An ecological control method for diseases and insect pests of fruit tree seedlings

Abstract

The application relates to the technical field of fruit tree cultivation and seedling raising, and discloses an ecological prevention and treatment method for diseases and insect pests of fruit tree seedlings, which comprises the following steps: mixing polyvinyl alcohol with water to prepare a protective colloid base solution, adding potassium fulvate, oxymatrine and amino oligosaccharin to prepare a drug-loaded solution, adding a potassium silicate aqueous solution to blend to prepare a stable storage silicate sol, mixing the silicate sol with cold water and adding ammonium bicarbonate to apply the silicate sol to a rhizosphere area of fruit tree seedlings in a rheological operation window period. The application utilizes the kinetic coupling of the endothermic decomposition of ammonium bicarbonate to produce gas and the dehydration phase change process of potassium silicate to generate a porous and interconnected silicate gel barrier in situ in the rhizosphere. The network builds an ecological planting protective layer, can long-acting intercept effective components and block the invasion of harmful organisms, and can maintain the oxygen mass transfer channel for normal respiration of roots, overcomes the defect that conventional dense coating causes seedlings to lack oxygen and to be soaked in roots, and improves the survival rate of continuous cropping and heavy stubble seedlings.

Description

Technical Field

[0001] This invention relates to the field of fruit tree cultivation and seedling technology, specifically to an ecological method for the prevention and control of diseases and pests in fruit tree seedlings. Background Technology

[0002] In the process of replanting and seedling transplanting in old orchards, the deterioration of the rhizosphere microenvironment caused by soil-borne fungi and root-knot nematodes is the core factor leading to low seedling survival rates. Conventional cultivation management often uses chemical agents for root dipping or root zone soil irrigation. The free active ingredients of these agents are easily leached and lost in the soil matrix with irrigation water, resulting in a short duration of rhizosphere defense, which cannot meet the needs of long-term continuous cropping and seedling production.

[0003] To overcome the problem of rapid loss of active ingredients, some cultivation techniques have attempted to introduce inorganic silicate materials into the rhizosphere of seedlings, aiming to form a physical film barrier through in-situ solidification to encapsulate the agents. Although the dense silicate gel formed in this way spatially blocks the physical contact path between pathogens and roots, its dense, non-porous structure directly blocks the interface between the macropores of the soil and the root epidermis, cutting off the physical channels for oxygen diffusion and heat and mass exchange between the plant roots and the external atmosphere. This leads to a low-oxygen microenvironment in the roots, forcing them to switch to anaerobic respiration and metabolism and accumulate harmful metabolites, ultimately causing large-scale hypoxia, root rot, and physiological necrosis in seedlings.

[0004] The aforementioned in-situ coating materials still face insurmountable technological obstacles in actual field planting operations. Bio-derived extracts with disease-preventing and growth-promoting effects are typically weakly acidic. Direct mixing with strongly alkaline silicate precursors easily triggers severe electrostatic neutralization and salting-out effects, causing instantaneous irreversible flocculation of the dispersion system, rendering it unusable for commercial storage and transportation. If field-prepared formulation is used instead, the silicate cross-linking phase transition rate driven by normal ambient temperatures is extremely rapid, causing a sudden jump in the apparent viscosity of the mixed liquid within minutes. Due to the lack of a sufficient rheological window, the fluid cross-links and thickens before penetrating the target soil layer of the rhizosphere or uniformly adhering to the bare root surface. This directly leads to interruptions in planting operations, blockage of application probes, and gaps and defects in the rhizosphere protective coating, making it unsuitable for the large-scale planting needs of fruit tree seedlings. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an ecological control method for diseases and pests in fruit tree seedlings. It solves the problem that conventional fruit tree seedlings are prone to low survival rates due to pathogen infection of the rhizosphere microenvironment when planted in continuous cropping. Existing root physical coating or soil conditioning methods can block the oxygen transport channels required for normal plant respiration, causing seedling hypoxia and root rot, and are difficult to consider the construction window required for field planting.

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

[0007] In a first aspect, the present invention provides an ecological control method for diseases and pests in fruit tree seedling cultivation, employing the following technical solution:

[0008] A protective colloidal base solution was prepared by mixing and dissolving polyvinyl alcohol with water.

[0009] Potassium humate, matrine, and amino oligosaccharide were added to the protective colloidal base solution to prepare the drug-loaded solution;

[0010] A potassium silicate aqueous solution was added to the drug-carrying solution and mixed to obtain a silicate sol;

[0011] A mixture of silicate sol and water was prepared by adding ammonium bicarbonate.

[0012] Apply the mixture to the rhizosphere of the fruit tree seedlings.

[0013] By adopting the above technical solution, and using polyvinyl alcohol to construct the protective colloid and ammonium bicarbonate as the on-site gas generation source, the room temperature storage stability of silicate sol is extended, and a porous, permeable gel barrier is formed in situ in the rhizosphere. The physical and chemical reaction mechanism of this solution includes the following steps:

[0014] Step 1: Construction of steric hindrance for the protective colloid. Potassium silicate aqueous solution is strongly alkaline. When it comes into direct contact with a weakly acidic agent containing alkaloids, electrostatic neutralization and salting-out effects occur, causing instantaneous flocculation of silica gel. Polyvinyl alcohol polymers dissolve in water to form long-chain spatial networks, and potassium humate is adsorbed into these polymer networks. This structure forms a physical isolation layer between the strongly alkaline silicate ions and matrine, altering the kinetic state of the system and maintaining the multi-component suspension in a metastable colloidal state, preventing macroscopic phase separation or irreversible cross-linking of silicates.

[0015] Step 2: Kinetic coupling of in-situ gas generation and condensation phase transition. After the mixed solution is injected into the rhizosphere soil of the fruit trees, the soil background temperature triggers the endothermic decomposition of ammonium bicarbonate.

[0016] The released carbon dioxide gas dissolves in water, producing an acidification effect that causes the system's pH to decrease. Driven by hydrogen ion concentration, potassium silicate undergoes protonation and dehydration condensation of silicate anions.

