The preparation method according to claim 4, characterized in that: The polyglutamic acid or its solution is mixed with glycine betaine in ethanol. When polyglutamic acid is used, the ethanol is a 50% v / v ethanol aqueous solution; when a polyglutamic acid solution is used, the amount of ethanol added is equal to the volume of the polyglutamic acid solution, and the ethanol is anhydrous ethanol.

6. The preparation method according to claim 4, characterized in that: The purity of the glycine betaine is greater than or equal to 98%; the polyglutamic acid is polyglutamic acid or its salt; The polyglutamic acid solution is any one or a combination of an aqueous solution of polyglutamic acid or its salt, a fermentation broth containing polyglutamic acid or its salt, and an aqueous solution of a dried product of the fermentation broth of polyglutamic acid or its salt; the concentration of the glycine betaine in the mixed solution is 10-50 g / L, and the concentration of the polyglutamic acid or its salt in the mixed solution is 1-100 g / L.

7. The preparation method according to claim 4, characterized in that: The amount of anhydrous ethanol added is equal to the volume of the reaction solution; the drying is performed at 50-80°C for 6-12 hours; the pH of the mixed solution is adjusted to 3.0-6.0 by using hydrochloric acid or sulfuric acid; the ultrasound has a frequency of 20-60kHz and a time of 10-60 minutes.

8. Use of the composite plant stress-resistant agent according to claim 1 in resisting adverse stress and promoting plant growth.

9. The use according to claim 8, characterized in that: The adverse stress is any one or a combination of high salt stress, low temperature stress, high temperature stress and drought stress; the plants are food crops and / or economic crops, preferably rice, peanuts, grapes, corn and celery.

10. The use according to claim 8, characterized in that: The method for using the composite plant stress-resistant agent is as follows: after the composite plant stress-resistant agent is prepared into a solution with a concentration of 50 to 200 ppm with water, it is applied by spraying on the leaves of crops or irrigating the roots, with an application amount of 10 to 30 L / mu each time and an interval of 7 to 10 days between each application.

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