Seedling raising substrate and process for preparing the same

Abstract

The present application relates to the technical field of seedling raising substrate, and particularly relates to a seedling raising substrate and a preparation process thereof.The seedling raising substrate comprises, from bottom to top, a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water retaining layer and a second fiber matrix layer.The thickness ratio of the vermiculite particle layer, the first fiber matrix layer, the temperature-sensitive water retaining layer and the second fiber matrix layer is 8-12:15-25:1-3:10-20.The vermiculite particle layer establishes a rapid water conducting channel, and the first fiber matrix layer, the temperature-sensitive water retaining layer and the second fiber matrix layer cooperate to realize slow release of nutrients and water, effectively maintain the pore aeration rate of the substrate, and the nutrient structure of the substrate is reasonable, facilitating plant absorption, providing sufficient nutrient elements for plant growth and meeting the needs of plant growth.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seedling raising substrate, and particularly relates to a seedling raising substrate and a preparation process thereof. BACKGROUND

[0002] In modern intensive seedling production, the seedling raising substrate is a physical support and nutrient supply carrier for root development, and its dynamic water and gas balance ability and nutrient release efficiency are key factors determining the health of seedlings.

[0003] Traditional seedling raising substrates mainly use peat, coconut husk, perlite and other materials, which have the advantage of high initial porosity (about 65-90%), but are prone to structure densification under continuous irrigation, resulting in decreased pore connectivity, increased bulk density and reduced effective porosity, and further causing root hypoxia and nutrient retention imbalance.

[0004] Under high-frequency irrigation conditions, the hydroxyl groups on the surface of organic fibers in peat substrates easily react with calcium and magnesium ions in irrigation water to form colloidal sediments that block pores. This densification process severely hinders oxygen diffusion, causing high carbon dioxide concentration around the roots, directly inhibiting the activity of cytochrome oxidase in the mitochondrial respiratory chain, leading to decreased root activity and greatly increased root tip browning rate of seedlings.

[0005] Conventional water-retaining materials, such as polyacrylamide (PAM), can absorb 300-500 times their own weight of water, but due to the lack of temperature response mechanism, water release often lags behind plant transpiration, causing severe fluctuations in rhizosphere environment, damaging root cell membrane stability, causing abnormal accumulation of osmotic regulation substances, and increasing seedling wilting rate.

[0006] Existing technologies mostly use mineral materials such as vermiculite and zeolite as slow-release carriers to improve water retention and air permeability. However, such structures are prone to interface water congestion when temperature and humidity change suddenly, making it difficult to achieve on-demand release of water and nutrients, severely restricting crop metabolic efficiency, and resulting in low seedling survival rate, which needs to be addressed. SUMMARY

[0007] The present application aims to solve the problems in the prior art and provides a seedling raising substrate and a preparation process thereof.

[0008] A seedling raising substrate, from bottom to top, comprises a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer. The thickness ratio of the vermiculite particle layer, the first fiber matrix layer, the temperature-sensitive water-retaining layer, and the second fiber matrix layer is 8-12:15-25:1-3:10-20.

[0009] Preferably, the porosity of the vermiculite particle layer is ≥85%.

[0010] Preferably, the raw material of the first and second fiber matrix layers are both porous fiber matrix; the raw material of the porous fiber matrix includes, by mass fraction, 15-25 parts of rice husk, 3-8 parts of corn straw, 20-40 parts of nano-silica dispersion liquid, and 0.05-0.1 parts of silane coupling agent KH-550.

[0011] Preferably, the porous fiber matrix is prepared by the following steps: mixing and crushing the rice husk and corn straw to a particle size of ≤1.5 mm, immersing in a citric acid solution, adjusting the pH to 4-5, ultrasonic treatment at 55-60℃ for 40-60 min, adding nano-silica dispersion liquid and silane coupling agent KH-550 and ultrasonic treatment for 10-30 min, centrifugal separation, water washing to neutral, and freeze-drying.

