Application of micro-plastic subjected to ultraviolet aging treatment in promoting growth and development of soybean seedlings

Abstract

The invention relates to the technical field of environmental protection, and particularly discloses application of micro-plastic subjected to ultraviolet aging treatment in promoting growth and development of soybean seedlings, and the preparation process of the micro-plastic subjected to ultraviolet aging treatment is as follows: under the conditions that the temperature is 20-30 DEG C and the relative humidity is 50-70%, the micro-plastic is irradiated with ultraviolet light for 30-40 days, and the ultraviolet irradiation intensity is 90-110 [mu] w / cm < 2 >. The micro-plastic subjected to ultraviolet aging treatment provided by the invention is beneficial to promoting the growth and development of stems and roots of soybean seedlings, increasing the MDA content of root systems and relieving the toxic action of the micro-plastic on the soybean seedlings.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technology, and in particular to the application of ultraviolet-aged microplastics in alleviating the toxicity of microplastics to soybean seedlings. Background Art

[0002] In 2004, Thompson and others from the University of Plymouth in the UK published a paper in the journal Science on plastic fragments in marine waters and sediments, coining the term "microplastics," referring to plastic fragments and particles less than 5 mm in diameter. In reality, microplastics range in size from a few micrometers to several millimeters, forming a heterogeneous mixture of plastic particles with diverse shapes that are often difficult to distinguish with the naked eye. Microplastics primarily originate from contaminated sewage sludge and the weathering and degradation of plastic products such as plastic bottles and bags. Large quantities of microplastics have been detected in the environment, and once they enter the soil, they may pose a potential threat to soil health. While the rate at which microplastics decompose in soil remains unclear, research suggests their continued presence and accumulation are posing serious environmental risks.

[0003] Synthetic rubber is one of the most widely used materials in products such as automobile tires, hoses, footwear, and rubber bands. Automobile tire production is a major activity that uses both synthetic and natural rubber. Tires are composed of natural and synthetic rubber, fillers, oils, and vulcanizing chemicals. During vehicle operation, friction between tires and the road generates tiny colloidal particles, including plastic components. These particles, also known as tire wear particles (TWP), are a common potential source of pollution. Existing recycling methods for scrap tires, such as crushing, landfilling, or incineration, result in the direct release of TWP into the environment. In particular, industrial processing often involves simple mechanical crushing, which generates large quantities of TWP microparticles that are discharged directly into wastewater systems or exposed to the open air without undergoing any aging treatment. Combined with TWP emissions from normal wear during vehicle use, the total amount of tire wear particles entering surface water systems is significantly higher. These directly emitted TWP not only accumulates near the point of use but can also be transported long distances through atmospheric circulation, ultimately being detected in soil and water bodies in remote areas, posing a persistent pollution threat. As rubber tire wear particles, TWP is also subject to physical, chemical, and biochemical aging during its formation and exposure process. Furthermore, it is highly likely to enter farmland ecosystems through rainwater washout, causing serious damage to crops.

[0004] Therefore, it is necessary to explore new ways to alleviate the damage of TWP to farmland crops. Summary of the Invention

[0005] To explore a new approach to mitigate the harm of TWP to farmland crops, the present invention provides the use of ultraviolet-aged microplastics to promote the growth and development of soybean seedlings. The ultraviolet-aged microplastics provided by the present invention promote the growth and development of soybean seedling stems and roots, increase root MDA content, and mitigate the toxic effects of microplastics on soybean seedlings.

[0006] The present invention provides an application of ultraviolet-aged microplastics in promoting the growth and development of soybean seedlings. The preparation process of the aged microplastics is as follows: irradiating the microplastics with ultraviolet light for 30 to 40 days at a temperature of 20°C to 30°C and a relative humidity of 50% to 70% with an ultraviolet radiation intensity of 90 μw / cm 2 ~110μw / cm 2 The UV light irradiation distance is 20cm to 30cm.

[0007] The UV-aged microplastics obtained by treating aged microplastics by UV irradiation in the present invention can promote the growth and development of soybean seedling stems and roots, increase the MDA content of the root system, and alleviate the toxic effects of microplastics on soybean seedlings.

[0008] Furthermore, the mixture is stirred every 10 to 14 hours during the ultraviolet irradiation process.

