A method for planting selenium-rich vegetables and application of the method

Abstract

The application belongs to the technical field of agriculture and specifically relates to a kind of selenium-rich fertilizer and a planting method and application of selenium-rich flowering cabbage, the selenium-rich fertilizer is made of nano selenium, trehalose, tea saponin and ammonium molybdate, after dilution, foliar spraying is carried out at the seedling stage, early and middle stage of flowering of flowering cabbage, and urea and potassium chloride are applied to the roots at the early stage of flowering, with the synergistic nutrition scheme of "high nitrogen, medium potassium and selenium supplementation", the total selenium content in the flowering cabbage is not less than 0.2 mg / kg, the proportion of organic selenium (mainly selenomethionine) is not less than 85%, and the content of vitamin C is 15-25% higher than that of the conventional selenium-rich method, so that the obtained product has better nutritional value and taste.

Description

Technical Field

[0001] This invention relates to the field of agricultural technology, and in particular to a method for cultivating and applying selenium-enriched fertilizer and selenium-enriched Chinese cabbage. Background Technology

[0002] Selenium is an essential trace element for the human body. Its core role is as a key component of glutathione peroxidase, one of the most important antioxidant enzymes in the body. It acts as the body's own "antioxidant guardian," scavenging harmful free radicals and protecting cells from oxidative damage, thus helping to delay aging and maintain cellular health. In addition to its powerful antioxidant function, selenium is also crucial for enhancing immunity and regulating thyroid function. It can increase the activity of immune cells, helping the body fight infection; it is also a component of key enzymes in the metabolism of thyroid hormones, ensuring the normal functioning of metabolism.

[0003] With increasing health awareness, the market demand for selenium-enriched agricultural products is growing. Animal offal, seafood, meat, and eggs are good sources of selenium in our daily diet. However, supplementing selenium through consuming products like selenium-enriched bok choy is safer and easier for the body to absorb and utilize, making it an ideal way to supplement selenium. Bok choy is a popular vegetable, and currently, common selenium-enriched cultivation methods involve applying sodium selenite to the soil or foliar spraying with selenate. However, these methods have several drawbacks: 1) Inorganic selenium (such as sodium selenite) is highly toxic, has a narrow application window, and can easily cause plant poisoning or soil pollution; 2) Selenium has low conversion efficiency within plants, and inorganic selenium is difficult to effectively convert into organic selenium forms (such as selenomethionine) that are more beneficial to human health; 3) Selenium fertilizer is easily washed away or fixed by rainwater, resulting in low bioavailability. Therefore, developing a high-efficiency, safe, and targeted selenium-enriched fertilizer and cultivation method for bok choy with high organic selenium content is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0004] Based on this, the present invention aims to overcome the shortcomings of the prior art and provide a selenium-enriched fertilizer formula and a method for planting selenium-enriched Chinese cabbage based on selenium-enriched fertilizer. This method significantly improves the enrichment efficiency and conversion rate of selenium in Chinese cabbage through precise application strategies, especially increasing the content of selenomethionine, while improving the overall nutritional quality of Chinese cabbage.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0006] A selenium-enriched fertilizer is made from the following raw materials in parts by weight: 4-6 parts nano-selenium, 50-150 parts trehalose, 5-25 parts tea saponin, and 2-4.5 parts ammonium molybdate.

[0007] Preferably, the particle size of the nano-selenium is 20-100 nm.

[0008] A method for cultivating selenium-enriched Chinese cabbage involves applying the aforementioned selenium-enriched fertilizer during the cultivation process.

[0009] Preferably, applying the selenium-enriched fertilizer includes:

[0010] The selenium-enriched fertilizer is diluted with water to obtain a selenium-enriched nutrient solution, which is then sprayed onto the leaves of Chinese cabbage. The selenium-enriched nutrient solution contains nano-selenium at a concentration of 80-120 mg / L (elemental selenium), trehalose at a concentration of 1.0-3.0 g / L, tea saponin at a concentration of 0.1-0.5 g / L, and ammonium molybdate at a concentration of 20-50 mg / L (elemental molybdenum).

