Organic fertilizer for promoting growth of plant root system and preparation method thereof

Abstract

This invention discloses an organic fertilizer that promotes plant root growth and its preparation method, relating to the fields of agricultural planting and fertilizer processing technology. The organic fertilizer for promoting plant root growth comprises the following components in parts by weight: 60-80 parts fermented organic matrix, 5-15 parts mineral-derived potassium humate, 3-8 parts enzymatically hydrolyzed seaweed extract, 5-10 parts compound amino acid powder, 0.05-0.5 parts root growth promoting factor, 0.5-2 parts microbial inoculant, and 2-5 parts binder. This invention utilizes an indole derivative with a specific structure as the core component, and leverages its unique side chains and functional groups to enhance chemical stability, making it less prone to thermal decomposition during fertilizer granulation and drying processes.

Description

Technical Field

[0001] This invention relates to the field of agricultural planting and fertilizer processing technology, specifically to an organic fertilizer that promotes plant root growth and its preparation method. Background Technology

[0002] Plant roots, as the core organs of crop growth, not only perform the mechanical function of anchoring the plant but also serve as the main gateway for the absorption of soil moisture and mineral nutrients. The development of the root system directly affects the above-ground growth vigor, stress resistance, and ultimately, yield and quality of the crop. In modern agricultural production, organic fertilizers are widely used because they can improve soil physicochemical properties and regulate the rhizosphere microecological environment. Traditional organic fertilizers are usually composed of fermented organic substrates, humic acids, amino acids, and microbial agents. While they can provide nutrients and improve the soil environment to some extent, their effect on inducing the germination of plant roots, especially lateral and adventitious roots, is relatively mild and has a long onset period, often failing to meet the urgent need for rapid root development during the transplanting or seedling stage.

[0003] To compensate for this deficiency, existing technologies often attempt to add exogenous root growth promoters to organic fertilizers, mainly involving synthetic auxin-like regulators or their analogues, such as indoleacetic acid, indolebutyric acid, or naphthaleneacetic acid. Although these conventional growth regulators show promise in promoting cell division and elongation in laboratory settings, they reveal significant technical drawbacks in industrial fertilizer production and field applications. First, traditional indole-like auxins are chemically unstable and have poor thermal stability, making them prone to oxidative decomposition during the high-temperature granulation and drying processes of organic fertilizers, leading to a substantial reduction in the content of effective components in the finished fertilizer. Second, when these fertilizers are applied to the soil, conventional regulators are easily degraded rapidly by soil pH, light, and oxidases secreted by rhizosphere microorganisms, resulting in short half-lives in the soil and difficulty in maintaining a long-lasting and stable stimulating concentration around the roots. Furthermore, some general-purpose regulators have narrow bioactivity thresholds; increasing the dosage to achieve rapid effects can easily lead to hormonal imbalances in plants, causing negative effects such as growth inhibition or even phytotoxicity.

[0004] In summary, existing organic fertilizers for promoting plant root growth suffer from poor processing stability, short field retention, and low bioavailability due to the limitations of the chemical structure of the active ingredients used. Therefore, developing a novel root growth promoting ingredient that is chemically stable, resistant to high-temperature processing, resistant to soil enzymatic degradation, and possesses high biological activity, and scientifically compounding it with organic nutrient substrates to achieve efficient and long-lasting induction of plant root growth, is a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an organic fertilizer that promotes plant root growth and its preparation method, in order to solve the technical problems in the prior art where root growth promoting factors are chemically unstable, easily oxidized and decomposed, have a short duration of effect, and have low bioavailability, resulting in the fertilizer's effect on promoting crop root development being insignificant and unsustainable.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides an organic fertilizer that promotes plant root growth, the raw materials of which include the following components in parts by weight:

[0008] 60-80 parts of fermentation organic substrate;

[0009] 5-15 parts of mineral-derived potassium humate;

[0010] 3-8 parts of enzymatically hydrolyzed seaweed extract;

[0011] 5-10 parts of compound amino acid powder;

[0012] Root growth promoting factor 0.05-0.5 parts;

[0013] 0.5-2 parts of microbial inoculant;

[0014] 2-5 parts adhesive.

[0015] Furthermore, the root growth promoting factor is 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid.

[0016] Furthermore, the fermented organic substrate is selected from one or more of fermented sheep manure, fermented soybean meal, fermented mushroom residue, fermented cow manure, and fermented chicken manure, and the moisture content is controlled at 20-30%.

