Fertilizing method for promoting watermelon growth and improving quality based on sulfur element and application

Abstract

The invention belongs to the technical field of vegetable cultivation, and particularly relates to a sulfur-based fertilization method for promoting watermelon growth and improving quality and application. The fertilization method comprises the following steps: mixing peat, vermiculite and perlite according to a volume ratio of 3: 1: 1 to prepare a seedling culture substrate, adding sulfur powder, uniformly mixing, adjusting the water content to 55-65%, using the substrate as a base fertilizer, standing for 10 days, sowing watermelon seeds after germination acceleration, and carrying out seedling culture; when the watermelon seedlings grow to a one-leaf and one-core period, topdressing is started; the topdressing is a normal-sulfur Hoagland nutrient solution or a low-sulfur Hoagland nutrient solution, the topdressing is applied once every two days, the dosage of each time is 50 mL / plant, and the topdressing is continuously applied to the early stage of watermelon vine growing; and performing conventional pruning, pollination and fruit thinning management in and after the watermelon vine growing period until fruits are mature. The fertilizing method can promote plant growth, enhance oxidation resistance, and significantly improve watermelon fruit quality.

Description

Technical Field

[0001] This invention belongs to the field of vegetable cultivation technology, specifically relating to a fertilization method and application based on sulfur to promote watermelon growth and improve its quality. Background Technology

[0002] Watermelon, as a major summer fruit for cooling off, is highly nutritious and has a huge market demand. Its industrial development is of great significance to increasing agricultural income and extending the industrial chain.

[0003] Sulfur is an essential medium element for plant growth and development, second only to nitrogen, phosphorus, and potassium in importance. It participates in the synthesis of important compounds such as amino acids, proteins, and vitamins, and is crucial for plant photosynthesis, respiration, and metabolism. It also plays a key role in plant growth regulation, stress resistance, and quality improvement.

[0004] Existing research shows that the rational application of sulfur fertilizer can promote crop growth, increase yield and improve quality. However, there is a lack of clear conclusions on a specific sulfur element formula (including the type of sulfur source for base fertilizer, appropriate dosage and combination mode with topdressing) that can simultaneously meet the needs of robust seedling growth, optimized physiological functions and improved fruit quality in watermelon cultivation. This has led to problems such as blind application of sulfur fertilizer, unstable effects, waste of resources and environmental pollution in production.

[0005] Currently, sulfur fertilizer application in watermelon production often employs a single method, such as applying it only as a base fertilizer (e.g., sulfur or potassium sulfate) or only as a top dressing (e.g., foliar spraying of sulfate). These methods have significant drawbacks: applying sulfur only as a base fertilizer results in slow nutrient release, making it difficult to meet the sulfur requirements of watermelons during their vigorous vine growth and fruit enlargement stages, leading to nutrient gaps during critical growth periods and impacting yield formation; while relying solely on top dressing lacks long-term effectiveness and is prone to low utilization rates due to leaching, increasing production costs and environmental pollution risks; furthermore, excessive sulfur application can easily cause localized soil acidification, toxicizing the roots, inhibiting growth, and exacerbating soil-borne diseases. Therefore, there is an urgent need in agricultural production to develop a specialized sulfur element formula and application technology that can stably and efficiently supply sulfur nutrition, meet the growth and development needs of watermelons, and significantly improve watermelon yield and quality. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a fertilization method and application based on sulfur to promote watermelon growth and improve its quality. This method, through the scientific combination of base fertilizer sulfur and topdressing nutrient solution, precisely matches the sulfur nutrient requirements of watermelons at different growth stages, promoting plant growth, enhancing antioxidant capacity, and significantly improving fruit quality.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a fertilization method based on sulfur to promote watermelon growth and improve its quality, comprising the following steps: Mix peat, vermiculite, and perlite in a volume ratio of 3:1:1 to prepare a seedling substrate. Add sulfur powder and mix well. Adjust the moisture content to 55-65% as a base fertilizer. After 10 days, sow the pre-germinated watermelon seeds for seedling cultivation. Once the watermelon seedlings have grown to the stage of one leaf and one bud, topdressing should begin. The topdressing should be normal sulfur Hogland nutrient solution or low sulfur Hogland nutrient solution, applied every two days, with a dosage of 50 mL / plant each time, and continued until the early stage of watermelon vine emergence. During and after the watermelon vine-growing period, routine pruning, pollination, and fruit thinning are carried out until the fruit matures.

