Growth inhibition preparation and method for mikania micrantha

Abstract

The invention relates to the technical field of biological prevention and control of invasive plants, in particular to a preparation and method for inhibiting growth of mikania micrantha, and the method comprises the following steps: obtaining freeze-dried powder of a callicarpa nudiflora leaf extract; preparing a water-soluble reagent of freeze-dried powder of the callicarpa nudiflora leaf extract; the water-soluble reagent is sprayed and applied to mikania micrantha plants. The callicarpa nudiflora leaf extract freeze-dried powder is relatively simple in preparation process, relatively low in cost, easy to store, capable of effectively inhibiting growth of mikania micrantha, free of the problem of drug resistance like chemical agents, environmentally friendly, free of damage to soil and ecological systems and capable of meeting the requirement of sustainable development; the callicarpa nudiflora leaf extract reagent is sprayed in January to February and April to May every year, staged precise prevention and control of the seed germination stage and the stem node adventitious root growth stage of the mikania micrantha can be achieved, and the reproduction rate of the mikania micrantha is reduced more efficiently.

Description

Technical Field

[0001] The present invention relates to the technical field of biological control of invasive plants, and in particular to a preparation and method for inhibiting the growth of microchamomile. Background Art

[0002] Mikania micrantha, also known as microchamomile, is a herbaceous vine in the genus Mikania in the Asteraceae family. Native to Central and South America, it is now widely distributed in tropical and subtropical regions of Asia and Oceania. It is a highly harmful weed. Mikania micrantha has spread to many parts of my country, particularly in southern China. Its eradication is extremely difficult, making it a highly harmful invasive alien species. In 2001, the World Conservation Union (IUCN) listed it as one of the world's 100 most harmful invasive alien species. Due to its rapid spread, it was listed among my country's first 16 harmful alien species. It is now one of the most serious invasive plants in South my country, and effective control of it has always been a global challenge. With its strong asexual reproduction ability (rapid rooting of stem nodes) and efficient resource competition strategies (such as shading and allelochemical release), Mikania micrantha can quickly form a single dominant community, leading to a sharp decline in local biodiversity and an imbalance in soil nutrients. Currently, the prevention and control of microchamomile mainly relies on chemical herbicides and manual removal. However, the long-term application of herbicides such as glyphosate can easily lead to problems such as increased resistance, soil pollution, and accidental damage to non-target organisms. Manual removal, on the other hand, is difficult to achieve long-term control due to the strong regeneration ability and rapid spread of microchamomile. Therefore, the exploration of sustainable control technologies based on ecological regulation has become a research hotspot for invasive plant control.

[0003] Allelopathy is an adaptive mechanism developed by plants over a long period of evolution, occurring both within and across species. Studies suggest that invasive plants exert strong allelopathic inhibitory effects, leading to a decrease or loss of species diversity in their habitats. During its growth, chamomile releases allelopathic substances, causing other nearby plants and crops to experience slowed growth, nutrient deficiencies, or even death, while the chamomile itself continues to grow extensively. Current research on the allelopathic effects of chamomile growth focuses primarily on the seedling and vegetative stages. The primary control methods are manual removal and herbicide application, but these do not fundamentally address the problem of chamomile's recurring growth. As a key mechanism of chemical interactions between plants, allelopathy offers new avenues for biological control. Therefore, leveraging the principles of niche competition and allelopathic effects to select highly competitive plants and manage vacant niches through natural substitution (alternative control) offers the potential for sustainable ecological management of invasive species.

[0004] Callicarpa nudiflora Hook. & Arn., a member of the genus Callicarpa in the family Lamiaceae, grows in forests and thickets on hillsides, valleys, and along streams, ranging from plains to altitudes of 1,200 meters. Callicarpa nudiflora is a Lingnan specialty medicinal plant, and its leaves are used as medicine, boasting anti-inflammatory, anti-tumor, anti-dampness, and hemostatic properties. It is clinically used to treat inflammation caused by bacterial infections, acute infectious hepatitis, and bleeding from internal and external injuries. Research reports indicate that Callicarpa nudiflora leaves are rich in polyphenolic compounds, including flavonoids, iridoids, phenylethanoid glycosides, and phenolic acids, exhibiting various anti-inflammatory, antibacterial, and antioxidant properties. Summary of the Invention

[0005] To solve the above problems, the present invention provides a biological control method for inhibiting the growth of microchamomile, aiming to solve the problems of high difficulty in prevention and control, high economic investment, and serious harm to the ecological environment, native plant growth, and biodiversity.

