Controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance for corn

Abstract

The application discloses a corn special controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances, which comprises 1000 parts of nitrogen fertilizer, 5-10 parts of flavonoid nutrient signal substance microcapsules and 50-100 parts of coating material. The flavonoid nutrient signal substances and benzoic acid are dissolved in deionized water to obtain a signal substance solution with alkaline pH, a PLGA solution is slowly poured into the signal substance solution, homogenized and emulsified to obtain a water / oil type emulsion, under constant temperature water bath, polyvinyl alcohol solution is added into the water / oil type emulsion, homogenized and emulsified to obtain a water / oil / water type emulsion, the water / oil / water type emulsion is frozen and centrifuged, washed and freeze-dried to obtain the flavonoid nutrient signal substance microcapsules. Compared with traditional controlled-release fertilizers, the controlled-release nitrogen fertilizer can continuously release the signal substances into the soil during the corn growth, stimulate the growth and metabolism of the root system, promote the colonization of nitrogen-fixing microorganisms and improve the nitrogen utilization rate of the corn.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of controlled-release fertilizer, in particular to a corn special controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance. BACKGROUND

[0002] Corn has a large demand for nitrogen fertilizer, and the amount of nitrogen fertilizer absorbed during its growth accounts for more than one-third of all nutrients. The nitrogen requirement for corn production of 100 kg of grain is in the range of 2.5 to 4.0 kg. Excessive application of nitrogen fertilizer in traditional agricultural production leads to a large amount of unused nitrogen entering water bodies through surface runoff and leaching. According to statistics, about 20% of the nitrogen fertilizer in the world is ultimately discharged into the ocean every year, causing serious ecological problems such as eutrophication, algal blooms, and expansion of anoxic zones, which threaten marine biodiversity and fishery resources.

[0003] Controlled-release urea is a common nitrogen-containing fertilizer on the market and has been widely used in corn production. However, controlled-release urea releases fewer nutrients in the early stage, which may not meet the rapid demand of crops in the early growth stage, leading to nutrient deficiency in the early growth stage of crops. Long-term use of controlled-release urea may lead to accumulation of nitrogen in the soil, affecting soil health and the ecological environment. Adding signal substances to fertilizers is one of the effective ways to improve the nitrogen utilization efficiency of corn. However, most existing controlled-release nitrogen fertilizers are designed for all crops and are not specifically designed for the needs of corn, which to some extent reduces the utilization efficiency of nitrogen fertilizer by corn. In addition, traditional controlled-release materials are mostly petrochemical-based products, and their degradation process may cause secondary pollution to the soil and marine environment.

[0004] The global nitrogen cycle is largely driven by soil microbes, but plant root exudates can profoundly alter soil microbial communities and affect their nitrogen transformations, and detailed understanding of this process can help to improve the low nitrogen utilization rate and nitrogen pollution in agriculture. Root exudates are composed of a variety of organic compounds, including secondary metabolites and signal molecules, which are released by plants into the rhizosphere, which is chemically, biologically and physically affected by root growth and activity. Root exudates / chemical signal substances have multiple effects in plant growth and stress response, including improving the physical and chemical properties of rhizosphere soil, promoting plant nutrient absorption and utilization, and recruiting beneficial microbial groups. If flavonoid nutrient signal substances are added to controlled-release fertilizer, the plant roots have a tendency to absorb nutrients, increasing the chances of the roots being close to the nutrients and signal substances, and the presence of the microbial community recruited by flavonoids strengthens the underground communication, promoting interaction between the same or different species, so the plant roots can use the power of the rhizosphere microbial community to maximize the efficient use of flavonoids in time and space, promote the absorption of nitrogen and improve the utilization rate of nitrogen fertilizer. This approach can provide, maintain or improve plant nutrition while effectively improving fertilizer utilization by reducing fertilizer loss, achieving the goal of green high yield and high quality. However, flavonoids contain multiple phenolic hydroxyl groups, which makes them susceptible to oxidation in the presence of light, oxygen, heat and other environmental conditions, leading to structural changes and reduced activity. Therefore, a corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances needs to be designed to enhance the efficient absorption and utilization of nitrogen fertilizer by the roots, activate the function of soil microorganisms in mediating soil nitrogen transformation and cycling, and also avoid oxidation and activity reduction of flavonoids. SUMMARY

[0005] In view of the above prior art, the purpose of the present application is to provide a corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances. The present application uses flavonoids as nutrient signal substances, which are sprayed together with bio-based polyurethane and carboxymethyl cellulose sodium (CMC) on the surface of urea particles to obtain a corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances. Compared with traditional controlled-release fertilizers, the signal substances can be continuously released into the soil during corn growth, stimulating root growth and metabolism, promoting the colonization of nitrogen-fixing microorganisms, and improving the nitrogen utilization rate of corn.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect of the present application, a corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances is provided, which comprises the following raw materials by weight fraction:

[0008] Nitrogen fertilizer 1000 parts, flavonoid nutrient signal substance microcapsule 5-10 parts, and coating material 50-100 parts.

