Curcuma longa carbon dots and application of preparation thereof in growth promotion and bacteriostasis of cotton

Abstract

The invention relates to application of turmeric carbon dots and a preparation thereof in growth promotion and bacteriostasis of cotton, and aims to overcome the defects of limited bacteriostasis effect, photosynthesis inhibition and ecological damage of existing chemical agents in prevention and treatment of cotton verticillium wilt. According to the method, a biomass-sourced turmeric carbon dot (CDs) solution (with the concentration of 25-100 mg / L, preferably 50 mg / L) is applied in a foliage spraying (seedling stage disease-resistant preparation) or soil root irrigation (blocking pathogenic bacteria infection) dual mode, mycelial growth and spore germination of verticillium dahliae are directly inhibited, meanwhile, acquired resistance (SAR) of a cotton system is activated, and root development and photosynthesis in a seedling stage are promoted. According to the method, organic unification of'prevention effect improvement, growth promotion and ecological safety 'of the nano material in prevention and control of soil-borne diseases is realized, and revolutionary technical support is provided for green agriculture.

Description

Technical Field

[0001] This invention relates to the field of crop disease control technology, and in particular to the application of turmeric carbon dots and their preparations in promoting growth and inhibiting bacteria in cotton. Background Technology

[0002] Cotton, as one of the world's most important fiber crops and strategic resources, has developed a diversified industrial chain encompassing fiber, oilseeds, protein, ecology, and energy. Cotton Verticillium wilt, a soil-borne fungal disease, is caused by the pathogen *Verticillium dahliae*, which can survive in the soil for over 10 years, affecting 50% of cotton fields in China and resulting in annual economic losses of 1.5 to 2 billion yuan. Therefore, *Verticillium dahliae* (… Verticillium dahliae Verticillium wilt, caused by cotton wilt, has become a key disease restricting the development of the cotton planting industry. However, existing cotton Verticillium wilt control technologies and measures have significant shortcomings: ①Limitations of chemical control: Chemical agents (such as thiophanate-methyl) are prone to residues and have limited efficacy, while soil fumigation is costly and disrupts the ecological balance; ②Bottlenecks in disease-resistant breeding: The scarcity of natural resistance sources leads to a traditional breeding cycle of 8-10 years, and existing disease-resistant varieties suffer from resistance decline; ③Excessively long crop rotation cycle: It takes 3-5 years of crop rotation to reduce soil microbial biomass, which contradicts the intensive planting model.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] This invention addresses the technical problems of limited antibacterial effect, disruption of photosynthesis, and poor ecological compatibility in the control of cotton Verticillium wilt by existing chemical agents. It uses turmeric biomass carbon dots (CDs) as a plant disease resistance inducer. Through a dual synergistic mechanism (directly inhibiting the mycelial growth and spore germination of Verticillium dahliae + activating the salicylic acid-mediated systemic acquired resistance (SAR) pathway), it achieves synergistic enhancement of disease control and plant growth, breaking through the bottleneck of the traditional "growth-defense trade-off".

[0005] According to one aspect of this disclosure, the use of turmeric carbon dots in any of the following or in the preparation of formulations having any of the following functions: (1) Inhibits the germination of Verticillium dahliae conidia; (2) Inhibits the mycelial growth of Verticillium dahliae; (3) Enhance cotton's resistance to Verticillium dahliae; (4) Inducing the response gene of SA in cotton PR1, PR2, PR3, PR8, PR14 or / and PR15 The expression of [something] is used to acquire resistance; (5) Control of cotton Verticillium wilt (6) Increase cotton seedling biomass; (7) Promotes root development in cotton seedlings; (8) Increase cotton plant height, number of long roots, number of lateral roots, chlorophyll content and / or dry weight.

[0006] In some embodiments of this disclosure, the concentration of the turmeric carbon dots applied is 25-100 mg / L.

[0007] In some embodiments of this disclosure, the concentration of the turmeric carbon dots applied is 40-60 mg / L.

[0008] In some embodiments of this disclosure, foliar spraying or soil drenching is performed during the cotton seedling stage.

