Agricultural composition and application based on carbon quantum dots in improving photosynthesis of crops

Abstract

This application relates to the field of bio-agricultural technology, specifically disclosing an agricultural composition and its application based on carbon quantum dots to enhance crop photosynthesis. It is made from raw materials comprising the following parts by weight: 3-8 parts nitrogen-doped carbon quantum dots; 8-25 parts biostimulant; 1-4 parts wetting and dispersing agent; and 200-800 parts water. The nitrogen-doped carbon quantum dots are prepared by reacting aniline derivatives and biochar under a nitrogen atmosphere, followed by cooling to room temperature. Its application involves: S1, diluting the agricultural composition with water to the effective concentrations of carbon quantum dots and biostimulant; S2, applying the diluted agricultural composition to crop growth stages via foliar spraying or drip irrigation. The agricultural composition of this application can promote crop growth, increase biomass and yield, and has the advantages of ensuring uniform and stable dispersion of nitrogen-doped carbon quantum dots in solution and synergistically enhancing photosynthetic performance with biostimulant.

Description

Technical Field

[0001] This application relates to the field of bio-agricultural technology, and more specifically, to agricultural compositions and applications based on carbon quantum dots for enhancing crop photosynthesis. Background Technology

[0002] In the field of bio-agriculture, carbon quantum dots are mainly used as synergists for nano-fertilizers, plant growth regulators, and stress resistance inducers. Their tiny size and surface rich in functional groups enable them to efficiently penetrate plant cell walls, precisely deliver trace elements, and enhance photosynthetic efficiency, thereby improving crop yield and quality. At the same time, carbon quantum dots have low biotoxicity and high biocompatibility, and can achieve the slow release of nutrients such as nitrogen and phosphorus by regulating surface chemical properties, reducing fertilizer loss and environmental pollution. Their fluorescence properties also support real-time tracking of nutrient metabolism pathways within plants, providing a visual basis for precision agriculture.

[0003] The related carbon quantum dots achieve nutrient transport and photosynthesis enhancement through their nano-size and surface functional groups. However, they are prone to aggregation and inactivation in solution. At the same time, the wetting and spreading requirements of foliar application are not taken into account, resulting in poor stability, single function and low application efficiency in actual application, which limits their large-scale promotion in the field. Summary of the Invention

[0004] To address the issues of poor stability, limited functionality, and low application efficiency in practical applications caused by carbon quantum dots achieving nutrient transport and photosynthetic enhancement through their nanoscale size and surface functional groups, this application provides agricultural compositions and applications based on carbon quantum dots for enhancing crop photosynthesis.

[0005] In the first aspect, this application provides an agricultural composition based on carbon quantum dots for enhancing crop photosynthesis, using the following technical solution; An agricultural composition based on carbon quantum dots for enhancing crop photosynthesis is made from the following raw materials in parts by weight: 3-8 parts nitrogen-doped carbon quantum dots; 8-25 parts biostimulant; 1-4 parts wetting and dispersing agent; and 200-800 parts water. The method for preparing the nitrogen-doped carbon quantum dots is as follows: nitrogen-doped carbon quantum dots are prepared by reacting aniline derivatives and biochar in a nitrogen atmosphere and then naturally cooling to room temperature.

[0006] By adopting the above technical solution, and through the compounding of nitrogen-doped carbon quantum dots, biostimulants, wetting and dispersing agents, and water in specific weight ratios, the composition system can ensure that the carbon quantum dots are uniformly dispersed and remain stable in the solution, avoiding aggregation and failure. The biostimulants, in this ratio, can synergistically enhance the effects of the carbon quantum dots on the crops. The addition of the wetting and dispersing agent ensures the wetting and spreading of the pesticide solution on the leaf surface during subsequent foliar spraying, creating a prerequisite for the absorption of the active ingredients. Therefore, a stable, synergistic, and easy-to-apply liquid agricultural composition has been obtained, laying the foundation for subsequently improving crop photosynthesis.

[0007] Preferably, in the method for preparing nitrogen-doped carbon quantum dots, the reaction temperature is 170-190℃ and the isothermal reaction time is 8-10 hours.

