Brown algae oligosaccharide, preparation method thereof and water-soluble fertilizer

Abstract

The present invention provides a brown algae oligosaccharide, a preparation method thereof and a water-soluble fertilizer, and belongs to the technical field of fertilizer manufacturing. The preparation method of the brown algae oligosaccharide of the present invention comprises: crushing the brown algae, adding a composite enzymatic hydrolysis solution for enzymolysis, filtering, mixing the filtrate with an ethanol solution for alcohol precipitation, centrifuging, and precipitating into crude brown algae polysaccharide; adding an acid solution to the crude brown algae polysaccharide for acid hydrolysis, adjusting the pH value to neutral, centrifuging, and decompressing and concentrating the supernatant to obtain the brown algae oligosaccharide. The present invention adopts a composite method of enzymolysis, alcohol precipitation and acid hydrolysis to extract brown algae oligosaccharide, with a short extraction time and a high brown algae oligosaccharide output rate; the brown algae oligosaccharide prepared by the present invention can protect fertilizer inhibitors and increase the action time of the inhibitors; the brown algae oligosaccharide prepared by the present invention is added to water-soluble fertilizers to quickly improve the adaptability of plants to adversity, improve crop quality, and increase crop yield.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizer manufacturing, and in particular relates to brown algae oligosaccharide, a preparation method thereof, and a water-soluble fertilizer. Background Art

[0002] Seaweed fertilizer is a new type of fertilizer containing algae-derived biostimulants. It not only improves soil but also promotes crop growth, increases crop yields, and enhances crop resistance to adverse environmental conditions. It has broad application prospects in the context of reducing the use of chemical fertilizers and increasing their efficiency. Seaweed polysaccharides are a key component of algae-derived biostimulants, accounting for over 20% of the dry weight of brown seaweed. Field trials have shown that exogenous application of seaweed polysaccharides can improve crop stress resistance indicators such as proline and antioxidant dismutase. However, seaweed polysaccharide molecules are relatively large, making them difficult for plants to absorb and utilize efficiently. Therefore, further degradation of seaweed polysaccharides to produce highly soluble, small molecular weight seaweed oligosaccharides is more conducive to absorption and utilization by plant roots.

[0003] Compared with traditional fertilizers, water-soluble fertilizers provide the nutrients needed by plants in the form of solutions. Plants can absorb and utilize these nutrients faster and more efficiently. Applying seaweed oligosaccharides to water-soluble fertilizers can be absorbed by plants faster, thereby quickly improving the plant's resistance to adverse stress and maintaining normal crop growth.

[0004] At present, the market price of high-purity brown seaweed oligosaccharides is high, which seriously affects their application in fertilizers. Therefore, how to improve the production process, increase the output rate of brown seaweed oligosaccharides, and reduce production costs will become a bottleneck for the industrial application of brown seaweed oligosaccharides in fertilizers. The processes for preparing seaweed oligosaccharides by degrading seaweed polysaccharides are mainly divided into physical methods, chemical methods, and enzymatic methods. Among them, the physical method is easy to operate and pollution-free, but the degradation efficiency is low, the reaction mechanism is unclear, and the reproducibility is not high; the chemical method has a rapid reaction, high efficiency, and low cost, but it is easy to produce by-products; the enzymatic method has strong specificity and a high output rate of brown seaweed oligosaccharides, but the reaction speed is slow and the efficiency is low. Therefore, it is urgent to invent a preparation method for brown seaweed oligosaccharides with a short extraction time and high output rate. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for preparing brown algae oligosaccharides, which can extract brown algae oligosaccharides in a short time and with a high output rate.

[0006] The present invention also provides a brown algae oligosaccharide, which can protect fertilizer inhibitors and increase the action time of the inhibitors.

[0007] The present invention also provides a water-soluble fertilizer containing brown algae oligosaccharides, which can quickly improve the adaptability of plants to adverse conditions, improve crop quality, and increase crop yield.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The invention provides a method for preparing brown algae oligosaccharides, comprising: crushing brown algae, adding a composite enzymatic hydrolysis solution for enzymatic hydrolysis, filtering, mixing the filtrate with an ethanol solution, performing alcohol precipitation, centrifuging, and precipitating to obtain crude brown algae polysaccharides; adding an acid solution to the crude brown algae polysaccharides for acid hydrolysis, adjusting the pH value to neutral, centrifuging, and concentrating the supernatant under reduced pressure to obtain the brown algae oligosaccharides; the composite enzymatic hydrolysis solution is composed of the following raw materials in percentage by weight: 1% to 3% of cellulase, 1% to 3% of pectinase, 1% to 3% of xylanase, and 1% to 3% of α-amylase.

