Preparation of green nano sulfur and application of green nano sulfur in prevention and control of litchi blackskin disease
By preparing green nano-sulfur and spraying it on litchi fruit, the problem of controlling litchi black skin disease has been solved, and the appearance and quality of the fruit have been improved, making it suitable for large-scale production.
Patent Information
- Application Number
- CN202510449047.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2025-08-12
AI Technical Summary
Litchi black skin disease is a physiological disorder caused by manganese toxicity. Current technologies are insufficient to effectively control it, affecting the appearance and economic value of the fruit.
A green nano-sulfur preparation method was adopted, in which litchi leaves were extracted by hydrothermal method, and nano-sulfur was prepared by reaction of sodium thiosulfate and hydrochloric acid. The nano-sulfur was then sprayed on litchi fruit to alleviate manganese stress and reduce the occurrence of black spot disease.
It significantly reduces the incidence and disease index of litchi black skin disease, improves fruit appearance, enhances fruit color and quality, and is simple to operate and environmentally friendly.
Smart Images
Figure CN120463156A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of litchi cultivation, and in particular to the preparation of green nano-sulfur and its application in preventing and controlling litchi black skin disease. Background Art
[0002] A new lychee fruit disease, black skin disease, has been reported in South China. It begins mid-fruit expansion, initially with a partial black or dark-brown discoloration of the mesocarp. This disease then gradually spreads to the mid- and outer pericarp. In severe cases, the outer pericarp can become largely black and brown, severely affecting the fruit's appearance and significantly reducing its selling price, or even destroying its commercial value. The disease has been reported in lychee varieties including Guiwei, Wuheli, Guanyinlu, Maguili, Jingganghongnuo, Lingfengnuo, Jizuili, and Fengshanhongdenglantern. It has been confirmed to be a physiological disease caused by manganese toxicity.
[0003] Sulfur is the fourth most important nutrient element after nitrogen, phosphorus and potassium. 2- Sulfur fertilizer is absorbed by plant roots in its natural form and transformed into organosulfur compounds such as cysteine, glutathione, and coenzyme A through a series of reactions within the plant. Glutathione and phytochelatin are important substances for heavy metal detoxification in plants, actively regulating plant defense systems and improving environmental tolerance. However, applying sulfur fertilizer to the soil can easily lead to soil acidification. Foliar spraying can address this issue, delivering nutrients directly to the target area. It offers the advantages of rapid onset, low dosage, and environmental friendliness.
[0004] Nanomaterials have large specific surface areas, small particle sizes, unique electronic motion states, and surface effects, and are widely used in agriculture, the environment, and food. Nanosulfur has the potential to resist biotic and abiotic stresses, enhance antioxidant defense systems, and act as a nanofertilizer, with broad application prospects in disease prevention and control, heavy metal remediation, and increasing crop yields. Nanosulfur materials synthesized from plant extracts have the advantages of simple operation, inexpensive raw materials, and biocompatibility. The active ingredients in the extracts (such as alcohols, phenols, and terpenes) play a key role in the dispersion, stabilization, and size control of sulfur particles.
[0005] Based on this, a green synthesis and biocompatible method for preparing nanosulfur and its application in preventing and controlling litchi black skin disease were proposed. Summary of the Invention
[0006] The main purpose of the present invention is to provide a method for preparing green nano-sulfur and its application in preventing and controlling litchi black skin disease. The green nano-sulfur prepared by the present invention is sprayed during the litchi fruit expansion period to alleviate the manganese stress suffered by the litchi, thereby reducing the occurrence of black skin disease and improving the appearance of the fruit.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a preparation of green nano-sulfur and its application in preventing and controlling litchi black skin disease, which specifically includes the following steps:
[0008] Step 1: Wash and crush fresh lychee leaves discarded from orchard pruning, extract them by hydrothermal method, and cool and filter them to obtain an extract;
[0009] Step 2: dissolving sodium thiosulfate in the litchi extract, adding hydrochloric acid dropwise, causing the sodium thiosulfate to undergo a disproportionation reaction to obtain a yellow precipitate;
[0010] Step 3: Centrifuge the yellow precipitate obtained in step 2, wash with ultrapure water, and vacuum dry to obtain a light yellow powder.
[0011] In step 1 of the green nano-sulfur preparation method, the mass ratio of litchi leaf powder to ultrapure water is 1:10-20.