[0009] Preferably, the nitrogen fertilizer is urea particles.

[0010] Preferably, the flavonoid nutrient signal substance microcapsule is prepared by the following method:

[0011] (1) Dissolve flavonoid nutrient signal substance and benzoic acid in deionized water, adjust the pH to alkaline with lye to obtain a signal substance solution, dissolve polylactic acid-glycolic acid copolymer in dichloromethane to obtain a PLGA solution, slowly pour the PLGA solution into the signal substance solution, homogenize and emulsify, and then stir to obtain a water / oil emulsion;

[0012] (2) Dissolve polyvinyl alcohol in deionized water to obtain a polyvinyl alcohol solution, under constant temperature water bath, add the polyvinyl alcohol solution to the water / oil emulsion, homogenize and emulsify, and then stir to obtain a water / oil / water emulsion;

[0013] (3) Freeze centrifuge the water / oil / water emulsion under stirring to obtain a precipitate, then wash and freeze dry to obtain a flavonoid nutrient signal substance microcapsule.

[0014] Preferably, in step (1), the flavonoid nutrient signal substance is at least one selected from naringenin, rutin, and apigenin; the mass ratio of the flavonoid nutrient signal substance to benzoic acid is 3:1; the pH is adjusted to 11; the mass concentration of polylactic acid-glycolic acid copolymer in the PLGA solution is 1%; the volume ratio of the signal substance solution to the PLGA solution is 1:3; the homogenization speed is 10,000 rpm; the emulsification time is 5 min; the stirring speed is 500 rpm and the stirring time is 1 h.

[0015] Preferably, in step (2), the concentration of the polyvinyl alcohol solution is 10 g / L; the temperature of the constant temperature water bath is 95℃; the volume ratio of the polyvinyl alcohol solution to the water / oil emulsion is 2.5:1; the homogenization speed is 10,000 rpm; the emulsification time is 5 min; the stirring speed is 400 rpm and the stirring time is 10 h.

[0016] Preferably, in step (3), the stirring speed is 10,000 rpm; the freezing centrifugation temperature is -20℃; and the freeze drying is carried out at -80℃ for 10 h.

[0017] Preferably, the film coating material is obtained by mixing plant oil, isocyanate, and sodium carboxymethyl cellulose at a mass ratio of 6:5:5.

[0018] Preferably, the plant oil is castor oil.

[0019] Preferably, the corn special flavonoid nutrient signal substance-containing controlled-release nitrogen fertilizer is prepared by the following method:

[0020] The nitrogen fertilizer is preheated, the flavonoid nutrient signal substance microcapsules are added into the coating material and uniformly mixed, and are sprayed on the surface of the nitrogen fertilizer in multiple times, so that the corn special controlled-release nitrogen fertilizer containing the flavonoid nutrient signal substance is obtained after solidification.

[0021] Preferably, the preheating temperature is 75 DEG C, and the preheating time is 30 min; the spraying times are greater than or equal to 2.

[0022] Preferably, the hot air flow of the preheating is 380 m 3 / min; the spraying speed is 5 g / min; and the solidification time is 10 min.

[0023] In a second aspect of the present application, the corn special controlled-release nitrogen fertilizer containing the flavonoid nutrient signal substance is applied in at least one of the following 1) to 4):

[0024] 1) increasing the corn yield;

[0025] 2) increasing the total nitrogen and nitrogen absorption amount of the corn plant;

[0026] 3) increasing the nitrogen fertilizer utilization rate;

[0027] 4) increasing the relative abundance of the corn rhizosphere Paenibacillus triticisoli .

[0028] In a third aspect of the present application, the flavonoid substance is applied as the nutrient signal substance in at least one of the following 1) to 4):

[0029] 1) increasing the corn yield;

[0030] 2) increasing the total nitrogen and nitrogen absorption amount of the corn plant;

[0031] 3) increasing the nitrogen fertilizer utilization rate;

[0032] 4) increasing the relative abundance of the corn rhizosphere Paenibacillus triticisoli .

[0033] The flavonoid substance is selected from at least one of naringenin, rutin and apigenin.

[0034] Advantages of the present application:

[0035] (1) In the present application, the flavonoid substance is used as the nutrient signal substance, and is sprayed on the surface of the urea particles together with the bio-based polyurethane and sodium carboxymethyl cellulose (CMC) to obtain the corn special controlled-release nitrogen fertilizer containing the flavonoid nutrient signal substance.