[0010] Preferably, the material-liquid ratio of the enzymatic hydrolysis is 1:18-20 g / ml, the temperature is 37-40° C., the pH value is 7-8, and the time is 4-6 h.

[0011] Preferably, the volume fraction of the ethanol solution is 75% to 85%, and the volume ratio of the filtrate to the ethanol solution is 1:1 to 1.2.

[0012] Preferably, the acid solution is a sulfuric acid solution with a mass concentration of 3% to 5%; the material-liquid ratio of the crude fucoidan to the acid solution is 1:50 to 60 g / ml; the acid hydrolysis temperature is 95 to 105° C., and the time is 3 to 4 hours.

[0013] Preferably, the temperature of the reduced pressure concentration is 65-75°C.

[0014] The present invention also provides brown algae oligosaccharide obtained by the above preparation method.

[0015] The present invention also provides a water-soluble fertilizer containing the above-mentioned brown algae oligosaccharide, comprising the following raw materials in parts by weight: 500-600 parts of desalted water, 230-260 parts of urea, 180-220 parts of monoammonium phosphate, 230-260 parts of potassium sulfate, 50-60 parts of chelated trace elements, 8-13 parts of the above-mentioned brown algae oligosaccharide and 8-13 parts of compound fertilizer inhibitor.

[0016] Preferably, the chelated trace elements are composed of EDTA-Fe, EDTA-Mn, EDTA-Zn, EDTA-Cu, EDTA-Mo and EDTA-B in a weight ratio of 8-13:8-13:8-13:1-3:0.5-1.5:0.3-0.8.

[0017] Preferably, the compound fertilizer inhibitor is composed of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 0.5-1.5:0.5-1.5.

[0018] The present invention also provides a method for preparing the water-soluble fertilizer, comprising: mixing urea, monoammonium phosphate, potassium sulfate, chelated trace elements, the brown algae oligosaccharide and desalted water, heating and stirring until dissolved, and adding a compound fertilizer inhibitor after cooling to obtain the water-soluble fertilizer.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention provides a method for preparing brown algae oligosaccharides, comprising: crushing brown algae, adding a composite enzymatic hydrolysis solution for enzymatic hydrolysis, filtering, mixing the filtrate with an ethanol solution for alcohol precipitation, centrifuging, and precipitating crude brown algae polysaccharides; adding an acid solution to the crude brown algae polysaccharides for acid hydrolysis, adjusting the pH value to neutral, centrifuging, and concentrating the supernatant under reduced pressure to obtain the brown algae oligosaccharides. The method for preparing brown algae oligosaccharides of the present invention adopts a composite method of enzymatic hydrolysis, alcohol precipitation, and acid hydrolysis. First, the composite enzymatic hydrolysis is used to break the seaweed cell wall to promote the dissolution of brown algae polysaccharides, then the brown algae polysaccharides are separated by alcohol precipitation, and then the crude seaweed polysaccharides are further decomposed by sulfuric acid. The method has a short extraction time and a high brown algae oligosaccharide yield. The brown algae oligosaccharides prepared by the present invention can protect fertilizer inhibitors and increase the inhibitor's action time. The brown algae oligosaccharides prepared by the present invention can be added to water-soluble fertilizers to quickly improve the adaptability of plants to adverse conditions, improve crop quality, and increase crop yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the preparation method of brown algae oligosaccharides. DETAILED DESCRIPTION

[0022] The invention provides a method for preparing brown algae oligosaccharides, comprising: crushing brown algae, adding a composite enzymatic hydrolysis solution for enzymatic hydrolysis, filtering, mixing the filtrate with an ethanol solution, performing alcohol precipitation, centrifuging, and precipitating to obtain crude brown algae polysaccharides; adding an acid solution to the crude brown algae polysaccharides for acid hydrolysis, adjusting the pH value to neutral, centrifuging, and concentrating the supernatant under reduced pressure to obtain the brown algae oligosaccharides; the composite enzymatic hydrolysis solution is composed of the following raw materials in percentage by weight: 1% to 3% of cellulase, 1% to 3% of pectinase, 1% to 3% of xylanase, and 1% to 3% of α-amylase.