[0008] By adopting the above technical solution, the process conditions, including precise temperature control and constant temperature reaction time, provide a suitable energy environment and reaction time for the carbonization and nitrogen doping of aniline derivatives and biochar raw materials. Under these conditions, the raw materials can undergo sufficient pyrolysis, polymerization, and surface passivation reactions to form nitrogen-doped carbon quantum dot cores with uniform size and good crystallinity. Sufficient reaction time ensures that nitrogen is stably doped into the carbon core structure through chemical bonds, thereby endowing the carbon quantum dots with strong visible light absorption and photocatalytic properties. This is the material basis for their subsequent photocatalytic performance and enhancement of plant photosystem activity. Therefore, nitrogen-doped carbon quantum dots with stable fluorescence performance and high photocatalytic activity were obtained.

[0009] Preferably, the biostimulant is selected from one or more of amino acids, humic acids, seaweed extracts, or microbial fermentation metabolites.

[0010] By adopting the above technical solutions, and selecting amino acids, humic acids, seaweed extracts, or microbial fermentation metabolites as biostimulants, these substances are all naturally sourced plant growth regulators and nutrient components. They can regulate plant physiological metabolism through different pathways. For example, amino acids can participate in protein synthesis as nutrients, humic acids can improve the root environment and nutrient absorption, seaweed extracts contain a variety of active substances, and microbial metabolites contain a variety of enzymes and hormone analogs. When these biostimulants are used in combination with carbon quantum dots with photocatalytic activity, they can work together on two levels: energy supply and metabolic regulation. On the one hand, carbon quantum dots enhance the efficiency of light energy capture and conversion through photocatalysis; on the other hand, biostimulants optimize metabolic flux within the plant, thereby synergistically promoting the synthesis, transport, and accumulation of photosynthetic products.

[0011] Preferably, the amino acid is one or more of glycine, glutamic acid, aspartic acid, proline, or lysine; the humic acid is one or more of fulvic acid, humic acid, or humic acid; the seaweed extract is one or more of alginic acid, seaweed polysaccharide, or seaweed oligosaccharide; and the microbial fermentation metabolite is Bacillus subtilis fermentation broth or lactic acid bacteria fermentation broth.

[0012] By adopting the above technical solutions, the specific small-molecule amino acids are easily absorbed by leaves and directly participate in chloroplast metabolic reactions; the specific humic acid components have moderate molecular weight and high physiological activity, which can enhance the crop's utilization of micronutrients; the specific seaweed extract is a natural plant immune inducer and growth promoter; the specific microbial fermentation broth contains abundant organic acids, peptides, and auxins and other metabolites; these specific material selections ensure that the biostimulant components have clear physiological functions, good water solubility and compatibility stability, are compatible with the carbon quantum dot solution system, and play their role as signaling molecules, nutrients or metabolic regulators after crop absorption, forming a biochemical complement with the physical photocatalytic effect of carbon quantum dots.

[0013] Preferably, the wetting and dispersing agent is selected from nonionic surfactants or anionic surfactants.

[0014] By adopting the above technical solution, nonionic or anionic surfactants are selected as wetting and dispersing agents. These two types of surfactants are widely used in agricultural formulations and have good compatibility with most pesticides and fertilizers. Their main function is to adsorb onto the surface of carbon quantum dot particles during the preparation stage, and prevent the nanoparticles from agglomerating and settling due to high surface energy through steric hindrance or electrostatic repulsion, thus maintaining the stability of the formulation during storage. During the application stage, they can reduce the surface tension of the liquid and enhance its wetting, spreading and adhesion ability on the waxy leaf surface of crops, thereby increasing the contact area and time between carbon quantum dots and biostimulants and the leaf surface, and promoting their absorption through stomata or cuticle.

[0015] Preferably, the nonionic surfactant is one or more of alkyl polysaccharide glycoside, fatty alcohol polyoxyethylene ether, or octylphenol polyoxyethylene ether; the anionic surfactant is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, or sodium lignosulfonate.

[0016] By adopting the above technical solutions, specific nonionic or anionic surfactants are selected, which are made from natural raw materials and have excellent emulsifying and wetting properties, while also possessing dispersion and film-forming characteristics. The aforementioned wetting and dispersing agents have definite chemical structures and properties, and can provide the composition with predictable physical stability and leaf spreading performance. They can coexist stably with the aforementioned carbon quantum dots and biostimulant solutions, and are safe for crops at conventional concentrations.