[0008] Furthermore, the amount of sulfur powder added is 0.5~4g per kg of seedling substrate.

[0009] Furthermore, the sulfur powder has a sulfur content of ≥98.5% by mass.

[0010] Furthermore, the watermelon seeds are the commercial variety "Zhemi No. 8".

[0011] Furthermore, the sowing process specifically involves sowing one pre-germinated watermelon seed for every 50g of base fertilizer.

[0012] Furthermore, the culture conditions are as follows: 8 h in darkness at 26 ℃, 16 h in light at 28 ℃, light intensity of 28000 Lux, and relative humidity of 60%RH.

[0013] The present invention also provides a fertilization method, comprising the following steps: Mix peat, vermiculite, and perlite in a volume ratio of 3:1:1 to prepare a seedling substrate. Add 1g of sulfur powder to each kg of seedling substrate, mix well, and adjust the moisture content to 60% as a base fertilizer. After 10 days, sow the germinated watermelon seeds for seedling cultivation. Once the watermelon seedlings have grown to the stage of one leaf and one bud, topdressing should begin. The topdressing is normal sulfur Hogland nutrient solution, applied every two days, with a dosage of 50 mL / plant each time, and continued until the early stage of watermelon vine emergence. During and after the watermelon vine-growing period, routine pruning, pollination, and fruit thinning are carried out until the fruit matures.

[0014] The present invention also provides an application of the above-mentioned fertilization method in watermelon plant cultivation.

[0015] This invention systematically measured and comprehensively evaluated the seedling growth indicators, physiological and biochemical characteristics, and fruit quality of 10 formulation combinations, and selected the optimal sulfur fertilization formula as "base fertilizer sulfur 1 g / kg substrate + normal sulfur Hogland nutrient solution top dressing".

[0016] The present invention has the following beneficial effects: (1) The base fertilizer sulfur provides a stable and long-lasting sulfur source. The water-soluble sulfate in the top dressing can quickly replenish the sulfur nutrition needed by the plant during the rapid growth stage, realizing the continuous and rapid synergistic supply of sulfur elements, adapting to the nutritional needs of watermelon growth stage, overcoming the disadvantages of slow or easy loss of sulfur element supply under a single fertilization method, and improving the utilization efficiency of sulfur fertilizer. (2) This formula can significantly enhance the photosynthetic efficiency, photosystem II function and antioxidant enzyme activity of watermelon seedlings, reduce oxidative damage, enhance the plant's stress resistance, and provide an internal guarantee for the healthy growth of seedlings; (3) It can effectively promote the accumulation of key quality components such as soluble solids, vitamin C and lycopene in the fruit, and achieve a significant improvement in the quality of watermelon fruit. (4) The appropriate amount of sulfur as the base fertilizer is precisely defined as 1 g / kg of substrate. When combined with normal sulfur Hogland nutrient solution for topdressing, the risks of local soil acidification, root poisoning, growth inhibition and aggravation of soil-borne diseases caused by excessive sulfur application can be avoided, thus achieving a dual balance between efficient sulfur nutrition supply and safe plant growth. Attached Figure Description

[0017] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] The following figures all use bar charts to show the differences in indicators among the various formulation combinations. The horizontal axis represents the sulfur concentration of the base fertilizer (g / kg), and the vertical axis represents the measured value of the corresponding indicator. Different fill patterns or colors represent normal sulfur topdressing and low sulfur topdressing treatments, respectively. Error bars represent standard deviations, and different lowercase letters in the charts indicate significant differences between treatments. P <0.05).

