A light conversion material that can be directly sprayed on leaves, and a preparation method and application thereof

Abstract

The application provides a light conversion material which can be directly sprayed on leaves, and a preparation method and application thereof. The light conversion material which can be directly sprayed on leaves comprises the following raw materials in parts by weight: agar 0.1-2 parts, water 20-30 parts, epichlorohydrin 2-10 parts, and rhodamine B 0.1-1 part. The application solves the problem of photobleaching of rhodamine B under light, solves the problem of high preparation cost and complex process of the light conversion material, and solves the problem that the light conversion material cannot be directly sprayed on leaves in the form of a uniform solution. The raw materials used in the application are cheap and easy to obtain, the process is simple, and the cost is low. The obtained light conversion material does not solidify at room temperature, is stable and uniform, can be directly sprayed, and can ensure that the light conversion material is uniformly sprayed on the surface of leaves. The light conversion material can convert green light into red and orange light which can be absorbed and utilized by plant leaves, effectively improves photosynthesis, and significantly improves the yield and quality of crops.

Description

Technical Field

[0001] This invention relates to a light-converting material that can be directly sprayed on leaves, its preparation method and application, belonging to the field of light-converting material technology. Background Technology

[0002] Research on light conversion has been quite active in recent years. Converting light into wavelengths beneficial to photosynthesis is of great significance for the development of high-tech agriculture. Agricultural plastic light-converting films can convert harmful or useless ultraviolet and green light in sunlight into red and blue light, which are essential for plant photosynthesis, and have gradually become a research hotspot. Researchers at home and abroad have successfully prepared light-converting films doped with fluorescent dyes and rare-earth organic complexes using PET, PVC, and PVA films as substrates. However, the small molecular size and poor compatibility with the base resin of greenhouse films cause leakage of the light-converting material within the film, affecting the light conversion effect. Furthermore, the complex and costly preparation processes of existing light-converting materials, requiring integration with the base resin during greenhouse film manufacturing, greatly limit their application in agriculture.

[0003] Therefore, developing light-converting materials that can be directly sprayed on leaves plays a crucial role in greenhouse vegetable production during the spring and winter months when sunlight is insufficient, and is of great significance to the development of high-tech agriculture in my country. Chinese patent document CN110278860A discloses a nano-light-converting method for leaf surfaces that promotes photosynthesis in bean sprouts. The preparation method specifically includes the following steps: preparing sol-gel silica using an oil bath reflux method; preparing hexagonal NaYF4:Yb,Er upconversion nanoparticles using an oil bath reflux and hydrothermal method; preparing carbon dots (CDs) using a hydrothermal method; and combining the sol-gel silica, carbon dots, and NaYF4:Yb,Er by mechanical stirring, followed by washing and drying to obtain a NaYF4:Yb,Er / carbon dot nanocomposite light-converting material. The nanocomposite luminescent material obtained by this patent is formulated into a suspension and sprayed onto the surface of bean sprout leaves, achieving light conversion on the leaf surface (absorbing near-infrared light and emitting red light), thereby promoting the photosynthetic rate of bean sprouts. However, the preparation process and required raw materials and equipment for the NaYF4:Yb,Er / carbon dot nanocomposite light-converting material in this invention patent are quite complicated. It requires the separate preparation of NaYF4:Yb,Er nanoparticles, silica sol, and carbon dots. Furthermore, the preparation of NaYF4:Yb,Er nanoparticles involves boiling reflux, high-temperature reaction, and multiple centrifugation processes, while the preparation of carbon dots also requires high-temperature reaction and centrifugation. This results in high investment in raw materials, equipment, and energy consumption. Additionally, the invention uses rare earth elements as the central ion, which are expensive. Moreover, the final product of this invention is a solid NaYF4:Yb,Er / carbon dot nanocomposite luminescent material, which needs to be ground into particles and then mixed with water to form a suspension for use. The nanoparticles are prone to agglomeration and precipitation in water, making it impossible to guarantee the stability and uniformity of the suspension during spraying, thus hindering the uniform spraying of the light-converting material onto the leaf surface. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a light-converting material that can be directly sprayed on leaves, along with its preparation method and application. This invention solves the problem of photobleaching of the commonly used organic light-converting material Rhodamine B under light irradiation; it also solves the problems of high preparation costs, complex processes, and the inability to form a homogeneous solution for direct foliar spraying. The raw materials used in this invention are inexpensive and readily available, the process is simple, and the cost is low; the resulting light-converting material does not solidify at room temperature, is stable and homogeneous, and can be directly sprayed, ensuring uniform spraying onto the leaf surface; the light-converting material of this invention can convert green light into red-orange light that can be absorbed and utilized by plant leaves, effectively improving photosynthesis and significantly increasing crop yield and quality.

