Biological herbicide based on schizonepeta leaf water extract and preparation method and application thereof

Abstract

This invention relates to the field of herbicide technology, specifically to a biological herbicide based on an aqueous extract of Nepeta cataria leaves, its preparation method, and its application. For the first time, this invention discloses and confirms, through systematic bioassays, that the aqueous extract of Nepeta cataria leaves has a significant and concentration-dependent allelopathic inhibitory effect on the seed germination and seedling growth of barnyard grass, a major weed in farmland. This extract simultaneously and significantly inhibits barnyard grass's germination potential (germination rate), germination rate (germination capacity), root length, and shoot length (early establishment), achieving synergistic blocking of multiple key stages in the early life cycle of the weed, resulting in a more thorough control effect. This invention clarifies the key concentration range (0.033 g / mL – 0.1 g / mL) and the optimal concentration (0.1 g / mL) for the significant inhibitory effect of the aqueous extract of Nepeta cataria leaves, providing a precise formulation basis for product development.

Description

Technical Field

[0001] This invention relates to the field of herbicide technology, specifically to a biological herbicide based on aqueous extract of catnip leaves, its preparation method, and its application. Background Technology

[0002] barnyard grass ( Echinochloa crus-galli Herbicides are a globally prevalent and harmful weed in farmland, competing with crops for water, nutrients, light, and heat, severely impacting crop yields. The long-term use of chemical herbicides has led to increasingly serious problems such as herbicide resistance, environmental pollution, and residues in agricultural products. Therefore, developing efficient, safe, and environmentally friendly new bio-based herbicides has become an important direction for sustainable agricultural development.

[0003] Allelopathic effects refer to the phenomenon where plants influence the growth and development of neighboring plants by releasing secondary metabolites. Allelochemicals used as herbicides often focus on extracting natural allelochemicals from plants or microorganisms, which aligns with environmental protection requirements and reduces the pollution problems associated with chemical herbicides. Patent CN118542321A discloses the application of a herbicide and genistein or palmitic acid in suppressing weed growth. This patent uses genistein or palmitic acid extracted and isolated from alfalfa as the active ingredient in the herbicide, and the two can be used alone or in combination. Patent CN102617530A discloses a compound extracted from Italian cocklebur and its application as a herbicide. The core of this patent is the extraction and purification of cocklebur saponin (a sesquiterpene lactone) from Italian cocklebur fruit. The extraction process involves ethanol extraction, defatting, and two column chromatography steps to obtain a substance with a purity of over 95%. This allelochemical, when diluted and sprayed, can significantly inhibit the growth of both monocotyledonous and dicotyledonous plants even at low concentrations. It also decomposes easily in nature, causing no residual pollution. Patent CN108684246A discloses a method for inhibiting the germination of jointed goatgrass seeds using plant allelopathic effects. This patent utilizes at least one of the following: fresh leaves of camphor, neem, sumac, cedar, and neem pulp. An aqueous extract (preferably 25-100 mg / L) is prepared by ultrasonic vibration. The 100 mg / L camphor leaf extract shows a significant inhibitory effect, reducing the germination rate of jointed goatgrass seeds to only 13.33%. It can be used for the biological control of jointed goatgrass through spraying, root irrigation, and other methods.

[0004] Catnip ( Schizonepeta tenuifolia As a common medicinal plant, its volatile components and water-soluble substances may have the potential to suppress weeds. However, there are no reports in the current technology regarding the use of catnip leaf extract as a biological herbicide. Summary of the Invention

[0005] To address the aforementioned shortcomings in the prior art, the present invention aims to provide a biological herbicide based on aqueous extract of catnip leaves, its preparation method, and its application.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: On the one hand, a biological herbicide based on catnip leaf aqueous extract is provided, which uses catnip leaf aqueous extract as the sole active ingredient.

[0007] Furthermore, the preparation method of the aqueous extract of catnip leaves includes the following steps: Take fresh catnip leaves, wash and crush them, add deionized water, extract at 25-30°C, filter, centrifuge and concentrate.

[0008] Further, the leaves of the catnip were crushed into 1-2 mm particles and then extracted.

[0009] Further, add deionized water at a material-to-liquid ratio of 1:10 and extract at 25-30°C for 24 hours.

[0010] Furthermore, the centrifugation speed was 4000 rpm for 15 minutes, concentrating the volume to 1 / 5 of the original volume.

[0011] On the other hand, it provides the application of biological herbicides based on catnip leaf aqueous extract in weed control.

[0012] Furthermore, a 0.033 g / mL aqueous extract of catnip leaves was used for preventative application, a 0.05 g / mL aqueous extract of catnip leaves was used for routine weed control, and a 0.1 g / mL aqueous extract of catnip leaves was used for thorough weed eradication.

