New application of melatonin for preventing and treating potato dry rot and plant fungicide for preventing and treating potato dry rot

Abstract

The invention relates to new application of melatonin in prevention and treatment of potato dry rot and a plant fungicide for prevention and treatment of potato dry rot, and belongs to the technical field of potato disease prevention and treatment. In order to solve the problems that pathogenic bacteria easily generate resistance and seriously pollute the environment due to long-term use of the existing bactericide, the invention provides a new application of melatonin in prevention and treatment of potato dry rot and a plant bactericide for prevention and treatment of potato dry rot. Experiments prove that the exogenous melatonin can inhibit mycelial growth and spore germination of potato dry rot pathogenic bacteria fusarium oxysporum, and can inhibit the activity of fusarium oxysporum CAT, POD, SOD and GR to cause thallus death by destroying the cell membrane of fusarium oxysporum, so as to control the disease development of the dry rot. The fusarium oxysporum is treated by exogenous application of melatonin, growth and development of the fusarium oxysporum can be obviously inhibited, and a new way is provided for prevention and treatment of potato dry rot.

Description

Technical Field

[0001] The invention belongs to the technical field of potato disease prevention and control, and in particular relates to a new use of melatonin for preventing and controlling potato dry rot and a plant fungicide for preventing and controlling potato dry rot. Background Art

[0002] Potato dry rot is a disease caused by a variety of fungi, of which Fusarium oxysporum is one of the main pathogens. Fusarium oxysporum mainly invades potato tubers through wounds, epidermal abrasions or wounds caused by other diseases. During the infection process, the pathogen produces toxins that destroy the normal function of potato cells, causing cell death and tissue rot. At the same time, the pathogen will also grow and reproduce inside the potato tuber, producing a large number of hyphae and conidia, further aggravating the development of the disease.

[0003] Although the use of chemical agents to control potato dry rot can control the occurrence and spread of the disease to a certain extent, the long-term and large-scale use of chemical agents will cause the pathogens to develop drug resistance. Under the selection pressure of chemical agents, pathogens will gradually adapt and produce drug-resistant genes, which will gradually reduce the control effect of chemical agents. This not only increases the cost of prevention and control, but may also lead to the re-emergence of the disease. Moreover, chemical agents are easy to volatilize, lose or remain in the soil during use, causing pollution to the atmosphere, water sources and soil. These pollutants may have long-term effects on the ecosystem and destroy the ecological balance.

[0004] Biological treatment methods mainly use natural substances such as microorganisms and plant extracts to prevent and control diseases, which will not pollute the environment. This avoids the soil, water and air pollution problems that may be caused by chemical reagents, and is conducive to protecting the ecological environment and biodiversity.

[0005] Melatonin is a substance widely found in organisms in nature. Plants also contain endogenous melatonin. As a new type of plant growth regulator, it has a significant effect on plant growth and stress resistance. Melatonin can increase the adaptability of plants to adverse environments. Increasing the level of melatonin in transgenic plants through genetic engineering can further enhance the tolerance of plants to temperature stress. Therefore, the current research and application of melatonin in the field of plants mainly focuses on plant growth and development, stress resistance, etc. There has been no research or report on the application of melatonin in the prevention and control of potato dry rot. Summary of the invention

[0006] In order to solve the problem that the long-term use of existing fungicides leads to the easy development of resistance of pathogens and the serious environmental pollution, the present invention provides a new use of melatonin for preventing and controlling potato dry rot and a plant fungicide for preventing and controlling potato dry rot.

[0007] The technical solution of the present invention:

[0008] Application of melatonin in the preparation of plant fungicide for preventing and controlling potato dry rot.

[0009] Furthermore, the plant fungicide contains melatonin as the only active ingredient or one of the active ingredients.

[0010] Furthermore, the mass percentage of melatonin in the plant fungicide is 0.001 to 99%.

[0011] Furthermore, the botanical fungicide also contains auxiliary materials acceptable to the botanical fungicide.

