Frequency spectrum film for helping plant growth and development and improving disease resistance

Abstract

The invention discloses a frequency spectrum thin film for helping plant growth and development and improving disease resistance, and particularly relates to the technical field of thin films, the frequency spectrum thin film comprises a temperature-sensitive polymer matrix, photosensitive nanoparticles and a frequency spectrum conversion material, is of a three-layer composite structure, can dynamically adjust the transmittance of 400-700nm wave bands according to environment temperature and illumination intensity, optimizes plant photosynthesis spectrums, and improves the disease resistance of plants. Meanwhile, the advantages of waste infrared light utilization, hydrophobicity, pollution resistance, disease resistance enhancement, biodegradability, accurate spectrum management and the like are achieved, and the processing method can guarantee uniform material dispersion, uniform film light transmission and high microbial inoculum survival rate. The defects of a traditional film in plant planting application are effectively overcome, and the film has important significance in promoting plant growth, improving crop quality and reducing environmental pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of thin films. More specifically, the present invention relates to a spectral thin film that helps plant growth and development and enhances disease resistance. Background Art

[0002] In modern agricultural production, plastic films are widely used in planting facilities such as greenhouses and play an important role in crop growth. However, traditional plastic films have relatively single functions and only have basic light transmission and heat preservation functions, making it difficult to meet the complex requirements of the light environment during the plant growth process. With the development of agricultural modernization, precise regulation of the plant growth environment has become the key to improving crop yield and quality.

[0003] On the one hand, light is the energy source for plant photosynthesis, and light of different wavelengths has different effects on plant growth and development. However, traditional films cannot effectively adjust the spectrum according to changes in environmental temperature and light intensity. In winter with low temperature and weak light, plants need more blue-violet light to promote photosynthesis, but traditional films cannot increase the transmittance of blue-violet light; in summer with high temperature and strong light, excessive strong light will cause photo-inhibition and photo-damage to plants, and traditional films also cannot enhance the transmittance of red light to optimize the light environment, limiting the growth potential of plants.

[0004] On the other hand, the high-temperature and high-humidity environment in greenhouses is prone to breeding various pathogenic bacteria, leading to frequent occurrence of plant diseases. Traditional films do not have antibacterial and bacteriostatic functions. In order to prevent and control diseases, growers often rely too much on chemical pesticides, which not only increases production costs but also causes problems such as excessive pesticide residues in agricultural products and environmental pollution.

[0005] In addition, most traditional plastic films are difficult to degrade and accumulate in the natural environment for a long time, causing serious damage to the soil structure and ecological environment. With the enhancement of environmental awareness, it is urgent to develop biodegradable thin film materials.

[0006] At present, although some functional films have emerged on the market, they generally have problems such as single function and unstable performance. For example, some films with spectral adjustment functions cannot simultaneously take into account antibacterial and degradation properties; the antibacterial effects of some antibacterial films are limited and have no promoting effect on plant growth. Therefore, it is of great practical significance to develop a spectral thin film that integrates multiple functions and can effectively help plant growth and development and enhance disease resistance. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides a spectral thin film that helps plant growth and development and enhances disease resistance to solve the problems raised in the above background art.

[0008] To achieve the above object, the present invention provides the following technical solution: A spectral thin film for helping plant growth and development and enhancing disease resistance, comprising a thermosensitive polymer matrix, photosensitive nanoparticles, and a spectral conversion material; the thermosensitive polymer matrix is a copolymer of poly(N-isopropylacrylamide) and polyethylene glycol, the photosensitive nanoparticles are cadmium selenide quantum dots, and the spectral conversion material includes zinc oxide / titanium oxide heterojunction nanowires; the thin film can dynamically adjust the transmittance in the 400-700 nm band according to the environmental temperature (15-45 °C) and light intensity (100-1000 μmol·m - 2·s - 1) Dynamically adjust the transmittance in the 400-700 nm band, increase the transmittance of blue-violet light (400-500 nm) by ≥30% under low temperature and weak light conditions, and enhance the transmittance of red light (600-700 nm) by ≥25% under high temperature and strong light conditions.

[0009] The phase change of the thermosensitive polymer with temperature change is used to adjust the pore size of the thin film; the photosensitive quantum dots adjust the light absorption characteristics through the surface plasmon resonance effect; the heterojunction nanowires convert ultraviolet light into visible light, so as to adaptively optimize the photosynthesis spectrum of plants, reduce the stress of high temperature and strong light, and improve the photosynthetic efficiency in weak light environments.

