Method for reducing morbidity of watermelons under high-humidity-heat condition

Abstract

The invention discloses a method for reducing the morbidity of watermelons under the high-humidity-heat condition, and belongs to the technical field of watermelon cultivation and planting. Before watermelons are planted, a base fertilizer is applied, and meanwhile, a composite soil conditioner is used for improving soil; seeds are coated before watermelon sowing, and then the seeds are sown in the improved soil; the composite soil conditioner is prepared from the following components in parts by mass: 100 parts of calcined diatomite, 10-15 parts of perlite, 10-13 parts of bentonite, 8-10 parts of biomass charcoal, 5-8 parts of dried coco coir, 20-30 parts of decomposed organic matters and 5-8 parts of a composite microbial agent. According to the method, coating of the watermelon seeds and application of the soil conditioner in the soil are carried out at the same time, adverse effects caused by high-humidity and heat conditions in the watermelon growth process are effectively improved, the morbidity is reduced, and therefore the yield of watermelons is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of watermelon cultivation and planting, and particularly relates to a method for reducing the incidence of watermelon under high humidity and heat conditions. Background Art

[0002] Watermelon has a wide adaptability to soil, so it is widely planted in various parts of my country. my country is a major consumer of watermelons. The natural maturity period of watermelons is in summer. As the area south of the Yangtze River enters the plum rain season in summer, the soil moisture increases greatly. Watermelon is prone to increased incidence under high humidity and heat conditions. The main reasons are as follows: 1. The pathogens of diseases such as watermelon blight like high temperature and humidity. Under high temperature and humidity conditions, the reproduction speed is accelerated and the number of bacteria increases rapidly; 2. Pathogens can be spread through rainwater, irrigation water and soil, so humid and hot conditions provide favorable conditions for the growth and spread of pathogens. 3. The humid and hot environment will have a certain impact on the physiological functions of watermelon plants, such as weakened photosynthesis and enhanced respiration, resulting in reduced stress resistance of watermelon, further increasing the risk of infection; 4. The soil humidity is too high, and the root respiration of the plant is inhibited, affecting the absorption and utilization of soil nutrients.

[0003] Therefore, how to reduce the incidence of watermelon under hot and humid conditions is an effective means to ensure watermelon production. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for reducing the incidence of watermelon under high humidity and heat conditions. By simultaneously coating watermelon seeds and applying soil conditioners to the soil, the adverse effects of high humidity and heat conditions during the growth of watermelon are effectively improved, the incidence rate is reduced, and the watermelon yield is ensured.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for reducing the incidence of watermelon under high humidity and heat conditions. Before planting watermelon, base fertilizer is applied and a composite soil conditioner is used to improve the soil; before sowing watermelon, the seeds are coated and then sown in the improved soil;

[0007] The composite soil conditioner comprises the following components in parts by mass: 100 parts of calcined diatomaceous earth, 10-15 parts of perlite, 10-13 parts of bentonite, 8-10 parts of biochar, 5-8 parts of dried coconut bran, 20-30 parts of decomposed organic matter and 5-8 parts of composite microbial agent.

[0008] The term "calcined diatomaceous earth" refers to diatomaceous earth prepared by high-temperature calcination. "Dried coconut husk" refers to coconut husk dried at high temperature. "Biomass charcoal" is obtained by high-temperature pyrolysis of biomass materials, including but not limited to various plant straws, such as corn straw, wheat straw, rice husk, grass straw or leaves.