[0009] Furthermore, UV-aged microplastics were used to promote the growth and development of soybean seedling stems.

[0010] Furthermore, UV-aged microplastics were used to promote the growth and development of soybean seedling roots.

[0011] Furthermore, UV-aged microplastics were used to increase the MDA content in soybean roots.

[0012] Furthermore, UV-aged microplastics are used to regulate soil pH.

[0013] Furthermore, the microplastic is rubber microplastic.

[0014] Furthermore, the rubber microplastics are tire wear particles.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The UV-aged microplastics obtained by treating aged microplastics by UV irradiation in the present invention can promote the growth and development of soybean seedling stems and roots, increase the MDA content of the root system, and alleviate the toxic effects of microplastics on soybean seedlings.

[0016] The present invention compares the effects of H2O2 and UV treatments on TWP microplastics, with H2O2-treated TWP microplastics being designated as H2O2-TWP and UV-treated TWP microplastics being designated as UV-TWP, and compares the effects of the aged microplastics prepared after the two treatments on the stem length of soybean seedlings. The results show that, compared with CK, among the three treatments, H2O2-TWP treatment significantly inhibits the effect on soybean stem length, with the soybean stem length reaching the minimum under this treatment; UV-TWP treatment significantly promotes soybean stem length. p <0.05.

[0017] The present invention compared the effects of H2O2-TWP and UV-TWP microplastics on the root growth of soybean seedlings. The results showed that the promoting effect of UV-TWP and TWP treatments was significantly higher than that of H2O2-TWP. The effect of UV-aged TWP microplastics on the surface area of soybean roots was significantly promoted. p <0.01, an increase of 69.9% compared to the CK group. Compared with the CK group, the soybean root volume in the UV-aged TWP microplastics treatment increased significantly by 72.1%.

[0018] The present invention also found that UV-TWP microplastics have a lower impact on soil pH than TWP, which is beneficial for maintaining a stable pH in the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 Scanning electron microscopy images and Fourier transform infrared spectra of TWP microplastics with different aging treatments; In the figure, A is the scanning electron microscopy image of TWP, H2O2-TWP and UV-TWP; B is the Fourier transform infrared spectra of TWP, H2O2-TWP and UV-TWP.

[0021] Figure 2 The effects of TWP microplastics with different aging treatments on the stem length of soybean seedlings; In the figure, A shows the effects of TWP, H2O2-TWP, and UV-TWP on the stem length of soybean seedlings; B shows the growth status of soybean seedlings after TWP, H2O2-TWP and UV-TWP treatments.

[0022] Figure 3The effects of TWP microplastics with different aging treatments on the root system of soybean seedlings; In the figure, A shows the effects of TWP, H2O2-TWP, and UV-TWP on the total root length of soybean seedlings; B is the effect of TWP, H2O2-TWP and UV-TWP on the root surface area of soybean seedlings; C is the effect of TWP, H2O2-TWP and UV-TWP on the root volume of soybean seedlings.

[0023] Figure 4 This is the effect of aged TWP microplastics on the MDA content of soybean seedling roots.

[0024] Figure 5 This is the effect of aged TWP microplastics on soil pH. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are conventional methods unless otherwise specified, and the materials, reagents, etc. used in the following embodiments can be obtained from commercial sources unless otherwise specified.

[0026] Example 1: Application of UV-aged microplastics in promoting the growth and development of soybean seedlings.

[0027] 1. Test Materials Tire wear particles, denoted as TWP particles, were purchased from Shaanxi Hongda Rubber Products Co., Ltd., with a specification of 125 μm and black color.

[0028] Tire wear particle pretreatment: Purchased TWP particles were sterilized by soaking them in alcohol for 1 minute, then rinsed multiple times with ultrapure water, dried at low temperature, and passed through a 120-mesh sieve before use to ensure a particle size of less than 125 μm. The microplastic raw materials used in the examples were all pretreated TWP particles and are referred to as TWP microplastics.

[0029] UV light source: UVA-340 lamp purchased from Shenzhen Guanhongya Optoelectronics Technology Co., Ltd., with a power of 40W, a length of 600mm, a diameter of 38mm, and an ultraviolet radiation intensity of 99μw / cm 2 .