[0010] Preferably, the spectral conversion material further contains 0.1-0.5 wt% of rare earth doped upconversion material, and the rare earth is erbium / ytterbium co-doped sodium yttrium fluoride (NaYF4:Er 3+ ,Yb 3+ ), which can convert 980 nm near-infrared light into 660 nm red light.

[0011] The rare earth ions absorb near-infrared light and emit visible light through a multi-photon process, thereby utilizing the waste infrared light resources, supplementing plant light signals at night, and prolonging the photoperiod effect.

[0012] Preferably, the thin film is a three-layer composite structure, including:

[0013] a) An outer hydrophobic and anti-fouling layer (thickness 50-100 μm), containing perfluoroalkyl acrylate;

[0014] b) A middle dynamic adjustment layer (thickness 200-300 μm), containing the components described in claim 1;

[0015] c) An inner bioactive layer (thickness 100-150 μm), loaded with Bacillus subtilis spores (106-108 CFU / g).

[0016] The hydrophobic layer prevents dust and preserves the light transmittance, and the bioactive layer releases antagonistic bacteria to inhibit pathogenic bacteria, which can reduce the light attenuation caused by surface contamination and simultaneously enhance the systemic disease resistance of plants.

[0017] Preferably, the thermosensitive polymer matrix further contains 0.05-0.2 wt% carbon quantum dots, the surfaces of which are modified with carboxyl and amino groups, and the average particle size is ≤5 nm.

[0018] By using carbon quantum dots as a light-trapping agent to enhance the response sensitivity of the photosensitive material, the spectral regulation response speed under low-light conditions can be increased by >20%.

[0019] Preferably, the film is biodegradable, and the matrix material comprises a blend of polylactic acid (PLA) and polyhydroxyalkanoate (PHA) (mass ratio 7:3), and the degradation period is 12-18 months.

[0020] Through the hydrolysis and chain scission of PLA / PHA under the action of soil microorganisms, the environmental pollution problem of traditional plastic films can be solved, and the degradation products can promote the increase of soil organic matter.

[0021] Preferably, a micro photovoltaic sensor array (spacing 10 cm×10 cm) is provided on the surface of the film, and the sensor is electrically connected to a liquid crystal dimming layer embedded in the film, and the transmission band can be automatically adjusted according to the real-time spectral data.

[0022] By detecting the light intensity / spectrum with a photovoltaic sensor and feedback controlling the change of the liquid crystal molecular orientation to change the transmittance, precise spectral management can be achieved, and the utilization rate of photosynthetically active radiation (PAR) can be increased by ≥35%.

[0023] Preferably, the bioactive layer further contains 0.1-0.3 wt% chitosan / nano silver composite, the particle size of the nano silver is 20-50 nm, and the loading amount is 1-3 mg / g.

[0024] By enhancing the film adhesion with chitosan and the broad-spectrum antibacterial property of nano silver, the fungal diseases can be synergistically inhibited, and the control effect on Botrytis cinerea is ≥85%.

[0025] The processing method of the above-mentioned spectral film for helping plant growth and development and improving disease resistance includes the following steps:

[0026] (1) Mix the thermosensitive polymer, photosensitive quantum dots, and heterojunction nanowires in supercritical CO2 (pressure 15 MPa, temperature 50 °C), the mixing time is 2-4 hours, and then depressurize to normal pressure, and carry out aging treatment at a temperature of 30-40 °C for 1-2 hours;

[0027] (2) Prepare a three-layer composite structure by electrospinning, the electric field strength is 3 kV / cm, the receiving distance is 20 cm, the concentration of the spinning solution is controlled at 10-15 wt%, and the spinning time is 3-5 hours;

[0028] (3) The bioactive layer is loaded with the microbial agent by spray drying method, with an inlet temperature of 120 °C, an outlet temperature of 60 °C, a spray pressure of 0.2 - 0.4 MPa, and a mass ratio of the microbial agent to the carrier solution of 1:(5 - 10). After loading the microbial agent, the bioactive layer is post-treated for 2 - 3 days in an environment with a humidity of 50 - 70% and a temperature of 25 - 30 °C.

[0029] The dispersibility of the material is improved by supercritical fluid, and the structural porosity is optimized by electrospinning, so that the light transmittance uniformity of the film (standard deviation ≤ 2%) and the survival rate of the microbial agent > 95%.

