Polyglutamic acid rare earth chelate fertilizer synergist as well as preparation method and application thereof

Abstract

The invention discloses a polyglutamic acid rare earth chelate fertilizer synergist and a preparation method and application thereof, and belongs to the technical field of fertilizers, the polyglutamic acid rare earth chelate fertilizer synergist is formed by chelating polyglutamic acid and rare earth elements; wherein the content of rare earth elements in the polyglutamic acid rare earth chelate is 0.90-5.20 wt%; the preparation method comprises the following steps: adding a polyglutamic acid aqueous solution into a metal salt aqueous solution containing rare earth elements for chelating, and then sequentially washing, filtering, drying and crushing to obtain the polyglutamic acid rare earth chelate. According to the invention, polyglutamic acid and rare earth elements are combined, so that the problem that the existing rare earth elements are easily solidified and inactivated by soil is solved, and the polyglutamic acid rare earth chelate fertilizer synergist prepared by the invention can protect the growth of plants in a drought environment and also has unexpected remarkable low-temperature-resistant activity.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizers, and in particular relates to a polyglutamic acid rare earth chelate fertilizer synergist, a preparation method and an application thereof. Background Art

[0002] Against the backdrop of increasingly urgent demands for sustainable agricultural development and ecological environmental protection, the functional limitations of traditional fertilizers are becoming increasingly apparent. Existing fertilizer technologies have the following core flaws:

[0003] 1. Low efficiency of rare earth element utilization:

[0004] Although rare earth elements have been shown to promote plant photosynthesis and enhance stress resistance, they are easily adsorbed and solidified by clay minerals, iron and manganese oxides, etc. in the soil when applied directly, resulting in low bioavailability and difficulty in exerting their effects.

[0005] 2. Insufficient ability to adapt to adversity:

[0006] Existing functional fertilizers mostly focus on single nutrient supply or simple growth promotion functions, lacking the ability to cope with extreme environments. For example, under drought conditions, traditional water-retaining agents can only maintain soil moisture through physical water absorption, and are unable to regulate key drought resistance mechanisms such as stomatal opening and closing and osmotic pressure balance from a plant physiological perspective. Under low temperature stress, commercially available cold-resistant agents have the disadvantages of a short half-life and are prone to causing premature plant aging, making them unable to provide long-term low-temperature protection.

[0007] 3. Poor synergy of composite functions

[0008] Existing attempts to produce multifunctional fertilizers through physical mixing have encountered problems such as antagonism between components and asynchronous release. For example, when rare earth elements are simply blended with organic matter, the rare earth ions are easily over-complexed by the organic ligands, which in turn reduces their biological activity.

[0009] Furthermore, patent publication number CN 119708480 A discloses a polyaspartic acid rare earth chelate and its applications. While this method, through the preparation of a polyaspartic acid rare earth chelate, organically combines the two, promoting crop growth and inducing crop disease resistance, has a high rare earth element content of 10-20 wt%. On the one hand, high rare earth element content is difficult to migrate in the soil and is easily adsorbed and solidified by soil particles, resulting in long-term residue. Rare earth elements can then accumulate in plants and animals through the food chain, ultimately posing a potential threat to human health. On the other hand, the market price of rare earth elements is high and fluctuates significantly due to supply and demand and geopolitical factors, affecting their market competitiveness. Therefore, this patent makes it difficult to effectively reduce the rare earth content while ensuring the stability of the chelate, and technological innovation is needed to overcome this limitation. Furthermore, the patent does not disclose the low-temperature resistance of the polyaspartic acid rare earth chelate.

[0010] Therefore, there is an urgent need to provide a new fertilizer synergist and a preparation method thereof, which can reduce the content of rare earth elements while ensuring the growth activity and quality of plants and enhancing the low temperature resistance of plants. Summary of the Invention

[0011] In response to the above technical problems, the present invention proposes a polyglutamic acid rare earth chelate fertilizer synergist, a preparation method and application thereof; that is, the present invention combines polyglutamic acid and rare earth elements, overcoming the problem that existing rare earth elements are easily solidified and inactivated by soil, and the polyglutamic acid rare earth chelate fertilizer synergist prepared by the present invention can protect the growth of plants in arid environments and also has unexpectedly significant anti-low temperature activity.

