Preparation method and application of lime seedling substrate

Abstract

The invention relates to a preparation method and application of a lime seedling culture substrate. The preparation method of the lime seedling culture substrate comprises the following steps: soaking coco coir in citric acid for 24 hours to obtain coco coir A; carbonizing the carbonized rice husks at 550 DEG C for 30 minutes, and spraying sodium silicate for curing to obtain carbonized rice husks B; premixing the wormcast and the silicon carbide nanoparticles to obtain a biochar mixture; the preparation method comprises the following steps: stirring and fermenting coco coir A, a biochar mixture and carbonized rice husk B until the pH is 6.0 and the EC is 0.4 mS / cm to obtain a fermented material, sterilizing the fermented material through cobalt-60, adding vermiculite, a complex microbial inoculant and a slow-release nutrient, uniformly stirring and mixing at-0.05 MPa, and curing for 48 hours in a darkroom at 25 DEG C. The prepared matrix is used for industrial container seedling culture of lime, and under the conditions that the day temperature is 25 + / -2 DEG C / night temperature is 18 + / -2 DEG C and the illumination is 30000 Lux, the yield of the lime is increased, and the yield of the lime is increased. 60 days after sowing, the seedling rate reaches 92.0%, the root activity is 120 [mu] g TF / g.h, and the seedling raising efficiency and quality are significantly improved.

Description

Technical Field

[0001] The present application relates to the technical field of polymer compounds, and in particular to a method for preparing a sour orange seedling cultivation matrix and its application. Background Art

[0002] As a major global cash crop, the healthy and sustainable development of the citrus industry is closely linked to the production of high-quality seedlings. Seedling substrates are the core vehicle for factory-grown seedlings, and their physical and chemical properties directly influence seed germination, root development, and seedling resistance. Traditional substrates primarily rely on materials such as peat, vermiculite, and perlite. Peat is widely recognized for its rich humic acid and water-holding properties, but it is a non-renewable resource, and overexploitation can lead to ecological damage and carbon sink loss. Rockwool, while breathable, is non-degradable and causes secondary pollution. Inorganic substrates such as vermiculite and perlite lack nutrient-release properties, requiring reliance on external fertilizers and prone to seedling burn and salinization. Citrus crops, particularly sour orange varieties, are extremely sensitive to substrate pH, EC, and air permeability. Existing formulations are mostly designed for general-purpose fruit seedlings and fail to consider the sour orange's weak root system and need for a high-oxygen environment. For example, while peat-based formulations are suitable for common citrus, their high water retention can easily lead to root rot in sour oranges. Substrate disinfection often involves steam or chemical fumigation, which can kill beneficial microorganisms. The fermentation process is long and has poor ingredient stability. With the increasing adoption of sustainable development, global research is shifting to environmentally friendly alternatives, such as coconut coir, vermicompost, and agricultural waste, aiming to balance functionality with environmental friendliness. Cultivating earthworms with cow dung produces vermicompost rich in organic matter and slow-release nitrogen. While adding peat moss can improve seedling emergence, peat residue is still unavoidable. Combining coconut husks with sugarcane bagasse can lead to compaction in a single organic substrate, necessitating the addition of quartz sand to improve air permeability, which can dilute nutrients. As a high-value variety, sour oranges are susceptible to oxygen deficiency during seedling cultivation and have a higher requirement for trace elements (iron and zinc) than common citrus. Deficiencies can lead to chlorosis and susceptibility to damping-off disease. Therefore, substrates containing probiotics are essential for pathogen suppression. Environmental impacts must also be considered. Seedling cultivation should avoid excessive reliance on chemical additives, such as ferrous sulfate and urea, as long-term use can exacerbate soil acidification.

[0003] In summary, a new method for preparing and applying a sour orange seedling culture medium is urgently needed to be developed on the market. Summary of the Invention

[0004] The present application provides a method for preparing a sour orange seedling culture medium and its application, so as to solve the problems raised in the above-mentioned background technology.

[0005] To solve the above technical problems, the present application discloses a method for preparing a lime seedling cultivation substrate, comprising the following steps: Step S1, soaking coconut husk in a citric acid solution at room temperature to obtain coconut husk A, carbonizing carbonized rice husk, cooling and spraying with a sodium silicate solution to solidify it to obtain carbonized rice husk B, premixing earthworm castings with silicon carbide nanoparticles, and stirring to obtain an earthworm castings biochar mixture; Step S2, stirring and fermenting the coconut bran A, the earthworm castings biochar mixture and the carbonized rice husk B to obtain a fermentation material; Step S3: sterilize the fermented material by radiation and cool it, add vermiculite, compound bacterial agent and slow-release nutrients, stir it, and mature it to obtain the sour orange seedling medium.