[0030] The beneficial effects of the present invention are as follows:

[0031] 1. By adjusting the film pore size with the temperature-sensitive polymer according to the temperature change, adjusting the light absorption characteristics with the photosensitive quantum dots, and converting ultraviolet light into visible light with the heterojunction nanowires, the film can dynamically adjust the transmittance in the 400 - 700 nm band according to the environmental temperature and light intensity, increase the transmittance of blue-violet light by ≥ 30% under low temperature and weak light, enhance the transmittance of red light by ≥ 25% under high temperature and strong light, optimize the photosynthesis spectrum of plants, reduce the stress of high temperature and strong light, and improve the photosynthetic efficiency in weak light environment.

[0032] 2. The rare earth-doped upconversion material in the spectral conversion material can convert 980 nm near-infrared light into 660 nm red light, utilize the waste infrared light resources, supplement the plant light signal at night, and extend the photoperiod effect.

[0033] 3. The outer hydrophobic and anti-fouling layer contains perfluoroalkyl acrylate, which can prevent dust and maintain the light transmittance; the inner bioactive layer is loaded with Bacillus subtilis spores, which release antagonistic bacteria to inhibit pathogenic bacteria, reduce the light attenuation caused by surface contamination, and simultaneously enhance the systemic disease resistance of plants.

[0034] 4. The 0.05 - 0.2 wt% carbon quantum dots contained in the temperature-sensitive polymer matrix, with carboxyl and amino groups on the surface and an average particle size ≤ 5 nm, act as a light trapping agent to enhance the response sensitivity of the photosensitive material, so that the spectral regulation response speed under weak light conditions is increased by > 20%.

[0035] 5. The film matrix material is a blend of polylactic acid (PLA) and polyhydroxyalkanoate (PHA), which is biodegradable, with a degradation period of 12 - 18 months. It hydrolyzes and breaks the chain under the action of soil microorganisms, solves the environmental pollution problem of traditional plastic films, and the degradation products can also promote the increase of soil organic matter.

[0036] 6. The micro photovoltaic sensor array on the film surface is electrically connected to the embedded liquid crystal dimming layer, and automatically adjusts the transmission band according to the real-time spectral data, realizing precise spectral management, so that the photosynthetically active radiation utilization rate is increased by ≥ 35%.

[0037] 7. The bioactive layer contains 0.1-0.3wt% chitosan / nanosilver complex, with nanosilver particles of 20-50nm and a loading of 1-3mg / g. Chitosan enhances membrane adhesion, while nanosilver has a broad spectrum of antibacterial properties, synergistically inhibiting fungal diseases and achieving ≥85% protection against gray mold.

[0038] 8. In the processing method, supercritical fluid improves the dispersion of materials, electrospinning optimizes the structural porosity, and makes the film transmittance uniform; spray drying combined with post-treatment ensures that the survival rate of the bacterial agent is greater than 95%. DETAILED DESCRIPTION

[0039] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0040] Example 1

[0041] Thin film preparation

[0042] Mix materials: Accurately weigh poly (N-isopropylacrylamide) and polyethylene glycol copolymer as the thermosensitive polymer matrix, cadmium selenide quantum dots as the photosensitive nanoparticles, and zinc oxide / titanium oxide heterojunction nanowires as the spectrum conversion material. Mix in a supercritical CO2 environment at 15 MPa and 50°C for 2 hours, then reduce the pressure to ambient and age at 30°C for 1 hour.

[0043] Electrospinning composite structure: The mixed materials were prepared into a 10wt% spinning solution, and a three-layer composite structure was prepared using an electrospinning process. The electric field strength was set at 3kV / cm, the receiving distance was 20cm, and the spinning time was 3 hours. The outer hydrophobic and antifouling layer, containing perfluoroalkyl acrylate, was spun first; the middle dynamic regulation layer, containing the mixed materials, was spun next; and finally, the inner bioactive layer was spun.

[0044] Loading: Prepare a Bacillus subtilis spore inoculum at a mass ratio of 1:5 between inoculum and carrier solution. Load the inoculum onto the bioactive layer using spray drying at an inlet temperature of 120°C, an outlet temperature of 60°C, and a spray pressure of 0.2 MPa. After loading, post-treat the bioactive layer at 50% humidity and 25°C for 2 days.

