A low-residue selective fruit thinning chemical composition for fruit trees and a method for preparing the same

Abstract

The application belongs to the field of plant growth regulators, and discloses a low-residue selective fruit tree chemical thinning composition and a preparation method thereof.The composition comprises, in percentage by mass, 6-12% of active ingredients, 3-8% of environmentally-friendly additives, 1-3% of degradation promoters, and 77-89% of solvents.The active ingredients are a compound of 6-benzylaminopurine and ammonium acetate, the environmentally-friendly additives are a mixture of sodium docusate and methyl oleate, the degradation promoters include L-ascorbyl palmitate, a fatty acid ester derivative, polyaspartic acid or nano titanium dioxide, and the solvents are a mixture of deionized water and ethanol.The composition has the characteristics of good thinning effect, strong selectivity, low residue and no drug hazards, and is suitable for various fruit trees.The preparation method has the advantages of simple process, low energy consumption, no harmful by-products, suitability for large-scale production and promotion, and meeting the needs of green agriculture and pollution-free fruit planting.

Description

Technical Field

[0001] This invention belongs to the field of plant growth regulators, specifically relating to a low-residue selective chemical fruit thinning composition for fruit trees and its preparation method. Background Technology

[0002] Fruit thinning is a crucial step in modern fruit tree cultivation and management, directly impacting fruit quality, marketability, and fruit set in the following year. Traditional thinning methods rely primarily on manual labor, resulting in high labor costs and low efficiency, making it difficult to meet the demands of efficient management in large-scale orchards. To improve thinning efficiency, various chemical thinning agents have been developed both domestically and internationally, such as naphthaleneacetic acid (NAA), 6-benzylaminopurine (6-BA), thidiazuron, and ethephon. These agents promote the shedding of weak and inferior fruits by regulating plant hormone levels or inhibiting photosynthesis. However, existing chemical thinning agents generally suffer from the following problems: First, their composition is limited, and their thinning effect is greatly affected by factors such as fruit tree variety, physiological stage, and climate, leading to poor stability. Second, they pose a high risk of residue, especially at high concentrations, which can easily cause phytotoxicity to fruits, leaves, and even flower buds, affecting the following year's yield. Third, the selection of adjuvants is often inappropriate, with some products containing emulsifiers, solubilizers, and other additives that remain on the fruit surface for extended periods and are difficult to degrade.

[0003] Furthermore, existing fruit thinning agents have weak selective fruit thinning capabilities, often resulting in the simultaneous shedding of both high-quality and low-quality fruit, leading to a decrease in the proportion of high-quality fruit and impacting yield and commercial value. Therefore, how to further reduce the risk of pesticide residues and improve the ability to identify and selectively remove low-quality fruit while ensuring effective fruit thinning has become a pressing technical challenge in the field of chemical fruit thinning. To this end, developing a low-toxicity, easily degradable, highly selective fruit thinning composition suitable for various fruit trees has significant practical value and promotional implications. Summary of the Invention

[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a low-residue selective chemical fruit thinning composition and its preparation method. The composition utilizes a compound of 6-benzylaminopurine and ammonium acetate as the active ingredient, supplemented with sodium docusate, methyl oleate (an environmentally friendly adjuvant), L-ascorbic acid derivatives, and polyaspartic acid degradation promoters to synergistically achieve efficient fruit thinning and low residue control. This formulation is suitable for various fruit trees and has the advantages of stable formulation, safety, environmental friendliness, and simple preparation.

[0005] The objective of this invention can be achieved through the following technical solutions: A low-residue selective chemical fruit thinning composition for fruit trees, comprising, by weight percentage: 6%–12% active ingredient, 3%–8% environmentally friendly additives, 1%–3% degradation promoter, and 77%–89% solvent; wherein: The active ingredient is a compound of 6-benzylaminopurine and ammonium acetate; The environmentally friendly additive is a mixture of sodium docusate and methyl oleate; The degradation promoter is one of L-ascorbic acid palmitate, L-ascorbic acid fatty acid ester derivatives, polyaspartic acid, or nano-titanium dioxide with a particle size of 10–50 nm, or any combination thereof. The solvent is a mixture of deionized water and ethanol.