[0019] Figure 1 Phenotypic diagrams of watermelon seedlings treated with different sulfur element formulations.

[0020] Figure 2 Phenotypic images of watermelon fruits treated with different sulfur element formulations.

[0021] Figure 3 The following are bar charts showing the effects of different sulfur element formulations on the growth indicators of watermelon seedlings: (a) watermelon plant height, (b) watermelon stem diameter, (c) watermelon aboveground fresh weight, (d) watermelon aboveground dry weight, (e) watermelon underground fresh weight, and (f) watermelon underground dry weight.

[0022] Figure 4 The bar charts show the effects of different sulfur element formulations on chlorophyll content in watermelon seedlings. (a) is a bar chart of chlorophyll a content, (b) is a bar chart of chlorophyll b content, and (c) is a bar chart of total chlorophyll content.

[0023] Figure 5 The following are bar charts showing the effects of different sulfur element formulations on the photosynthetic parameters of watermelon seedlings: (a) is the bar chart of net photosynthetic rate A, (b) is the bar chart of intercellular CO2 concentration Ci, (c) is the bar chart of stomatal conductance gsw, and (d) is the bar chart of transpiration rate Emm.

[0024] Figure 6 The bar charts show the effects of different sulfur element formulations on the fluorescence parameters of watermelon chlorophyll. (a) is the bar chart of initial chlorophyll fluorescence Fo, (b) is the bar chart of maximum fluorescence Fm, and (c) is the bar chart of maximum photochemical quantum yield Fv / Fm of PSII.

[0025] Figure 7 The following are bar charts showing the effects of different sulfur element formulations on enzyme activity in watermelon leaves: (a) bar chart of superoxide dismutase activity, (b) bar chart of peroxidase activity, and (c) bar chart of catalase activity.

[0026] Figure 8 Bar charts showing the effects of different sulfur element formulations on the content of malondialdehyde (MDA), proline, soluble sugar, and total protein concentration in watermelon leaves are shown. (a) Bar chart of malondialdehyde content, (b) Bar chart of proline content, (c) Bar chart of soluble sugar content, and (d) Bar chart of total protein concentration in leaves.

[0027] Figure 9 The effects of different sulfur element formulations on the quality of watermelon fruit are shown in the following figures: (a) bar chart of watermelon transverse diameter, (b) bar chart of watermelon longitudinal diameter, (c) bar chart of watermelon center sugar content, (d) bar chart of watermelon edge sugar content, (e) bar chart of watermelon lycopene content, and (f) bar chart of watermelon vitamin C content. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto: Test materials: The sulfur tested contained ≥98.5% sulfur by mass (S) and was purchased from the Chinese herbal medicine processing plant of Huazhou Huayi Pharmaceutical Co., Ltd. The watermelon seeds used in the test were the commercial variety "Zhemi No. 8", purchased from Zhejiang Wuwangnong Seed Industry Co., Ltd., with a germination rate of ≥90%. Both normal-sulfur and low-sulfur Hogland nutrient solutions were purchased from Hunan Hogland Bioengineering Co., Ltd. The normal-sulfur Hogland nutrient solution used a standard Hogland complete nutrient formula with ample sulfur supply. The low-sulfur Hogland nutrient solution followed the standard formula, replacing the sole sulfur source, magnesium sulfate heptahydrate, with an equal amount of magnesium chloride, while keeping other components and concentrations unchanged to create low-sulfur stress conditions. The specific formula is as follows: Normal Hogland nutrient solution formula: Calcium nitrate tetrahydrate 945 mg / L, potassium nitrate 607 mg / L, ammonium dihydrogen phosphate 115 mg / L, magnesium sulfate heptahydrate 493 mg / L The concentrations are: 20 mg / L sodium ferric ethylenediaminetetraacetate, 2.86 mg / L boric acid, 2.13 mg / L manganese sulfate tetrahydrate, 0.22 mg / L zinc sulfate heptahydrate, 0.08 mg / L copper sulfate pentahydrate, and 0.02 mg / L ammonium molybdate, with a pH of 6.0.