[0045] Performance Testing

[0046] Spectral regulation performance: In a simulated low temperature and weak light environment (temperature 15°C, light intensity 100 μmol·m - 2 s - 1) Using a spectrum analyzer, the transmittance of 400-500nm blue-violet light increased by 32%; in a simulated high temperature and strong light environment (temperature 45°C, light intensity 1000μmol·m- 2·s - (1) Under the following conditions, the transmittance of red light at 600 - 700 nm is increased by 26%, meeting the design requirements.

[0047] Disease resistance performance: When this film is covered on a small greenhouse for growing cucumbers and compared with ordinary films, the probability of cucumbers being infected with fungal diseases during the planting period is significantly reduced, and the control effect on gray mold reaches 86%.

[0048] Light transmittance uniformity: The transmittance of different positions of the film is detected by an optical instrument, and the calculated standard deviation is 1.8%, meeting the standard of light transmittance uniformity (standard deviation ≤ 2%).

[0049] Example 2

[0050] Film preparation

[0051] Mixed materials: Weigh the thermosensitive polymer matrix, photosensitive nanoparticles and spectral conversion materials in proportion, add them into supercritical CO2, mix them for 3 hours under the conditions of a pressure of 15 MPa and a temperature of 50 °C, and then carry out a curing treatment at 35 °C for 1.5 hours after reducing the pressure to normal pressure.

[0052] Electrospinning to prepare a composite structure: The mixed materials are made into a spinning solution with a concentration of 12 wt%, and electrospinning is carried out at an electric field strength of 3 kV / cm and a receiving distance of 20 cm for 4 hours to prepare a three - layer composite structure in sequence.

[0053] Loading the microbial agent: The microbial agent and the carrier solution are formulated into a Bacillus subtilis spore microbial agent according to a mass ratio of 1:8, and it is loaded onto the bioactive layer by spray drying, with an inlet temperature of 120 °C, an outlet temperature of 60 °C, and a spray pressure of 0.3 MPa. After loading, it is post - treated for 2.5 days in an environment with a humidity of 60% and a temperature of 28 °C.

[0054] Performance testing

[0055] Spectral adjustment performance: After testing, in a low - temperature and low - light environment, the transmittance of blue - violet light is increased by 33%; in a high - temperature and high - light environment, the transmittance of red light is increased by 27%.

[0056] Light capture and response speed: In a low - light environment, when comparing the films with and without carbon quantum dots, it is found that the spectral adjustment response speed of this film containing carbon quantum dots is increased by 23%.

[0057] Biodegradation performance: When the film is buried in the soil, after 14 months, the mass of the film is reduced by about 75%, and the degradation products increase the organic matter content of the soil.

[0058] Example 3

[0059] Film preparation

[0060] Mixed materials: Accurately measure each material, mix them in supercritical CO2 at 15 MPa and 50 °C for 4 hours, and then carry out a curing treatment at 40 °C for 2 hours after reducing the pressure to atmospheric pressure.

[0061] Electrospinning to prepare a composite structure: Prepare a 15 wt% spinning solution, and carry out electrospinning for 5 hours at an electric field strength of 3 kV / cm and a receiving distance of 20 cm to prepare a three-layer composite structure film.

[0062] Loading the microbial agent: Prepare a Bacillus subtilis spore microbial agent with a mass ratio of the microbial agent to the carrier solution of 1:10. When loading the microbial agent by spray drying, the inlet temperature is 120 °C, the outlet temperature is 60 °C, and the spray pressure is 0.4 MPa. After loading, carry out a post-treatment for 3 days in an environment with a humidity of 70% and a temperature of 30 °C.

[0063] Performance testing

[0064] Spectral regulation performance: Test in a simulated environment of low temperature and weak light and high temperature and strong light. The transmittance of blue-violet light increases by 35%, and the transmittance of red light increases by 28%.

[0065] Photosynthetically active radiation utilization rate: In the actual planting environment, in the area using this film, the utilization rate of photosynthetically active radiation (PAR) has increased by 38%.

[0066] Survival rate of the microbial agent: Detect the microbial agent in the bioactive layer, and the survival rate reaches 96%, ensuring the continuous functioning of the bioactive layer.

[0067] Example 4

[0068] Film preparation

[0069] Mixed materials: Weigh each raw material, mix them in supercritical CO2 at 15 MPa and 50 °C for 2.5 hours, and then carry out a curing treatment at 32 °C for 1.2 hours under atmospheric pressure.

[0070] Electrospinning to prepare a composite structure: Prepare a 11 wt% spinning solution from the mixed materials, and carry out electrospinning for 3.5 hours at an electric field strength of 3 kV / cm and a receiving distance of 20 cm to prepare a three-layer composite structure.

