Watermelon sweetening cultivation method

Abstract

The invention relates to a watermelon sweetening cultivation method. The watermelon sweetening cultivation method comprises the following steps: S1, applying a thoroughly decomposed organic fertilizer and a potassium-magnesium compound fertilizer which are uniformly mixed into soil as a base fertilizer before planting; s2, atomizing and spraying sweeteners to leaf surfaces and flowers of the watermelons in flowering and fruit setting periods; s3, a sweetener is sprayed to leaf surfaces from a watermelon fruit swelling period to a watermelon fruit maturation period, a nursing blender is sprayed to the surfaces of the watermelon fruits, and a nursing blender is sprayed to the surfaces of the watermelon fruits; the nursing blender is prepared from the following raw materials in parts by weight: 5 to 16 parts of beewax, 2 to 7 parts of porous calcium particles, 1 to 3 parts of seaweed extract, 0.5 to 3 parts of fructo-oligosaccharide, 0.5 to 1.5 parts of glycerol, 0.8 to 1.5 parts of span-80 and 70 to 90 parts of distilled water. The problem of how to reduce the poor sweetness from the center of the watermelon to the surface layer of the watermelon can be solved, the overall sweetness of the watermelon can be improved, and the watermelon explosion rate can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of watermelon cultivation, and in particular relates to a watermelon sweetening cultivation method. Background Art

[0002] As one of the most popular summer fruits, watermelon's sweetness is a key factor influencing consumer purchasing behavior and market value. Research shows that for every 1° (Brix) increase in watermelon sweetness, consumer purchase intention increases by 15%-20%. In the high-end fruit market, high-sweetness watermelons often command higher premiums. However, traditional cultivation methods have long focused more on increasing yield and controlling pests and diseases, with relatively insufficient attention paid to optimizing sweetness. As a result, despite ample watermelon production, many products lack sweetness, making it difficult to meet consumer demand for high-quality watermelon. This is particularly pronounced in the high-end consumer segment, where the supply-demand imbalance is even more pronounced.

[0003] To increase the sweetness of watermelons, fruit farmers typically take measures to rationally control the application of potassium and nitrogen fertilizers. Potassium fertilizers can promote the synthesis and transport of sugars, while appropriate nitrogen fertilizer control helps prevent excessive plant growth and allows more photosynthetic products to flow to the fruit. However, although these measures can effectively increase the central sweetness of watermelons, the problem of uneven sweetness distribution remains widespread. Specifically, the sweetness of the watermelon flesh shows a significant downward trend from the center to the outer rind, with the sweetness of the area closer to the rind being significantly lower. This uneven sweetness not only affects consumers' overall eating experience but also becomes a major technical bottleneck in improving watermelon quality. Summary of the Invention

[0004] The invention provides a watermelon sweetening cultivation method for solving the problem of how to improve the sweetness of watermelons and reduce the sweetness difference of individual watermelons.

[0005] The technical solution adopted by the present invention is:

[0006] A watermelon sweetening cultivation method comprises the following steps:

[0007] S1. Apply a well-mixed mixture of decomposed organic fertilizer and potassium-magnesium compound fertilizer to the soil as base fertilizer before planting;

[0008] S2. During the flowering and fruiting period, spray the leaves and flowers of watermelon with a mist of sweetener, once every 7 days, for a total of 2 sprays;

[0009] S3, spraying the leaves with sweetener from the watermelon fruit expansion stage to the ripening stage, spraying the watermelon fruit surface with a nursing blending agent, spraying once every 7 days, spraying twice in total, spraying the watermelon fruit surface with a nursing blending agent, spraying once every 9 days, spraying twice in total;

[0010] The care blend comprises the following raw materials in parts by weight: 5-16 parts of beeswax, 2-7 parts of porous calcium particles, 1-3 parts of seaweed extract, 0.5-3 parts of oligofructose, 0.5-1.5 parts of glycerin, 0.8-1.5 parts of Span-80 and 70-90 parts of distilled water.

[0011] Furthermore, the care blend comprises the following raw materials in parts by weight: 10 parts of beeswax, 4 parts of porous calcium particles, 2 parts of seaweed extract, 2 parts of oligofructose, 1 part of glycerin, 1 part of Span-80 and 80 parts of distilled water.