[0030] 30% hydrogen peroxide solution was purchased from Tianjin Damao Chemical Reagent Factory, and the experimental water was ultrapure water.

[0031] 2. Test methods 1. TWP adopts UV aging and 30% hydrogen peroxide chemical aging treatment (1) UV aging: The aging box used for light aging was purchased from Suzhou Dabao Packaging Products Co., Ltd. After modification, it is 70 cm long, 30 cm wide, and 30 cm high. Four UVA-340 lamps are installed on the top and an exhaust fan is installed on the back. Because the lamps generate heat during use, causing the temperature to rise, the exhaust fan can promote air flow and maintain the temperature in the aging box. The sample is evenly spread in a container wrapped in tin foil and placed in the aging box. The tin foil reflects light to maximize the utilization of the light source. The present invention exposes TWP microplastics to air for aging treatment. The temperature of the UV aging box is maintained at 25°C during operation, and the relative humidity measured by the hygrometer is 60%. The sample is stirred every 12 hours and aged for 35 days. The microplastics treated with UV aging, that is, the TWP microplastics treated with UV, are marked as UV-TWP.

[0032] (2) 30% hydrogen peroxide chemical aging treatment: TWP microplastics were immersed in a 30% hydrogen peroxide solution for 35 days. Because rubber is hydrophobic, a small amount of anhydrous ethanol was added to the solution to ensure that the material was fully exposed to the hydrogen peroxide solution. The sample was stirred every 12 hours. A large amount of heat was released and bubbles were generated during the initial reaction, so it was stirred every 3 hours. TWP microplastics treated with 30% H2O2 by mass were labeled H2O2-TWP.

[0033] 2. Characterization of microplastics After 10 mg of original TWP microplastics, 10 mg of UV-TWP microplastics, and 10 mg of H2O2-TWP microplastics were sprayed with gold, the surface morphology of the MPs was analyzed using a scanning electron microscope. The functional group changes of the three microplastics were qualitatively analyzed using a Fourier transform infrared spectrometer with a wavelength range of 4000 cm -1 ~400cm -1 .

[0034] 3. Effects of different treatments of TWP microplastics on soybean seedlings Experimental Group Design: This example employed four treatments. The first group consisted of unaged tire wear microplastics, designated TWP; the second group consisted of hydrogen peroxide-aged tire wear microplastics, designated H2O2-TWP; the third group consisted of UV-aged tire wear microplastics, designated UV-TWP; and the fourth group served as a control treatment, devoid of any TWP microplastics.

[0035] The prepared TWP, H202-TWP, and UV-TWP were weighed on a scale, and 4% of the dry soil mass of microplastics was added as the experimental concentration according to the group. They were mixed evenly with the test soil, and the soil without any additives was used as the control group. The test soil selected in this example was organic nutrient soil, vermiculite, and perlite mixed in a mass ratio of 3:1:1 after passing through a 2mm sieve. The organic nutrient soil was purchased from Stanley Agricultural Group Co., Ltd.

[0036] Each treatment was replicated three times, with each replicate consisting of one pot. Five soybean seedlings were planted in each pot, for a total of 30 pots and 450 plants. The bottom of each pot was covered with a geotextile to prevent soil loss. Once all pots were filled, the soil moisture level was maintained at 10%.

[0037] The soybean seeds used in this experiment were Heilongjiang 690 pearl beans. The seeds were first vernalized and placed in a low-temperature environment at 4°C for 24 hours before removal. The seeds were then disinfected by soaking them in a hypochlorous acid solution for 30 seconds and then rinsed three times with ultrapure water to remove any surface hypochlorous acid. The disinfected seeds were then immersed in ultrapure water, gently stirred, and allowed to stand for 30 seconds. Any damaged seeds floating on the surface were skimmed off and this process was repeated several times. The remaining seeds were then soaked in ultrapure water for 12 hours. The fully hydrated seeds were then placed in Petri dishes lined with two layers of filter paper, 20 seeds per dish, and incubated in a GZP250 light incubator at 28°C. The GZP250 light incubator was purchased from Tianjin Test Instrument Co., Ltd. and operated on a dark:light cycle of 8:16, with a light intensity of level 3. Water was replenished in the Petri dishes to ensure the required moisture for germination. After seven days of germination, seedlings with similar germination patterns were selected for testing.