[0009] Diatomite is a porous siliceous biological sedimentary rock formed by the remains of diatomite. After calcination, the pores formed inside it increase and enlarge, and the specific surface area is greatly improved, which can greatly improve the air permeability of the soil; bentonite has a porous structure, and it can expand after absorbing water, making the soil structure loose, improving the permeability of the soil, and at the same time, it has a high cation exchange capacity, which can absorb and retain nutrients in the soil and reduce nutrient loss; perlite has tiny pores inside, and the particle shape of perlite makes the pores between it and the soil particles also increase accordingly. These pores and pores can quickly discharge water from the soil and reduce water retention. The three components of calcined diatomite, perlite and bentonite can be combined in a specific proportion to greatly improve the air permeability of the soil, which is beneficial to improve the adverse effects of high-humidity soil on the root system of watermelon. Biochar and dried coconut bran can increase the organic matter content of the soil. The increase in organic matter content and the porosity of biochar and coconut bran also further improve the texture of the soil. The combination of the three can further optimize the soil environment. The composite microbial agent can be adsorbed inside the porous components and inhibit the growth and reproduction of pathogens through competition, antagonism and induced resistance, thereby improving the disease resistance of watermelon.

[0010] The method for coating the seeds is as follows: mixing nano white zeolite and trace elements and dissolving them in an aqueous solution of sodium alginate, chitosan and ethylene glycol, adding watermelon seeds, mixing well, taking them out and air-drying them; the mass ratio of the nano white zeolite to the trace elements is 10:(3-5).

[0011] The macroporous structure of nano white zeolite can absorb trace elements, so that the trace elements can provide sufficient nutrients for watermelon seeds in the early stage. Sodium alginate and chitosan are mixed in specific components with ethylene glycol as coating agents for watermelon seeds. Ammonium alginate and chitosan are natural polymer materials with good biocompatibility and degradability, which can provide a suitable environment for seed germination. The addition of ethylene glycol can also adjust permeability and moisture retention, promote seed germination, and at the same time, the three components have good antibacterial properties after mixing, which effectively avoids the ability of watermelon seeds to resist pathogens.

[0012] Preferably, the high-humidity soil in the southern region is usually acidic, which is not conducive to the growth of watermelon. Therefore, the composite soil conditioner of the present invention also includes a pH regulator, which is limestone powder. The amount of the pH regulator added is based on adjusting the soil pH value to 6.0-7.

[0013] Preferably, the mass concentrations of the sodium alginate, chitosan and ethylene glycol in the aqueous solution are 1-2%, 1-2% and 5-6%, respectively.

[0014] Preferably, the total amount of the nano white zeolite and trace elements added to the aqueous solution is 8-10 wt.%.

[0015] Preferably, the method for preparing the calcined diatomite is to calcine the diatomite at 500-600° C. for 1-2 hours.

[0016] Preferably, the base fertilizer is decomposed organic matter; the decomposed organic matter is prepared by mixing animal manure and plant straw in a mass ratio of (2-3):10, decomposing for 1-2 weeks, and then drying and crushing to 10-20 meshes.

[0017] Preferably, the trace elements are copper, iron, manganese, zinc, boron and molybdenum. The proportion of the trace elements can be prepared according to the conventional proportion of trace elements required for watermelon.

[0018] Preferably, the composite microbial agent includes Bacillus subtilis, Trichoderma viride, actinomycetes and Trichoderma harzianum; the content of each fungus is ≥ 1 billion / g.

[0019] Preferably, the mass ratio of the base fertilizer to the composite soil conditioner is 100:(4-6).

[0020] Bacillus subtilis directly destroys the mycelial structure of pathogens by producing antimicrobial substances such as lipopeptide antibiotics, thereby inhibiting the growth and reproduction of pathogens. For watermelon wilt, Bacillus subtilis can significantly reduce the number of pathogens such as Fusarium oxysporum around the watermelon root system, reducing the probability of wilt. Trichoderma viride can produce a variety of antimicrobial substances, which have a significant inhibitory effect on pathogens such as watermelon wilt. Trichoderma viride can invade pathogen colonies and inhibit their growth and reproduction. Through this mechanism, the number of pathogens around the watermelon root system is effectively reduced, thereby reducing the probability of disease. Actinomycetes can produce a variety of antimicrobial substances, which have a significant inhibitory effect on pathogens such as watermelon wilt. By producing antimicrobial active substances such as antibiotics and cell wall degrading enzymes, actinomycetes can destroy the cell wall and cell membrane of pathogens, inhibit their growth and reproduction, and thus reduce the occurrence of watermelon diseases. Trichoderma harzianum can induce systemic resistance in watermelon plants, and this resistance mechanism can fully activate the watermelon's own defense system. When watermelon plants are attacked by pathogens, systemic resistance can respond quickly and produce a series of defense-related proteins and enzymes, such as chitinase, β-1,3-glucanase, etc. These substances can decompose the cell walls of pathogens, thereby effectively inhibiting the growth and reproduction of pathogens.