[0012] Furthermore, the method comprises the following steps of preparing the porous calcium particles:

[0013] A1. Grind and sieve calcium carbonate to 9-11 μm, and prepare a 0.9-1.1 mol / L citric acid solution;

[0014] A2. Mix 0.9-1.1 g of calcium carbonate with 20 mL of citric acid aqueous solution, stir evenly with a magnetic stirrer at 240-260 rpm, and stir for 35-45 minutes.

[0015] A3. Freeze-dry at -45°C-55°C until dry, and calcine at 280°C-310°C for 100-130 minutes;

[0016] A4. Obtain 9-11 μm porous calcium particles by mechanical crushing and sieving.

[0017] Furthermore, the preparation steps of the nursing blend are included:

[0018] B1. Heat distilled water to 69-73°C, add beeswax, glycerin, and Span-80, and stir evenly with a magnetic stirrer at 240-260 rpm for 50-65 minutes.

[0019] B2. Adjust the temperature to 20-28°C and add porous calcium particles, seaweed extract and oligofructose. Stir with a magnetic stirrer at 240-260 rpm to mix evenly for 50-70 minutes.

[0020] Furthermore, the beeswax extraction method is as follows: placing the honeycomb after removing the pupae on a 190-210 mesh stainless steel sieve, using a steam wax melting method at 70° C.-80° C., and collecting the dripping wax liquid.

[0021] Furthermore, the method comprises the following steps of extracting the seaweed extract:

[0022] C1. Grind the naturally air-dried seaweed and sieve it through a 280-310 mesh screen;

[0023] C2. Mix 4-6 parts of seaweed powder and 60 parts of distilled water by mass, stir evenly with a magnetic stirrer at 240-260 rpm for 20-40 minutes, and ultrasonically treat at 45-55 kHz for 20-40 minutes during stirring;

[0024] C3. Filter out the seaweed with a 340-360 mesh filter and then freeze-dry at -45℃-55℃.

[0025] Furthermore, the seaweed is Ascophyllum nodosum.

[0026] Furthermore, the decomposed organic fertilizer includes the following raw materials in parts by weight: 583-624 parts of sheep manure, 195-215 parts of soybean meal, 143-161 parts of corn straw, 25-36 parts of humic acid, 17-23 parts of phosphate rock powder and 0.3-0.7 parts of EM bacterial agent; the potassium-magnesium compound fertilizer uses potassium magnesium sulfate; and 140-163 parts of decomposed organic fertilizer and 0.8-1.2 parts of potassium-magnesium compound fertilizer are mixed by weight as base fertilizer.

[0027] Furthermore, the base fertilizer is applied to the melon field at 2800 to 3200 kg / mu.

[0028] Furthermore, the sweetener is Repson sweetener, and 0.8-1.2 ml of the sweetener is diluted with 1 L of distilled water before spraying.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] When the care blend is sprayed on the watermelon rind, a breathable protective film forms on the surface. This film reduces water loss through the hydrophobic effect of beeswax and prevents the watermelon from bursting due to rainwater penetration. The microporous structure of the porous calcium particles further enhances air permeability, promoting the growth of the fruit. Furthermore, the porous calcium particles slowly release calcium ions, some of which is absorbed through microcracks or pores in the epidermis, helping to strengthen the cell wall structure and reduce the risk of fruit cracking. The active ingredients in seaweed extract can regulate the synthesis and signaling of endogenous plant hormones, promote vascular development, and optimize nutrient transport efficiency. Fructooligosaccharides, as soluble sugars, can penetrate the watermelon rind and directly replenish sugar precursors. They also regulate plant sugar signaling pathways, promote the expression of sucrose transporters (SUTs), and enhance the uniform transport of sugars into the fruit. Watermelons sprayed with the care blend have enhanced sugar loading capacity from the phloem to the center, reducing the difference in sweetness between the center and the cortex, and increasing the sweetness of the watermelon. DETAILED DESCRIPTION

[0031] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0032] Example 1

[0033] A watermelon sweetening cultivation method comprises the following steps:

[0034] S1. Apply a well-mixed mixture of decomposed organic fertilizer and potassium-magnesium compound fertilizer to the soil as base fertilizer before planting;

