Special preparation of ornithine in promoting growth of crops and its preparation method

Abstract

The application discloses a special preparation of ornithine in promoting growth of crops and a preparation method thereof. The special preparation comprises arginine grafted chitosan nanoparticles and proline and ornithine loaded on the nanoparticles, and the particle size of the nanoparticles is 120-220 nm. The preparation method comprises the following steps: grafting arginine on chitosan molecules, preparing nanoparticles by an ionic crosslinking method, and then physically adsorbing and loading proline and ornithine on the nanoparticles. Field tests show that the preparation of the application makes the 2-acetyl-1-pyrroline content of fragrant rice increase by 55.8% compared with a control; the yield increases by 18.5% compared with the control; the 2-AP high-temperature maintenance rate reaches 80.2% under high-temperature stress conditions; and the rain erosion resistance is significantly better than that of the control. The application has good popularization and application prospects, and has the advantages of simple components, environmental friendliness, high absorption efficiency, fragrance increasing, yield increasing and high-temperature stress resisting functions.

Description

Technical Field

[0001] This invention belongs to the field of plant growth regulator technology, specifically relating to a special formulation of ornithine for promoting crop growth and its preparation method. Background Technology

[0002] Fragrant rice is a special type of rice with a natural aroma, primarily composed of 2-acetyl-1-pyrroline (2-AP). In recent years, with the improvement of people's living standards, the demand for fragrant rice in both international and domestic markets has been increasing year by year. However, the production of fragrant rice has long faced the contradiction of high yield without fragrance, or fragrance without high yield. How to synergistically improve the yield and aroma quality of fragrant rice has become a key focus of agricultural science and technology research. The quality of fragrant rice is not only controlled by genetic factors but also influenced by environmental conditions and cultivation techniques, especially fertilization. Therefore, applying specialized fertilizers during the growth process of fragrant rice is particularly important for maintaining its excellent quality and increasing its yield.

[0003] Ornithine is a non-protein-derived basic nitrogenous compound that plays a crucial role in plant cell metabolism by participating in polyamine synthesis, urea cycling, and nitrogen metabolism. Studies have shown that ornithine is one of the important precursors of 2-acetyl-1-pyrroline (2-AP) in fragrant rice. Furthermore, ornithine transaminase plays a vital role in regulating nitrogen reuse in rice, contributing significantly to floret development and grain filling.

[0004] A patent for an organic aroma-enhancing foliar fertilizer for fragrant rice (application number: CN201711041468.5) discloses a compound foliar fertilizer containing γ-aminobutyric acid, pyrroline-5-carboxylic acid, and ornithine. When sprayed during the heading stage of fragrant rice, it can significantly increase the 2-AP content of brown rice, while also increasing yield, grain filling rate, and thousand-grain weight. However, the amino acids used are highly hydrophilic, making efficient transmembrane transport difficult. They are easily washed away by rainwater after spraying, resulting in a low actual utilization rate.

[0005] Patent CN120937867A discloses a flavor-enhancing scheme that combines proline and ornithine with nano-selenium and zinc oxide quantum dots, which achieved a 2-AP enhancement effect of approximately 44% in Luosha rice. However, its composition is complex, requiring the addition of inorganic nanomaterials such as nano-selenium and zinc oxide quantum dots, making the preparation process cumbersome, and the long-term ecological safety of nano-selenium is still unclear.

[0006] Furthermore, existing arginine-modified chitosan technology focuses on heavy metal adsorption and pharmaceutical delivery, and has not yet been applied to agricultural aroma enhancement. Current technologies do not adequately address the issue of aroma quality degradation in fragrant rice under high-temperature stress, and lack targeted solutions.

[0007] Therefore, developing a special formulation for enhancing the aroma and yield of fragrant rice that is simple in composition, environmentally friendly, highly absorbable, and also has the function of resisting high temperature stress has important industrial value. Summary of the Invention

[0008] The purpose of this invention is to provide a specific formulation of ornithine for promoting crop growth, and providing its preparation method is another objective of this invention. The specific formulation of this invention has simple components, is environmentally friendly, has high absorption efficiency, and also possesses resistance to high-temperature stress, effectively improving the aroma and yield of fragrant rice.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A specific formulation for promoting crop growth using ornithine, comprising arginine-grafted chitosan nanoparticles and proline and ornithine loaded thereon; the particle size of the arginine-grafted chitosan nanoparticles is 120-220 nm; the mass-volume concentration of proline in the formulation is 0.3-0.6 g / L, the mass-volume concentration of ornithine is 0.6-1.2 g / L, and the mass-volume concentration of arginine-grafted chitosan nanoparticles is 0.5-0.9 mg / mL.