[0021] In a second aspect, the present invention also provides a method for planting watermelons under high humidity and heat climates, wherein the method for reducing the incidence of watermelons under high humidity and heat conditions is used to reduce the incidence of watermelons in the early stage, and conventional water and fertilizer management is performed in the later stage. In high humidity and heat regions, the amount of rainfall is large, and the number of irrigation times can be reduced according to soil conditions. Since the soil conditioner includes organic fertilizers and the improved soil reduces nutrient loss, the amount of inorganic fertilizer applied is reduced by 20% to 40% according to the conventional amount.

[0022] The present invention has the following technical effects:

[0023] The present invention coats watermelon seeds with a seed coating agent, which not only provides early nutrients but also improves antibacterial properties, thereby greatly improving the germination rate of watermelon seeds; at the same time, by improving the soil before sowing, the soil organic matter content is increased and the soil structure is effectively improved. The addition of the composite microbial agent directly improves the disease resistance of watermelon during its growth process. The present invention uses a multi-pronged approach and synergistic methods to reduce the incidence of watermelon in high-temperature and high-humidity soils, thereby ensuring the yield of watermelon.

[0024] The method of the present invention is aimed at the cultivation and planting of watermelons under high humidity and heat conditions. The method of the present invention can reduce the amount of fertilizer applied to the watermelons, thereby ensuring the yield and greatly saving the cost. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] The embodiment of the present invention discloses a method for reducing the incidence of watermelon under high humidity and heat conditions. Before planting watermelon, base fertilizer is applied and a composite soil conditioner is used to improve the soil; before sowing watermelon, the seeds are coated and then sown in the improved soil;

[0031] The composite soil conditioner comprises the following components by weight: 100 parts of calcined diatomaceous earth, 10-15 parts of perlite, 10-13 parts of bentonite, 8-10 parts of biochar, 5-8 parts of dried coconut bran and 5-8 parts of composite microbial agent.

[0032] The method for coating the seeds is as follows: mixing nano white zeolite and trace elements and dissolving them in an aqueous solution of sodium alginate, chitosan and ethylene glycol, adding watermelon seeds, mixing well, taking them out and air-drying them; the mass ratio of the nano white zeolite to the trace elements is 10:(3-5).

[0033] The preparation method of the composite soil conditioner may be simple physical blending in some embodiments. In other embodiments, the calcined diatomaceous earth, perlite and bentonite may be blended and then granulated, and then blended with other components. The granulation method is not limited and conventional technical means may be used.

[0034] The high humidity soil in the southern region is usually acidic, which is not conducive to the growth of watermelon. Therefore, in some preferred embodiments of the present invention, the composite soil conditioner also includes a pH regulator, which is limestone powder, and the amount of the pH regulator added is such that the soil pH value is adjusted to 6.0 to 7. If it is a coastal area, the soil is alkaline, and humic acid can also be used to adjust the pH value to 6.0 to 7.

[0035] Preferably, the mass concentrations of the sodium alginate, chitosan and ethylene glycol in the aqueous solution are 1-2%, 1-2% and 5-6%, respectively.

[0036] Preferably, the total amount of the nano white zeolite and trace elements added to the aqueous solution is 8-10 wt.%.

[0037] Preferably, the method for preparing the calcined diatomite is to calcine the diatomite at 500-600° C. for 1-2 hours.

[0038] Preferably, the base fertilizer is decomposed organic matter; the decomposed organic matter is prepared by mixing animal manure and plant straw in a mass ratio of (2-3):10, decomposing for 1-2 weeks, and then drying and crushing to 10-20 meshes.