[0035] The decomposed organic fertilizer includes the following raw materials by weight: 585 parts of sheep manure, 195 parts of soybean meal, 143 parts of corn straw, 25 parts of humic acid, 17 parts of phosphate rock powder, and 0.3 parts of EM microbial agent; the potassium-magnesium compound fertilizer uses potassium magnesium sulfate; 140 parts of the decomposed organic fertilizer and 0.8 parts of the potassium-magnesium compound fertilizer are mixed as base fertilizer by weight; the base fertilizer is applied to the melon field at 2800 kg / mu;

[0036] The above base fertilizer is a rational combination of organic and non-basic fertilizers. This base fertilizer lays the key foundation for sweetening watermelons. The sheep manure, soybean meal, corn straw, and phosphate rock in the decomposed organic fertilizer provide comprehensive nutrients. Humic acid improves soil structure and enhances fertilizer and water retention. EM agents promote microbial activity, which is beneficial to root growth and nutrient absorption in watermelons, laying a solid foundation for sugar accumulation. The potassium in the potassium-magnesium compound fertilizer promotes photosynthesis and sugar transport, while magnesium ensures chlorophyll synthesis and increases photosynthetic intensity. The combination of the two, with complementary nutrients, improves fertilizer utilization and meets the needs of watermelons at different growth stages. It supports plant development in the early stages of growth and ensures fruit quality in the middle and late stages, creating favorable conditions for sweetening watermelons in all aspects.

[0037] S2. During the flowering and fruiting period, spray the watermelon leaves and flowers with a mist of sweetener, at least once every 7 days, for a total of 2 sprays. Dilute 0.8 ml of sweetener with 1 L of distilled water and spray evenly on the front and back of the leaves and flowers, until they are moist and drip-free.

[0038] As mentioned above, during the flowering and fruiting period of watermelon, spray the leaves and flowers with the sweetener Repson, twice with an interval of 7 days. This can not only promote sugar accumulation, lay the foundation for improving the sweetness and internal quality of watermelon and making the flesh plump and juicy, but also attract insects to pollinate the flowers and increase the fruit yield.

[0039] S3. Spray the leaves with a sweetener from the fruit expansion stage to the ripening stage, spraying once every 7 days for a total of 2 times; spray the surface of the watermelon fruit with a care blender, spraying once every 9 days for a total of 2 times;

[0040] As described above, the sweetener is sprayed on the leaves from the watermelon fruit expansion period to the ripening period, once every 9 days, for 2 times, to further supplement the large amount of sugar required for the watermelon fruiting and expansion period, and the care blender is sprayed on the surface of the watermelon fruit.

[0041] The care blend comprises the following ingredients in parts by weight: 5 parts beeswax, 2 parts porous calcium particles, 1 part seaweed extract, 0.5 parts oligofructose, 0.5 parts glycerin, 0.8 parts Span-80 and 70 parts distilled water;

[0042] When the conditioning agent is sprayed on the watermelon rind, it forms a breathable protective film. This film reduces water loss through the hydrophobic effect of beeswax and prevents the watermelon from bursting due to rainwater penetration. The microporous structure of the porous calcium particles further enhances air permeability, promoting the growth of the fruit. Furthermore, the porous calcium particles slowly release calcium ions, some of which is absorbed through microcracks or stomata in the epidermis, helping to strengthen the cell wall structure and reduce the risk of fruit cracking. The active ingredients in seaweed extract can regulate the synthesis and signaling of endogenous plant hormones, promote vascular development, and optimize nutrient transport efficiency. Fructooligosaccharides, as soluble sugars, can penetrate the watermelon rind and directly replenish sugar precursors. They also regulate plant sugar signaling pathways, promote the expression of sucrose transporters (SUTs), and enhance the uniform transport of sugars to the inner part of the fruit. Watermelons sprayed with the conditioning agent exhibit enhanced sugar loading from the phloem to the center, reducing the difference in sweetness between the center and the cortex, and increasing the sweetness of the fruit.

[0043] The preparation steps of porous calcium microparticles include the following:

[0044] A1. Grind and sieve calcium carbonate to 9 μm and prepare a 0.9 mol / L citric acid solution.