[0006] The present invention provides a method for inhibiting the growth of microchamomile by using an extract from the leaves of Callicarpa nudiflora, comprising the following steps:

[0007] Obtain freeze-dried powder of Callicarpa nudiflora leaf extract;

[0008] a water-soluble reagent for preparing freeze-dried powder of Callicarpa nudiflora leaf extract;

[0009] The water-soluble agent is sprayed on the microchamomile plants.

[0010] Furthermore, the method of obtaining the Callicarpa nudiflora leaf extract includes collecting fresh Callicarpa nudiflora leaves, naturally air-drying, crushing, refluxing extraction with ethanol, filtering, concentrating, and freeze-drying to obtain the Callicarpa nudiflora leaf extract freeze-dried powder.

[0011] Furthermore, the leaves of the Callicarpa nudiflora are collected in January or July.

[0012] Furthermore, the amount of ethanol used is 8-15 times the weight of the air-dried Callicarpa oleifera leaves.

[0013] Furthermore, the reflux extraction conditions are: extraction in 70-90% ethanol twice, each time for 1-3 hours.

[0014] Furthermore, the freeze-dried powder of the Callicarpa nudiflora leaf extract is stored at 4°C.

[0015] Furthermore, the preparation of the water-soluble reagent refers to dissolving the freeze-dried powder of the Callicarpa nudiflora leaf extract in double-distilled water to prepare a solution with a mass concentration of 0.001-0.1%.

[0016] Furthermore, the spraying is carried out in January-February and April-May every year.

[0017] Furthermore, the spraying amount is 50-100 mL per square meter, and the spraying frequency is once a month.

[0018] Furthermore, the mass concentration of the water-soluble reagent prepared from the freeze-dried powder of the extract for spraying is 0.001-0.1%.

[0019] Furthermore, 0.1% of the extract is sprayed in January and February each year to inhibit the germination of microchamomile seeds; or, 0.1% or 0.01% of the extract of Callicarpa oleracea leaves picked in January is sprayed in April and May each year to inhibit the growth of adventitious roots at the microchamomile stem nodes.

[0020] An embodiment of the present invention further provides a microchamomile growth inhibitory preparation, which includes an extract of Callicarpa nudiflora leaves.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention uses extracts from the leaves of Callicarpa nudiflora to inhibit the growth of Microchamomile, which does not cause drug resistance problems like chemical agents, is environmentally friendly, does not damage the soil and ecosystem, and meets the requirements of sustainable development;

[0023] (2) The present invention sprays the extract of Callicarpa nudiflora leaves in January-February and April-May each year, respectively, to achieve phased and precise control of the seed germination stage and the adventitious root growth stage of the microchamomile, and more efficiently reduce the reproduction rate of the microchamomile;

[0024] (3) The freeze-dried powder provided by the present invention has a relatively simple preparation process, low cost, and is easy to store. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 These are the fresh leaves and fallen leaves of Callicarpa nudiflora;

[0027] Figure 2 The germination of Chamomile seeds after being treated with different concentrations of Callicarpa nudiflora leaf extracts;

[0028] Figure 3 The rooting of lateral branches of Microchamomile treated with different concentrations of Callicarpa nudiflora leaf extracts, among which the left picture is the fresh leaves XY group, and the right picture is the fallen leaves LY group;

[0029] Figure 4 The growth of potted Microchamomile treated with different concentrations of Callicarpa nudiflora leaf extract. The left picture is the fresh leaves XY group, and the right picture is the fallen leaves LY group. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The embodiment of the present invention provides a method for inhibiting the growth of Microchamomile using an extract from the leaves of Callicarpa nudiflora, comprising the following steps:

[0032] Obtain freeze-dried powder of Callicarpa nudiflora leaf extract;

[0033] a water-soluble reagent for preparing freeze-dried powder of Callicarpa nudiflora leaf extract;

[0034] The water-soluble agent is sprayed on the microchamomile plants.