[0036] (2) The bio-based polyurethane raw material used in the application has a wide source and low price, and can be recycled and finally degraded. Bio-based polyurethane is a multifunctional material with economic and environmental advantages. CMC is used to increase the adhesion and water retention capacity of the membrane shell due to its excellent water solubility, viscosity and water retention. Therefore, the controlled-release nitrogen fertilizer has a certain yield-increasing effect compared with the conventional fertilization treatment.

[0037] (3) Compared with traditional fertilizers and ordinary controlled-release nitrogen fertilizers, the corn special controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances prepared by the application can significantly improve the yield of corn and also improve the relative abundance of corn rhizosphere bacteria. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 : The corn yield of each group of treatments;

[0039] Figure 2 : The total nitrogen (a) and nitrogen uptake (b) of corn plants of each group of treatments;

[0040] Figure 3 : The nitrogen utilization rate of each group of treatments;

[0041] Figure 4 : The relative abundance of each group of treatments Paenibacillus triticisoli

[0042] Figure 5 : (a) Nutrient demand of corn at each period; (b) Nutrient release of MA7;

[0043] Figure 6 : The nutrient release rate of each group of treatments. DETAILED DESCRIPTION

[0044] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs.

[0045] As introduced in the background section, the presence of flavonoid recruited microbial community further strengthens the underground communication and promotes the interaction between the same or different species. The plant root system can maximize the use of flavonoids in time and space with the help of rhizosphere microbial community, promote the absorption of nitrogen and improve the nitrogen utilization rate. However, flavonoids contain multiple phenolic hydroxyl groups, which makes them easily oxidize in the environment of light, oxygen, heat, etc., resulting in structural changes and reduced activity.

[0046] ​Based on this, the purpose of the present application is to provide a corn special nitrogen controlled release fertilizer containing flavonoid nutrient signal substance. In plant physiology, nutrient signal substances are crucial for regulating plant nutrient uptake, transport and utilization, and they can respond to changes in soil nutrients and affect plant metabolism and growth through signal transduction pathways. However, these signal substances are easily affected by oxidative stress in the natural environment, leading to changes in their structure and loss of physiological activity. Benzoic acid has significant antioxidant properties and can be used as an effective protective agent to protect nutrient signal substances from oxidative damage. By microencapsulating nutrient signal substances, on the one hand, it prevents mutual reaction or degradation caused by direct contact of signal substances with urea, and on the other hand, it prevents internal nutrient signal substances from undergoing oxidative reactions with oxygen in the air, ensuring their stability, activity and functionality, and extending their shelf life. During storage and application, for powdered nutrient signal substances, microencapsulation can reduce flowability, achieve slow release, and improve utilization efficiency. Corn has different nitrogen requirements at different growth stages. Compared with water / oil or oil / water emulsion method, water / oil / water emulsion method can better encapsulate fertilizer components through oil-in-water and water-in-oil processes, so that the fertilizer components are more densely enclosed in the internal phase, reducing the loss and leakage of active ingredients during the emulsification process, thereby improving the encapsulation efficiency. Due to its special double emulsion structure, it is more conducive to slow and sustained release of fertilizer nutrients, and better meets the nutrient requirements of crops at different growth stages. The fertilizer coating material prepared by the water / oil / water emulsion method has stronger resistance to environmental factors. Studies have shown that nitrogen demand will increase sharply during the corn seedling stage (about 30 days). The corn special nitrogen controlled release fertilizer containing flavonoid nutrient signal substance of the present application has a release period of more than 40 days, releases not less than 40% of the nutrients in the first 20 days of corn growth, not less than 65% of the nutrients in the first 40 days, and not less than 80% of the nutrients in the first 80 days, effectively solving the problem of nitrogen deficiency of existing coated controlled release nitrogen fertilizer in the early growth period of corn. The corn special nitrogen controlled release fertilizer containing flavonoid nutrient signal substance prepared by the present application combines the synergistic characteristics of controlled release urea and nutrient signal substances. Compared with traditional controlled release nitrogen fertilizer, the corn special nitrogen controlled release fertilizer containing flavonoid nutrient signal substance can release nitrogen and continuously release signal substances into the soil at the same time. On the one hand, it can stimulate the efficient uptake and utilization of nitrogen fertilizer by corn roots, increasing the biomass of corn; on the other hand, it can modify corn roots and attract nitrogen-fixing microorganisms to promote plant-soil nitrogen cycling, improving nitrogen utilization efficiency. During the release period of fertilizer nutrients, the signal substance in the corn special nitrogen controlled release fertilizer containing flavonoid nutrient signal substance can stimulate plant uptake of fertilizer nutrients; as flavonoid signal substances are released, corn and Paenibacillus triticisoli nitrogen-fixing microorganisms establish a good symbiotic relationship, and the two work together to improve the nutrient utilization efficiency of corn.

