CN114605991A

CN114605991A - Berberis pruinosa carbon dot, light conversion film, preparation method and application thereof

Info

Publication number: CN114605991A
Application number: CN202210295015.XA
Authority: CN
Inventors: 于洪梅; 邓书平; 侯憧; 王志有; 朱秀慧
Original assignee: University of Science and Technology Liaoning USTL; Yingkou Institute of Technology
Current assignee: University of Science and Technology Liaoning USTL; Yingkou Institute of Technology
Priority date: 2022-03-24
Filing date: 2022-03-24
Publication date: 2022-06-10
Anticipated expiration: 2042-03-24
Also published as: CN114605991B

Abstract

The invention belongs to the technical field of light conversion materials, and discloses a berberis pruinosa carbon dot, a light conversion film, and a preparation method and application thereof. Wherein the preparation of the berberis pruinosa carbon dots comprises the following steps: the berberis pruinosa berberis thunb is pretreated to obtain leaf juice, the leaf juice, ethylenediamine and water are mixed and react, and the reaction product is sequentially centrifuged, filtered, dialyzed, evaporated and freeze-dried to obtain the berberis pruinosa berberis thunb carbon dots. The berberis pruinosa carbon dots are used as a light conversion agent to prepare a light conversion film which is applied to plant growth, can improve the photosynthesis of plants, accelerate the growth and development of the plants and increase the crop yield.

Description

Berberis pruinosa carbon dot, light conversion film, preparation method and application thereof

Technical Field

The invention relates to the technical field of light conversion materials, in particular to a berberis pruinosa carbon dot and a light conversion film as well as a preparation method and application thereof.

Background

Light is a basic environmental element for plant growth and development, and sunlight comprises ultraviolet light, visible light and near infrared light. Wherein, the blue-violet light (400-480 nm) and the red orange light (600-700 nm) can be absorbed by the pigments such as chlorophyll a, chlorophyll b and the like, and the photosynthesis of the plant is enhanced to promote the growth and development of the plant. In addition, although the ultraviolet radiation can transmit and accumulate energy, the microorganisms are inactivated, and the aim of sterilization is fulfilled; but also damages plant tissues and induces plant diseases. Therefore, it is desirable to design and synthesize materials for improving the photosynthesis efficiency of plants by converting part of the uv light, which is not beneficial to plant growth, into blue light which can be absorbed and utilized by chlorophyll a, b.

The light conversion film is a composite material which converts ultraviolet light into blue-violet light required by photosynthesis of plants by adding a light conversion agent, improves the light transmission quality and improves the effective light utilization rate. Utilize and change the membrane and can convert part ultraviolet ray into the bluish violet light that can utilize for plant photosynthesis, the photosynthesis of reinforcing plant promotes the increase of crop output and the promotion of quality. The development of the agricultural light conversion film starts at the end of the 80 s, the PE film developed by the vinca physics of Chinese academy of sciences is developed earlier in China for ginseng cultivation, and the agricultural light conversion film has the effects of 5-7 days earlier in seedling emergence, improving the saponin content of ginseng roots by 24 percent and improving the saponin content of stem leaves by 35 percent. The light conversion film is non-toxic, high in hydrophilicity, rich in surface functional groups, stable in fluorescence, fast in proton transfer capacity and excellent in light capturing capacity, so that the preparation and application of the light conversion film have important significance for agricultural production. However, the application effect of the light conversion film is mainly influenced by the performance of the light conversion agent, and at present, most light conversion agents are organic fluorescent pigments and metal organic complexes, and have the problems of poor light stability, fast light conversion attenuation, low light transmittance and the like.

The carbon dots, a fluorescent carbon nano material, has the advantages of low toxicity, small pollution, stable photoluminescence, quick proton conductivity, excellent light capture capacity and the like, and the carbon dots are used as a light conversion agent to prepare the light conversion film, so that the photosynthesis of plants can be promoted, and the carbon dots have important significance for improving the overall performance of the film. In addition, compared with an organic carbon source, the biomass-based carbon dot has the advantages of simple synthesis process, low cost, corresponding emission spectrum to plant synthesis spectrum, good dispersibility and the like. However, there are only few reports on biomass-based carbon dot light conversion films and their preparation and application.

