Method for simultaneously increasing selenium content and sweetness of thick-skinned melon

Abstract

This invention belongs to the field of agricultural planting technology and provides a method for increasing the selenium content and sweetness of thick-skinned melons. Based on conventional management, this method employs a three-step sequential synergistic treatment: First, on the day the female flower opens, spray composition A onto the female flower, utilizing sulfur-containing amino acids to guide selenium rapidly into the organic selenium metabolic pathway, establishing a high-selenium pool in the fruit; second, when the young fruit reaches the size of an egg, spray composition B on the entire plant's leaves, promoting sucrose translocation to the fruit through the synergistic effect of hormones and betaine, and utilizing a silicon-calcium cross-linking layer to prevent fruit cracking; third, during the early and middle stages of fruit enlargement, drench the roots with composition C, activating soil mineral selenium through microbial metabolism to achieve continuous selenium supply. This invention reduces the fruit cracking rate to 1.0%–1.2%, increases the fruit selenium content to 0.21–0.28 mg / kg, and raises the soluble solids content to 16.2%–16.6%, achieving simultaneous improvement in selenium enrichment, high sweetness, and crack prevention in thick-skinned melons.

Description

Technical Field

[0001] This invention relates to the field of agricultural planting technology, and more specifically to a method for simultaneously increasing the selenium content and sweetness of thick-skinned melons. Background Technology

[0002] Thick-skinned melon (Cucumis melo L.) is an important economic crop widely cultivated in my country, favored by consumers for its sweetness, juiciness, and rich nutrition. In recent years, with the increasing awareness of healthy eating among residents, the market demand for functional melons rich in the essential trace element selenium has been expanding. Selenium is a key component of various selenoproteins, such as glutathione peroxidase, and has physiological functions such as antioxidation and immune enhancement. Safe selenium supplementation through diet has become an important nutritional intervention approach. Targeted fortification of selenium enrichment in thick-skinned melon production, and the development of melon products that combine high selenium content with excellent edible quality, are of great significance for increasing the added value of the industry.

[0003] Currently, the cultivation of thick-skinned melons with selenium mainly relies on foliar spraying or root application of inorganic selenium fertilizers such as sodium selenite. However, the assimilation efficiency of inorganic selenium in plants is limited, and it must be converted into organic selenium through sulfur metabolism to effectively accumulate and reduce toxicity. This conversion process requires a sufficient supply of sulfur-containing amino acid precursors and reducing power. Once the plant's metabolic load is exceeded, it can easily cause cumulative toxicity of inorganic selenium, inhibiting the activity of key enzymes in leaf photosynthesis and sucrose metabolism, leading to reduced fruit sweetness and flavor deterioration. Some studies have attempted to apply sodium selenite in simple combinations with amino acids, but because the treatment is only performed at a specific isolated growth stage, there is a lack of full-time regulation from flower organ development to fruit ripening. It is difficult to form an effective physiological coupling between selenoamino acid synthesis and sugar accumulation, and the simultaneous increase in organic selenium content and sweetness is not ideal.

[0004] The sweetness of thick-skinned melons mainly depends on the sufficient accumulation of soluble solids, especially sucrose, in the fruit. This process is controlled by the synergistic effects of photosynthetic product synthesis at the source, phloem loading and transport, and sink unloading metabolism. In production, methods such as adjusting the nitrogen-potassium ratio and supplementing with betaine or jasmonic acid are often used to improve photosynthetic efficiency and sugar transport. However, single measures have limited coordinating effects on source-sink flow, and the rapid sugar accumulation period often overlaps with the rapid fruit expansion period, making it highly susceptible to cracking due to insufficient pericarp cell wall strength. Once cracking occurs, the fruit loses its commercial value and can become a channel for pathogen infection, causing serious economic losses. Currently, preventing cracking mainly relies on supplementing with calcium and silicon nutrients to strengthen the peel structure. However, traditional calcium fertilizers have poor mobility in the phloem, and ordinary silicon fertilizers have weak leaf permeability, making it difficult to efficiently deposit in the peel tissue to form an effective protective layer, resulting in unstable crack prevention effects.