[0005] The technical solution of the present invention is as follows:

[0006] A light-converting material that can be directly sprayed on leaves is prepared from the following raw materials in parts by weight: 0.1-2 parts agar, 20-30 parts water, 2-10 parts epichlorohydrin, and 0.1-1 parts rhodamine B.

[0007] According to a preferred embodiment of the present invention, the light-converting material that can be directly sprayed on the leaves is prepared from the following raw materials in parts by weight: 0.1-0.5 parts agar, 22-26 parts water, 5-9 parts epichlorohydrin, and 0.1-0.2 parts rhodamine B.

[0008] Preferably, the light-converting material that can be directly sprayed on the leaves is prepared from the following raw materials in parts by weight: 0.3 parts agar, 24 parts water, 7 parts epichlorohydrin, and 0.15 parts rhodamine B.

[0009] The preparation method of the above-mentioned light-converting material that can be directly sprayed on leaves includes the following steps:

[0010] Agar and epichlorohydrin were fully dispersed in water and reacted to obtain activated agar; Rhodamine B was added and reacted to obtain a light-converting material that could be directly sprayed on leaves.

[0011] According to a preferred embodiment of the present invention, the reaction temperature of agar and epichlorohydrin is 60-100°C, and the reaction time is 1-5 h; more preferably, the reaction temperature is 80°C, and the reaction time is 3 h. The hydroxyl groups in agar undergo a substitution reaction with the chlorine groups of epichlorohydrin, thereby introducing active epoxy groups into the molecular structure of agar.

[0012] According to a preferred embodiment of the present invention, the reaction temperature after adding Rhodamine B is 60-100°C, and the reaction time is 1-5 h; more preferably, the reaction temperature is 80°C, and the reaction time is 3 h. The epoxy groups in the activated agar undergo a grafting reaction with the carboxyl groups of Rhodamine B.

[0013] The above-mentioned light-converting materials that can be directly sprayed on the leaves can be applied directly or after dilution to the crop leaves to convert the green light in sunlight into red-orange light that can be absorbed and utilized by the plant leaves.

[0014] The technical features and beneficial effects of this invention are as follows:

[0015] 1. This invention uses inexpensive agar as a matrix. The agar is activated with epichlorohydrin, introducing active epoxy groups into the agar molecular structure, preventing solidification at room temperature after melting. Then, Rhodamine B is introduced into the agar molecular structure, ultimately preparing the light-converting material. The raw materials used in this invention are inexpensive and readily available, the process is simple, it does not require strict control of reaction conditions, and it does not require complex reaction equipment, resulting in low cost.

[0016] 2. A fatal flaw of the organic dye rhodamine B is its susceptibility to oxidation and decomposition under prolonged sunlight exposure. Under high-intensity excitation light, the fluorescence intensity of rhodamine B gradually weakens, leading to photobleaching. This invention effectively overcomes these problems through chemical modification of rhodamine B, significantly improving its resistance to photobleaching. The resulting light-converting material effectively converts green light into red-orange light that can be absorbed and utilized by plant leaves, and can stably maintain this effect for a long period.