[0012] Preferably, in step 1, the mass ratio of litchi leaf powder to ultrapure water is 1:10.
[0013] Preferably, in step 1, the temperature of the hydrothermal reaction is 90-100° C., and the time is 30-40 min.
[0014] Preferably, in step 1, the hydrothermal reaction is carried out at 100° C. and the reaction time is 30 min.
[0015] In step 2 of the green nano-sulfur preparation method, the mass ratio of sodium thiosulfate to hydrochloric acid is 1:4-2:1, the hydrochloric acid is added at a rate of 0.15-1.65 mL / min, and stirring is continued for 0-6 hours after the addition.
[0016] Preferably, in step 2, the mass ratio of sodium thiosulfate to hydrochloric acid is 2:1, the hydrochloric acid addition rate is 0.21 mL / min, and stirring is stopped immediately after the addition is completed and centrifugation is performed.
[0017] Preferably, in step 3, the vacuum drying temperature is 60-80° C., and the drying time is 2-5 h.
[0018] Preferably, in step 3, the vacuum drying temperature is 60° C. and the drying time is 2 h.
[0019] The present invention provides a green nano-sulfur obtained by any of the above methods for preparing the green nano-sulfur material.
[0020] The present invention also provides the use of green nano-sulfur in preventing and controlling black skin disease of litchi fruit.
[0021] Preferably, the solution prepared with the nano-sulfur is sprayed on the litchi during the fruit expansion period, once a week, for a total of 3-4 times.
[0022] Preferably, the nano-sulfur solution is sprayed at a concentration of 100-300 mg / L and a spraying rate of 400-800 mL / m 2 .
[0023] Preferably, the nano-sulfur is sprayed so that the surface of the fruit is fully wetted.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] 1. The main raw materials of the green nano-sulfur of the present invention are discarded lychee leaves and sodium thiosulfate, which are environmentally friendly, easily available, simple in preparation process, safe and controllable in reaction conditions, and suitable for large-scale production.
[0026] 2. The green nano-sulfur prepared in the present invention significantly reduces the incidence of litchi black skin disease, improves fruit color and quality, and the spraying operation is simple and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 (ac) are scanning electron microscope images of green nanosulfur at different magnifications; Figure 1 (d) is a transmission electron microscope image of green nanosulfur;
[0028] Figure 2 This is the XRD pattern of green nanosulfur;
[0029] Figure 3 This is the FT-IR spectrum of green nanosulfur;
[0030] Figure 4 The incidence and disease index of black skin disease in litchi fruits sprayed with green nanosulfur in Example 1;
[0031] Figure 5 is the phenolic content of the peel of dark-skinned and normal-skinned litchi fruits sprayed with green nanosulfur in Example 1;
[0032] Figure 6 The soluble solids, soluble sugars, titratable acid, and sugar-acid ratio of the dark-skinned and normal litchi fruits sprayed with green nanosulfur in Example 1 are shown;
[0033] Figure 7 The incidence and disease index of black skin disease on litchi leaves and fruits sprayed with green nanosulfur in Example 2;
[0034] Figure 8 The phenolic content of the dark-skinned and normal-skinned litchi leaves and fruits sprayed with green nanosulfur in Example 2;
[0035] Figure 9 The soluble solids, soluble sugars, titratable acid, and sugar-acid ratio of the dark-skinned and normal litchi leaves and fruits sprayed with green nanosulfur in Example 2; DETAILED DESCRIPTION
[0036] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.
[0037] Example 1
[0038] A method for preparing green nano-sulfur materials comprises the following steps:
[0039] Step 1: Wash and crush fresh lychee leaves discarded from orchard pruning, extract them by hydrothermal method, and cool and filter them to obtain an extract;
[0040] Step 2: dissolving sodium thiosulfate in the litchi extract, adding hydrochloric acid dropwise, causing the sodium thiosulfate to undergo a disproportionation reaction to obtain a yellow precipitate;
[0041] Step 3: Centrifuge the yellow precipitate obtained in step 2, wash with ultrapure water, and vacuum dry to obtain a light yellow powder.
[0042] Preferably, in step 1, the mass ratio of litchi leaf powder to ultrapure water is 1:10.
[0043] Preferably, in step 1, the hydrothermal reaction is carried out at 100° C. and the reaction time is 30 min.
[0044] Preferably, in step 2, the mass ratio of sodium thiosulfate to hydrochloric acid is 2:1, the hydrochloric acid is added at a rate of 0.21 mL / min, and stirring is stopped immediately after the addition is complete and centrifugation is performed.