[0017] The generated active silicic acid undergoes condensation and cross-linking in space to form a three-dimensional gel network containing -Si-O-Si- bonds.

[0018] Step 3: Formation of the permeable physical barrier. The rate of gas molecule evolution is coupled with the rate of silicate cross-linking and curing. Ammonia and carbon dioxide form bubble nuclei within the sol matrix and expand. The cross-linking reaction solidifies and retains the pores within the gel matrix, constructing a connected porous structure. This porous structure overcomes the physical defects of conventional silicate gels, which are dense and block gas, providing oxygen diffusion and heat / mass exchange channels for the rhizosphere microenvironment.

[0019] Meanwhile, the solidified porous gel network retains matrine and amino oligosaccharides in situ, slows down water leaching and loss, and cuts off the physical path for pathogenic fungal zoospores and root-knot nematodes to contact the root epidermis.

[0020] Preferably, the raw material composition of the silicate sol, by mass percentage, is as follows:

[0021] Potassium silicate aqueous solution 12.0wt%-18.0wt%, polyvinyl alcohol 2.0wt%-4.5wt%, potassium humate 6.0wt%-10.0wt%, amino oligosaccharides 1.5wt%-3.0wt%, matrine 0.3wt%-0.8wt%, balance deionized water.

[0022] The sum of the mass percentages of all components is 100 wt%.

[0023] The amount of ammonium bicarbonate added is 2.0 wt%-4.0 wt% of the total mass of the silicate sol. The modulus of the potassium silicate aqueous solution is 2.5-3.0, and the solid content is 38.0 wt%-42.0 wt%.

[0024] By adopting the above technical solution, a dynamic balance between the strength of the gel skeleton and the pore structure can be achieved by limiting the specific component ratio and potassium silicate modulus.

[0025] An aqueous solution of potassium silicate with a modulus of 2.5 to 3.0 provides a suitable concentration of free silicate ions, which generates -Si-O-Si- network skeleton nodes with sufficient yield strength under acidification conditions.

[0026] The mass percentage of polyvinyl alcohol is controlled between 2.0 wt% and 4.5 wt% to form a continuous protective colloid and maintain the rheological properties of the dispersion medium. The amount of ammonium bicarbonate added is controlled between 2.0 wt% and 4.0 wt% to generate an appropriate amount of bubble nucleation source, ensuring that the volume of expanding gas does not exceed the bearing limit of the gel skeleton, thus ensuring the connectivity of the pore structure and preventing internal stress collapse.

[0027] Preferably, in both the steps of preparing the drug-loaded solution and the steps of preparing the silicate sol, the system temperature is controlled at 13℃~17℃. The specific steps for preparing the drug-loaded solution by adding potassium humate, matrine, and amino oligosaccharide to the protective colloidal base solution are as follows:

[0028] Potassium humate was added to a protective colloidal base solution for shear dispersion to obtain a dispersion; matrine and amino oligosaccharide were dissolved in water, and citric acid solution was added dropwise to adjust the pH value to between 5.0 and 5.5 to obtain a weakly acidic solution; the weakly acidic solution was added dropwise to the dispersion to obtain a drug-loaded solution.

[0029] By employing the above technical solution, the thermodynamic temperature of the reaction environment is controlled at 13℃~17℃, reducing the frequency of thermal collisions between silicate ions and protons. Citric acid is added dropwise to adjust the pH of the alkaloid solution, establishing a weakly acidic organic phase. When the droplets are added into the alkaline dispersion system, the stirring shear field ensures a smooth pH gradient transition, suppressing localized reactant supersaturation and preventing early agglomeration of silicates.

[0030] Preferably, in the step of preparing the mixture, the silicate sol is mixed with water at a temperature of 12°C to 18°C ​​at a mass ratio of 1:4 to 1:12. The time interval between the addition of ammonium bicarbonate and the application of the mixture to the rhizosphere of the fruit tree seedlings is controlled within 15 min to 35 min.

[0031] By employing the above technical solution, and through thermodynamic regulation using a water medium within a specific temperature range, the critical point of phase transition is delayed, and the on-site construction operation time is extended. The cold water medium within the range of 12℃ to 18℃ absorbs the heat generated by the dissolution and initial trace decomposition of ammonium bicarbonate, thus inhibiting the forward rate of the decomposition reaction.

[0032] The pH of the system remains relatively stable in the initial stage of mixing, and the apparent viscosity of the silicate sol does not increase abruptly. This thermodynamic control provides the mixing system with a rheological window of 15 to 35 minutes, ensuring that the mixed fluid maintains sufficient fluidity to enter the application equipment or penetrate into the soil capillary pores.

[0033] Preferably, the step of applying the mixture to the rhizosphere of the fruit tree seedlings is as follows: using a spraying device equipped with an injection probe, inserting the probe into the substrate around the fruit tree seedlings at a depth of 5cm to 15cm, and injecting the mixture at an injection pressure of 0.1MPa to 0.2MPa, with a pumping volume of 30mL to 60mL per tree.

[0034] By employing the above technical solution, the effect of targeted spatial distribution of fluid is achieved by limiting various parameters of deep injection. The physical insertion depth of the injection probe provides the initial position of the jet center.

[0035] The pumping pressure of 0.1MPa to 0.2MPa is converted into fluid kinetic energy, overcoming the resistance of soil matrix pores and aggregates. Driven by pressure, the fluid conforms to the matrix pore structure to produce radial and vertical infiltration, reaching the 5cm to 15cm soil layer, adapting to the structure of deep roots during the planting stage, and forming a three-dimensional physical defense barrier in situ.

[0036] Preferably, the step of applying the mixture to the rhizosphere of the fruit tree seedlings is as follows: immerse the roots of the fruit tree seedlings below the surface of the mixture for 3 to 8 seconds, lift them up so that the mixture forms an adhesion layer with a thickness of 0.5 mm to 2.0 mm on the root surface, and then plant them.