[0045] A2, mixed 0.9g calcium carbonate: 20mL citric acid aqueous solution, stirred at 240rpm with magnetic stirring, stirred for 35 minutes, and reacted to form calcium citrate;

[0046] A3. Freeze-dry at -45°C until dry. Low-temperature drying can preserve the porous skeleton structure of the reaction product and avoid pore collapse caused by room-temperature drying. Calcination at 280°C for 100 minutes decomposes calcium citrate to form porous calcium carbonate, while releasing CO2 and volatile organic compounds, forming a stable through-microporous / mesoporous structure.

[0047] A4. Obtain 9 μm porous calcium particles by mechanical crushing and sieving.

[0048] The porous calcium particles prepared above have good air permeability and can be used to further improve the air permeability of the protective film.

[0049] The extraction steps of seaweed extract include the following:

[0050] C1. Grind the naturally air-dried Ascophyllum nodosum and sieve it through a 280-mesh sieve;

[0051] C2. Mix 4 parts of seaweed powder with 60 parts of distilled water by mass, stir evenly with a magnetic stirrer at 240 rpm for 20 minutes, and simultaneously sonicate at 45 kHz for 20 minutes to break down the cell walls and facilitate the absorption of nutrients.

[0052] C3, filter out the seaweed with 340 mesh, and then freeze-dry at -45℃;

[0053] The above can better retain the active ingredients of Ascophyllum nodosum, which is beneficial for absorption by the watermelon skin.

[0054] Beeswax extraction method is as follows: place the honeycomb after pupae removal on a 190-mesh stainless steel sieve, use the steam wax melting method at 70°C, and collect the dripping wax liquid;

[0055] Above, high-purity natural honey can be prepared.

[0056] The steps for preparing the nursing blend include the following:

[0057] B1. Heat distilled water to 69°C, add beeswax, glycerin, and Span-80, and mix thoroughly using a magnetic stirrer at 240 rpm for 50 minutes. This allows the Span-80 to fully emulsify the beeswax and glycerin in the water.

[0058] B2. Adjust the temperature to 20°C and add the porous calcium particles, seaweed extract, and oligofructose. Mix them evenly with a magnetic stirrer at 240 rpm for 50 minutes to allow the mixture to float and be thoroughly mixed.

[0059] As described above, first heating the beeswax, glycerin and Span-80 for emulsification is beneficial to improving the emulsification effect of beeswax and glycerin, and then mixing and emulsifying with other components after cooling can avoid mixing at high temperature to affect the activity of other components.

[0060] Example 2

[0061] A watermelon sweetening cultivation method comprises the following steps:

[0062] S1. Apply a well-mixed mixture of decomposed organic fertilizer and potassium-magnesium compound fertilizer to the soil as base fertilizer before planting;

[0063] The decomposed organic fertilizer includes the following raw materials by weight: 624 parts of sheep manure, 215 parts of soybean meal, 161 parts of corn straw, 36 parts of humic acid, 23 parts of phosphate rock powder, and 0.7 parts of EM microbial agent; the potassium-magnesium compound fertilizer uses potassium magnesium sulfate; 163 parts of the decomposed organic fertilizer and 1.2 parts of the potassium-magnesium compound fertilizer are mixed as a base fertilizer by weight; the base fertilizer is applied to the melon field at 3200 kg / mu;

[0064] S2. During the flowering and fruiting period, the leaves and flowers of the watermelon were sprayed with a sweetener by mist spraying, with an interval of 7 days and a total of 2 sprays. 1.2 ml of the sweetener was diluted with 1 L of distilled water and sprayed evenly on the front and back of the leaves and flowers, until they were moist and not dripping.

[0065] S3. Spray the leaves with a sweetener from the fruit expansion stage to the ripening stage, spraying at least once every 7 days for a total of 2 times; spray the surface of the watermelon fruit with a care blender, spraying once every 9 days for a total of 2 times;

[0066] The care blend comprises the following ingredients in parts by weight: 16 parts beeswax, 7 parts porous calcium particles, 3 parts seaweed extract, 3 parts oligofructose, 1.5 parts glycerin, 1.5 parts Span-80 and 90 parts distilled water;

[0067] The preparation steps of porous calcium microparticles include the following:

[0068] A1. Grind and sieve calcium carbonate to 11 μm and prepare a 1.1 mol / L citric acid solution.