[0023] In the present invention, the brown algae is preferably Sargassum, Ascophyllum nodosum, Laminaria japonica, Undaria pinnatifida or Macroalgae, more preferably Sargassum.

[0024] The present invention also preferably includes the steps of washing the brown algae, removing impurities and surface salts, and drying before the pulverization.

[0025] The material-liquid ratio of the enzymatic hydrolysis of the present invention is preferably 1:18-20 g / ml, more preferably 1:19 g / ml, the temperature is preferably 37-40°C, more preferably 38°C, the pH is preferably 7-8, more preferably 7.5, and the time is preferably 4-6 hours, more preferably 5 hours. The cell wall of brown algae cells is divided into an alginic layer and a fibrous layer. Enzymatic hydrolysis of brown algae by a composite enzymatic hydrolysis solution composed of cellulase, pectinase, xylanase and α-amylase can effectively break down the brown algae cell wall and promote the dissolution of brown algae polysaccharides.

[0026] The volume fraction of the ethanol solution of the present invention is preferably 75% to 85%, more preferably 80%, and the volume ratio of the filtrate to the ethanol solution is preferably 1:1 to 1.2, more preferably 1:1.1. The fucoidan is further separated by alcohol precipitation.

[0027] The centrifugal speed of the present invention is preferably 7500-8500 rpm / min, more preferably 8000 rpm / min, and the time is preferably 3-8 min, more preferably 5 min.

[0028] The acid solution of the present invention is preferably a sulfuric acid solution with a mass concentration of 3% to 5%, more preferably a 4% sulfuric acid solution; the material-to-liquid ratio of the crude fucoidan to the acid solution is preferably 1:50 to 60 g / ml, more preferably 1:55 g / ml; the acid hydrolysis temperature is preferably 95 to 105°C, more preferably 100°C, and the time is preferably 3 to 4 hours, more preferably 3.5 hours. Further decomposition of the crude fucoidan with sulfuric acid under high temperature conditions yields seaweed oligosaccharides with a low degree of polymerization.

[0029] The temperature of the reduced pressure concentration according to the present invention is preferably 65-75°C, more preferably 70°C.

[0030] The present invention also provides brown algae oligosaccharide obtained by the above preparation method.

[0031] The present invention also provides a water-soluble fertilizer containing the above-mentioned brown algae oligosaccharide, comprising the following raw materials in parts by weight: 500-600 parts of desalted water, 230-260 parts of urea, 180-220 parts of monoammonium phosphate, 230-260 parts of potassium sulfate, 50-60 parts of chelated trace elements, 8-13 parts of the above-mentioned brown algae oligosaccharide and 8-13 parts of compound fertilizer inhibitor.

[0032] The chelated trace elements of the present invention are preferably composed of EDTA-Fe, EDTA-Mn, EDTA-Zn, EDTA-Cu, EDTA-Mo and EDTA-B in a weight ratio of 8-13:8-13:8-13:1-3:0.5-1.5:0.3-0.8, more preferably 10:10:10:2:1:0.5.

[0033] The compound fertilizer inhibitor of the present invention is preferably composed of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 0.5-1.5:0.5-1.5, more preferably 1:1.

[0034] The present invention also provides a method for preparing the water-soluble fertilizer, comprising: mixing urea, monoammonium phosphate, potassium sulfate, chelated trace elements, the brown algae oligosaccharide and desalted water, heating and stirring until dissolved, and adding a compound fertilizer inhibitor after cooling to obtain the water-soluble fertilizer.

[0035] The temperature of the heating and stirring in the present invention is preferably not higher than 90°C.

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In the following examples, unless otherwise specified, all methods are conventional.

