Seedling raising substrate and preparation process thereof

Abstract

The invention relates to the technical field of seedling substrates, in particular to a seedling substrate and a preparation process thereof. The seedling raising substrate comprises a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water retention layer and a second fiber matrix layer from bottom to top, the thickness ratio of the vermiculite particle layer to the first fiber matrix layer to the temperature-sensitive water retention layer to the second fiber matrix layer is (8-12): (15-25): (1-3): (10-20). The vermiculite particle layer builds a rapid water guide channel, the first fiber matrix layer, the temperature-sensitive water retention layer and the second fiber matrix layer in the middle synergistically achieve slow release of nutrients and water, the pore ventilation rate of the matrix is effectively maintained, meanwhile, the matrix is reasonable in nutrition structure and convenient to absorb by plants, sufficient nutrient elements are provided for growth of the plants, and the survival rate of the plants is increased. The plant growth requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of seedling cultivation substrates, and in particular to a seedling cultivation substrate and a preparation process thereof. Background Art

[0002] In modern intensive seedling production, the seedling medium serves as the physical support for root development and a carrier for nutrient supply. Its dynamic water-gas balance capacity and nutrient slow-release efficiency are key factors in determining the robustness of the seedlings.

[0003] Traditional seedling substrates are mainly composed of peat, coconut bran, perlite and other materials. Although they have the advantage of high initial porosity (about 65-90%), they are prone to structural densification under continuous irrigation, resulting in a decrease in pore connectivity, which is manifested as an increase in bulk density and a decrease in effective porosity, which in turn causes root hypoxia and nutrient retention imbalance.

[0004] Under high-frequency irrigation conditions, the hydroxyl groups on the surface of organic fibers in peat-based matrices easily react with calcium and magnesium ions in the irrigation water to form colloidal sediments that block the pores. This densification process seriously hinders oxygen diffusion, causing the carbon dioxide concentration around the roots to be too high, directly inhibiting the activity of cytochrome oxidase in the mitochondrial respiratory chain, resulting in a decrease in the vitality of the seedling roots and a greatly increased browning rate of the root tips.

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

[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 interfacial water congestion when temperature and humidity change suddenly, making it difficult to release water and nutrients on demand, which seriously restricts crop metabolic efficiency and low seedling survival rate, and needs to be solved urgently. Summary of the invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a seedling culture medium and a preparation process thereof.

[0008] A seedling culture matrix 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.

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

[0010] Preferably, the raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the raw materials of the porous fiber matrix include, by mass: 15-25 parts of rice husk, 3-8 parts of corn stalks, 20-40 parts of nano-silicon dioxide dispersion, 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 rice husks and corn stalks and crushing them to a particle size of ≤1.5 mm, immersing them in a citric acid solution, adjusting the pH to 4-5, ultrasonically treating them at 55-60°C for 40-60 minutes, adding a nano-silicon dioxide dispersion and a silane coupling agent KH-550, ultrasonically treating them for 10-30 minutes, centrifuging, washing with water until neutral, and freeze-drying.

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

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

[0014] Preferably, the raw material of the temperature-sensitive water-retaining layer is temperature-responsive gel particles; the raw materials of the temperature-responsive gel particles include, by mass: 8-15 parts of humus, 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 humus and wheat bran to a urea solution, stirring at 70-80°C for 1-2h, reducing the temperature to 40°C, adding N-vinyl caprolactam, sodium alginate, and a photoinitiator in sequence under nitrogen protection, stirring evenly, adding a calcium chloride solution dropwise, curing with ultraviolet light after the addition is complete, and drying.

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

[0017] The preparation process of the above-mentioned seedling substrate includes the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1-1.5 minutes, and a rolling pressure of 0.8-1.0MPa; then irradiating and sterilizing twice, with an interval of 24-36 hours between the two irradiation sterilizations.

[0018] Preferably, using 60Co-γ ray irradiation sterilization, each irradiation dose is 3-10kGy.