[0035] Furthermore, the method of obtaining the extract of the leaves of Callicarpa nudiflora includes collecting fresh leaves of Callicarpa nudiflora, naturally air-drying, crushing, refluxing extraction with ethanol, filtering, concentrating, and freeze-drying to obtain freeze-dried powder of the extract of the leaves of Callicarpa nudiflora.

[0036] Furthermore, the leaves of the Callicarpa nudiflora are collected in January or July.

[0037] Furthermore, the amount of ethanol used is 8-15 times the weight of the air-dried Callicarpa oleifera leaves.

[0038] Furthermore, the reflux extraction is performed under the following conditions: extracting twice in 70-90% ethanol, each time for 1-3 hours; preferably, 75% ethanol is used for extraction.

[0039] Furthermore, the freeze-dried powder of the Callicarpa nudiflora leaf extract is stored at 4°C.

[0040] Furthermore, the preparation of the water-soluble reagent refers to dissolving the freeze-dried powder of the Callicarpa nudiflora leaf extract in double-distilled water to prepare a solution with a mass concentration of 0.001-0.1%.

[0041] Furthermore, the spraying is carried out in January-February and April-May every year.

[0042] Furthermore, the spraying amount is 50-100 mL per square meter, and the spraying frequency is once a month.

[0043] Furthermore, the mass concentration of the water-soluble reagent prepared from the freeze-dried powder of the extract for spraying is 0.001-0.1%.

[0044] Studies have found that the seeds of chamomile in South my country usually germinate gradually in January and February, and the stem nodes of chamomile have a strong reproductive ability in April and May. This application applies chamomile growth inhibitory agents of different concentrations in stages in January and February and April and May, which can prevent and control the growth and reproduction of chamomile to the greatest extent.

[0045] Furthermore, 0.1% of the extract was sprayed in January and February each year to inhibit the germination of microchamomile seeds.

[0046] Furthermore, the extract of Callicarpa oleracea leaves picked in January with a mass concentration of 0.1% or 0.01% is sprayed in April and May each year to inhibit the growth of adventitious roots at the nodes of Microchamomile.

[0047] In previous experiments, the inventors discovered that microchamomile is rarely seen in areas where Callicarpa nudiflora is found in natural communities, suggesting a possible allelopathic antagonism between the two. Based on this, the inventors conducted a systematic physiological and ecological experiment to investigate the inhibitory effects of a 75% ethanol extract from Callicarpa nudiflora leaves on microchamomile seed germination, stem node rooting, and potted plant growth. Combined with rhizosphere soil microbiome analysis, the inventors revealed the potential ecological mechanisms of its allelopathic effects, aiming to provide a theoretical basis and technical support for the ecological prevention and control of microchamomile.

[0048] The following is an explanation with reference to specific embodiments:

[0049] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. The materials, reagents, etc. used in the following examples are all commercially available, unless otherwise specified. Techniques not described in detail are performed according to standard methods well known to those skilled in the art.

[0050] Example 1 Preparation of freeze-dried powder of fresh leaf extract of Callicarpa nudiflora

[0051] Fresh leaves of Callicarpa nudica were collected from Shenzhen Xianhu Botanical Garden and air-dried. One kilogram of these air-dried leaves were crushed and extracted twice with 75% ethanol at a 1:10 ratio of reflux, each time for 2 hours. The combined extracts were filtered and concentrated under reduced pressure on a rotary evaporator. The ethanol was recovered to obtain the extract, which was then freeze-dried to obtain a lyophilized powder. The lyophilized powder was stored at 4°C until later use.

[0052] Example 2 Inhibitory effect of Callicarpa nudiflora fresh leaf extract on germination of Chamomile seeds

[0053] 1. Dosage regimen

[0054] Set up high, medium and low dose administration groups of Callicarpa nudiflora, and distilled water as blank control group. The extract freeze-dried powder was prepared into aqueous solutions with different mass concentrations of high, medium and low, that is, 1 mg·mL -1 , 0.1mg·mL -1 , 0.01mg·mL -1 An aqueous solution is used as the treatment liquid.