[0012] Furthermore, the plant fungicide prevents and controls potato dry rot by inhibiting the hyphae growth of Fusarium oxysporum.

[0013] Furthermore, the plant fungicide prevents and controls potato dry rot by inhibiting the spore germination of Fusarium oxysporum.

[0014] Furthermore, the plant fungicide prevents and controls potato dry rot by damaging the cell membrane of Fusarium oxysporum.

[0015] Furthermore, the botanical fungicide prevents and controls potato dry rot by inhibiting the antioxidant system of Fusarium oxysporum.

[0016] Furthermore, when the plant fungicide is used to prevent and treat potato dry rot, the potatoes are treated with 0.01-1 mg / mL melatonin.

[0017] A plant fungicide for preventing and treating potato dry rot, wherein melatonin is used as the only active ingredient or one of the active ingredients in the plant fungicide.

[0018] Beneficial effects of the present invention:

[0019] The present invention verifies through experiments that exogenous melatonin can inhibit the hyphae growth and spore germination of Fusarium oxysporum, a pathogenic bacterium of potato dry rot, and can cause the death of the bacteria by destroying the cell membrane of Fusarium oxysporum and inhibiting the activities of CAT (catalase), POD (peroxidase), SOD (superoxide dismutase) and GR (glutathione reductase) of Fusarium oxysporum, thereby controlling the development of dry rot. The present invention treats Fusarium oxysporum by exogenous application of melatonin, which can significantly inhibit the growth and development of Fusarium oxysporum, and provides a new approach for the prevention and treatment of potato dry rot. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 These are photos of the colonies of Fusarium oxysporum in the control group and the MT treatment group in Example 1;

[0021] Figure 2This is a comparison chart of the mycelial growth inhibition rate of Fusarium oxysporum treated with different concentrations of melatonin in Example 1;

[0022] Figure 3 The scanning electron microscope images of the hyphae microscopic morphology of Fusarium oxysporum in the blank control group and the melatonin treatment group in Example 1;

[0023] Figure 4 This is a comparison of the spore germination rates of Fusarium oxysporum after being treated with different concentrations of MT for 12 hours in Example 2;

[0024] Figure 5 This is a comparison of the spore germination rates of Fusarium oxysporum treated with different concentrations of MT for 24 hours in Example 2;

[0025] Figure 6 This is a comparison of dry weight of mycelium of Fusarium oxysporum after being treated with different concentrations of MT for 7 days in Example 3;

[0026] Figure 7 This is a comparison of the MDA concentrations of the mycelial solution of Fusarium oxysporum treated with different concentrations of MT for 7 days in Example 4;

[0027] Figure 8 This is a comparison chart of CAT concentrations in mycelial solution of Fusarium oxysporum treated with different concentrations of MT for 7 days in Example 5;

[0028] Fig. 9 This is a comparison of the POD concentrations of the mycelial solution of Fusarium oxysporum treated with different concentrations of MT for 7 days in Example 5;

[0029] Fig.10 This is a comparison of SOD concentrations in mycelial solution of Fusarium oxysporum treated with different concentrations of MT for 7 days in Example 5;

[0030] Fig.11 This is a comparison chart of GR concentrations of mycelial solutions of Fusarium oxysporum treated with different concentrations of MT for 7 days in Example 5;

[0031] Fig.12 This is a comparison of the diameters of the lesions of potato slices in the inoculated group and the control group treated with melatonin at different times in Example 6;

[0032] Fig.13 The actual photographs of potato slices of the control group, the inoculated group, the control group and the drug group treated with melatonin for different time periods in Example 6;

[0033] Fig.14 This is a comparison chart of the infection volume of potato tubers in the control group, inoculated group, control group and drug group treated with melatonin at different times in Example 7;

[0034] Fig.15The photos are of the infection of potato tubers in the control group, the inoculated group, the control group and the drug group treated with melatonin at different times in Example 7;

[0035] Fig.16 These are actual photos of the infected potato tuber sections of the control group, inoculated group, control group and drug group treated with melatonin for different time periods in Example 7. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below in conjunction with the embodiments, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the protection scope of the present invention. The process equipment or devices not specifically noted in the following embodiments are all conventional equipment or devices in the art. If not specifically specified, the raw materials used in the embodiments of the present invention can be obtained commercially; if not specifically specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0037] Example 1

[0038] This example verifies the inhibitory effect of melatonin on the hyphae growth of Fusarium oxysporum.