[0019] Beneficial effects:

[0020] The vermiculite particle layer of the present invention establishes a rapid water-conducting channel, and the first fiber matrix layer, the temperature-sensitive water-retaining layer, and the second fiber matrix layer in the middle cooperate to achieve the slow release of nutrients and water, effectively maintaining the porosity of the matrix. At the same time, the nutritional structure of the matrix of the present invention is reasonable, which is convenient for plant absorption, provides sufficient nutrients for the growth of plants, and meets the needs of plant growth. The germination rate can be as high as 91% or more when the seedling raising matrix of the present invention is used for seedling raising. The rooting rate of cuttings can be as high as 92% or more when the seedling raising matrix of the present invention is used for flower cuttings, thereby improving the survival rate of cuttings.

[0021] The present invention uses rice husks and corn stalks etched with citric acid and reinforced with nano-silicon dioxide to form a porous fiber matrix with a three-dimensional network structure. The wet compressive strength is significantly enhanced compared with the traditional coconut bran matrix. At the same time, Si-OC covalent bonds are formed on the fiber surface, which significantly inhibits the fiber swelling and deformation. 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 matrix is ​​greatly enhanced. The physical properties of the seedling matrix obtained by the present invention are stable, and on the basis of ensuring the increase of porosity, the matrix collapse rate is low, which can provide a continuous and stable oxygen diffusion channel for the root system, avoiding the problem of increased incidence of root rot caused by structural densification.

[0022] The temperature-responsive gel particles used in the present invention are based on poly N-vinyl caprolactam (LCST = 33°C) as the temperature-sensitive main body, sodium alginate-Ca 2 + The cross-linked network is an ion-responsive unit, and its phase transition temperature (32-35°C) matches the peak period of plant transpiration, and the Ca 2 + responsive characteristics, which can effectively achieve rapid water release at high temperatures and effectively ensure the survival rate of seedlings; when the ambient temperature rises to 32-35℃ (peak period of plant transpiration), the gel particles undergo phase change and shrinkage, and the water release rate increases, which is highly matched with the transpiration water demand of the seedlings. At the same time, the organic acids secreted by the roots can locally reduce the pH value, effectively triggering the de-crosslinking of the calcium alginate network, and achieving Ca 2 +Controlled moisture gradient release.

[0023] The preparation process of the seedling culture matrix of the present invention is simple, the production cost of the culture matrix is ​​reduced, and the invention is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a comparison chart of the bulk density and collapse rate of the seedling culture medium obtained in Example 5 and Comparative Examples 1-2.

[0025] Figure 2It is a comparison chart of the total porosity and saturated water content of the seedling culture matrix obtained in Example 5 and Comparative Examples 1-2.

[0026] Figure 3 The figure is a comparison chart of the germination rates of cyclamen seeds grown using the seedling growing media obtained in Example 5 and Comparative Examples 1-2.

[0027] Figure 4 The following is a comparison chart of the survival rate and root length of Impatiens New Guinea cuttings grown using the seedling culture media obtained in Example 5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0028] The present invention will be further explained below in conjunction with specific embodiments.

[0029] The expanded vermiculite used below was purchased from Lingshou County Moubin Mineral Products Trading Co., Ltd., with a particle size of 3-6 mm. The nano-silicon dioxide dispersion was purchased from Qinghe County Moutai Metal Materials Co., Ltd., with a silicon dioxide content of 25% and a particle size of 15±5 nm.

[0030] Example 1

[0031] A seedling culture matrix comprises, from bottom to top: a vermiculite particle layer with a thickness of 8 mm, a first fiber matrix layer with a thickness of 15 mm, a temperature-sensitive water-retaining layer with a thickness of 1 mm, and a second fiber matrix layer with a thickness of 10 mm, wherein the porosity of the vermiculite particle layer is ≥85%.

[0032] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the porous fiber matrix is ​​prepared by the following steps: 150g of rice husks and 30g of corn stalks are mixed and crushed to a particle size of ≤1.5mm, immersed in 600g of 0.5mol / L citric acid solution, the pH value is adjusted to 4-5, and ultrasonic treatment is performed at 55°C for 40min, and the ultrasonic frequency is 35kHz; 200g of nano-silicon dioxide dispersion and 0.5g of silane coupling agent KH-550 are added, ultrasonic treatment is performed for 10min, and the ultrasonic frequency is 30kHz, centrifugal separation, water washing to neutrality, and freeze drying to a moisture content of ≤5%.