[0005] Furthermore, there is a complex interaction between selenium enrichment, sweetness enhancement, and crack prevention: excessive selenium supply can exacerbate oxidative stress, weaken photosynthetic capacity, and inhibit sugar accumulation; the intensive fertilization and irrigation management associated with high sugar content often increases the risk of fruit cracking. Most existing technologies focus on improving single objectives, lacking a technical solution that organically integrates targeted selenium enrichment, sufficient sugar accumulation, and physical protection of the fruit, making it difficult to leverage the synergistic effects of multiple measures. Therefore, there is an urgent need to develop a cultivation method that precisely links key growth stages, simultaneously increasing the selenium content and sweetness of thick-skinned melons while effectively reducing fruit cracking. Summary of the Invention

[0006] This invention aims to provide a method for simultaneously increasing the selenium content and sweetness of thick-skinned melons.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: a method for simultaneously increasing the selenium content and sweetness of thick-skinned melons, including conventional cultivation management, and further including the following steps:

[0008] S1. On the day the female flower opens, spray composition A evenly onto the female flower. Composition A includes: sodium selenite, cysteine, methionine, and surfactant.

[0009] S2. When the fruit develops to the size of an egg, spray the entire plant with composition B, which includes: methyl jasmonate, betaine, nano-silica-amino acid calcium complex, organoboron and spreading agent; the nano-silica-amino acid calcium complex is a mixture of nano-silica and amino acid calcium.

[0010] S3. Apply composition C to the roots once each in the early and middle stages of fruit enlargement. Composition C includes: brown sugar, peanut bran, compound microbial agent and maifanite powder. The compound microbial agent contains Bacillus megaterium, Saccharomyces cerevisiae, and Lactobacillus plantarum, with an effective live bacteria count ≥200 million / mL.

[0011] Further, in step S1, the composition and concentration of the composition A are as follows: sodium selenite 15-25 mg / L, cysteine ​​0.2-0.8 mmol / L, methionine 0.1-0.5 mmol / L, organosilicon surfactant 0.02%-0.1% (v / v), and the balance being water.

[0012] Further, in step S2, the composition and concentration of the composition B are as follows: methyl jasmonate 5-20 mg / L, betaine 50-200 mg / L, nano silica-amino acid calcium complex 200-500 mg / L, organoboron 30-80 mg / L, developing agent 0.05%-0.2% (v / v), and the balance is water; in the nano silica-amino acid calcium complex, the mass ratio of nano silica to amino acid calcium is 1:2-1:5.

[0013] Furthermore, the preparation method of the nano-silica-amino acid calcium complex is as follows: nano-silica is dispersed in deionized water, ultrasonically dispersed evenly, and then amino acid calcium solution is slowly added under stirring conditions. The mass ratio of nano-silica to amino acid calcium is controlled to be 1:2 to 1:5. The pH is adjusted to 6.0 to 7.0, and stirring is continued for 1 to 2 hours to obtain a stable complex suspension.

[0014] Further, in step S3, the dosage of composition C per mu is: 15-25 kg of brown sugar, 40-60 kg of peanut bran, 0.5-2.0 kg of compound microbial agent, and 5-10 kg of maifanite powder.

[0015] Furthermore, the timing for step S2 is as follows: when more than 80% of the young fruits in the field reach a diameter of 4-6 cm, spraying should be carried out after 4 pm on a sunny day. If it rains within 24 hours after spraying, re-spraying is required.

[0016] Furthermore, it also includes applying a foliar spray of Composition B once during the late stage of fruit enlargement to 7 days before maturity, wherein the concentration of methyl jasmonate is 3-10 mg / L, the concentration of betaine is 30-100 mg / L, the concentration of nano-silica-amino acid calcium complex is 100-300 mg / L, and the concentration of organic boron is 20-50 mg / L, in order to strengthen the fruit peel skeleton.