[0037] By employing the above technical solution, the surface tension and wettability of the fluid within the rheological window period are utilized to achieve the effect of constructing a continuous adhesion film on the bare root surface. The immersion treatment of 3s to 8s allows the colloidal base solution to fully wet the seedling epidermal cells, and upon lifting, it adheres to the natural shape of the root system to form a liquid film of uniform thickness. During the subsequent soil burial and planting process, the liquid film solidifies in situ, forming a basic isolation layer tightly adhering to the core of the main root.

[0038] Preferably, ammonium bicarbonate undergoes pretreatment before use. The pretreatment steps are as follows:

[0039] Ammonium bicarbonate was placed in a fluidized bed dryer and dried at 30℃~35℃ for 10min~15min.

[0040] By employing the above technical solution, the use of a fluidized bed to remove free water avoids the effect of localized hydrolysis of the reagent. Short-duration hot air fluidization at 30℃~35℃ eliminates water molecules adsorbed on the crystal surface. The drying process maintains the integrity of the ammonium bicarbonate crystal lattice structure, prevents heterogeneous and violent gas generation caused by powder agglomeration during on-site mixing, and improves the uniformity of the final gel pore distribution.

[0041] This invention provides an ecological method for controlling diseases and pests in fruit tree seedling cultivation. It has the following beneficial effects:

[0042] 1. In preparing the silicate sol for wrapping seedling roots, this invention uses polyvinyl alcohol to construct a steric hindrance protective colloid and combines it with a specific low temperature and pH adjustment process. This prevents instantaneous salting-out flocculation when strongly alkaline potassium silicate meets weakly acidic alkaloids, thus successfully breaking the thermodynamic instability of multi-component suspensions. This ensures the long-term storage life of the seedling protection material at room temperature and the highly uniform dispersion of the in-situ film-forming components.

[0043] 2. This invention involves adding a specific ratio of ammonium bicarbonate before planting fruit tree seedlings to initiate an in-situ endothermic decomposition reaction and kinetically couple it with the dehydration and condensation phase transition process of potassium silicate itself. This results in the formation of a large number of interconnected air-permeable pores within the solidified matrix covering the rhizosphere. Therefore, while constructing an ecological isolation barrier, it avoids the technical defects of conventional dense coating materials that easily block the root respiration transport pathways, leading to oxygen deficiency and root rot in plants, thus improving the survival rate of seedlings after planting.

[0044] 3. In the on-site planting preparation stage, the present invention uses cold water for dilution to inhibit the early decomposition rate of ammonium bicarbonate and slow down the drastic fluctuations in the pH of the system. This successfully delays the phase transition critical point where the apparent viscosity of the mixture suddenly increases. Therefore, it provides a sufficient rheological window for field construction operations in fruit tree seedling cultivation, ensuring that the mixed fluid can be successfully injected or dipped to cover the target area of ​​the seedling rhizosphere. Attached Figure Description

[0045] Figure 1 A process flow diagram of the prevention and control method provided in the embodiments of the present invention;

[0046] Figure 2 The apparent viscosity of the mixed system over time is shown in the figure provided in the embodiment of the present invention.

[0047] Figure 3 This is a bar chart comparing the effects of different treatment groups on rhizosphere oxygen mass transfer flux and seedling survival rate, as provided in the embodiments of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only 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.

[0049] Preparation Example 1:

[0050] This preparation example provides a method for preparing silicate sol, including the following steps:

[0051] 782g of deionized water was divided into two parts with a volume ratio of 9:1. The first part of deionized water was added to the reactor and heated to 80°C. 20g of polyvinyl alcohol with an average degree of polymerization of 1600 and a degree of alcoholysis of 87.0% was added and stirred to dissolve. The cooling rate was controlled at 2.0°C / min by jacket temperature control and the temperature was cooled to 13°C to obtain the protective colloidal base liquid.

[0052] Under the condition of maintaining the system temperature at 13℃, 60g of mineral-derived potassium fulvic acid with a dry basis content of 50.0wt% was added to the protective colloidal base liquid for shear dispersion to obtain a dispersion.

[0053] 3g of matrine with a purity of 98.0wt% and 15g of amino oligosaccharide with a number average molecular weight of 1000Da were dissolved in the second part of deionized water, and the pH value was adjusted to 5.0 by adding 0.05mol / L citric acid solution to obtain a weakly acidic solution.

[0054] A weakly acidic solution was added dropwise to the dispersion at a rate of 10 mL / min / kg to obtain a drug-loaded solution. While maintaining the system temperature at 13℃, shear stirring was started and the stirring speed was set to 2000 rpm. 120 g of potassium silicate aqueous solution with a modulus of 2.5 and a solid content of 38.0 wt% was slowly pumped into the system at a pumping rate of 1.0% / min of the total mass volume for shear blending. After degassing, silicate sol was obtained.

[0055] Preparation Example 2:

[0056] This preparation example provides a method for preparing silicate sol, including the following steps:

[0057] 715g of deionized water was divided into two parts with a volume ratio of 9:1. The first part of deionized water was added to the reactor and heated to 85°C. 30g of polyvinyl alcohol with an average degree of polymerization of 1700 and a degree of alcoholysis of 88.0% was added and stirred to dissolve. The cooling rate was controlled at 2.5°C / min by jacket temperature control and the temperature was cooled to 15°C to obtain the protective colloidal base liquid.

[0058] While maintaining the system temperature at 15℃, 80g of mineral-derived potassium fulvicate with a dry basis content of 55.0wt% was added to the protective colloidal base liquid for shear dispersion to obtain a dispersion.

[0059] 5g of matrine with a purity of 99.0wt% and 20g of amino oligosaccharide with a number average molecular weight of 2000Da were dissolved in the second part of deionized water, and the pH value was adjusted to 5.2 by adding 0.10mol / L citric acid solution to obtain a weakly acidic solution.