[0069] A2, mixed 1.1g calcium carbonate: 20mL citric acid aqueous solution, stirred at 260rpm with magnetic stirring, stirred for 45 minutes, and reacted to form calcium citrate;

[0070] A3. Freeze-dry at -55°C until dry. Low-temperature drying can preserve the porous skeleton structure of the reaction product and avoid pore collapse caused by drying at room temperature. Calcinate at 310°C for 130 minutes.

[0071] A4. Obtain 11 μm porous calcium particles by mechanical crushing and sieving.

[0072] The porous calcium particles prepared above have good air permeability and can be used to further improve the air permeability of the protective film.

[0073] The extraction steps of seaweed extract include the following:

[0074] C1. Grind the naturally air-dried Ascophyllum nodosum and sieve it through a 310-mesh sieve;

[0075] C2. Mix 6 parts of seaweed powder and 60 parts of distilled water by mass, stir evenly with a magnetic stirrer at 260 rpm for 40 minutes, and simultaneously sonicate at 55 kHz for 40 minutes;

[0076] C3. Filter out the seaweed with a 360-mesh filter and then freeze-dry at -55°C.

[0077] Beeswax extraction method is as follows: place the honeycomb after pupae removal on a 210-mesh stainless steel sieve, use the steam wax melting method at 80°C, and collect the dripping wax liquid;

[0078] The steps for preparing the nursing blend include the following:

[0079] B1. Heat distilled water to 73°C, add beeswax, glycerin, and Span-80, and mix thoroughly using a magnetic stirrer at 260 rpm for 65 minutes. This allows the Span-80 to fully emulsify the beeswax and glycerin in the water.

[0080] B2. After adjusting the temperature to 28°C, add porous calcium particles, seaweed extract and oligofructose, and mix them evenly with a magnetic stirrer at 260 rpm for 70 minutes to float the mixture and mix it thoroughly.

[0081] Example 3

[0082] A watermelon sweetening cultivation method comprises the following steps:

[0083] S1. Apply a well-mixed mixture of decomposed organic fertilizer and potassium-magnesium compound fertilizer to the soil as base fertilizer before planting;

[0084] The decomposed organic fertilizer includes the following raw materials by weight: 600 parts of sheep manure, 200 parts of soybean meal, 150 parts of corn straw, 30 parts of humic acid, 20 parts of phosphate rock powder, and 0.5 parts of EM microbial agent; the potassium-magnesium compound fertilizer uses potassium magnesium sulfate; 150 parts of the decomposed organic fertilizer and 1 part of the potassium-magnesium compound fertilizer are mixed by weight as a base fertilizer; the base fertilizer is applied to the melon field at 3000 kg / mu;

[0085] S2. During the flowering and fruiting period, spray the watermelon leaves and flowers with a mist of sweetener, spraying once every 7 days for a total of 2 sprays. Dilute 1 ml of sweetener with 1 L of distilled water and spray evenly on the front and back of the leaves and flowers until they are moist and do not drip.

[0086] S3. Spray the leaves with a sweetener from the fruit expansion stage to the ripening stage, spraying at least once every 7 days for a total of 2 times; spray the surface of the watermelon fruit with a care blender, spraying once every 9 days for a total of 2 times;

[0087] The care blend comprises the following ingredients in parts by weight: 10 parts beeswax, 5 parts porous calcium microparticles, 2 parts seaweed extract, 2 parts oligofructose, 1 part glycerin, 1 part Span-80 and 82 parts distilled water;

[0088] The preparation steps of porous calcium microparticles include the following:

[0089] A1. Grind and sieve calcium carbonate to 10 μm and prepare a 1 mol / L citric acid solution.

[0090] A2. Mix 1 g of calcium carbonate with 20 mL of citric acid aqueous solution, stir at 250 rpm with a magnetic stirrer, and stir for 40 minutes to generate calcium citrate.

[0091] A3. Freeze-dry at -50°C until dry. Low-temperature drying can preserve the porous skeleton structure of the reaction product and avoid pore collapse caused by drying at room temperature. Calcinate at 300°C for 120 minutes.

