A plant-derived herbicide and its preparation method

Abstract

This invention discloses a plant-derived herbicide and its preparation method, specifically relating to the field of biological weed control. The whole plant of *Coriandrum sativum* is dried, pulverized, and sieved. After ultrasonic extraction with an organic solvent, the extract is concentrated to obtain a paste-like extract. This plant-derived herbicide contains the following raw materials in volume fractions: 10 parts *Coriandrum sativum* extract, 2 parts emulsifier, and 88 parts water. The technical solution of this invention solves the problem of environmental pollution and pesticide residues exacerbated by existing chemical herbicides. Furthermore, the plant-derived herbicide of this invention, after being prepared into a stable formulation, can effectively control annual weeds, achieving a control effect of over 75% on weeds in farmland. The application of this plant-derived herbicide can significantly reduce the amount of chemical herbicides used, thus reducing environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of biological control of weeds, and in particular to a plant-derived herbicide and its preparation method. Background Technology

[0002] In agricultural production, weed control has always been a crucial link in ensuring healthy crop growth and improving crop yield and quality. For a long time, chemical control has been the primary means of weed control in farmland due to its significant advantages such as high efficiency and convenience, occupying a dominant position in agricultural production. While the large-scale and long-term use of chemical herbicides has effectively controlled the growth and spread of weeds to a certain extent, a series of negative effects have become increasingly prominent.

[0003] First, environmental pollution is a serious concern. Residues of chemical herbicides in soil and water not only disrupt the ecological balance of the soil, affecting the normal activity of soil microorganisms and soil fertility, but can also enter water bodies through rainwater runoff and infiltration, causing severe damage to aquatic ecosystems and threatening the survival and reproduction of aquatic organisms. Second, pesticide residues in agricultural products directly impact human food safety and health. Long-term ingestion of chemical herbicide residues in agricultural products may cause chronic toxicity in humans, leading to various diseases such as cancer and neurological disorders, posing potential health risks to consumers. Third, the rise of herbicide resistance in weeds has become a major challenge in chemical control. With the frequent use of chemical herbicides, weeds are gradually developing resistance through natural selection, leading to a significant decrease in herbicide effectiveness. Farmers are forced to increase the dosage of herbicides or switch to different types, which not only further exacerbates environmental pollution and pesticide residue problems but also increases agricultural production costs.

[0004] Given the numerous drawbacks of chemical herbicides, finding safer, more environmentally friendly, and sustainable weed control methods has become an urgent need in the field of agricultural research. Against this backdrop, plant-derived herbicides have emerged. Plant-derived herbicides are developed based on natural biological compounds, metabolites, or plant materials, and possess many unique advantages. Their targets are novel; unlike traditional chemical herbicides, they act on specific physiological and biochemical processes of weeds, thus achieving effective weed control. They are highly selective, exhibiting high control efficacy against target weeds while having minimal impact on surrounding crops and beneficial organisms. They are less prone to resistance development; due to the complex composition of plant-derived herbicides, weeds are unlikely to develop resistance in a short period, allowing for long-term stable use. They degrade rapidly in the environment, quickly decomposing in the natural environment and reducing long-term environmental pollution. They are safe for the environment and livestock, reducing the risk of pesticide residues in agricultural products and ensuring human food safety and health. Furthermore, compared to the development of traditional chemical herbicides, the approach of developing novel plant-derived herbicides using natural products has significant advantages such as lower R&D costs, stronger research focus, and shorter development time. Therefore, the research and development of plant-derived herbicides not only meets the requirements of sustainable development in modern agriculture, but also has broad market prospects and application value, and is expected to become an important development direction in the field of weed control in the future. Summary of the Invention

[0005] The present invention aims to provide a plant-derived herbicide and its preparation method, which solves the problem that existing chemical herbicides exacerbate environmental pollution and pesticide residues.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a plant-derived herbicide, wherein the active ingredient of the plant-derived herbicide is a coriander extract.

[0007] Technical principle and effect: This plant-derived herbicide can significantly inhibit the germination and emergence of annual weeds.

[0008] Furthermore, the preparation method of the Coriander extract is as follows: S1. The whole plant of Coriander is dried, pulverized, and sieved. S2. The powder from step S1 is extracted by ultrasonic extraction using an organic solvent; S3. The liquid from step S2 is concentrated under reduced pressure to obtain a paste-like concentrate.

[0009] Furthermore, the *Coriander* extract is an alcohol, ester, or ketone extract of the whole *Coriander* herb, including one or more of methanol, ethanol, n-butanol, ethyl acetate, and acetone.

[0010] Furthermore, the herbicide comprises the following raw materials in volume fractions: 10 parts of Coriander extract, 2 parts of emulsifier, and 88 parts of water.

[0011] Furthermore, the emulsifier is Tween 80.

[0012] Another technical solution provided by the present invention: a method for preparing a plant-derived herbicide, characterized by comprising the following steps: A1. Mix the above-mentioned Coriander extract with the emulsifier and use a high-speed shearing machine to fully emulsify the Coriander extract. A2. Mix water with the raw materials from step A1, and emulsify using a high-speed shearing machine until the water-emulsion is stable and does not separate into layers upon standing, thus obtaining a plant-derived herbicide formulation.