[0006] More preferably, the L-ascorbic acid fatty acid ester derivative in the degradation promoter is selected from one or more of L-ascorbic acid oleate, L-ascorbic acid linoleate, and L-ascorbic acid linolenic acid ester.

[0007] More preferably, the mass ratio of 6-benzylaminopurine to ammonium acetate in the active ingredient is 1:(2.5–4).

[0008] More preferably, the mass ratio of sodium docusate to methyl oleate in the environmentally friendly additive is 1:(1.5–2).

[0009] More preferably, the volume ratio of deionized water to ethanol in the solvent is (3–5):1.

[0010] A method for preparing a low-residue selective chemical fruit thinning composition for fruit trees includes the following steps: S1. Mix deionized water and ethanol in a certain proportion to prepare a solvent; S2. Add L-ascorbate palmitate to the mixed solvent and stir until completely dissolved; S3. Weigh 6-benzylaminopurine and ammonium acetate according to the proportion, add them to the solution obtained in step S2 in sequence, and stir until uniformly dispersed; S4. Mix sodium docusate and methyl oleate in a certain proportion and add them dropwise to the solution obtained in step S3, while stirring continuously; S5. After stirring, filter the mixture using a 200-mesh filter to remove insoluble impurities and obtain the low-residue selective fruit tree chemical thinning composition.

[0011] More preferably, in step S1, the solvent mixing and stirring speed is 150–200 r / min, and the stirring time is 5–8 minutes; in step S2, the stirring time is 10–15 minutes.

[0012] More preferably, in step S3, 6-benzylaminopurine is added first, and after stirring for 15–20 minutes until completely dissolved, ammonium acetate is added and stirring is continued for 10–12 minutes; in step S4, the dropping rate of the environmentally friendly additive is controlled at 1–2 mL / min, and stirring is continued for 20–25 minutes after the dropping is completed.

[0013] More preferably, the entire preparation process is carried out under normal temperature and pressure conditions, and no harmful byproducts are generated.

[0014] More preferably, after filtration in step S5, the obtained composition is dispensed into sealed containers and stored in a cool, dry place at 5–25°C for a period of not less than 12 months.

[0015] The beneficial effects of this invention are: This invention utilizes a specific ratio of 6-benzylaminopurine and ammonium acetate to form an active component, leveraging their synergistic effects in regulating plant cell division and inducing the abscission of weak fruits. This effectively promotes the selective abscission of inferior, peripheral, and weak fruits while preserving central and dominant fruits, thereby increasing the proportion of high-quality fruits and enhancing their marketability. Secondly, the use of sodium docusate and methyl oleate as environmentally friendly adjuvants significantly improves the spreading and absorption rate of the pesticide solution on the fruit surface, while avoiding the pollution risks associated with traditional non-degradable emulsifier residues on the fruit surface. Furthermore, this invention introduces multiple degradation promoters, including L-ascorbic acid palmitate and its fatty acid ester derivatives, polyaspartic acid, and nano-titanium dioxide. These not only accelerate the degradation and metabolism of the active ingredients on the fruit surface and in the environment, reducing pesticide residue risks, but also protect plant tissues from hormonal shocks to a certain extent, improving overall physiological safety. Experiments show that this composition exhibits good versatility and consistent fruit thinning effect on various fruit trees, including apple, pear, and waxberry, with a stable thinning rate of 70%–85% and an increase in high-quality fruit yield of over 30%. No phytotoxicity phenomena such as leaf scorching, leaf drop, or flower bud damage were observed. The formulation can be prepared at room temperature and pressure, requiring no high-temperature, high-pressure, or toxic raw materials. The production process is green and low-consumption, facilitating large-scale promotion. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 The bar chart shows the comparison of fruit thinning rate and high-quality fruit retention rate of the fruit thinning compositions of Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: The low-residue selective fruit tree chemical thinning composition comprises, by weight percentage: 6% active ingredient, 3% environmentally friendly additive, 1% degradation promoter, and 90.0% solvent; The preparation steps are as follows: Weigh 675 mL of deionized water and 225 mL of ethanol, and stir at 180 r / min for 6 minutes to form a homogeneous solvent system. Weigh 10 g of L-ascorbic acid palmitate (1% of the total mass), and slowly add it to the solvent, stirring at room temperature for 12 minutes until completely dissolved. Weigh 1.71 g of 6-benzylaminopurine and 4.29 g of ammonium acetate, first add 6-benzylaminopurine, and stir for 15 minutes until completely dissolved, then add ammonium acetate, and continue stirring for 11 minutes to form a homogeneous solution. Take 0.53 g of sodium docusate and 0.80 g of methyl oleate, mix them evenly, and slowly add them dropwise to the above solution at a rate of 1.5 mL / min. After the addition is complete, continue stirring for 22 minutes. Filter using a 200-mesh stainless steel sieve to remove insoluble impurities, obtaining a clear and homogeneous composition emulsion, which is the low-residue selective fruit thinning chemical composition.