[0012] To achieve the above object, the present invention provides the following technical solutions:

[0013] One of the technical solutions of the present invention:

[0014] A polyglutamic acid rare earth chelate fertilizer synergist, which is prepared by chelating polyglutamic acid and rare earth elements;

[0015] Wherein, the content of rare earth elements in the polyglutamic acid rare earth chelate is 0.90-5.20wt%.

[0016] Optionally, the rare earth element is at least one of the lanthanide elements.

[0017] Furthermore, the rare earth element is lanthanum.

[0018] Optionally, the rare earth element content in the polyglutamate rare earth chelate is 0.91 wt% or 5.11 wt%.

[0019] The second technical solution of the present invention:

[0020] A method for preparing a polyglutamic acid rare earth chelate fertilizer synergist comprises the following steps:

[0021] First, dissolve the metal salt containing rare earth elements and polyglutamic acid in water respectively and stir evenly;

[0022] Then, the polyglutamic acid aqueous solution is added to the metal salt aqueous solution containing rare earth elements for chelation, and then washed with ethanol and water respectively, and then filtered, dried and crushed to obtain the polyglutamic acid rare earth chelate.

[0023] Optionally, the metal salt containing a rare earth element is lanthanum nitrate hexahydrate.

[0024] Furthermore, the ratio of the metal salt to water in the aqueous solution of the metal salt containing rare earth elements is: 0.043-0.217 g: 5 mL; and / or,

[0025] Furthermore, the usage ratio of polyglutamic acid to water in the polyglutamic acid aqueous solution is: 1.3 g: 20 mL.

[0026] Optionally, the conditions during the chelation process are:

[0027] The reaction was stirred at room temperature for 4 h.

[0028] Optionally, the rotation speed during the stirring process is 50-150 r / min, preferably 100 r / min.

[0029] Optionally, the drying may be performed until constant weight is achieved.

[0030] The third technical solution of the present invention:

[0031] The invention discloses an application of a polyglutamic acid rare earth chelate fertilizer synergist in promoting plant growth activity and quality and enhancing plant low temperature resistance.

[0032] Optionally, during the application process, the seeds are soaked in an aqueous solution of a polyglutamic acid rare earth chelate fertilizer synergist for pretreatment.

[0033] Furthermore, the seeds are wheat seeds or corn seeds.

[0034] Optionally, the low temperature for enhancing the low temperature resistance of plants is 0-(-15)°C.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] 1. The polyglutamic acid rare earth chelate disclosed in the present invention has significantly better biological activity than the polyaspartic acid rare earth chelate when the rare earth element is chelated at a chelation ratio of 0.90-5.20 wt% (corresponding to a planned chelation ratio of 1-5%).

[0037] 2. The present invention sets up a drought test. By comparing the tests of three samples of polyglutamic acid rare earth chelate, rare earth metal salt and polyglutamic acid on wheat under drought conditions, it is proved that polyglutamic acid rare earth chelate can better maintain the growth activity and momentum of wheat under drought environment, and has a synergistic enhancement mechanism.

[0038] 3. The present invention also provides a low temperature resistance activity test. Through the corn low temperature seed germination test, it is proved that the polyglutamic acid rare earth chelate disclosed in the present invention has significant low temperature resistance activity. The relevant treatment can protect the normal germination of corn seeds at a lower temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 This is the chelation reaction equation of polyglutamic acid and rare earth elements of the present invention. DETAILED DESCRIPTION

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0044] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0045] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0046] The present invention discloses a method for preparing a polyglutamic acid rare earth chelate, comprising the following steps:

[0047] Weighing rare earth element metal salt and polyglutamic acid for later use;

[0048] The rare earth elements and polyglutamic acid are dissolved in water respectively, stirred evenly at a speed of 100 r / min, the polyglutamic acid aqueous solution is added to the rare earth element aqueous solution and mixed to carry out a chelation reaction, and then washed with ethanol and water respectively, and then filtered, dried and crushed to obtain a polyglutamic acid rare earth chelate.