[0017] In this invention, the compound microbial agent is a commercially available product, and examples of manufacturers are as follows:

[0018] Product Name: VT Microbial Agent; Manufacturer: Beijing Wotu Tiandi Biotechnology Co., Ltd.; Registration Certificate No.: Microbial Fertilizer (2005) Approval No. (0197).

[0019] The amino acid calcium is a commercially available product, and examples of manufacturers are as follows:

[0020] Product Name: Amino Acid Calcium; Manufacturer: Shandong Lvlong Biotechnology Co., Ltd.; Technical Specifications: Ca≥100g / L; Registration Number: ZLSRSD2021-00591.

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

[0022] This invention forms an interconnected system of "foundation-strengthening-sustained operation" along the timeline of "female flower opening → young fruit stage → fruit enlargement stage". Through the coordinated regulation of source, flow and sink, it ultimately achieves the comprehensive effect of simultaneously improving selenium and sweetness and significantly reducing fruit cracking.

[0023] During the flowering and fruit setting stage, composition A rapidly introduces sodium selenite into the organic selenium conversion pathway via the sulfhydryl groups of cysteine ​​and methionine, pre-setting a high-selenium metabolic program for young fruits and stabilizing sink organs such as the ovary using the physiological activity of sulfur-containing amino acids. This early foundational treatment lays the groundwork for crucial "demand signals" in subsequent steps—the greater the sink strength, the stronger the pull on root nutrients. Entering the fruit enlargement stage, the complex microbial community in composition C, including Bacillus megaterium and Saccharomyces cerevisiae, under the nourishment of brown sugar and peanut bran, metabolizes large amounts of organic acids to activate soil mineral selenium, continuously supplying the plant with available selenium. At this time, the fruit sink strength enhanced by composition A in the early stage can efficiently pull the selenium released from the roots into the fruit and convert it into selenoproteins, avoiding ineffective absorption and loss, forming a relay mode of "initiating selenium metabolism in the early stage and enriching selenium accumulation in the later stage."

[0024] Meanwhile, Composition B and Composition C established a bidirectional complementary channel between the aboveground and underground parts of the plant. After foliar spraying with Composition B, methyl jasmonate and betaine synergistically enhanced the photosynthetic efficiency of the leaves and the loading capacity of sucrose into the phloem of the fruit, creating a powerful "siphon" nutrient transport. This provided a clear aboveground pull for the carbon source and mineral elements supplemented by Composition C from the roots, enabling the nutrients released by microbial metabolism to be rapidly transported to the fruit. Conversely, the amino acids, polysaccharides, and other secondary metabolites secreted by the functional bacteria in Composition C continuously nourished the roots, maintaining vigorous absorption activity, and ensuring that the strong photosynthesis induced by Composition B received sufficient water and mineral support. The two factors, one above and one below, mutually promoted the synthesis of photosynthetic products and the activation of soil nutrients, keeping the melon in a state of vigorous carbon and nitrogen metabolism and smooth source-sink flow during the expansion period, thereby driving the soluble solids content to increase by 0.9–1.3 percentage points compared with the conventional control.

[0025] More importantly, the high-intensity operation of the above-ground strong flow and underground open source is also embedded with a defensive protection layer that runs through the entire process. The nano-silica-amino acid calcium complex in composition B forms a dense silicon-calcium cross-linked protective layer under the cuticle of the fruit peel during the young fruit stage, significantly thickening the cell wall. This not only greatly reduces the risk of fruit cracking during the expansion period, but also provides structural support for the rapid expansion pulse caused by the subsequent root drenching of composition C. A low-concentration supplemental spray of composition B in the later stage of fruit expansion further consolidates the skeletal strength, enabling the long-lasting nutrients activated by composition C to be safely and continuously converted into yield and sweetness.