[0038] Indoor controlled experiments were conducted in a GZP250 light incubator at a constant temperature of 28 ± 2°C, a light cycle of 16:8 daylight hours, and a light intensity of level 6. Seedlings of equal germination potential were transplanted into 15 cm diameter pots, with five plants per pot and three replicates per treatment. The pots were watered daily in the morning and evening. The experiment lasted 35 days, with samples collected 35 days after the plants were transplanted to the soil.

[0039] Soybeans were harvested on the 35th day of cultivation. After sampling, the plant surface was gently rinsed several times with ultrapure water to remove any soil and dust without damaging the plant's appearance. After blotting the plant surface with filter paper, the stem and root were separated using a sharp, clean blade. Stem height and root length were measured and recorded using a ruler. Fresh weights of stems, leaves, and total aboveground parts were weighed and recorded using an analytical balance. Root morphology was analyzed using a root scanner and root image analysis software to analyze total length, surface area, and average diameter. After recording, the roots, stems, leaves, and other parts of the plant were individually sealed in envelopes and placed in an oven at 105°C for 30 minutes. The temperature was then adjusted to 65°C and dried for 48 hours to a constant weight. The corresponding dry weights were then weighed and recorded using an analytical balance.

[0040] 4. Effect of aged TWP microplastics on the MDA content of soybean seedlings.

[0041] Malondialdehyde content in plants was determined using the thiobarbituric acid method. Weigh 0.2 g of fresh soybean seedling roots, clean any surface stains, and dry with filter paper. Add 10 mL of pre-chilled pH 7.8 phosphate buffer twice to a pre-chilled mortar and pestle. Grind and extract with liquid nitrogen. Centrifuge at 10,500 rpm for 15 minutes at 4°C in a high-speed refrigerated centrifuge. The supernatant is the plant extract and stored at 4°C. First, prepare a 20% (w / v) trichloroacetic acid solution: weigh 20 g of trichloroacetic acid and dissolve it in distilled water to 100 mL. Then, weigh 0.5 g of thiobarbituric acid, dissolve it in 1 M NaOH, and dissolve it in the 20% (w / v) trichloroacetic acid solution to 100 mL to create a 0.5% (w / v) thiobarbituric acid solution.

[0042] Use a pipette to transfer 1.5 mL of the extract to a stoppered test tube. Add 2.5 mL of a 0.5% TBA solution by volume. For a control group, replace the extract with 1.5 mL of a pH 7.8 phosphate buffer. Mix thoroughly and place in a boiling water bath for 20 minutes. After cooling, centrifuge at room temperature at 4000 rpm for 15 minutes. Measure the OD value of the supernatant at wavelengths of 532 nm, 600 nm, and 450 nm. Calculate the OD value using the following formula:

[0043] C MDA =6.45×(OD 532 -OD 600 )-0.56×OD 450 (1); Among them, C MDA Indicates the concentration of MDA in the extracted enzyme solution, unit: μmol / L; OD 532OD is the optical density measurement at a wavelength of 532 nanometers. 600 OD is the optical density measurement at a wavelength of 600 nanometers. 450 Represents the optical density measurement at a wavelength of 450 nanometers.

[0044] MDA content = [C MDA ⅹV0 / (1000ⅹV)ⅹV1] / W (2); Wherein, MDA content refers to the content of MDA in plant tissue samples, μmol / gFW; C MDA represents the concentration of MDA in the extracted enzyme solution, μmol / L; V0 represents the volume of the reaction system, mL; V represents the amount of enzyme solution used in the determination, mL; V1 represents the total amount of extracted enzyme solution, mL; W represents the weight of the plant tissue sample, g.

[0045] 5. Determination of soil pH Soil pH was determined using the distilled water extraction method. First, KHC8H4O4 was dried at 105°C for 3 hours, 5.105 g was weighed, and the solution was dissolved in distilled water to 500 mL to obtain a standard buffer solution with a pH of 4.01. KH2PO4 was dried at 50°C for 2 hours, 1.695 g was weighed, and 1.765 g of anhydrous Na2HPO4 was dissolved in distilled water to 500 mL to obtain a standard buffer solution with a pH of 6.87. Finally, 1.9 g of Na2B4O710H20 was dissolved in distilled water to 500 mL to obtain a standard buffer solution with a pH of 9.18. All solutions were stored at 4°C until needed. All reagents were of analytical grade.