[0039] The specific test method of this embodiment is:

[0040] Solid PDA medium was added with sterile water as the blank control group (CK-1), DMSO (dimethyl sulfoxide) was added as the solvent control group (CK-2), and MT (melatonin) was added as the treatment group (T), with MT concentration gradients of 1.5, 2.5, 5, 10 and 15 mg / mL. Then, the 6 mm diameter Fusarium oxysporum cake was inoculated on the PDA medium with the above drugs and cultured at 25 ° C in the dark. On the 7th day, the colony diameters of the two control groups and the MT treatment group were measured, and the inhibition rate was calculated.

[0041] Pure growth = average colony diameter - 6.0 mm

[0042]

[0043] Figure 1 The following are photos of the mycelium of Fusarium oxysporum in the control group and MT treatment group of this example; as shown in the figure, the mycelial growth state of Fusarium oxysporum in the sterile water blank control group (CK-1) and the DMSO solvent control group (CK-2) is consistent, indicating that DMSO has no effect on the growth of Fusarium oxysporum. Exogenous melatonin (MT) treatment can inhibit the mycelial growth of Fusarium oxysporum, and the mycelial growth inhibition rate of Fusarium oxysporum increases with the increase of treatment concentration.

[0044] Figure 2This is a comparison chart of the mycelial growth inhibition rate of Fusarium oxysporum treated with melatonin at different concentrations in this example; as shown in the figure, when the MT concentration is 1.5 mg / mL, the mycelial growth inhibition rate of Fusarium oxysporum is only 6.01%; when the concentration is 10 and 15 mg / mL, the inhibition rate is above 50%. It can be seen that there are certain differences in the inhibitory effects of different concentrations of MT on Fusarium oxysporum, among which the best inhibitory effect is achieved at 15 mg / mL.

[0045] The sample preparation method for the bacterial colony morphology scanning electron microscope in this embodiment is as follows:

[0046] Sterile water was added to the solid PDA medium as the blank control group (CK) and MT was added as the treatment group (T), and the MT concentration gradient was: 0 and 5 mg / mL.

[0047] Take some mycelia and control mycelia blocks (0.5cm×0.5cm) after 7 days of culture after MT treatment for SEM sample preparation. Fix with 2% (v / v) glutaraldehyde solution (pH 6.8) at 4℃ for 2h, wash 3 times with PBS solution, 10-15min each time. Soak in 1% (v / v) osmium acid solution at 4℃ for 2h. Dehydrate with 50% (v / v), 70% (v / v), 95% (v / v), and 100% (v / v) ethanol solutions at 4℃ for 10min respectively, and replace with isoamyl acetate for 20min. The dehydrated samples are critical point dried and vacuum gold plated. The prepared SEM samples are observed and photographed with a Hitachi S-3400N scanning electron microscope.

[0048] Figure 3 This is a scanning electron microscope image of the mycelium micromorphology of Fusarium oxysporum in the blank control group and the melatonin treatment group of this embodiment; as shown in the figure, the mycelium of the control group grew smoothly, evenly and densely, and the thickness was consistent; after being treated with 5 mg / mL of MT, the mycelium morphology of Fusarium oxysporum changed significantly, a large number of mycelium twisted and entangled together, the thickness was inconsistent, the mycelium became sparse, a large number of mycelium grew sparsely, tightly entangled together, and broke, shrunken and collapsed, which restricted the growth of mycelium. It can be seen that after MT was used to treat mycelium, the mycelium morphology was greatly damaged and the degree of damage was obvious, which made it unable to perform normal physiological functions and eventually led to death.