[0060] A weakly acidic solution was added dropwise to the dispersion at a rate of 15 mL / min / kg to obtain the drug-loaded solution.

[0061] While maintaining the system temperature at 15℃, shear stirring was started and the stirring speed was set to 2400 rpm. 150 g of potassium silicate aqueous solution with a modulus of 2.8 and a solid content of 40.0 wt% was slowly pumped into the system at a pumping rate of 1.5% / min of the total mass volume for shear blending. After degassing, silicate sol was obtained.

[0062] Preparation Example 3:

[0063] This preparation example provides a method for preparing silicate sol, including the following steps:

[0064] 637g of deionized water was divided into two parts with a volume ratio of 9:1. The first part of deionized water was added to the reactor and heated to 90°C. 45g of polyvinyl alcohol with an average degree of polymerization of 1800 and a degree of alcoholysis of 89.0% was added and stirred to dissolve. The cooling rate was controlled at 3.5°C / min by jacket temperature control and the temperature was cooled to 17°C to obtain the protective colloidal base liquid.

[0065] While maintaining the system temperature at 17℃, 100g of mineral-derived potassium fulvicate with a dry basis content of 60.0wt% was added to the protective colloidal base liquid for shear dispersion to obtain a dispersion.

[0066] 8g of matrine with a purity of 99.5wt% and 30g of amino oligosaccharide with a number average molecular weight of 3000Da were dissolved in the second part of deionized water, and the pH value was adjusted to 5.5 by adding 0.15mol / L citric acid solution to obtain a weakly acidic solution.

[0067] A weakly acidic solution was added dropwise to the dispersion at a rate of 20 mL / min / kg to obtain a drug-loaded solution. While maintaining the system temperature at 17°C, shear stirring was started and the stirring speed was set to 2800 rpm. 180 g of potassium silicate aqueous solution with a modulus of 3.0 and a solid content of 42.0 wt% was slowly pumped into the system at a pumping rate of 2.5% / min of the total mass volume for shear blending. After degassing, silicate sol was obtained.

[0068] Preparation Example 4:

[0069] This preparation example provides a pretreatment method for ammonium bicarbonate, including the following steps:

[0070] Ammonium bicarbonate powder with a purity of 99.0 wt% was placed in a fluidized bed dryer, the operating temperature of the equipment was set, and it was dried at 30℃ for 10 minutes. After discharge, it was vacuum-sealed in aluminum foil bags for later use.

[0071] Preparation Example 5:

[0072] This preparation example provides a pretreatment method for ammonium bicarbonate, including the following steps:

[0073] Ammonium bicarbonate powder with a purity of 99.5 wt% was placed in a fluidized bed dryer, the operating temperature of the equipment was set, and it was dried at 32℃ for 12 minutes. After discharge, it was vacuum-sealed in aluminum foil bags for later use.

[0074] Preparation Example 6:

[0075] This preparation example provides a pretreatment method for ammonium bicarbonate, including the following steps:

[0076] Ammonium bicarbonate powder with a purity of 99.9 wt% was placed in a fluidized bed dryer, the operating temperature of the equipment was set, and it was dried at 35℃ for 15 minutes. After discharge, it was vacuum-sealed in aluminum foil bags for later use.

[0077] Example 1:

[0078] See attached document Figure 1 This embodiment provides an ecological control method for diseases and pests in fruit tree seedling cultivation, including the following steps:

[0079] Weigh 1000g of the silicate sol prepared in Preparation Example 1 and mix it with 4000g of water at 12°C to prepare a diluted solution.

[0080] Before application, weigh 20g of ammonium bicarbonate prepared in Preparation Example 4 and add it to the diluent and stir evenly to obtain a mixed solution.

[0081] Starting from the time interval after adding ammonium bicarbonate, apply the mixture to the rhizosphere of the fruit tree seedlings within 35 minutes. The specific application steps are as follows:

[0082] Using a spraying device equipped with an injection probe, insert the probe 5 cm deep into the substrate around the fruit tree seedlings, and inject the mixed solution at a pump volume of 30 mL per tree under an injection pressure of 0.1 MPa.

[0083] Example 2:

[0084] This embodiment provides an ecological control method for diseases and pests in fruit tree seedling cultivation, including the following steps:

[0085] Weigh 1000g of the silicate sol prepared in Preparation Example 2 and mix it with 8000g of water at 15°C to prepare a diluted solution.

[0086] Before application, weigh 30g of ammonium bicarbonate prepared in Preparation Example 5 and add it to the diluent and stir evenly to obtain a mixed solution;

[0087] Starting from the time of adding ammonium bicarbonate, the time interval should be controlled within 25 minutes. Apply the mixture to the rhizosphere of the fruit tree seedlings. The specific application steps are as follows:

[0088] Using a spraying device equipped with an injection probe, insert the probe 10 cm deep into the substrate around the fruit tree seedlings, and inject the mixed solution at a pump volume of 45 mL per tree under an injection pressure of 0.15 MPa.

[0089] Example 3:

[0090] This embodiment provides an ecological control method for diseases and pests in fruit tree seedling cultivation, including the following steps:

[0091] Weigh 1000g of the silicate sol prepared in Preparation Example 3 and mix it with 12000g of water at 18°C ​​to obtain a diluted solution.

[0092] Before application, weigh 40g of ammonium bicarbonate prepared in Preparation Example 6 and add it to the diluent and stir evenly to obtain a mixed solution.

[0093] Starting from the time of adding ammonium bicarbonate, the time interval should be controlled within 15 minutes. Apply the mixture to the rhizosphere of the fruit tree seedlings. The specific application steps are as follows:

[0094] Immerse the roots of the fruit tree seedlings below the surface of the mixed solution for 8 seconds, then lift them up to form a 2.0 mm thick layer of the mixed solution on the root surface before planting.

[0095] Example 4:

[0096] This embodiment provides an ecological control method for diseases and pests in fruit tree seedling cultivation, including the following steps:

[0097] Weigh 1000g of the silicate sol prepared in Preparation Example 2 and mix it with 8000g of water at 15°C to prepare a diluted solution.