[0047] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0048] The test materials used in the embodiments of the present application are all conventional test materials in the art and can be purchased through commercial channels.

[0049] Example 1: Preparation of corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances

[0050] (1) Preparation of flavonoid substance microcapsules by water / oil / water emulsion method

[0051] First, 3 g of naringenin and 1 g of benzoic acid were dissolved in 100 mL of deionized water, and the pH of the solution was adjusted to 11 with 1 mol / L NaOH to obtain a signal substance solution. PLGA was dissolved in 300 mL of dichloromethane to obtain a PLGA solution with a concentration of 1% (w / v). Then, the PLGA solution was slowly poured into the signal substance solution, emulsified with a homogenizer at 10000 rpm for 5 min, and then stirred with a magnetic stirrer at 500 rpm for 1 h to obtain a water / oil emulsion.

[0052] Under the condition of constant temperature water bath at 95℃, 10.0 g of polyvinyl alcohol was dissolved in 1000 mL of deionized water to obtain a PVA solution, and the PVA solution was added to the water / oil emulsion, emulsified with a homogenizer at 10000 rpm for 5 min, and then placed on a magnetic stirrer and stirred at a speed of 400 rpm for 10 h to obtain a water / oil / water emulsion.

[0053] The water / oil / water emulsion was frozen and centrifuged at a speed of 10000 rpm to obtain a precipitate, which was washed with deionized water three times, and then the precipitate was freeze-dried at -80℃ for 10 h using a freeze dryer to collect flavonoid nutrient signal substance microcapsules.

[0054] (2) 500 g of urea particles were placed in a continuously rolling coating machine and preheated at 75℃ for 30 min. Castor oil, isocyanate, and sodium carboxymethyl cellulose (CMC) were mixed in a mass ratio of 6:5:5 to obtain a coating material. 5 g of flavonoid nutrient signal substance microcapsules were added to 50 g of the coating material and mixed uniformly to obtain a mixed solution, which was sprayed onto the surface of the rolling urea particles and reacted and solidified. The coating machine speed was 35 rpm, the temperature was 75℃, the hot air flow was 380 m 3 / min, the spraying speed was 5 g / min, the reaction and solidification time of the coating material was 10 min, and the amount of coating material added each time was 1% of the mass of the urea. After solidification, the second spraying was continued, and the corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substances was obtained after solidification.

[0055] Example 2: Preparation of corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance

[0056] The difference from Example 1 is that naringenin is replaced by an equal amount of rutin. Finally, corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance is obtained.

[0057] Example 3: Preparation of corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance

[0058] The difference from Example 1 is that naringenin is replaced by an equal amount of apigenin. Finally, corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance is obtained.

[0059] Example 4: Preparation of corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance

[0060] The difference from Example 1 is that naringenin is replaced by an equal amount of naringenin + rutin (naringenin, rutin weight ratio 1:1). Finally, corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance is obtained.

[0061] Example 5: Preparation of corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance

[0062] The difference from Example 1 is that naringenin is replaced by an equal amount of naringenin + apigenin (naringenin, apigenin weight ratio 1:1). Finally, corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance is obtained.

[0063] Example 6: Preparation of corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance

[0064] The difference from Example 1 is that naringenin is replaced by an equal amount of rutin + apigenin (rutin, apigenin weight ratio 1:1). Finally, corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance is obtained.

[0065] Example 7: Preparation of corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance

[0066] The difference from Example 1 is that naringenin is replaced by an equal amount of naringenin + rutin + apigenin (naringenin, rutin, apigenin weight ratio 1:1:1). Finally, corn-specific controlled-release nitrogen fertilizer containing flavonoid nutrient signal substance is obtained.

[0067] Comparative Example 1

[0068] Castor oil, isocyanate, and sodium carboxymethyl cellulose (CMC) are used as the coating material to coat according to the method of step (2) of Example 1, and the coating amount is 2% of the weight of urea. Finally, controlled-release nitrogen fertilizer without signal substance is obtained.

[0069] Comparative Example 2

[0070] The difference from Example 1 is that in step (2), 5g of flavonoid nutrient signaling substance microcapsules are replaced with naringin (the amount of naringin added is the same as the mass of naringin contained in the flavonoid nutrient signaling substance microcapsules in Example 1). Finally, a controlled-release nitrogen fertilizer containing flavonoid nutrient signaling substances is obtained.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that in step (2), 5g of flavonoid nutrient signaling substance microcapsules are replaced with naringenin + benzoic acid (the amount of naringenin and benzoic acid added is the same as the mass of naringenin and benzoic acid contained in the flavonoid nutrient signaling substance microcapsules in Example 1). Finally, a controlled-release nitrogen fertilizer containing flavonoid nutrient signaling substances is obtained.