[0029] Low-sulfur Hoagland nutrient solution formula: Calcium nitrate tetrahydrate 945 mg / L, potassium nitrate 607 mg / L, ammonium dihydrogen phosphate 115 mg / L, anhydrous magnesium chloride 191 mg / L, sodium iron ethylenediaminetetraacetate 20 mg / L, boric acid 2.86 mg / L, manganese sulfate tetrahydrate 2.13 mg / L, zinc sulfate heptahydrate 0.22 mg / L, copper sulfate pentahydrate 0.08 mg / L, ammonium molybdate 0.02 mg / L, pH=6.0.

[0030] Implementation steps: (1) Seed germination: Select watermelon seeds that are uniform in size, healthy and plump, put them in 55 ℃ warm water and stir quickly for 2 minutes, let them cool naturally and soak for 12 hours; spread the soaked seeds on a damp washcloth, wrap them and put them in a plastic bag, place them in a 31.5 ℃ constant temperature incubator to germinate, and wait for the seeds to sprout. (2) Preparation of cultivation substrate and application of base fertilizer: Mix peat, vermiculite, and perlite in a volume ratio of 3:1:1 to prepare the seedling substrate. Set up 5 sulfur base fertilizer gradient groups, namely control group S0 (no sulfur applied), gradient group S1 (sulfur application 0.5 g / kg substrate), S2 (sulfur application 1 g / kg substrate), S3 (sulfur application 2 g / kg substrate), and S4 (sulfur application 4 g / kg substrate). Mix the sulfur powder with the substrate thoroughly. Put 50 g of sulfur-containing substrate in each pot, adjust the moisture content to 60%, and sow after 10 days. Do not apply any other base fertilizer.

[0031] (3) Sowing and Environmental Management: Five gradients of sulfur dosage as base fertilizer and two types of topdressing nutrient solution were randomly combined to form 10 formulation combinations (as shown in Table 1). Each formulation combination had three biological replicates, with 10 pots per replicate, for a total of 300 pots. Germinated seeds were sown in the pots, one seed per pot, at a depth of 1-1.5 cm, and placed in an artificial climate chamber for cultivation. The environmental parameters were set as follows: 8 h darkness at 26 ℃, 16 h light at 28 ℃, light intensity of 28000 Lux, and relative humidity of 60%RH.

[0032] Table 1. 10 different sulfur element regulation treatment combinations (4) Topdressing: When the seedlings grow to the stage of one leaf and one bud, start to apply the corresponding type of nutrient solution. Apply once every two days, at a rate of 50 mL / plant. Continue to apply topdressing until the early stage of vine growth, then stop applying topdressing and conduct seedling index tests.

[0033] (5) Subsequent management: Pruning, pollination (artificial pollination, 9:00-11:00 am) and fruit thinning (leaving 1 fruit per plant) are carried out in accordance with conventional watermelon cultivation management methods until the fruit matures (about 35-40 days after pollination). During this period, environmental parameters are kept unchanged, and distilled water is added as needed.

[0034] (6) Determination of formula screening indicators: Seedling growth and physiological and biochemical indicators were uniformly sampled and measured in the early stage of vine growth (first true leaf); fruit quality indicators were sampled and measured in the fruit ripening period.

[0035] Example 1: Effects of different sulfur element formulations on growth indicators of watermelon seedlings Ten plants were randomly selected from each formulation combination to measure plant height (height from the base of the seedling to the growing point using a measuring tape), stem diameter (diameter 1 cm below the first node using a vernier caliper), aboveground fresh weight / dry weight (fresh weight after washing with distilled water and drying, followed by drying at 65 ℃ for 72 h to constant weight), and underground fresh weight / dry weight (same method as aboveground measurement).