[0026] In summary, this invention achieves a precise sequential effect and deep functional complementarity, fusing the targeted enrichment of selenium, the full accumulation of sugar, and the physical protection of fruit structure into a unified whole, ultimately achieving the outstanding effect of selenium enrichment, high sweetness, and crack prevention in one. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The following is an example of conventional cultivation and management described in this invention:

[0029] 1. Sowing and seedling raising

[0030] (1) Soaking and germination: Soak the melon seeds in 55℃ warm water for 15 minutes, take them out and put them in 1% potassium permanganate + 10% trisodium phosphate solution for 20 minutes to disinfect them, rinse them with clean water, soak them at room temperature for 6 hours, take them out and drain them, and germinate them at 28-30℃ until 60% of the seeds show white.

[0031] (2) Sowing: Seedlings are raised in nutrient pots. The nutrient soil is composed of 80% pond mud and 20% well-rotted organic fertilizer. 5 kg of calcium magnesium phosphate fertilizer and 2 kg of potassium sulfate compound fertilizer are added to each cubic meter of nutrient soil and mixed well. Before sowing, the soil in the pots is thoroughly watered. After sowing, cover with 1 cm of fine soil or peat moss and then water to keep it moist.

[0032] (3) Seedling management: Seedlings emerge 2-3 days after sowing. After emergence, strengthen ventilation and light penetration, control water to prevent excessive growth, thin seedlings 1-2 times after emergence, remove overly dense, weak and diseased seedlings, and prevent damping-off and seedling blight in a timely manner.

[0033] 2. Soil selection

[0034] Select plots with good drainage, high organic matter content, and soil selenium content greater than 0.4 mg / kg.

[0035] 3. Prepare the land and apply base fertilizer

[0036] When the soil moisture content is below 60%, rotary tillage should be carried out per mu. Apply 2000-3000 kg of well-rotted chicken manure, pig manure and other organic fertilizers, as well as 50 kg of long-acting compound fertilizer with N:P2O5:K2O ratio of 15:15:15 per mu. After tilling and breaking up the soil, make ridges with a ridge width of 1.0 meter, a ridge height of 0.3 meters and a ditch width of 0.4 meters, and cover with mulch film.

[0037] 4. Planting

[0038] Transplant seedlings when they have 5-6 true leaves. Three days before transplanting, spray with a mixture of 1500x azoxystrobin, 800x mancozeb, and 2000x abamectin to prevent disease. Water thoroughly one day before lifting the seedlings, keeping a soil ball around each seedling. For single-stem pruning, space the plants 30-35cm apart and the rows 50-60cm apart, approximately 3000-3200 plants per acre; for double-stem pruning, space the plants 60-70cm apart and the rows 50-60cm apart, approximately 1500-1800 plants per acre. Water thoroughly after planting, and water again 4-5 days later to help the seedlings establish.

[0039] 5. Water and fertilizer management

[0040] Following the principle of controlling the initial stage, promoting the middle stage, and attacking the final stage, the topdressing fertilizers used do not contain any additional functional ingredients of this invention, such as selenium.

[0041] (1) From transplanting to the seedling stage: Do not water if the soil is dry. You can apply a foliar spray of a mixture of 0.3-0.5% urea and 0.5% potassium dihydrogen phosphate once.

[0042] (2) From the seedling stage to the vine extension stage: apply high nitrogen water-soluble fertilizer 1-2 times (N:P2O5:K2O is 20:10:15), with a dosage of 3-5 kg ​​per mu.

[0043] (3) In the early stage of fruit enlargement (approximately 200 grams of fruit weight): apply 10-15 kg of high-potassium water-soluble fertilizer per mu (N:P2O5:K2O = 15:10:20).

[0044] (4) During the middle stage of fruit enlargement (approximately 500 grams of fruit weight): apply 10-15 kg of high-potassium water-soluble fertilizer per mu (N:P2O5:K2O = 15:10:20).