[0017] Preferably, the nitrogen-doped carbon quantum dots have a particle size of 3-8 nm and a fluorescence emission wavelength of 420-550 nm.

[0018] By adopting the above technical solution, the particle size of nitrogen-doped carbon quantum dots is controlled within a specific nanometer range. This size range is smaller than the intercellular spaces of plant cells, ensuring that carbon quantum dots can easily enter the interior of the leaf through stomata or epidermal penetration. The small size also endows carbon quantum dots with a large specific surface area and more surface active sites, which is beneficial to their photocatalytic reaction. At the same time, the fluorescence emission wavelength is within a specific spectral range, covering the blue to green light region, which matches the absorption spectrum of some pigments in plant photosynthesis and the transmitted light spectrum of leaves. This optical property means that carbon quantum dots can convert absorbed ultraviolet or short-wave visible light into longer-wavelength fluorescence, providing additional light energy for the lower chloroplasts, or promote the electron transfer efficiency near photosystem II through their photocatalytic properties, thereby enhancing the light energy capture and utilization efficiency of leaves from a physical optics perspective.

[0019] Secondly, this application provides the application of agricultural compositions based on carbon quantum dots in enhancing crop photosynthesis, using the following technical solution; The application of agricultural compositions based on carbon quantum dots to enhance crop photosynthesis includes the following steps: S1. Dilute the agricultural composition with water to the effective concentrations of carbon quantum dots and biostimulants; S2: Apply the diluted agricultural composition to the crop growth and development stages by foliar spraying or drip irrigation.

[0020] By adopting the above technical solution, the two-step application method of first diluting and then applying during the growth period ensures that the active ingredients act on the crop at a safe and effective concentration. The dilution operation in step S1 adjusts the high concentration of the composition stock solution to a field application concentration suitable for crop absorption. Step S2, which selects foliar spraying or drip irrigation, can achieve the supply of nutrients and functional components. Foliar spraying allows carbon quantum dots and biostimulants to act on the leaves, the main organs of photosynthesis. By choosing to apply the solution at the growth and development stage of the crop, and intervening during periods when the crop has a high demand for photosynthetic assimilates or active physiological metabolism, the technical effect can be realized.

[0021] Preferably, in step S1, the effective concentration of the carbon quantum dots is 25–150 mg / L, and the effective mass concentration of the biostimulant is 0.1–1.0%.

[0022] By adopting the above technical solution, the effective concentration of carbon quantum dots for field application is limited to a certain range, and the effective mass concentration of biostimulants is also limited to a certain range. This concentration range is a safe and effective window verified by experiments. If the concentration is below the lower limit, the number of carbon quantum dots is insufficient, making it difficult to form an effective cover on the leaf surface or exert a photocatalytic promoting effect in vivo. If the concentration is above the upper limit, the excessive concentration of nanoparticles will cause physical shading or physiological stress on leaf cells. Within a specific range, the concentration of biostimulants can provide physiological stimulation signals and nutritional supplementation while avoiding metabolic burden or cost waste caused by excessive concentration. This optimized concentration ratio ensures a balance between efficacy, safety, and economy in the composition. Therefore, application parameters that take into account efficacy, safety, and economy are obtained.

[0023] Preferably, in step S2, the crop growth and development node is at least one of the following stages: seedling stage, jointing stage, heading stage, flowering stage, or grain-filling stage, and the crop is at least one of corn, wheat, cotton, or soybean. By adopting the above technical solution, the application method is targeted and operable because it specifically defines the application period as several growth and development nodes and limits the crop types. At these nodes, the crops are in the vigorous growth or transition period of vegetative and reproductive growth, with a high demand for photosynthetic assimilates and active photosynthetic organ functions. When this composition is applied at this time, the effect of carbon quantum dots in improving light energy utilization efficiency can be used by the crops to build organs, while biostimulants simultaneously optimize metabolic flow, jointly promoting biomass accumulation and yield formation. The listed crops are all major field crops and have application value.