[0012] Preferably, the concentration of the citric acid solution is 0.5-1.0 mol / L.

[0013] Preferably, the ultrasonic treatment frequency after adjusting the pH to 4-5 is 35-40 kHz; and the ultrasonic treatment frequency after adding the nano-silica dispersion liquid and silane coupling agent KH-550 is 30-40 kHz.

[0014] Preferably, the raw material of the temperature-sensitive water-retaining layer is temperature-responsive gel particles; the raw material of the temperature-responsive gel particles includes, by mass fraction, 8-15 parts of humus soil, 2-6 parts of wheat bran, 80-150 parts of urea solution, 0.5-1.5 parts of sodium alginate, 3-5 parts of N-vinyl caprolactam, 0.1-0.3 parts of photoinitiator, and 1-2 parts of calcium chloride solution; wherein the concentration of the urea solution is 0.8-1.2 mol / L, and the concentration of the calcium chloride solution is 0.1-0.5 mol / L.

[0015] Preferably, the temperature-responsive gel particles are prepared by the following steps: adding the humus soil and wheat bran to the urea solution, stirring at 70-80℃ for 1-2 h, reducing to 40℃, and adding the N-vinyl caprolactam, sodium alginate, and photoinitiator under nitrogen protection, stirring uniformly, adding the calcium chloride solution dropwise, ultraviolet curing after the dropwise addition is complete, and drying.

[0016] Preferably, the ultraviolet curing time is 40-90 s, the ultraviolet light wavelength is 365 nm, and the ultraviolet light intensity is 70-90 mW / cm 2 .

[0017] The preparation process of the above-mentioned seedling substrate includes the following steps: sequentially laying the vermiculite particle layer, the first fiber matrix layer, the temperature-sensitive water-retaining layer, and the second fiber matrix layer from bottom to top, rolling 2 times, each time for 1-1.5 min, and the rolling pressure being 0.8-1.0 MPa; and then irradiation sterilization 2 times, with an interval of 24-36 h between the two irradiation sterilizations.

[0018] Preferably, the irradiation sterilization is carried out by using a 60Co source with a dose of 25-35 kGy. 60Co-gamma irradiation sterilization, each irradiation dose is 3-10 kGy.

[0019] Beneficial effects:

[0020] The vermiculite particle layer of the present application establishes a rapid water channel, and the middle passes through the first fiber matrix layer, the temperature-sensitive water retention layer and the second fiber matrix layer to cooperatively release nutrients and water, effectively maintaining the pore aeration rate of the substrate. Meanwhile, the nutrient structure of the substrate is reasonable, facilitating the absorption of plants and providing sufficient nutrient elements for the growth of plants, meeting the needs of plant growth. The germination rate can be as high as 91% or more when the seedling substrate of the present application is used for seedling culture. The rooting rate of cuttings can be as high as 92% or more when the seedling substrate of the present application is used for flower cutting, improving the survival rate of cuttings.

[0021] The present application adopts rice husk and corn straw, which are etched by citric acid and enhanced by nano-silicon dioxide, to form a porous fiber matrix in a three-dimensional network structure. The wet compressive strength of the fiber matrix is significantly enhanced compared with traditional coconut coir substrates. Meanwhile, the Si-O-C covalent bond is formed on the surface of the fiber, which significantly inhibits the swelling and deformation of the fiber. The fiber is compounded with temperature-responsive gel particles. After 100 dry-wet cycles, the pore collapse rate is less than 6%, and the stability of the seedling substrate is greatly enhanced. The physical properties of the seedling substrate obtained by the present application are stable. On the basis of ensuring the increase of porosity, the substrate collapse rate is low, which can provide a continuous and stable oxygen diffusion channel for the root system, avoiding the problem of increasing the incidence of root rot caused by densification of the structure.