[0049] The invention also discloses a polyglutamic acid rare earth chelate fertilizer synergist, which is prepared by the above preparation method.

[0050] In addition, the test method for the chelation ratio of lanthanum polyglutamate chelate is as follows:

[0051] Detection method: Take 0.1g of chelate, dissolve it with 5mL of nitric acid, 3mL of hydrofluoric acid and 2mL of hydrochloric acid, pour it into a microwave digestion tank, and perform microwave digestion according to the microwave digestion program: the first stage is set at a temperature of 120℃ and a pressure of 1.52×10 6 Pa, power 1000W for 4 min; the second stage temperature was set at 150℃ and pressure 1.82×10 6 Pa, power 1000W for 4 min; the third stage was set at 180℃ and pressure 2.43×10 6 Pa, power 1000W, digestion for 4 minutes. After digestion, set the temperature of the hot plate to 260℃ to remove the acid until it is almost dry. If the solution is still yellow, add a small amount of distilled water and repeat until the solution is colorless and transparent. Then transfer the digested sample to a PET bottle, add ultrapure water to the scale, filter through a 0.45μm microporous filter membrane, and store at low temperature (refrigerated at 5℃) until testing.

[0052] The element content was determined by ICP-MS. The instrument operating conditions were: radio frequency power 1550W, plasma gas flow rate 15L·min -1 , carrier gas flow rate 1.0 L·min -1 , atomization chamber temperature 2 °C, sampling depth 7.0 mm, analysis time 0.1 s, repeated 3 times.

[0053] The mass chelation ratio of the polyglutamate lanthanum chelate can be calculated by testing the rare earth content obtained.

[0054] Figure 1 is the chelating reaction equation of polyglutamic acid and rare earth elements of the present invention, wherein M 3+ It represents the ionic state of the rare earth element, n and n1 are positive integers ≥ 1, and n2 and n3 are arbitrary integers.

[0055] Unless otherwise specified, the "room temperature" in the present invention refers to 20-30°C.

[0056] The raw materials used in the present invention are all purchased from the market. Polyglutamic acid is provided by Guangxi Duodele Biotechnology Co., Ltd., with a molecular weight of more than 10,000 KD.

[0057] The technical solution of the present invention is further illustrated by the following examples.

[0058] Example 1

[0059] The preparation method of polyglutamic acid rare earth chelate comprises the following steps:

[0060] Weigh 1.3 g of polyglutamic acid and dissolve it in 20 mL of water to prepare a polyglutamic acid aqueous solution;

[0061] Weigh 0.217 g of lanthanum nitrate hexahydrate and dissolve it in 5 mL of water to prepare a rare earth salt solution;

[0062] Under stirring at room temperature, the rare earth salt solution was slowly added dropwise to the polyglutamic acid aqueous solution and stirred at room temperature for 4 h. Subsequently, 50 mL of ethanol was added to precipitate a white solid, which was filtered. 20 mL of distilled water was added to the solid product to dissolve it, and then 50 mL of ethanol was added. After the white solid precipitated, it was filtered and dried to obtain a white powder, which was polyglutamic acid lanthanum rare earth chelate (0.32 g).

[0063] Then, based on Example 1, a series of experiments were conducted, i.e., only the amount of lanthanum nitrate hexahydrate was changed (0.217 g, 0.173 g, 0.130 g, 0.087 g, 0.043 g), and the following samples were prepared, as shown in Table 1. The actual chelation ratio was obtained by the above-mentioned detection method.

[0064] Table 1

[0065] serial number Polyglutamic acid (g) Lanthanum nitrate hexahydrate (g) Planned chelation ratio Actual detection chelation ratio 1 1.3 0.217 5％ 5.11％ 2 1.3 0.173 4％ 4.18％ 3 1.3 0.130 3％ 2.93％ 4 1.3 0.087 2％ 2.06％ 5 1.3 0.043 1％ 0.91％

[0066] In Table 1, aqueous solutions of chelates No. 1 with a planned chelation ratio of 5% and No. 5 with a planned chelation ratio of 1% were respectively used as samples for the following effect verification process.