[0011] Preferably, spraying the selenium-enriched nutrient solution onto the leaves of Chinese cabbage includes the following steps:

[0012] S10. When the Chinese cabbage seedlings have grown to the 3-4 leaf stage, apply the selenium-enriched nutrient solution as a foliar spray for the first time.

[0013] S20. When the Chinese cabbage enters the early stage of bolting, apply the selenium-enriched nutrient solution as a second foliar spray;

[0014] S30. When the Chinese cabbage enters the middle stage of bolting, apply the selenium-enriched nutrient solution as a third foliar spray.

[0015] Preferably, in step S20, urea and potassium chloride are applied to the roots in combination, with the amount of urea applied per mu being 5-10 kg and the amount of potassium chloride applied per mu being 3-5 kg.

[0016] Preferably, in steps S10-S30, the amount of selenium-enriched nutrient solution applied per mu (667 square meters) for three foliar sprays is 50-60L.

[0017] A selenium-enriched Chinese cabbage product, grown using the aforementioned method, wherein the total selenium content of the grown Chinese cabbage is not less than 0.2 mg / kg, and selenomethionine accounts for not less than 85% of the total selenium content.

[0018] Preferably, the vitamin C content of the planted Chinese cabbage is not less than 60mg / 100g.

[0019] The application of the aforementioned selenium-enriched fertilizer in increasing the total selenium content of agricultural products.

[0020] The present invention adopts the above technical solution, and its beneficial effects are as follows:

[0021] Using low-toxicity nano-selenium as the selenium source avoids the phytotoxicity risks of inorganic selenium. The total selenium content of the selenium-enriched bok choy produced by the method of this invention is not less than 0.2 mg / kg (meeting the selenium enrichment standard), of which organic selenium (mainly selenomethionine) accounts for more than 85%, which is significantly better than the method of simply spraying sodium selenite (the proportion of organic selenium is usually less than 70%). Its vitamin C content is 15-25% higher than that of products produced by conventional selenium enrichment methods, and its nutritional value and taste are better. Attached Figure Description

[0022] Figure 1 This is a comparison chart of the total selenium content in Chinese cabbage hearts during the first phase of the experiment.

[0023] Figure 2 This is a comparison chart of the proportion of organic selenium (mainly selenomethionine) in Chinese cabbage hearts during the first phase of the experiment.

[0024] Figure 3 This is a comparison chart of vitamin C content in Chinese cabbage from the first phase of the experiment.

[0025] Figure 4 This is a comparison chart of the total selenium content in Chinese cabbage hearts during the second phase of the experiment.

[0026] Figure 5 This is a comparison chart showing the proportion of organic selenium (mainly selenomethionine) in Chinese cabbage hearts during the second phase of the experiment.

[0027] Figure 6 This is a comparison chart of vitamin C content in Chinese cabbage from the second phase of the experiment. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this invention can be combined with each other. The technical solutions of this invention will be further described below in conjunction with the embodiments of this invention, and this invention is not limited to the specific implementation methods described below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not restrictive, as the scope of the invention is limited only by the appended claims and their equivalents. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. The technical solutions of the present invention will be further described below in conjunction with embodiments and accompanying drawings; however, the present invention is not limited to the following specific embodiments.

[0030] In one embodiment of the present invention, a selenium-enriched fertilizer is made from the following raw materials in parts by weight: 4-6 parts nano-selenium, 50-150 parts trehalose, 5-25 parts tea saponin, and 2-4.5 parts ammonium molybdate.

[0031] Nano selenium is elemental selenium (Se)0 Selenium is chemically very stable and non-oxidizing. As a "slow-release selenium source," it needs to be gradually oxidized and metabolized within cells to exert its biological effects. This slow release process avoids a sharp increase in intracellular selenium concentration, thus greatly reducing the plant's toxic stress response. Due to its low toxicity, plants are significantly more tolerant of it, allowing for the safe application of higher concentrations of selenium fertilizer, thereby achieving higher yields in total selenium content.