[0020] Example 2: The low-residue selective fruit tree chemical thinning composition comprises, by weight percentage: 12% active ingredient, 8% environmentally friendly additives, 3% degradation promoter, and 77.0% solvent; The preparation steps are as follows: Weigh 641.7 mL of deionized water and 128.3 mL of ethanol, and stir at 180 r / min for 8 minutes to obtain a transparent solution. Take 30 g of nano-titanium dioxide (particle size 10 nm), disperse it in the above solution, and emulsify it for 10 minutes using a high-shear emulsifier (speed 8000 r / min) to obtain a stable dispersed phase. Then weigh 2.40 g of 6-benzylaminopurine and 9.60 g of ammonium acetate, first slowly add 6-benzylaminopurine and stir for 18 minutes until completely dissolved, then add ammonium acetate and stir for 12 minutes to form a transparent solution. Take 2.67 g of sodium docusate and 5.33 g of methyl oleate, mix them evenly, and then add them dropwise to the above solution at a rate of 1.5 mL / min, and continue stirring for 25 minutes after addition. Filter using a 200-mesh sieve to remove impurities, and obtain a milky white homogeneous liquid, which is the low-residue selective fruit thinning chemical composition.

[0021] Example 3: The low-residue selective fruit tree chemical thinning composition comprises, by weight percentage: 9% active ingredient, 5.5% environmentally friendly additives, 2% degradation promoter, and 83.5% solvent; The preparation steps are as follows: 668 mL of deionized water and 167 mL of anhydrous ethanol are stirred at 180 r / min for 6 minutes at room temperature until homogeneous, yielding a clear mixed solvent. 10.00 g each of L-ascorbic acid linoleate and polyaspartic acid are weighed and slowly added to the mixed solvent, maintaining a stirring speed of 200 r / min for 15 minutes to ensure complete dissolution of both components and the formation of a transparent, homogeneous solution. 2.12 g of 6-benzylaminopurine is added to the above solution, and the stirring speed is maintained at 180 r / min for 18 minutes until completely transparent and free of precipitate. Then, 6.89 g of ammonium acetate is added, and stirring continues for 12 minutes to form a stable aqueous phase system. 2.00 g of sodium docusate and 3.50 g of methyl oleate were placed in a beaker and thoroughly premixed to form an oil-phase auxiliary agent system. Using a peristaltic pump with a dropping rate controlled at 1.5 mL / min, the mixed auxiliary agent was slowly added dropwise to the above aqueous phase solution. During the addition, the stirring rate was maintained at 220 r / min. After the addition was completed, stirring was continued for 23 minutes to promote uniform dispersion and interfacial bonding. Impurities were removed by filtration through a 200-mesh sieve, yielding a milky white homogeneous liquid, which is the low-residue selective fruit thinning chemical composition for fruit trees.