[0036] The results show that ( Figure 3Under the same topdressing conditions, the plant height, stem diameter, aboveground and underground fresh weight, and dry weight of watermelon seedlings all showed a trend of first increasing and then decreasing with the increase of sulfur application in the base fertilizer. Furthermore, the normal sulfur topdressing group generally outperformed the low sulfur topdressing group in all indicators. Among them, the T3 formula combination (1 g / kg sulfur base fertilizer + normal sulfur topdressing) showed the best seedling growth, with plant height, stem diameter, aboveground dry weight, and underground dry weight increasing by 4.16%, 15.04%, 23.00%, and 10.09% respectively compared to the T1 formula combination (S0 + normal sulfur topdressing). In the low sulfur topdressing group, the T8 formula combination (1 g / kg substrate + low sulfur topdressing) showed relatively better growth, while the T6 formula combination (S0 + low sulfur topdressing) had the lowest indicators, indicating that insufficient sulfur supply led to stunted watermelon plants, yellowing leaves, and severely inhibited seedling growth. Figure 1 ).

[0037] Effects of different sulfur element formulations on the physiological and biochemical properties of watermelon seedlings The contents of chlorophyll a, chlorophyll b, and total chlorophyll were determined by ethanol extraction. Photosynthetic parameters (net photosynthetic rate A, intercellular CO2 concentration Ci, stomatal conductance gsw, and transpiration rate Emm) were measured using an L-6800 photosynthesis system. Chlorophyll fluorescence parameters (initial fluorescence Fo, maximum fluorescence Fm, and PSII maximum photochemical quantum yield Fv / Fm) were measured using a MINI-PAM-II modulation fluorescence instrument. The activities of superoxide dismutase (T-SOD), peroxidase (POD), and catalase (CAT) in leaves were determined using a kit method. The contents of malondialdehyde (MDA), proline, soluble sugar, and total protein concentration in leaves were determined by colorimetric methods.

[0038] Note: The reagent kit was purchased from Nanjing Jiancheng Biotechnology Institute. The operation was strictly performed in accordance with the kit instructions.

[0039] The results showed that ( Figure 4The T3 formula (1 g / kg basal sulfur + normal sulfur topdressing) showed the highest net photosynthetic rate (A), maximum PSII photochemical efficiency (Fv / Fm), and total chlorophyll content, significantly higher than other formula combinations. This indicates that the formula significantly enhanced the photosynthetic capacity and light energy utilization efficiency of the leaves. The low-sulfur topdressing treatment generally had lower photosynthetic parameters, suggesting that insufficient sulfur supply inhibits photosynthesis in watermelon seedlings. Regarding antioxidant and osmotic regulation, the T3 formula showed the highest activities of T-SOD, POD, and CAT, increasing by 46.06%, 36.59%, and 34.28% respectively compared to the T1 formula, while reducing MDA content by 8.38%. When sulfur was excessive, antioxidant enzyme activity decreased, MDA content increased, and the plants suffered oxidative damage. The low-sulfur topdressing group had higher MDA and proline content, with the T6 formula showing a 69.60% increase in proline content compared to the T3 formula. Furthermore, the total protein and soluble sugar content of leaves in the T3 formulation were increased by 14.42% and 53.15% respectively compared to the T1 formulation, while the total protein and soluble sugar content of leaves in the low-sulfur group were lower. Overall, the T3 formulation, by providing an appropriate level of sulfur nutrition, achieved a synergistic improvement in photosynthetic efficiency and stress resistance at the physiological and biochemical levels, providing an intrinsic guarantee for robust seedling growth.

[0040] Effects of different sulfur element formulations on watermelon fruit quality The watermelon was cut longitudinally, and the transverse diameter was measured at the widest point and the longitudinal diameter at the longest point using a measuring tape. The sugar content at the center of the fruit and at the edge about 1 cm from the peel were measured using a PAL-1 saccharimeter. The lycopene and vitamin C contents were determined using a kit method.

[0041] Note: The reagent kit was purchased from Nanjing Jiancheng Biotechnology Institute. The operation was strictly performed in accordance with the kit instructions.