[0017] Furthermore, the preparation method of the fermented organic substrate is as follows: Mix the selected raw materials, adjust the carbon-nitrogen ratio to 25-30:1, adjust the moisture content to 50-60%, add 0.1-0.2% of the raw material mass of organic material composting agent for composting fermentation; when the temperature of the pile rises to 55-65℃, maintain it for 5-7 days, turning the pile every 2-3 days during this period, and after fermentation, age it for 5-7 days, then crush it to obtain the final product.

[0018] Furthermore, the potassium fulvic acid from the mineral source is potassium fulvic acid powder with a fulvic acid content of greater than 50%.

[0019] Furthermore, the enzymatically hydrolyzed seaweed extract is selected from one or more of the following: *Sargassum fusiforme* enzymatically hydrolyzed extract, ... and kelp enzymatically hydrolyzed extract.

[0020] Furthermore, the preparation method of enzymatic hydrolysis seaweed extract is as follows: after washing and removing impurities from seaweed, it is crushed, water is added and ground into a slurry, the pH is adjusted to 6.5-7.5, a complex enzyme preparation containing cellulase, alginate lyase and protease is added, and enzymatic hydrolysis is carried out at 45-50℃ for 3-5 hours. The enzymatic hydrolysate is then inactivated at 90℃, filtered, centrifuged and spray-dried to obtain the final product.

[0021] Furthermore, the composite amino acid powder is composed of glutamic acid, aspartic acid, leucine, and lysine mixed in a mass ratio of 3-4:2-3:1-2:1-2.

[0022] Furthermore, the microbial agent is selected from one or more of Bacillus subtilis powder, Bacillus amyloliquefaciens powder, Trichoderma harzianum powder, and gelatinous Bacillus powder, and the effective viable count is greater than 2 billion per gram.

[0023] Furthermore, the binder is selected from one or more of bentonite, kaolin, and sodium carboxymethyl cellulose.

[0024] The present invention also provides a method for preparing the above-mentioned organic fertilizer that promotes plant root growth, comprising the following steps:

[0025] Step 1, Preparation of premix: Place the root growth promoting factor and compound amino acid powder into a high-speed mixer and mix for 10-15 minutes at a speed of 500-800 rpm to obtain the primary premix; then mix the primary premix with enzymatically hydrolyzed seaweed extract and mineral-derived potassium humate and mix for 15-20 minutes at a speed of 300-500 rpm to obtain the secondary premix;

[0026] Step 2, Matrix treatment and mixing: The fermentation organic matrix is ​​pulverized to pass through a 40-60 mesh sieve; the pulverized fermentation organic matrix is ​​fed into a mixer, and the secondary premix and binder prepared in Step 1 are added. The mixture is stirred evenly to obtain a mixed material, and the mixing time is 20-30 minutes; wherein, the binder is mixed with 0.8-1.2 times its mass of water before being added to form a wet powder binder, in order to improve granulation and ensure uniform dispersion of active ingredients.

[0027] Step 3, Granulation and Drying: The mixture obtained in Step 2 is granulated, and the resulting granules are sent to a dryer for drying. The inlet air temperature is 60-80℃, the outlet temperature is 40-50℃, and the granules are dried until the moisture content is 15-20%.

[0028] Step 4, Cooling and Inoculation: Cool the dried granules to room temperature. During or after cooling, attach the microbial agent to the surface of the granules and then sieve them. To avoid reducing the number of viable bacteria due to high temperature, the granules should be cooled to no higher than 35°C before inoculation.

[0029] Furthermore, the wet powder binder is preferably prepared at a mass ratio of binder:water = 1:(0.8-1.2), and is stirred until it can be formed into a ball by hand and easily dispersed by light touch before being added to a mixer to improve particle strength and reduce pulverization during the granulation process.

[0030] Furthermore, the microbial agent is preferably sprayed as a bacterial suspension when the particles are cooled to 25-35°C; the bacterial suspension can be prepared by mixing the microbial agent and sterile water at a mass ratio of 1:(5-10), and the spray volume is 5-10L per 100kg of dried particles, and the agent is evenly attached under rolling or turning conditions to ensure the number of live bacteria and the uniformity of attachment.