[0033] The raw material of the thermosensitive water-retaining layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 80 g of humus and 20 g of wheat bran are added to 800 g of 0.8 mol / L urea solution, stirred at 70 ° C for 1 hour, cooled to 40 ° C, and 30 g of N-vinyl caprolactam, 5 g of sodium alginate, and 1 g of photoinitiator (Irgacure2959) are added in sequence under nitrogen protection and stirred evenly, and 10 g of 0.1 mol / L calcium chloride solution is added dropwise, and after the addition is complete, ultraviolet light with a wavelength of 365 nm is used for curing for 40 seconds, and the ultraviolet light intensity is 70 mW / cm 2 , dried at 50℃.

[0034] The preparation process of the above-mentioned seedling substrate comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1 minute, and the rolling pressure is 0.8 MPa; and then using 60 Co-γ ray irradiation sterilization is performed twice, each irradiation dose is 8kGy, and the interval between the two irradiation sterilizations is 24h.

[0035] Example 2

[0036] A seedling culture matrix 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, wherein the porosity of the vermiculite particle layer is ≥85%.

[0037] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the porous fiber matrix is ​​prepared by the following steps: 250g of rice husks and 80g of corn stalks are mixed and crushed to a particle size of ≤1.5mm, immersed in 1200g of citric acid solution with a concentration of 1.0mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is carried out at 60°C for 60min, and the ultrasonic frequency is 40kHz; 400g of nano-silicon dioxide dispersion and 1g of silane coupling agent KH-550 are added, ultrasonic treatment is carried out for 30min, and the ultrasonic frequency is 40kHz, centrifugal separation, water washing to neutrality, and freeze drying to a moisture content of ≤5%.

[0038] The raw material of the thermosensitive water-retaining layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 150 g of humus and 60 g of wheat bran are added to 1500 g of urea solution with a concentration of 1.2 mol / L, stirred at 80 ° C for 2 h, cooled to 40 ° C, 50 g of N-vinyl caprolactam, 15 g of sodium alginate, and 3 g of photoinitiator (Irgacure2959) are added in sequence under nitrogen protection and stirred evenly, 20 g of calcium chloride solution with a concentration of 0.5 mol / L is added dropwise, and after the addition is complete, ultraviolet light with a wavelength of 365 nm is used for curing for 90 s, and the ultraviolet light intensity is 90 mW / cm 2 , dried at 60℃.

[0039] The preparation process of the above-mentioned seedling substrate comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1.5 minutes, and the rolling pressure is 1.0 MPa; and then using 60 Co-γ ray irradiation sterilization is performed twice, each irradiation dose is 10kGy, and the interval between the two irradiation sterilizations is 36h.

[0040] Example 3

[0041] A seedling culture matrix 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, wherein the porosity of the vermiculite particle layer is ≥85%.

[0042] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the porous fiber matrix is ​​prepared by the following steps: 180g of rice husks and 60g of corn stalks are mixed and crushed to a particle size of ≤1.5mm, immersed in 800g of 0.8mol / L citric acid solution, the pH is adjusted to 4-5, and ultrasonically treated at 57°C for 55min with an ultrasonic frequency of 36kHz; 350g of nano-silicon dioxide dispersion and 0.6g of silane coupling agent KH-550 are added, ultrasonically treated for 25min with an ultrasonic frequency of 33kHz, centrifuged, washed with water to neutrality, and freeze-dried to a moisture content of ≤5%.

[0043] The raw material of the thermosensitive water-retaining layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 140 g of humus and 30 g of wheat bran are added to 1300 g of 0.9 mol / L urea solution, stirred at 77 ° C for 80 min, cooled to 40 ° C, 45 g of N-vinyl caprolactam, 8 g of sodium alginate, and 2.5 g of photoinitiator (Irgacure2959) are added in sequence under nitrogen protection and stirred evenly, 13 g of 0.4 mol / L calcium chloride solution is added dropwise, and after the addition is complete, ultraviolet light with a wavelength of 365 nm is used for curing for 50 s, and the ultraviolet light intensity is 85 mW / cm 2 , dried at 52℃.