[0045] 6. Plant adjustment

[0046] Trellising, pruning, and fruit setting are carried out as usual. When pruning a single vine, remove all lateral shoots below the 12th node of the main vine, leaving lateral shoots at the 13th-16th nodes as fruiting vines. Remove lateral shoots at the 17th-24th nodes promptly. Pinch off the main vine at the 25th leaf stage, and repeatedly pinch off the tips of lateral shoots above the 25th node, leaving only 2 leaves. When the young fruit is about the size of an egg, select one fruit with a low node and a regular shape, and remove the rest.

[0047] 7. Pest and disease control

[0048] For diseases such as damping-off, wilt, viral diseases, downy mildew, anthracnose, gray mold, bacterial angular leaf spot, root-knot nematode disease, whiteflies, aphids, cotton bollworms, spider mites, and American serpentine leafminers, the recommended pesticides are used in rotation according to conventional methods. The specific procedures are the same as general production procedures and will not be elaborated here. Furthermore, the application of all pesticides will not antagonize the special treatment of this invention within the same time window.

[0049] Example 1

[0050] Based on conventional cultivation and management, strictly follow these steps:

[0051] S1. On the day the female flower opens, spray the female flower evenly with composition A, the composition and concentration of which are: sodium selenite 15 mg / L, cysteine ​​0.2 mmol / L, methionine 0.1 mmol / L, polyether-modified trisiloxane 0.02% (v / v), and the balance is water.

[0052] S2. When more than 80% of the young fruits in the field reach a diameter of 4-6 cm (the fruit develops to the size of an egg), spray the entire plant with Composition B after 4 pm on a sunny afternoon. If it rains within 24 hours after spraying, re-spraying is required. The composition and concentration of Composition B are: methyl jasmonate 5 mg / L, betaine 50 mg / L, nano-silica-amino acid calcium complex 200 mg / L, sorbitol boron 30 mg / L, fatty alcohol polyoxyethylene ether 0.05% (v / v), and the balance is water. In the nano-silica-amino acid calcium complex, the mass ratio of nano-silica to amino acid calcium is 1:2. The preparation method of the nano-silica-amino acid calcium complex is as follows: disperse nano-silica in deionized water, ultrasonically disperse until uniform, slowly add amino acid calcium solution under stirring, control the mass ratio of nano-silica to amino acid calcium at 1:2, adjust the pH to 6.5, and continue stirring for 1.5 hours to obtain a stable complex suspension.

[0053] S3. Apply Composition C to the roots once during the early stage (approximately 200g) and once during the middle stage (approximately 500g). Dilute Composition C with 500 L / mu of water and apply evenly. The dosage of Composition C per mu is: 15 kg of brown sugar, 40 kg of peanut bran, 0.5 kg of compound microbial agent, and 5 kg of maifanite powder. The compound microbial agent contains Bacillus megaterium, Saccharomyces cerevisiae, and Lactobacillus plantarum, with an effective viable count ≥200 million / mL.

[0054] It also includes a foliar spray of Composition B, applied once during the late fruit enlargement stage to 7 days before maturity, wherein the concentration of methyl jasmonate is 3 mg / L, the concentration of betaine is 30 mg / L, the concentration of nano-silica-amino acid calcium complex is 100 mg / L, and the concentration of organic boron is 20 mg / L.

[0055] Example 2

[0056] Based on conventional cultivation and management, strictly follow these steps:

[0057] S1. On the day the female flower opens, spray the female flower evenly with composition A, wherein the composition and concentration of composition A are: sodium selenite 20 mg / L, cysteine ​​0.5 mmol / L, methionine 0.3 mmol / L, polyether-modified trisiloxane 0.06% (v / v), and the balance is water.