[0017] 3. This invention solves the problem that light-converting materials cannot be water-soluble to form a homogeneous solution for direct foliar spraying. The light-converting material obtained by this invention does not solidify at room temperature and is stable and homogeneous, allowing for direct spraying and ensuring uniform application to the leaf surface. Simultaneously, its adhesive properties allow the material to adhere well to the leaf surface during foliar spraying, reducing losses such as droplet slippage. This light-converting material converts green light into red-orange light that can be absorbed and utilized by plant leaves, significantly enhancing photosynthesis, significantly increasing plant height, fresh weight, and dry weight, and improving crop yield and quality. Attached Figure Description

[0018] Figure 1 The fluorescence intensity of the Rhodamine B solution and the optically convertible material solution prepared in Example 1 of this invention changes over time.

[0019] Figure 2 These are the infrared spectra of agar and the light-converting material prepared in Example 1 of this invention;

[0020] Figure 3 This is a graph showing the photosynthetic rate, plant height, fresh weight, and dry weight of chili seedlings under different treatments in Experiment Example 3.

[0021] Figure 4 This is a graph showing the photosynthetic rate, plant height, fresh weight, and dry weight of maize seedlings under different treatments in Experiment Example 3. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments.

[0023] In addition, unless otherwise specified, all materials used in the following embodiments and comparative examples are commercially available, and all methods used are conventional methods in the art.

[0024] Example 1

[0025] A light-converting material that can be directly sprayed on leaves is prepared from the following raw materials in parts by weight: 0.3g agar, 24g water, 7g epichlorohydrin, and 0.15g rhodamine B.

[0026] The preparation method of the above-mentioned light-converting material that can be directly sprayed on leaves includes the following steps:

[0027] (1) Activation of agar: Dissolve 0.3g of agar in 3g of distilled water, and mix 7g of epichlorohydrin with 21g of distilled water; mix the above solutions and stir continuously at 80°C for 3h with a magnetic stirrer. The hydroxyl groups in the agar and the chlorine groups of epichlorohydrin undergo a substitution reaction, thereby introducing active epoxy groups onto the agar to obtain activated agar.

[0028] (2) Dissolve 0.15g of Rhodamine B in activated agar and stir continuously at 80℃ for 3h to obtain a light-converting material that can be directly sprayed on the leaves.

[0029] Example 2

[0030] A light-converting material that can be directly sprayed on leaves is prepared from the following raw materials in parts by weight: 0.1g agar, 20g water, 2g epichlorohydrin, and 0.1g rhodamine B.

[0031] The preparation method of the above-mentioned light-converting material that can be directly sprayed on leaves includes the following steps:

[0032] (1) Activation of agar: Dissolve 0.1g of agar in 3g of distilled water, and mix 2g of epichlorohydrin with 17g of distilled water; mix the above solutions and stir continuously at 80°C for 3h with a magnetic stirrer. The hydroxyl groups in the agar and the chlorine groups of epichlorohydrin undergo a substitution reaction, thereby introducing active epoxy groups onto the agar to obtain activated agar.

[0033] (2) Dissolve 0.1g of Rhodamine B in activated agar and stir continuously at 80℃ for 3h to obtain a light-converting material that can be directly sprayed on the leaves.

[0034] Example 3

[0035] A light-converting material that can be directly sprayed on leaves is prepared from the following raw materials in parts by weight: 2g agar, 30g water, 10g epichlorohydrin, and 1g rhodamine B.

[0036] The preparation method of the above-mentioned light-converting material that can be directly sprayed on leaves includes the following steps:

[0037] (1) Activation of agar: Dissolve 2g of agar in 3g of distilled water, and mix 10g of epichlorohydrin with 27g of distilled water; mix the above solutions and stir continuously at 80°C for 3h with a magnetic stirrer. The hydroxyl groups in the agar and the chlorine groups of epichlorohydrin undergo a substitution reaction, thereby introducing active epoxy groups onto the agar to obtain activated agar.

[0038] (2) Dissolve 1g of Rhodamine B in activated agar and stir continuously at 80°C for 3 hours to obtain a light-converting material that can be directly sprayed on the leaves.