[0073] Test case

[0074] 1. Test method:

[0075] To investigate the effect of the controlled-release nitrogen fertilizer containing flavonoid nutrient signaling substances specifically for maize prepared in this invention on maize yield, a pot experiment was conducted at Shandong Agricultural University. The maize variety used was "Zhengdan 958," with one maize plant per pot. Specific experimental treatments are as follows:

[0076] Treatment of PK (no nitrogen application): Apply 6.5g of diammonium phosphate and 4.5g of potassium sulfate;

[0077] Treatment of NPK (conventional nitrogen, phosphorus, and potassium fertilization): Apply 6.8g of urea, 4.5g of diammonium phosphate, and 4.5g of potassium sulfate;

[0078] Treatment MA1: Apply 6.8g of the controlled-release nitrogen fertilizer prepared in Example 1, 4.5g of diammonium phosphate, and 4.5g of potassium sulfate;

[0079] Treatment of MA2: Apply 6.8g of the controlled-release nitrogen fertilizer prepared in Example 2, 4.5g of diammonium phosphate, and 4.5g of potassium sulfate;

[0080] Treatment of MA3: Apply 6.8g of the controlled-release nitrogen fertilizer prepared in Example 3, 4.5g of diammonium phosphate, and 4.5g of potassium sulfate;

[0081] Treatment of MA4: Apply 6.8g of the controlled-release nitrogen fertilizer prepared in Example 4, 4.5g of diammonium phosphate, and 4.5g of potassium sulfate;

[0082] Treatment MA5: Apply 6.8g of the controlled-release nitrogen fertilizer prepared in Example 5, 4.5g of diammonium phosphate, and 4.5g of potassium sulfate;

[0083] Treatment of MA6: Apply 6.8g of the controlled-release nitrogen fertilizer prepared in Example 6, 4.5g of diammonium phosphate, and 4.5g of potassium sulfate;

[0084] Treatment MA7: application of controlled-release nitrogen fertilizer prepared in Example 7 6.8 g, diammonium phosphate 4.5 g, potassium sulfate 4.5 g;

[0085] Treatment CK1: application of controlled-release nitrogen fertilizer prepared in Comparative Example 1 6.8 g, diammonium phosphate 4.5 g, potassium sulfate 4.5 g.

[0086] Treatment CK2: application of controlled-release nitrogen fertilizer prepared in Comparative Example 2 6.8 g, diammonium phosphate 4.5 g, potassium sulfate 4.5 g.

[0087] Treatment CK3: application of controlled-release nitrogen fertilizer prepared in Comparative Example 3 6.8 g, diammonium phosphate 4.5 g, potassium sulfate 4.5 g.

[0088] In each of the above treatments, the fertilizer was applied in 20 kg of soil per pot, and the phosphorus and potassium fertilizers in each treatment were uniformly mixed into the 20 kg of soil, and the nitrogen fertilizer was applied into the soil by seed and fertilizer co-seeding. The soil composition of each treatment was kept consistent, and each treatment was repeated four times. The corn was harvested after 96 days of growth, and the grain yield was calculated as the corn yield based on a moisture content of 14%.

[0089] The total nitrogen and nitrogen uptake of the corn plants in each of the above treatments were determined. The specific determination method was as follows: the aboveground plant samples of corn were dried and ground, and then subjected to H2SO4-H2O2 combined digestion in a digestion furnace. The ammonium nitrogen concentration in the digestion solution was determined by Kjeldahl determination, and the total nitrogen and nitrogen uptake of the plants were calculated.

[0090] The nitrogen utilization rate of each of the above treatments was determined. The specific determination method was as follows: the total nitrogen content of the plants was determined by concentrated sulfuric acid-hydrogen peroxide combined digestion Kjeldahl determination, and the nitrogen uptake of corn = corn biomass * total nitrogen content of plants. Nitrogen utilization rate (%) = (nitrogen uptake of corn in nitrogen application treatment - nitrogen uptake of corn in PK treatment) / nitrogen application amount x 100.