[0009] According to another aspect of this disclosure, a cotton growth promoter and antibacterial agent is provided, containing an effective amount of 25-100 mg / L of turmeric carbon dots and an agriculturally acceptable carrier.

[0010] According to another aspect of this disclosure, a method for controlling cotton Verticillium wilt is provided, in which turmeric carbon dots are used as: Foliar fertilizer during seedling stage: Spray with a turmeric carbon dot solution at a concentration of 25-100 mg / L daily for 4-6 consecutive days; or Root dipping agent: Before transplanting, soak the cotton seedling roots in a turmeric carbon point solution with a concentration of 25~100 mg / L for 10~20 min.

[0011] This invention provides carbon dots (CDs) based on turmeric biomass and their application in controlling cotton Verticillium wilt. It overcomes the limitations of existing technologies through a triple synergistic mechanism, and the specific technical effects are as follows: 1. Dual protection through direct antibacterial action and resistance induction Inhibition of pathogen proliferation: Appropriate concentrations (such as 50 mg / L) of turmeric CDs can significantly inhibit the mycelial growth and spore germination of Verticillium dahliae, thus blocking the initial infection; Activation of systemic resistance (SAR): Induces a significant increase in salicylic acid (SA) content in cotton roots; upregulates SA pathway marker genes ( PR1, PR2, PR3 Etc. expression level P <0.01), forming a long-lasting broad-spectrum disease resistance.

[0012] 2. Growth-Defense Synergistic Mechanism Promotes seedling growth: Treatment with appropriate concentrations (e.g., 50 mg / L) of CDs significantly improves key indicators during the seedling stage: root length, plant height, and chlorophyll content, enhancing photosynthetic efficiency; increased dry weight accumulation provides carbon and energy for the synthesis of disease-resistant substances.

[0013] Breaking the "growth-defense" trade-off: chlorophyll enhancement and SA accumulation form a positive feedback loop (photosynthetic products → SA synthesis → enhanced resistance → reduced energy loss), achieving simultaneous optimization of disease resistance and growth potential.

[0014] 3. Flexible application methods and environmental compatibility Multiple application methods: It can be applied as a foliar fertilizer or used for root irrigation, both of which significantly reduce the disease index; Environmentally friendly: Biomass-derived CDs are completely degraded, with no risk of chemical residues; The concentration window is clearly defined: 50 mg / L is the optimal effective concentration. High concentrations (≥100 mg / L) inhibit growth, while low concentrations (≤25 mg / L) have insufficient disease resistance.

[0015] 4. Economic benefits and industry adaptability Differential regulation between germination and seedling stages: Although it temporarily inhibits seed germination rate, it promotes growth in the seedling stage and supports targeted application (foliar / root irrigation) during the seedling stage. Value across the entire industry chain: reducing yield losses caused by Verticillium wilt (e.g., in Xinjiang cotton-growing areas, losses are expected to be recovered by 15-20%), and ensuring the quality of cotton fiber and the stability of cottonseed by-product supply. Attached Figure Description

[0016] Figure 1 In this embodiment of the application, turmeric carbon dots can inhibit the mycelial growth and conidial germination of Verticillium dahliae; wherein, A: colony images of Verticillium dahliae on PDA and CM plates; B: spore germination morphology under laser confocal microscopy; C: statistics on the mycelial growth inhibition rate of Verticillium dahliae; D: determination of the conidial germination rate of Verticillium dahliae.

[0017] Figure 2 In this embodiment of the application, turmeric carbon dots can improve the resistance of cotton to Verticillium dahliae; wherein, A: growth phenotype of cotton in different treatment groups; B: browning of vascular bundles of cotton in different treatment groups; C: recovery of fungal hyphae on the stems of cotton in different treatment groups; D: determination of disease index of cotton in different treatment groups; E: determination of fungal biomass of cotton in different treatment groups.

[0018] Figure 3 In this embodiment of the application, turmeric carbon dots activate cotton “SAR” to improve its resistance to Verticillium dahliae; wherein, A: fungal biomass in local roots and distal leaves of cotton; B: determination of salicylic acid (SA) content in cotton roots of different treatment groups; C: determination of relative expression levels of salicylic acid (SA) pathway response genes.