[0044] The preparation process of the above-mentioned seedling substrate comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1.5 minutes, and the rolling pressure is 0.85 MPa; and then using 60 Co-γ ray irradiation sterilization is performed twice, each irradiation dose is 9.5kGy, and the interval between the two irradiation sterilizations is 26h.

[0045] Example 4

[0046] A seedling culture matrix 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, wherein the porosity of the vermiculite particle layer is ≥85%.

[0047] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the porous fiber matrix is ​​prepared by the following steps: 220g of rice husks and 40g of corn stalks are mixed and crushed to a particle size of ≤1.5mm, immersed in 1000g of 0.6mol / L citric acid solution, the pH is adjusted to 4-5, and ultrasonically treated at 59°C for 45min with an ultrasonic frequency of 39kHz; 250g of nano-silicon dioxide dispersion and 0.9g of silane coupling agent KH-550 are added, ultrasonically treated for 15min with an ultrasonic frequency of 39kHz, centrifuged, washed with water to neutrality, and freeze-dried to a moisture content of ≤5%.

[0048] The raw material of the thermosensitive water-retaining 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 urea solution with a concentration of 1.1 mol / L, stirred at 73 ° C for 100 min, cooled to 40 ° C, 35 g of N-vinyl caprolactam, 12 g of sodium alginate, and 1.5 g of photoinitiator (Irgacure2959) are added in sequence under nitrogen protection and stirred evenly, 17 g of calcium chloride solution with a concentration of 0.2 mol / L is added dropwise, and after the addition is complete, ultraviolet light with a wavelength of 365 nm is used for curing for 80 s, and the ultraviolet light intensity is 75 mW / cm 2 , dried at 58°C.

[0049] The preparation process of the above-mentioned seedling substrate comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1 minute, and the rolling pressure is 0.95 MPa; and then using 60 Co-γ ray irradiation sterilization is performed twice, each irradiation dose is 8.5kGy, and the interval between the two irradiation sterilizations is 34h.

[0050] Example 5

[0051] A seedling culture matrix comprises, 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-retaining layer with a thickness of 2 mm, and a second fiber matrix layer with a thickness of 15 mm, wherein the porosity of the vermiculite particle layer is ≥85%.

[0052] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the porous fiber matrix is ​​prepared by the following steps: 200g of rice husks and 50g of corn stalks are mixed and crushed to a particle size of ≤1.5mm, immersed in 900g of citric acid solution with a concentration of 0.7mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is carried out at 58°C for 50min, and the ultrasonic frequency is 38kHz; 300g of nano-silicon dioxide dispersion and 0.8g of silane coupling agent KH-550 are added, ultrasonic treatment is carried out for 20min, and the ultrasonic frequency is 36kHz, centrifugal separation, washing with water to neutrality, and freeze-drying to a moisture content of ≤5%.

[0053] The raw material of the thermosensitive water-retaining layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 120 g of humus and 40 g of wheat bran are added to 1200 g of 1.0 mol / L urea solution, stirred at 75 ° C for 90 min, cooled to 40 ° C, 40 g of N-vinyl caprolactam, 10 g of sodium alginate, and 2 g of photoinitiator (Irgacure2959) are added in sequence under nitrogen protection and stirred evenly, 15 g of 0.3 mol / L calcium chloride solution is added dropwise, and after the addition is complete, ultraviolet light with a wavelength of 365 nm is used for curing for 65 s, and the ultraviolet light intensity is 80 mW / cm 2 , dried at 55℃ and post-processed.

[0054] During the post-treatment process, the product was immersed in 10 times the system deionized water, stirred at 40°C for 20 min, with a stirring speed of 25 r / min, repeated 4 times with the deionized water replaced each time, centrifuged at low speed, and dried at 55°C to constant weight.

[0055] The preparation process of the above-mentioned seedling substrate comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1 minute, and the rolling pressure is 0.9 MPa; and then using 60 Co-γ ray irradiation sterilization is performed twice, each irradiation dose is 3.5kGy, and the interval between the two irradiation sterilizations is 30h.