[0067] Comparative Example 1

[0068] The difference from No. 5 in Example 1 is that the polyglutamic acid in the raw material is replaced by polyaspartic acid of equal mass. Other preparation conditions and parameters are the same as in Example 1.

[0069] Comparative Example 2

[0070] The difference from Example 1 No. 1 is that the polyglutamic acid in the raw material is replaced by polyaspartic acid of equal mass. Other preparation conditions and parameters are the same as those in Example 1.

[0071] Comparative Example 3

[0072] A mixture of polyglutamic acid and lanthanum nitrate hexahydrate aqueous solution, wherein the concentration of lanthanum in the aqueous solution mixture is 1×10 - 5 mol / kg, and the concentration of polyglutamic acid was 0.139 g / kg.

[0073] Comparative Example 4

[0074] A mixture of polyglutamic acid and lanthanum nitrate hexahydrate aqueous solution, wherein the concentration of lanthanum in the aqueous solution mixture is 5×10 - 5 mol / kg, and the concentration of polyglutamic acid was 0.0278 g / L.

[0075] Comparative Example 5

[0076] A single aqueous solution of lanthanum nitrate hexahydrate, wherein the concentration of lanthanum nitrate hexahydrate is 1×10 -5 mol / L or 5×10 -5 mol / L.

[0077] Comparative Example 6

[0078] The invention relates to an aqueous solution of a single polyglutamic acid, wherein the concentration of the polyglutamic acid is 0.139 g / L or 0.0278 g / L.

[0079] Comparative Example 7

[0080] An aqueous solution of a single polyaspartic acid, wherein the concentration of the polyaspartic acid is 0.139 g / L or 0.0278 g / L.

[0081] Effect verification

[0082] Effect example 1: Wheat seed germination test

[0083] Wheat seeds (Zhengmai 379) were soaked in a 1% sodium hypochlorite solution for 5 hours to prevent mildew during germination. After washing three times with clean water, the seeds were placed in a petri dish. Experimental groups were soaked in aqueous solutions of polyglutamic acid lanthanum chelates containing varying rare earth element contents. Control groups were soaked in aqueous solutions of polyaspartic acid chelates containing varying rare earth element contents, as well as individual rare earth salts, polyglutamic acid, and polyaspartic acid. A blank control group was soaked in an equal volume of water. Soaking conditions were: a constant temperature of 25°C for 12 hours.

[0084] After soaking, the seeds were taken out and placed on filter paper to absorb excess water. They were then evenly sown into agar culture cups. Ten seeds were used for each treatment, and three parallel tests were conducted. The agar culture cups were then placed in a constant temperature box, maintaining a temperature of around 25°C and a humidity of over 95%. After 36 hours, the germination of the seeds was checked and the number of germinated seeds was recorded. The results are shown in Table 2:

[0085] Table 2 Seed germination of each experimental group

[0086]

[0087] From the above test results, it can be seen that the polyglutamic acid lanthanum chelate, at a lower concentration (equivalent to a lanthanum concentration of 1×10 -5 mol / L and 1×10 -5 mol / L) can have a good effect on promoting seed germination, while the seed germination promoting activity of polyaspartate lanthanum chelate, lanthanum nitrate hexahydrate, polyglutamic acid, polyaspartic acid, and a simple mixture of polyglutamic acid and lanthanum salts at corresponding concentrations is much lower than that of the polyglutamate lanthanum chelate of the present invention; and the relevant treatments are better than the clear water blank control.