[0046] The soil to be tested was naturally air-dried and then passed through a 2 mm sieve. 5 g was weighed and placed in a 50 mL vial. 50 mL of ultrapure water was added and the solution was stirred on a magnetic stirrer for one minute to allow the soil to be fully dispersed in the water. The solution was allowed to stand for 30 minutes and the pH value was measured using a pH meter calibrated with a standard buffer solution.

[0047] 2. Test results 1. Characterization of microplastics like Figure 1As shown, the surface of aged rubber tire wear particles exhibits a rough, bumpy, and more wrinkled appearance. H2O2-aged TWP exhibits a more pronounced graininess than UV-aged TWP. The appearance of these grooves and crevices is likely related to the microstructure, mechanical strength, and the oxidizing properties of H2O2 and UV. From a morphological perspective, H2O2 exhibits a slightly more pronounced aging ability than UV. TWP undergoes continuous fragmentation and particle size reduction during aging, while its specific surface area increases. Fourier transform infrared (FTIR) spectroscopy reveals that TWP is a mixture of multiple components, potentially leading to sample inhomogeneity during processing. The presence of carbon black in TWP also interferes with spectroscopic analysis. The characteristic peaks of the FTIR spectra of TWP, H2O2-TWP, and UV-TWP microplastics are indistinct and indistinguishable, indicating that hydrogen peroxide and UV-induced aging have not affected the overall chemical structure of the TWP microplastics. The chemical structure remains relatively stable during aging, with no significant chemical degradation or functional group changes.

[0048] 2. Effects of aged TWP microplastics on soybean seedling stem length The results are as follows Figure 2 As shown, the soybean stem length of the CK group was 31.7 cm, and the soybean stem lengths under the H2O2-TWP, UV-TWP, and TWP treatments were 27.1 cm, 37.3 cm, and 27.8 cm, respectively. Compared with CK, among the three treatments, the H2O2-TWP treatment showed a significant inhibitory effect on soybean stem length, with the soybean stem length reaching the lowest value under this treatment; the UV-TWP treatment significantly promoted soybean stem length. p <0.05.

[0049] 3. Effects of aged TWP microplastics on root growth of soybean seedlings The results are as follows Figure 3 As shown in A, the one-way ANOVA showed that the three types of TWP microplastics had significant effects on the total length of soybean roots. p <0.01. The total root lengths of soybeans in the CK, H2O2-TWP, UV-TWP, and TWP treatments were 165.0 cm, 191.8 cm, 243.9 cm, and 227.0 cm, respectively. All three microplastics promoted the total root length of soybean plants. The total root length of soybeans in the H2O2-TWP, UV-TWP, and TWP treatments increased by 26.8 cm, 78.9 cm, and 62.0 cm, respectively, compared with the CK group. The promoting effects of the UV-TWP and TWP treatments were significantly greater than those of the H2O2-TWP.

[0050] The results are as follows Figure 3 As shown in Figure B, the root surface areas of soybeans under the CK, H2O2-TWP, UV-TWP, and TWP treatments were 35.3 cm 2、24.9cm 2 、60.0cm 2 、37.5cm 2 The one-way ANOVA showed that the effect of UV-aged TWP microplastics on the surface area of soybean roots was significantly promoted. p <0.01, a 69.9% increase compared to the CK group. Soybean root surface area reached its minimum in the H2O2-TWP treatment, decreasing by 29.4% compared to the CK. One-way ANOVA results showed no significant effect of hydrogen peroxide-aged or unaged TWP microplastics on soybean root surface area.

[0051] The results are as follows Figure 3 As shown in Figure C, the results of one-way ANOVA showed that UV-aged TWP microplastics had a significant effect on soybean root volume. p <0.05, while the effects of hydrogen peroxide-aged TWP and non-aged TWP microplastics on soybean root volume were not significant. The soybean root volume of the CK group was 0.40 cm 3 The root volumes of soybeans under H2O2-TWP, UV-TWP and TWP treatments were 0.24 cm 3 、0.69cm 3 , 0.37cm 3 The UV-aged TWP microplastics treatment increased significantly by 72.1% compared with the CK group, while the H2O2-TWP and TWP treatments decreased by 39.2% and 8.2% respectively compared with the CK group.