[0006] Furthermore, the method comprises premixing earthworm castings and silicon carbide nanoparticles in a weight ratio of 25-28:7-8, and stirring at 30-40 rpm for 15-20 minutes to obtain an earthworm castings biochar mixture.

[0007] Furthermore, the fermentation material is sterilized by radiation, cooled to 28-30° C., 11-15 parts of vermiculite, 4-5 parts of composite bacterial agent, and 3-4 parts of slow-release nutrients are added, and stirred at 45-50 rpm for 25-30 minutes at -0.06 to -0.05 MPa.

[0008] Furthermore, the carbonized rice husk is carbonized at 550-600° C. for 25-30 minutes in anoxic condition, and after cooling, it is sprayed with a sodium silicate solution at a spraying amount of 10 mL / 100 g, and allowed to stand and solidify for 10-12 hours to obtain carbonized rice husk B.

[0009] Furthermore, the soil was matured at 25-26° C. in a dark room for 48 hours, and the pile was turned over once every 12 hours with a turning height of 1 m to obtain a sour orange seedling medium.

[0010] Furthermore, the preparation method of the slow-release nutrient includes: granulating 26.1 parts of urea, 13.1 parts of ammonium dihydrogen phosphate, and 16.7 parts of potassium chloride by weight, spraying 10 parts of polyglutamic acid solution, granulating at 45°C for 5 hours, and drying at 80°C for 1 hour to obtain a core material; dissolving 15 parts of polylactic acid in 40 parts of dichloromethane, adding 2 parts of nano-silicon dioxide and 1 part of magnesium stearate, and ultrasonically dispersing to obtain a coating liquid; preheating the core material to 40°C, spraying it in a fluidized bed at 8 mL / min, with an atomization pressure of 0.15 MPa, and curing it at 50°C for 2 hours.

[0011] Furthermore, the preparation method of the composite bacterial agent includes: inoculating Bacillus subtilis CGMCC 1.1086 seed liquid into the culture medium, aerating the culture medium at a ratio of 1:1.0 vvm, and fermenting the culture medium at 250 rpm for 36 hours; mixing the Bacillus subtilis fermentation liquid with Rhizophagus irregularis DAOM 197198 spore powder; adding skimmed milk powder, trehalose, and glycerol; spray drying the culture medium; pre-freezing the culture medium to -40°C; and vacuum drying the culture medium for 12 hours.

[0012] Furthermore, the seed liquid of Bacillus subtilis CGMCC 1.1086 was inoculated into a culture medium containing 20 g / L sucrose and 15 g / L soybean meal.

[0013] In a second aspect, the present application relates to an application of the method for preparing a sour orange seedling substrate, wherein three sour orange seeds are sown in a 32-hole tray, and each hole is covered with 1 cm of soil.

[0014] Furthermore, the day temperature was controlled at 25°C / night temperature at 18°C, the light intensity was 30,000 Lux, and the humidity was 60%, and the gravimetric method was used to maintain the water holding capacity of the substrate at 70%.

[0015] Compared with the prior art, the present application provides a method for preparing a lime seedling cultivation substrate and its application, which has the following beneficial effects: 1. This application establishes a highly stable porous structure to solve the problem of water retention and ventilation imbalance. The earthworm castings involved are pre-mixed with silicon carbide nanoparticles and synergized with sodium silicate-cured rice husks. The synergistic pore-forming effect of carbonized rice husk silicon curing and earthworm casting nano-modification achieves a reduction in bulk density and an increase in total porosity, reducing root hypoxia or dehydration. 2. The composite bacterial agent involved in this application is colonized on the nano-silicon carbide carrier, the bacterial count is increased, the microbial activity is enhanced, the fermentation time is reduced, and the EC value is stable; 3. The polylactic acid coated slow-release nutrient involved in this application is coupled with the nutrient slow-release of the polylactic acid coated nutrient by the vermiculite layered structure. When vermiculite is present, the effective phosphorus release period of the slow-release nutrient is extended, the release rate of alkaline nitrogen / effective phosphorus / fast-acting potassium is reduced, the seedling rate is increased, and the root activity is improved; 4. The factory-based seedling cultivation cycle involved in this application is shorter, which improves efficiency and comprehensively optimizes plant height, stem thickness and root length. DETAILED DESCRIPTION