[0019] Figure 4The following are examples of the effects of turmeric carbon dots on cotton seed germination and cotton seedling growth in this application: A: Measurement of cotton seed bud length in different treatment groups; B: Measurement of cotton seed germination rate in different treatment groups; C: Phenotypic diagram of cotton seedling growth in different treatment groups; D: Phenotypic diagram of cotton seedling leaves in different treatment groups. Detailed Implementation

[0020] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The turmeric-derived carbon dots (Cur-CDs) involved in the following examples are prepared by hydrothermal method using natural turmeric as the carbon source (bulk, powder, or residue). Their surface is rich in functional groups such as hydroxyl, carboxyl, and pyridine nitrogen, exhibiting good water solubility and environmental friendliness. For the specific preparation method, please refer to patent document CN116986582A.

[0022] Example 1: Inhibitory effect of turmeric carbon dots on mycelial growth and conidial germination of Verticillium dahliae (I) Experimental Materials and Methods 1. Preparation of Turmeric Carbon Dot Solution (CDs) The preparation method of the turmeric carbon dot solution is based on patent document CN116986582 A. The prepared turmeric carbon dot solid is dissolved in dimethyl sulfoxide (DMSO) to prepare a solution with a concentration of 1×10⁻⁶. 5 The stock solution was prepared at a concentration of mg / mL and then diluted with deionized water to the following working concentrations: 10, 25, 50, 100, 250, and 500 mg / L.

[0023] 2. Strain activation and conidia preparation (1) Activation of strains: Verticillium dahliae preserved on slant culture ( Verticillium dahliae Inoculated onto potato dextrose agar (PDA) medium and activated in the dark at 28 °C for 7 days.

[0024] (2) Mycelial growth experiment: Take the edge of the activated colony block with a 3 mm diameter punch, inoculate it on a fresh PDA plate, and incubate in the dark at 28 ℃ for 7 days. Measure the colony diameter daily.

[0025] (3) Conidia preparation: 30 pieces (3×3 mm) of activated colonies were cut and inoculated into Czapek-Dox medium, and cultured at 28 ℃ and 200 rpm for 5 days with shaking. After filtration through sterile filter cloth, the concentration of the spore suspension was adjusted to 1×10⁻⁶ with sterile water. 6 spores / mL.

[0026] 3. Experiment on the inhibition of mycelial growth by CDs (1) Take 1 mL of conidial suspension and mix it with 1 mL of 50 mg / L CDs solution. After treating at 28 °C for 30 min, take 5 μL and inoculate it onto PDA plate (mycelial growth substrate) and CM plate (complete culture medium).

[0027] (2) The control group (CK) used an equal volume of sterile water instead of CDs solution, and the other operations were the same.

[0028] (3) After incubation at 28 ℃ for 14 days, the colony diameter was measured using the cross-sectional method. D c / D t The inhibition rate is calculated using the formula: Inhibition rate (%) = [( D c - D t ) / D c ×100%; in, D c The colony diameter is the control group. D t The diameter of the colonies in the treatment group.

[0029] 4. Experiment on the inhibition of conidial germination by CDs (1) Inoculate 1 mL of spore suspension treated with 50 mg / L CDs into a centrifuge tube containing 4 mL of PDB medium and culture at 28 ℃ and 200 rpm.

[0030] (2) The germination rate of the control group was examined under a microscope every hour. When the germination rate of the control group was >90%, the spore germination morphology was observed under a laser confocal microscope. Figure 1 B).

[0031] (3) Formula for calculating germination rate: Germination rate (%) = N g / N t × 100%; among which, N g Represents the number of germinating conidia. N t This represents the total number of conidia.

[0032] (II) Experimental Results 1. The inhibitory effect of CDs on mycelial growth like Figure 1As shown in A and 1C, after treatment with 50 mg / L CDs, the mycelial inhibition rate on PDA plates reached 9.2%, and the inhibition rate on CM plates reached 4.1%, significantly inhibiting colony expansion. P <0.05).