[0022] Comparative Example 1: The low-residue selective fruit thinning chemical composition for fruit trees, by mass percentage, consists of the following components: 9% active ingredient, 5.5% environmentally friendly additives, and 85.5% solvent; The preparation steps are as follows: Mix 684 mL of deionized water and 171 mL of anhydrous ethanol, pour the mixture into a clean 1000 mL three-necked flask, install a stirrer, and stir at 180 r / min for 6 minutes at room temperature to form a clear and homogeneous mixed solvent. Weigh 2.12 g of 6-benzylaminopurine and slowly add it to the above mixed solvent, continue stirring for 18 minutes until the solution is clear and free of particles; then add 6.89 g of ammonium acetate and continue stirring for 12 minutes to ensure it is fully dissolved and forms a stable homogeneous system. Take 2.00 g of sodium docusate and 3.50 g of methyl oleate and place them in a clean beaker, mix them evenly, and use a syringe pump to control the dropping rate at 1.5 mL / min to slowly add the auxiliary agent mixture to the active component solution; maintain a stirring rate of 220 r / min during the dropping process, and continue stirring for 23 minutes after the dropping is completed to obtain a homogeneous emulsion. The mixed liquid was filtered through a 200-mesh stainless steel sieve to remove trace amounts of undissolved or aggregated matter. The resulting product was a light yellow, uniform, and fine emulsion-type composition, which is the comparative low-residue selective fruit thinning chemical composition for fruit trees.

[0023] Comparative Example 2: The low-residue selective fruit thinning chemical composition for fruit trees, by mass percentage, consists of the following components: 9% active ingredient, 2% degradation promoter, and 83.5% solvent; The preparation steps are as follows: 712 mL of deionized water and 178 mL of anhydrous ethanol are poured into a clean 1000 mL three-necked flask. A mechanical stirrer is installed, and the stirring speed is set to 180 r / min. The mixture is stirred at room temperature for 6 minutes to obtain a clear and homogeneous mixed solvent. 10.00 g of L-ascorbic acid linoleate and 10.00 g of polyaspartic acid are weighed and slowly added to the above mixed solvent. The stirring speed is maintained at 200 r / min for 15 minutes to ensure that both components are fully dissolved and form a homogeneous and transparent liquid. 2.12 g of 6-benzylaminopurine is added sequentially, and the mixture is stirred for 17 minutes until completely dissolved. Then, 6.89 g of ammonium acetate is added, and the mixture is stirred for another 12 minutes to form a stable and homogeneous system. The mixed solution is then filtered through a 200-mesh stainless steel filter to remove insoluble particles and micro-impurities, which is the comparative low-residue selective fruit thinning chemical composition.

[0024] Performance testing 1. Fruit thinning performance test A field comparative experiment was conducted using robust apple trees of uniform age. The experiment employed a randomized block design, dividing the trees into five treatment groups: Examples 1–3 and Comparative Examples 1–2. Each group consisted of three trees, with three replicates, for a total of 45 trees. The spray composition was diluted to the appropriate concentration (800x for Example 1, 1200x for Example 2, and 1000x for Example 3 and Comparative Examples 1–2). The solution was sprayed evenly 30 days after flowering, when the young fruit diameter was approximately 10–12 mm, avoiding rainy days and extreme high temperatures. Before spraying, the number of young fruits on designated branch groups of each tree was recorded as the initial quantity. Fifteen days after spraying, the number of remaining fruits on each tree was counted, and the thinning rate was calculated. After spraying, the proportion of high-quality fruits located on the central axis of the inflorescence was calculated. After spraying, it was observed whether manual thinning was still necessary. The secondary thinning rate reflected the one-time completion rate of fruit thinning. The results are shown in Table 1 below.