Therefore, how to prepare the light conversion film by using the biomass-based carbon dots becomes a problem which needs to be solved by the technical personnel in the field.

Disclosure of Invention

Compared with the common light conversion agent, the Berberis pruinosa carbon dots are used as the light conversion agent to prepare the light conversion film which is applied to the growth of plants, so that the photosynthesis of the plants can be improved, the growth and development of the plants are accelerated, and the yield of the crops is increased.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of Berberis pruinosa carbon dots comprises the following steps:

the berberis pruinosa berberis thunb is pretreated to obtain leaf juice, the leaf juice, ethylenediamine and water are mixed and react, and the reaction product is sequentially centrifuged, filtered, dialyzed, evaporated and freeze-dried to obtain the berberis pruinosa berberis thunb carbon dots;

the volume ratio of the leaf juice to the ethylenediamine to the water is 2-5: 0.3-0.5: 8-12; the concentration of the leaf juice is 0.005-0.125 g/mL.

Further, the reaction temperature is 80-90 ℃, and the reaction time is 5-20 min;

the rotating speed of the centrifugation is 8000-12000 r/min, and the time is 8-15 min;

the aperture of the filter membrane used for filtering is 0.2-0.3 mu m;

the cut-off molecular weight of the dialysis is 500-2000 Da, and the time is 40-60 h;

the temperature of the freeze drying is-60 to-70 ℃, and the time is 24 to 36 hours.

The invention provides the berberis pruinosa carbon dots prepared by the preparation method.

The invention provides a light conversion film containing the berberis purpurea carbon dots, which comprises the following components in mass ratio of 300-800: 1-30 of a membrane substrate and berberis pruinosa carbon dots;

the thickness of the light conversion film is 5-15 nm.

Further, the film substrate is sodium carboxymethyl cellulose or chitosan.

The invention provides a preparation method of the light conversion film, which comprises the following steps:

mixing the membrane substrate, the berberis pruinosa carbon dots and water to obtain a mixed solution, and performing ultrasonic degassing and vacuum drying on the mixed solution to obtain a light conversion membrane;

the mass-volume ratio of the membrane substrate, the berberis pruinosa carbon dots and the water is 300-800 mg: 1-30 mg: 25-40 mL.

Further, the mixing time is 0.5-2 h, the ultrasonic degassing power is 250-400W, and the ultrasonic degassing time is 25-35 min.

Further, the vacuum degree of the vacuum drying is 8000-9000 Pa, the temperature is 30-50 ℃, and the time is 20-30 hours.

The invention also provides application of the light conversion film in plant growth.

According to the technical scheme, compared with the prior art, the invention has the following beneficial effects:

1. the carbon dots of berberis pruinosa pall prepared by the invention adopt biomass as a carbon source, the raw materials are cheap and easy to obtain, and the method is green and sustainable, and is suitable for mass production;

2. the carbon dots of berberis pruinosa as a light conversion agent, the sodium carboxymethylcellulose and the chitosan as a light conversion film substrate, the carbon dots of berberis pruinosa are uniformly dispersed in the film substrate, and the carbon dots of berberis pruinosa have the light conversion effect by adding the carbon dots of berberis pruinosa;

3. the light conversion film prepared by the invention can improve the utilization rate of sunlight and enhance the photosynthetic capacity of plants, and can convert part of ultraviolet light which is not beneficial to the growth of plants into blue light which can be absorbed and utilized by chlorophyll a and b, thereby promoting the net photosynthetic rate of crops and increasing the agricultural yield;

4. the light conversion film prepared by the invention can be excited by high-energy ultraviolet light and emit low-energy blue light, and the energy difference generated in the process can be released in the form of heat energy, so that the internal temperature is increased, and the growth and development of crops are promoted;

5. the light conversion film prepared by the invention can promote the growth and development of crops and increase the yield, and the growth rate of the crops covered by the light conversion film is higher than that of the common film due to the increase of the internal temperature and the improvement of the photosynthetic capacity of the crops.