[0031] The present invention provides an organic fertilizer that promotes plant root growth, which falls under the fields of organic fertilizer and microbial fertilizer manufacturing.

[0032] The organic fertilizer for promoting plant root growth described in this invention exhibits a significant synergistic effect among its components. Firstly, the root growth promoting factor 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid, as the core functional component, significantly improves the molecule's hydrophilicity and transport efficiency within the plant's vascular bundles by introducing a side chain containing an amide bond and a carboxyl group at the C3 position of the indole skeleton and a carboxyl group at the C5 position. Simultaneously, the steric hindrance effect formed by this specific stereochemical structure significantly enhances its resistance to indoleacetic acid oxidase in plants, thereby prolonging its half-life in the rhizosphere and within the plant, ensuring continuous stimulation of root cell division and elongation. Building upon this foundation, the abundant carboxyl and phenolic hydroxyl groups in mineral-derived potassium humate can form supramolecular complexes with the aforementioned root growth promoting factors. This complexation not only provides a physical shield for the promoting factors, preventing their rapid degradation by enzymes produced by soil microorganisms, but also constructs a slow-release carrier system for the active ingredients. Simultaneously, the naturally occurring cytokinins in enzymatically hydrolyzed seaweed extracts and the indole derivatives of this invention form an optimized auxin-cytokinin hormone balance at the plant physiological level. These two factors synergistically induce the formation of lateral root primordia and adventitious roots, effectively mitigating the risk of short, thick, and deformed roots that may result from a single high concentration of auxin. Furthermore, the compound amino acid powder and fermented organic matrix provide directly absorbable carbon and nitrogen sources and energy substrates for the rapid root construction process activated by signaling molecules. Combined with the dominant microbial community formed in the rhizosphere by microbial agents, this improves the rhizosphere microecological environment, thus achieving comprehensive synergy from signaling molecule induction to microenvironment optimization and nutrient supply, significantly enhancing the growth and vitality of plant roots.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. This invention uses an indole derivative with a specific structure as the core component, and utilizes the special side chains and functional groups in its molecule to enhance chemical stability, making it less prone to thermal decomposition during fertilizer granulation and drying processes. At the same time, this structure significantly improves resistance to oxidases in plants, effectively prolonging the half-life and duration of action of the active ingredient in the rhizosphere and in plants, thereby continuously and stably stimulating the division and elongation of plant root cells.

[0035] 2. This invention scientifically combines specific root growth promoting factors with mineral-derived potassium humate and enzymatically hydrolyzed seaweed extract. The potassium humate's complexing effect provides a physical shield and slow-release carrier for the active factors, while the natural active substances in the enzymatically hydrolyzed seaweed extract regulate the plant's hormonal balance. This synergistic effect effectively induces the formation of lateral root primordia and adventitious roots, avoiding the root problems of short, thick, or deformed roots that may result from using high-concentration growth regulators alone, thus promoting a more developed and healthy root system.

[0036] 3. The fermented organic substrate, compound amino acid powder, and microbial inoculant in the formula of this invention work synergistically to provide a direct source of carbon and nitrogen for root system development, improve the rhizosphere microecological environment, and inhibit soil-borne diseases, thereby increasing the survival rate of crops after transplanting and their resistance to adverse conditions such as drought and low temperature. Furthermore, the multi-stage premixing, low-temperature drying, and cooling followed by microbial inoculation process ensures the uniform dispersion of trace active ingredients in the substrate and maximizes the preservation of the enzymatic hydrolysis products and the biological activity of the microorganisms. Attached Figure Description

[0037] Figure 1 This is a grouped bar chart (ng / gFW) showing the IAA and ZT contents of the embodiments and comparative examples of the present invention. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Preparation Example 1

[0040] Preparation of 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid:

[0041] The molecular structure of 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid is:

[0042] .