[0024] In summary, this application has the following beneficial effects: 1. Because this application uses an agricultural composition composed of nitrogen-doped carbon quantum dots, biostimulants, wetting and dispersing agents, and water, this composition system can ensure that the carbon quantum dots are uniformly dispersed and remain stable in the solution, avoiding aggregation and failure. At the same time, the biostimulants can produce a synergistic effect with the carbon quantum dots in this ratio. The wetting and dispersing agents ensure the wetting and spreading properties of the pesticide solution when sprayed on leaves. Therefore, a liquid agricultural composition with stable components, synergistic functions, and easy application is obtained, laying the foundation for improving crop photosynthesis.

[0025] 2. In this application, aniline derivatives and biochar are used as raw materials to prepare nitrogen-doped carbon quantum dots by reaction in a nitrogen atmosphere. The carbonization and nitrogen doping provide suitable energy and time to ensure that nitrogen is stably doped in the form of chemical bonds and to form carbon quantum dots with uniform size and good crystallinity. Therefore, nitrogen-doped carbon quantum dots with stable fluorescence performance and high photocatalytic activity are obtained, providing material guarantee for them to play the role of enhancing the activity of plant photosystems.

[0026] 3. The method of this application, by selecting biostimulants from natural sources such as amino acids, humic acids, seaweed extracts or microbial fermentation metabolites and combining them with carbon quantum dots, can achieve synergistic effects on both energy supply and metabolic regulation levels. That is, carbon quantum dots improve the efficiency of light energy capture and conversion, while biostimulants optimize the metabolic flow in the crop, thus achieving a synergistic effect of promoting the synthesis, transport and accumulation of photosynthetic products.

[0027] 4. This application controls the particle size of nitrogen-doped carbon quantum dots to the nanoscale, making them easy to enter the interior of leaves; at the same time, it tunes their fluorescence emission wavelength to the visible light range, which is well matched with the absorption spectrum of plant photosynthetic pigments. Thus, carbon quantum dots can not only penetrate efficiently through small size, but also enhance the light energy capture and utilization efficiency of leaves through their optical properties, creating conditions for improving photosynthetic efficiency.

[0028] 5. The application method of this application, by diluting the composition to a safe and effective concentration and applying it to the leaves or drip irrigation at key growth and development stages of crops such as corn and wheat, can intervene during the period when crops have a high demand for photosynthetic compounds, thus achieving the effect of increasing yield and improving quality while taking into account effectiveness, safety and economy. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the application of the agricultural composition based on carbon quantum dots proposed in this application in enhancing crop photosynthesis. Detailed Implementation

[0030] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] Technical concept: The related carbon quantum dots achieve nutrient transport and photosynthesis enhancement through their nano-size and surface functional groups. However, they are prone to aggregation and inactivation in solution. At the same time, the wetting and spreading requirements of foliar application are not taken into account, resulting in poor stability, single function and low application efficiency in actual application, which limits their large-scale promotion in the field.

[0032] This application discloses an agricultural composition and its application based on carbon quantum dots for enhancing crop photosynthesis; it is made from raw materials comprising the following parts by weight: 3-8 parts nitrogen-doped carbon quantum dots; 8-25 parts biostimulant; 1-4 parts wetting and dispersing agent; and 200-800 parts water; the method for preparing the nitrogen-doped carbon quantum dots is as follows: using aniline derivatives and biochar as raw materials, nitrogen-doped carbon quantum dots are prepared by reaction in a nitrogen environment, followed by cooling to room temperature; its application is as follows: S1, diluting the agricultural composition with water to the effective concentration of carbon quantum dots and biostimulant; S2, applying the diluted agricultural composition to the crop growth and development stages by foliar spraying or drip irrigation.

[0033] This application employs an agricultural composition formulated from nitrogen-doped carbon quantum dots, biostimulants, wetting and dispersing agents, and water. This composition system ensures that the carbon quantum dots are uniformly dispersed and remain stable in the solution, preventing aggregation and failure. At the same time, the biostimulants can produce a synergistic effect with the carbon quantum dots in this formulation. The wetting and dispersing agent ensures the wetting and spreading properties of the pesticide solution during foliar spraying. Therefore, a liquid agricultural composition with stable components, synergistic functions, and easy application is obtained, laying the foundation for improving crop photosynthesis.