[0045] Preferably, in step three, the vacuum drying temperature is 60° C. and the drying time is 2 h.
[0046] The nanosulfur synthesized in the example was used to carry out a test on the prevention and control of litchi black skin disease.
[0047] Before the experiment, the nano-sulfur powder was prepared into a solution (200 mg / L) and dispersed for later use.
[0048] The lychee trees required for the experiment were selected from Fengshan Red Lantern, located in the Baoguo Litchi Planting Base in Dongchong Town, Chengdong District, Shanwei City, Guangdong Province. The lychee planting specifications were 6*6m and the tree age was 35 years.
[0049] The experiment set up two treatments, the fruit was sprayed with nano-sulfur solution (experimental group) and the fruit was sprayed with water (control group), each treatment was repeated four times, and the spraying treatment was carried out during the fruit expansion period at a dosage of 400mL / m 2 Spray once a week for 3-4 times to fully wet all fruit surfaces.
[0050] After the fruits were ripe, all the fruits from each test tree were collected, sealed and placed in a foam box with ice packs, and promptly transported to the laboratory for processing and measurement of relevant indicators.
[0051] Characterization of Nanosulfur Synthesized from Litchi Leaf Extract
[0052] Green-synthesized nanosulfur particles are mostly rhombus-shaped and clearly defined. Transmission electron microscopy reveals that the structure is composed of multiple small particles agglomerated, with cavities between them. This suggests that nanosulfur synthesis involves a precipitation-aging process, and that particle size is affected by reaction time and the medium used. Lychee extract has the ability to disperse and stabilize sulfur, helping to regulate the size of the nanosulfur.
[0053] X-ray powder diffraction patterns are used to characterize the material's phase composition, crystal structure, and grain size. The green nanosulfur material is composed of S8, Fddd orthorhombic structure (JCPDS No. 24-0733), and the diffraction peaks at 25.06°, 25.83°, 26.70°, 27.69°, 28.65°, 28.93°, and 31.38° correspond to the (2 2 2), (0 2 6), (3 1 1), (2 06), (3 1 3), (1 3 5), and (0 4 4) crystal planes of sulfur, respectively.
[0054] Fourier transform infrared spectroscopy can analyze the chemical bonds, functional groups and molecular structure information of materials. The main functional groups of green nanosulfur materials include Ar-OH, -CO-NH-, -COOH, -CH2-, SS, and the characteristic absorption peaks include the stretching vibration of hydroxyl group (3399cm -1 ) and bending vibration (1383cm -1 ), NH stretching vibration of amide (3262cm -1 ), CN stretching vibration and NH bending vibration combined frequency region (1277cm -1 ) and the combined frequency region of CN bending vibration and NH bending vibration (1719-1524cm -1 ), the asymmetric and symmetric stretching vibrations of the CH of the alkyl group (2921, 2855 cm -1 ), stretching vibration of C=C of aromatic ring (1635-1447cm -1 ) and CH bending vibration (840cm -1 ), C=O stretching vibration of carboxylic acid (1719-1635cm -1 ) and CO(1115cm -1 ), SS stretching vibration (468 and 437cm -1 ) and CS stretching vibration (1115, 1072 and 660cm -1 This indicates that the elemental sulfur in the nanosulfur material forms a bond with the carbon component of the litchi leaf extract, and the material contains multiple active functional groups such as phenol, acid, amide, and aromatic ring.
[0055] Analysis on the incidence of litchi black skin disease
[0056] Fifty fruits were randomly selected from each replicate and classified according to whether they were infected with black skin. Diseased fruits were weighed, the skin removed, and the affected area separated from the healthy area. The black skin disease prevalence was calculated using the following formula: Disease prevalence = weight of black skin diseased fruit / (weight of black skin diseased fruit + weight of healthy fruit) * 100%; Disease index = weight of affected fruit skin / (weight of affected fruit skin + weight of healthy fruit skin) * 100%.
[0057] The incidence of black skin disease in litchi fruit in Experimental Example 1 is as follows: the incidence of black skin disease in the experimental trees sprayed with green nano-sulfur was 69.5%, and the disease index was 39.9%; the incidence of the control group was 82.8%, and the disease index was 47.6%. This shows that the treatment of spraying fruit with green nano-sulfur significantly reduced the incidence of black skin disease in litchi (P<0.05) ( Figure 4 ) and disease index, which decreased by 16.1% and 16.2% respectively.