[0043] first step:

[0044] Compound 1: 3-(2-Carboxyethyl)-1H-indole-5-carboxylic acid;

[0045] Compound 2: Glycine ethyl ester hydrochloride;

[0046] Compound 3: 3-(3-((2-ethoxy-2-oxoethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid;

[0047] At room temperature, 4.00 g of compound 1 and 60 mL of anhydrous DMF were added to a flask and stirred until evenly dispersed. Then, 2.63 g of compound 2 and 2.78 g of HOBt were added. The reaction flask was placed in an ice-water bath at 0°C for 15 minutes. While stirring, 10.5 mL of DIPEA was slowly added dropwise using a syringe. After the addition was complete, 3.95 g of EDCI·HCl was added in portions. After the addition was complete, the mixture was stirred at 0°C for 1 hour. Then, the ice bath was removed, and the reaction system was allowed to warm naturally to room temperature. The reaction was continued with stirring under nitrogen protection for 16 hours. After the reaction was complete, the reaction solution was slowly poured into 300 mL of ice water, and 1 M HCl was added while stirring to adjust the pH to 3-4. Precipitation may occur at this point. Extraction was performed using ethyl acetate (3 × 100 mL). The organic phases were combined. The mixture was washed successively with water (2 × 100 mL) and saturated brine (1 × 100 mL). The organic phase was dried over anhydrous sodium sulfate for 30 minutes and filtered to remove the desiccant. The filtrate was concentrated by rotary evaporation under reduced pressure to obtain the crude product. The crude product was purified by rapid silica gel column chromatography. The stationary phase was silica gel; the eluent was DCM:MeOH = 50:1 to 20:1 (gradient elution). The fraction containing the target product was collected, concentrated under reduced pressure, and dried under vacuum to obtain 3.59 g of solid powder compound 3.

[0048] Step 2: At room temperature, add 3.59 g of compound 3 and 36 ml of THF to a round-bottom flask and stir to disperse evenly. Dissolve 1.66 g of LiOH·H2O in 12 ml of deionized water to prepare a clear aqueous solution. Cool the flask in an ice-water bath at 0°C for 10 minutes. Then, slowly add the lithium hydroxide aqueous solution dropwise to the THF reaction solution using a pipette. After the addition is complete, remove the ice bath and allow the reaction system to naturally warm to room temperature, stirring for 4 hours. After the reaction is complete, remove most of the THF from the reaction mixture using a rotary evaporator under reduced pressure, leaving an aqueous residue. Dilute the residue with 20 mL of water, then wash the aqueous phase with ethyl acetate (20 mL × 1). Place the aqueous phase in an ice bath at 0°C and stir, slowly adding 1 M HCl aqueous solution to adjust the pH to 2-3. Extract the acidic aqueous phase thoroughly with EtOAc (50 mL × 3). The organic phases were combined and washed successively with small amounts of water (20 mL) and saturated brine (20 mL), dried over anhydrous Na₂SO₄, and filtered. The filtrate was concentrated under reduced pressure to obtain the crude product. A small amount of diethyl ether (15 mL) was added to the crude product for slurrying, followed by sonication for 5 minutes and filtration. The filter cake was washed with cold diethyl ether and dried under vacuum to obtain 2.74 g of 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid.

[0049] Structural assessment data:

[0050] 3-(3-((2-ethoxy-2-oxoethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid 1 HNMR (DMSO-d6)δ:

[0051] 12.45(s,1H),11.22(s,1H),8.32(t,1H),8.18(d,1H),7.71(dd,1H),7.40(d,1H ),7.23(d,1H),4.09(q,2H),3.82(d,2H),2.96(t,2H),2.53(t,2H),1.18(t,3H).

[0052] 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid 1 HNMR (DMSO-d6)δ:

[0053] 12.55(s,2H),11.24(s,1H),8.21(t,1H),8.18(s,1H),7.72(dd,1H),7.42(d,1H),7.21(d,1H),3.76(d,2H),3.02(t,2H),2.56(t,2H).

[0054] Example 1

[0055] This embodiment provides a mass fraction of raw materials for an organic fertilizer that promotes plant root growth and its preparation:

[0056] 1. Raw material components by weight:

[0057] 70 parts of fermented organic substrate;

[0058] 10 parts of mineral-derived potassium humate;

[0059] Five portions of enzymatically hydrolyzed seaweed extract;

[0060] 8 parts of compound amino acid powder;

[0061] 0.1 parts of root growth promoting factor;

[0062] One part of microbial inoculant;

[0063] 3 parts adhesive.

[0064] The root growth promoting factor is 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid, which is synthesized according to the method described in Preparation Example 1.

[0065] The fermented organic substrate is selected from fermented sheep manure, and its moisture content is controlled at 25%.