[0032] Traditional selenium-enriched planting methods mostly involve applying sodium selenite to the soil or spraying selenates on the leaves. The toxicity of sodium selenite stems from its active oxidizing properties (Se). 4+ It can directly produce reactive oxygen species in cells, leading to oxidative stress. At high concentrations, it has strong physiological toxicity to plants, inhibiting growth, causing leaf yellowing, and even death. This limits the safe concentration at which it can be applied, thus limiting the maximum enrichment potential of selenium.

[0033] Trehalose, a natural non-reducing disaccharide, significantly increases the total amount of selenium absorbed by reducing the surface tension of the solution, allowing nano-selenium to spread more evenly and adhere more firmly on the leaves.

[0034] Tea saponin, a natural nonionic surfactant, can reduce surface tension, enhance wetting and spreading, and improve the deposition and penetration of selenium. On the other hand, it can form complexes with selenium, reduce the biotoxicity of inorganic selenium, and exert a synergistic effect.

[0035] Ammonium molybdate, a micronutrient fertilizer, acts on the metabolic processes in plants, promoting the conversion of inorganic selenium into organic selenium (such as selenoproteins and selenoamino acids), significantly increasing the proportion of organic selenium, and improving the nutritional quality of selenium.

[0036] This application combines nano-selenium, trehalose, tea saponin, and ammonium molybdate, and the components produce an unexpected synergistic effect: trehalose not only stabilizes the nano-selenium system but also induces the plant's stress response and opens up absorption channels; tea saponin greatly improves the spread and adhesion of selenium-enriched nutrient solution on the waxy leaves of Chinese cabbage; and ammonium molybdate promotes the metabolism and transformation of nitrogen and selenium, achieving a "1+1+1>3" effect.

[0037] Furthermore, the particle size of the nano-selenium is 20-100 nm.

[0038] The method for cultivating selenium-enriched Chinese cabbage according to the present invention includes the following steps:

[0039] 1. Land preparation, ridging, and application of base fertilizer

[0040] Level the land, ensuring the height difference is no more than 5cm and the soil particles are no more than 3cm. Deep plow to a depth of 20cm-25cm and rotary till to a depth of 15cm-20cm. Apply base fertilizer in conjunction with rotary tillage, using 600kg-800kg of high-quality decomposed organic fertilizer, 60kg-80kg of oil cake, and 20-30kg of N, P, K compound fertilizer (N-P2O5-K2O ratio of 25-15-15) per mu. After the soil has been exposed to sunlight, create ridges with a ridge width of 1.2m-1.4m, a furrow width of 0.3m, and a ridge height of 20cm-25cm.

[0041] 2. Sowing

[0042] For open-field planting, choose suitable weather for sowing, and select high-quality, high-yield, adaptable, and disease-resistant varieties. For early spring cultivation, choose cold-resistant and bolt-resistant varieties such as March Green Cabbage Heart, and for summer and autumn cultivation, choose high-temperature resistant, moisture-resistant, and disease-resistant varieties such as Sijiu Cabbage Heart. Sow at a depth of 1cm-2cm, with a row spacing of 10cm-12cm and a plant spacing of 2cm-3cm. Sow 700g-1000g per mu. Immediately after sowing, spray water to soak the ridge surface and keep the soil moist.

[0043] 3 Field Management

[0044] 3.1 Thinning

[0045] Thinning should begin when the seedlings have 2 to 3 true leaves, with a spacing of 5-6 cm between seedlings. Remove small, diseased, and weak seedlings. After thinning, fertilize and water the roots promptly.

[0046] 3.2 Topdressing

[0047] 3.2.1 Apply topdressing fertilizer promptly after thinning, using 5 kg of water-soluble fertilizer (such as N-P2O5-K2O with a ratio of 15-15-15) per mu.

[0048] 3.2.2 Dissolve and dilute the selenium-enriched fertilizer to prepare a selenium-enriched nutrient solution. The concentration of nano-selenium in the selenium-enriched nutrient solution is 80-120 mg / L (calculated as elemental selenium), trehalose is 1.0-3.0 g / L, tea saponin is 0.1-0.5 g / L, and ammonium molybdate is 20-50 mg / L (calculated as elemental molybdenum).

[0049] 3.2.3 When the Chinese cabbage seedlings have grown to the 3-4 leaf stage, apply the selenium-enriched nutrient solution as a first foliar spray to the leaves of the Chinese cabbage.