[0022] The temperature-responsive gel particles used in the present application use poly-N-vinyl caprolactam (LCST=33℃) as the temperature-sensitive main body, and sodium alginate-Ca 2 + crosslinking network as the ion response unit. The phase transition temperature (32-35℃) matches the peak period of plant transpiration, and cooperates with the Ca 2 + response characteristics of sodium alginate, which can effectively release water quickly at high temperature, effectively ensuring the survival rate of seedling culture; when the environmental temperature rises to 32-35℃ (peak period of plant transpiration), the gel particles shrink and the water release rate increases, which is highly matched with the high water demand of seedlings. At the same time, the organic acid secreted by the root system can locally reduce the pH value, effectively trigger the de-crosslinking of the calcium alginate network, and realize the Ca 2 + controlled water gradient release.

[0023] The preparation process of the seedling substrate of the present application is simple, which reduces the production cost of the cultivation substrate and is suitable for large-scale popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The bulk density and collapse rate comparison chart of the seedling substrates obtained in Example 5 and Comparative Examples 1-2.

[0025] Figure 2The total porosity and saturated water content of the seedling substrate obtained in Example 5 and Comparative Examples 1-2 are compared.

[0026] Figure 3 The germination rate of seedlings of Paeonia suffruticosa grown using the seedling substrate obtained in Example 5 and Comparative Examples 1-2 is compared.

[0027] Figure 4 The survival rate and root length of cuttings of Impatiens walleriana grown using the seedling substrate obtained in Example 5 and Comparative Examples 1-2 are compared. DETAILED DESCRIPTION

[0028] The application is further described below in conjunction with specific examples.

[0029] The expanded vermiculite used below is purchased from a certain Bin Mine Product Trading Co., Ltd. in Lingshou County, and has a particle size of 3-6 mm. The nanosilica dispersion liquid is purchased from a certain Tai Metal Material Co., Ltd. in Qinghe County, and has a silica content of 25% and a particle size of 15±5 nm.

[0030] Example 1

[0031] A seedling substrate comprises, from bottom to top, a vermiculite particle layer with a thickness of 8 mm, a first fibrous matrix layer with a thickness of 15 mm, a temperature-sensitive water-retaining layer with a thickness of 1 mm, and a second fibrous matrix layer with a thickness of 10 mm. The vermiculite particle layer has a porosity of ≥85%.

[0032] The raw material of the first fibrous matrix layer and the second fibrous matrix layer is a porous fibrous matrix. The porous fibrous matrix is prepared by the following steps: 150 g of rice husk and 30 g of corn straw are mixed and crushed to a particle size of ≤1.5 mm, immersed in 600 g of a citric acid solution with a concentration of 0.5 mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is performed at 55°C for 40 min at an ultrasonic frequency of 35 kHz; 200 g of nanosilica dispersion liquid and 0.5 g of silane coupling agent KH-550 are added and ultrasonic treatment is performed for 10 min at an ultrasonic frequency of 30 kHz, followed by centrifugal separation, water washing until neutral, and freeze-drying until the water content is ≤5%.

[0033] The raw material of the temperature-sensitive water-retaining layer is temperature-responsive gel particles. The temperature-responsive gel particles are prepared by the following steps: 80 g of humus soil and 20 g of wheat bran are added to 800 g of a urea solution with a concentration of 0.8 mol / L, stirred at a temperature of 70°C for 1 h, reduced to 40°C, and then 30 g of N-vinyl caprolactam, 5 g of sodium alginate, and 1 g of a photoinitiator (Irgacure 2959) are added in sequence under nitrogen protection, stirred uniformly, 10 g of a calcium chloride solution with a concentration of 0.1 mol / L is added dropwise, and after the addition is completed, ultraviolet light with a wavelength of 365 nm is used for curing for 40 s at an ultraviolet light intensity of 70 mW / cm 2 , and dried at 50°C.

[0034] The preparation process of the seedling substrate comprises the following steps: sequentially laying, from bottom to top, a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer, and rolling twice, 1 min each time, at a rolling pressure of 0.8 MPa; then adopting 60 Co-γ ray irradiation sterilization twice, with an irradiation dose of 8 kGy each time, and an interval of 24 h between the two times of irradiation sterilization.