[0016] The preferred embodiments of the present application are described below. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0017] In addition, in this application, descriptions such as "first" and "second" are only used for descriptive purposes and do not specifically refer to the order or ranking, nor are they used to limit this application. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions and technical features between the various embodiments can be combined with each other, but this must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0018] Unless otherwise specified, the examples and comparative examples are parallel experiments with the same components, component contents, preparation steps, and preparation parameters. The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are analytical reagents (AR) unless otherwise specified, which were purchased from commercial channels.

[0019] The coconut coir was LBYM-3 (block form) from Hainan Lvbao Biotechnology, the carbonized rice husk was JHK-550 (granular form) from Henan Jinhe Carbon Industry, the earthworm cast was QG-OR01 (powder form) from Suqiuguan Bioengineering, the silicon carbide nanoparticles were XT-C-2 from Shanghai Xiangtian Nanomaterials Co., Ltd., the sodium silicate solution was JSM-40 (liquid form) from Sichuan Jinshan Chemical, the vermiculite was JS-ZS2 (expanded grade) from Tangshan Jinshi Minerals, Hebei Province, the urea was food-grade granules (N ≥ 46.4%) from Hubei Yihua Group, the ammonium dihydrogen phosphate was AR-Grade (P2O5 ≥ 61%) from Guizhou Wengfu Group, the polyglutamic acid solution was XK-PGA30 (fermentation method) from Nanjing Xuankai Biological, and the polylactic acid (PLA) was REVODE from Zhejiang Hisun Biological. The ingredients used in the fermentation were: 190 type (injection molding grade), XAS-200 type (hydrophobic type) nanosilica from Zhejiang Xin'an Chemical, CGMCC1.1086 type Bacillus subtilis from China General Microorganisms Collection, DAOM 197198 type spore powder from the Canadian Fungal Collection, Anchor™ SMP-20 type (industrial grade) skimmed milk powder from Fonterra (New Zealand), TREHA™ LQ type (crystalline type) from Hayashibara Biotechnology (Japan), Wilmar G99 type (pharmaceutical grade) glycerol from Wilmar International (Malaysia), food-grade monohydrate citric acid solution from Shandong Lemon Biochemical Co., Ltd. (model: LM-88), and fermentation medium components: LP0042 type peptone from OXOID (UK), AB0140 type beef extract from Beijing Aoboxing, and premium white granulated sugar from Nanning Sugar (compliant with GB / T 317). Example 1

[0020] This embodiment discloses a method for preparing a sour orange seedling cultivation substrate, which comprises the following steps in parts by weight: Step 1, coconut bran is soaked in 0.5% (w / v) citric acid solution at room temperature for 24 hours to obtain coconut bran A, 18 parts of carbonized rice husk are carbonized at 550°C for 30 minutes in anoxic condition, and after cooling, sodium silicate solution is sprayed at a spray rate of 10 mL / 100 g, and carbonized rice husk is allowed to stand and solidify for 12 hours to obtain carbonized rice husk B, 25 parts of vermicompost are premixed with 7 parts of silicon carbide nanoparticles, and stirred at 30 rpm for 20 minutes to obtain a vermicompost biochar mixture; Step 2: The coconut bran A, the earthworm castings biochar mixture, and the carbonized rice husk B were put into a double-layer spiral mixer, and fermented at 45°C, 60% humidity, and 0.3 m³ / min at a low speed of 15 rpm for 72 hours. The pH and EC values ​​were sampled every 12 hours. When the pH was 6.0 and the EC value was 0.4 mS / cm, the fermentation was stopped to obtain a fermented material. Step 3: sterilize the fermented material by cobalt-60 radiation, cool it to 30°C, add 13 parts of vermiculite, 4 parts of composite bacterial agent and 3 parts of slow-release nutrients, stir it at 45 rpm for 30 minutes at -0.05 MPa, mature it at 25°C in a dark room, turn it over once every 12 hours, turn it over to a height of 1 m, and mature it for 48 hours to prepare the sour orange seedling substrate.