[0034] Example 1: This example provides an agricultural composition based on carbon quantum dots for enhancing crop photosynthesis, made from the following raw materials in parts by weight: 3 parts nitrogen-doped carbon quantum dots; 8 parts biostimulant; 1 part wetting and dispersing agent; and 200 parts water.

[0035] The nitrogen-doped carbon quantum dots were prepared at a reaction temperature of 170℃ and a constant temperature reaction time of 8 hours. The biostimulants were glycine, glutamic acid, aspartic acid, proline, and lysine. The wetting and dispersing agent was an alkyl polysaccharide. The nitrogen-doped carbon quantum dots had a particle size of 3 nm and a fluorescence emission wavelength of 420 nm.

[0036] The application of the above-mentioned agricultural compositions based on carbon quantum dots in enhancing crop photosynthesis includes the following steps: S1. Dilute the agricultural composition with water to the effective concentrations of carbon quantum dots and biostimulants; The effective concentration of carbon quantum dots is 25 mg / L, and the effective mass concentration of biostimulants is 0.1%.

[0037] S2. Apply the diluted agricultural composition to the crop growth and development stages by foliar spraying or drip irrigation.

[0038] The crop growth and development stages include the seedling stage, jointing stage, heading stage, flowering stage, and grain-filling stage. The crops include corn, wheat, cotton, and soybean.

[0039] Example 2: This example provides an agricultural composition based on carbon quantum dots for enhancing crop photosynthesis, made from the following raw materials in parts by weight: 5.5 parts nitrogen-doped carbon quantum dots; 16.5 parts biostimulant; 2.5 parts wetting and dispersing agent; and 500 parts water.

[0040] The nitrogen-doped carbon quantum dots were prepared at a reaction temperature of 180℃ and a constant temperature reaction time of 9 hours. The biostimulants were fulvic acid, humic acid, black humic acid, alginic acid, seaweed polysaccharide and seaweed oligosaccharide. The wetting and dispersing agent was sodium dodecylbenzenesulfonate. The particle size of the nitrogen-doped carbon quantum dots was 5.5 nm and the fluorescence emission wavelength was 485 nm.

[0041] The above-mentioned application of agricultural compositions based on carbon quantum dots in enhancing crop photosynthesis includes the following steps: S1. Dilute the agricultural composition with water to the effective concentrations of carbon quantum dots and biostimulants; The effective concentration of carbon quantum dots was 87.5 mg / L, and the effective mass concentration of biostimulants was 0.55%.

[0042] S2. Apply the diluted agricultural composition to the crop growth and development stages by foliar spraying or drip irrigation.

[0043] The crop growth and development stages include the seedling stage, jointing stage, heading stage, flowering stage, and grain-filling stage. The crops include corn, wheat, cotton, and soybean.

[0044] Example 3: This example provides an agricultural composition based on carbon quantum dots for enhancing crop photosynthesis, made from the following raw materials in parts by weight: 8 parts nitrogen-doped carbon quantum dots; 25 parts biostimulant; 4 parts wetting and dispersing agent; and 800 parts water.

[0045] The nitrogen-doped carbon quantum dots were prepared at a reaction temperature of 190℃ and a constant temperature reaction time of 10 hours; the biostimulant was Bacillus subtilis fermentation broth and lactic acid bacteria fermentation broth; the wetting and dispersing agent was fatty alcohol polyoxyethylene ether; the particle size of the nitrogen-doped carbon quantum dots was 8nm and the fluorescence emission wavelength was 550nm.

[0046] The above-mentioned application of agricultural compositions based on carbon quantum dots in enhancing crop photosynthesis includes the following steps: S1. Dilute the agricultural composition with water to the effective concentrations of carbon quantum dots and biostimulants; The effective concentration of carbon quantum dots is 150 mg / L, and the effective mass concentration of biostimulants is 1.0%.

[0047] S2. Apply the diluted agricultural composition to the crop growth and development stages by foliar spraying or drip irrigation.

[0048] The crop growth and development stages include the seedling stage, jointing stage, heading stage, flowering stage, and grain-filling stage. The crops include corn, wheat, cotton, and soybean.