[0055] 2. Micro-chamomile seed preparation

[0056] Three layers of quantitative filter paper were placed in a 9-cm-diameter Petri dish. The dish was first moistened with 4 mL of distilled water. Fifty uniformly sized, plump, and fully mature seeds of the genus Chamomile were then picked with tweezers and evenly arranged. Three gradient concentration treatment groups were assigned according to the dosing schedule, with 3 mL of treatment solution added to each dish. The CK group (control group) was treated with distilled water, with three replicates per group. After treatment, the filter paper in each dish was kept moist. A layer of qualitative filter paper was placed over the seeds, followed by a layer of plastic wrap with uniformly punctured holes. The seeds were then incubated under fluorescent light with a 12 / 12-hour photoperiod. The room temperature was maintained at approximately 25°C. Germination was observed and recorded daily (defined as >2 mm breakthrough of the seed coat). An appropriate amount of treatment solution was added every three days to ensure the dish was moist. Recordings were continued for 14 days, and germination rate, germination potential, germination index, and allelopathic effects were measured.

[0057] 3. Test index determination

[0058] Germination rate: GR = (number of germinated seeds / total number of test seeds) × 100% (3-1)

[0059] Germination potential: GE = (number of seeds germinated within the specified time / number of test seeds) × 100% (3-2)

[0060] Germination index: GI = ∑(Gt / Dt) (3-3)

[0061] Where Gt: number of germinations at time t(d); number of culture days D(d).

[0062] The allelopathic effect test method proposed by Williamson is used, and the allelopathic effect index (RI) is:

[0063] RI=T / C-1 (when T<C) (3-4)

[0064] Where: C is the control value, T is the treatment value. When RI>0, it indicates a promoting effect; when RI<0, it indicates an inhibitory effect.

[0065] The absolute value of RI represents the intensity of allelopathic effect. RIGR, RIGE and RIGI are the allelopathic effect indices of germination rate, germination potential and germination index respectively.

[0066] Allelopathic effect (SE): Evaluated using the average value of the RI of the above three test items.

[0067] SE=(RIGR+RIGE+RIGI) / 3 (3-5)

[0068] 4. Results and analysis of germination of microchamomile seeds

[0069] The IBM SPSS one-way ANOVA test was used to test the significance of the differences in each indicator. At the same time, origin was used for graphical analysis. A comprehensive descriptive analysis was performed to evaluate the allelopathic inhibitory effect of Callicarpa oleracea extract on the germination of Microchamomile seeds, that is, the strength of the allelopathic effect.

[0070] 4.1 Analysis of physiological indicators

[0071] Table 1 Effects of different concentrations of Callicarpa nudiflora leaf extract on germination of Chamomile seeds

[0072] deal with Germination rate (%) Germination potential (%) Germination index water 32.00±2.00a 28.00±4.00a 3.73±0.62a 0.1％ 7.33±4.16c 6.67±5.03c 0.96±0.59c 0.01％ 24.67±6.43ab 21.33±5.77ab 2.96±1.21ab 0.001％ 18.00±3.46b 16.00±3.46b 2.05±0.24bc

[0073] Note: The data in the table are mean ± standard deviation. Different lowercase letters in the same column indicate significant differences (P < 0.05).

[0074] Table 1 shows the effects of Callicarpa nudiflora leaf extract on the germination rate of Chamomile seeds. One-way ANOVA analysis revealed significant differences in the germination rate, germination potential, and germination index between the control group (water) and the Callicarpa nudiflora leaf extract at concentrations of 0.1% and 0.001% (P < 0.05). The inhibitory effect at 0.1% reached a highly significant level (P < 0.01), while the inhibitory effect at 0.01% was not significant (P = 0.07 > 0.05). Comparative analysis revealed that the 0.1% concentration was the most effective treatment.

[0075] 4.2 Allelopathic index analysis

[0076] Table 2 Allelopathic effects of different concentrations of 75% ethanol extract of Callicarpa nudiflora on Chamomile

[0077] deal with RIGR RIGE RIGI SE 0.1％ -0.77±0.12c -0.76±0.18c -0.74±0.16c -0.76±0.15c 0.01％ -0.23±0.20ab -0.24±0.21ab -0.20±0.33ab -0.22±0.25ab 0.001％ -0.44±0.10b -0.43±0.12b -0.45±0.06bc -0.44±0.10b

[0078] Note: The data in the table are mean ± standard deviation. Different lowercase letters in the same column indicate significant differences (P < 0.05).