[0071] Loading the microbial agent: The mass ratio of the microbial agent to the carrier solution is 1:6. Load the microbial agent by spray drying, with an inlet temperature of 120 °C, an outlet temperature of 60 °C, and a spray pressure of 0.25 MPa. After loading, carry out a post-treatment for 2.2 days in an environment with a humidity of 55% and a temperature of 26 °C.

[0072] Performance testing

[0073] Spectral regulation performance: In the simulated environment, when the temperature is low and the light is weak, the transmittance of blue-violet light increases by 31%, and when the temperature is high and the light is strong, the transmittance of red light increases by 25%.

[0074] Comprehensive performance: When using this film in the greenhouse for growing tomatoes, the growth trend of tomato plants is good, the fruit yield and quality are both improved, and at the same time, the amount of pesticide used is reduced.

[0075] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A spectrum thin film for assisting plant growth and development and enhancing disease resistance, characterized in that It includes a temperature-sensitive polymer matrix, photosensitive nanoparticles, and a spectral conversion material; the temperature-sensitive polymer matrix is a copolymer of poly(N-isopropylacrylamide) and polyethylene glycol, the photosensitive nanoparticles are cadmium selenide quantum dots, and the spectral conversion material includes zinc oxide / titanium oxide heterojunction nanowires.

2. The spectrum thin film for assisting plant growth and development and enhancing disease resistance ability according to claim 1, wherein The spectral conversion material further contains 0.1-0.5 wt% of a rare-earth doped upconversion material, and the rare earth is erbium / ytterbium co-doped sodium yttrium fluoride, which is used to convert 980 nm near-infrared light into 660 nm red light.

3. The spectrum thin film for assisting plant growth and development and enhancing disease resistance ability according to claim 1, wherein The thin film is a three-layer composite structure, including: a) An outer hydrophobic and anti-fouling layer containing perfluoroalkyl acrylate; b) A middle dynamic regulation layer containing a temperature-sensitive polymer matrix, photosensitive nanoparticles, and a spectral conversion material; c) An inner bioactive layer loaded with Bacillus subtilis spores.

4. A spectrum thin film for assisting plant growth and development and enhancing disease resistance ability according to claim 1, characterized in that, The temperature-sensitive polymer matrix further contains 0.05-0.2 wt% of carbon quantum dots, the surfaces of which are modified with carboxyl and amino groups, and the average particle size is ≤5 nm.

5. The spectrum thin film for assisting plant growth and development and enhancing disease resistance ability according to claim 1, wherein The thin film is biodegradable, and the matrix material contains a blend of polylactic acid and polyhydroxyalkanoate with a mass ratio of 7:

3.

6. The spectrum thin film for assisting plant growth and development and enhancing disease resistance ability according to claim 1, wherein, A micro photovoltaic sensor array (spacing 10 cm×10 cm) is provided on the surface of the thin film, and the sensor is electrically connected to a liquid crystal dimming layer embedded in the thin film, and the transmission band can be automatically adjusted according to the real-time spectral data.

7. A spectrum thin film for assisting plant growth and development and enhancing disease resistance ability according to claim 3, characterized in that, The bioactive layer further contains 0.1-0.3 wt% of a chitosan / nano-silver composite, the particle size of the nano-silver is 20-50 nm, and the loading amount is 1-3 mg / g.

8. A processing method of a spectrum thin film for assisting plant growth and development and enhancing disease resistance according to any one of claims 1-7, characterized in that, It includes the following steps: (1) Mix the temperature-sensitive polymer, photosensitive quantum dots, and heterojunction nanowires in supercritical CO2 at a pressure of 15 MPa and a temperature of 50 °C for 2-4 hours, and then reduce the pressure to atmospheric pressure and carry out a curing treatment at a temperature of 30-40 °C for 1-2 hours; (2) Prepare a three-layer composite structure by electrospinning, with an electric field strength of 3 kV / cm, a receiving distance of 20 cm, the concentration of the spinning solution controlled at 10-15 wt%, and the spinning time of 3-5 hours; (3) The bioactive layer is loaded with the microbial agent by spray drying, with an inlet temperature of 120 °C, an outlet temperature of 60 °C, a spray pressure of 0.2-0.4 MPa, and the mass ratio of the microbial agent to the carrier solution of 1:(5-10). After loading the microbial agent, the bioactive layer is post-treated in an environment with a humidity of 50-70% and a temperature of 25-30 °C for 2-3 days.