[0035] Example 2

[0036] A seedling substrate comprises, from bottom to top, a vermiculite particle layer with a thickness of 12 mm, a first fiber matrix layer with a thickness of 25 mm, a temperature-sensitive water-retaining layer with a thickness of 2 mm, and a second fiber matrix layer with a thickness of 20 mm. The vermiculite particle layer has a porosity of ≥ 85%.

[0037] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices, which are prepared by the following steps: mixing 250 g of rice husk and 80 g of corn straw to a particle size of ≤ 1.5 mm, immersing them in 1200 g of a citric acid solution with a concentration of 1.0 mol / L, adjusting the pH to 4-5, and ultrasonic treating at 60℃ for 60 min at an ultrasonic frequency of 40 kHz; adding 400 g of a nano-silicon dioxide dispersion and 1 g of a silane coupling agent KH-550, ultrasonic treating for 30 min at an ultrasonic frequency of 40 kHz, centrifugal separation, washing with water until neutral, and freeze-drying until the water content is ≤ 5%.

[0038] The raw material of the temperature-sensitive water-retaining layer is temperature-responsive gel particles, which are prepared by the following steps: adding 150 g of humus soil and 60 g of wheat bran to 1500 g of a urea solution with a concentration of 1.2 mol / L, stirring at a temperature of 80℃ for 2 h, reducing the temperature to 40℃, and sequentially adding 50 g of N-vinyl caprolactam, 15 g of sodium alginate, and 3 g of a photoinitiator (Irgacure 2959) under nitrogen protection, stirring uniformly, adding 20 g of a calcium chloride solution with a concentration of 0.5 mol / L dropwise, curing for 90 s under ultraviolet light with a wavelength of 365 nm after the dropwise addition is completed, and drying at 60℃. 2

[0039] The preparation process of the seedling substrate comprises the following steps: sequentially laying, from bottom to top, a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer, and rolling twice, 1.5 min each time, at a rolling pressure of 1.0 MPa; then adopting 60 Co-γ ray irradiation sterilization twice, with an irradiation dose of 10 kGy each time, and an interval of 36 h between the two times of irradiation sterilization.

[0040] Example 3

[0041] ​A seedling raising substrate comprises, from bottom to top, a vermiculite particle layer with a thickness of 9 mm, a first fiber matrix layer with a thickness of 22 mm, a temperature-sensitive water retaining layer with a thickness of 1.5 mm, and a second fiber matrix layer with a thickness of 18 mm.

[0042] The first fiber matrix layer and the second fiber matrix layer are both made of porous fiber matrix, which is prepared by the following steps: 180 g of rice husk and 60 g of corn straw are mixed and crushed to a particle size of less than or equal to 1.5 mm, then immersed in 800 g of a citric acid solution with a concentration of 0.8 mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is performed at 57°C for 55 min at an ultrasonic frequency of 36 kHz; 350 g of nano-silicon dioxide dispersion liquid and 0.6 g of silane coupling agent KH-550 are added and ultrasonic treatment is performed for 25 min at an ultrasonic frequency of 33 kHz, then centrifugal separation is performed, water washing is performed until neutral, and freeze-drying is performed until the water content is less than or equal to 5%.

[0043] The temperature-sensitive water retaining layer is made of temperature-responsive gel particles, which are prepared by the following steps: 140 g of humus soil and 30 g of wheat bran are added to 1300 g of a urea solution with a concentration of 0.9 mol / L, stirring is performed at a temperature of 77°C for 80 min, the temperature is then lowered to 40°C, 45 g of N-vinyl caprolactam, 8 g of sodium alginate, and 2.5 g of a photoinitiator (Irgacure 2959) are sequentially added under nitrogen protection, stirring is performed until uniform, 13 g of a calcium chloride solution with a concentration of 0.4 mol / L is added dropwise, after the dropwise addition is completed, ultraviolet light with a wavelength of 365 nm is used for curing for 50 s at an ultraviolet light intensity of 85 mW / cm 2 , and then dried at 52°C.