[0042] The results showed that ( Figure 5 The sulfur-based fertilizer formulation has a significant impact on fruit quality. The T3 formulation (1 g / kg sulfur as base fertilizer + normal sulfur topdressing) showed the best performance in key quality indicators. Its central soluble solids content (sugar content) was the highest, significantly higher than the control and all other formulation combinations. Simultaneously, the vitamin C and lycopene content of the T3 formulation fruit were increased by 14.21% and 46.88% respectively compared to the T1 formulation control, indicating that this formulation effectively promotes the accumulation of sugar and functional nutrients in the fruit. In contrast, in the low-sulfur topdressing series, fruit sugar content and nutritional quality generally declined, with the T6 formulation combination showing the lowest levels of all fruit quality indicators. Figure 2 ).

[0043] Based on the data from Example 1 regarding seedling growth, physiological and biochemical aspects, and fruit quality, a systematic screening concluded that, under the conditions described in this invention, using a base fertilizer of 1 g / kg substrate, combined with a standard sulfur Hogrange nutrient solution for topdressing (i.e., the T3 formula combination), is the optimal sulfur fertilization formula that simultaneously promotes robust seedling growth, enhances plant physiological functions, and significantly improves watermelon fruit quality. In summary, the fertilization method and application obtained through systematic screening in this invention provide a dedicated sulfur nutrition solution for high-quality and efficient watermelon cultivation, featuring a clear formula composition, a scientific application process, and significant application effects.

[0044] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A fertilization method for promoting the growth and improving the quality of watermelon based on the element sulfur, characterized by, The method comprises the following steps: The peat, vermiculite and perlite are mixed in a volume ratio of 3:1:1 to prepare a seedling substrate, and sulfur powder is added and uniformly mixed to adjust the water content to 55-65%, which is used as basal fertilizer; after being placed for 10 days, the watermelon seeds after germination are sown to carry out seedling culture; When the watermelon seedlings grow to the one-leaf-one-heart stage, the topdressing is started to be applied; the topdressing is normal sulfur Hoagland nutrient solution or low-sulfur Hoagland nutrient solution, which is applied every two days, and the dosage is 50 mL / plant each time, and the application is continued until the watermelon vine-erecting stage; During the watermelon vine-erecting stage and after that, the conventional pruning, pollination and fruit thinning management are carried out until the fruit ripens.

2. The method of applying a fertilizer according to claim 1, wherein, The added amount of the sulfur powder is 0.5-4 g per kg of the seedling substrate.

3. The method of applying a fertilizer according to claim 1, wherein, The sulfur content of the sulfur powder is ≥98.5%.

4. The method of applying a fertilizer according to claim 1, wherein, The watermelon seeds are commercial seeds "Zhemih No. 8".

5. The method of applying a fertilizer of claim 1, wherein, The sowing is specifically: one watermelon seed after germination is sown per 50 g of the basal fertilizer.

6. The method of applying a fertilizer of claim 1, wherein, The culture conditions are: 8 h of dark environment, temperature of 26 ℃, 16 h of light environment, temperature of 28 ℃, light intensity of 28000 Lux, and air relative humidity of 60% RH.

7. The method of applying a fertilizer according to any one of claims 1 to 6, wherein, The method comprises the following steps: The peat, vermiculite and perlite are mixed in a volume ratio of 3:1:1 to prepare a seedling substrate, and 1 g of sulfur powder is added per kg of the seedling substrate, which is uniformly mixed to adjust the water content to 60%, which is used as basal fertilizer; after being placed for 10 days, the watermelon seeds after germination are sown to carry out seedling culture; When the watermelon seedlings grow to the one-leaf-one-heart stage, the topdressing is started to be applied; the topdressing is normal sulfur Hoagland nutrient solution, which is applied every two days, and the dosage is 50 mL / plant each time, and the application is continued until the watermelon vine-erecting stage; During the watermelon vine-erecting stage and after that, the conventional pruning, pollination and fruit thinning management are carried out until the fruit ripens.

8. Application of the fertilization method according to any one of claims 1-7 in watermelon plant cultivation.

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