[0092] A4. Obtain 10 μm porous calcium particles by mechanical crushing and sieving.

[0093] The porous calcium particles prepared above have good air permeability and can be used to further improve the air permeability of the protective film.

[0094] The extraction steps of seaweed extract include the following:

[0095] C1. Grind the naturally air-dried Ascophyllum nodosum and sieve it through a 300-mesh sieve;

[0096] C2. Mix 5 parts of seaweed powder and 60 parts of distilled water by mass, stir the mixture uniformly with a magnetic stirrer at 250 rpm for 30 minutes, and ultrasonicate at 50 kHz for 30 minutes;

[0097] C3. Filter out the seaweed with 350 mesh and then freeze-dry at -50℃.

[0098] Beeswax extraction method is as follows: place the honeycomb after pupae removal on a 200-mesh stainless steel sieve, use the steam wax melting method at 75°C, and collect the dripping wax liquid;

[0099] The steps for preparing the nursing blend include the following:

[0100] B1. Heat distilled water to 70°C, add beeswax, glycerin, and Span-80, and mix evenly with a magnetic stirrer at 250 rpm for 60 minutes to allow the Span-80 to fully emulsify the beeswax and glycerin in the water.

[0101] B2. After adjusting the temperature to 25°C, add porous calcium particles, seaweed extract and oligofructose, and mix them evenly with a magnetic stirrer at 250 rpm for 60 minutes to float the mixture and mix it thoroughly.

[0102] Comparative Example 1

[0103] The difference from Example 3 is:

[0104] In step S3, the step of "spraying the care blending agent onto the surface of the watermelon fruit" is omitted.

[0105] Comparative Example 2

[0106] The difference from Example 3 is:

[0107] In S3, during the period from the expansion stage to the ripening stage of watermelon fruits, spraying of the care blending agent was replaced by spraying of the sweetener.

[0108] Test results:

[0109] 5 mu of adjacent melon fields were selected to plant watermelons of the same variety. Every mu was planted according to the methods of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2. After the watermelons matured, 2 low-grade melons, 2 medium melons and 2 high-grade melons were randomly selected from every mu. The sweetness of each watermelon was detected by sampling in three mutually perpendicular and intersecting axis directions. The intersection of the three axes was located at the center of the watermelon. The sweetness was sampled and detected at the center of the watermelon, and the sweetness was sampled and detected at 1 cm from the white peel of the watermelon along the axis direction (sampling 6 places in total). The sweetness values at 6 edges of a single watermelon were added together to calculate the middle mean. The sweetness values at the centers of 6 watermelons of the same mu were added together to calculate the total mean. The middle mean values at 6 edges were added together to calculate the total mean. The total mean sweetness at the center was deducted from the total mean sweetness at the edges to obtain the sweetness difference. Luheng Biotechnology Digital Display Sugar Scale Meter LH-B55 was used for detection. The bursting rate of every mu of watermelon was counted, as shown in the table below:

[0110]

[0111]

[0112] As can be seen from the table above, after spraying the watermelon fruits with the care blend in Examples 1 to 3, the sweetness of the watermelons was significantly improved, the difference in sweetness between the center and the area near the white skin was significantly reduced, and the bursting rate was also significantly reduced, which can significantly improve the planting quality. Among them, Example 3 had the smallest sweetness difference and the smallest bursting rate.

[0113] In Comparative Example 1, after the spraying of the care blending agent was cancelled, the sweetness difference was large, the overall sweetness was low, and the bursting rate was high; in Comparative Example 2, after the care blending agent was replaced with a sweetener, the sweetness and sweetness difference were slightly improved compared with Comparative Example 1, but due to the lack of care for the outer layer of the watermelon, the outer layer of the watermelon developed poorly, its growth rate did not match that of the center, and the toughness of the outer layer was poor, which made the bursting rate significantly higher. In addition, due to the poor development of the outer layer, its ability to absorb sweeteners and transport nutrients was poor, and the sweetening effect was not obvious.