[0044] The preparation process of the seedling raising substrate comprises the following steps: vermiculite particle layer, first fiber matrix layer, temperature-sensitive water retaining layer, and second fiber matrix layer are sequentially laid from bottom to top, and roller pressing is performed twice, each time for 1.5 min, the roller pressing pressure is 0.85 MPa; then Co-γ ray irradiation sterilization is performed twice, each time with an irradiation dose of 9.5 kGy, and the interval between the two irradiation sterilizations is 26 h. 60 Co-γ ray irradiation sterilization is performed twice, each time with an irradiation dose of 9.5 kGy, and the interval between the two irradiation sterilizations is 26 h.

[0045] Example 4

[0046] A seedling raising substrate comprises, from bottom to top, a vermiculite particle layer with a thickness of 11 mm, a first fiber matrix layer with a thickness of 18 mm, a temperature-sensitive water retaining layer with a thickness of 3 mm, and a second fiber matrix layer with a thickness of 12 mm. The vermiculite particle layer has a porosity of greater than or equal to 85%.

[0047] The raw material of the first and second fiber matrix layers is a porous fiber matrix; the porous fiber matrix is prepared by the following steps: 220 g of rice husk and 40 g of corn straw are mixed and crushed to a particle size of ≤1.5 mm, then immersed in 1000 g of a citric acid solution with a concentration of 0.6 mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is performed at 59°C for 45 min at an ultrasonic frequency of 39 kHz; 250 g of a nano-silicon dioxide dispersion and 0.9 g of a silane coupling agent KH-550 are added and ultrasonic treatment is performed for 15 min at an ultrasonic frequency of 39 kHz, then centrifugal separation is performed, washed with water until neutral, and freeze-dried until the water content is ≤5%.

[0048] The raw material of the temperature-sensitive water-retention layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 100 g of humus soil and 50 g of wheat bran are added to 1000 g of a urea solution with a concentration of 1.1 mol / L, stirred at a temperature of 73°C for 100 min, then reduced to 40°C, and 35 g of N-vinyl caprolactam, 12 g of sodium alginate, and 1.5 g of a photoinitiator (Irgacure 2959) are sequentially added under nitrogen protection, stirred uniformly, 17 g of a calcium chloride solution with a concentration of 0.2 mol / L is added dropwise, after the dropwise addition is completed, ultraviolet light with a wavelength of 365 nm is used for curing for 80 s at an ultraviolet light intensity of 75 mW / cm 2 , and dried at 58°C.

[0049] The preparation process of the seedling substrate includes the following steps: the vermiculite particle layer, the first fiber matrix layer, the temperature-sensitive water-retention layer, and the second fiber matrix layer are sequentially laid from bottom to top, and rolled twice, each time for 1 min, at a rolling pressure of 0.95 MPa; then 60 Co-γ-ray irradiation sterilization is performed twice, each time at a dose of 8.5 kGy, and the interval between the two irradiation sterilizations is 34 h.

[0050] Example 5

[0051] A seedling substrate includes, from bottom to top: a vermiculite particle layer with a thickness of 10 mm, a first fiber matrix layer with a thickness of 20 mm, a temperature-sensitive water-retention layer with a thickness of 2 mm, and a second fiber matrix layer with a thickness of 15 mm. The vermiculite particle layer has a porosity of ≥85%.

[0052] The raw material of the first and second fiber matrix layers is a porous fiber matrix; the porous fiber matrix is prepared by the following steps: 200g of rice husk and 50g of corn straw are mixed and crushed to a particle size of ≤1.5mm, immersed in 900g of a citric acid solution with a concentration of 0.7mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is performed at 58℃ for 50min at an ultrasonic frequency of 38kHz; 300g of a nano-silicon dioxide dispersion and 0.8g of a silane coupling agent KH-550 are added and ultrasonic treatment is performed for 20min at an ultrasonic frequency of 36kHz, centrifugal separation is performed, water washing is performed until neutral, and freeze-drying is performed until the water content is ≤5%.