[0039] Example 4

[0040] A light-converting material that can be directly sprayed on leaves is prepared from the following raw materials in parts by weight: 0.1g agar, 22g water, 5g epichlorohydrin, and 0.1g rhodamine B.

[0041] The preparation method of the above-mentioned light-converting material that can be directly sprayed on leaves includes the following steps:

[0042] (1) Activation of agar: Dissolve 0.1g of agar in 3g of distilled water, and mix 5g of epichlorohydrin with 19g of distilled water; mix the above solutions and stir continuously at 80°C for 3h with a magnetic stirrer. The hydroxyl groups in the agar and the chlorine groups of epichlorohydrin undergo a substitution reaction, thereby introducing active epoxy groups onto the agar to obtain activated agar.

[0043] (2) Dissolve 0.1g of Rhodamine B in activated agar and stir continuously at 80℃ for 3h to obtain a light-converting material that can be directly sprayed on the leaves.

[0044] Example 5

[0045] A light-converting material that can be directly sprayed on leaves is prepared from the following raw materials in parts by weight: 0.5g agar, 26g water, 9g epichlorohydrin, and 0.2g rhodamine B.

[0046] The preparation method of the above-mentioned light-converting material that can be directly sprayed on leaves includes the following steps:

[0047] (1) Activation of agar: Dissolve 0.5g of agar in 3g of distilled water, and mix 9g of epichlorohydrin with 23g of distilled water; mix the above solutions and stir continuously at 80°C for 3h with a magnetic stirrer. The hydroxyl groups in the agar and the chlorine groups of epichlorohydrin undergo a substitution reaction, thereby introducing active epoxy groups onto the agar to obtain activated agar.

[0048] (2) Dissolve 0.2g of Rhodamine B in activated agar and stir continuously at 80℃ for 3h to obtain a light-converting material that can be directly sprayed on the leaves.

[0049] Experimental Example 1

[0050] Accurately weigh 0.001 g of Rhodamine B and transfer it to a 100 mL volumetric flask, then dissolve it in distilled water to prepare a 0.01 g / L Rhodamine B solution. Accurately pipette 2 mL of the light-converting material prepared in Example 1 into a volumetric flask, and dissolve it in distilled water to prepare a light-converting material solution with a Rhodamine B concentration of 0.01 g / L. Place the prepared solution under a light intensity of 800 μmol·m⁻². -2 ·s -1 Irradiated under a white LED light source, samples were taken every 10 hours, and the fluorescence intensity of the Rhodamine B solution and the light-converting material solution was measured using a fluorescence spectrophotometer. Rhodamine B or the light-converting material was excited by green light to produce red light, with an excitation wavelength of 530 nm and an emission wavelength of 620 nm selected. During detection, both the fluorescence excitation and emission slits were 5 nm wide, and a high voltage was chosen.

[0051] like Figure 1 As shown in the results, the fluorescence intensity of the pure Rhodamine B solution decreased rapidly within 80 hours, indicating photobleaching. The fluorescence intensity of the light-converting material prepared in this invention showed only a slight change, with no significant decrease. This result demonstrates that grafting Rhodamine B with agar can significantly improve the photobleaching resistance of Rhodamine B, ensuring the light-converting ability of the light-converting material prepared in this invention. Therefore, the preparation of the Rhodamine B-grafted light-converting material is significant.

[0052] Experimental Example 2

[0053] To determine the grafting reaction between Rhodamine B and agarose, the present invention performed infrared spectroscopy analysis on agarose alone and on the light-converting material synthesized by the method in Example 1. Fourier transform infrared spectroscopy was used for infrared detection, and the spectral range was recorded as 400-4000 cm⁻¹. -1 .