[0058] S2. When more than 80% of the young fruits in the field reach a diameter of 4-6 cm (the fruit develops to the size of an egg), spray the entire plant with Composition B after 4 pm on a sunny afternoon. If it rains within 24 hours after spraying, re-spray. The composition and concentration of Composition B are as follows: methyl jasmonate 12.5 mg / L, betaine 125 mg / L, nano-silica-amino acid calcium complex 350 mg / L, sorbitol boron 55 mg / L, polyether-modified trisiloxane 0.125% (v / v), and the balance is water. In the nano-silica-amino acid calcium complex, the mass ratio of nano-silica to amino acid calcium is 1:3.5. The preparation method of the nano-silica-amino acid calcium complex is as follows: disperse nano-silica in deionized water, ultrasonically disperse it evenly, and then slowly add amino acid calcium solution under stirring, controlling the mass ratio of nano-silica to amino acid calcium at 1:3.5, adjusting the pH to 6.5, and continuing to stir for 1.5 hours to obtain a stable complex suspension.

[0059] S3. Apply Composition C to the roots once during the early stage (approximately 200g) and once during the middle stage (approximately 500g). Dilute Composition C with 500 L / mu of water and apply evenly. The dosage of Composition C per mu is: 20 kg brown sugar, 50 kg peanut bran, 1.25 kg compound microbial agent, and 7.5 kg maifanite powder. The compound microbial agent contains Bacillus megaterium, Saccharomyces cerevisiae, and Lactobacillus plantarum, with an effective viable count ≥200 million / mL.

[0060] It also includes a foliar spray of Composition B once during the late fruit enlargement stage to 7 days before maturity, in which the concentration of methyl jasmonate is 6.5 mg / L, the concentration of betaine is 65 mg / L, the concentration of nano-silica-amino acid calcium complex is 200 mg / L, and the concentration of organic boron is 35 mg / L.

[0061] Example 3

[0062] Based on conventional cultivation and management, strictly follow these steps:

[0063] S1. On the day the female flower opens, spray composition A evenly onto the female flower. The composition and concentration of composition A are as follows: sodium selenite 25 mg / L, cysteine ​​0.8 mmol / L, methionine 0.5 mmol / L, polyether-modified trisiloxane 0.1% (v / v), and the balance is water.

[0064] S2. When more than 80% of the young fruits in the field reach a diameter of 4-6 cm (the fruit develops to the size of an egg), spray the entire plant with Composition B after 4 pm on a sunny afternoon. If it rains within 24 hours after spraying, re-spraying is required. The composition and concentration of Composition B are: methyl jasmonate 20 mg / L, betaine 200 mg / L, nano-silica-amino acid calcium complex 500 mg / L, sorbitol boron 80 mg / L, fatty alcohol polyoxyethylene ether 0.2% (v / v), and the balance is water. In the nano-silica-amino acid calcium complex, the mass ratio of nano-silica to amino acid calcium is 1:5. The preparation method of the nano-silica-amino acid calcium complex is as follows: disperse nano-silica in deionized water, ultrasonically disperse it evenly, and then slowly add amino acid calcium solution under stirring, controlling the mass ratio of nano-silica to amino acid calcium at 1:5, adjust the pH to 6.5, and continue stirring for 1.5 hours to obtain a stable complex suspension.

[0065] S3. Apply Composition C to the roots once during the early stage (approximately 200g) and once during the middle stage (approximately 500g). Dilute Composition C with 500 L / mu of water and apply evenly. The dosage of Composition C per mu is: 25 kg brown sugar, 60 kg peanut bran, 2.0 kg compound microbial agent, and 10 kg maifanite powder. The compound microbial agent contains Bacillus megaterium, Saccharomyces cerevisiae, and Lactobacillus plantarum, with an effective viable count ≥200 million / mL.

[0066] It also includes a foliar spray of Composition B, applied once during the late fruit enlargement stage to 7 days before maturity, wherein the concentration of methyl jasmonate is 10 mg / L, the concentration of betaine is 100 mg / L, the concentration of nano-silica-amino acid calcium complex is 300 mg / L, and the concentration of organoboron is 50 mg / L.