[0010] Preferably, the arginine-grafted chitosan nanoparticles are prepared by ionic crosslinking of arginine-grafted chitosan, and the crosslinking agent is sodium tripolyphosphate.

[0011] Based on the same inventive concept, this invention further discloses a method for preparing a special formulation of ornithine for promoting crop growth, comprising the following steps: (1) Chitosan and L-arginine were grafted in the presence of EDC and NHS. The reaction conditions were pH 4-5, temperature 25-35℃, and time 10-12h. After the reaction was completed, the pH of the system was adjusted to 8.0 to precipitate the product. The product was purified by dialysis and freeze-dried to obtain arginine-grafted chitosan. (2) Dissolve the arginine-grafted chitosan obtained in step (1) in acetic acid solution to prepare a chitosan solution with a concentration of 0.6-0.8 mg / mL. Add sodium tripolyphosphate solution with a concentration of 0.4-0.6 mg / mL dropwise under stirring. The volume ratio of chitosan solution to sodium tripolyphosphate solution is 4:1-6:1. Stir at room temperature for 30-35 min and then disperse by ultrasonication to obtain an arginine-grafted chitosan nanoparticle colloidal solution. (3) After dissolving proline and ornithine, mix them with the nanoparticle colloidal solution obtained in step (2) and stir for 30-35 minutes to load the amino acids onto the nanoparticles.

[0012] Preferably, in step (1), the molar ratio of chitosan to L-arginine is 1:(0.8-1.2).

[0013] When applying the ornithine-specific formulation for promoting crop growth described in this invention to the aroma-enhancing and yield-increasing formulation for fragrant rice, it should be sprayed twice, once during the heading stage and once during the early grain-filling stage, with an interval of 8-9 days between each application. The optimal time for application is 28-40 hours before the onset of hot weather with a daily maximum temperature not lower than 35°C.

[0014] The core innovation of this invention lies in using arginine-grafted chitosan nanoparticles as delivery carriers for proline and ornithine, forming an integrated carrier-active ingredient formulation. The mechanism is as follows: This invention introduces guanidine groups through arginine grafting, significantly increasing the surface positive charge of the chitosan nanoparticles and enhancing their electrostatic binding with the negatively charged plant cell surface, thereby promoting the transmembrane transport of the nanoparticles and their loaded amino acids into the cell. The chitosan backbone of the nanoparticles possesses bioadhesive properties, forming a protective film on the leaf surface, delaying rainwater erosion and prolonging the action time of the active ingredients. The guanidine groups have strong antibacterial properties, preventing microbial degradation of amino acids after spraying and improving the stability of the formulation. The nanoparticles enable the slow release of the active ingredients, extending the action period.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses arginine-grafted chitosan nanoparticles to replace the nano-selenium and zinc oxide quantum dots in the prior art. It is made entirely of biodegradable materials, avoiding the potential ecological risks of inorganic nanomaterials. The composition is simple and environmentally friendly. 2. This invention utilizes arginine grafting to enhance the surface positive charge of chitosan nanoparticles, thereby strengthening the electrostatic binding with the negative charge on the plant cell surface and promoting the transmembrane transport of amino acids. Rain erosion tests show that the amino acid residue rate of the formulation of this invention is as high as 78.4%, more than double that of the carrier-free treatment. 3. Field trials showed that the formulation of this invention increased the 2-AP content of fragrant rice by 55.8% and the yield by 18.5% compared with the control. 4. Under natural high temperature conditions, the 2-AP high temperature retention rate of the formulation of this invention reaches 80.2%, providing an effective solution to the industrial problem of the decline in aroma of fragrant rice during the high temperature season; 5. The formulation of this invention significantly reduces the chalky grain rate and chalkiness, and increases the crude protein content, thereby achieving a simultaneous improvement in the processing quality and nutritional quality of rice. Detailed Implementation

[0016] The present invention will be further described below with reference to specific embodiments.

[0017] Example 1 This embodiment describes a special formulation of ornithine for promoting crop growth, wherein the concentration of proline is 0.4 g / L, the concentration of ornithine is 0.8 g / L, and the concentration of arginine-grafted chitosan nanoparticles is 0.7 mg / mL.