[0050] 3.2.4 When the Chinese cabbage enters the early bolting stage, i.e. the budding stage, a second foliar spray of selenium-enriched nutrient solution should be carried out, combined with topdressing of urea and potassium chloride at the roots. The topdressing amount of urea is 5-10 kg per mu, and the topdressing amount of potassium chloride is 3-5 kg ​​per mu.

[0051] 3.2.5 When the Chinese cabbage enters the middle stage of bolting, apply a third foliar spray of selenium-enriched nutrient solution.

[0052] Each time, spray the selenium-enriched nutrient solution until both sides of the leaves are moist but not dripping. The amount sprayed per acre is 50-60L. Foliar spraying is best done after 16:00 in the afternoon. It is recommended that there is no rainfall within 24 hours after spraying and that the temperature is between 18-28℃. Three foliar sprays of selenium-enriched nutrient solution is the only selenium fertilizer application measure during the entire growth period of Chinese cabbage.

[0053] 3.2.6 Apply topdressing once or twice according to the growth period and growth conditions, with 5-10 kg of water-soluble fertilizer (such as N-P2O5-K2O ratio of 15-15-15) per mu.

[0054] 3.3 Water Management

[0055] Depending on the season, weather conditions, and soil moisture, spray water. During the seedling stage, spray water before 10 am or after 5 pm on sunny days, for 0.5 hours each time. During the vigorous seedling stage, spray water once every 2-3 days, for 10-15 minutes each time. Spray less or not at all on cloudy or rainy days. Before bolting (8-10 leaves), control watering for 2-3 days.

[0056] 4. Pest and disease control

[0057] 4.1 Major Diseases

[0058] Downy mildew, soft rot, anthracnose, gray mold, damping-off, etc.

[0059] 4.2 Major Insect Pests

[0060] Diamondback moth, cabbage caterpillar, aphid, flea beetle, American serpentine leafminer, whitefly, etc.

[0061] 4.3 Prevention and control methods

[0062] 4.3.1 Agricultural control

[0063] Select disease-resistant and high-quality varieties such as Sijiu Caixin, and implement reasonable crop rotation.

[0064] 4.3.2 Physical prevention and control

[0065] Hang yellow sticky traps (25cm×40cm), 30-40 traps per acre, and place 1 boat-shaped bait trap per acre.

[0066] One to two traps to kill pests.

[0067] 4.3.3 Biological control

[0068] Plant-derived pesticides such as matrine and biological pesticides such as neomycin are used to control pests and diseases.

[0069] 4.4.4 Chemical control

[0070] Select highly effective, low-toxicity, and low-residue pesticides, and strictly control the pesticide safety interval.

[0071] 5 Harvesting

[0072] 5.1 Harvesting Requirements

[0073] The optimal harvesting time is when the height of the flowering stalk is level with the top of the leaves, and the first flower has appeared at the tip. The best harvesting time is when the flower buds are open but not yet fully open, commonly known as "flowering at the top". Harvest when 2-3 leaves are left above the ground.

[0074] 5.2 Harvesting Methods

[0075] Harvest when there is no dew in the field, using stem cutting, with a stubble height of 3cm.

[0076] 6. Storage

[0077] After harvesting, the storage temperature of Chinese cabbage should be between 2℃ and 8℃, and the commercial storage and transportation temperature should be (2±1)℃.

[0078] A selenium-enriched Chinese cabbage product, grown using the aforementioned method, wherein the total selenium content of the grown Chinese cabbage is not less than 0.2 mg / kg, and selenomethionine accounts for not less than 85% of the total selenium content.

[0079] Furthermore, the vitamin C content of the cultivated Chinese cabbage is no less than 60mg / 100g.

[0080] The application of the aforementioned selenium-enriched fertilizer in increasing the total selenium content of agricultural products.

[0081] The technical solution and effects of the present invention will be further illustrated below through specific embodiments.