[0049] Example 2

[0050] This example verifies the inhibitory effect of melatonin on the germination of Fusarium oxysporum spores.

[0051] The specific test method of this embodiment is:

[0052] Take out the plate of Fusarium oxysporum cultured at 25℃ for 7 days, add a small amount of sterile water, gently scrape off the pathogen spores on the plate, then transfer it to a sterilized conical flask, shake, filter, and finally dilute the spore concentration to 1×10 8 Pieces / mL.

[0053] Spores were treated with 10, 5 and 0.5 mg / mL MT solutions, respectively. The spore suspension was added to a glass slide, a concave cover slip was added, and the slide was sealed with sterile water to keep it moist. No MT solution was added as a control. The spores were cultured at 25°C, and the number of spore germination was recorded under a microscope after 12 and 24 hours. 100 spores were examined each time.

[0054] Spore germination rate (%) = number of spore germination / total number of spores investigated × 100%

[0055] Figure 4 and Figure 5 They are respectively the comparison diagrams of spore germination rate of Fusarium oxysporum treated with different concentrations of MT in this embodiment for 12h and 24h; as shown in the figure, spore germination of Fusarium oxysporum spores was inhibited after treatment with different concentrations of MT solution, and the spore germination rate was significantly lower than that of the blank control PD treatment without MT. After 12h of treatment, 10mg / mL had the lowest inhibition of spore germination rate, reaching 7.31%. As the concentration of MT decreased, the germination rate also gradually increased. After 24h of treatment, the spore germination rate of 10mg / mL was still the lowest, only 9.74%, but it was improved compared with the treatment of 12h. Similar to the results after 12h of treatment, the germination rate also gradually increased as the concentration of MT decreased. The overall spore germination rate increased after 24h of treatment compared with 12h.

[0056] Example 3

[0057] This example verifies the inhibitory effect of melatonin on the dry weight of Fusarium oxysporum hyphae.

[0058] The specific test method of this embodiment is:

[0059] Potato dextrose liquid medium (PD) containing 10, 5 and 0.5 mg / mL MT solution was prepared, and no MT was used as a control. Each bottle contained 50 mL of medium, inoculated with a bacterial cake (Ф=8 mm) of Fusarium oxysporum cultured in PDA for 7 days, and cultured at 25°C and 100 rpm for 7 days, filtered the mycelium, and measured the dry weight of the mycelium after drying, with 3 bottles for each treatment and 3 replicates.

[0060] Figure 6This is a comparison of the dry weight of mycelium after 7 days of treatment of Fusarium oxysporum with different concentrations of MT in this embodiment; as shown in the figure, exogenous MT treatment can inhibit the growth of Fusarium oxysporum mycelium, and the dry weight of mycelium continues to decrease with the increase of treatment concentration, and is significantly lower than the blank control. When the MT concentration is 10 mg / mL, the dry weight of mycelium after 7 days of culture is 22% of the control; at 5 mg / mL, the dry weight is 33% of the control; at 0.5 mg / mL, it is only 50.66% of the control. The dry weight of mycelium treated with different MT concentrations is significantly different. As the treatment concentration increases, the dry weight of mycelium decreases more significantly.

[0061] Example 4

[0062] This example verifies the destructive effect of melatonin on the cell membrane of Fusarium oxysporum.

[0063] The specific test method of this embodiment is:

[0064] Sterile water was added to the solid PDA medium as a blank control group (CK-1), DMSO was added as a solvent control group (CK-2), and MT was added as a treatment group (T), and the MT concentration gradient was 5 and 1 mg / mL. Then, a 6 mm diameter Fusarium cake was inoculated on the PDA medium with the above drugs, and 0.1 g of mycelium after MT treatment and control mycelium after 7 days of culture were taken, wrapped with tin foil, quickly frozen in liquid nitrogen, and stored in a -80 ° C refrigerator for testing.