[0079] Based on the germination test results, further analysis of the germination rate, germination potential, and germination index of C. nudiflora seeds was performed, as shown in Table 2. Smaller values ​​indicate more significant inhibitory effects. Table 2 shows that the allelopathic effect index (SE) of the fresh leaf extract of C. nudiflora, derived from the three different indices (RIGR, RIGE, and RIGI), all showed inhibitory effects. Significant differences (P < 0.05) were observed between the mass concentrations of 0.1%, 0.01%, and 0.001%, with the 0.1% concentration exhibiting the strongest inhibitory effect, reaching an SE of -0.76. The allelopathic effects of the three concentrations on C. nudiflora were ranked in the order of 0.1% > 0.001% > 0.01%, with consistent inhibitory trends across all indicators. This suggests that the C. nudiflora leaf extract exhibits a strong allelopathic effect on C. nudiflora, and that the allelochemicals contained therein can significantly inhibit the germination of C. nudiflora seeds.

[0080] Example 3 Inhibitory effect of Callicarpa nudiflora leaf extract on rooting of Chamomile stem nodes in hydroponic culture

[0081] 1. Experimental Design

[0082] Lyophilized powder extracts of Callicarpa nudiflora leaves collected in January and July 2024 were prepared into two treatment solutions: a high concentration (0.1%) (H) and a low concentration (0.01%) (L), designated LY-H, LY-L, XY-H, and XY-L, respectively. A blank control group, designated CK, was prepared using distilled water. Aqueous solutions were prepared and tested in three scenarios: seed germination, hydroponic rooting of stem sections, and potted plants. Soil from the potted plants was analyzed for rhizosphere microbial communities.

[0083] Table 3 Experimental design groups

[0084]

[0085] 2. Hydroponic Rooting Test

[0086] Collect microchamomiles with good growth and uniform stem length, and cut the test materials according to three sections. Place the cut microchamomile stems in conical flasks, with 5 stems in each flask. Add 500mL of four treatment solutions, LY-H, LY-L, XY-H, and XY-L, and 500mL of distilled water to each conical flask, respectively, and cover 2 sections with water. Set up 3 replicates for each group. Each treatment was placed under laboratory fluorescent light and cultured according to a 12 / 12 hour photoperiod. The indoor temperature was kept constant at 25°C. Observe and record the rooting situation every day (root length > 0.5cm is the rooting standard) for 14 consecutive days.

[0087] 3. Test index determination

[0088] Same as Example 2.

[0089] 4. Rooting results and analysis of microchamomile stem nodes in hydroponic culture

[0090] 4.1 Analysis of physiological indicators

[0091] Microchamomile can produce new plants through rooting at the stem nodes, achieving asexual reproduction. The effects of Callicarpa nudiflora leaf extract on rooting at the stem nodes of Microchamomile are shown in Table 4. As can be seen in Table 4, the rooting rates of all four treatment groups were lower than those of the CK group, but the differences were not significant. The XY-H and LY-H treatments had the lowest rooting rates (73.33% ± 30.55 and 73.33 ± 23.09, respectively). Comparison of the root counts among the four treatment groups revealed that the XY-H and LY-H groups had lower root counts than the CK group, with the XY-H group showing the most significant inhibitory effect (2.167 ± 0.764), reaching a significant difference (P < 0.05). Analysis of root length among the four treatment groups revealed that the XY-H and LY-H groups had significantly lower root counts than the CK group, with XY-H showing the greatest effect (1.560 ± 0.744). From the perspective of mass concentration, the 0.1% treatment concentration (XY-H, LY-H) had an inhibitory effect on the rooting of microchamomile stem nodes in hydroponic culture, and the rooting rate, root number and root length were generally lower than those of the CK group. Among them, the root length of XY-H and LY-H showed significant differences compared with the CK group (p<0.05). The XY-H treatment also had a significant inhibitory effect on the root number of stem nodes (p<0.05). The 0.01% treatment concentration (XY-L, LY-L) had no obvious inhibitory effect on the rooting of microchamomile stem nodes in hydroponic culture.