[0053] The raw material of the temperature-sensitive water-retention layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 120g of humus soil and 40g of wheat bran are added to 1200g of a urea solution with a concentration of 1.0mol / L, stirring is performed at a temperature of 75℃ for 90min, the temperature is lowered to 40℃, 40g of N-vinyl caprolactam, 10g of sodium alginate, and 2g of a photoinitiator (Irgacure 2959) are sequentially added under nitrogen protection, stirring is performed until uniform, 15g of a calcium chloride solution with a concentration of 0.3mol / L is added dropwise, after the dropwise addition is complete, ultraviolet light curing is performed for 65s using ultraviolet light with a wavelength of 365nm and an ultraviolet light intensity of 80mW / cm 2 , drying is performed at a temperature of 55℃, and post-processing is performed.

[0054] During the post-processing, the product is soaked in 10 times the amount of deionized water, stirring is performed at a temperature of 40℃ for 20min at a stirring speed of 25r / min, the process is repeated 4 times with deionized water being replaced each time, low-speed centrifugal separation is performed, and drying is performed at a temperature of 55℃ until the weight is constant.

[0055] The preparation process of the seedling substrate includes the following steps: the vermiculite particle layer, the first fiber matrix layer, the temperature-sensitive water-retention layer, and the second fiber matrix layer are sequentially laid from bottom to top, and rolling is performed 2 times, each time for 1min, and the rolling pressure is 0.9MPa; then 60 Co-γ ray irradiation sterilization is performed 2 times, each time with a radiation dose of 3.5kGy, and the interval between the 2 times of irradiation sterilization is 30h.

[0056] Comparative Example 1

[0057] A seedling substrate includes, from bottom to top: a vermiculite particle layer with a thickness of 10mm, a first fiber matrix layer with a thickness of 20mm, a temperature-sensitive water-retention layer with a thickness of 2mm, and a second fiber matrix layer with a thickness of 15mm. The vermiculite particle layer has a porosity of ≥85%.

[0058] The raw material of the first and second fibrous matrix layers is a porous fibrous matrix; the porous fibrous matrix is prepared by the following steps: 200 g of rice husk and 50 g of corn straw are mixed and crushed to a particle size of ≤1.5 mm, immersed in a 900 g citric acid solution with a concentration of 0.7 mol / L, the pH is adjusted to 4-5, ultrasonic treatment is performed at 58℃ for 50 min, the ultrasonic frequency is 38 kHz, centrifugal separation is performed, washed with water until neutral, and freeze-dried until the water content is ≤5%.

[0059] The raw material of the temperature-sensitive water-retaining layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 120 g of humus soil and 40 g of wheat bran are added to 1200 g of a urea solution with a concentration of 1.0 mol / L, stirred at a temperature of 75℃ for 90 min, reduced to 40℃, and then 40 g of N-vinyl caprolactam, 10 g of sodium alginate, and 2 g of a photoinitiator (Irgacure 2959) are added under nitrogen protection and stirred uniformly, 15 g of a calcium chloride solution with a concentration of 0.3 mol / L is added dropwise, after the dropwise addition is completed, ultraviolet light with a wavelength of 365 nm is used for curing for 65 s, the ultraviolet light intensity is 80 mW / cm 2 , dried at 55℃, and post-processed.

[0060] During the post-processing, the product is soaked in 10 times the amount of deionized water, stirred at a temperature of 40℃ for 20 min at a stirring speed of 25 r / min, repeated 4 times with deionized water replaced each time, low-speed centrifugation, and dried at a temperature of 55℃ to a constant weight.

[0061] The preparation process of the above-mentioned seedling substrate includes the following steps: the vermiculite particle layer, the first fibrous matrix layer, the temperature-sensitive water-retaining layer, and the second fibrous matrix layer are sequentially laid from bottom to top, and rolled 2 times, each time for 1 min, with a rolling pressure of 0.9 MPa; then 60 Co-γ ray irradiation sterilization 2 times, each irradiation dose is 3.5 kGy, and the interval between the two irradiation sterilizations is 30 h.