[0067] Unless otherwise specified, the solvent for the drug dilutions used in the cultivation of thick-skinned melons in this application is water.

[0068] Compare with Example 1

[0069] Based on conventional cultivation and management, only on the day the female flower opens, spray Composition A. The composition and concentration of Composition A are the same as in Example 1 (i.e., sodium selenite 15 mg / L, cysteine ​​0.2 mmol / L, methionine 0.1 mmol / L, polyether modified trisiloxane 0.02%). Steps S2 and S3 and the operation of spraying Composition B in the later stage of fruit enlargement are not performed.

[0070] Compare with Example 2

[0071] Based on conventional cultivation and management, only steps S2 and S3 are performed. The composition, concentration, and usage of composition B and composition C are the same as in Example 1, but step S1 is not performed (i.e., composition A is not sprayed on the day the female flower opens).

[0072] Comparative Example 3 (Standardized Control)

[0073] Conventional cultivation management is performed without applying any of the compositions A, B, and C of this invention, nor with related spraying or drenching.

[0074] Compare with Example 4

[0075] Based on conventional cultivation and management, only steps S1 and S2 are performed. The composition, concentration, and usage of composition A and composition B are the same as in Example 1, but step S3 and the operation of spraying composition B during the later stage of fruit enlargement are not performed.

[0076] Compare with Example 5

[0077] Based on conventional cultivation and management, only steps S1 and S3 are performed. The composition, concentration, and usage of composition A and composition C are the same as in Example 1, but step S2 and the operation of spraying composition B during the later stage of fruit enlargement are not performed.

[0078] To further illustrate the technical effects achievable by this invention, thick-skinned melons were planted in an experimental group, and the fruit cracking rate, fruit set rate, average single fruit weight, soluble solids content, and selenium content of the fruit were recorded. The experimental results are shown in Table 1 below.

[0079] Table 1. Test Results

[0080]

[0081] As shown in Table 1, Examples 1-3 of the present invention are significantly superior to the control examples in terms of fruit cracking rate, average single fruit weight, soluble solids content, and fruit selenium content. Among them, Example 2 has the best overall effect, with a fruit cracking rate of only 1.0%, a fruit selenium content of 0.26 mg / kg, and a soluble solids content of 16.6%.

[0082] Control Example 4, lacking the continuous selenium supply step of root activation mineral selenium, had fruit selenium content (0.16 mg / kg) and soluble solids (15.9%) that were better than those of Control Example 3, but significantly lower than those of Example 1 (0.21 mg / kg, 16.2%). Its fruit cracking rate (3.6%) was also higher than that of Example 1 (1.2%), demonstrating that the absence of step S3 leads to insufficient selenium accumulation and reduced crack prevention effect. Control Example 5, lacking the leaf sugar transport enhancement and peel reinforcement steps, had soluble solids (15.7%) that were slightly higher than those of Control Example 1, but its fruit cracking rate (5.1%) surpassed that of Control Example 1 (4.8%). Its fruit selenium content (0.13 mg / kg) was also lower than that of Control Example 1 (0.14 mg / kg). This indicates that without the synergistic effect of step S2, root nutrient activation alone exacerbated fruit cracking due to accelerated fruit enlargement and weakened effective selenium accumulation, proving that step S2 plays an irreplaceable role in sweetening, crack prevention, and the synergistic effect of selenium metabolism. More importantly, compared with Control Example 1 (which only performed step S1), Control Example 4 showed significant improvements in fruit cracking rate, soluble solids, and selenium content. However, compared with Control Example 1, Control Example 5 showed an increased fruit cracking rate, decreased selenium content, and only a slight increase in soluble solids. This indicates that not every combination of two steps can produce a positive additive effect; the lack of integration with step S2 leads to the deterioration of some indicators. Control Example 2 demonstrates that without the foundational treatment of step S1, even with steps S2 and S3, the effect is almost ineffective.