[0038] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0039] Example 1

[0040] 1. Preparation method of brown algae oligosaccharide

[0041] (1) Wash fresh Sargassum to remove impurities and surface salt, dry and grind into powder;

[0042] (2) 50 g of Sargassum powder was added to a composite enzymatic hydrolysate consisting of 2% cellulase, 2% pectinase, 2% xylanase, and 2% α-amylase, with a material-liquid mass ratio of 1:19 g / ml, an enzymatic hydrolysis temperature of 37 °C, an enzymatic hydrolysis pH of 7, and an enzymatic hydrolysis time of 4 h;

[0043] (3) Filter the enzymatic hydrolyzate to remove the residue, add 80% ethanol solution to the filtrate for alcohol precipitation, and centrifuge at 8000 rpm / min for 5 minutes after precipitation to obtain crude fucoidan;

[0044] (4) Add 4% sulfuric acid solution to the crude fucoidan, with the material-liquid ratio of crude fucoidan to acid solution being 1:50 g / ml. Mix the solution thoroughly and heat to 100°C. Acid hydrolysis is performed for 3 h.

[0045] (5) adjusting the pH of the acid hydrolyzate to neutral with ammonia water to obtain a brown algal oligosaccharide solution;

[0046] (6) The brown algae oligosaccharide solution was concentrated under reduced pressure at 70°C to obtain brown algae oligosaccharide.

[0047] 2. Water-soluble fertilizer containing brown algae oligosaccharides

[0048] (1) Add 250 parts of urea, 200 parts of monoammonium phosphate, 250 parts of potassium sulfate, 55 parts of chelated trace elements, and 10 parts of brown algae oligosaccharide to 500 parts of deionized water, and heat and stir to promote dissolution;

[0049] (2) After the solution is cooled, 10 parts of a compound fertilizer inhibitor is added, stirred evenly, and filtered to obtain a water-soluble fertilizer containing brown algae oligosaccharides.

[0050] The weight ratio of the chelated trace elements is: EDTA-Fe: EDTA-Mn: EDTA-Zn: EDTA-Cu: EDTA-Mo: EDTA-B = 10:10:10:2:1:0.5;

[0051] The compound fertilizer inhibitor consists of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 1:1.

[0052] Example 2

[0053] 1. Preparation method of brown algae oligosaccharide

[0054] (1) Wash fresh Sargassum to remove impurities and surface salt, dry and grind into powder;

[0055] (2) 50 g of brown algae powder was added to a composite enzymatic hydrolysis solution consisting of 2% cellulase, 2% pectinase, 2% xylanase, and 2% α-amylase, with a material-liquid ratio of 1:20 g / ml, an enzymatic hydrolysis temperature of 40°C, an enzymatic hydrolysis pH of 8, and an enzymatic hydrolysis time of 6 h;

[0056] (3) Filter the enzymatic hydrolyzate to remove the residue, add 80% ethanol solution to the filtrate for alcohol precipitation, and centrifuge at 8000 rpm / min for 5 minutes after precipitation to obtain crude fucoidan;

[0057] (4) Add 4% sulfuric acid solution to the crude fucoidan, with the material-liquid ratio of crude fucoidan to acid solution being 1:60 g / ml. Mix the solution and heat it to 100°C. Acid hydrolysis time is 4 h.

[0058] (5) adjusting the pH of the acid hydrolyzate to neutral with ammonia water to obtain a brown algal oligosaccharide solution;

[0059] (6) The brown algae oligosaccharide solution was concentrated under reduced pressure at 70°C to obtain brown algae oligosaccharide.

[0060] 2. Water-soluble fertilizer containing brown algae oligosaccharides

[0061] (1) Add 250 parts of urea, 200 parts of monoammonium phosphate, 250 parts of potassium sulfate, 55 parts of chelated trace elements, and 10 parts of brown algae oligosaccharide to 550 parts of deionized water, and heat and stir to promote dissolution;

[0062] (2) After the solution is cooled, 10 parts of a compound fertilizer inhibitor is added, stirred evenly, and filtered to obtain a water-soluble fertilizer containing brown algae oligosaccharides.

[0063] The weight ratio of the chelated trace elements is: EDTA-Fe: EDTA-Mn: EDTA-Zn: EDTA-Cu: EDTA-Mo: EDTA-B = 10:10:10:2:1:0.5;

[0064] The compound fertilizer inhibitor consists of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 1:1.