[0082] 1. Test site

[0083] The experimental zone is located in the vegetable planting base for supplying Hong Kong in Ligang Town, Helan County, Ningxia. Helan County is located inland and has a mid-latitude continental climate with four distinct seasons. The climate is dry, with cold winters and little snow, windy springs and autumns, low but concentrated rainfall, long hours of sunshine, abundant heat, large temperature differences, and many sunny days throughout the year with long hours of sunshine and high solar radiation.

[0084] 2. Test materials

[0085] The tested Chinese cabbage variety was the No. 49 Chinese cabbage from Guangdong Helinong Biological Seed Industry Co., Ltd.

[0086] Nano selenium: 99.9%, Jinhua Jiayuan Biotechnology Co., Ltd.;

[0087] Trehalose: Dezhou Huiyang Biotechnology Co., Ltd.;

[0088] Tea saponin: Xi'an Haoyu Kangze Biotechnology Co., Ltd.;

[0089] Ammonium molybdate tetrahydrate: 99%, Suzhou Dinghao Chemical Technology Co., Ltd.;

[0090] Anhydrous sodium selenite: 98%, Suzhou Dinghao Chemical Technology Co., Ltd.

[0091] Preparation of sodium selenite nutrient solution (concentration of 20 mg / L based on selenium element): Weigh 438 mg of anhydrous sodium selenite, add deionized water to a final volume of 10 L, and stir to dissolve.

[0092] Preparation of nano-selenium nutrient solution (concentration of 20 mg / L based on selenium element): Weigh 200 mg of nano-selenium, dilute with deionized water to 10 L, and stir to dissolve.

[0093] Preparation of nano-selenium nutrient solution (concentration of 60 mg / L based on selenium element): Weigh 600 mg of nano-selenium, dilute with deionized water to 10 L, and stir to dissolve.

[0094] Preparation of nano-selenium nutrient solution (concentration of 60mg / L selenium and 2.0g / L trehalose): Weigh 600mg of nano-selenium and 20g of trehalose, add deionized water to dilute to 10L, and stir to dissolve.

[0095] Preparation of nano-selenium nutrient solution (concentration of 60mg / L selenium and 0.3g / L tea saponin): Weigh 600mg of nano-selenium and 3g of tea saponin, add deionized water to dilute to 10L, and stir to dissolve.

[0096] Preparation of nano-selenium nutrient solution (concentration of 60 mg / L based on selenium element, concentration of 30 mg / L based on molybdenum element): Weigh 600 mg of nano-selenium and 553 mg of ammonium molybdate, add deionized water to dilute to 10 L, and stir to dissolve.

[0097] Preparation of selenium-enriched nutrient solution (concentration of 60 mg / L selenium, 2.0 g / L trehalose, 0.3 g / L tea saponin, and 30 mg / L ammonium molybdate): Weigh 600 mg of nano selenium, 20 g of trehalose, 3 g of tea saponin, and 553 mg of ammonium molybdate, mix them to make selenium-enriched fertilizer, dilute with deionized water to 10 L, and stir to dissolve.

[0098] 3. Testing methods and instruments

[0099] 3.1 Determination of total selenium content and organic selenium content

[0100] GB5009.93-2017 "National Food Safety Standard - Determination of Selenium in Food" and GB / T16631-2008 "National Food Safety Standard - Determination of Multiple Elements in Food" use inductively coupled plasma mass spectrometry for detection and analysis. All reagents involved in the detection method are commercially available analytical grade standard preparations.

[0101] 3.2 Determination of Vitamin C content

[0102] According to GB5009.86-2016 "National Food Safety Standard - Determination of Ascorbic Acid in Food", high performance liquid chromatography was used for detection and analysis. All reagents involved in the detection method were commercially available analytical grade standard preparations.

[0103] 3.3 Explanation of the Three Periods

[0104] When Chinese cabbage seedlings reach the 3-4 leaf stage: This is the seedling stage, which begins with the first true leaf (the first leaf that grows after the seed germinates) and continues until the fifth true leaf is fully unfolded. During this stage, the plant begins photosynthesis, independently absorbing nutrients, and begins flower bud differentiation.

[0105] Early bolting stage: also known as the budding stage, is the leaf growth period, which begins with the growth of the sixth true leaf and ends with the appearance of flower buds at the top of the plant. During this stage, vegetative growth is the main focus, and photosynthesis is vigorous, accumulating the material basis for subsequent bolting (i.e., the elongation of the flower stalk).