[0083] The above results fully demonstrate that the three steps S1, S2, and S3 of the present invention are functionally interdependent and sequentially coordinated, forming an inseparable overall technical solution. The outstanding technical effect of combining selenium enrichment, high sweetness, and crack prevention cannot be achieved without any step or any combination of two steps.

[0084] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for simultaneously increasing selenium content and sweetness of Cucumis melo L. var. inermis Naud. cv. Charentais, comprising conventional cultivation management, characterized in that, It also includes the following steps: S1. On the day the female flower opens, spray composition A evenly onto the female flower. Composition A includes: sodium selenite, cysteine, methionine, and surfactant. S2. When the fruit develops to the size of an egg, spray the entire plant with composition B, which includes: methyl jasmonate, betaine, nano-silica-amino acid calcium complex, organoboron and spreading agent; the nano-silica-amino acid calcium complex is a mixture of nano-silica and amino acid calcium. S3. Apply composition C to the roots once each in the early and middle stages of fruit enlargement. Composition C includes: brown sugar, peanut bran, compound microbial agent and maifanite powder. The compound microbial agent contains Bacillus megaterium, Saccharomyces cerevisiae, and Lactobacillus plantarum, with an effective live bacteria count ≥200 million / mL.

2. The method for simultaneously increasing selenium content and sweetness of thick-skinned melon according to claim 1, characterized in that, In step S1, the composition and concentration of the composition A are as follows: sodium selenite 15-25 mg / L, cysteine ​​0.2-0.8 mmol / L, methionine 0.1-0.5 mmol / L, organosilicon surfactant 0.02%-0.1%, and the balance being water.

3. The method for simultaneously increasing selenium content and sweetness of thick-skinned melon according to claim 1, characterized in that, In step S2, the composition and concentration of the composition B are as follows: methyl jasmonate 5-20 mg / L, betaine 50-200 mg / L, nano silica-amino acid calcium complex 200-500 mg / L, organoboron 30-80 mg / L, developing agent 0.05%-0.2%, and the balance being water; in the nano silica-amino acid calcium complex, the mass ratio of nano silica to amino acid calcium is 1:2-1:

5.

4. The method for simultaneously increasing the selenium content and sweetness of thick-skinned melons according to claim 3, characterized in that, The preparation method of the nano-silica-amino acid calcium complex is as follows: nano-silica is dispersed in deionized water, and after being ultrasonically dispersed evenly, amino acid calcium solution is slowly added under stirring conditions, the mass ratio of nano-silica to amino acid calcium is controlled to be 1:2 to 1:5, the pH is adjusted to 6.0 to 7.0, and stirring is continued for 1 to 2 hours to obtain a stable complex suspension.

5. The method for simultaneously increasing the selenium content and sweetness of thick-skinned melons according to claim 1, characterized in that, In step S3, the dosage of composition C per mu is: 15-25 kg of brown sugar, 40-60 kg of peanut bran, 0.5-2.0 kg of compound microbial agent, and 5-10 kg of maifanite powder.

6. The method for simultaneously increasing the selenium content and sweetness of thick-skinned melons according to claim 1, characterized in that, The timing for step S2 is as follows: when more than 80% of the young fruits in the field have a diameter of 4-6 cm, spray the solution on a sunny afternoon after 4 pm. If it rains within 24 hours after spraying, you need to spray again.

7. The method for simultaneously increasing the selenium content and sweetness of thick-skinned melons according to claim 1, characterized in that, It also includes applying a foliar spray of Composition B once during the late stage of fruit enlargement to 7 days before maturity, in which the concentration of methyl jasmonate is 3-10 mg / L, the concentration of betaine is 30-100 mg / L, the concentration of nano-silica-amino acid calcium complex is 100-300 mg / L, and the concentration of organic boron is 20-50 mg / L, to strengthen the fruit peel skeleton.

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