Drawings

FIG. 1 is a TEM image (a) and a particle size distribution chart (b) of carbon dots of Berberis pruinosa prepared in example 1 of the present invention;

FIG. 2 is a PL spectrum (b) and a fluorescence spectrum (c) of the maximum excitation spectrum and the maximum emission spectrum (a) of the carbon dots of Berberis pruinosa prepared in example 1 of the present invention under different excitations (340nm, 360nm, 380nm, 400nm, 420nm, 400 nm);

FIG. 3 is a fluorescence spectrum of light conversion films prepared in examples 4 to 8 and containing Berberis pruinosa C-points and carboxymethylcellulose sodium (0.2%, 0.4%, 0.8%, 1%, 5%) in different mass ratios;

FIG. 4 is a fluorescence spectrum of light conversion films prepared in examples 9 to 15 and containing Berberis pruinosa carbon dots and chitosan (0.2%, 0.4%, 0.6%, 0.8%, 1%, 3%, 5%) in different mass ratios;

FIG. 5 (a) is a graph showing the transmission spectra of light conversion films prepared in examples 4 to 8 and containing Berberis pruinosa carbon dots and carboxymethylcellulose sodium (0.2%, 0.4%, 0.8%, 1%, 5%) at different mass ratios; (b) transmission spectra of light conversion films prepared for examples 9-15 containing berberis pruinosa carbon dots and chitosan (0.2%, 0.4%, 0.6%, 0.8%, 1%, 3%, 5%) at different mass ratios;

FIG. 6 is a graph showing the growth process of heart-shaped grass according to experiment 1 of the present invention;

FIG. 7 is a graph showing the growth process of heart-shaped grass according to experiment 2 of the present invention.

Detailed Description

The invention provides a preparation method of berberis pruinosa carbon dots, which comprises the following steps:

the berberis pruinosa berberis thunb is pretreated to obtain leaf juice, the leaf juice, ethylenediamine and water are mixed and react, and the reaction product is sequentially centrifuged, filtered, dialyzed, evaporated and freeze-dried to obtain the berberis pruinosa berberis thunb carbon dots.

In the invention, the volume ratio of the leaf juice to the ethylenediamine to the water is 2-5: 0.3-0.5: 8-12, preferably 3-4: 0.35-0.45: 9 to 11, and more preferably 3.5: 0.4: 10; the concentration of the leaf juice is 0.005-0.125 g/mL, preferably 0.01-0.1 g/mL, and more preferably 0.02-0.05 g/mL.

In the invention, the method for obtaining the leaf juice from the berberis pruinosa by pretreatment comprises the following specific steps: the berberis pruinosa is cleaned and then soaked in water for 30-40 minutes, and then taken out and dried until no water drops exist. Weighing 5-25 g of leaves, adding 200-1000 mL of water, squeezing into leaf juice, pouring out the leaf juice, filtering with filter paper, and then performing suction filtration with a sand core to obtain the leaf juice of the mauve liquid; the preferable technical scheme of the pre-treatment of berberis purpurea comprises the following steps: cleaning berberis pruinosa, soaking in water for 30 minutes, taking out, and drying in the air until no water drops exist. Weighing 10g of leaves, adding 400mL of water, squeezing into leaf juice, pouring out the leaf juice, filtering with filter paper, and performing suction filtration with a sand core to obtain the leaf juice of the mauve liquid.

In the invention, the reaction temperature is 80-90 ℃, preferably 83-86 ℃, and more preferably 84-85 ℃; the time is 5-20 min, preferably 8-15 min, and more preferably 10-12 min;

the centrifugal rotating speed is 8000-12000 r/min, preferably 9000-11000 r/min, and further preferably 10000 r/min; the time is 8-15 min, preferably 9-12 min, and further preferably 10 min;

the aperture of the filter membrane used for filtration is 0.18-0.45 μm, preferably 0.20-0.28 μm, and further preferably 0.22-0.25 μm;

the cut-off molecular weight of the dialysis is 500-2000 Da, preferably 800-1500 Da, and further preferably 1000-1200 Da; the time is 40-60 h, preferably 45-55 h, and further preferably 48-50 h;

the temperature of the freeze drying is-60 to-70 ℃, preferably-62 to-68 ℃, and more preferably-64 to-66 ℃; the time is 24-36 h, preferably 28-35 h, and more preferably 30-32 h.