[0091] The relative abundance of each of the above treatments was determined by 16S rRNA high-throughput sequencing technology. Paenibacillus triticisoli

[0092] 2. Test results:

[0093] (1) Corn yield:

[0094] The statistical results of the corn yield of each treatment are shown in Table 1. Figure 1 ​The results show that the controlled release urea prepared by Example 1 can improve the yield of corn, and compared with the treatment without nitrogen, the yield of corn is increased by 25.39%; compared with the NPK treatment, the yield of corn is increased by 5.72%. The controlled release urea prepared by Example 2 can improve the yield of corn, and compared with the treatment without nitrogen, the yield of corn is increased by 29.07%; compared with the NPK treatment, the yield of corn is increased by 8.82%. The controlled release urea prepared by Example 3 can improve the yield of corn, and compared with the treatment without nitrogen, the yield of corn is increased by 26.94%; compared with the NPK treatment, the yield of corn is increased by 7.03%. The controlled release urea prepared by Example 4 can improve the yield of corn, and compared with the treatment without nitrogen, the yield of corn is increased by 32.75%; compared with the NPK treatment, the yield of corn is increased by 11.93%. The controlled release urea prepared by Example 5 can improve the yield of corn, and compared with the treatment without nitrogen, the yield of corn is increased by 31.20%; compared with the NPK treatment, the yield of corn is increased by 10.62%. The controlled release urea prepared by Example 6 can improve the yield of corn, and compared with the treatment without nitrogen, the yield of corn is increased by 30.23%; compared with the NPK treatment, the yield of corn is increased by 9.80%. The controlled release urea prepared by Example 7 can improve the yield of corn, and compared with the treatment without nitrogen, the yield of corn is increased by 33.72%; compared with the NPK treatment, the yield of corn is increased by 12.75%. Compared with CK1, MA7 is increased by 6.81%; compared with CK2, MA7 is increased by 5.99%, and compared with CK3, MA7 is increased by 4.70%.

[0095] The yield of Examples 1-7 is higher than that of the comparative examples

[0096] (2) Total nitrogen and nitrogen absorption of corn plants:

[0097] The statistical results of total nitrogen and nitrogen absorption of corn plants in each treatment are shown in Table 2. Figure 2 The results show that the controlled release urea prepared by Example 1 can improve the total nitrogen and nitrogen absorption of corn plants, and compared with the treatment without nitrogen, the total nitrogen and nitrogen absorption of corn plants are increased by 47.98% and 56.41% respectively; compared with the NPK treatment, they are increased by 14.30% and 29.79% respectively.

[0098] The controlled release urea prepared by Example 2 can improve the total nitrogen and nitrogen absorption of plants, and compared with the treatment without nitrogen, the total nitrogen and nitrogen absorption of plants are increased by 48.51% and 62.18% respectively; compared with the NPK treatment, they are increased by 14.72% and 34.57% respectively.

[0099] The controlled release urea prepared in Example 3 can improve the total nitrogen and nitrogen absorption of the plants. Compared with the treatment without nitrogen, the total nitrogen and nitrogen absorption of the plants are increased by 46.58% and 61.54% respectively; compared with the NPK treatment, the total nitrogen and nitrogen absorption of the plants are increased by 13.22% and 34.04% respectively.

[0100] The controlled release urea prepared in Example 4 can improve the total nitrogen and nitrogen absorption of the plants. Compared with the treatment without nitrogen, the total nitrogen and nitrogen absorption of the plants are increased by 50.27% and 57.05% respectively; compared with the NPK treatment, the total nitrogen and nitrogen absorption of the plants are increased by 16.07% and 30.32% respectively.

[0101] The controlled release urea prepared in Example 5 can improve the total nitrogen and nitrogen absorption of the plants. Compared with the treatment without nitrogen, the total nitrogen and nitrogen absorption of the plants are increased by 49.42% and 60.90% respectively; compared with the NPK treatment, the total nitrogen and nitrogen absorption of the plants are increased by 15.42% and 33.51% respectively.

[0102] The controlled release urea prepared in Example 6 can improve the total nitrogen and nitrogen absorption of the plants. Compared with the treatment without nitrogen, the total nitrogen and nitrogen absorption of the plants are increased by 47.66% and 69.87% respectively; compared with the NPK treatment, the total nitrogen and nitrogen absorption of the plants are increased by 14.06% and 40.96% respectively.

[0103] The controlled release urea prepared in Example 7 can improve the total nitrogen and nitrogen absorption of the plants. Compared with the treatment without nitrogen, the total nitrogen and nitrogen absorption of the plants are increased by 52.57% and 73.72% respectively; compared with the NPK treatment, the total nitrogen and nitrogen absorption of the plants are increased by 17.85% and 44.15% respectively, compared with CK1, the total nitrogen and nitrogen absorption of the plants are increased by 17.13% and 26.05% respectively, compared with CK2, the total nitrogen and nitrogen absorption of the plants are increased by 12.12% and 18.86% respectively, compared with CK3, the total nitrogen and nitrogen absorption of the plants are increased by 10.38% and 17.83% respectively.