[0066] The preparation method of the fermented sheep manure is as follows: Fresh sheep manure is crushed to a particle size of 10-35mm, and corn cob powder crushed to 20 mesh is added to adjust the carbon-nitrogen ratio to 28:1 and the moisture content to 55% (by mass) to make the pH value of the material neutral; 1.5L VT-1000 inoculant (purchased from Beijing Wotu Tiandi Biotechnology Co., Ltd.) and 1.5kg brown sugar (food grade) are prepared for every 1000kg of dry sheep manure (on a dry basis); the brown sugar is first fully dissolved in 30℃ warm water (accounting for 50% of the total dilution water for the inoculant), then the VT-1000 inoculant is added and stirred well, followed by the remaining dilution water (the total volume of the inoculation solution is 300L, i.e., 300kg of inoculation solution for every 1000kg of dry material); the prepared reddish-brown inoculant solution is evenly poured onto the sheep manure raw material and a horizontal sprayer is used. The ribbon mixer is used to thoroughly mix the bacterial solution and materials for 30 minutes to ensure uniform mixing. The inoculated materials are then piled into a strip-shaped mound, with a height of 80cm and a base width of 130cm. After piling, the materials are covered with a breathable covering (non-woven fabric) to provide appropriate shade. The high-temperature fermentation period lasts for 7 days, during which the temperature at the center of the pile is monitored. When the temperature reaches 60℃, the pile is turned over every 24 hours, with a turning depth of ≥30cm to ensure uniform fermentation inside and out. After turning the pile 4 times, turning is stopped and maintained for 24 hours, at which point fermentation is complete. After fermentation, the materials are evenly spread out in a well-ventilated and rain-sheltered place to age for 6 days. They are then dried at 55℃ until the moisture content drops to 25%, crumbles easily when squeezed, and has no odor. Subsequently, the materials are crushed through a 50-mesh sieve to obtain fermented sheep manure with a moisture content of 25wt%, which is then dried at a low temperature for later use.

[0067] The potassium humate from mineral sources is a powder containing 55% humic acid.

[0068] The enzymatically hydrolyzed seaweed extract is specifically *Tetraphyta buergeriana* enzymatically hydrolyzed extract, prepared as follows: *Tetraphyta buergeriana* is washed and impurities removed, then pulverized to 40 mesh. Water is added at a material-to-liquid ratio of 1:8 (mass-to-volume ratio) to form a slurry. The pH is adjusted to 7.0, and a compound enzyme preparation is added. Enzymatic hydrolysis is performed at 48°C for 4 hours. The compound enzyme preparation consists of: cellulase (enzyme activity 20000 U / g), alginate lyase (enzyme activity 10000 U / g), and protein. The enzyme (enzyme activity 100,000 U / g) was added in a mass ratio of 3:1.5:1, with the total addition amount being 1.2% of the mass of the *Alternaria buergeriana* slurry. After enzymatic hydrolysis, the hydrolysate was heated to 90°C and held for 15 minutes to inactivate the enzyme. Then, it was filtered through a 200-mesh filter and centrifuged at 4000 rpm for 10 minutes to remove the residue. The supernatant was spray-dried (inlet air temperature 180°C, outlet air temperature 80°C) to obtain a powdered enzymatically hydrolyzed seaweed extract with a moisture content ≤8%.

[0069] The composite amino acid powder is composed of glutamic acid, aspartic acid, leucine, and lysine mixed in a mass ratio of 3.5:2.5:1.5:1.5.

[0070] The microbial agent is Bacillus subtilis wettable powder with an effective viable count of 5 billion CFU / g.

[0071] The binder is bentonite.

[0072] 2. Preparation method:

[0073] Step 1, Preparation of premix: 0.1 parts of root growth promoting factor and 8 parts of compound amino acid powder were added to a high-speed mixer (double helix conical mixer) and mixed for 12 minutes at 600 rpm to obtain primary premix; then, the primary premix was mixed with 5 parts of enzymatically hydrolyzed seaweed extract and 10 parts of mineral-derived potassium humate and mixed for 18 minutes at 400 rpm to obtain secondary premix; the ambient temperature was controlled at 25±5℃ and the relative humidity ≤60% during the mixing process.