[0065] Example 3

[0066] 1. Preparation method of brown algae oligosaccharide

[0067] (1) Wash fresh Sargassum to remove impurities and surface salt, dry and grind into powder;

[0068] (2) 50 g of brown algae powder was added to a composite enzymatic hydrolysis solution consisting of 2% cellulase, 2% pectinase, 2% xylanase, and 2% α-amylase, with a material-liquid ratio of 1:19 g / ml, an enzymatic hydrolysis temperature of 38°C, an enzymatic hydrolysis pH of 7, and an enzymatic hydrolysis time of 5 h;

[0069] (3) Filter the enzymatic hydrolyzate to remove the residue, add 80% ethanol solution to the filtrate for alcohol precipitation, and centrifuge at 8000 rpm / min for 5 minutes after precipitation to obtain crude fucoidan;

[0070] (4) Add 4% sulfuric acid solution to the crude fucoidan, with the material-liquid ratio of crude fucoidan to acid solution being 1:55 g / ml. Mix the solution and heat it to 100°C. The acid hydrolysis time is 3.5 h.

[0071] (5) adjusting the pH of the acid hydrolyzate to neutral with ammonia water to obtain a brown algal oligosaccharide solution;

[0072] (6) The brown algae oligosaccharide solution was concentrated under reduced pressure at 70°C to obtain brown algae oligosaccharide.

[0073] 2. Water-soluble fertilizer containing brown algae oligosaccharides

[0074] (1) Add 250 parts of urea, 200 parts of monoammonium phosphate, 250 parts of potassium sulfate, 55 parts of chelated trace elements, and 10 parts of brown algae oligosaccharide to 600 parts of deionized water, and heat and stir to promote dissolution;

[0075] (2) After the solution is cooled, 10 parts of a compound fertilizer inhibitor is added, stirred evenly, and filtered to obtain a water-soluble fertilizer containing brown algae oligosaccharides.

[0076] The weight ratio of the chelated trace elements is: EDTA-Fe: EDTA-Mn: EDTA-Zn: EDTA-Cu: EDTA-Mo: EDTA-B = 10:10:10:2:1:0.5;

[0077] The compound fertilizer inhibitor consists of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 1:1.

[0078] Comparative Example 1

[0079] 1. Preparation of brown algal oligosaccharides

[0080] (1) Wash fresh Sargassum to remove impurities and surface salt, dry and grind into powder;

[0081] (2) 50 g of brown algae powder was added to a composite enzymatic hydrolysis solution consisting of 2% cellulase, 2% pectinase, 2% xylanase, and 2% α-amylase, with a material-liquid ratio of 1:19 g / ml, an enzymatic hydrolysis temperature of 38°C, an enzymatic hydrolysis pH of 7, and an enzymatic hydrolysis time of 5 h;

[0082] (3) The enzymatic hydrolyzate was filtered to remove the residue, and 80% ethanol solution was added to the filtrate for alcohol precipitation. After precipitation, the solution was centrifuged at 8000 rpm / min for 5 minutes to obtain a crude extract containing brown algal oligosaccharides.

[0083] 2. Water-soluble fertilizer containing brown algae oligosaccharides

[0084] (1) Add 250 parts of urea, 200 parts of monoammonium phosphate, 250 parts of potassium sulfate, 55 parts of chelated trace elements, and 10 parts of the above crude extract to 500 parts of deionized water, and heat and stir to promote dissolution;

[0085] (2) After the solution is cooled, 10 parts of a compound fertilizer inhibitor is added, stirred evenly, and filtered to obtain a water-soluble fertilizer containing brown algae oligosaccharides.

[0086] The weight ratio of the chelated trace elements is: EDTA-Fe: EDTA-Mn: EDTA-Zn: EDTA-Cu: EDTA-Mo: EDTA-B = 10:10:10:2:1:0.5;

[0087] The compound fertilizer inhibitor consists of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 1:1.