[0039] Preferably, the trace elements are copper, iron, manganese, zinc, boron and molybdenum. The proportion of the trace elements can be prepared according to the conventional proportion of trace elements required for watermelon. You can prepare it yourself or directly buy a product containing composite trace elements.

[0040] Preferably, the composite microbial agent includes Bacillus subtilis, Trichoderma viride, actinomycetes and Trichoderma harzianum; the content of each fungus is ≥ 100 million fungi / g.

[0041] In some preferred embodiments, the mass ratio of the base fertilizer to the composite soil conditioner is 100:(4-86).

[0042] The embodiment of the present invention also discloses a method for planting watermelons under high humidity and heat climates. In the early stage, the method for reducing the incidence of watermelons under high humidity and heat conditions is used to reduce the incidence of watermelons, and in the later stage, conventional water and fertilizer management is performed. In high humidity and heat areas, the amount of rain is large, and the number of irrigation times can be reduced according to soil conditions. Since the soil conditioner includes organic fertilizers and the improved soil reduces nutrient loss, the amount of inorganic fertilizer applied is reduced by 20% to 40% with reference to the conventional amount.

[0043] In the embodiments of the present invention, “parts” refer to “parts by mass” unless otherwise specified.

[0044] In the following examples, the biomass charcoal is corn straw biomass charcoal; the decomposed organic matter is prepared by mixing chicken manure, cow dung, rice bran and corn straw in equal quantities, decomposing for 2 weeks, and then drying and crushing.

[0045] Among the composite microorganisms, Bacillus subtilis was purchased from Jinan Jinyuan Biotechnology Co., Ltd., 100 billion / g;

[0046] Trichoderma viride was purchased from Shandong Nuojie Biotechnology Co., Ltd., 10 billion / g;

[0047] Actinomycetes were purchased from Shandong Zhongkangyuan Biotechnology Co., Ltd., 10 billion / g;

[0048] Trichoderma harzianum was purchased from Shandong Dehe Mingxing Biotechnology Co., Ltd., with a purchase weight of ≥ 100 million fungi / g.

[0049] The composite microbial agent is prepared by mixing the above four microbial agents in equal quantities.

[0050] Trace elements including copper, iron, manganese, zinc, boron and molybdenum were purchased from the composite trace elements of Zhengzhou Zhengyan Biotechnology Co., Ltd.

[0051] Preparation method of calcined diatomite: calcine the diatomite at 600°C for 1.5h, and then grind it through a 50-mesh sieve after cooling.

[0052] In the following embodiments, the planting area was selected from a suburb of Shanghai, the soil acidity was slightly acidic, pH value was 5.5, limestone powder was first sprinkled on the planting area, and then mixed with the soil after deep plowing in the later stage, and the amount of limestone powder applied was based on the soil pH reaching 6-7.

[0053] Example 1

[0054] A method for reducing the incidence of watermelon under high humidity and heat conditions, comprising the following steps:

[0055] S1. Sodium alginate, chitosan and ethylene glycol are dissolved in water, and the concentrations (mass concentration, the same below) in the aqueous solution are 2%, 1.5% and 5.5%, respectively;

[0056] S2. Nano white zeolite and trace elements are weighed in a mass ratio of 10:3, mixed and dissolved in the aqueous solution, wherein the total amount of nano white zeolite and trace elements added to the aqueous solution is 10wt.%, watermelon seeds are added, soaked for 30min, and then removed and air-dried for standby use;

[0057] S3. Prepare a composite soil conditioner according to the following weight proportions: 100 parts of calcined diatomaceous earth, 10 parts of perlite, 10 parts of bentonite, 8 parts of biochar, 8 parts of dried coconut bran and 5 parts of composite microbial agent.