[0074] Step 2, Matrix Treatment and Mixing: 70 parts of fermented organic matrix were pulverized and passed through a 50-mesh sieve; 3 parts of bentonite were mixed with 1.0 times its weight of deionized water and stirred into a wet powder binder (it can be formed into a clump when squeezed by hand, but crumbles easily when touched); the pulverized fermented organic matrix was fed into a horizontal ribbon mixer, and the secondary premix prepared in Step 1 and the wet powder binder were added. The mixture was stirred and mixed at room temperature for 25 minutes to obtain a mixture with a mixing uniformity coefficient of variation ≤ 7%;

[0075] Step 3, Granulation and Drying: The mixture obtained in Step 2 is fed into a disc granulator (disc diameter 2.0m, rotation speed 15 rpm, inclination angle 45°) for granulation. During the granulation process, an appropriate amount of deionized water is sprayed (addition amount is 5% of the mass of the mixture) to adjust the granulation humidity. The obtained granules (particle size 3-5mm) are sent to a rotary dryer for drying. The drying inlet air temperature is controlled at 70℃ and the outlet temperature is controlled at 45℃. The granules are dried until the moisture content is 18wt%.

[0076] Step 4, Cooling and Inoculation: The dried granules are fed into a counter-current cooler and cooled to room temperature (30±2℃) under induced draft conditions for 10 minutes. When cooled to 30℃, 1 part of Bacillus subtilis powder is prepared into a bacterial suspension. The specific preparation method is as follows: 1 part of the microbial agent is added to 8 parts of sterile deionized water (preheated to 30℃), and 0.05 parts of food-grade sodium carboxymethyl cellulose is added as a dispersant and stabilizer. The mixture is stirred at 200 rpm for 15 minutes to prepare an effective live bacteria suspension. A homogeneous suspension with a bacterial count of 5 billion CFU / mL was prepared. Using a pressure sprayer (nozzle diameter 0.5 mm, spray pressure 0.3 MPa), 8 L of the above bacterial suspension was evenly sprayed per 100 kg of dried granules. The mixture was sprayed and turned on a rotating bed (rotation speed 5 rpm) to ensure that the bacterial agent was evenly attached to the surface of the granules. After spraying, the mixture was turned for another 5 minutes to ensure uniformity. Finally, the granules were passed through a 4-mesh sieve, inspected, and packaged to obtain the organic fertilizer that promotes plant root growth.

[0077] Example 2

[0078] An organic fertilizer that promotes plant root growth is prepared by replacing Sargassum fusiforme with Sargassum fusiforme in the steps of Example 1, while keeping the rest of the preparation process of the extract unchanged, and obtaining Sargassum fusiforme enzymatic hydrolysis extract. The rest is the same as in Example 1.

[0079] Example 3

[0080] An organic fertilizer that promotes plant root growth, following the steps of Example 1, except that the amount of root growth promoting factor is adjusted from 0.1 parts to 0.2 parts, while the remainder remains the same as in Example 1.

[0081] Example 4

[0082] An organic fertilizer that promotes plant root growth, following the steps of Example 1, except that the binder is replaced with kaolin, while the rest remains the same as in Example 1.

[0083] Comparative Example 1

[0084] An organic fertilizer that promotes plant root growth, following the steps of Example 1, except that the root growth promoting factor is replaced with indole-3-acetic acid, while the rest remains the same as in Example 1.

[0085] Comparative Example 2

[0086] An organic fertilizer that promotes plant root growth, following the steps of Example 1, except that the root growth promoting factor is replaced with 3-(2-carboxyethyl)-1H-indole-5-carboxylic acid (i.e., compound 1 in Preparation Example 1), and the rest remains the same as in Example 1.

[0087] Comparative Example 3

[0088] An organic fertilizer that promotes plant root growth, following the steps of Example 1, except that the root growth promoting factor is replaced with α-naphthaleneacetic acid, while the rest remains the same as in Example 1.

[0089] Comparative Example 4

[0090] An organic fertilizer that promotes plant root growth, following the steps of Example 1, but without the addition of root growth promoting factors, remains the same as in Example 1.

[0091] Performance testing:

[0092] 1. Indoor pot experiment on root growth promotion effect

[0093] The test crop was cucumber (variety: Zhongnong 26). The seeds were surface disinfected (treated with 75% ethanol for 30 seconds, 0.1% mercuric chloride for 10 minutes, and rinsed with sterile water 3 times) and then germinated at a constant temperature.

[0094] Experimental design: A completely randomized block design was adopted, with a total of 8 treatment groups including Examples 1-4 and Comparative Examples 1-4, each with 5 replicates and 10 seedlings per replicate.