[0104] (3) Nitrogen utilization rate:

[0105] The nitrogen utilization rate of each treatment is shown in Table 6. Figure 3 Compared with the NPK treatment, the nitrogen utilization rate of MA1 treatment is increased by 5.6 percentage points, the nitrogen utilization rate of MA2 treatment is increased by 6 percentage points, the nitrogen utilization rate of MA3 treatment is increased by 5.8 percentage points, the nitrogen utilization rate of MA4 treatment is increased by 8.3 percentage points, the nitrogen utilization rate of MA5 treatment is increased by 7.5 percentage points, the nitrogen utilization rate of MA6 treatment is increased by 8.0 percentage points, the nitrogen utilization rate of M7 treatment is increased by 7.6 percentage points, the nitrogen utilization rate of MA7 treatment is increased by 12.5 percentage points, the nitrogen utilization rate of CK1 treatment is increased by 3.8 percentage points, the nitrogen utilization rate of CK2 treatment is increased by 4.1 percentage points, and the nitrogen utilization rate of CK3 treatment is increased by 4.5 percentage points.

[0106] (4) Paenibacillus triticisoli Relative abundance of the following:

[0107] The composition and characteristics of the bacterial community in the rhizosphere of corn under different treatments were significantly different. The PCA results showed that the first and second principal components explained 60% of the variance. At the genus level, the bacterial community composition of the treatment with added signal substances was significantly separated from the PK and NPK treatments. At the genus level, Paenibacillus triticisoli had the highest relative abundance, followed by Comamonadaceae , Sphingomonadaceae and Xanthomonadaceae . Compared with the treatment MA7 Paenibacillus triticisoli , the relative abundance of the treatment MA1 Oxalobacteraceae was the highest. At the ASV level, the relative abundance of ASV was significantly affected by signal substances and nitrogen content. Signal substances significantly enriched 3 ASVs belonging to

[0108] The relative abundance of the following: Paenibacillus triticisoli of each treatment was determined as shown in Figure 4 . The application of flavonoid components in the component can greatly increase the relative abundance of Paenibacillus triticisoli . Compared with the NPK treatment, the relative abundance of Paenibacillus triticisoli in the MA1 treatment increased by 2.45 percentage points, the relative abundance of Paenibacillus triticisoli in the MA2 treatment increased by 2.25 percentage points, the relative abundance of Paenibacillus triticisoli in the MA3 treatment increased by 3 percentage points, the relative abundance of Paenibacillus triticisoli in the MA4 treatment increased by 4.75 percentage points, the relative abundance of Paenibacillus triticisoli in the MA5 treatment increased by 5.5 percentage points, the relative abundance of Paenibacillus triticisoli in the MA6 treatment increased by 6.8 percentage points, and the relative abundance of Paenibacillus triticisoli in the MA7 treatment increased by 10.0 percentage points. The relative abundance of Paenibacillus triticisoli in the CK1 treatment increased by 3.8 percentage points, the relative abundance of Paenibacillus triticisoli in the CK2 treatment increased by 4.66 percentage points, and the relative abundance of Paenibacillus triticisoli in the CK3 treatment increased by 4.11 percentage points. This shows that the signal substance-containing controlled-release nitrogen fertilizer of the application is beneficial to strengthening the mutualistic symbiotic relationship between corn and nitrogen-fixing microorganisms and promoting the acquisition of soil nitrogen by corn.

[0109] At different growth stages of corn, destructive sampling was performed on the rhizosphere soil, and the content of flavonoid nutrient signal substances released from the corn-specific controlled-release urea in the rhizosphere soil was determined by liquid chromatography-mass spectrometry (LC-MS) technology. The results are shown in Figure 5 .

[0110] In summary, in the controlled-release nitrogen fertilizer of the present application, the addition of the flavonoid component as a signal substance can improve the nitrogen utilization rate and Paenibacillus triticisoli the nitrogen fixation capacity, thereby improving the yield of corn, further improving the effect of nitrogen fertilizer, and having a significant synergistic effect.

[0111] Test Example 2

[0112] The nitrogen release rate of the controlled-release urea prepared in Example 7 and Comparative Examples 1-3 was determined by the 25℃ static water extraction Kjeldahl nitrogen method (Reference: Yanxiao, Zhangmin, Weizongqiang, et al. Nutrient rapid determination of controlled-release urea and nitrogen release rate in field soil. Journal of Soil and Water Conservation, 2010, 24(1): 167-171).

[0113] As shown in Figure 5 , the release of the flavonoid nutrient signal substance of Example 7 is highly synergistic with the nitrogen release of the corn-specific controlled-release nitrogen fertilizer. The results are shown in Figure 6 , within 30 days after the corn emergence, the nitrogen release of the controlled-release nitrogen fertilizer of Example 7 is faster, at this time (pre-growth period) the corn is more sensitive to nitrogen, and the release of fertilizer nitrogen helps to meet the demand of the corn nitrogen sensitive period. When the corn grows to 40-50 days, the release rate of the fertilizer is significantly accelerated, the nutrient release of Comparative Example 1 is almost complete, and the nutrient release rate of Comparative Examples 2-3 is also higher than that of Example 7. The controlled-release nitrogen fertilizer of Example 7 has a longer release period, which is more than 40 days, the release within 25 days before the corn growth is not less than 30% of the total nutrient, the release within 60 days is not less than 65% of the total nutrient, and the release within 80 days is not less than 80% of the total nutrient, which is beneficial to the growth of the corn at the jointing stage and the formation of the yield at the later stage.