[0098] Before application, weigh 30g of ammonium bicarbonate prepared in Preparation Example 5 and add it to the diluent and stir evenly to obtain a mixed solution;

[0099] Starting from the time of adding ammonium bicarbonate, the time interval should be controlled within 25 minutes. Apply the mixture to the rhizosphere of the fruit tree seedlings. The specific application steps are as follows:

[0100] Immerse the roots of the fruit tree seedlings below the surface of the mixed solution for 3 seconds, then lift them up so that the mixed solution forms a 0.5 mm thick layer on the root surface before planting.

[0101] Example 5:

[0102] This embodiment provides an ecological control method for diseases and pests in fruit tree seedling cultivation, including the following steps:

[0103] Weigh 1000g of the silicate sol prepared in Preparation Example 3 and mix it with 12000g of water at 18°C ​​to obtain a diluted solution.

[0104] Before application, weigh 40g of ammonium bicarbonate prepared in Example 6 and add it to the diluent, stirring until homogeneous to obtain a mixture. Starting from the addition of ammonium bicarbonate, time intervals should be controlled within 15 minutes. Apply the mixture to the rhizosphere of the fruit tree seedlings. The specific application steps are as follows:

[0105] Using a spraying device equipped with an injection probe, insert the probe into the substrate around the fruit tree seedlings to a depth of 15cm, and inject the mixed solution at a pump volume of 60mL per tree under an injection pressure of 0.2MPa.

[0106] Comparative Example 1:

[0107] Compared with Example 2, the difference is that ammonium bicarbonate was not added on-site as an independent component. Instead, ammonium bicarbonate was directly added to the mixture and sealed during the preparation of the silicate sol. When applying on-site, it was only diluted with water. Everything else was the same.

[0108] Comparative Example 2:

[0109] The difference from Example 2 is that ammonium bicarbonate was not added before application; otherwise, they are the same.

[0110] Comparative Example 3:

[0111] Compared with Example 2, the difference is that polyvinyl alcohol and potassium humate were not added in the preparation of silicate sol, and they were replaced with deionized water in equal mass, while the rest were the same.

[0112] Comparative Example 4:

[0113] Compared with Example 2, the difference is that the system control temperature during the preparation of silicate sol and the water temperature for on-site dilution were both adjusted to room temperature of 25°C, while the rest were the same.

[0114] Comparative Example 5:

[0115] Compared with Example 2, the difference is that ammonium bicarbonate is replaced by conventional urea powder, while the rest are the same.

[0116] Test Example 1:

[0117] Weigh 500g of each of the first component samples obtained during the preparation process of each embodiment and comparative example, place them in a transparent wide-mouth glass bottle, seal them, and transfer them to a constant temperature and light-proof incubator set at 25°C for storage and static incubation. Observe and record the time when macroscopic phase separation, precipitation, or irreversible flocculation occurs in the samples to evaluate the system's room temperature storage stability. If no such phenomenon occurs after more than 180 days, the observation is terminated and recorded as greater than 180 days.

[0118] The mixing process was carried out according to the on-site preparation steps and water temperature parameters set in each embodiment and comparative example. The apparent viscosity of the mixed system was continuously monitored using an MCR302 rotational rheometer. The test employed a coaxial cylindrical measuring system, with a constant shear rate of 10 s⁻¹. -1 The ambient temperature during testing was kept consistent with the dilution water temperature set for each group.

[0119] Start timing from the point where mixing is complete and record the rheological curve. Record the point at which the apparent viscosity of the system suddenly increases, i.e., the viscosity reaches 50 times the initial viscosity, as the operating window of the system.

[0120] Table 1. Results of the formulation storage stability and operating window test

[0121] Group Stability at room temperature (days) Operation window period (min) Example 1 ＞180 36.4 Example 2 ＞180 27.1 Example 3 ＞180 15.8 Example 4 ＞180 28.3 Example 5 ＞180 16.5 Comparative Example 1 2.3 Hardened lumps appeared 1.2 Comparative Example 3 Flocculation occurs immediately during the preparation process. Unable to test Comparative Example 4 ＞180 4.7

[0122] in conclusion:

[0123] According to the data in Table 1, in Comparative Example 3, without polyvinyl alcohol and potassium humate, the system underwent instantaneous flocculation during the preparation stage. This is because the potassium silicate aqueous solution is highly alkaline, and when it comes into direct contact with the weakly acidic system and free alkaloids, electrostatic neutralization and salting-out effects occur, leading to rapid precipitation of silica gel. Examples 1-5 introduced macromolecular polymers to form protective colloids. Utilizing the steric hindrance effect of the long polymer chains and the surface adsorption of potassium humate, a physical isolation layer was constructed between the strongly alkaline silicate and the alkaloids, altering the kinetic state of the system. This allowed the multi-component suspension to maintain a metastable colloidal structure, with a room temperature storage stability exceeding 180 days.

[0124] In Comparative Example 1, ammonium bicarbonate was pre-mixed into the sol base solution, and the sample hardened and agglomerated within 2.3 days. Ammonium bicarbonate undergoes slight decomposition at room temperature, releasing ammonia and carbon dioxide, causing local pH fluctuations in the system. This disrupts the charge balance of the silicate sol, leading to premature cross-linking and curing under thermodynamic influences, resulting in the loss of rheological properties. Isolating the heat-sensitive gas-generating agent as a separate component and adding it at the on-site stage is a necessary process design to maintain the long-term storage and transportation stability of the main agent.