The invention provides a light conversion film containing the berberis purpurea carbon dots, which comprises the following components in mass ratio of 300-800: 1-30 of a membrane substrate and berberis purpurea carbon points, wherein the mass ratio of the membrane substrate to the berberis purpurea carbon points is preferably 350-600: 2 to 20, more preferably 400 to 500: 4-10;

the thickness of the light conversion film is 5-15 nm, preferably 6-12 nm, and more preferably 8-12 nm.

In the present invention, the film substrate is sodium carboxymethyl cellulose or chitosan, preferably chitosan.

In the invention, carbon dots in the light conversion film emit visible light with the peak wavelength of 440-495 nm under the excitation of light with the wavelength of 340-400 nm. In addition, after the carboxymethyl cellulose membrane and the chitosan membrane are added with the carbon dots in the pure membrane substrate, the prepared light conversion membrane improves the mechanical property and the thermal stability.

in the invention, the mass-volume ratio of the membrane substrate, the berberis pruinosa carbon dots and water is 300-800 mg: 1-30 mg: 25-40 mL, preferably 350-600 mg: 2-20 mg: 28-35 mL, more preferably 400-500 mg: 3-10 mg: 30-32 mL.

In the invention, the mixing time is 0.5-2 h, preferably 0.8-1.5 h, and more preferably 1-1.2 h; the power of ultrasonic degassing is 250-400W, preferably 280-350W, and further preferably 300-320W; the time is 25 to 35min, preferably 28 to 32min, and more preferably 30 min.

In the invention, the vacuum degree of the vacuum drying is 8000-9000 Pa, the temperature is 30-50 ℃, preferably 32-34 ℃, and more preferably 33 ℃; the time is 20-30 h, preferably 22-28 h, and more preferably 24-26 h.

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Preparation of carbon dots of berberis pruinosa

Example 1

Cleaning berberis pruinosa, soaking in water for 30 minutes, taking out, and drying in the air until no water drops exist. Weighing 5g of leaves, adding 200mL of water, squeezing to obtain leaf juice, pouring out the leaf juice, filtering with filter paper, and performing suction filtration with a sand core to obtain the leaf juice (0.025g/mL) of purple red liquid. Transferring 2mL of leaf juice, 300 mu L of ethylenediamine and 10mL of deionized water, sequentially adding into a 250mL conical flask, uniformly mixing, placing into a microwave oven, heating at 85 ℃ for 5min, taking out, adding 10mL of deionized water, uniformly mixing, and centrifuging at 10000r/min by using a high-speed centrifuge for 8 min. After removal, the supernatant was filtered through a disposable filter (0.22 μm) to obtain a purified brown-yellow carbon dot solution. The purification was carried out by dialysis in a 500Da dialysis bag at room temperature for 48 hours, during which the water was changed at 3-hour intervals. Removing solvent by rotary evaporation, placing into a culture dish, freezing at (-20 deg.C, 24 hr), and freeze drying in a freeze drier at (-60 deg.C) for 24 hr to obtain brown carbon dot solid powder of Berberis pruinosa.

As can be seen from figure 1, the obtained berberis pruinosa carbon dots are quasi-spherical, the average particle size is 3.82 +/-0.75 nm, the lattice spacing is 0.22nm, and the crystal faces are close to the crystal faces of graphite (100);

as can be seen from FIG. 2, the carbon spot of Berberis pruinosa has a maximum excitation wavelength of 400nm and a maximum emission wavelength of 495nm, and has an excitation wavelength dependence, and when the excitation wavelength is from 340 to 440nm, the emission wavelength is red-shifted from 440nm to 520 nm.