[0021] The preparation method of the slow-release nutrient comprises: adding 26.1 parts of urea, 13.1 parts of ammonium dihydrogen phosphate and 16.7 parts of potassium chloride by weight into a high-speed vortex granulator, spraying 10 parts of polyglutamic acid solution, granulating at 45°C for 5 hours, and drying at 80°C for 1 hour to obtain a core substance; dissolving 15 parts of polylactic acid in 40 parts of dichloromethane, stirring at 35°C for 2 hours, adding 2 parts of nano-silicon dioxide and 1 part of magnesium stearate, and ultrasonically dispersing for 30 minutes to obtain a coating liquid; preheating the core substance to 40°C, adding it into a fluidized bed with an air inlet temperature of 50°C, spraying it with the coating liquid at a rate of 8 mL / min, an atomization pressure of 0.15 MPa, and a fluidizing wind speed of 1.2 m³ / min, and curing it with hot air at 50°C for 2 hours to obtain the slow-release nutrient.

[0022] The preparation method of the composite functional bacterial agent comprises the following steps: inoculating Bacillus subtilis CGMCC 1.1086 into a culture medium containing 10 g / L of peptone, 5 g / L of beef extract and 5 g / L of NaCl at a pH of 7.2 with an inoculation amount of 2% (v / v), culturing at 37°C and 220 rpm for 12 hours to obtain a seed solution; inoculating the seed solution into a culture medium containing 0.5 g / L of sucrose, 15 g / L of soybean meal powder, 2 g / L of K2HPO4 and 0.5 g / L of MgSO4 for fermentation with an inoculation amount of 5% (v / v), an aeration ratio of 1:1.0 vvm, a stirring speed of 250 rpm, and a fermentation time of 36 hours to obtain a Bacillus subtilis fermentation liquid; and when the residual sugar level drops to 5 g / L during fermentation, adding 300 g / L of sucrose solution; and mixing the Bacillus subtilis fermentation liquid and Rhizophagus irregularis DAOM with each other. The spore powder of 197198 was mixed in a ratio of 4:1 (v / w), and 10% (w / v) skim milk powder, 5% (w / v) trehalose and 3% (v / v) glycerol were added. The mixture was spray-dried with an inlet air temperature of 110°C, an outlet air temperature of 50°C and an atomization pressure of 0.25 MPa. The mixture was pre-frozen to -40°C and vacuum-dried for 12 hours to obtain a composite functional bacterial agent.

[0023] Application Example 1 The orange seedling cultivation matrix prepared by the orange seedling cultivation matrix preparation method was used for factory-scale container cultivation of orange seedlings. Each matrix was placed in a 32-hole tray (hole diameter 5 cm), and three pre-treated (0.1% KMnO4 soaked for 10 min) orange seeds were sown in each hole and covered with 1 cm of soil. The temperature and light conditions were as follows: daytime temperature 25±2°C / nighttime temperature 18±2°C, light intensity 30,000 Lux (12 h / d), and humidity 60%. Water management: water control by gravimetric method (water holding capacity 70%±5%). Example 2

[0024] This embodiment discloses a method for preparing a sour orange seedling cultivation substrate, which comprises the following steps in parts by weight: Step 1, coconut bran is soaked in 0.7% (w / v) citric acid solution at room temperature for 18 hours to obtain coconut bran A, 20 parts of carbonized rice husks are carbonized at 600°C for 25 minutes under anoxic conditions, and after cooling, a sodium silicate solution is sprayed at a spray rate of 10 mL / 100 g, and the mixture is allowed to stand and solidify for 10 hours to obtain carbonized rice husk B, 28 parts of vermicompost and 8 parts of silicon carbide nanoparticles are premixed, and the mixture is stirred at 40 rpm for 15 minutes to obtain a vermicompost biochar mixture; Step 2: The coconut bran A, the earthworm castings biochar mixture, and the carbonized rice husk B were put into a double-layer spiral mixer, and fermented at 50°C, 65% humidity, and 0.35 m³ / min at a low speed of 20 rpm for 60 hours. The pH and EC values ​​were sampled every 12 hours. When the pH was 6.1 and the EC value was 0.42 mS / cm, the fermentation was stopped to obtain a fermented material. Step 3, the fermentation material was sterilized by cobalt-60 radiation, cooled to 28 ° C, 15 parts of vermiculite, 4.5 parts of composite bacterial agent and 3.5 parts of slow-release nutrients were added, stirred at 50 rpm for 25 minutes at -0.06 MPa, matured in a dark room at 26 ° C, turned once every 12 hours, the turning height was 1 m, and the lime seedling substrate was matured for 48 hours. The other contents were consistent with Example 1. Example 3