[0125] The comparison between Examples 1 and Comparative Example 4 reflects the effect of system temperature on the crosslinking kinetics. Comparative Example 4, operated at room temperature (25°C), experienced a sudden change in the apparent viscosity of the mixture within 4.7 minutes, resulting in the fluid losing its pumping and coating capabilities. This timeframe is insufficient for field operations in conventional fruit tree seedling cultivation. Examples 1–5, operating within a water temperature range of 12°C–18°C, suppressed the decomposition rate of ammonium bicarbonate by lowering the initial thermodynamic temperature of the dispersion medium, slowing the decrease in system pH, and thus delaying the critical phase transition point of silicate from sol to gel. This low-temperature process control allows the system to maintain a flow state for 15–35 minutes, ensuring the mixture can penetrate smoothly into the rhizosphere soil layer through the injection probe or form a uniform adhesion layer on the root surface, subsequently relying on the soil's background temperature to drive the in-situ solidification reaction.

[0126] Combined with appendix Figure 2 This further clarifies the rheological operating window of the system. Figure 2The monitoring curves showing the change in apparent viscosity of the mixture over time are presented. In Comparative Example 4, under ambient temperature (25°C) conditions, the viscosity curve of the system showed a steep increase at 4.7 min, indicating that the silicate rapidly reached the critical point of phase transition, and the fluid lost its pumping capability. In Example 2, under cold water (15°C) conditions, the system viscosity remained at a low and flat level of approximately 100 mPa·s for the first 25 min after mixing, until the curve showed a sudden increase at 27.1 min. This low viscosity maintenance range provided the necessary operating time for field equipment to penetrate the soil layer or for root dipping to form a film, demonstrating the practical role of low-temperature control and foaming delay mechanisms in ensuring the continuity of construction operations.

[0127] Test Example 2:

[0128] Following the operating steps of the examples and comparative examples, the potted substrate with the mixed solution applied or the seedlings that had been dipped were transferred into an artificial climate chamber. The ambient temperature was set at 25°C and the relative humidity at 65%, and the plants were left to stand for 48 hours to simulate the real field planting environment, allowing the injected system to complete the in-situ cross-linking and curing reaction.

[0129] The solidified gel layer on the surface of the seedling roots was peeled off, and soil aggregates containing a gel network were collected from the injection site. The samples were rapidly frozen in liquid nitrogen for fixation, then transferred to a vacuum freeze dryer for 24 hours to remove free moisture and maintain the integrity of the microporous structure. The total porosity of the freeze-dried samples was measured using a mercury porosimeter.

[0130] An in-situ air permeability testing device was constructed by sealing the bottom of cultivation pots containing seedlings from each group. A photoelectrode dissolved oxygen sensor probe was pre-embedded 3 cm from the center of the main root system. A standard oxygen gas of a set concentration was continuously introduced into the substrate surface, and the oxygen mass flux data in the rhizosphere region were recorded over 24 hours to assess the physical impact of the gel layer on the substrate gas exchange process.

[0131] Table 2. Microscopic physicochemical structure and air permeability test results of the cured gel

[0132] Group In-situ cured gel porosity (%) <![CDATA[Rhizosphere oxygen mass transfer flux (mg / (m 2 ·h))]]> Example 1 46.3 19.4 Example 2 52.8 23.7 Example 3 63.1 28.5 Example 4 48.2 21.1 Example 5 59.7 27.2 Comparative Example 2 5.4 3.8 Comparative Example 5 6.9 4.2

[0133] in conclusion:

[0134] According to the data in Table 2, the gel porosity of treatment groups 1-5 ranged from 46.3% to 63.1%, and the rhizosphere oxygen mass transfer flux remained between 19.4 and 28.5 mg / (m²). 2 •h) interval. After the mixture is injected into the soil or attached to the root system and enters the natural environment, the rise in ambient background temperature relieves the low-temperature inhibition effect of the solution preparation stage.

[0135] Ammonium bicarbonate in the system undergoes thermodynamic decomposition, releasing carbon dioxide and ammonia. These gas molecules form bubble nuclei within the system and expand. At this time, silicate undergoes a phase transition reaction from sol to gel, driven by a decrease in pH. The formation rate of the silicate three-dimensional cross-linked network is coupled with the gas escape rate, and the pores are solidified and retained in the gel matrix, constructing an interconnected porous network structure.

[0136] In Comparative Example 2, without the addition of ammonium bicarbonate, the porosity was only 5.4%, and the rhizosphere oxygen mass transfer flux decreased to 3.8 mg / (m³). 2 •h). The system undergoes conventional silicate cross-linking and coagulation, resulting in a dense and non-porous gel layer. This dense structure directly blocks the capillary diameters and macropore channels between soil particles, forming a continuous physical barrier layer between the root surface and the substrate.

[0137] The lack of permeable micropores prevents effective atmospheric diffusion and heat / mass exchange of oxygen. Comparative Example 5, using conventional urea instead of ammonium bicarbonate, yielded similar results to Comparative Example 2. Under these conditions, urea did not undergo gas evolution, indicating a lack of gas nucleation sources within the system, and the gel solidification path reverted to the conventional dense film-forming process. The introduction of the foaming mechanism solves the problem of rhizosphere microenvironment hypoxia caused by the inorganic gel barrier sealing the root system, ensuring the gas transport channels required for normal plant physiological respiration.

[0138] Test Example 3:

[0139] Prepare a standard cylindrical transparent acrylic cultivation container with an inner diameter of 30cm and a height of 40cm. Fill the container with naturally air-dried and sieved loam, and use a layer-by-layer compaction method to control the soil bulk density of each layer to be consistent to 1.2g / cm³. 3 The background moisture content of the matrix was measured and adjusted to a relative moisture content of 60%.

[0140] Following the depth, pressure, and volume parameters set in Examples 1, 2, and 5, an application device equipped with a pressure regulating valve and an injection probe with graduation markings was inserted downwards along the central axis of the container to the set depth, and the injection was initiated to pump the mixture into the soil. After application, the container was placed in a 25°C environment and allowed to stand for 24 hours to allow the system to fully cross-link and solidify.

[0141] Longitudinal profile excavation was carried out along the injection axis, and vernier calipers were used to measure the maximum lateral encapsulation radius and maximum longitudinal penetration depth of the solidified gel in the soil.