[0033] 2. Inhibitory effect of CDs on conidial germination Laser confocal microscopy observation ( Figure 1 B) and germination rate statistics ( Figure 1 (D) indicates that the spore germination rate in the CDs-treated group decreased to 25.7%, which was significantly lower than that in the control group. P <0.05).

[0034] The above results indicate that 50 mg / L turmeric carbon dots can simultaneously inhibit the mycelial growth and conidial germination of Verticillium dahliae.

[0035] Example 2: The inducing effect of turmeric carbon dots on cotton resistance to Verticillium dahliae disease. Based on the results in Example 1, where 50 mg / L turmeric carbon dots (CDs) inhibited the mycelial growth and spore germination of *Verticillium dahliae*, this example aims to further evaluate whether CDs can enhance the systemic resistance of cotton to this pathogen. The pot experiment was designed as follows: 1. Experimental Design Experimental group (CDs treatment group): Cotton seedlings at the two-leaf stage were sprayed evenly with different concentrations of turmeric carbon point solution (10, 25, 50, 100, 250, 500 mg / L) daily for 5 consecutive days.

[0036] Positive control group (pathogen inoculation group, Control): Sprayed with the same volume of sterile water as the experimental group daily for 5 days.

[0037] Negative control group (Mock group): Sprayed with the same volume of sterile water as the experimental group daily for 5 days, without inoculation with Verticillium dahliae.

[0038] 2. Pathogen inoculation After completing the 5-day spraying treatment: Carefully dig up the cotton seedlings and thoroughly rinse the roots with sterile water. Immerse the seedling roots in a suspension of Verticillium dahliae conidia (1×10⁻⁶). 6 Soak the seedlings in a solution of 1 spore / mL for 15 minutes. After inoculation, transplant the seedlings back into flowerpots.

[0039] Mock group seedlings were treated only with sterile water immersion and did not come into contact with spore suspension. All treatment group seedlings were further cultured in a greenhouse.

[0040] 3. Disease assessment indicators (1) Phenotypic observation: The overall growth status was photographed 14 days after inoculation. Figure 2 A).

[0041] (2) Grading of vascular bundle browning: The stem is longitudinally cut open and graded according to the following criteria: - Grade 0: No browning; - Level 1: Browning area < 1 / 3; - Level 2: Browning area 1 / 3 to 2 / 3; - Level 3: Browning area > 2 / 3; The disease index is calculated as follows: Disease index = [(∑ level n × number of diseased plants at that level) / total number of plants surveyed] × 100.

[0042] (3) Detection of fungal colonization: Morphological observation: Stem segments were cut and placed on PDA plates. After incubation at 28 ℃ for 3 days, the mycelial recovery was observed. Figure 2 C).

[0043] Molecular quantification: DNA was extracted from the stem using the CTAB method, and qPCR was used to detect *Verticillium dahliae*. VdElf Relative gene expression levels (internal reference: cotton) Gh18S ), using 2 -ΔΔCt The method is calculated (primers are shown in Table 1).

[0044] Table 1 Primer sequence listing .

[0045] 4. Experimental Results (1) Cotton growth phenotype and vascular bundle lesions like Figure 2 As shown in Figures AB, 14 days after inoculation, the 10 mg / L and 500 mg / L CDs treatments showed no significant relief of cotton Verticillium wilt symptoms. In contrast, cotton plants in the 25, 50, 100, and 250 mg / L CDs treatments exhibited milder wilting and yellowing symptoms. Plants in the 50 mg / L CDs treatment group were robust, with only slight browning of the vascular bundles (grade 1); while plants in the control group were significantly stunted, with severe browning of the vascular bundles (grade 3). The severity of lesions in the 25, 100, and 250 mg / L treatment groups was intermediate between the two groups, while there was no significant difference between the 10 and 500 mg / L groups and the control group.

[0046] (2) Disease index and fungal colonization analysis ① Disease index statistics: Compared with the positive control group, the disease index of the 25, 50, 100, and 250 mg / L CDs treatment groups was significantly lower. P<0.01). Among them, the disease index of the 50 mg / L CDs treatment group was the lowest, with an average of only 2.1; the average disease index of the positive control group (Control) was 3.8 ( Figure 2 D).