[0056] Comparative Example 1

[0057] A seedling culture matrix comprises, 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-retaining layer with a thickness of 2 mm, and a second fiber matrix layer with a thickness of 15 mm, wherein the porosity of the vermiculite particle layer is ≥85%.

[0058] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the porous fiber matrix is ​​prepared by the following steps: 200g rice husks and 50g corn stalks are mixed and crushed to a particle size of ≤1.5mm, immersed in 900g 0.7mol / L citric acid solution, the pH is adjusted to 4-5, ultrasonically treated at 58°C for 50min, the ultrasonic frequency is 38kHz, centrifuged, washed with water to neutrality, and freeze-dried to a moisture content of ≤5%.

[0059] The raw material of the thermosensitive water-retaining layer is temperature-responsive gel particles; the temperature-responsive gel particles are prepared by the following steps: 120 g of humus and 40 g of wheat bran are added to 1200 g of 1.0 mol / L urea solution, stirred at 75 ° C for 90 min, cooled to 40 ° C, 40 g of N-vinyl caprolactam, 10 g of sodium alginate, and 2 g of photoinitiator (Irgacure2959) are added in sequence under nitrogen protection and stirred evenly, 15 g of 0.3 mol / L calcium chloride solution is added dropwise, and after the addition is complete, ultraviolet light with a wavelength of 365 nm is used for curing for 65 s, and the ultraviolet light intensity is 80 mW / cm 2 , dried at 55℃ and post-processed.

[0060] During the post-treatment process, the product was immersed in 10 times the system deionized water, stirred at 40°C for 20 min, with a stirring speed of 25 r / min, repeated 4 times with the deionized water replaced each time, centrifuged at low speed, and dried at 55°C to constant weight.

[0061] The preparation process of the above-mentioned seedling substrate comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1 minute, and the rolling pressure is 0.9 MPa; and then using 60 Co-γ ray irradiation sterilization is performed twice, each irradiation dose is 3.5kGy, and the interval between the two irradiation sterilizations is 30h.

[0062] Comparative Example 2

[0063] A seedling culture matrix comprises, 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 water-retaining layer with a thickness of 2 mm, and a second fiber matrix layer with a thickness of 15 mm, wherein the porosity of the vermiculite particle layer is ≥85%.

[0064] The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrices; the porous fiber matrix is ​​prepared by the following steps: 200g of rice husks and 50g of corn stalks are mixed and crushed to a particle size of ≤1.5mm, immersed in 900g of citric acid solution with a concentration of 0.7mol / L, the pH is adjusted to 4-5, and ultrasonic treatment is carried out at 58°C for 50min, and the ultrasonic frequency is 38kHz; 300g of nano-silicon dioxide dispersion and 0.8g of silane coupling agent KH-550 are added, ultrasonic treatment is carried out for 20min, and the ultrasonic frequency is 36kHz, centrifugal separation, washing with water to neutrality, and freeze-drying to a moisture content of ≤5%.

[0065] The raw material of the water-retaining layer is gel particles; the gel particles are prepared by the following steps: 120g of humus and 40g of wheat bran are added to 1200g of 1.0mol / L urea solution, stirred at 75°C for 90min, cooled to 40°C, 10g of sodium alginate is added under nitrogen protection and stirred evenly, 15g of 0.3mol / L calcium chloride solution is added dropwise, dried at 55°C after the addition is complete, and post-processed.

[0066] During the post-treatment process, the product was immersed in 10 times the system deionized water, stirred at 40°C for 20 min, with a stirring speed of 25 r / min, repeated 4 times with the deionized water replaced each time, centrifuged at low speed, and dried at 55°C to constant weight.

[0067] The preparation process of the above-mentioned seedling substrate comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer, and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1 minute, and the rolling pressure is 0.9 MPa; and then using 60 Co-γ ray irradiation sterilization is performed twice, each irradiation dose is 3.5kGy, and the interval between the two irradiation sterilizations is 30h.

[0068] The physical properties of the seedling substrates obtained in Example 5 and Comparative Examples 1-2 were tested. Figure 1 and Figure 2 As shown, the bulk density and collapse rate of the seedling culture medium obtained in Example 5 are the smallest, while the total porosity and saturated water content are the largest, which is better than that of Comparative Examples 1-2 (P < 0.05).