[0018] The preparation method of this formulation includes the following steps: (1) Take 2 g of chitosan with a degree of deacetylation of 86.4% and a viscosity-average molecular weight of 48,500 and disperse it in 100 mL of distilled water. Add 3.48 g of L-arginine, 3.83 g of EDC·HCl, and 2.30 g of NHS. Adjust the pH to 5.0 with 0.1 N hydrochloric acid and react at 30 °C for 12 h. After the reaction, adjust the pH to 8.0 with 0.5 N sodium hydroxide. Dialyze the mixture using a dialysis bag with a molecular weight cutoff of 3500 for 5 days, changing the water every 6 h. Freeze-dry to obtain arginine-grafted chitosan.

[0019] (2) Dissolve the above-mentioned arginine-grafted chitosan in 1% acetic acid solution to prepare a chitosan solution with a concentration of 0.7 mg / mL. Dissolve sodium tripolyphosphate in distilled water to prepare a sodium tripolyphosphate solution with a concentration of 0.5 mg / mL. Under magnetic stirring, add the sodium tripolyphosphate solution dropwise to the chitosan solution at a rate of 1 drop per second, with a volume ratio of chitosan solution to sodium tripolyphosphate solution of 5:1. Stir at room temperature for 30 min, sonicate for 2 min, and filter through a 0.45 μm filter membrane to obtain an arginine-grafted chitosan nanoparticle colloidal solution.

[0020] (3) Take 1000 mL of the prepared arginine-grafted chitosan nanoparticle colloidal solution, weigh 0.4 g of proline and 0.8 g of ornithine, dissolve them in 20 mL of distilled water, and slowly add the amino acid solution to the nanoparticle colloidal solution while stirring. Stir for 30 min, and then add distilled water to make up to 1000 mL. The concentration of proline in the obtained preparation is 0.4 g / L, the concentration of ornithine is 0.8 g / L, and the concentration of arginine-grafted chitosan nanoparticles is 0.7 mg / mL.

[0021] Example 2 This embodiment describes a specific formulation of ornithine for promoting crop growth. The formulation contains proline at a mass-to-volume concentration of 0.3 g / L, ornithine at a mass-to-volume concentration of 0.6 g / L, and arginine-grafted chitosan nanoparticles at a mass-to-volume concentration of 0.5 mg / mL. The preparation method is the same as in Example 1.

[0022] Example 3 This embodiment describes a special formulation of ornithine for promoting crop growth. In the formulation, the mass-volume concentration of proline is 0.6 g / L, the mass-volume concentration of ornithine is 1.2 g / L, and the mass-volume concentration of arginine-grafted chitosan nanoparticles is 0.9 mg / mL. The preparation method is the same as in Example 1.

[0023] Example 4 The ornithine preparation for promoting crop growth and its preparation method in this embodiment are the same as in Example 1, except that in step (1), the grafting reaction conditions are pH 4, temperature 25℃ and time 12h.

[0024] Example 5 The ornithine preparation for promoting crop growth and its preparation method in this embodiment are the same as in Example 1, except that in step (1), the grafting reaction conditions are pH 5, temperature 35℃ and time 10h.

[0025] Example 6 This embodiment describes a special formulation of ornithine for promoting crop growth and its preparation method, which is the same as in Embodiment 1, except that in step (2), the concentration of chitosan solution is 0.6 mg / mL, the concentration of sodium tripolyphosphate solution is 0.4 mg / mL, the volume ratio of chitosan solution to sodium tripolyphosphate solution is 4:1, and the mixture is stirred at room temperature for 30 min.

[0026] Example 7 The ornithine preparation for promoting crop growth and its preparation method in this embodiment are the same as in Example 1, except that in step (2), the concentration of chitosan solution is 0.8 mg / mL, the concentration of sodium tripolyphosphate solution is 0.6 mg / mL, the volume ratio of chitosan solution to sodium tripolyphosphate solution is 7:1, and the mixture is stirred at room temperature for 35 min.

[0027] Experimental Example Field Application Trial The experiment was conducted at a rice experimental base. The tested variety was fragrant rice. The experimental field soil was alluvial paddy soil with a pH of 6.8, an organic matter content of 25.6 g / kg, available nitrogen of 148 mg / kg, available phosphorus of 17.2 mg / kg, and available potassium of 95.8 mg / kg. Seedling raising, transplanting, and water and fertilizer management were carried out according to local high-yield cultivation technical specifications. The experiment included six treatments, each with three replicates, arranged in a randomized block design. Each plot was 30 square meters.

[0028] Control treatment CK: sprayed with clean water.