[0092] Table 4 Effects of Callicarpa nudiflora leaf extract on rooting of Chamomile stem nodes

[0093]

[0094] Note: The data in the table are mean ± standard deviation. Different lowercase letters in the same column indicate significant differences (P < 0.05).

[0095] 4.2 Allelopathic index analysis

[0096] Table 5 shows the comprehensive allelopathic effect analysis of the four treatment groups. Based on the data in this table, the 0.1% mass concentration treatments (XY-H and LY-H) inhibited root number, root length, and SE. The absolute values ​​of root number, root length, and SE for XY-H were 0.687, 0.576, and 0.632, respectively, all exceeding those for LY-H, indicating that XY-H had a greater inhibitory effect than LY-H. The 0.01% mass concentration treatments (XY-L and LY-L) positively promoted rooting in hydroponic microchamomile sections but had no inhibitory effect. This suggests that a 0.1% mass concentration aqueous solution of Callicarpa nudica leaf extract inhibited rooting in hydroponic microchamomile sections, with XY-H having the greatest inhibitory effect.

[0097] Table 5 Effects of different treatments on the allelopathic effects of Callicarpa serrata leaf extracts

[0098]

[0099] Note: In the allelopathic index, + value indicates promotion, - value indicates inhibition, and the absolute value indicates the strength of the allelopathic effect.

[0100] Example 4 Inhibitory effect of Callicarpa nudiflora fresh leaf extract on Chamomile potted plants

[0101] 1. Experimental Design

[0102] The experimental group design is the same as that in Example 3.

[0103] 2. Microchamomile potted plant experiment

[0104] Prepare a substrate using a 1:1 volume ratio of garden soil to river sand. Sow chamomile seeds in a seed tray, 10 seeds per hole. Place in a shade shed and water occasionally with tap water to await germination. After 30 days, select chamomiles with consistent growth trends and plant them in separate pots, 3 plants per pot. Transfer and cultivate indoors under a 12 / 12 hour photoperiod and at a constant temperature of 25°C. Water with tap water for two weeks to allow for acclimatization. Subsequently, irrigate each pot with 1000 mL of treatment solution or distilled water every 7 days, and record growth for 45 consecutive days.

[0105] 3. Test index determination

[0106] Same as Example 2.

[0107] 4. Microchamomile potted results and analysis

[0108] 4.1 Analysis of physiological indicators

[0109] Furthermore, an experiment was conducted to test the effects of Callicarpa nudica leaf extract on the growth of potted microchamomile plants. The physiological parameters of the potted plants in the CK group and the four treatment groups were statistically summarized and analyzed for significant differences (Table 6). Table 6 shows that the leaf number of each treatment group, from low to high, ranked LY-L < LY-H < XY-L < CK < XY-H. The LY-L group had the fewest leaves (19.00 ± 4.47), indicating that LY-L inhibited leaf initiation. The LY-L and XY-H groups showed no significant differences from the CK group, and the other groups showed no significant differences from the CK group. The total bolt length, from short to long, ranked LY-H < LY-L < XY-L < XY-H < CK. The LY-H group had the shortest bolt length (54.13 ± 19.68), with a significant difference from the CK group (p < 0.05), indicating that LY-H inhibited microchamomile bolting. Root length, from short to long, followed the order XY-L < XY-H < CK < LY-L < LY-H, with XY-L having the shortest roots (17.58 ± 3.04), but no significant differences were found between the groups and the CK group. Leaf fresh weight, from light to heavy, followed the order LY-L < CK < XY-L < XY-H < LY-H, with the LY-L group having the lightest leaves (3.00 ± 1.07), but no significant differences were found between the groups. Stem weight in all four treatment groups was less than that in the CK group, following the order LY-L < LY-H < XY-L < XY-H < CK, with the LY-L group having the lightest stems (1.23 ± 0.20). Significant differences were found between the LY-L and LY-H groups and the CK group (p < 0.05), indicating that the Callicarpa nudiflora extract inhibited stem growth. The order of root weight from light to heavy was CK<LY-L<XY-L<LY-H<XY-H. All four treatment groups showed an increase in weight compared to the CK group, but there were no significant differences between the groups and the CK group. The order of fresh weight from light to heavy was LY-L<CK<XY-L<LY-H<XY-H, with the LY-L group being the lightest (7.26±1.64), but there were no significant differences between the groups and the CK group. In summary, the extract from the leaves of Callicarpa nudica had a significant inhibitory effect on the total length and stem weight of potted microchamomile seedlings. LY-H had the best effect on inhibiting the total length of microchamomile bolting, with the length reduced by 50.00% compared to the CK group. LY-L had the best effect on inhibiting the stem weight, with the stem weight reduced by 40.30% compared to the CK group.