[0069] A matrix seedling test was conducted at a seedling planting base in Hebei Province. Cyclamen seeds were used as experimental objects, and the seedlings were grown using the seedling medium obtained in Example 5 and Comparative Examples 1-2. Three replicates were set up in each group, with 24 plants in each replicate. A large temperature difference between day and night was set (maximum 36°C during the day and minimum 20°C at night), and the air humidity was 95%. The germination rate was investigated 40 days after sowing.

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

[0071] A cutting test was conducted at a nursery planting base in Hebei Province, with Impatiens balsamina as the experimental object. The seedling culture media obtained in Example 5 and Comparative Examples 1-2 were set up with 3 replicates each, with 15 cuttings in each replicate (cuttings were collected from young shoots between the leaf axils of the mother plant). Full light spray cutting technology was adopted, the air humidity was 80-90%, and a large temperature difference between day and night was set (maximum 36°C during the day, minimum 20°C at night); the cutting spacing was 5-6cm, and the row spacing was 7-8cm; during the test period, foliar fertilizer was sprayed once and watered uniformly. After 2 weeks, the survival rate and root length of each group were counted.

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

[0073] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A seedling culture medium, characterized in that: From bottom to top, this includes: Vermiculite particle layer, first fiber matrix layer, temperature-sensitive water-retaining layer, 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.

2. The seedling culture medium according to claim 1, characterized in that: The porosity of the vermiculite particle layer is ≥85%.

3. The seedling culture medium according to claim 1, characterized in that: The raw materials of the first fiber matrix layer and the second fiber matrix layer are both porous fiber matrixes; the raw materials of the porous fiber matrix include: 15-25 parts of rice husk, 3-8 parts of corn stalks, 20-40 parts of nano silicon dioxide dispersion, and 0.05-0.1 parts of silane coupling agent KH-550.

4. The seedling culture medium according to claim 3, characterized in that: The porous fiber matrix is ​​prepared by the following steps: rice husk and corn stalk are mixed and crushed to a particle size of ≤1.5 mm, immersed in a citric acid solution, the pH is adjusted to 4-5, ultrasonically treated at 55-60°C for 40-60 minutes, nano-silicon dioxide dispersion and silane coupling agent KH-550 are added for ultrasonic treatment for 10-30 minutes, centrifuged, washed with water to neutrality, and freeze-dried.

5. The seedling culture medium according to claim 4, characterized in that: The concentration of the citric acid solution is 0.5-1.0 mol / L.

6. The seedling culture medium according to claim 4, characterized in that: After adjusting the pH to 4-5, the ultrasonic treatment frequency is 35-40kHz; after adding the nano-silicon dioxide dispersion and the silane coupling agent KH-550, the ultrasonic treatment frequency is 30-40kHz.

7. The seedling culture medium according to claim 1, characterized in that: The raw material of the temperature-sensitive water-retaining layer is temperature-responsive gel particles; the raw materials of the temperature-responsive gel particles include, by mass: 8-15 parts of humus, 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 urea solution is 0.8-1.2 mol / L, and the concentration of calcium chloride solution is 0.1-0.5 mol / L.

8. The seedling culture medium according to claim 7, characterized in that: The temperature-responsive gel particles are prepared by the following steps: humus and wheat bran are added to urea solution, stirred at 70-80°C for 1-2 hours, cooled to 40°C, N-vinyl caprolactam, sodium alginate and photoinitiator are added in sequence under nitrogen protection, stirred evenly, calcium chloride solution is added dropwise, UV light is used for curing after complete addition, and the solution is dried.

9. The seedling culture medium according to claim 7, characterized in that: UV curing time is 40-90s, UV wavelength is 365nm, UV intensity is 70-90mW / cm 2 .

10. A process for preparing the seedling culture medium according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: laying a vermiculite particle layer, a first fiber matrix layer, a temperature-sensitive water-retaining layer and a second fiber matrix layer in order from bottom to top, rolling twice, each time for 1-1.5 minutes, and a rolling pressure of 0.8-1.0 MPa; and then irradiating and sterilizing twice, with an interval of 24-36 hours between the two irradiation sterilizations.

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