[0065] MDA is the main metabolite of bacterial membrane lipid peroxidation and an important indicator for measuring cell membrane damage.

[0066] Figure 7 This is a comparison of the MDA concentration of the mycelial solution of Fusarium oxysporum after 7 days of treatment with different concentrations of MT in this embodiment; as shown in the figure, compared with the control, as the MDA concentration of the 1 and 5 mg / mL MT treatment groups increased, the MDA concentration of the mycelial solution of Fusarium oxysporum increased, increasing by 1.15 and 1.64 times, respectively. The results show that MT treatment causes membrane lipid peroxidation in the bacteria, increases the MDA content of the bacteria, and causes damage to the cell membrane.

[0067] Example 5

[0068] This example verifies the inhibitory effect of melatonin on the antioxidant system of Fusarium oxysporum.

[0069] The specific test method of this embodiment is:

[0070] Sterile water was added to the solid PDA medium as a blank control group (CK-1), DMSO was added as a solvent control group (CK-2), and MT was added as a treatment group (T), and the MT concentration gradient was 5 and 1 mg / mL. Then, a 6 mm diameter Fusarium cake was inoculated on the PDA medium with the above drugs, and 0.1 g of mycelium after MT treatment and control mycelium after 7 days of culture were taken, wrapped with tin foil, quickly frozen in liquid nitrogen, and stored in a -80 ° C refrigerator for testing.

[0071] CAT exists in the peroxisome of cells and is a marker enzyme of peroxisome. Its main function is to catalyze the decomposition of hydrogen peroxide into oxygen and water. Figure 8 This is a comparison of the CAT concentration of the mycelial solution after 7 days of treatment of Fusarium oxysporum with different concentrations of MT in this example; as shown in the figure, after treatment with 1 and 5 mg / mL of MT, the CAT of the mycelial solution decreased as the concentration increased, but the reduction effect was not significant. The results show that MT has an inhibitory effect on the CAT activity of the bacteria, and the difference between different concentrations is not significant.

[0072] POD can catalyze many reactions and catalyze substrate oxidation using hydrogen peroxide as an electron acceptor. It mainly exists in the peroxisome of the carrier and has the dual function of eliminating the toxicity of hydrogen peroxide and phenols, amines and aldehydes. Fig. 9 This is a comparison of the POD concentration of the mycelial solution of Fusarium oxysporum after 7 days of treatment with different concentrations of MT in this example; as shown in the figure, 1 and 5 mg / mL of MT treatment will reduce the POD activity of the bacteria, and as the MT concentration increases, the POD activity decreases more. The results show that MT has an inhibitory effect on the POD activity of the bacteria, and the difference between different concentrations is significant.

[0073] SOD is a mitochondrial protein that can remove O2 - The main antioxidant enzymes Fig.10 This is a comparison of the SOD concentration of the mycelial solution of Fusarium oxysporum after 7 days of treatment with different concentrations of MT in this example; as shown in the figure, after treatment with 1 and 5 mg / mL of MT, the SOD activity of the bacteria decreased by 22.47% and 33.88% respectively compared with the control group. The above results show that MT has an inhibitory effect on bacterial SOD, and the inhibitory effect gradually increases with the increase of concentration.

[0074] GR is a flavoprotein oxidoreductase widely found in eukaryotic and prokaryotic organisms and is a key enzyme in the glutathione redox cycle. GR helps maintain the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in the body and plays a key role in the removal of reactive oxygen species in oxidative stress reactions. Fig.11This is a comparison of the GR concentration of the mycelial solution of Fusarium oxysporum after 7 days of treatment with different concentrations of MT in this example; as shown in the figure, after treatment with 1 and 5 mg / mL of MT, the GR activity of the bacteria decreased by 45.39% and 33.47% respectively compared with the control group. The results show that MT has an inhibitory effect on the GR activity of the bacteria, and the difference between different concentrations is significant.

[0075] Example 6

[0076] This example verifies the preventive and therapeutic effect of melatonin on potato slice dry rot.