[0049] Comparative Example 1: This comparative example refers to the content of Example 1, except that the weight part of nitrogen-doped carbon quantum dots in the agricultural composition is 1 part, and the rest of the contents are the same as in Example 1.

[0050] Comparative Example 2: This comparative example refers to the content of Example 1, except that the biostimulant in the agricultural composition is 4 parts by weight, and the rest of the contents are the same as in Example 1.

[0051] Comparative Example 3: This comparative example refers to the content of Example 1, except that the reaction temperature for preparing the doped carbon quantum dots is 150°C, and the isothermal reaction time is still 8 hours. The rest of the content is the same as that of Example 1.

[0052] Comparative Example 4: This comparative example refers to the content of Example 1, except that the particle size of the nitrogen-doped carbon quantum dots is 1 nm, and the fluorescence emission wavelength is still tuned to around 420 nm. The rest of the content is the same as Example 1.

[0053] Comparative Example 5: This comparative example refers to the content of Example 1, except that in application step S1, the effective concentration of diluted carbon quantum dots is 10 mg / L, and the effective mass concentration of biostimulant is still 0.1%. The rest of the content is the same as in Example 1.

[0054] Comparative Example 6: This comparative example refers to the content of Example 1, except that in application step S1, the effective mass concentration of the diluted biostimulant is 0.05%, and the effective concentration of carbon quantum dots is still 25 mg / L. The rest of the content is the same as in Example 1.

[0055] Performance testing Sample preparation: The samples required for this performance test were prepared according to the formulations and preparation methods disclosed in Examples 1-3 and Comparative Examples 1-6 to obtain uniform, stable liquid agricultural composition samples without obvious particles or agglomerates. The samples were sealed and stored in light-proof containers for later use. All sample preparation processes were conducted under consistent operating conditions and environment.

[0056] Physical stability and leaf wetting performance testing of the compositions: First, physical stability testing was conducted. Each prepared agricultural composition sample was placed in a stoppered graduated cylinder and stored at 54℃ for 14 days, followed by freezing at 0℃ for 14 days. After each temperature cycle, the samples were restored to room temperature. The presence of stratification, precipitation, flocculation, or crystallization was observed and recorded. Second, leaf wetting performance testing was conducted. Referring to the guidelines for pesticide field efficacy trials, healthy, clean wheat leaves were selected. Using a professional contact angle meter, each sample solution and a water control were dropped onto the leaf surface. The static contact angle of the droplets on the leaf was measured, and the time required for complete spread was recorded to evaluate the effectiveness of the wetting and dispersing agent and the spreading properties of the pesticide solution on the leaf surface. In this test, physical stability observation followed the visual method of conventional formulation stability testing, and the contact angle measurement of leaf wetting performance was based on the national standard GB / T30693-2014 "Measurement of Contact Angle between Plastic Film and Water".

[0057] Table 1: Results of Physical Stability and Leaf Wetting Performance Tests

[0058] Optical and catalytic performance testing of nitrogen-doped carbon quantum dots: First, a fluorescence spectrophotometer was used to scan and record the fluorescence emission spectra of the nitrogen-doped carbon quantum dot samples prepared in each example under the same excitation wavelength to determine their maximum emission wavelength and fluorescence intensity. A reference method was used, with quinine sulfate as a standard, to determine their fluorescence quantum yield. Photocatalytic activity was evaluated through simulated photocatalytic degradation experiments. A certain amount of carbon quantum dots was dispersed in a Rhodamine B dye solution and irradiated under simulated sunlight. Samples were taken at certain time intervals, and the change in the intensity of the dye's characteristic absorption peak was measured using a UV-Vis spectrophotometer to calculate its degradation efficiency, thus characterizing its photocatalytic ability. In the optical performance testing, the fluorescence spectrum was measured according to industry-standard spectral testing methods, and the photocatalytic degradation rate was calculated according to the national standard GB / T23762-2009 "Test Method for Purification of Aqueous Solution Systems of Photocatalytic Materials".