[0013] Furthermore, the mixing time in step A1 is 10 minutes.

[0014] Furthermore, in steps A1 and A2, the shearing speed of the high-speed shearing machine is 4000 rpm, and the shearing time is 10 min.

[0015] Another technical solution provided by the present invention is the application of a plant-derived herbicide, which involves applying the herbicide of claims 1-8 to the control of annual weeds in farmland.

[0016] Furthermore, the plant-derived herbicide is applied before weeds emerge, and is applied via soil spraying.

[0017] Compared with existing technologies, the beneficial effects of this solution are: 1. The extract of Coriander in this solution is isolated from natural plant materials, so there are few ecological or environmental risks after it is applied to nature, making it a safe biological control product.

[0018] 2. The plant-derived herbicide based on the extract of Coriander can effectively control a variety of annual weeds, has a broad spectrum of weed control, and has the potential to be further developed into a biological herbicide.

[0019] 3. The method for preparing plant-derived herbicides in this scheme is simple to operate and easy to scale up for production; moreover, the prepared plant-derived herbicides are stable and easy to store for a long time. Attached Figure Description

[0020] Figure 1 The image shows the inhibitory effect of Coriander extract on the germination of Portulaca oleracea. Figure 2 The graph shows the inhibitory effect of Coriander extract on barnyardgrass germination. Figure 3 This is a diagram showing the safety test results of plant-derived herbicides on tobacco. Figure 4 This diagram illustrates the weed control effect of plant-derived herbicides. Detailed Implementation

[0021] The present invention will be further described in detail below through specific embodiments: Example 1

[0022] Preparation of Coriander Extract: The whole herb of *Coriandrum sativum* was dried in a drying oven at 40℃~50℃, pulverized, and sieved with a sieve aperture of 0.4mm. The dried plant material powder was added to an organic solvent at a ratio of 1:10 (w / v) and extracted at room temperature for 24 h. Then, it was ultrasonically extracted for 30 min in an ultrasonic cleaner (40℃, 100Hz). The filtered residue was extracted twice more using the above process. The filtrates from the three extractions were combined and concentrated by vacuum distillation at 45℃ to obtain *Coriandrum sativum* extract. The *Coriandrum sativum* extract was prepared into a stock solution of 1 g·DW / mL using methanol.

[0023] In this embodiment, the organic solvent used to prepare the coriander extract is an alcohol, ketone, or ester, including one or more of methanol, ethanol, propanol, butanol, n-butanol, acetone, and ethyl acetate. Example 2

[0024] Determination of the inhibitory activity of Coriander extract on weed germination: The extract of Coriander from Example 1 was prepared into solutions of 100 mg / mL, 50 mg / mL, 25 mg / mL, 12.5 mg / mL and 6.25 mg / mL for later use.

[0025] The inhibitory effect of *Pheretima aspergillum* extract on weed germination was determined using a seed germination method. Purslane and barnyardgrass seeds were soaked in water for 2 hours. Two layers of filter paper were placed in 90 mm diameter petri dishes, and 5 mL of different concentrations of prepared *Pheretima aspergillum* extract solutions were added to each dish. A 960 g / L metolachlor solution (100 mL / mu, equivalent to 3.2 mg / mL of active ingredient) was used as a herbicide control, while an equal volume of sterile water was added to the blank control group. The fully soaked weed seeds were placed on filter paper, with 30 seeds evenly placed in each petri dish. The dishes were sealed with perforated plastic wrap and placed in an AI climate chamber at 28℃ and 85% relative humidity for 3 days. After 3 days, the number of germinating seeds, root length, and shoot length were recorded (see Table 1 below). Figure 1 The seed germination inhibition rate, root length inhibition rate, and stem length inhibition rate were calculated.

[0026] In this embodiment, the extract of *Coriandrum sativum* showed a strong inhibitory effect on the germination and growth of *Portulaca oleracea* seeds. With increasing extract concentration, the inhibition rates of seed germination, root length, and shoot length all increased. At concentrations of 6.25–100 mg / mL, the inhibition rate of seed germination was higher than that of the herbicide control; at concentrations of 12.5–100 mg / mL, the inhibition rate of root length was higher than that of the herbicide control; and at concentrations of 25–100 mg / mL, the inhibition rate of shoot length was higher than that of the herbicide control.

[0027] Table 1. Germination inhibition rate of Coriander extract solution on Portulaca oleracea In this embodiment, the extract of *Coriandrum sativum* showed a strong inhibitory effect on the germination and growth of barnyard grass seeds. With increasing extract concentration, the inhibition rates of germination, root length, and shoot length all increased (as shown in Table 2 below). At concentrations of 6.25–100 mg / mL, the inhibition rate of barnyard grass seed germination was higher than that of the herbicide control; at concentrations of 50–100 mg / mL, the inhibition rates of root and shoot length were also higher than those of the herbicide control.