[0054] from Figure 2 It can be seen that the agar is at 3439.23 cm. -1 It exhibits hydroxyl vibration at 2876.53 cm⁻¹ -1 It exhibits stretching vibrations of carbon-hydrogen bonds, at 1638.76 cm⁻¹. -1 It exhibits stretching vibrations of the carbon-carbon double bond, at 1388.71 cm⁻¹. -1 It exhibits bending vibrations of carbon-hydrogen bonds. For the modified agar, at 2876.53 cm⁻¹... -1 and 1388.71cm -1The peak weakens because the proportion of carbon-hydrogen bonds decreases after grafting Rhodamine B, resulting in a decrease in the amount absorbed relative to the overall proportion. Meanwhile, at 2356.39 cm⁻¹... -1 An additional peak appears, representing the asymmetric stretching vibration of the cumulative double bond, which represents the cumulative double bond in Rhodamine B. This proves that Rhodamine B has been chemically bonded to agar.

[0055] Experimental Example 3

[0056] 1. The light-converting material prepared by the method in Example 1 of this invention is applied to promote photosynthesis in chili peppers:

[0057] Pepper seedlings that had grown for 21 days were placed in sunlight for cultivation. The light-converting material prepared according to the method in Example 1 was sprayed evenly on the leaves once every 7 days, with 10 ml sprayed on each seedling until the leaves dripped. The spraying treatment lasted for 5 weeks. The treatment sprayed with water served as the control (CK).

[0058] Chili seedlings sprayed with the light-converting material of this invention showed the best growth. The photosynthetic rate, plant height, fresh weight, and dry weight of chili seedlings under different treatments were measured, and the data are as follows: Figure 3 As shown, when the light-converting material solution was sprayed, the net photosynthetic rate increased by 31.2% compared with the control CK, and the plant height, fresh weight and dry weight of pepper seedlings increased by 49.4%, 32.2% and 58% respectively, all of which reached a significant level.

[0059] 2. The light-converting material prepared by the method in Example 1 of this invention is applied to promote maize photosynthesis:

[0060] Corn seedlings that had grown for 14 days were placed in sunlight for cultivation. The light-converting material prepared according to the method in Example 1 was sprayed evenly on the leaves once every 7 days, with 10 ml sprayed on each seedling until the leaves dripped. The spraying treatment lasted for 3 weeks. The treatment sprayed with water served as the control (CK).

[0061] Corn seedlings sprayed with the light-converting material of this invention showed the best growth. The photosynthetic rate, plant height, fresh weight, and dry weight of corn seedlings under different treatments were measured, and the data are as follows: Figure 4 As shown, when the light-converting material solution was sprayed, the net photosynthetic rate increased by 34.6% compared with the control CK, and the plant height, fresh weight and dry weight of maize seedlings increased by 37.2%, 37.9% and 43.3% respectively, all of which reached a significant level.

Claims

1. Use of a light conversion material which can be applied directly by foliar spraying, characterized in that, The light conversion material can be directly sprayed on the leaves of crops to convert green light in sunlight into red-orange light which can be absorbed by plant leaves. The light conversion material which can be directly sprayed on the leaves comprises the following raw materials by weight: agar 0.1-0.5 parts, water 22-26 parts, epichlorohydrin 5-9 parts, and rhodamine B 0.1-0.2 parts. The preparation method of the light conversion material which can be directly sprayed on the leaves comprises the following steps: dispersing agar and epichlorohydrin in water to obtain activated agar; and adding rhodamine B to obtain the light conversion material which can be directly sprayed on the leaves.

2. Use of a light conversion material according to claim 1, which is directly foliarly sprayable, characterized in that, The light conversion material which can be directly sprayed on the leaves comprises the following raw materials by weight: agar 0.3 parts, water 24 parts, epichlorohydrin 7 parts, and rhodamine B 0.15 parts.

3. Use of the light-transmitting material according to claim 1, which is directly sprayed on the leaves, characterized in that, The reaction temperature of agar and epichlorohydrin is 60-100 DEG C, and the reaction time is 1-5 h.

4. The use of the light-transmissive material according to claim 1, which is directly sprayed on the leaves, characterized in that, The reaction temperature of agar and epichlorohydrin is 60-100 DEG C, and the reaction time is 1-5 h.

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