[0114] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A watermelon sweetening cultivation method, characterized in that: The following steps are included: S1. Apply a well-mixed mixture of decomposed organic fertilizer and potassium-magnesium compound fertilizer to the soil as base fertilizer before planting; S2. During the flowering and fruiting period, spray the leaves and flowers of watermelon with a mist of sweetener, once every 7 days, for a total of 2 sprays; S3, spraying the leaves with sweetener from the watermelon fruit expansion stage to the ripening stage, spraying the watermelon fruit surface with a nursing blending agent, spraying once every 7 days, spraying twice in total, spraying the watermelon fruit surface with a nursing blending agent, spraying once every 9 days, spraying twice in total; The care blend comprises the following raw materials in parts by weight: 5-16 parts of beeswax, 2-7 parts of porous calcium particles, 1-3 parts of seaweed extract, 0.5-3 parts of oligofructose, 0.5-1.5 parts of glycerin, 0.8-1.5 parts of Span-80 and 70-90 parts of distilled water.

2. A watermelon sweetening cultivation method according to claim 1, characterized in that: The care blend comprises the following raw materials in parts by weight: 10 parts beeswax, 5 parts porous calcium particles, 2 parts seaweed extract, 2 parts oligofructose, 1 part glycerin, 1 part Span-80 and 82 parts distilled water.

3. A watermelon sweetening cultivation method according to claim 1, characterized in that: The method comprises the following steps for preparing porous calcium particles: A1. Grind and sieve calcium carbonate to 9-11 μm, and prepare a 0.9-1.1 mol / L citric acid solution; A2. Mix 0.9-1.1 g of calcium carbonate with 20 mL of citric acid aqueous solution, stir evenly with a magnetic stirrer at 240-260 rpm, and stir for 35-45 minutes. A3. Freeze-dry at -45°C-55°C until dry, and calcine at 280°C-310°C for 100-130 minutes; A4. Obtain 9-11 μm porous calcium particles by mechanical crushing and sieving.

4. A watermelon sweetening cultivation method according to any one of claims 1 to 3, characterized in that: The preparation steps of the care blend include the following: B1. Heat distilled water to 69-73°C, add beeswax, glycerin, and Span-80, and mix thoroughly with a magnetic stirrer at 240-260 rpm for 50-65 minutes. B2. Adjust the temperature to 20-28°C and add porous calcium particles, seaweed extract and oligofructose. Stir with a magnetic stirrer at 240-260 rpm to mix evenly for 50-70 minutes.

5. The watermelon sweetening cultivation method according to claim 1, wherein: The beeswax extraction method comprises the following steps: placing a honeycomb after removing the pupae on a stainless steel sieve of 190-210 meshes, using a steam wax melting method at 70-80° C., and collecting dripping wax liquid.

6. The watermelon sweetening cultivation method according to claim 1, characterized in that: The extraction steps of the seaweed extract include the following: C1. Grind the naturally air-dried seaweed and sieve it through a 280-310 mesh screen; C2. Mix 4-6 parts of seaweed powder and 60 parts of distilled water by mass, stir evenly with a magnetic stirrer at 240-260 rpm for 20-40 minutes, and ultrasonically treat at 45-55 kHz for 20-40 minutes during stirring; C3. Filter out the seaweed with a 340-360 mesh filter and then freeze-dry at -45℃-55℃.

7. The watermelon sweetening cultivation method according to claim 6, characterized in that: The seaweed is Ascophyllum nodosum.

8. The watermelon sweetening cultivation method according to claim 1, characterized in that: The decomposed organic fertilizer comprises the following raw materials in parts by weight: 583-624 parts of sheep manure, 195-215 parts of soybean meal, 143-161 parts of corn straw, 25-36 parts of humic acid, 17-23 parts of phosphate rock powder and 0.3-0.7 parts of EM microbial agent; the potassium-magnesium compound fertilizer adopts potassium magnesium sulfate; and 140-163 parts of decomposed organic fertilizer and 0.8-1.2 parts of potassium-magnesium compound fertilizer are mixed as base fertilizer in parts by weight.

9. The watermelon sweetening cultivation method according to claim 8, characterized in that: The base fertilizer is applied to the melon field at 2800 to 3200 kg / mu.

10. The watermelon sweetening cultivation method according to claim 1, characterized in that: The sweetener used is Repson sweetener, and 0.8-1.2 ml of the sweetener is diluted with 1 L of distilled water before spraying.

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