[0025] This embodiment discloses a method for preparing a sour orange seedling cultivation substrate, which comprises the following steps in parts by weight: Step 1, coconut bran is soaked in 0.5% (w / v) citric acid solution at room temperature for 24 hours to obtain coconut bran A, 18 parts of carbonized rice husk are carbonized at 550°C for 30 minutes in anoxic condition, and after cooling, sodium silicate solution is sprayed at a spray rate of 10 mL / 100 g, and carbonized rice husk is allowed to stand and solidify for 12 hours to obtain carbonized rice husk B, 25 parts of vermicompost are premixed with 7 parts of silicon carbide nanoparticles, and stirred at 30 rpm for 20 minutes to obtain a vermicompost biochar mixture; Step 2: The coconut bran A, the earthworm castings biochar mixture, and the carbonized rice husk B were put into a double-layer spiral mixer, and fermented at 45°C, 60% humidity, and 0.3 m³ / min at a low speed of 15 rpm for 72 hours. The pH and EC values ​​were sampled every 12 hours. When the pH was 6.0 and the EC value was 0.4 mS / cm, the fermentation was stopped to obtain a fermented material. Step 3, the fermentation material was sterilized by cobalt-60 radiation, cooled to 30 ° C, 11 parts of vermiculite, 5 parts of composite bacterial agent and 4 parts of slow-release nutrients were added, stirred at 45 rpm for 30 minutes at -0.05 MPa, matured at 25 ° C in a dark room, turned once every 12 hours, the turning height was 1 m, and the lime seedling substrate was matured for 48 hours. The other contents were consistent with Example 1.

[0026] Comparative Example 1 The difference from Example 1 is that the earthworm castings and biochar mixture is missing, and earthworm castings are used directly. The fermentation material is made of coconut bran A, earthworm castings and carbonized rice husks B. Other aspects are the same.

[0027] Comparative Example 2 The difference from Example 1 is that the vermiculite is missing in equal parts by weight, and the other parts are the same.

[0028] Comparative Example 3 The difference from Example 1 is that the coconut bran A is missing in equal parts by weight, and the fermentation material is obtained by using a mixture of earthworm castings and biochar and carbonized rice husks B. The other parts are the same.

[0029] Comparative Example 4 The difference from Example 1 is that the carbonized rice husk B is missing in equal parts by weight, and the fermentation material is obtained by using a mixture of vermicompost biochar and coconut husk A; the rest are the same.

[0030] Performance Testing Performance testing was conducted on the examples and comparative examples. Physical properties (referring to LY / T 2709-2016 Forestry Industry Standard "Seedling Culture Media") were as follows: Bulk density (g / cm³): calculated by the ring knife method; total porosity (%): calculated by the saturated water holding weight method; and aerated porosity (%): calculated by the tension plate method (pore water content under -10 cm water column suction).

[0031] Water-holding porosity (%): Total porosity - Air-permeable porosity. Large-to-small porosity ratio: Air-permeable porosity / Water-holding porosity. Structural stability (water stability index): Wet the substrate and use a wet sieve method (5 mm mesh) to calculate the proportion of water-stable particles larger than 2 mm. A higher index indicates better stability. Chemical properties: pH: Extraction using a 1:5 (volume ratio) substrate: water, measured with a pH meter (GB / T 7859-2005). EC value (mS / cm): Extraction using a 1:5 (volume ratio) substrate: water, measured with a conductivity meter (GB / T 7870-2010). Organic matter content (%): Potassium dichromate volumetric method (GB / T 9834-1988). Total nitrogen (N, %): Kjeldahl method (NY / T 53-1987). Total phosphorus (P, %): Molybdenum antimony colorimetric method (NY / T 88-1988). Total potassium (K, %): Flame photometry (NY / T 87-1988). Alkali-hydrolyzable nitrogen (mg / kg): Alkaline diffusion method. Available phosphorus (mg / kg): Olsen method (NY / T 1121.7-2006). Available potassium (mg / kg): Ammonium acetate extraction-flame photometry (NY / T 889-2004). Microbiological properties (culture enumeration method): Bacterial count (CFU / g): Beef extract peptone agar medium, dilution spread plate method, incubate at 30°C for 48 hours and enumerate. Fungal count (CFU / g): Martin's (Red Bengal) agar medium (with antibiotics), dilution spread plate method, incubate at 25-28°C for 3-5 days and enumerate. Biological Effect (Pot Test): Test Subject: Citrus rootstock (Poncirus trifoliata) seeds (healthy, plump, and pre-sterilized). Test Method: Each substrate was filled with seedling trays (50 holes) of the same size, with 3 seeds sown per hole. The cells were incubated at 25±2°C and 12 hours of light per day. Ten replicate trays (50 holes total) were used for each substrate. Test Indicators: Germination Potential (%): Number of germinated seeds 15 days after sowing / Total number of seeds × 100%. Germination Rate (%): Number of germinated seeds 30 days after sowing / Total number of seeds × 100%. Seedling Survival Rate (%): Number of healthy seedlings (with two or more true leaves and no diseased or weak seeds) / Number of germinated seeds × 100% at 60 days after sowing. Plant Height (cm): Measured from the substrate surface to the highest point of the seedling at seedling establishment. Stem Diameter (mm): Measured the stem diameter 1 cm below the cotyledons at seedling establishment. Aboveground fresh weight / dry weight (g): Measured at seedling establishment. Root length (cm): Taproot length measured at seedling establishment. Root activity (TTC method) (µg TF / g·h): Determined using the triphenyltetrazolium chloride (TTC) reduction method. Results are shown in Table 1.