[0025] Table 1 Results of Fruit Thinning Performance Test

[0026] As shown in Table 1, Example 3 exhibits superior performance, demonstrating the best fruit thinning effect, the highest retention rate of high-quality fruit, and the lowest secondary thinning rate. Its fruit thinning rate is 75.3%, the high-quality fruit retention rate is as high as 74.8%, and the secondary thinning rate is only 4.1%, indicating that the composition can effectively remove inferior fruit, retain more high-quality fruit, and complete the fruit thinning task in one step, significantly reducing the need for manual fruit thinning. In contrast, Comparative Examples 1 and 2 performed poorly, with lower fruit thinning rates of 68.5% and 72.3% respectively, lower retention rates of high-quality fruit of 60.2% and 58.6% respectively, and higher secondary thinning rates of 21.4% and 25.9% respectively. This indicates that the lack of degradation promoters or environmentally friendly additives significantly affects the fruit thinning effect and selectivity, increasing the need for manual fruit thinning. Examples 2 and 1, on the other hand, show similarly good results, with fruit thinning rates of 76.5% and 72.5% respectively, higher retention rates of high-quality fruit, and lower secondary thinning rates, indicating that the composition of the present invention has good overall performance in terms of fruit thinning effect and selectivity.

[0027] 2. Pesticide residue testing Fruit samples were randomly collected from each experimental fruit tree at different time points after spraying (1 day, 7 days, 14 days, and 30 days after spraying). Fruits at different heights and locations were selected at each sampling point to ensure representativeness. The collected fruit samples were washed, peeled, and cut, and analyzed using high-performance liquid chromatography (HPLC) to detect the main active ingredient (6-benzylaminopurine) and its residue levels in the fruit thinning agent. The concentration of the active ingredient in the samples was quantitatively analyzed using a standard curve method. Three replicate samples were collected at each time point, and the average value was taken. The results are shown in Table 2 below.

[0028] Table 2 Pesticide Residue Levels

[0029] As shown in Table 2, the residue levels of Example 3 at each time point were significantly lower than those of Comparative Examples 1 and 2, and the residue level was below the detection limit 30 days after spraying, demonstrating the excellent degradation performance of the composition. In particular, the residue levels of Example 3 at 1 day and 7 days after spraying were only 0.03 mg / kg and 0.01 mg / kg, respectively, far lower than the 0.10 mg / kg and 0.06 mg / kg of Comparative Example 1, indicating that the composition with the added degradation promoter has a faster degradation rate and reduces the impact of pesticide residues on the fruit. The residue levels of Examples 1 and 2 also showed good performance, with residue levels below 0.01 mg / kg 30 days after spraying. In contrast, the residue level of Comparative Example 1 was higher, especially at 1 day after spraying, highlighting the importance of the lack of a degradation promoter in reducing pesticide residues.

[0030] 3. Fruit tree yield and quality testing After spraying, the total yield (unit: kg) of each fruit tree was recorded, and fruit quality was evaluated based on indicators such as fruit size, appearance (color, shape, etc.), sugar content, and acidity. The yield of each fruit tree was measured by counting the total weight of the fruit at harvest. High-quality fruit was defined as fruit with perfect appearance, moderate size (single fruit weight 150-200g, fruit diameter 70-80mm), free from pests and diseases, and free from pesticide damage spots. Priority was given to fruits retained from the central axis of the inflorescence during the initial fruit thinning. The results were collected manually, and the proportion of high-quality fruit in the total fruit was calculated. Sugar content and acidity were measured using a saccharimeter and a pH meter, respectively. Ten high-quality fruits were randomly selected from each experimental group, and their sugar and acidity were measured. The average value was taken as the final data for that group. All tests were conducted 75 days after spraying, and the results are shown in Table 3 below.