[0059] Table 2: Results of Optical and Catalytic Performance Testing of Nitrogen-Doped Carbon Quantum Dots

[0060] Synergistic effect detection of the composition on crop photosynthesis and growth: Maize was selected as the test crop and cultivated under controlled greenhouse conditions; when the maize grew to the three-leaf stage, the stock solution of the agricultural composition of each example and comparative example was diluted according to the effective concentration described in the application steps; a water treatment was set as a blank control; each group of maize plants was uniformly treated by foliar spraying, with at least 3 replicates for each treatment; on the 7th and 14th day after treatment, a portable photosynthesis meter was used to measure the photosynthetic parameters such as net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration and transpiration rate of the fully expanded functional leaves at the top of the plant under the same light, temperature and humidity conditions; at the end of the experiment, the plant height, stem diameter, aboveground fresh weight and dry weight were measured; the measurement of photosynthetic parameters followed the instrument operation procedures and general plant physiology measurement methods, and the measurement of biomass adopted the standard agronomic cultivar method.

[0061] Table 3: Results of the detection of the effects of the composition on crop photosynthesis and growth

[0062] Characterization and spectral properties of carbon quantum dots: The morphology and dispersion state of nitrogen-doped carbon quantum dot samples prepared in each embodiment were observed using transmission electron microscopy. The size of at least 100 particles was randomly measured to statistically analyze their particle size and distribution range. The absorption spectrum of the samples in the wavelength range of 200 nm to 800 nm was scanned using ultraviolet-visible absorption spectroscopy to analyze their absorption characteristics. Combined with the obtained fluorescence emission spectra, it was analyzed whether there was any overlap between the absorption and emission spectra and the absorption spectra of plant photosynthetic pigments, thereby assessing their potential light energy capture and conversion capabilities. The preparation and observation of transmission electron microscopy samples were carried out in accordance with general characterization methods in materials science, and the acquisition and analysis of spectral data followed standard spectroscopic testing procedures.

[0063] Table 4: Characterization Results of Microstructure and Spectral Properties of Carbon Quantum Dots

[0064] The effects of different application stages on crop yield and quality were investigated: Wheat was selected as the test crop. Starting from the seedling stage, agricultural compound diluted to the specified effective concentration was sprayed on the leaves at various growth stages, including the seedling stage, jointing stage, heading stage, flowering stage, and grain-filling stage. A treatment group was established that was sprayed only once during the seedling stage, and a control group was sprayed with water throughout the entire growth process. All treatment groups had identical water and fertilizer management except for the spraying operation. After the wheat was fully mature, it was harvested in plots for seed evaluation. The number of effective spikes per plant, the number of grains per spike, and the thousand-grain weight were measured and recorded, and the theoretical yield was calculated. Simultaneously, the crude protein content of the grains was measured using a near-infrared grain analyzer to assess quality. The seed evaluation methods for yield components followed the agricultural industry standard NY / T1301-2007 "Technical Regulations for Crop Variety Testing - Grain Crops," and grain quality determination referenced the national standard GB5009.5-2016 "National Food Safety Standard - Determination of Protein in Food."

[0065] Table 5: Results of the detection of the effects of different application times on crop yield and quality

[0066] Example Conclusion: As can be seen from Examples 1-3 and Comparative Example 1, and Table 1, an appropriate amount of nitrogen-doped carbon quantum dots helps maintain the stability of the formulation system, enhances wetting and spreading on the leaf surface, and improves its light-harvesting and conversion capabilities, thereby synergistically promoting crop photosynthesis and ultimately achieving increased yield and improved quality.

[0067] Based on Examples 1-3 and Comparative Example 2, and in conjunction with Table 1, it can be seen that sufficient biostimulants have an effect on synergistically enhancing the physiological metabolic activity of crops, optimizing photosynthetic function, and improving nutrient absorption, and are components that promote growth, increase yield, and improve quality.

[0068] As can be seen from Examples 1-3 and Comparative Example 3, and Table 1, a suitable synthesis temperature for nitrogen-doped carbon quantum dots is the basis for obtaining ideal optical properties and high photocatalytic activity, ensuring their ability to efficiently capture and utilize light energy, thereby improving the effect on crop photosynthesis.

[0069] As can be seen from Examples 1-3 and Comparative Example 4, and Table 1, the appropriate particle size of carbon quantum dots is an important guarantee for them to exert their light function regulation role and leaf deposition performance, affecting their spreading behavior on plant leaves and their light energy absorption and conversion efficiency, thereby affecting their final effect on promoting crop growth.