[0013] The beneficial effects of this invention are as follows: This invention, through systematic bioassays, is the first to systematically evaluate the allelopathic effects of catnip leaf aqueous extract on weed seed germination and seedling growth, aiming to explore its application value as a lead material for biological herbicides. Detailed Implementation

[0014] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0015] Example I. Materials and Methods 1. Preparation of aqueous extract of catnip leaves Mother liquor: Weigh 20 g of dry catnip leaves at a ratio of 1:10 (w / v), add 200 ml of distilled water, extract at room temperature for 24 h, and then filter to obtain a mother liquor with a concentration of 0.1 g / mL.

[0016] The specific preparation method includes the following steps: (1) Raw material pretreatment: Select fresh catnip leaves and wash with deionized water; (2) Pulverization: mechanically pulverize to 1-2 mm particles; (3) Water extraction: add deionized water at a material-to-liquid ratio of 1:10 and extract at 25-30°C for 24 hours; (4) Separation and purification: filter, centrifuge, and concentrate; centrifuge at 4000 rpm for 15 minutes and concentrate to 1 / 5 of the original volume; (5) Sterilization and packaging: filter with a 0.22 μm filter membrane and aseptically package.

[0017] Dilution: The mother liquor was diluted sequentially with distilled water to obtain three gradient concentrations of 0.05 g / mL, 0.033 g / mL, and 0.025 g / mL, with distilled water as the control (CK).

[0018] 2. Bioassay Test plant: barnyard grass seeds.

[0019] Germination experiments were conducted using the standard petri dish and filter paper method. Specifically, filter paper was placed in sterile petri dishes, and 5 mL of a specific concentration of Nepeta cataria leaf extract was added. Thirty surface-sterilized recipient plant seeds were evenly placed in each dish and cultured at 25°C under 12h / 12h light / dark conditions. Distilled water treatment served as a blank control. Germination was observed and recorded regularly, and seedling root length, shoot length, and other growth indicators were measured on day 7.

[0020] Germination test: Each concentration was replicated 3 times, with 30 seeds per replicate. The number of germinated seeds was recorded daily, and the germination rate (final number of germinated seeds / total number of seeds × 100%) and germination potential (number of germinated seeds on day 4 / total number of seeds × 100%) were calculated.

[0021] Seedling growth measurement: After the culture was completed, 10 seedlings were randomly selected from each replicate and their root length and shoot length were measured.

[0022] 1. The allelopathic effect intensity of each individual indicator (such as seed germination rate, root length, etc.) is quantified by the allelopathic effect index (RI).

[0023] The RI value is calculated using the following formula: RI = 1 – T / C (when the treatment value T ≥ the control value C) RI = T / C – 1 (when the treatment value T < the control value C) In the formula: T: represents the measured value after treatment with the aqueous extract of catnip leaves (such as the germination rate, average root length, etc. of the treatment group); C: represents the corresponding measured value of the blank control group.

[0024] Biological significance of RI value: RI>0: This indicates that the extract has a promoting effect on the measured index.

[0025] RI = 0: indicates no effect.

[0026] RI<0: indicates that the indicator has an inhibitory effect.

[0027] The absolute value of RI directly reflects the strength of the promoting or inhibiting effect.

[0028] 2. Calculation of the Synthetic Effect (SE) To comprehensively evaluate the overall effect of a treatment on recipient plants, this invention further calculates its comprehensive allelopathic effect index (SE). The SE value is the arithmetic mean of the RI values ​​of all measured indicators under that treatment, and the calculation formula is as follows: SE = (RI1 + RI2 + ... + RI) n ) / n In a specific implementation of the present invention: Typically, four key indicators are measured: seed germination rate (GP), germination potential (GE), seedling root length (RL), and seedling shoot length (SL). Therefore, the formula for calculating the comprehensive allelopathic effect index (SE) is as follows: SE = [RI(GP) + RI(GE) + RI(RL) + RI(SL)] / 4 3. Suppression Intensity Level Classification Standards For ease of understanding and comparison, this invention classifies and defines the intensity of allelopathic inhibition based on the absolute value (|SE|) ​​of the comprehensive allelopathic effect index: |SE| ≥ 0.5: defined as "extremely strong suppression"; 0.3 ≤ |SE| < 0.5: defined as "strong suppression"; 0.1 ≤ |SE| < 0.3: defined as "moderate inhibition"; |SE|<0.1: Defined as “weak inhibition”.

[0029] II. Results and Analysis 1. Inhibitory effect on seed germination Germination rate: The average germination rate of the control group was 45.67%. As the concentration of the extract increased, the germination rate continued to decrease. At a concentration of 0.1 g / mL, the germination rate was inhibited to 15.67%, with an inhibition rate of 65.69%.