[0077] The specific test method of this embodiment is:

[0078] Take healthy potato Eugene tubers with consistent appearance, no damage, wash with clean water, disinfect with 5% sodium hypochlorite for 2 minutes, rinse with sterile water 3 times, and put them in a sterile clean bench to dry naturally in the shade. Cut the tubers into thin slices with a thickness of about 0.5 cm in the sterile clean bench, wash the slices with sterile water, wipe with 75% alcohol, burn off the residual alcohol on the flame of an alcohol lamp, and put them in a culture dish covered with sterile filter paper for use.

[0079] The treatments were divided into four groups:

[0080] ① Control group (CK), i.e., non-induced and non-inoculated group, sterile water was added into the central circular groove of potato chips until the water was absorbed by the tubers, and then the lid of the culture dish was closed.

[0081] ② Inoculation group (Fo), a piece of Fusarium oxysporum cake (diameter = 4 mm) cultured on PDA for 7 days was placed in the circular groove in the center of the potato chip, and then the lid of the culture dish was covered.

[0082] ③ For the control group (MT1-Fo, MT2-Fo, MT3-Fo), the potato chips were soaked in melatonin solutions of different concentrations for 20 minutes and placed in a petri dish covered with sterile filter paper for later use. After the drug was absorbed by the slices, a piece of Fusarium oxysporum cake cultured on PDA for 7 days was placed in the circular groove in the center of the potato chip, and finally the lid of the petri dish was covered.

[0083] The melatonin concentrations in the different treatment and treatment groups were MT1-Fo: 1 mg / mL, MT2-Fo: 0.1 mg / mL, and MT3-Fo: 0.01 mg / mL.

[0084] ④ Drug groups (MT1, MT2, MT3): soak potato chips in melatonin solutions of different concentrations for 20 min. After the drug was absorbed by the slices, the lid of the culture dish was closed without inoculating Fusarium oxysporum.

[0085] After treatment, the chips were cultured in an incubator at 25°C and a humidity of 85-90% (moisture retention for 24 hours). The diameter of the lesions was measured by the cross method on days 0, 3 and 6, respectively. Fifteen chips were treated with each concentration and repeated three times.

[0086] Fig.12 This is a comparison diagram of the diameter of the lesions of potato slices in the inoculated group and the control group treated with melatonin at different times in this example; Fig.13 The following are photos of potato slices in the control group, inoculated group, control group and drug group treated with melatonin at different times in this embodiment; as shown in the figure, the rotten area of ​​the pathogen in the inoculated group began to increase on the 3rd day of treatment, and the slice area was significantly larger than that of the control group on the 6th day of inoculation. There was no significant difference in the infection area after the three concentrations of melatonin in the control group were treated and inoculated with pathogens, indicating that the control effects of melatonin treatment concentrations of 1 mg / mL, 0.1 mg / mL and 0.01 mg / mL were similar, so 0.01 mg / mL can be selected in actual production to treat potato slices and prevent and treat potato dry rot.

[0087] Example 7

[0088] This example verifies the preventive and therapeutic effect of melatonin on potato tuber dry rot.

[0089] The specific test method of this embodiment is:

[0090] Take healthy Eugene potato tubers that are neat in appearance and undamaged, rinse them with clean water, disinfect their surfaces with 5% sodium hypochlorite for 1 min, rinse them with sterile water 3 times, dry them naturally, place them in a sterile clean bench, and use a hole puncher to punch small holes with a depth of 3 mm and a diameter of 8 mm on the surface of the tubers for later use.

[0091] The treatments were divided into four groups:

[0092] ① Control group (CK), 100 μL of sterile water was added to the small holes on the tubers until the water was absorbed by the tubers, then the original potato tuber tissue was stuffed back and sealed with transparent tape.

[0093] ② Inoculation group (Fo), a piece of Fusarium oxysporum cake (Ф=8 mm) cultured on PDA for 7 days was placed right into the small hole of the potato, and then the original potato tuber tissue was stuffed back and sealed with transparent tape.