[0047] ② Fungal biomass determination: qPCR results showed that *Verticillium dahliae* was present in the cotton stem tissue of the 25, 50, 100, and 250 mg / L CDs treatment groups. VdElf The relative expression levels of genes (reflecting fungal biomass) were significantly lower than those in the positive control group. P <0.01); 50 mg / L CDs treatment group VdElf Gene expression levels were only 18.6% of the control group. Figure 2 E), the stem segment mycelial recovery experiment also showed a decrease in fungal colonization (E), Figure 2 C).

[0048] The above results indicate that treatment with appropriate concentrations (25–250 mg / L) of turmeric carbon dots (CDs) can effectively enhance the systemic resistance of cotton to Verticillium dahliae infection, significantly reduce the disease index, alleviate vascular bundle browning, and inhibit the colonization and spread of the pathogen in the vascular bundles. Among all tested concentrations, 50 mg / L CDs showed the most significant control effect against cotton Verticillium wilt.

[0049] Example 3: Molecular mechanism of turmeric carbon dot-induced systemic acquired resistance (SAR) in cotton Based on the results in Examples 1 and 2 that 50 mg / L turmeric carbon dots (CDs) can inhibit the growth of Verticillium dahliae and improve the disease resistance of cotton, this example aims to explore its mechanism of action, focusing on evaluating whether CDs enhance cotton's defense capabilities by activating the salicylic acid (SA)-mediated systemic acquired resistance (SAR) pathway.

[0050] 1. Experimental Design CDs treatment group: Two-leaf stage cotton seedlings were placed in Hoagland nutrient solution containing 50 mg / L CDs and cultured hydroponically for 5 days.

[0051] Control group: Cotton seedlings were hydroponically cultured in pure Hogland nutrient solution without CDs for 5 days (under the same conditions).

[0052] Pathogen inoculation: After 5 days of hydroponics, follow the root soaking method in Example 2, adjusting the concentration to 1×10⁻⁶. 6 A suspension of Verticillium dahliae conidia with 1 spore / mL was used to inoculate the roots of two groups of cotton seedlings.

[0053] 2. Sample Collection and Testing (1) Fungal biomass determination: Local roots and distal leaves were collected at 0 and 10 days after inoculation, respectively. DNA was extracted by CTAB method and detected by qPCR. VdElf Relative gene expression levels (method as in Example 1).

[0054] (2) SA content determination: 1 g of root tissue was taken 10 days after inoculation and the absorbance was measured at 450 nm wavelength using a microplate reader according to the instructions of the plant SA ELISA kit (Mlbio).

[0055] (3) Gene expression analysis: RNA was extracted from roots 10 days after inoculation, reverse transcribed into cDNA, and then the SA pathway marker genes were detected by qRT-PCR. PR1, PR2, PR3, PR8, PR14, PR15 The relative expression level of ) using 2 ⁻ΔΔCt Method calculation (internal reference:) Gh18S ).

[0056] 3. Experimental Results Fungal biomass distribution ( Figure 3 A): Ten days after inoculation, qPCR results showed that the relative biomass of Verticillium dahliae in the distal leaf tissue of cotton in the CDs-treated group was significantly lower than that in the control group, indicating that CDs treatment can effectively inhibit the systemic spread of pathogens in the plant.

[0057] Salicylic acid (SA) accumulation ( Figure 3 B): ELISA results showed that 10 days after inoculation, the SA content in the cotton root tissue of the CDs-treated group was significantly higher than that of the control group, suggesting that CDs treatment induced the accumulation of SA.

[0058] SA pathway gene expression activation ( Figure 3 C): qRT-PCR analysis showed that, compared with the control group, all detected SA pathway response marker genes in cotton roots of the CDs-treated group ( PR1 , PR2 , PR3 , PR8 , PR14 , PR15 The expression levels of ) were significantly upregulated. P <0.01), clearly confirming that CDs processing strongly activates the SA signaling pathway.