[0030] Germination potential: The average germination potential of the control group was 41.0%. The germination potential of the treatment group was more significantly inhibited. At a concentration of 0.1 g / mL, the germination potential was only 9.0%, with an inhibition rate as high as 78.05%, indicating that the extract significantly delayed and inhibited the initial germination process of barnyard grass.

[0031] Table 1: Trends in Germination Indicators The above data indicate that the aqueous extract of catnip leaves has a significant concentration-dependent inhibitory effect on barnyard grass seed germination.

[0032] 2. Inhibitory effect on seedling growth Root length: The average root length of the control group was 3.03 mm. At a concentration of 0.1 g / mL, the root length was drastically inhibited to 0.23 mm, with an astonishing inhibition rate of 92.31%, indicating that the extract severely damaged the root development of barnyard grass.

[0033] Bud length: The average bud length in the control group was 8.33 mm. At a concentration of 0.1 g / mL, the bud length was inhibited to 2.07 mm, with an inhibition rate of 75.2%.

[0034] Table 2: Trends in Growth Indicators The above data show that the extract strongly inhibits the growth of both roots and shoots of barnyard grass seedlings, and the inhibitory effect on roots is stronger than that on aboveground parts.

[0035] 3. Allelopathic Index (RI) and the "low-promotion, high-inhibition" phenomenon Analysis of the RI values ​​revealed that at a low concentration of 0.025 g / mL, the RI values ​​for root length and shoot length were -0.011 and -0.092, respectively, indicating a weak promoting effect, exhibiting the typical allelopathic effect of "promotion at low concentrations and inhibition at high concentrations." When the concentration was ≥ 0.033 g / mL, the RI values ​​for all indicators were negative, indicating an inhibitory effect, and the inhibitory intensity increased sharply with increasing concentration.

[0036] The observed "low-promoting, high-inhibiting" hormesis effect suggests that its mechanism of action may be related to endogenous hormone regulation or metabolic pathway interference, which is different from the single killing mechanism of traditional herbicides and may not easily induce weed resistance.

[0037] Table 3: Analysis of Allelopathic Index (RI) 4. Key active concentration and effect evaluation The most effective concentration: 0.1 g / mL showed the strongest overall inhibitory effect on germination and growth, with an average inhibition rate of 77.81%.

[0038] Key inflection point: At a concentration of 0.033 g / mL, the inhibition rate of germination rate and germination potential both exceeded 60%, marking the transition of the inhibition effect from mild to significant.

[0039] Sensitivity ranking: The sensitivity of each indicator to the extract is as follows: germination potential > germination rate > root length > shoot length. This indicates that the primary target of the catnip extract is to interfere with the germination process of barnyard grass seeds.

[0040] Table 4: Comparison of Inhibition Rates of Various Indicators Table 5: Comparison of Prevention and Control Strategies In summary, this invention, for the first time through systematic bioassays, discloses and confirms that the aqueous extract of Nepeta cataria leaves has a significant and concentration-dependent allelopathic inhibitory effect on seed germination and seedling growth of barnyard grass, a major weed in farmland. This extract simultaneously and significantly inhibits barnyard grass germination potential (germination rate), germination rate (germination capacity), root length, and shoot length (early establishment), achieving synergistic blocking of multiple key stages in the early life cycle of the weed, resulting in a more thorough control effect. This invention clarifies the key concentration range (0.033 g / mL - 0.1 g / mL) and the optimal concentration (0.1 g / mL) for the aqueous extract of Nepeta cataria leaves to produce a significant inhibitory effect, providing a precise formulation basis for product development.

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0042] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A biological herbicide for controlling barnyard grass based on an aqueous extract of catnip leaves, characterized in that, A 0.033 g / mL aqueous extract of catnip leaves is used for preventative application, a 0.05 g / mL aqueous extract of catnip leaves is used for routine weed control, and a 0.1 g / mL aqueous extract of catnip leaves is used for thorough weed eradication.

2. The method for preparing the biological herbicide for controlling barnyard grass based on the aqueous extract of Nepeta cataria leaves according to claim 1, characterized in that, Includes the following steps: Take fresh catnip leaves, wash and crush them, add deionized water, extract at 25-30°C, filter, centrifuge and concentrate.

3. The method for preparing a biological herbicide for controlling barnyard grass based on aqueous extract of catnip leaves according to claim 2, characterized in that, The leaves of catnip are crushed into 1-2 mm particles and then extracted.

4. The method for preparing a biological herbicide for controlling barnyard grass based on aqueous extract of catnip leaves according to claim 2, characterized in that, Add deionized water at a material-to-liquid ratio of 1:10 and extract at 25-30°C for 24 hours.

5. The method for preparing a biological herbicide for controlling barnyard grass based on aqueous extract of catnip leaves according to claim 2, characterized in that, Centrifuge at 4000 rpm for 15 minutes to concentrate to 1 / 5 of the original volume.

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