[0142] Soil samples were collected at three vertical depths (0–5 cm, 5–10 cm, and 10–15 cm) using a ring cutter at a horizontal distance of 2 cm from the main injection axis. The soil samples were air-dried, pulverized, and the effective components were extracted using ultrasonic extraction. The absolute content of matrine in each soil layer sample was determined by high-performance liquid chromatography.

[0143] Table 3. Spatial distribution of pesticide application in the rhizosphere and results of pesticide penetration test.

[0144] Group Maximum lateral wrapping radius (cm) Maximum longitudinal penetration depth (cm) Matrine content (mg / kg) in the 0-5cm soil layer Matrine content (mg / kg) in soil layer 5-10cm Matrine content (mg / kg) in soil layer 10-15cm Example 1 4.1 7.6 14.2 2.3 0.2 Example 2 6.7 13.8 8.5 16.1 4.8 Example 5 9.3 18.5 3.1 10.4 19.7

[0145] in conclusion:

[0146] According to the data in Table 3, different combinations of injection parameters achieved spatially targeted distribution of the drug in the matrix. In Example 1, 30 mL of the mixture was injected at a depth of 5 cm and a pressure of 0.1 MPa. The gel was mainly concentrated in the 0-5 cm surface layer, with a matrine content of 14.2 mg / kg, and the downward penetration depth was limited. With the increase of injection depth, pressure, and pump volume, in Example 5, when 60 mL of the system was applied at a depth of 15 cm, the maximum lateral encapsulation radius expanded to 9.3 cm, and the longitudinal penetration depth reached 18.5 cm. The active pharmaceutical ingredient transferred to deeper layers, with a matrine content of 19.7 mg / kg in the 10-15 cm soil layer, and distribution also observed in the 5-10 cm soil layer, while the distribution in the 0-5 cm surface layer decreased.

[0147] Fluid diffusion in the porous matrix is ​​controlled by initial dynamics and rheological properties. The depth of the injection probe determines the physical location of the jet center, and the set pump pressure is used to overcome the capillary resistance of the soil. Low-temperature control during the operating window keeps the silicate sol in a low apparent viscosity state, preventing phase transition and thickening during the pore penetration stage.

[0148] Driven by pressure, the fluid permeates radially and vertically outwards through the pores of the matrix. As the fluid's kinetic energy dissipates with resistance and a curing reaction is triggered by ambient temperature rise, the resulting porous gel network traps and locks matrine in situ. By adjusting the injection pressure, depth, and dosage per plant, the three-dimensional construction scale of the gel barrier in the soil can be controlled, adapting to the shallow or deep root system configurations of fruit tree seedlings of different planting ages, and providing a matching physical isolation layer.

[0149] Test Example 4:

[0150] Open-field plots with a three-year history of continuous cropping of fruit tree seedlings and a co-infection of root rot and root-knot nematodes were selected as experimental areas. After tilling and leveling, the plots were divided into several independent test plots, with isolation ditches 40cm wide and 30cm deep set between plots to prevent cross-contamination of water and nematodes. The test subject was one-year-old apple rootstock Pingyi sweet tea seedlings.

[0151] The mixture was prepared according to the steps set in each embodiment. Seedlings were either dipped in water at the roots or injected into the rhizosphere after transplanting. The control group was consistent with the corresponding embodiment. A blank control group was set up, in which seedlings were dipped in water only before transplanting. Each group had 50 seedlings, and the treatment was repeated 3 times. After transplanting, routine field watering and weeding management were carried out. No chemical fungicides or nematicides were applied during the experiment.

[0152] The efficacy of control was determined 60 days after transplanting. Rhizosphere soil samples were collected from each plot using a five-point sampling method. Soil nematodes were isolated using the Bellman funnel method, and the number of second-instar larvae of root-knot nematodes was counted under a microscope to calculate the nematode population reduction rate. Seedlings were dug up with soil, roots were washed clean, and disease severity was graded based on the proportion of browning and rotten areas to the total root area. The relative efficacy against root rot was then calculated.

[0153] The actual number of surviving seedlings in each group 60 days after transplanting was counted, and the survival rate was calculated. Newly grown white fibrous root samples were taken, and root activity was determined using the triphenyltetrazolium chloride reduction method. The values ​​were expressed as micrograms of triphenyltetrazolium chloride reduced per gram of fresh root per hour.

[0154] Table 4. Results of Field Biological Control Efficacy and Seedling Growth Indicators Tests

[0155] Group Root-knot nematode population reduction rate (%) Root rot prevention efficacy (%) Seedling survival rate (%) Root activity (μg / g·h) Example 1 76.4 74.1 92.6 143.2 Example 2 83.5 81.2 94.3 151.7 Example 3 88.2 86.4 97.8 168.4 Example 4 78.1 79.6 93.1 146.5 Example 5 85.6 84.3 95.2 162.1 Comparative Example 2 71.5 73.2 56.4 48.3 Comparative Example 3 24.6 21.3 68.1 82.4 Comparative Example 4 54.2 49.7 79.5 105.6 Comparative Example 5 69.8 72.1 58.7 51.2 Blank control group 0.0 0.0 52.3 64.8

[0156] in conclusion:

[0157] According to the data in Table 4, the seedlings treated in Examples 1–5 maintained a high survival rate and root development level in continuously cropped diseased soil, with root rot control efficacy ranging from 74.1% to 86.4%. The in-situ solidified silicate gel constructed a physical isolation barrier with spatial thickness in the seedling rhizosphere. This inorganic gel framework can prevent root-knot nematodes from invading root tissues, while simultaneously cutting off the physical pathway for soil-borne fungal spores and zoospores to contact the root epidermis.

[0158] After matrine and amino oligosaccharides were encapsulated in a cross-linked network, their leaching and loss to the surrounding soil environment was slowed, forming a sustained concentration distribution zone on the root surface and producing a chemobiological control effect against pathogen targets. Potassium humate was released during gel degradation, participating in soil organic matter cycling and stimulating the development of new root tip meristems, as evidenced by the high level of root vigor maintained in the example group.