[0070] Based on Examples 1-3 and Comparative Example 5, and in conjunction with Table 1, it can be seen that maintaining a sufficient effective concentration of carbon quantum dots during application is a condition for them to exert their light regulation and photosynthetic catalysis functions, enhance crop photosynthetic efficiency and biomass accumulation; if the concentration is too low, the gain effect will be limited.

[0071] As can be seen from Examples 1-3 and Comparative Example 6, and Table 1, maintaining a sufficient effective concentration of biostimulants during application is the basis for activating crop physiological metabolism, providing substrates and energy for photosynthesis, and producing synergistic effects with carbon quantum dots. Insufficient concentration will weaken the effect on crop yield and quality.

[0072] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An agricultural composition based on carbon quantum dots for improving photosynthesis in crops, characterized in that, It is made from raw materials containing the following parts by weight: 3-8 parts nitrogen-doped carbon quantum dots; 8-25 parts biostimulant; 1-4 parts wetting and dispersing agent; 200-800 parts water; the preparation method of the nitrogen-doped carbon quantum dots is as follows: using aniline derivatives and biocarbon as raw materials, nitrogen-doped carbon quantum dots are prepared by reaction in a nitrogen atmosphere, and then naturally cooled to room temperature. 2.The agricultural composition based on carbon quantum dots for improving photosynthesis of crops according to claim 1, wherein, In the method for preparing nitrogen-doped carbon quantum dots, the reaction temperature is 170-190℃ and the isothermal reaction time is 8-10 hours. 3.The agricultural composition based on carbon quantum dots for improving photosynthesis of crops according to claim 1, wherein, The biostimulant is selected from one or more of the following: amino acids, humic acids, seaweed extracts, or microbial fermentation metabolites. 4.The agricultural composition based on carbon quantum dots for improving photosynthesis of crops according to claim 3, characterized in that, The amino acid is one or more of glycine, glutamic acid, aspartic acid, proline, or lysine; the humic acid is one or more of fulvic acid, humic acid, or humic acid; the seaweed extract is one or more of alginic acid, seaweed polysaccharide, or seaweed oligosaccharide; and the microbial fermentation metabolite is Bacillus subtilis fermentation broth or lactic acid bacteria fermentation broth. 5.The agricultural composition based on carbon quantum dots for improving photosynthesis of crops according to claim 1, wherein, The wetting and dispersing agent is selected from nonionic surfactants or anionic surfactants.

6. The agricultural composition based on carbon quantum dots for enhancing crop photosynthesis according to claim 5, characterized in that, The nonionic surfactant is one or more of alkyl polysaccharide glycoside, fatty alcohol polyoxyethylene ether, or octylphenol polyoxyethylene ether; the anionic surfactant is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, or sodium lignin sulfonate.

7. The agricultural composition based on carbon quantum dots for enhancing crop photosynthesis according to claim 1, characterized in that, The nitrogen-doped carbon quantum dots have a particle size of 3–8 nm and a fluorescence emission wavelength of 420–550 nm.

8. The application of agricultural compositions based on carbon quantum dots in enhancing crop photosynthesis, characterized in that, The agricultural composition based on carbon quantum dots for enhancing crop photosynthesis as described in any one of claims 1-7 comprises the following steps: S1. Dilute the agricultural composition with water to the effective concentrations of carbon quantum dots and biostimulants; S2: Apply the diluted agricultural composition to the crop growth and development stages by foliar spraying or drip irrigation.

9. The application of the agricultural composition based on carbon quantum dots in enhancing crop photosynthesis according to claim 8, characterized in that, In step S1, the effective concentration of the carbon quantum dots is 25–150 mg / L, and the effective mass concentration of the biostimulant is 0.1–1.0%.

10. The application of the agricultural composition based on carbon quantum dots in enhancing crop photosynthesis according to claim 8, characterized in that, In step S2, the crop growth and development node is at least one of the following stages: seedling stage, jointing stage, heading stage, flowering stage, or grain-filling stage, and the crop is at least one of corn, wheat, cotton, or soybean.

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