[0052] This shows that TWP microplastics UV aging treatment is beneficial to promoting the growth and development of soybean seedling roots.

[0053] 4. Effects of aged TWP microplastics on MDA content in soybean seedling roots The results are as follows Figure 4 As shown, the MDA content in soybean roots in the CK group was 29.4 nmol / g. Both TWP and H₂O₂-TWP microplastics treatments significantly increased MDA content in soybean roots compared to the CK group. While UV-TWP treatment also increased MDA content in soybean roots, the difference was not significant. This suggests that UV aging reduces the degree of peroxidative damage induced by TWP microplastics in soybean seedling roots and enhances antioxidant capacity.

[0054] 5. Impact of aged TWP microplastics on soil pH The results are as follows Figure 5As shown, the soil pH of the CK group was 6.23, and the soil pH after adding H2O2-TWP and UV-TWP was 6.17 and 6.21 respectively, while the soil pH dropped to 6.07 after adding TWP. The results of one-way analysis of variance showed that the H2O2-TWP and UV-TWP microplastic treatment groups had no significant effect on soil acidity and alkalinity compared with the control group, while the addition of unaged TWP significantly reduced the soil pH. p <0.01.

[0055] Example 2: Application of UV-aged microplastics in promoting the growth and development of soybean seedlings.

[0056] The experimental steps of Example 2 are the same as those of Example 1, except that: The preparation process of the UV-aged microplastics was as follows: irradiation with UV light for 40 days at a temperature of 20°C and a relative humidity of 70% with an UV irradiation intensity of 110 μw / cm 2 .

[0057] Example 3: Application of UV-aged microplastics in promoting the growth and development of soybean seedlings.

[0058] The experimental steps of Example 2 are the same as those of Example 1, except that: The preparation process of the UV-aged microplastics was as follows: irradiation with UV light for 30 days at a temperature of 30°C and a relative humidity of 50% with an UV irradiation intensity of 90 μw / cm 2 .

[0059] The ultraviolet-aged microplastics obtained in Example 2 and Example 3 also have a growth-promoting effect on soybean seedlings, indicating that ultraviolet-aged microplastics can alleviate the toxic effects of ordinary microplastics on soybean seedlings.

[0060] Although preferred embodiments of the present invention have been described, additional changes and modifications to these embodiments may occur to those skilled in the art once the basic inventive concepts become known.

[0061] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. The application of ultraviolet-aged microplastics in promoting the growth and development of soybean seedlings is characterized by: The preparation process of the UV-aged microplastics is as follows: the microplastic raw materials are irradiated with UV light for 30 to 40 days at a temperature of 20°C to 30°C and a relative humidity of 50% to 70%, with an UV irradiation intensity of 90 μw / cm 2 ~110μw / cm 2 The particle size of the microplastic raw material is 100 μm to 125 μm.

2. The use of the ultraviolet-aged microplastics according to claim 1 in promoting the growth and development of soybean seedlings, characterized in that: During the UV irradiation process, stir once every 10 to 14 hours.

3. The use of the ultraviolet-aged microplastics according to claim 1 in promoting the growth and development of soybean seedlings, characterized in that: UV-aged microplastics were used to promote the growth and development of soybean seedling stems.

4. The use of the ultraviolet-aged microplastics according to claim 1 in promoting the growth and development of soybean seedlings, characterized in that: UV-aged microplastics were used to promote the growth and development of soybean seedling roots.

5. The use of the ultraviolet-aged microplastics in promoting the growth and development of soybean seedlings according to claim 1, characterized in that: UV-aged microplastics were used to increase the MDA content in soybean roots.

6. The use of the ultraviolet-aged microplastics in promoting the growth and development of soybean seedlings according to claim 1, characterized in that: UV-aged microplastics are used to regulate soil pH.

7. The use of the ultraviolet-aged microplastics in promoting the growth and development of soybean seedlings according to claim 1, characterized in that: The microplastic raw material is rubber microplastic.

8. The use of the ultraviolet-aged microplastics in promoting the growth and development of soybean seedlings according to claim 7, characterized in that: The rubber microplastics are tire wear particles.

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