[0028] Table 2. Germination inhibition rate of Coriander extract on barnyardgrass Example 3

[0029] Preparation of plant-derived herbicides: The *Pyrrosia lingua* extract from Example 1 was mixed with the emulsifier Tween 80 in a specified ratio for 10 minutes. The weight fractions of the *Pyrrosia lingua* extract and the emulsifier Tween 80 were 10 parts and 2 parts, respectively. The mixture was thoroughly emulsified using a high-speed shear mill for 10 minutes. 88 parts of water were then mixed with the raw materials from the above steps and emulsified using a high-speed shear mill at 4000 rpm for 10 minutes until the water-in-oil emulsion was stable and did not separate upon standing, thus obtaining the plant-derived herbicide formulation. Example 4

[0030] Safety testing of plant-derived herbicides on tobacco: The plant-derived herbicide of Example 3 was prepared into solutions of 100 mg / mL, 50 mg / mL, 25 mg / mL, 12.5 mg / mL and 6.25 mg / mL for later use.

[0031] Fill 25cm diameter plastic pots with nutrient soil mixed with tobacco seedling substrate (substrate:soil mass ratio = 1:2). Use an automatic sprayer to evenly spray the prepared plant-derived herbicide gradient solution onto the soil surface. Seven days after treatment, transplant tobacco seedlings with 3-4 leaves and uniform growth, one seedling per pot. A blank control and a herbicide treatment control were also established. Each treatment was replicated four times. The transplanted seedlings were placed in a 28℃ greenhouse for cultivation. Seedling growth was observed regularly, and leaf length, leaf width, and plant height were measured 30 days after application (see Table 3 below). Figure 3 (As shown), to evaluate the safety of Coriander extract for tobacco.

[0032] Table 3. Effects of plant-derived herbicides on tobacco growth It can be seen that at doses of 6.25–100 mg / mL, there were no significant differences in leaf length, leaf width, and plant height between the plant-derived herbicide formulation treatment group and the blank control group, indicating good safety for tobacco. Example 5

[0033] Herbicidal activity assay of plant-derived herbicides against field weeds: The plant-derived herbicide formulation from Example 3 was prepared into a 50 mg / mL solution and sprayed onto the soil at a water volume of 30 L / mu. Weed emergence was assessed at 7, 14, and 21 days after application, and the plant control efficacy was calculated. The fresh weight of the above-ground portion of the weeds was assessed 21 days after treatment, and the fresh weight control efficacy was calculated. The results showed (as shown in Table 4 and...) Figure 4 As shown in the figure): after treatment with the solution of the plant-derived herbicide formulation, the plant control efficacy against annual weeds was 81.35%, 78.46%, and 75.56% at 7 days, 14 days, and 21 days, respectively, and the fresh weight control efficacy was 84.08% at 21 days, showing good potential for further development into a plant-derived herbicide.

[0034] Table 4. Field control efficacy of MA4 against weeds The above are merely embodiments of the present invention, and common knowledge such as specific structures and / or characteristics in the solutions are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A plant-derived herbicide, characterized in that: The active ingredient in the plant-derived herbicide is coriander extract.

2. The plant-derived herbicide according to claim 1, characterized in that: The preparation method of the Coriander extract is as follows: S1. The whole plant of Coriander is dried, pulverized, and sieved. S2. The powder from step S1 is extracted by ultrasonic extraction using an organic solvent; S3. The liquid from step S2 is concentrated under reduced pressure to obtain a paste-like concentrate.

3. The plant-derived herbicide according to claim 1, characterized in that: The *Coriander* extract is an alcohol, ester, or ketone extract of the whole *Coriander* herb, including one or more of methanol, ethanol, n-butanol, ethyl acetate, and acetone.

4. A plant-derived herbicide according to claim 1, characterized in that: The herbicide comprises the following raw materials in volume fractions: 10 parts of Coriander extract, 2 parts of emulsifier, and 88 parts of water.

5. A plant-derived herbicide according to claim 4, characterized in that: The emulsifier is Tween 80.

6. A method for preparing a plant-derived herbicide, characterized in that: Includes the following steps: A1. The Coriander extract of claim 4 is stirred and mixed with an emulsifier, and the Coriander extract is fully emulsified by using a high-speed shearing machine. A2. Mix water with the raw materials from step A1, and emulsify using a high-speed shearing machine until the water-emulsion is stable and does not separate into layers upon standing, thus obtaining a plant-derived herbicide formulation.

7. The method for preparing a plant-derived herbicide according to claim 6, characterized in that: The mixing time in step A1 is 10 minutes.

8. The method for preparing a plant-derived herbicide according to claim 6, characterized in that: In steps A1 and A2, the high-speed shearing machine has a shearing speed of 4000 rpm and a shearing time of 10 min.

9. The application of a plant-derived herbicide, characterized in that: The herbicides of claims 1-8 are applied to the control of annual weeds in farmland.

10. The application of a plant-derived herbicide according to claim 9, characterized in that: The plant-derived herbicide is applied before weeds emerge and is applied via soil spraying.

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