[0059] In summary, treatment with 50 mg / L turmeric carbon dots (CDs) significantly induced the accumulation of salicylic acid (SA) in cotton roots and strongly activated the expression of key defense genes (PR genes) downstream of the SA signaling pathway. Increased SA levels and the widespread activation of defense genes mediated by this pathway are typical markers of systemically acquired resistance (SAR) in plants. Therefore, this example demonstrates that turmeric carbon dots enhance cotton's resistance to Verticillium dahliae infection through the activation of the SA-mediated SAR pathway.

[0060] Example 4: The stage-specific effects of turmeric carbon dot solution on cotton growth Based on the evidence from Examples 1 to 3 that 50 mg / L turmeric carbon dots (CDs) can effectively inhibit Verticillium dahliae and activate the SAR resistance pathway in cotton, this example aims to systematically evaluate the potential impact of CDs on cotton seed germination and seedling growth, and provide a basis for its safety in field application.

[0061] 1. Experimental Design Experimental groups: CDs treatment group and control group (Control).

[0062] Seed germination experiment: 50 plump cotton seeds were collected from each group and treated in a 55 ℃ water bath for 15 min (to break dormancy / surface sterilization). CDs treatment groups: Seeds were sprayed evenly daily with different concentrations of CDs solution (10, 25, 50, 100, 250, 500 mg / L). Control group: Seeds were sprayed daily with an equal volume of sterile water. After 5 days of treatment, the germination rate and sprout length were recorded for each group.

[0063] Seedling growth experiment: The roots of healthy cotton seedlings with fully expanded cotyledons were rinsed with sterile water. They were then transplanted into Hoagland nutrient solution for pre-culture for 3 days.

[0064] After pre-culture, the CDs-treated group was transferred to Hogrange medium containing different concentrations of CDs (10, 25, 50, 100, 250, 500 mg / L) for 5 days; the control group was cultured in pure Hogrange medium for another 5 days.

[0065] After treatment, take photos of the overall phenotypic characteristics of the seedlings; measure the following seedling biomass indicators: plant height, root length, number of lateral roots, stem diameter, leaf area, chlorophyll content (based on the second true leaf), fresh weight, and dry weight.

[0066] 2. Experimental Results (1) Seed germination and early growth Figure 4A, B, Table 2): The effect of 50 mg / L CDs treatment on cotton seed germination rate and sprout length was not statistically different compared with the control group. P >0.05); Treatment with 100, 250, and 500 mg / L CDs significantly reduced germination rate and inhibited shoot elongation ( Figure 4 (A, B). In the 50 mg / L treatment group, germination potential, germination rate, germination index, and vigor index were all reduced; bud length increased slightly (9.02 ± 0.82 cm vs 8.70 ± 0.90 cm), while fresh weight and dry weight showed no significant changes.

[0067] (2) Seedling growth phenotype and biomass Figure 4 C, D, Table 3): Treatment with 10, 25, and 50 mg / L CDs had no significant negative impact on the overall phenotype of seedlings. Figure 4 C). Treatment with 100, 250, and 500 mg / L CDs inhibited seedling growth ( Figure 4 C), and the leaves of the 250 and 500 mg / L treatment groups showed obvious spots, suggesting that high concentrations of CDs may produce phytotoxicity. Figure 4 D). Compared with the control, the root length, number of lateral roots, plant height, chlorophyll content, and dry weight of the 50 mg / L treatment group were slightly increased, while the leaf area and fresh weight were slightly decreased, and the stem diameter remained unchanged.

[0068] Table 2 Cotton Seed Germination Indicators Group Control group 50 mg / L CDs Germination potential (%) 68.33±2.89 51.67±2.89 Germination rate (%) 80.00±0.00 56.67±5.77* Sprout length (cm) 8.70±0.90 9.02±0.82 Germination index 12.09±0.26 9.18±1.15 Vigor index 105.26±13.12 82.58±10.33 Fresh weight 0.27±0.03 0.32±0.03 Dry weight 0.04±0.01 0.04±0.01 Note: The mean ± standard deviation (± SD) was calculated for the three repeated experiments, and * indicates... P< 0.01.