[0058] S4. Deeply plow the soil (more than 30 cm), apply the decomposed organic matter and the composite soil conditioner to the soil by broadcasting, with the application amount of decomposed organic matter being 1500 kg / mu and the application amount of the composite soil conditioner being 75 kg / mu;

[0059] S5. Planting watermelon seeds;

[0060] S6. Topdressing: When the watermelon seedlings grow to 2-3 true leaves, apply urea at 2kg / mu; after the watermelon vines are extended, apply nitrogen, phosphorus and potassium compound fertilizer at 5kg / mu; when the young watermelon fruits grow to the size of eggs, apply melon-swelling fertilizer (commercially available nitric-sulfur-based compound fertilizer) at 10kg / mu. During this period, carry out routine daily management (do not use chemical methods to prevent and control diseases).

[0061] Example 2

[0062] A method for reducing the incidence of watermelon under high humidity and heat conditions, comprising the following steps:

[0063] S1. Same as Example 1;

[0064] S2. Nano white zeolite and trace elements are weighed in a mass ratio of 10:5, mixed and dissolved in the aqueous solution, wherein the total amount of nano white zeolite and trace elements added to the aqueous solution is 10wt.%;

[0065] S3~S6. Same as Example 1.

[0066] Example 3

[0067] A method for reducing the incidence of watermelon under high humidity and heat conditions, comprising the following steps:

[0068] S1. Same as Example 1;

[0069] S2. Nano white zeolite and trace elements are weighed in a mass ratio of 10:4, mixed and dissolved in the aqueous solution, wherein the total amount of nano white zeolite and trace elements added to the aqueous solution is 10wt.%;

[0070] S3~S6. Same as Example 1.

[0071] Example 4

[0072] A method for reducing the incidence of watermelon under high humidity and heat conditions, comprising the following steps:

[0073] S1-S2. Same as Example 1;

[0074] S3. Prepare a composite soil conditioner according to the following weight proportions: 100 parts of calcined diatomaceous earth, 15 parts of perlite, 13 parts of bentonite, 9 parts of biochar, 5 parts of dried coconut bran and 8 parts of composite microbial agent.

[0075] S4~S6. Same as Example 1.

[0076] Example 5

[0077] A method for reducing the incidence of watermelon under high humidity and heat conditions, comprising the following steps:

[0078] S1-S2. Same as Example 1;

[0079] S3. Prepare a composite soil conditioner according to the following weight proportions: 100 parts of calcined diatomaceous earth, 12 parts of perlite, 10 parts of bentonite, 10 parts of biochar, 8 parts of dried coconut bran and 6 parts of composite microbial agent.

[0080] S4~S6. Same as Example 1.

[0081] Example 6

[0082] A method for reducing the incidence of watermelon under high humidity and heat conditions, which is the same as Example 1, except that step S4: the application amount of the composite soil conditioner is 60 kg / mu.

[0083] Example 7

[0084] A method for reducing the incidence of watermelon under high humidity and heat conditions, which is the same as Example 1, except that step S4: applying a composite soil conditioner at an amount of 90 kg / mu.

[0085] Comparative Example 1

[0086] Same as Example 1, except that equal amounts of perlite and bentonite are replaced with calcined diatomaceous earth.

[0087] Comparative Example 2

[0088] Same as Example 1, except that bentonite is replaced by perlite.

[0089] Comparative Example 3

[0090] Same as Example 1, except that calcined diatomaceous earth is replaced by diatomaceous earth.

[0091] Comparative Example 4

[0092] Same as Example 1, except that the calcined diatomaceous earth, perlite and bentonite are replaced by fine river sand.

[0093] Comparative Example 5

[0094] The same as Example 1, except that the mass of dry coconut bran and biochar is replaced by decomposed organic matter.

[0095] Comparative Example 6

[0096] The same as Example 1, the only difference is that the addition of nano white zeolite is omitted when coating the watermelon seeds.

[0097] Comparative Example 7

[0098] Same as Example 1, except that the watermelon seeds are not coated.