Example 2

Cleaning berberis pruinosa, soaking in water for 30 minutes, taking out, and drying in the air until no water drops exist. Weighing 10g of leaves, adding 400mL of water, squeezing to obtain leaf juice, pouring out the leaf juice, filtering with filter paper, and performing suction filtration with a sand core to obtain the leaf juice (0.025g/mL) of purple red liquid. Transferring 3mL of leaf juice, 400 mu L of ethylenediamine and 10mL of deionized water, sequentially adding into a 250mL conical flask, uniformly mixing, placing into a microwave oven, heating at 80 ℃ for 10min, taking out, adding 10mL of deionized water, uniformly mixing, and centrifuging at 10000r/min by using a high-speed centrifuge for 10 min. After removal, the supernatant was filtered through a disposable filter (0.22 μm) to obtain a purified brown-yellow carbon dot solution. The purification was carried out by dialysis in a 1000Da dialysis bag at room temperature for 48 hours, during which the water was changed at 3-hour intervals. Removing solvent by rotary evaporation, placing into a culture dish, freezing in a freezer (-20 deg.C, 24 hr), freeze drying in a freeze drier (-65 deg.C) for 30 hr to obtain brown carbon dot solid powder of Berberis pruinosa.

Example 3

Cleaning berberis pruinosa, soaking in water for 30 minutes, taking out, and drying in the air until no water drops exist. Weighing 15g of leaves, adding 800mL of water, squeezing to obtain leaf juice, pouring out the leaf juice, filtering with filter paper, and performing suction filtration with a sand core to obtain the leaf juice (0.01875g/mL) of purple red liquid. Transferring 4mL of leaf juice, 450 mu L of ethylenediamine and 10mL of deionized water, sequentially adding the leaf juice, the 450 mu L of ethylenediamine and the 10mL of deionized water into a 250mL conical flask, uniformly mixing, placing the mixture into a microwave oven, heating the mixture at 90 ℃ for 15min, then taking the mixture out, adding 10mL of deionized water, uniformly mixing, and centrifuging the mixture for 12min at the rotating speed of 10000r/min by using a high-speed centrifuge. After removal, the supernatant was filtered through a disposable filter (0.22 μm) to obtain a purified brown-yellow carbon dot solution. The purification was carried out by dialysis against 1500Da dialysis bags at room temperature for 48 hours, during which the water was changed at 3-hour intervals. Removing solvent by rotary evaporation, placing into a culture dish, freezing in a freezer (-20 deg.C, 24 hr), freeze drying in a freeze drier (-70 deg.C) for 36 hr to obtain brown carbon dot solid powder of Berberis pruinosa.

Preparation of light conversion film

Example 4

Mixing 0.5g of sodium carboxymethylcellulose with 1mg of carbon dots of berberis pruinosa as in example 1, adding 30mL of deionized water, mixing and stirring for 1 hour to obtain a mixed solution of a light yellow viscous liquid, placing the mixed solution into an ultrasonic cleaning machine, performing ultrasonic degassing for 30min at the power of 300W, finally quickly pouring the mixed solution into a culture dish, and performing vacuum drying (the vacuum degree is 8000Pa) at 40 ℃ for 24 hours to obtain the light conversion film. The carbon point of berberis pruinosa in the light conversion film is 0.2 percent of the mass of the sodium carboxymethylcellulose.

Example 5

The procedure of example 4 was followed, except that 2mg of berberis purpurea carbon dots were added to obtain a light conversion film in which the berberis purpurea carbon dots were 0.4% by mass of the sodium carboxymethylcellulose.

Example 6

The procedure of example 4 was followed, except that 4mg of berberis purpurea carbon dots were added to obtain a light conversion film in which the berberis purpurea carbon dots were 0.8% by mass of the sodium carboxymethylcellulose.

Example 7

The procedure of example 4 was followed, except that in this example, 5mg of berberis pruinosa carbon dots were added, and the obtained light conversion film had berberis pruinosa carbon dots of 1% by mass of sodium carboxymethylcellulose.

Example 8

The procedure of example 4 was followed, except that 25mg of berberis pruinosa carbon dots were added to obtain a light conversion film containing 5% by mass of berberis pruinosa carbon dots based on the mass of sodium carboxymethylcellulose.

FIG. 3 is a fluorescence spectrum of light conversion films prepared in examples 4 to 8 and containing Berberis pruinosa C-points and carboxymethylcellulose sodium (0.2%, 0.4%, 0.8%, 1%, 5%) in different mass ratios. As can be seen from fig. 3, the light conversion films containing berberis amurensis carbon dots and carboxymethylcellulose sodium (0.2%, 0.4%, 0.8%, 1%, 5%) with different mass ratios showed fluorescence spectra in the entire blue region under uv excitation.