[0069] Table 3. Determination of cotton biomass Group Control group 50 mg / L CDs Root length (cm) 20.68±2.77 22.36±1.76 Lateral root number 31.38±4.90 32.13±4.45 Stem diameter (cm) 0.20±0.02 0.20±0.02 Plant height (cm) 17.34±1.43 18.14±1.10 Chlorophyll content 31.53±1.59 32.71±1.10 Leaf area (cm 2 )]> 29.23±3.07 26.40±2.33 Fresh weight (g) 3.99±0.42 3.97±0.19 Dry weight (g) 0.40± 0.06 0.42±0.03 Note: Leaf area and chlorophyll content were measured based on the second true leaf.

[0070] 3. Key Indicator Analysis (1) Significance of seed germination indicators: Germination rate and germination index: reflect the seed germination process (dormancy breaking, water absorption and metabolism), a decrease suggests that CDs may inhibit seed vigor. Sprout length and vigor index (germination rate × sprout length): reflect the early growth vigor of seedlings, a decrease in vigor index indicates that CDs may affect morphogenesis.

[0071] (2) Significance of seedling growth indicators: Root length, number of lateral roots, and plant height: These reflect root development and above-ground growth. Increased levels suggest that CDs may promote nutrient / water absorption. Chlorophyll content: Increased levels may enhance photosynthetic efficiency and provide energy support for disease resistance responses (such as SA synthesis).

[0072] (3) “Growth-Defense Trade-off” Phenomenon: Plants often face the balance between the input of disease resistance resources and growth. This experiment found that during the germination period: although 50 mg / L CDs did not significantly inhibit bud growth, it significantly reduced the germination rate and vigor index, suggesting that there was a slight tendency for growth inhibition at this stage, which may be related to the effect of direct contact between seeds and CDs on initial metabolism; during the seedling stage: under the treatment of 50 mg / LCDs, multiple growth indicators (root length, plant height, chlorophyll, dry weight) showed an increasing trend, and no toxic phenotype was observed, indicating that CDs did not inhibit growth at this stage, and may even indirectly support the SAR activation (“growth-resistance synergy” potential) observed in Example 3 by promoting photosynthesis and root development.

[0073] In summary, 50 mg / L turmeric carbon dots (CDs) had no negative impact on cotton growth during the seedling stage, and multiple indicators showed positive trends. Combined with the significant disease resistance effects demonstrated in Examples 1 to 3, this concentration indicates application potential. High concentrations of CDs (≥100 mg / L) inhibited both cotton seed germination and seedling growth, and visible toxic symptoms (leaf spots) were produced at concentrations ≥250 mg / L.

[0074] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0075] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of its inventive concept. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. Application of turmeric carbon dots in any of the following or in the preparation of formulations having any of the following functions: (1) Inhibits the germination of Verticillium dahliae conidia; (2) Inhibits the mycelial growth of Verticillium dahliae; (3) Enhance cotton's resistance to Verticillium dahliae; (4) inducing the expression of a cotton SA-responsive gene PR1, PR2, PR3, PR8, PR14 or / and PR15 to obtain resistance; (5) Control of cotton Verticillium wilt (6) Increase cotton seedling biomass; (7) Promotes root development in cotton seedlings; (8) Increase cotton plant height, number of long roots, number of lateral roots, chlorophyll content and / or dry weight.

2. Use according to claim 1, characterized in that, The concentration of turmeric carbon dots applied is 25~100 mg / L.

3. Use according to claim 2, characterized in that, The concentration of turmeric carbon dots applied is 40-60 mg / L.

4. Use according to claim 1, 2 or 3, characterized in that, Apply as a foliar spray or soil drenching treatment during the cotton seedling stage.

5. A cotton growth stimulator and bacteriostatic agent, characterized in that, It contains 25-100 mg / L of turmeric carbon dots and agriculturally acceptable carriers.

6. A method for preventing and controlling cotton Verticillium wilt, characterized by, The carbon dots of turmeric are used as: Foliar fertilizer during seedling stage: Spray with a turmeric carbon dot solution at a concentration of 25-100 mg / L daily for 4-6 consecutive days; or Root dipping agent: Before transplanting, soak the roots of cotton seedlings in a turmeric carbon point solution with a concentration of 25~100 mg / L for 10~20 minutes.

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