[0029] Treatment T1: Spray with a mixed aqueous solution of proline and ornithine, without adding any carrier. The concentration of proline is 0.4 g / L, and the concentration of ornithine is 0.8 g / L.

[0030] Treatment T2: Spray the formulation prepared in Example 1, namely arginine-grafted chitosan nanoparticles loaded with proline and ornithine, wherein the concentration of proline is 0.4 g / L and the concentration of ornithine is 0.8 g / L.

[0031] Treatment T3: Chitosan nanoparticles without arginine grafts were sprayed with proline and ornithine as a carrier control. The concentrations of proline and ornithine were the same as in T2.

[0032] Treatment T4: Arginine-grafted chitosan nanoparticles were sprayed but not loaded with proline and ornithine as a control for active ingredients.

[0033] All treatments were sprayed once during the heading stage and once during the early grain-filling stage. The heading stage spraying was carried out when 50% of the rice plants in the plot had headed, and the early grain-filling stage spraying was carried out 8 days after full heading. The spraying time was 4:30 pm on a sunny day, and the spraying volume was 250 liters per mu (approximately 0.067 hectares), which was evenly sprayed on the flag leaves and panicles of the rice plants.

[0034] During the experiment, a sustained period of high temperatures occurred on the 7th day after heading, with daily maximum temperatures reaching 36 to 38°C for 5 consecutive days. This provided natural conditions for assessing the high-temperature resistance of each treatment.

[0035] Five rice plants were collected from each plot at maturity, air-dried, and then used for seed testing to determine yield and yield components. 500 grams of paddy rice were collected from each plot, air-dried, stored for three months, hulled, and milled into brown rice for 2-AP content determination.

[0036] The 2-AP content was determined using solid-phase microextraction-gas chromatography-mass spectrometry (SPE-GC-MS). 2.0 g of brown rice flour was accurately weighed and placed in a 20 mL headspace vial, with 2-heptanol added as an internal standard. The aged SPE fiber was inserted into the headspace vial, and the mixture was equilibrated in a 70 °C water bath for 30 min, followed by extraction for 30 min. After extraction, the fiber was inserted into the gas chromatograph inlet, and desorption was performed at 250 °C for 3 min. The gas chromatographic conditions were: HP-5MS capillary column, high-purity helium as carrier gas. The mass spectrometry conditions were: EI ion source, electron energy 70 eV. Selected ion monitoring (MIM) mode was used. The qualitative ions for 2-AP were m / z 83 and m / z 111, and the quantitative ion was m / z 83. The qualitative ions for the internal standard 2-heptanol were m / z 83 and m / z 97. Quantification was performed using the internal standard method.

[0037] The free proline content was determined using the acidic ninhydrin colorimetric method. Proline dehydrogenase activity was determined using spectrophotometry, with proline as the substrate, to measure the NADH production rate at 340 nm.

[0038] The experimental results are shown in Table 1: Table 1. Experimental Results 1. Effects of each treatment on 2-AP content As shown in Table 1, the 2-AP content of the control treatment CK was 0.52 μg / g; the 2-AP content of treatment T1, which was sprayed with a mixed aqueous solution of proline and ornithine but without loading, was 0.67 μg / g, which was 28.8% higher than that of the control.

[0039] The 2-AP content of the formulation of Example 1 of this invention sprayed on treatment T2 was 0.81 μg / g, which was 55.8% higher than that of the control.

[0040] Treatment T3, sprayed with chitosan nanoparticles without arginine grafting but loaded with proline and ornithine, had a 2-AP content of 0.73 μg / g, which was 40.4% higher than the control but lower than T2's 55.8%, indicating that arginine grafting modification significantly contributes to the flavor enhancement effect. Treatment T4, sprayed with arginine-grafted chitosan nanoparticles but without proline and ornithine loading, had a 2-AP content of 0.58 μg / g, which was 11.5% higher than the control, indicating that the conversion of arginine itself can provide some substrate for 2-AP synthesis, but the effect is far lower than that of the treatment loaded with proline and ornithine.