[0031] Table 3 Results of Fruit Tree Yield and Quality

[0032] As shown in Table 3, the fruit yield and fruit quality of Examples 1–3 were superior to those of Comparative Examples 1 and 2. Example 3 showed the most outstanding performance, with a yield of 12.8 kg per tree, a high-quality fruit ratio of 80.0%, a sugar content of 15.0 °Brix, and an acidity controlled at 0.58%, achieving both high yield and high quality. In contrast, Comparative Example 1, lacking degradation promoters, had the lowest yield, a high-quality fruit ratio of only 68.5%, lower sugar content, and higher acidity, indicating a significant deficiency in improving fruit marketability. Comparative Example 2, lacking environmentally friendly additives, although having a slightly higher total yield than Comparative Example 1, still had a lower high-quality fruit ratio and lower sugar content, and its fruit appearance quality was also affected.

[0033] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] The foregoing has shown and described 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 embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A low-residue selective chemical fruit thinning composition for fruit trees, characterized in that, By weight percentage, it consists of the following components: 6%–12% active ingredient, 3%–8% environmentally friendly additives, 1%–3% degradation promoters, and 77%–89% solvent; wherein: The active ingredient is a compound of 6-benzylaminopurine and ammonium acetate; The environmentally friendly additive is a mixture of sodium docusate and methyl oleate; The degradation promoter is one of L-ascorbic acid palmitate, L-ascorbic acid fatty acid ester derivatives, polyaspartic acid, or nano-titanium dioxide with a particle size of 10–50 nm, or any combination thereof. The solvent is a mixture of deionized water and ethanol.

2. The low-residue selective fruit thinning chemical composition according to claim 1, characterized in that, The L-ascorbic acid fatty acid ester derivative in the degradation promoter is selected from one or more of L-ascorbic acid oleate, L-ascorbic acid linoleate, and L-ascorbic acid linolenic acid ester.

3. The low-residue selective fruit thinning chemical composition according to claim 1, characterized in that, The mass ratio of 6-benzylaminopurine to ammonium acetate in the active ingredient is 1:(2.5–4).

4. The low-residue selective fruit thinning chemical composition according to claim 1, characterized in that, The mass ratio of sodium docusate to methyl oleate in the environmentally friendly additive is 1:(1.5–2).

5. The low-residue selective fruit thinning chemical composition according to claim 1, characterized in that, The volume ratio of deionized water to ethanol in the solvent is (3–5):

1.

6. A method for preparing a low-residue selective chemical fruit thinning composition as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Mix deionized water and ethanol in a certain proportion to prepare a solvent; S2. Add L-ascorbate palmitate to the mixed solvent and stir until completely dissolved; S3. Weigh 6-benzylaminopurine and ammonium acetate according to the proportion, add them to the solution obtained in step S2 in sequence, and stir until uniformly dispersed; S4. Mix sodium docusate and methyl oleate in a certain proportion and add them dropwise to the solution obtained in step S3, while stirring continuously; S5. After stirring, filter the mixture using a 200-mesh filter to remove insoluble impurities and obtain the low-residue selective fruit tree chemical thinning composition.

7. The preparation method according to claim 6, characterized in that, In step S1, the solvent mixing and stirring speed is 150–200 r / min, and the stirring time is 5–8 minutes; in step S2, the stirring time is 10–15 minutes.

8. The preparation method according to claim 6, characterized in that, In step S3, 6-benzylaminopurine is added first, and the mixture is stirred for 15–20 minutes until completely dissolved. Then, ammonium acetate is added and stirring is continued for 10–12 minutes. In step S4, the dropping rate of the environmentally friendly additive is controlled at 1–2 mL / min, and stirring is continued for 20–25 minutes after the addition is completed.

9. The preparation method according to claim 6, characterized in that, The entire preparation process is carried out under normal temperature and pressure conditions, and no harmful byproducts are generated.

10. The preparation method according to claim 6, characterized in that, After filtration in step S5, the obtained composition is dispensed into sealed containers and stored in a cool, dry place at 5–25°C for a period of not less than 12 months.

Images