[0110] Table 6 Effects of Callicarpa nudiflora leaf extract on physiological parameters of Chamomile potted seedlings

[0111]

[0112] Note: The physiological index data in the table are mean ± standard deviation. Different lowercase letters in the same column indicate significant differences (P < 0.05).

[0113] 4.2 Allelopathic index analysis

[0114] Combined with the results of physiological index analysis, allelopathic effects were further analyzed for the significant differences in total bolting length and stem weight, as shown in Table 7. Table 7 shows that the allelopathic effect of total bolting length RI, from strong to weak, was LY-H > LY-L > XY-L > XY-H, with the LY-H group having the strongest inhibitory effect (-0.500); the allelopathic effect of stem weight RI, from strong to weak, was LY-L > LY-H > XY-L > XY-H, with the LY-L group having the strongest inhibitory effect (-0.403); and the allelopathic effect of SE, from strong to weak, was LY-H > LY-L > XY-L > XY-H, with the LY-H group having the strongest inhibitory effect (-0.441). In summary, the physiological index data of the LY treatment group were generally lower than those of the XY group. The inhibitory effect of LY on the growth of microchamomile was stronger than that of XY. In addition, LY showed a significant inhibitory effect on the total length and stem weight of potted microchamomile, and the inhibitory effect became more obvious with the increase of concentration.

[0115] Table 7 Allelopathic effects of different treatments on Chamomile potted seedlings

[0116]

[0117] Note: In the table, + value indicates promotion effect, - value indicates inhibition effect, and the absolute value indicates the magnitude of effect.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for inhibiting the growth of microchamomile using extracts from the leaves of Callicarpa nudiflora, comprising the following steps: Obtain freeze-dried powder of Callicarpa nudiflora leaf extract; a water-soluble reagent for preparing freeze-dried powder of Callicarpa nudiflora leaf extract; The water-soluble agent is sprayed on the microchamomile plants.

2. The method according to claim 1, wherein The method for obtaining freeze-dried powder of Callicarpa nudiflora leaf extract comprises collecting fresh leaves of Callicarpa nudiflora, naturally air-drying, crushing, extracting with ethanol by refluxing, filtering, concentrating, and freeze-drying to obtain the freeze-dried powder of Callicarpa nudiflora leaf extract.

3. The method according to claim 2, wherein The leaves of Callicarpa nudiflora are collected in January or July.

4. The method according to claim 2, wherein The amount of ethanol used is 8-15 times the weight of the air-dried Callicarpa nudiflora leaves.

5. The method according to claim 2, wherein The reflux extraction conditions are as follows: extracting twice in 70-90% ethanol, each time for 1-3 hours, and the obtained freeze-dried powder of the Callicarpa nudiflora leaf extract is stored at 4°C.

6. The method according to claim 1, wherein The preparation of the water-soluble reagent refers to dissolving the freeze-dried powder of the Callicarpa nudiflora leaf extract in double-distilled water to prepare a solution with a mass concentration of 0.001-0.1%.

7. The method according to claim 1, wherein The spraying time is from January to February and from April to May each year, the spraying amount is 50-100 mL per square meter, and the spraying frequency is once a month.

8. The method according to claim 1, wherein The mass concentration of the water-soluble reagent prepared from the freeze-dried powder of the extract for spraying is 0.001-0.1%.

9. The method according to claim 7, wherein Spraying 0.1% of the extract in January and February each year is used to inhibit the germination of microchamomile seeds; alternatively, spraying 0.1% or 0.01% of the extract of Callicarpa nudiflora leaves picked in January in April and May each year is used to inhibit the growth of adventitious roots at the microchamomile stem nodes.

10. A microchamomile growth inhibitory preparation comprising an extract of Callicarpa nudiflora leaves.

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