[0088] Effect example 2: Wheat drought stress pot experiment

[0089] The wheat variety "Zhengmai 379" was selected, and the wheat seeds were treated with the seed treatment method of Effect Example 1. The seeds were placed in different treatment solutions and soaked for 12 hours. After germination and growth, they were transplanted into pots with a diameter of 20 cm at the three-leaf stage (5 seedlings per pot, the matrix was loam: vermiculite = 3:1, mass ratio). Two treatments were set: normal irrigation (relative soil moisture content 75% to 80%, CK) and mild drought (55% to 60%). All samples were treated with mild drought, and only the clear water control had normal irrigation treatment. Water was controlled by weighing method, and stress lasted for 12 days. Finally, the relative chlorophyll content (SPAD) and relative leaf water content (RWC) were measured, and the biomass was measured after the experiment. Each treatment was repeated 3 pots, and the greenhouse environment was controlled at 25℃ / 18℃ (day / night) and 12h / d of light.

[0090] 1. Determination of relative chlorophyll content (SPAD value):

[0091] Measuring tool: Chlorophyll meter (such as SPAD-502).

[0092] Select the fully expanded functional leaves on the upper part of the plant (avoiding the veins), measure 3 points on each leaf, and take the average value to represent the SPAD value of the single plant. 3 plants were measured in each pot, and the test was repeated 3 times.

[0093] 2. Determination of relative water content of leaves (RWC,%):

[0094] Fresh leaves (avoiding the main veins) were weighed for fresh weight (FW). They were immersed in distilled water for 4 hours until saturated, and the surface moisture was wiped off to measure the saturated fresh weight (TW). They were then dried at 65°C to constant weight to measure the dry weight (DW).

[0095] Calculation formula:

[0096]

[0097] The specific data of relative chlorophyll content (SPAD value) and relative leaf water content (RWC, %) are shown in Table 3.

[0098] Table 3 Relative chlorophyll content and relative water content of leaves in each experimental group

[0099]

[0100]

[0101] From the test results in Table 3, it can be seen that the polyglutamic acid lanthanum chelate, at a lower concentration (equivalent to a lanthanum concentration of 1×10 -5 mol / kg and 1×10 -5 mol / kg, polyglutamic acid concentration of 0.0278g / kg and 0.139g / kg) can have a good effect on enhancing the drought resistance of wheat, and can significantly increase the relative chlorophyll content and relative water content of wheat leaves under drought stress conditions. However, polyaspartic acid lanthanum chelate, lanthanum nitrate hexahydrate, polyglutamic acid, polyaspartic acid, and a simple mixture of polyglutamic acid and lanthanum salts at corresponding concentrations can increase the relative chlorophyll content and relative water content of wheat significantly lower than polyglutamic acid lanthanum chelate.

[0102] 3. Biomass (dry weight, g / plant) test method:

[0103] The plants were divided into aboveground and root parts, sterilized at 105°C for 30 minutes, and then dried at 80°C to constant weight. The weights were weighed and the average values were calculated. The data on biomass (aboveground) and biomass (root) are shown in Table 4.

[0104] Table 4 Statistics of plant biomass in each experimental group

[0105]

[0106]

[0107] From the test results in Table 4, it can be seen that the polyglutamic acid lanthanum chelate, at a lower concentration (equivalent to a lanthanum concentration of 1×10 -5 mol / kg and 1×10 -5 mol / kg, polyglutamic acid concentrations of 0.0278 g / kg and 0.139 g / kg) can have a good effect on enhancing the drought resistance of wheat and can significantly increase the biomass of wheat under drought stress conditions. However, the effects of polyaspartic acid lanthanum chelate, lanthanum nitrate hexahydrate, polyglutamic acid, polyaspartic acid, and a simple mixture of polyglutamic acid and lanthanum salts on increasing the biomass of wheat at corresponding concentrations are significantly lower than that of polyglutamate lanthanum chelate.

[0108] In summary, polyglutamate lanthanum chelate can significantly promote the drought resistance of wheat and has the potential to improve the drought resistance of crops. Relevant data show that polyglutamate lanthanum chelate has a synergistic effect, which is significantly better than using polyglutamic acid and lanthanum salts alone, or simply mixing polyglutamic acid and lanthanum salts.