[0159] Comparative Examples 2 and 5 showed specific disease and insect control data, but their survival rates dropped to 56.4% and 58.7%, respectively, indicating low root vigor. While the low permeability of conventional dense silicate solids did effectively isolate pathogens, it also blocked the rhizosphere oxygen input pathway. Root hypoxia led to anaerobic respiration, and the accumulated ethanol and lactic acid caused tissue metabolic disorders and physiological necrosis. Introducing ammonium bicarbonate decomposition foaming is the core technology for resolving the contradiction between the physical barrier against disease and root respiration.

[0160] The efficacy indicators of Comparative Example 3 decreased. The lack of protective colloids caused premature flocculation during the solution preparation period, resulting in silicates being injected into the soil as macroscopic particle aggregates, unable to form a continuous coating at the microscopic scale that conforms to root morphology. The effective components of the pesticide were not retained by the gel and rapidly leached into the deeper soil layers with irrigation water, thus losing their rhizosphere defense capabilities.

[0161] Comparative Example 4, which used room-temperature solution preparation, shortened the fluid operation window. The mixture underwent partial cross-linking and thickening during injection or application diffusion, resulting in gaps and defects in the soil film formation. Pathogens could then infect the soil through unsealed areas, leading to a moderate level of control efficacy. The lack of proper formulation and process control in each group ultimately resulted in deterioration in field application effectiveness.

[0162] Appendix Figure 3 This study comprehensively reflects the correlation between the air permeability of the solidified gel and the final seedling survival rate in different treatment groups. The bar chart represents the rhizosphere oxygen mass transfer flux of different treatment groups, and the line graph represents the corresponding field survival rate. In Examples 1-3, due to the introduction of a kinetic foaming mechanism, the rhizosphere oxygen mass transfer flux remained at 19.4 mg / (m³). 2 Above 1000 h, the corresponding seedling survival rates all exceeded 92.0%, showing a clear positive synergistic trend between the two sets of data. In Comparative Examples 2 and 5, due to the lack of an effective gas nucleation source, the oxygen mass transfer flux decreased to 5.0 mg / (m³). 2 Below h), the survival rate curve simultaneously drops below 60.0%. The chart data visually confirms that the porous gel network constructed in this invention maintains the oxygen transport conditions required for plant root respiration while maintaining physical isolation against disease, thus solving the technical problem of conventional inorganic membranes blocking gas and causing root rot.

Claims

1. An ecological control method for diseases and pests in fruit tree seedling cultivation, characterized in that, Includes the following steps: A protective colloidal base solution was prepared by mixing and dissolving polyvinyl alcohol with water. Potassium humate, matrine, and amino oligosaccharide were added to the protective colloidal base solution to prepare a drug-loaded solution. A potassium silicate aqueous solution was added to the drug-carrying solution and mixed to obtain a silicate sol; The silicate sol was mixed with water, and ammonium bicarbonate was added to prepare a mixture. The mixture is applied to the rhizosphere of the fruit tree seedlings.

2. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, The raw material composition of the silicate sol, by mass percentage, is as follows: Potassium silicate aqueous solution 12.0wt%-18.0wt%; Polyvinyl alcohol 2.0wt%-4.5wt%; Potassium humate 6.0wt%-10.0wt%; Amino oligosaccharides 1.5wt%-3.0wt%; Matrine 0.3wt%-0.8wt%; The remainder is deionized water; The sum of the mass percentages of all components is 100 wt%. The amount of ammonium bicarbonate added is 2.0wt%-4.0wt% of the total mass of the silicate sol.

3. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, In the steps of adding potassium humate, matrine and amino oligosaccharide to the protective colloidal base solution to prepare the drug-loaded solution, and in the steps of adding potassium silicate aqueous solution to the drug-loaded solution for blending to prepare silicate sol, the system temperature is controlled at 13℃~17℃.

4. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, The specific steps for preparing the drug-loaded solution by adding potassium humate, matrine, and amino oligosaccharide to the protective colloidal base solution are as follows: The potassium humate was added to the protective colloidal base liquid and sheared and dispersed to obtain a dispersion. The matrine and the amino oligosaccharide were dissolved in water, and the pH was adjusted to between 5.0 and 5.5 by adding citric acid solution dropwise to obtain a weakly acidic solution. The weakly acidic solution is added dropwise to the dispersion to obtain the drug-loaded solution.

5. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, In the step of mixing the silicate sol with water and adding ammonium bicarbonate to obtain a mixed solution, the silicate sol is mixed with water at a temperature of 12°C to 18°C ​​at a mass ratio of 1:4 to 1:

12.

6. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, The time interval between adding ammonium bicarbonate and applying the mixture to the rhizosphere of the fruit tree seedlings should be controlled within 15 to 35 minutes.

7. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, The specific steps for applying the mixture to the rhizosphere of fruit tree seedlings are as follows: Using a spraying device equipped with an injection probe, insert the probe into the substrate around the fruit tree seedlings at a depth of 5cm to 15cm, and inject the mixture at an injection pressure of 0.1MPa to 0.2MPa, with a pump volume of 30mL to 60mL per tree.

8. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, The specific steps for applying the mixture to the rhizosphere of fruit tree seedlings are as follows: The roots of the fruit tree seedlings are immersed in the mixture for 3 to 8 seconds. After immersion, the seedlings are lifted to form a 0.5 mm to 2.0 mm thick layer of the mixture on the root surface before planting.

9. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, Before the step of mixing the silicate sol with water and adding ammonium bicarbonate to obtain a mixture, a pretreatment step of the ammonium bicarbonate is also included: The ammonium bicarbonate was placed in a fluidized bed dryer and dried at 30°C to 35°C for 10 to 15 minutes.

10. The ecological control method for fruit tree seedling diseases and pests according to claim 1, characterized in that, The potassium silicate aqueous solution has a modulus of 2.5 to 3.0 and a solid content of 38.0 wt% to 42.0 wt%.

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