[0062] Comparative Example 2

[0063] A seedling substrate, from bottom to top, includes: a vermiculite particle layer with a thickness of 10 mm, a first fibrous matrix layer with a thickness of 20 mm, a water-retaining layer with a thickness of 2 mm, and a second fibrous matrix layer with a thickness of 15 mm. Among them, the porosity of the vermiculite particle layer is ≥85%.

[0064] The raw material of the first and second fibrous matrix layers is a porous fibrous matrix; the porous fibrous matrix is prepared by the following steps: 200 g of rice husk and 50 g of corn straw are mixed and crushed to a particle size of ≤1.5 mm, immersed in 900 g of a citric acid solution with a concentration of 0.7 mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is performed at 58℃ for 50 min at an ultrasonic frequency of 38 kHz; 300 g of a nano-silicon dioxide dispersion and 0.8 g of a silane coupling agent KH-550 are added and ultrasonic treatment is performed for 20 min at an ultrasonic frequency of 36 kHz, centrifugal separation is performed, water washing is performed until neutral, and freeze-drying is performed until the water content is ≤5%.

[0065] The raw material of the water-retaining layer is a gel particle; the gel particle is prepared by the following steps: 120 g of humus soil and 40 g of wheat bran are added to 1200 g of a urea solution with a concentration of 1.0 mol / L, stirring is performed at a temperature of 75℃ for 90 min, the temperature is lowered to 40℃, 10 g of sodium alginate is added under nitrogen protection and stirring is performed until uniform, 15 g of a calcium chloride solution with a concentration of 0.3 mol / L is added dropwise, drying is performed at 55℃ after the dropwise addition is completed, and post-processing is performed.

[0066] During the post-processing, the product is soaked in 10 times the system deionized water, stirring is performed at a temperature of 40℃ for 20 min at a stirring speed of 25 r / min, the process is repeated 4 times with deionized water being replaced each time, low-speed centrifugal separation is performed, and drying is performed at a temperature of 55℃ until the constant weight.

[0067] The preparation process of the above-mentioned seedling raising substrate includes the following steps: the vermiculite particle layer, the first fibrous matrix layer, the temperature-sensitive water-retaining layer, and the second fibrous matrix layer are sequentially laid from bottom to top, and rolling is performed 2 times, each time for 1 min, and the rolling pressure is 0.9 MPa; then the 60 Co-γ ray irradiation sterilization is performed 2 times, each time with an irradiation dose of 3.5 kGy, and the interval between the 2 times of irradiation sterilization is 30 h.

[0068] The physical properties of the seedling raising substrates obtained in Example 5 and Comparative Examples 1-2 are detected. As shown in Figure 1 and Figure 2 The bulk density and the collapse rate of the seedling raising substrate obtained in Example 5 are the smallest, and the total porosity and the saturated water content are the largest, which are superior to those of Comparative Examples 1-2 (P<0.05).

[0069] A substrate seedling raising test is performed in a seedling planting base in Hebei, and the seedlings of Clausiusia are taken as the experimental objects, and the seedlings are raised by using the seedling raising substrates obtained in Example 5 and Comparative Examples 1-2. Each group has 3 repetitions, and each repetition has 24 plants. A large diurnal temperature difference is set (the highest temperature in the day is 36℃, and the lowest temperature at night is 20℃), and the air humidity is 95%. The germination rate is investigated 40 d after sowing.

[0070] As shown in Figure 3As shown, the germination rate of seedlings raised using the seedling substrate obtained in Example 5 was the highest, which was better than that of Comparative Examples 1-2 (P<0.05).