[0095] Test method:

[0096] (1) Preparation of seedling substrate: Mix peat moss, vermiculite and perlite in a volume ratio of 3:1:1, sterilize at 121℃ for 30 minutes and then put them into 50-cell seedling trays;

[0097] (2) Fertilization treatment: When the seedlings grow to two leaves and one heart, the fertilizers prepared in Examples 1-4 and Comparative Examples 1-4 are mixed evenly into the seedling substrate at a ratio of 1:100 (fertilizer: substrate, mass ratio); 50g of mixed substrate is applied to each seedling.

[0098] (3) Culture conditions: Cultured in an artificial climate chamber, with a daytime temperature of 25±2℃ and a nighttime temperature of 18±2℃, and a light intensity of 300 μmol·m⁻¹. -2 ·s -1 Photoperiod 14h / 10h (day / night), relative humidity 65%-75%; water with Hogland nutrient solution every 3 days to keep the substrate moist;

[0099] (4) Sampling and measurement: After 14 days of treatment, 5 seedlings were randomly selected from each replicate. The roots were carefully rinsed, the surface moisture was dried, and the following indicators were measured:

[0100] Root biomass: The roots were blanched at 105℃ for 30 min and dried at 80℃ to constant weight. The dry weight was measured and the data are shown in Table 1.

[0101] Root activity assay: The triphenyltetrazolium chloride (TTC) method was used. 0.5 g of root tip was weighed and 5 mL each of 0.4% TTC solution and 1 / 15 mol / L phosphate buffer (pH 7.0) were added. The mixture was incubated at 37℃ in the dark for 1 h. The reaction was terminated by adding 2 mL of 1 mol / L sulfuric acid. Extraction was performed with ethyl acetate, and the absorbance was measured at 485 nm. The TTC reduction amount (μg·g⁻¹) was calculated. -1 ·h -1 The data is shown in Table 1.

[0102] Endogenous hormone content in roots: Indoleacetic acid (IAA) and zeatin (ZT) were determined by enzyme-linked immunosorbent assay (ELISA), and the data are shown in Table 1.

[0103] Table 1

[0104]

[0105] When the dosage of root growth promoting factors increased, their promoting effect on the root development of cucumber seedlings showed a positive increasing trend. The effects of enzymatic extracts from different seaweed sources on fertilizer efficacy tended to be similar. The extracts of *Sargassum fusiforme* and *Sargassum fusiforme* showed the same and / or similar effects in promoting root biomass accumulation, enhancing root metabolic activity, and regulating endogenous hormone levels.

[0106] Adjusting the type of binder has a relatively limited impact on the overall fertilizer efficiency. Kaolin and bentonite, as inert carrier matrices, have similar functions in maintaining the uniform dispersion of active ingredients and particle formation.

[0107] Regarding the structure-activity relationship, the complete molecule containing the amide bond side chain (the promoting factor of this invention) exhibits significantly enhanced root-promoting activity compared to its synthetic precursor (the intermediate containing only the carboxyethyl side chain), demonstrating the necessity of introducing the amide bond and terminal carboxyl group in the molecular design, enhancing its resistance to oxidases in plants, thereby prolonging its half-life and improving its bioavailability.

[0108] The root biomass accumulation, metabolic activity, and endogenous hormone levels in the traditional indoleacetic acid and naphthaleneacetic acid treatment groups were significantly lower than those in the embodiments of the present invention. This is consistent with the mechanisms that facilitate thermal decomposition during processing, rapid degradation after soil application, and the tendency to induce hormonal imbalances leading to root morphological deformities. In contrast, the factors of the present invention achieve synergistic optimization in terms of processing stability, environmental persistence, and physiological activity.

[0109] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An organic fertilizer for promoting the growth of plant root systems, characterized by, Its raw materials include the following components in parts by weight: 60-80 parts of fermentation organic substrate; 5-15 parts of mineral-derived potassium humate; 3-8 parts of enzymatically hydrolyzed seaweed extract; 5-10 parts of compound amino acid powder; Root growth promoting factor 0.05-0.5 parts; 0.5-2 parts of microbial inoculant; 2-5 parts adhesive; The root growth promoting factor is 3-(3-((carboxymethyl)amino)-3-oxopropyl)-1H-indole-5-carboxylic acid.