[0088] Comparative Example 2

[0089] 1. Preparation method of brown algae oligosaccharide

[0090] (1) Wash fresh Sargassum to remove impurities and surface salt, dry and grind into powder;

[0091] (2) 50 g of Sargassum powder was added to a composite enzymatic hydrolysis solution consisting of 2% cellulase and 2% pectinase, with a material-liquid mass ratio of 1:19 g / ml, an enzymatic hydrolysis temperature of 37 °C, an enzymatic hydrolysis pH of 7, and an enzymatic hydrolysis time of 4 h;

[0092] (3) Filter the enzymatic hydrolyzate to remove the residue, add 80% ethanol solution to the filtrate for alcohol precipitation, and centrifuge at 8000 rpm / min for 5 minutes after precipitation to obtain crude fucoidan;

[0093] (4) Add 4% sulfuric acid solution to the crude fucoidan, with the material-liquid ratio of crude fucoidan to acid solution being 1:50. After the solution is mixed, heat it to 100°C and acid hydrolyze it for 3 hours.

[0094] (5) adjusting the pH of the acid hydrolyzate to neutral with ammonia water to obtain a brown algal oligosaccharide solution;

[0095] (6) The brown algae oligosaccharide solution was concentrated under reduced pressure at 70°C to obtain brown algae oligosaccharide.

[0096] 2. Water-soluble fertilizer containing brown algae oligosaccharides

[0097] (1) Add 250 parts of urea, 200 parts of monoammonium phosphate, 250 parts of potassium sulfate, 55 parts of chelated trace elements, and 10 parts of brown algae oligosaccharide to 500 parts of deionized water, and heat and stir to promote dissolution;

[0098] (2) After the solution is cooled, 10 parts of a compound fertilizer inhibitor is added, stirred evenly, and filtered to obtain a water-soluble fertilizer containing brown algae oligosaccharides.

[0099] The weight ratio of the chelated trace elements is: EDTA-Fe: EDTA-Mn: EDTA-Zn: EDTA-Cu: EDTA-Mo: EDTA-B = 10:10:10:2:1:0.5;

[0100] The compound fertilizer inhibitor consists of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 1:1.

[0101] Comparative Example 3

[0102] 1. Preparation method of brown algae oligosaccharide

[0103] (1) Wash fresh Sargassum to remove impurities and surface salt, dry and grind into powder;

[0104] (2) 50 g of Sargassum powder was added to a composite enzymatic hydrolysate consisting of 2% cellulase, 2% pectinase, 2% xylanase, and 2% α-amylase, with a material-liquid mass ratio of 1:19 g / ml, an enzymatic hydrolysis temperature of 37 °C, an enzymatic hydrolysis pH of 7, and an enzymatic hydrolysis time of 10 h;

[0105] (3) Filter the enzymatic hydrolyzate to remove the residue, add 80% ethanol solution to the filtrate for alcohol precipitation, and centrifuge at 8000 rpm / min for 5 minutes after precipitation to obtain crude fucoidan;

[0106] (4) Add 4% sulfuric acid solution to the crude fucoidan, with the material-liquid ratio of crude fucoidan to acid solution being 1:50. After the solution is mixed, heat it to 100°C and acid hydrolyze it for 3 hours.

[0107] (5) adjusting the pH of the acid hydrolyzate to neutral with ammonia water to obtain a brown algal oligosaccharide solution;

[0108] (6) The brown algae oligosaccharide solution was concentrated under reduced pressure at 70°C to obtain brown algae oligosaccharide.

[0109] 2. Water-soluble fertilizer containing brown algae oligosaccharides

[0110] (1) Add 250 parts of urea, 200 parts of monoammonium phosphate, 250 parts of potassium sulfate, 55 parts of chelated trace elements, and 10 parts of brown algae oligosaccharide to 500 parts of deionized water, and heat and stir to promote dissolution;

[0111] (2) After the solution is cooled, 10 parts of a compound fertilizer inhibitor is added, stirred evenly, and filtered to obtain a water-soluble fertilizer containing brown algae oligosaccharides.

[0112] The weight ratio of the chelated trace elements is: EDTA-Fe: EDTA-Mn: EDTA-Zn: EDTA-Cu: EDTA-Mo: EDTA-B = 10:10:10:2:1:0.5;

[0113] The compound fertilizer inhibitor consists of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 1:1.