[0071] A cutting propagation experiment was conducted at a seedling planting base in Hebei Province, using New Guinea impatiens as the experimental subject. Three replicates were established for the seedling substrates obtained in Example 5 and Comparative Examples 1-2, with 15 cuttings per replicate (cuttings taken from young buds in the leaf axils of the mother plant). Full-light mist propagation technology was used, with an air humidity of 80-90% and a large diurnal temperature range (daytime high 36℃, nighttime low 20℃); the plant spacing was 5-6 cm, and the row spacing was 7-8 cm; foliar fertilizer was sprayed once during the experiment, and watering was uniform. After two weeks, the survival rate and root length of each group were recorded.

[0072] like Figure 4 As shown, the cuttings were propagated using the seedling substrate obtained in Example 5, and the survival rate and root length were the highest, which were superior to those of Comparative Examples 1-2 (P<0.05).

[0073] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A nursery substrate, characterized in that, From bottom to top comprises: A vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retention layer, and a second fiber matrix layer; the thickness ratio of the vermiculite particle layer, the first fiber matrix layer, the temperature-sensitive water-retention layer, and the second fiber matrix layer is 8-12:15-25:1-3:10-20; The raw material of the first fiber matrix layer and the second fiber matrix layer is a porous fiber matrix; the raw material of the porous fiber matrix comprises, by mass fraction: 15-25 parts of rice husk, 3-8 parts of corn straw, 20-40 parts of a nano-silicon dioxide dispersion, and 0.05-0.1 parts of silane coupling agent KH-550; The raw material of the temperature-sensitive water-retention layer is a temperature-responsive gel particle; the raw material of the temperature-responsive gel particle comprises, by mass fraction: 8-15 parts of humus soil, 2-6 parts of wheat bran, 80-150 parts of a urea solution, 0.5-1.5 parts of sodium alginate, 3-5 parts of N-vinyl caprolactam, 0.1-0.3 parts of a photoinitiator, and 1-2 parts of a calcium chloride solution; the concentration of the urea solution is 0.8-1.2 mol / L, and the concentration of the calcium chloride solution is 0.1-0.5 mol / L; The temperature-responsive gel particle is prepared by the following steps: adding the humus soil and the wheat bran to the urea solution, stirring at 70-80℃ for 1-2 hours, reducing to 40℃, and then adding the N-vinyl caprolactam, the sodium alginate, and the photoinitiator under nitrogen protection, stirring uniformly, adding the calcium chloride solution dropwise, ultraviolet curing after the dropwise addition is completed, and drying.

2. The nursery substrate according to claim 1, characterized in that, The porosity of the vermiculite particle layer is ≥85%.

3. The growing medium according to claim 1, wherein, The porous fiber matrix is prepared by the following steps: mixing and crushing the rice husk and the corn straw to a particle size of ≤1.5 mm, immersing them in a citric acid solution, adjusting the pH to 4-5, ultrasonic treatment at 55-60℃ for 40-60 minutes, adding the nano-silicon dioxide dispersion and the silane coupling agent KH-550, ultrasonic treatment for 10-30 minutes, centrifugal separation, water washing until neutral, and freeze-drying.

4. The growing medium of claim 1, wherein, The concentration of the citric acid solution is 0.5-1.0 mol / L.

5. The nursery substrate of claim 1, wherein The ultrasonic treatment frequency after adjusting the pH to 4-5 is 35-40 kHz; the ultrasonic treatment frequency after adding the nano-silicon dioxide dispersion and the silane coupling agent KH-550 is 30-40 kHz.

6. The nursery substrate of claim 1, wherein The ultraviolet curing time is 40-90 seconds, the ultraviolet light wavelength is 365 nm, and the ultraviolet light intensity is 70-90 mW / cm2.

7. A process for the preparation of a growing substrate as claimed in any one of claims 1 to 6, characterised in that, The method comprises the following steps: sequentially laying the vermiculite particle layer, the first fiber matrix layer, the temperature-sensitive water-retention layer, and the second fiber matrix layer from bottom to top, rolling 2 times, each time for 1-1.5 minutes, and the rolling pressure is 0.8-1.0 MPa; and then performing irradiation sterilization 2 times, with an interval of 24-36 hours between the two irradiation sterilizations.

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