[0109] Effect Example 3: Corn Seed Germination Test under Low Temperature Stress

[0110] This experiment used Meizhen 209 corn seeds to investigate the effects of low temperature stress on seed germination characteristics. The seeds were treated using the seed treatment method described in Example 1. The seeds were soaked in different treatment solutions for 12 hours. Five treatment groups were set up at 25°C (control), 0°C, -5°C, -10°C, and -15°C, with three replicates for each treatment. After soaking, the seeds were evenly distributed in Petri dishes lined with double-layer filter paper, with 20 seeds per dish. Except for the 25°C control group, which was placed directly in a constant-temperature incubator, the remaining treatment groups were placed in artificial climate chambers for 24 hours under the corresponding temperature stress. The temperature was then returned to 25°C, and the filter paper was replenished with distilled water daily to keep it moist. The number of germinations on day 7 was recorded (germination was considered complete when the radicle broke through the seed coat by ≥2 mm). Detailed data are shown in Table 5.

[0111] Table 5 Number of germinated corn seeds in each experimental group

[0112]

[0113]

[0114] From the test results in Table 5, it can be seen that the polyglutamic acid lanthanum chelate, at a lower concentration (equivalent to a lanthanum concentration of 1×10 -5 mol / kg and 1×10 -5 mol / kg, and polyglutamic acid concentrations of 0.0278g / kg and 0.139g / kg) showed good cold resistance. Among them, 1% and 5% lanthanum polyglutamic acid chelates showed the strongest cold resistance under low temperature stress, especially under extreme low temperature conditions, significantly improving seed germination rate.

[0115] In summary, the present invention can significantly improve the germination rate and cold resistance of corn seeds in low-temperature environments by forming a chelate by rationally mixing polyglutamic acid and lanthanum ions, providing a new solution for agricultural production.

[0116] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A polyglutamic acid rare earth chelate fertilizer synergist, characterized in that: Made by chelating polyglutamic acid and rare earth elements; Wherein, the content of rare earth elements in the polyglutamic acid rare earth chelate is 0.90-5.20wt%.

2. A polyglutamic acid rare earth chelate fertilizer synergist according to claim 1, characterized in that: The rare earth element is at least one of the lanthanide elements.

3. A polyglutamic acid rare earth chelate fertilizer synergist according to claim 2, characterized in that: The rare earth element is lanthanum.

4. A polyglutamic acid rare earth chelate fertilizer synergist according to claim 1, characterized in that: The rare earth element content in the polyglutamic acid rare earth chelate is 0.91 wt% or 5.11 wt%.

5. A method for preparing a polyglutamic acid rare earth chelate fertilizer synergist, characterized in that: The following steps are involved: A polyglutamic acid aqueous solution is added to a metal salt aqueous solution containing rare earth elements for chelation, and then washed, filtered, dried and crushed in sequence to obtain the polyglutamic acid rare earth chelate fertilizer synergist according to any one of claims 1 to 4.

6. The method for preparing a polyglutamic acid rare earth chelate fertilizer synergist according to claim 5, characterized in that: The metal salt containing rare earth elements is lanthanum nitrate hexahydrate.

7. The method for preparing a polyglutamic acid rare earth chelate fertilizer synergist according to claim 5, characterized in that: The ratio of the metal salt to water in the aqueous solution of the metal salt containing rare earth elements is: 0.043-0.217 g: 5 mL; and / or, The usage ratio of polyglutamic acid to water in the polyglutamic acid aqueous solution is: 1.3 g: 20 mL.

8. Use of the polyglutamic acid rare earth chelate fertilizer synergist according to any one of claims 1 to 4 in promoting plant growth activity and quality and enhancing plant low temperature resistance.

9. Use of a polyglutamic acid rare earth chelate fertilizer synergist according to claim 8 in promoting plant growth activity, quality and enhancing plant low temperature resistance, characterized in that: During the application process, the seeds are soaked in an aqueous solution of a polyglutamic acid rare earth chelate fertilizer synergist for pretreatment.

10. The use of a polyglutamic acid rare earth chelate fertilizer synergist according to claim 8 in promoting plant growth activity, quality and enhancing plant low temperature resistance, characterized in that: The low temperature for enhancing the low temperature resistance of plants is -15 to 0°C.

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