[0058] Lychee fruit color
[0059] The color of lychee fruit is the result of the combined effects of multiple pigments, including color-producing anthocyanins and auxiliary color-producing flavanols, flavonols, and phenolic acids. Nine phenolic compounds were detected in lychee peel, among which the color-producing anthocyanins (cyanidin-3-glucoside and cyanidin-3-rutinoside) are the main compounds that cause the bright red phenotype of lychee peel ( Figure 5 ) The content of cyanidin-3-rutinoside was significantly higher in normal litchi fruits than in diseased ones. Treatment with green nanosulfur significantly increased the contents of cyanidin-3-glucoside and cyanidin-3-rutinoside (P<0.05), by 48.8% and 17.8%, respectively, effectively improving litchi fruit color. Ferulic acid, a phenolic acid with antioxidant activity, was also significantly increased by green nanosulfur treatment (by 64.3%), contributing to a certain degree of antioxidant capacity in the pericarp.
[0060] Lychee fruit quality
[0061] Flavor is an important indicator of litchi fruit quality and is related to the soluble solids, soluble sugars, titratable acid content, and sugar-acid ratio in the fruit. The content, type, and ratio of sugar and organic acids are key factors affecting the sweet and sour taste of the fruit, and flavor influences people's preference for the fruit, which in turn affects its economic value. Figure 6 As shown in the results, spraying green nanosulfur did not affect the soluble solids and soluble sugar content of litchi pulp, but significantly reduced the titratable acid content (by 24.5%), leading to a significant increase in the sugar-acid ratio by 20.3% (P < 0.05). Spraying green nanosulfur on fruit shows the potential to reduce titratable acidity and enhance flavor.
[0062] Example 2
[0063] A method for preparing green nano-sulfur materials comprises the following steps:
[0064] Step 1: Wash and crush fresh lychee leaves discarded from orchard pruning, extract them by hydrothermal method, and cool and filter them to obtain an extract;
[0065] Step 2: dissolving sodium thiosulfate in the litchi extract, adding hydrochloric acid dropwise, causing the sodium thiosulfate to undergo a disproportionation reaction to obtain a yellow precipitate;
[0066] Step 3: Centrifuge the yellow precipitate obtained in step 2, wash with ultrapure water, and vacuum dry to obtain a light yellow powder.
[0067] In step 1, the mass ratio of litchi leaf powder to ultrapure water is 1:10.
[0068] In step 1, the hydrothermal reaction temperature is 100° C. and the reaction time is 30 min.
[0069] In step 2, the mass ratio of sodium thiosulfate to hydrochloric acid is 2:1, the hydrochloric acid addition rate is 0.21 mL / min, and stirring is stopped immediately after the addition is completed and centrifugation is performed.
[0070] In step 3, the vacuum drying temperature is 60° C. and the drying time is 2 h.
[0071] The nanosulfur synthesized in the example was used to carry out a test on the prevention and control of litchi black skin disease.
[0072] The lychee trees required for the experiment were selected from Fengshan Red Lantern, located in the Baoguo Litchi Planting Base in Dongchong Town, Chengdong District, Shanwei City, Guangdong Province. The lychee planting specifications were 6*6m and the tree age was 35 years.
[0073] Before the experiment, the nano-sulfur powder was prepared into a solution (200 mg / L) and dispersed for later use.
[0074] The experiment set up two treatments: spraying the fruits and leaves with nanosulfur (experimental group) and spraying the fruits and leaves with water (control group). Each treatment was repeated four times. The spraying was carried out during the fruit expansion period at a dosage of 800 mL / m 2 The surface of all fruits and fruiting branches should be fully moistened and sprayed 3-4 times a week.
[0075] After the fruits were ripe, all the fruits from each test tree were collected, sealed and placed in a foam box with ice packs, and promptly transported to the laboratory for processing and measurement of relevant indicators.
[0076] Analysis on the incidence of litchi black skin disease
[0077] Fifty fruits were randomly selected from each replicate and classified based on whether they were infected with black skin. Diseased fruits were weighed, the skin removed, and the affected area separated from the healthy area. The black skin disease prevalence was calculated using the following formula: Incidence = Weight of black skin diseased fruit / (Weight of black skin diseased fruit + Weight of healthy fruit) * 100%; Disease index = Weight of affected fruit skin / (Weight of affected fruit skin + Weight of healthy fruit skin) * 100%.