[0114] Comparative Example 4

[0115] 1. Add 250 parts of urea, 200 parts of monoammonium phosphate, 250 parts of potassium sulfate, and 55 parts of chelated trace elements to 500 parts of deionized water, and heat and stir to promote dissolution;

[0116] 2. After the solution is cooled, add 10 parts of compound fertilizer inhibitor, stir evenly and filter to obtain a water-soluble fertilizer containing inhibitor.

[0117] The weight ratio of the chelated trace elements is: EDTA-Fe: EDTA-Mn: EDTA-Zn: EDTA-Cu: EDTA-Mo: EDTA-B = 10:10:10:2:1:0.5;

[0118] The compound fertilizer inhibitor consists of n-butylthiophosphoric acid triamine and 3,4-dimethylpyrazole phosphate in a weight ratio of 1:1.

[0119] Test Example 1

[0120] The average degree of polymerization (DP) indicates the amount of fucoidan in the product. A lower DP indicates a higher fucoidan content, corresponding to a higher yield. Therefore, the extraction efficiency of fucoidan in Examples 1-3 and Comparative Examples 1-4 was compared using the average DP: average DP = reducing sugar content / total sugar content × 100%. The results are shown in Table 1.

[0121] The total sugar content in the samples was determined by the phenol-sulfuric acid method, and the reducing sugar content was determined by the m-hydroxybiphenyl method.

[0122] Table 1 Average degree of polymerization of brown algal oligosaccharides in each test group

[0123]

[0124] It can be seen from the data in Table 1 that compared with Comparative Example 1 (using only enzymatic hydrolysis), the average degree of polymerization of brown algae oligosaccharides in Examples 1-3 is significantly reduced, indicating that the composite enzymatic hydrolysis-alcohol precipitation-acid hydrolysis method adopted by the present invention has a higher extraction efficiency of brown algae oligosaccharides; compared with Comparative Example 2 (using only cellulase and pectinase), the average degree of polymerization of brown algae oligosaccharides in Examples 1-3 is significantly reduced, indicating that the composite enzyme combination selected by the present invention has a higher extraction efficiency; compared with Comparative Example 3 (longer enzymatic hydrolysis time), the average degree of polymerization of brown algae oligosaccharides in Examples 1-3 is not much different, indicating that the enzymatic hydrolysis time of the present invention is appropriate and the extraction time can be reduced.

[0125] Test Example 2

[0126] The effects of different experimental groups of 3,4-dimethylpyrazole phosphate (DMPP) in the water-soluble fertilizer containing brown algae oligosaccharides on the duration of their presence in the soil were compared by laboratory simulation. 30 ml of the water-soluble fertilizers prepared in Examples 1-3 and Comparative Examples 1-4 were applied to 1 kg of soil (the soil was taken from the 0-20 cm tillage layer of the high-standard demonstration field of Xinyangfeng Agricultural Science and Technology Co., Ltd., and the basic physical and chemical properties of the soil were: pH 7.14, nitrate nitrogen 14.58 mg·kg -1 , ammonium nitrogen 4.65 mg·kg -1 , fast-acting phosphorus 268.4 mg kg -1 , fast-acting potassium 513.15 mg·kg -1, organic matter 30.72 mg·kg -1 , bulk density 1.51g·cm -3 ), cultured at 30°C, and the effective DMPP content of the different test groups was measured after 60 days, and the proportion of effective DMPP to initial DMPP was calculated. The specific results are shown in Table 2.

[0127] Table 2 Application effects of water-soluble fertilizer containing brown algae oligosaccharides in each test group

[0128]

[0129] As can be seen from the data in Table 2, the effective DMPP ratios of Examples 1-3 and Comparative Examples 1-3 (containing brown algae oligosaccharides) were significantly increased after 60 days compared with Comparative Example 4 (without adding any brown algae oligosaccharide components), indicating that the brown algae oligosaccharides prepared by the present invention have the function of increasing the duration of the DMPP inhibitor action.

[0130] Test Example 3

[0131] The effects of different experimental groups of water-soluble fertilizers containing brown algae oligosaccharides on the final yield of corn were determined by pot experiments

[0132] The corn variety was 'Xiangyu 655', and the soil was collected from the 0-20 cm tillage layer of the high-standard demonstration field of Xinyangfeng Agricultural Science and Technology Co., Ltd. The basic physical and chemical properties of the soil were: pH 7.14, nitrate nitrogen 14.58 mg·kg -1 , ammonium nitrogen 4.65 mg·kg -1 , fast-acting phosphorus 268.4 mg kg -1 , fast-acting potassium 513.15 mg·kg -1 , organic matter 30.72 mg·kg -1 , bulk density 1.51g·cm -3 .