2. The organic fertilizer for promoting the growth of plant root system according to claim 1, characterized in that, The fermented organic substrate is selected from one or more of fermented sheep manure, fermented soybean meal, fermented mushroom residue, fermented cow manure, and fermented chicken manure, and has a moisture content of 20-30%.

3. The organic fertilizer for promoting the growth of plant root system according to claim 1, characterized in that, The potassium humate from mineral sources is potassium humate powder from mineral sources with a humic acid content of greater than 50%. The enzymatically hydrolyzed seaweed extract is selected from one or more of the following: Sargassum enzymatically hydrolyzed extract, ... and kelp enzymatically hydrolyzed extract.

4. The organic fertilizer for promoting the growth of plant root system according to claim 1, characterized in that, The composite amino acid powder is composed of glutamic acid, aspartic acid, leucine, and lysine mixed in a mass ratio of 3-4:2-3:1-2:1-2.

5. The organic fertilizer for promoting the growth of plant root system according to claim 1, characterized in that, The microbial agent is selected from one or more of Bacillus subtilis powder, Bacillus amyloliquefaciens powder, Trichoderma harzianum powder, and gelatinous Bacillus powder, and the effective viable count is greater than 2 billion per gram; The binder is selected from one or more of bentonite, kaolin, and sodium carboxymethyl cellulose.

6. A method for preparing an organic fertilizer for promoting plant root growth as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1, Preparation of premix: Root growth promoting factor is mixed with compound amino acid powder to obtain primary premix; then the primary premix is ​​mixed with enzymatically hydrolyzed seaweed extract and mineral potassium humate to obtain secondary premix; Step 2, substrate treatment and mixing: After crushing the fermented organic substrate, feed it into a mixer, add the secondary premix and binder prepared in Step 1, and stir evenly to obtain a mixture. Step 3, Granulation and Drying: The mixture obtained in Step 2 is granulated, and the resulting granules are sent to a dryer for drying until the moisture content of the granules is 15-20%. Step 4, Cooling and Inoculation: Cool the dried granules to room temperature and not higher than 35°C. During or after cooling, attach the microbial agent to the surface of the granules. After sieving, the organic fertilizer that promotes plant root growth is obtained. The adhesive is mixed with 0.8-1.2 times its mass of water before being added to form a wet powder adhesive.

7. The method for preparing an organic fertilizer that promotes plant root growth according to claim 6, characterized in that, In step one, the root growth promoting factor and compound amino acid powder are placed in a high-speed mixer and mixed for 10-15 minutes at a speed of 500-800 rpm; when the primary premix is ​​mixed with enzymatically hydrolyzed seaweed extract and mineral potassium humate, it is mixed for 15-20 minutes at a speed of 300-500 rpm.

8. A method for preparing an organic fertilizer that promotes plant root growth according to claim 6, characterized in that, In step two, the fermentation organic substrate is pulverized to pass through a 40-60 mesh sieve, and the mixing time is 20-30 minutes; in step three, the drying inlet air temperature is 60-80℃, and the outlet temperature is 40-50℃. In step three, the microbial agent is sprayed in the form of a bacterial suspension when the particles are cooled to 25-35°C; the bacterial suspension is obtained by mixing the microbial agent and sterile water at a mass ratio of 1:(5-10), and the spray volume is 5-10L per 100kg of particles.

9. A method for preparing an organic fertilizer that promotes plant root growth according to claim 6, characterized in that, The preparation method of the fermented organic substrate is as follows: mix the raw materials, adjust the carbon-nitrogen ratio to 25-30:1, adjust the moisture content to 50-60%, add 0.1-0.2% of the raw material mass of organic material composting agent for composting and fermentation, maintain the temperature of the pile at 55-65℃ for 5-7 days, turn the pile over every 2-3 days during the period, and after fermentation, age for 5-7 days, and then crush to obtain the final product.

10. The method of claim 6, wherein the organic fertilizer is prepared by the steps of: The preparation method of the enzymatically hydrolyzed seaweed extract is as follows: after washing and removing impurities, the seaweed is crushed, water is added and ground into a slurry, the pH is adjusted to 6.5-7.5, a compound enzyme preparation containing cellulase, alginate lyase and protease is added, and the seaweed is enzymatically hydrolyzed at 45-50℃ for 3-5 hours. The hydrolysate is then inactivated at 90℃, filtered, centrifuged and spray-dried to obtain the final product. ​

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