[0078] The results showed that spraying fruits and leaves with green nanosulfur could significantly reduce the incidence and disease index of black skin disease in litchi (P<0.05). The incidence of black skin disease in the control group was 59.8%, while that in the experimental group was 43.8%, while the disease index dropped from 48.8% (control group) to 37.3% (treatment group) ( Figure 7 ).
[0079] Lychee fruit color
[0080] The effect of spraying green nanosulfur on fruits and leaves simultaneously on anthocyanin compounds in the peel was not significant ( Figure 8 ), only the flavonol quercetin-3-glucoside content increased significantly, by 54.9% (P < 0.05). Flavonols are one of the main flavonoids in plants and are often involved in oxidative stress responses, exhibiting free radical scavenging and antioxidant activities. Simultaneous spraying of lychee fruit and leaves had a modest effect on improving fruit color, but did enhance the antioxidant activity of the peel to some extent.
[0081] Lychee fruit quality
[0082] Spraying green nanosulfur on fruits and leaves did not affect the soluble solids content, but significantly increased the soluble sugar and titratable acid contents of litchi fruits ( Figure 9 ), with increases of 7.9% and 17.1% respectively (P<0.05). Due to the large increase in titratable acid content, the sugar-acid ratio of the green nanosulfur treatment was significantly lower than that of the control (a decrease of 12.9%), and the fruit flavor was sour.
[0083] In summary, field trials of spraying green nanosulfur during the litchi fruit expansion period showed that green nanosulfur can significantly reduce the incidence and disease index of litchi black skin disease; spraying the fruit can significantly increase the content of red anthocyanins in the peel and improve the fruit color; while spraying the fruit and leaves has no significant effect on the color of the litchi peel and has limited effect on improving the appearance of the fruit. On the other hand, spraying the fruit significantly reduces the titratable acid content, thereby increasing the sugar-acid ratio, making the fruit flavor sweeter; while spraying the fruit and leaves significantly increases the titratable acid and soluble sugar content, but the increase in titratable acid is greater than that of soluble sugar, resulting in a lower sugar-acid ratio and a sour fruit flavor. Therefore, based on the prevention and control of litchi black skin disease and the improvement of fruit color and quality, it is recommended to spray the fruit with green nanosulfur materials.
[0084] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing green nano-sulfur, characterized in that: The specific steps include: Step 1: Wash and crush fresh lychee leaves discarded from orchard pruning, extract them by hydrothermal method, and cool and filter them to obtain an extract; Step 2: dissolving sodium thiosulfate in the litchi extract, adding hydrochloric acid dropwise, causing the sodium thiosulfate to undergo a disproportionation reaction to obtain a yellow precipitate; Step 3: Centrifuge the yellow precipitate obtained in step 2, wash with ultrapure water, and vacuum dry to obtain a light yellow powder.
2. The method for preparing green nano-sulfur according to claim 1, wherein: In step 1, the mass ratio of litchi leaf powder to ultrapure water is 1:10-20.
3. The method for preparing green nano-sulfur according to claim 1, wherein: In step 1, the temperature of the hydrothermal reaction is 90-100° C. and the time is 30-40 minutes.
4. The method for preparing green nano-sulfur according to claim 1, characterized in that: In step 2, the mass ratio of sodium thiosulfate to hydrochloric acid is 1:4-2:1, the hydrochloric acid is added at a rate of 0.15-1.65 mL / min, and stirring is continued for 0-6 hours after the addition.
5. The method for preparing green nano-sulfur according to claim 1, characterized in that: The vacuum drying temperature in step 3 is 60-80° C., and the drying time is 2-5 h.
6. A green nano-sulfur, characterized in that: The green nano-sulfur material is obtained by the preparation method of any one of claims 1 to 5.
7. Use of the green nanosulfur as claimed in claim 6 in preventing and controlling black skin disease of litchi fruit.
8. The use according to claim 7, characterized in that During the fruit expansion period of litchi, the solution prepared with the nano-sulfur is sprayed on the litchi once a week for 3-4 times.
9. A use according to claim 8, characterized in that Each time the green nano-sulfur solution is sprayed, the concentration is 100-300 mg / L and the spraying amount is 400-800 mL / m 2 .
10. The use according to claim 8, characterized in that The spraying state is that the fruit surface is fully moistened.