[0032] Table 1 Test items unit Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 bulk density g / cm³ 0.16 0.15 0.14 0.22 0.18 0.25 0.17 Total porosity % 74.0 75.0 76.0 68.0 70.0 65.0 72.0 Ventilation porosity % 24.0 25.0 26.0 20.0 22.0 18.0 18.0 Water holding porosity % 50.0 50.0 50.0 48.0 48.0 47.0 54.0 Size pore ratio 0.48 0.50 0.52 0.42 0.46 0.38 0.33 Structural stability (>2mm particles) % 86.0 83.0 85.0 70.0 82.0 75.0 80.0 pH (1:5) 6.0 6.1 6.2 5.8 6.2 5.9 6.0 EC (1:5) mS / cm 0.42 0.40 0.39 0.45 0.38 0.43 0.50 organic matter % 36.0 34.0 35.0 33.0 32.0 30.0 34.0 Total nitrogen (N) % 1.52 1.50 1.48 1.45 1.40 1.42 1.55 <![CDATA[Total Phosphorus (P2O5)]]> % 0.82 0.80 0.78 0.78 0.75 0.76 0.79 <![CDATA[Total potassium (K2O)]]> % 1.22 1.20 1.18 1.18 1.15 1.16 1.19 Alkaline nitrogen mg / kg 185 180 175 170 160 165 190 Available phosphorus (Olsen P) mg / kg 82 80 78 75 70 72 76 Fast-acting potassium mg / kg 153 150 152 145 140 142 148 bacteria <![CDATA[×10 6 CFU / g]]> 48.0 52.0 50.0 40.0 45.0 42.0 47.0 fungi <![CDATA[×10 4 CFU / g]]> 19.1 21.0 19.8 15.0 18.0 16.0 18.5 Germination potential (day 15) % 95.2 94.1 94.8 85.0 90.0 88.0 92.0 Seedling rate (60th day) % 93.5 91.1 92.3 80.0 85.0 82.0 88.0 Plant height cm 18.5 17.5 18.1 15.0 16.0 14.5 16.5 Stem thickness mm 2.52 2.48 2.50 2.20 2.35 2.15 2.40 Fresh weight of aboveground parts g 1.23 1.18 1.21 0.90 1.05 0.80 1.10 Above ground dry weight g 0.26 0.24 0.25 0.18 0.22 0.17 0.23 Root length cm 15.2 14.8 15.0 12.0 13.5 11.5 14.0 Root activity (TTF) µg TF / g·h 122 118 120 90 105 85 110 As can be seen from Table 1, Example 1 has the best comprehensive performance. The lack of the earthworm castings and biochar mixture causes a sudden drop in structural stability, a decrease in the number of microorganisms, and an overall deterioration in biological effects: the seedling rate decreases, the root activity decreases, and the vermiculite has a water-retaining effect. The lack of vermiculite leads to a decrease in water-holding porosity, an imbalance in the ratio of large and small pores, and a significant loss of available nutrients: alkaline nitrogen decreases, available phosphorus decreases, the seedling rate decreases, and the aboveground dry weight decreases. Coconut bran A has a pore-building effect, and the lack of coconut bran leads to an increase in bulk density, a decrease in total porosity, a decrease in root length, and a decrease in seedling rate. Carbonized rice husk B has a ventilation function. The lack of carbonized rice husk B leads to a decrease in ventilation porosity, an increase in EC value, a decrease in plant height, and a decrease in stem diameter.