[0041] 2. Effects of different treatments on 2-AP content under high temperature stress The high temperatures encountered during the experiment provided conditions for evaluating the high-temperature resistance of each treatment. Under sustained high temperatures after heading, the 2-AP content of each treatment decreased to varying degrees, but the magnitude of the decrease differed significantly. As shown in Table 2, the 2-AP content of the control treatment CK decreased to 0.31 μg / g under high-temperature stress, a decrease of 40.4% compared to normal temperature conditions. The 2-AP content of treatment T1 decreased to 0.46 μg / g under high-temperature stress, a decrease of 31.3% compared to normal temperature conditions. The 2-AP content of treatment T2 decreased to 0.65 μg / g under high-temperature stress, a decrease of only 19.8% compared to normal temperature conditions, with a high-temperature maintenance rate of 80.2%. This result is significantly better than other treatments, indicating that the formulation of this invention has good resistance to high-temperature stress. The 2-AP content of treatment T3 decreased to 0.54 μg / g under high-temperature stress, a decrease of 26.0% compared to normal temperature conditions. The 2-AP content of treatment T4 decreased to 0.41 μg / g under high-temperature stress, a decrease of 29.3% compared to normal temperature conditions. The above results indicate that the arginine-grafted chitosan nanoparticle carrier not only improves the delivery efficiency of amino acids, but also enhances the plant's heat resistance through the polyamine metabolic pathway by releasing arginine, thereby better maintaining the synthesis of 2-AP under high temperature stress.

[0042] 3. The impact of each treatment on yield Table 1 shows that the yield of the control treatment CK was 6.31 tons / ha, the yield of treatment T1 was 7.05 tons / ha, an increase of 11.7% compared to the control, the yield of treatment T2 was 7.48 tons / ha, an increase of 18.5% compared to the control, the yield of treatment T3 was 7.18 tons / ha, an increase of 13.8% compared to the control, and the yield of treatment T4 was 6.52 tons / ha, an increase of 3.3% compared to the control. Analysis of yield components indicates that the main reason for the increased yield in treatment T3 was the significant increase in thousand-grain weight and seed setting rate. The thousand-grain weight of treatment T3 was 22.86 grams, an increase of 7.2% compared to the control's 21.32 grams; the seed setting rate was 88.3%, an increase of 6.8 percentage points compared to the control's 81.5%.

[0043] 4. Effects of different treatments on physiological parameters of flag leaves during the grain-filling stage Fourteen days after heading, the free proline content and proline dehydrogenase activity of the flag leaves were measured. The control treatment (CK) had a free proline content of 152.3 μg / g and a proline dehydrogenase activity of 2.85 U / mg protein. Treatment T1 had a free proline content of 215.6 μg / g, an increase of 41.6% compared to the control; and a proline dehydrogenase activity of 3.72 U / mg protein, an increase of 30.5% compared to the control. Treatment T2 had a free proline content of 286.5 μg / g, an increase of 88.1% compared to the control; and a proline dehydrogenase activity of 4.86 U / mg protein, an increase of 70.5% compared to the control. Treatment T3 had a free proline content of 228.7 μg / g and a proline dehydrogenase activity of 3.85 U / mg protein. Treatment T4 had a free proline content of 178.2 μg / g and a proline dehydrogenase activity of 3.21 U / mg protein.

[0044] The above results indicate that the treatment of T3 in this invention significantly increased the accumulation of free proline and the activity of proline dehydrogenase in sword leaves, which is related to the metabolic regulation of proline absorption promoted by nanocarriers and the conversion of arginine to proline.

[0045] 5. Effects of each treatment on rice quality The results of rice quality testing are shown in Table 2: Table 2. Results of the effects of each treatment on rice quality. The control group (CK) had a head rice rate of 58.2%, a chalky grain rate of 16.8%, a chalkiness of 6.5%, and a crude protein content of 7.8%.

[0046] As shown in Table 2, treatment T1 had a head rice rate of 59.1%, a chalky grain rate of 14.2%, a chalkiness of 5.8%, and a crude protein content of 8.1%. Treatment T2 had a head rice rate of 60.3%, a chalky grain rate of 10.3%, a chalkiness of 4.2%, and a crude protein content of 8.8%. Treatment T3 had a head rice rate of 58.9%, a chalky grain rate of 13.8%, a chalkiness of 5.5%, and a crude protein content of 8.2%. Treatment T4 had a head rice rate of 58.4%, a chalky grain rate of 15.6%, a chalkiness of 6.1%, and a crude protein content of 7.9%. These results indicate that treatment T2 of this invention is most effective in reducing the chalky grain rate and chalkiness, and increasing the crude protein content, demonstrating that the formulation of this invention improves the processing quality and nutritional quality of rice while increasing aroma and yield.

[0047] 6. Effects of various treatments on the rain erosion resistance of the formulation To investigate the rain erosion resistance of different formulations, artificial rainfall was simulated 2 hours after spraying, with a rainfall intensity of 20 mm / h and a duration of 30 min. The residual amino acid content on the leaf surface before and after rainfall was measured, and the residue rate was calculated. The results are shown in Table 3 below.