Example 9

0.5g of chitosan is mixed with 1mg of carbon dots of berberis pruinosa in example 1, 30mL of deionized water is added for mixing and stirring for 1 hour to obtain a mixed solution of a light yellow viscous liquid, the mixed solution is placed into an ultrasonic cleaning machine for ultrasonic degassing for 30min under the power of 320W, finally the mixed solution is quickly poured into a culture dish, and vacuum drying is carried out for 24 hours at the temperature of 40 ℃ (the vacuum degree is 8500Pa) to obtain the light conversion film. The carbon point of berberis pruinosa in the light conversion film is 0.2 percent of the mass of the chitosan.

Example 10

The procedure of example 9 was followed, except that 2mg of Berberis pruinosa carbon dots were added to obtain a light conversion film containing 0.4% of the weight of the chitosan.

Example 11

The procedure of example 9 was followed, except that 3mg of berberis pruinosa carbon dots were added to obtain a light conversion film containing 0.6% of berberis pruinosa carbon dots based on the mass of chitosan.

Example 12

The procedure of example 9 was repeated, except that 4mg of Berberis pruinosa carbon dots were added to obtain a light conversion film containing 0.8% of the weight of chitosan.

Example 13

The procedure of example 9 was followed, except that in this example, 5mg of berberis pruinosa carbon dots were added, and the obtained light conversion film had berberis pruinosa carbon dots of 1% by mass of chitosan.

Example 14

The procedure of example 9 was followed, except that 15mg of berberis pruinosa carbon dots were added to obtain a light conversion film in which the berberis pruinosa carbon dots accounted for 3% by mass of chitosan.

Example 15

The procedure of example 9 was followed, except that 25mg of Berberis pruinosa carbon dots were added to obtain a light conversion film containing 5% of the Berberis pruinosa carbon dots based on the weight of chitosan.

FIG. 4 is a fluorescence spectrum of light conversion films prepared in examples 9 to 15 and containing Berberis pruinosa carbon dots and chitosan (0.2%, 0.4%, 0.6%, 0.8%, 1%, 3%, 5%) in different mass ratios. As can be seen from fig. 4, the light conversion films containing berberis purpurea carbon dots and chitosan (0.2%, 0.4%, 0.6%, 0.8%, 1%, 3%, 5%) in different mass ratios showed fluorescence spectra in the entire blue region under uv excitation.

FIG. 5 (a) is a graph showing the transmission spectra of light conversion films prepared in examples 4 to 8 and containing Berberis pruinosa carbon dots and carboxymethylcellulose sodium (0.2%, 0.4%, 0.8%, 1%, 5%) at different mass ratios; (b) transmission spectra of light conversion films prepared for examples 9-15 and containing berberis pruinosa carbon dots and chitosan (0.2%, 0.4%, 0.6%, 0.8%, 1%, 3%, 5%) in different mass ratios. As can be seen from FIG. 5, the two types of light conversion films have low light transmittance in the ultraviolet region (200-400nm), and can convert ultraviolet light into blue light, thereby facilitating the application of the light conversion films in organisms and simultaneously reducing the damage of the ultraviolet light to plants.

Performance test

The experiment is carried out in the laboratory simulation warmhouse booth, and the size of simulation warmhouse is: 40cm long, 25cm wide and 1000cm area². The test crop is heart-shaped grass, and the seeds of the test crop are purchased from the internet. And (3) coating a film after field planting, evenly dividing the simulation greenhouse into six areas, and separating each area by using a partition plate to obtain relatively independent experimental space. 100 healthy crop seeds are planted in each area, the water and fertilizer management means is carried out according to the conventional method, the test greenhouse film is divided into two groups to be tested in sequence, one group is a carbon point/chitosan light conversion film with the concentration of 1%, 3% and 5%, the other group is a carbon point/chitosan light conversion film with the concentration of 0.2%, 0.4% and 0.6%, and the light conversion films are spliced and covered at equal intervals.