[0033] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. If these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for preparing a sour orange seedling culture medium, characterized in that: The following steps are involved: Step S1, soaking coconut husk in a citric acid solution at room temperature to obtain coconut husk A, carbonizing carbonized rice husk, cooling and spraying with a sodium silicate solution to solidify it to obtain carbonized rice husk B, premixing earthworm castings with silicon carbide nanoparticles, and stirring to obtain an earthworm castings biochar mixture; Step S2, stirring and fermenting the coconut bran A, the earthworm castings biochar mixture and the carbonized rice husk B to obtain a fermentation material; Step S3: sterilize the fermented material by radiation and cool it, add vermiculite, compound bacterial agent and slow-release nutrients, stir it, and mature it to obtain the sour orange seedling medium.

2. The method for preparing a sour orange seedling culture medium according to claim 1, wherein The method comprises premixing earthworm castings and silicon carbide nanoparticles in a weight ratio of 25-28:7-8, and stirring the mixture at 30-40 rpm for 15-20 minutes to obtain an earthworm castings biochar mixture.

3. The method for preparing a sour orange seedling culture medium according to claim 1, wherein The method comprises, by weight, sterilizing the fermentation material by radiation, cooling to 28-30° C., adding 11-15 parts of vermiculite, 4-5 parts of composite bacterial agent, and 3-4 parts of slow-release nutrients, and stirring at 45-50 rpm for 25-30 minutes at -0.06 to -0.05 MPa.

4. The method for preparing a sour orange seedling culture medium according to claim 1, wherein The carbonized rice husk was carbonized at 550-600° C. under anoxic conditions for 25-30 minutes, and after cooling, a sodium silicate solution was sprayed thereon at a spraying rate of 10 mL / 100 g. The carbonized rice husk was allowed to stand and solidify for 10-12 hours to obtain carbonized rice husk B.

5. The method for preparing a sour orange seedling culture medium according to claim 1, wherein The mixture was matured in a dark room at 25-26°C for 48 hours, and the pile was turned over once every 12 hours to a height of 1m to obtain the sour orange seedling medium.

6. The method for preparing a sour orange seedling culture medium according to claim 1, wherein The preparation method of the slow-release nutrient comprises: granulating 26.1 parts of urea, 13.1 parts of ammonium dihydrogen phosphate, and 16.7 parts of potassium chloride by weight, spraying 10 parts of a polyglutamic acid solution, granulating at 45° C. for 5 hours, and drying at 80° C. for 1 hour to obtain a core material; dissolving 15 parts of polylactic acid in 40 parts of dichloromethane, adding 2 parts of nano-silicon dioxide and 1 part of magnesium stearate, and ultrasonically dispersing to obtain a coating liquid; preheating the core material to 40° C., spraying the film at 8 mL / min in a fluidized bed, with an atomization pressure of 0.15 MPa, and curing at 50° C. for 2 hours.

7. The method for preparing a sour orange seedling culture medium according to claim 1, wherein The preparation method of the composite bacterial agent includes: inoculating Bacillus subtilis CGMCC 1.1086 seed liquid into a culture medium, aerating at a ratio of 1:1.0 vvm, and fermenting at 250 rpm for 36 hours; mixing Bacillus subtilis fermentation liquid with Rhizophagus irregularis DAOM 197198 spore powder; adding skimmed milk powder, trehalose, and glycerol; spray drying; prefreezing to -40°C; and vacuum drying for 12 hours.

8. The method for preparing a sour orange seedling culture medium according to claim 7, wherein The seed liquid of Bacillus subtilis CGMCC 1.1086 was inoculated into a culture medium containing 20 g / L sucrose and 15 g / L soybean meal.

9. An application of the method for preparing a sour orange seedling culture medium according to any one of claims 1 to 8, characterized in that: Sow in a 32-hole tray, sow 3 orange seeds in each hole, and cover with 1 cm of soil.

10. The preparation method according to claim 9, characterized in that The day temperature was controlled at 25°C / night temperature at 18°C, the light intensity was 30,000 Lux, the humidity was 60%, and the gravimetric method was used to maintain the water holding capacity of the matrix at 70%.