[0048] Table 3. Results of the effects of each treatment on the rain resistance of the formulation. Table 3 shows that the amino acid residue rate of treatment T1 was 32.5%, indicating that amino acids without carrier protection are easily washed away by rainwater. The amino acid residue rate of treatment T2 was 78.4%, significantly higher than that of treatments T1 and T2, indicating that the arginine-grafted chitosan nanoparticle carrier has good adhesion properties on the leaf surface, effectively reducing losses caused by rainwater erosion. The amino acid residue rate of treatment T4 was 65.2%, lower than that of treatment T3, indicating that arginine grafting modification enhanced the electrostatic binding between the nanoparticles and the leaf, thereby improving the rain erosion resistance.

[0049] In summary, regarding 2-AP content, treatment T2 achieved 0.81 μg / g, a 55.8% increase compared to the control; regarding 2-AP content under high-temperature stress, treatment T2 achieved 0.65 μg / g, with a high-temperature maintenance rate of 80.2%; regarding yield, treatment T2 achieved 7.48 tons / hectare, an 18.5% increase compared to the control. Regarding free proline content, treatment T2 achieved 286.5 μg / g, a 20.2% increase compared to treatment T2. Regarding proline dehydrogenase activity, treatment T3 achieved 4.86 U / mg protein, a 16.3% increase compared to treatment T2. Regarding rain erosion resistance, treatment T2 had an amino acid residue rate of 78.4%, 2.4 times that of treatment T1 (32.5%).

[0050] The above experimental results demonstrate that the present invention achieves efficient delivery of proline and ornithine through arginine-grafted chitosan nanoparticle carrier technology. Furthermore, through the multiple biological functions of arginine, it outperforms existing technologies in terms of flavor enhancement, yield increase, resistance to high temperature stress, and rain erosion resistance, producing unexpected technical effects.

[0051] The principles of this invention can be varied and modified in many ways without departing from its spirit and scope, and all such variations and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A specific formulation of ornithine for promoting crop growth, characterized in that, This special formulation comprises arginine-grafted chitosan nanoparticles and proline and ornithine loaded thereon; the particle size of the arginine-grafted chitosan nanoparticles is 120-220 nm; in the formulation, the mass-volume concentration of proline is 0.3-0.6 g / L, the mass-volume concentration of ornithine is 0.6-1.2 g / L, and the mass-volume concentration of arginine-grafted chitosan nanoparticles is 0.5-0.9 mg / mL.

2. The specific formulation of ornithine for promoting crop growth according to claim 1, characterized in that, The arginine-grafted chitosan nanoparticles are prepared by ionic crosslinking of arginine-grafted chitosan, with sodium tripolyphosphate as the crosslinking agent.

3. A method for preparing a specific formulation of ornithine for promoting crop growth according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Chitosan and L-arginine were grafted in the presence of EDC and NHS. The reaction conditions were pH 4.5-5.5, temperature 25-35℃, and time 10-14h. After the reaction was completed, the pH of the system was adjusted to 8.0 to precipitate the product. The product was purified by dialysis and freeze-dried to obtain arginine-grafted chitosan. (2) Dissolve the arginine-grafted chitosan obtained in step (1) in acetic acid solution to prepare a chitosan solution with a concentration of 0.6-0.8 mg / mL. Add sodium tripolyphosphate solution with a concentration of 0.4-0.6 mg / mL dropwise under stirring. The volume ratio of chitosan solution to sodium tripolyphosphate solution is 4:1-6:

1. Stir at room temperature for 30-35 min and then disperse by ultrasonication to obtain an arginine-grafted chitosan nanoparticle colloidal solution. (3) After dissolving proline and ornithine, mix them with the nanoparticle colloidal solution obtained in step (2) and stir for 30-35 minutes to load the amino acids onto the nanoparticles.

4. The method for preparing the special formulation of ornithine for promoting crop growth according to claim 3, characterized in that: In step (1), the molar ratio of chitosan to L-arginine is 1:(0.8-1.2).

5. The application of the ornithine formulation according to any one of claims 1-2 in promoting crop growth in a formulation for enhancing the aroma and yield of fragrant rice, characterized in that, Spray twice during the heading stage and early grain-filling stage of rice, with an interval of 7-10 days between each spray.

6. The application according to claim 5, characterized in that, The best time to spray is 24-48 hours before the arrival of hot weather with a daily maximum temperature of no less than 35℃.

Images