[0133] After collecting, the soil was free of stones and debris and then sieved through a 2 mm sieve for later use. Corn was sown on April 15, 2022. During the tasseling period, the water-soluble fertilizers prepared in Examples 1-3 and Comparative Examples 1-4 were used in each potted plant by root irrigation at a dosage of 30 ml of water-soluble fertilizer per kg of soil. The plants were harvested on July 23, 2022. Except for the different algal oligosaccharide content in the fertilizer, the other field management measures such as sowing, irrigation, weeding, and pest control were the same. The results of the number of grains per ear, thousand-grain weight, and yield of each group in Examples 1-3 and Comparative Examples 1-4 are shown in Table 3.

[0134] Table 3 Application effect of water-soluble fertilizer containing brown algae oligosaccharide in each test group

[0135]

[0136] As shown in Table 3, compared with Comparative Examples 1-4, the corn yields of Examples 1-3 were significantly improved, indicating that the brown algae oligosaccharides of the present invention can promote crop growth and increase crop yield.

[0137] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An application of brown algae oligosaccharide in increasing the action time of DMPP inhibitor in water-soluble fertilizer, characterized in that: The preparation method of brown algae oligosaccharide comprises: crushing brown algae, adding a composite enzymatic hydrolysis solution for enzymatic hydrolysis, filtering, mixing the filtrate with an ethanol solution for alcohol precipitation, centrifuging, and precipitating crude brown algae polysaccharide; adding an acid solution to the crude brown algae polysaccharide for acid hydrolysis, adjusting the pH value to neutral, centrifuging, and concentrating the supernatant under reduced pressure to obtain the brown algae oligosaccharide; The composite enzymatic hydrolysate is composed of the following composite enzymes in percentage by weight: 1% to 3% cellulase, 1% to 3% pectinase, 1% to 3% xylanase and 1% to 3% α-amylase; The enzymatic hydrolysis has a material-liquid ratio of 1:18-20 g / ml, a temperature of 37-40° C., a pH value of 7-8, and a time of 4-6 h; The acid solution is a sulfuric acid solution with a mass concentration of 3% to 5%; the material-liquid ratio of the crude brown algae polysaccharide to the acid solution is 1:50 to 60 g / ml, the temperature of the acid hydrolysis is 95 to 105° C., and the time is 3 to 4 hours.

2. The use according to claim 1, characterized in that: The volume fraction of the ethanol solution is 75% to 85%, and the volume ratio of the filtrate to the ethanol solution is 1:1 to 1.

2.

3. The use according to claim 1, characterized in that: The temperature of the reduced pressure concentration is 65-75°C.

4. The use according to claim 1, characterized in that: The water-soluble fertilizer comprises the following raw materials in parts by weight: 500-600 parts of desalted water, 230-260 parts of urea, 180-220 parts of monoammonium phosphate, 230-260 parts of potassium sulfate, 50-60 parts of chelated trace elements, 8-13 parts of brown algae oligosaccharide and 8-13 parts of compound fertilizer inhibitor.

5. The use according to claim 4, characterized in that: The chelated trace elements are composed of EDTA-Fe, EDTA-Mn, EDTA-Zn, EDTA-Cu, EDTA-Mo and EDTA-B in a weight ratio of 8-13:8-13:8-13:1-3:0.5-1.5:0.3-0.

8.

6. The use according to claim 4, characterized in that: The compound fertilizer inhibitor is composed of n-butylthiophosphoric acid triamide and 3,4-dimethylpyrazole phosphate in a weight ratio of 0.5-1.5:0.5-1.

5.

7. The use according to any one of claims 4 to 6, characterized in that: The preparation method of the water-soluble fertilizer comprises: mixing urea, monoammonium phosphate, potassium sulfate, chelated trace elements, brown algae oligosaccharide and demineralized water, heating and stirring until dissolved, and adding a compound fertilizer inhibitor after cooling to obtain the water-soluble fertilizer.

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