[0114] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A controlled-release nitrogen fertilizer for corn containing flavonoid nutrient signaling substances, characterized in that, Raw materials including the following weight fractions: 1000 parts nitrogen fertilizer, 5-10 parts flavonoid nutrient signaling substance microcapsules, and 50-100 parts coating material; The flavonoid nutrient signaling substance microcapsules were prepared by the following method: (1) Dissolve flavonoid nutrient signaling substances and benzoic acid in deionized water, adjust the pH to alkaline with alkaline solution to obtain signaling substance solution, dissolve polylactic acid-glycolic acid copolymer in dichloromethane to obtain PLGA solution, slowly pour PLGA solution into signaling substance solution, homogenize and emulsify, and then stir to obtain water / oil type emulsion. The flavonoid nutrient signaling substances are selected from at least one of naringenin, rutin, and apigenin; (2) Polyvinyl alcohol is dissolved in deionized water to obtain a polyvinyl alcohol solution. Under constant temperature water bath, the polyvinyl alcohol solution is added to the water / oil type emulsion, homogenized and emulsified, and then stirred to obtain a water / oil / water type emulsion. (3) The water / oil / water emulsion was frozen and centrifuged under stirring to obtain a precipitate, which was then washed and freeze-dried to obtain flavonoid nutrient signaling microcapsules; The coating material is obtained by mixing vegetable oil, isocyanate, and sodium carboxymethyl cellulose in a mass ratio of 6:5:

5.

2. The controlled-release nitrogen fertilizer for corn containing flavonoid nutrient signaling substances according to claim 1, characterized in that, In step (1), the mass ratio of the flavonoid nutrient signaling substance to benzoic acid is 3:1; the pH is adjusted to 11; the mass concentration of polylactic acid-glycolic acid copolymer in the PLGA solution is 1%; the volume ratio of the signaling substance solution to the PLGA solution is 1:3; the homogenization speed is 10000 rpm; the emulsification time is 5 min; and the stirring speed is 500 rpm for 1 h.

3. The controlled-release nitrogen fertilizer for corn containing flavonoid nutrient signaling substances according to claim 1, characterized in that, In step (2), the concentration of the polyvinyl alcohol solution is 10 g / L; the temperature of the constant temperature water bath is 95°C; the volume ratio of the polyvinyl alcohol solution to the water / oil emulsion is 2.5:1; the homogenization speed is 10,000 rpm; the emulsification time is 5 min; and the stirring speed is 400 rpm for 10 h.

4. The controlled-release nitrogen fertilizer for corn containing flavonoid nutrient signaling substances according to claim 1, characterized in that, In step (3), the stirring speed is 10,000 rpm; the temperature of the freeze centrifugation is -20℃; and the freeze drying is freeze drying at -80℃ for 10 h.

5. The controlled-release nitrogen fertilizer for corn containing flavonoid nutrient signaling substances according to claim 1, characterized in that, The controlled-release nitrogen fertilizer containing flavonoid nutrient signaling substances specifically for corn is prepared by the following method: The nitrogen fertilizer is preheated, and microcapsules of flavonoid nutrient signaling substances are added to the coating material and mixed evenly. The mixture is then sprayed onto the surface of the nitrogen fertilizer in multiple applications. After curing, a controlled-release nitrogen fertilizer containing flavonoid nutrient signaling substances for corn is obtained.

6. The controlled-release nitrogen fertilizer for corn containing flavonoid nutrient signaling substances according to claim 5, characterized in that, The preheating temperature is 75℃ and the time is 30 minutes; the number of spraying times is ≥2.

7. The controlled-release nitrogen fertilizer for corn containing flavonoid nutrient signaling substances according to claim 5, characterized in that, The preheating hot air flow rate is 380 m³ / h. 3 The spraying speed is 5 g / min; the curing time is 10 min.

8. The controlled-release nitrogen fertilizer containing flavonoid nutrient signaling substances specifically for corn, as described in any one of claims 1 to 7, is used in at least one of the following: 1) to 4): 1) Increase corn yield; 2) Increase the total nitrogen and nitrogen uptake of corn plants; 3) Improve nitrogen fertilizer utilization rate; 4) Improve the rhizosphere of maize Paenibacillus triticisoli The relative abundance of.

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