Test 1: the left side of the test field is covered with light conversion films with carbon dot content of 1%, 3% and 5%, the right side is used for comparison (a comparison group 1 corresponds to the light conversion film with carbon dot content of 1%, a comparison group 2 corresponds to the light conversion film with carbon dot content of 3%, a comparison group 3 corresponds to the light conversion film with carbon dot content of 5%), a blank film is covered, recording is started from the seedling stage of crops, the plant growth condition is continuously monitored and photographed, and the growth process of heart-shaped grass is shown in a figure 1. Finally, 15 crops are selected in each experimental environment to measure the height of the plants, and the average value is taken and recorded as the following table 1.

Table 1: influence of light conversion film with carbon dot content of 1%, 3% and 5% on crop growth

Light conversion film (carbon dot content)	Number of germinated grains	Percentage of germination (%)	Average height of plant (cm)
				1％	45	45％	3.8
3％	50	50％	3.9
				5％	55	55％	4.5
Control group 1	39	39％	2.7
				Control group 2	32	32％	2.8
Control group 3	34	34％	3.2

From table 1 and fig. 6, the germination rates of the crops cultivated by covering the light conversion film with the carbon point content of 1%, 3% and 5% are respectively improved by 15%, 56% and 61%; the growth rate is respectively improved by 40 percent, 39 percent and 40 percent. The soil temperature can affect the photosynthesis in various ways such as the absorption of nutrient components of plant roots, the chlorophyll content of leaves, water metabolism, poison accumulation and the like, which shows that the light conversion film prepared by the invention can improve the utilization rate of sunlight and enhance the photosynthetic capacity of plants. The light conversion film can convert partial ultraviolet light which is not beneficial to plant growth into blue light which can be absorbed and utilized by chlorophyll a and b, so that the net photosynthetic rate of crops is promoted, and the agricultural yield is increased.

Test 2: the left side of the test field is covered with a light conversion film, the right side is used for comparison (a comparison group 1 corresponds to the light conversion film with the carbon point content of 0.2 percent, a comparison group 2 corresponds to the light conversion film with the carbon point content of 0.6 percent, a comparison group 3 corresponds to the light conversion film with the carbon point content of 0.6 percent), blank film-free covering is carried out, recording is started from the seedling stage of crops, the plant growth condition is continuously monitored and photographed, and the growth process of heart-shaped grass is shown in figure 2. Finally, 15 crops were selected for each experimental environment and the plant height was measured, averaged and recorded as in table 2 below.

Table 2: the light conversion film with the carbon point content of 0.2%, 0.4% and 0.6% has the influence on the growth and development of crops

As can be seen from table 2 and fig. 7, the germination rate of the no-film control group was low due to adverse effect of winter temperature on plant growth. The light conversion film prepared by the invention has longer ultraviolet light conversion efficiency duration time, has a warming effect, promotes chlorophyll accumulation to enhance plant growth, shortens crop development time, and promotes crop early maturity and yield increase.

In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The preparation method of the berberis pruinosa carbon dots is characterized by comprising the following steps:

2. The preparation method according to claim 1, wherein the reaction temperature is 80-90 ℃ and the reaction time is 5-20 min;

the aperture of the filter membrane used for filtering is 0.2-0.3 mu m;

3. A Berberis pruinosa carbon dot prepared by the preparation method of claim 1 or 2.

4. A light conversion film containing berberis pruinosa carbon dots as claimed in claim 3, wherein the light conversion film comprises the following components in a mass ratio of 300-800: 1-30 of a membrane substrate and berberis pruinosa carbon dots;

the thickness of the light conversion film is 5-15 nm.

5. The light conversion film according to claim 4, wherein the film substrate is sodium carboxymethyl cellulose or chitosan.

6. A method for producing a light conversion film according to claim 4 or 5, comprising the steps of:

7. The method for preparing a light conversion film according to claim 6, wherein the mixing time is 0.5 to 2 hours, the ultrasonic degassing power is 250 to 400W, and the ultrasonic degassing time is 25 to 35 min.

8. The method for producing a light conversion film according to claim 6 or 7, wherein the vacuum degree of the vacuum drying is 8000 to 9000Pa, the temperature is 30 to 50 ℃, and the time is 20 to 30 hours.

9. Use of the light conversion film according to claim 4 or 5 for plant growth.