[0094] ③ Prevention and treatment group (MT-Fo), i.e., 100 μL of 10 mg / mL melatonin was added into the small hole of potato. After the drug was absorbed by the tuber, a piece of Fusarium oxysporum cake (Ф=8 mm) cultured on PDA for 7 days was placed in the small hole of potato. Finally, the original potato tuber tissue was stuffed back and sealed with transparent tape.

[0095] ④ Drug group (MT), i.e., 100 μL of 10 mg / mL melatonin was added into the small holes of potatoes. After the drug was absorbed by the tubers, the original potato tuber tissue was stuffed back and sealed with transparent tape. No Fusarium oxysporum was inoculated.

[0096] After the treatment, the potatoes were cultured in an incubator at 25°C and humidity of 85-90% (moisturizing for 24 hours). Three potatoes were randomly cut open on the 0th, 4th, 8th and 16th days to observe their internal and external morphology. The appearance of the potato tubers at different infection times and the changes in morphological structure after infection were observed and recorded and analyzed. On the 16th day, the potatoes were cut open to measure the diameter of the lesions. The infection volume was calculated, and each treatment was repeated 3 times.

[0097]

[0098] Fig.14 , Fig.15 and Fig.16 The figures are respectively a comparison of the infection volume of potato tubers of the control group, the inoculated group, the control group and the drug group treated with melatonin at different times in Example 7, actual photos of the infection of potato tubers and actual photos of the infection of the cross-section of potato tubers; as shown in the figure, the rot volume of the pathogen in the inoculated group began to increase significantly on the 4th day of treatment, and on the 8th day of inoculation, obvious depressions and rot appeared on the inoculated and non-inoculated parts of the tuber surface, white hyphae began to appear at the inoculated part, and the potato flesh shrank and browned.

[0099] After melatonin treatment, the tubers in the control group inoculated with pathogens began to show lesion symptoms on the 8th day of treatment. There was no obvious depression at the inoculation site, but trace amounts of hyphae were visible. On the 16th day of inoculation, the potato flesh at the junction of the diseased and healthy tubers turned brown, but did not expand further, and the lesion diameter did not change significantly, indicating that melatonin had a certain effect on preventing the occurrence of dry rot in the inoculated tubers and could reduce the infection of Fusarium on the tubers. The morphological changes of the tubers in the blank control group and the drug group were basically similar, with no symptoms such as lesions, necrosis or rot, indicating that melatonin itself had no effect on the commercial quality of the tubers.

[0100] In summary, it can be seen that melatonin, as a control agent for potato dry rot, can reduce the infection of Fusarium after treating potato tubers in advance, and has a certain control effect on potato dry rot.

Claims

1. Application of melatonin in the preparation of plant fungicides for preventing and controlling potato dry rot.

2. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: The plant fungicide uses melatonin as the only active ingredient or one of the active ingredients.

3. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: The mass percentage of melatonin in the plant fungicide is 0.001-99%.

4. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: The botanical fungicide also contains auxiliary materials acceptable to the botanical fungicide.

5. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: The plant fungicide prevents and controls potato dry rot by inhibiting the hyphae growth of Fusarium oxysporum.

6. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: The plant fungicide prevents and controls potato dry rot by inhibiting the spore germination of Fusarium oxysporum.

7. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: The botanical fungicide controls potato dry rot by damaging the cell membrane of Fusarium oxysporum.

8. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: The botanical fungicide prevents and controls potato dry rot by inhibiting the antioxidant system of Fusarium oxysporum.

9. The use of melatonin in the preparation of a fungicide for preventing and treating potato dry rot according to claim 1, characterized in that: When the plant fungicide is used to prevent and treat potato dry rot, the potato is treated with 0.01-1 mg / mL melatonin.

10. A plant fungicide for preventing and treating potato dry rot, characterized in that: The plant fungicide uses melatonin as the only active ingredient or one of the active ingredients.

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