[0099] Watermelon planting was carried out using the methods of Examples 1-6 and Comparative Examples 1-7. The planting experimental area was selected from a suburb of Shanghai. The area entered the plum rain season in mid-June, and the precipitation during the entire plum rain season was 338.0 mm. The planting experimental area was divided into 15 small plots, each with a size of 667 m 2 , randomly adopt the methods of the above-mentioned Examples 1-7 and Comparative Examples 1-7 to plant watermelons, and set up a blank control (based on Example 1, the composite soil conditioner is omitted). The watermelon planting variety is Qilin, the cultivation method is open-air cultivation, the sowing time is mid-April 2023, the harvest time is early to mid-July, and the planting density is 700 plants / mu. The growth and harvest of watermelons in each plot are statistically analyzed, and the results are shown in Table 1.

[0100] Table 1 Statistics of watermelon incidence and yield results

[0101]

[0102]

[0103] Note: The calculation method of incidence rate is: number of diseased plants / 700×100%; the number of diseased plants refers to the number of plants infected with various pathogens and suffering from diseases.

[0104] As can be seen from Table 1, compared with the blank control group, the planting methods of Examples 1-7 can achieve an increase in yield by reducing the incidence of watermelon plants, especially in Example 7, the incidence is only 2%, the yield per mu reaches 3718kg / mu, and the single fruit weight is greater than 7 jin. Comparative Examples 1-3 changed the ratio of calcined diatomaceous earth, bentonite and perlite, which slightly increased the incidence and affected the yield. Comparative Example 4 directly replaced it with fine river sand, which greatly increased the incidence of watermelon, and both the single fruit weight and the yield per mu decreased significantly. Comparative Examples 6 and 7 changed the coating treatment method for watermelon seeds, which significantly reduced the incidence of watermelon plants, and the yield and single fruit weight also decreased significantly.

[0105] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for reducing the incidence of watermelon under high humidity and heat conditions, characterized in that: Before planting watermelons, apply base fertilizer and use compound soil conditioner to improve the soil; before sowing watermelons, coat the seeds and then sow them in the improved soil; The composite soil conditioner comprises the following components by weight: 100 parts of calcined diatomite, 10-15 parts of perlite, 10-13 parts of bentonite, 8-10 parts of biochar, 5-8 parts of dried coconut bran and 5-8 parts of composite microbial agent; The method for coating the seeds is as follows: mixing nano white zeolite and trace elements and dissolving them in an aqueous solution of sodium alginate, chitosan and ethylene glycol, adding watermelon seeds, mixing well, taking them out and air-drying them; the mass ratio of the nano white zeolite to the trace elements is 10:(3-5).

2. The method for reducing the incidence of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The composite soil conditioner also includes a pH regulator, which is limestone powder. The amount of the pH regulator added is such that the soil pH value is adjusted to 6.0-7.

3. The method for reducing the incidence of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The mass concentrations of the sodium alginate, chitosan and ethylene glycol in the aqueous solution are 1-2%, 1-2% and 5-6% respectively.

4. The method for reducing the incidence of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The total amount of the nano white zeolite and trace elements added to the aqueous solution is 8-10 wt.%.

5. The method for reducing the incidence of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The preparation method of the calcined diatomite is to calcine the diatomite at 500-600° C. for 1-2 hours.

6. The method for reducing the morbidity of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The base fertilizer is decomposed organic matter; the decomposed organic matter is prepared by mixing animal excrement and plant straw in a mass ratio of (2-3):10, decomposing for 1-2 weeks, and then drying and crushing to 10-20 meshes.

7. The method for reducing the incidence of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The trace elements are copper, iron, manganese, zinc, boron and molybdenum.

8. The method for reducing the morbidity of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The composite microbial agent comprises Bacillus subtilis, Trichoderma viride, actinomycetes and Trichoderma harzianum; the content of each fungus is ≥1 billion / g.

9. The method for reducing the morbidity of watermelon under high humidity and heat conditions according to claim 1, characterized in that: The mass ratio of the base fertilizer to the composite soil conditioner is 100:(4-6).

10. A method for growing watermelons in a hot and humid climate, characterized in that: In the early stage, the method for reducing the incidence of watermelon under high humidity and heat conditions as described in any one of claims 1 to 9 is used to reduce the incidence of watermelon, and in the later stage, conventional water and fertilizer management is carried out.

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