[0106] Mid-bolting stage: This refers to the period from the budding stage to when the flowering stalk reaches the commercial harvest standard. It is the flowering stalk formation stage, which begins when the plant begins to bud and ends when the flowering stalk reaches the commercial harvest standard. This is a stage where reproductive and vegetative growth proceed simultaneously. The flowering stalk elongates and thickens rapidly, and nutrients are quickly transported to the flowering stalk. This is a critical period for yield and quality formation.

[0107] 3.4 Sampling and testing method: Three sets of replicate products were randomly selected as samples, and each set was analyzed and measured. The average value of the three sets of samples was then taken as the test value.

[0108] 4. Experimental Design

[0109] 4.1 Phase I Trial

[0110] 4.1.1 Test Methods

[0111] The same plot of land was selected as the test group, and adjacent ridges were selected as the replication groups for the experiment. The ridge width was 1.2 meters, and each group was 1.2 × 3 meters. The experiment was set up with 8 groups, and each group had 3 replication groups.

[0112] The first phase of the experiment was conducted on April 10, 2025, with planting depth of 1 cm, row spacing of 10 cm, and plant spacing of 3 cm. Immediately after sowing, the soil surface was thoroughly watered to keep it moist. When the seedlings had two true leaves, thinning began, with a spacing of 6 cm between seedlings. Water-soluble fertilizer was applied promptly after thinning. The first foliar spray was applied when the seedlings reached the four-leaf stage. The second foliar spray was applied when the seedlings entered the early bolting stage, i.e., the budding stage. The third foliar spray was applied when the seedlings entered the middle bolting stage, with a spraying amount of 50 L per mu each time. Water-soluble fertilizer was applied twice according to the growth situation. During the seedling stage, water was sprayed before 10 am every day on sunny days for 0.5 hours each time. During the vigorous seedling stage, water was sprayed once every 2 days for 15 minutes each time. Water was withheld for 2 days before bolting.

[0113] Comparison with Example 1: No substance was sprayed;

[0114] Comparative Example 2: Three foliar sprays of sodium selenite nutrient solution, with a concentration of 20 mg / L based on selenium element;

[0115] Experimental Example 1: Three foliar sprays of nano-selenium nutrient solution were applied, with a concentration of 20 mg / L based on selenium element content;

[0116] Experimental Example 2: Three foliar sprays of nano-selenium nutrient solution were applied, with a concentration of 60 mg / L based on selenium element content;

[0117] Experimental Example 3: Three foliar sprays of nano-selenium nutrient solution were applied, with a selenium concentration of 60 mg / L and a trehalose concentration of 2.0 g / L.

[0118] Experimental Example 4: Three foliar sprays of nano-selenium nutrient solution were applied, with a concentration of 60 mg / L of selenium and 0.3 g / L of tea saponin.

[0119] Experimental Example 5: Three foliar sprays of nano-selenium nutrient solution were applied, with a selenium concentration of 60 mg / L and an ammonium molybdate concentration of 30 mg / L.

[0120] Experimental Example 6: Three foliar sprays were applied with selenium-enriched nutrient solution, with a concentration of 60 mg / L selenium, 2.0 g / L trehalose, 0.3 g / L tea saponin, and 30 mg / L ammonium molybdate.

[0121] 4.1.2 Test Results

[0122] See Table 1 and appendix Figure 1-3 .

[0123] Table 1 Comparison of data from the first phase of the experiment

[0124]

[0125] Analysis of experimental results:

[0126] (1) According to the experimental data of Comparative Example 2, sodium selenite has strong physiological toxicity at concentrations greater than 20 mg / L (based on selenium element concentration). It can inhibit the growth of Chinese cabbage, cause yellowing of leaves, and even death. This limits the safe concentration at which it can be applied, thereby limiting the maximum enrichment potential of selenium.

[0127] (2) According to the experimental data of Experiment 1-2, the planted Chinese cabbage was superior to the control in terms of selenium content, proportion of organic selenium (mainly selenomethionine), VC content, and morphology. The Chinese cabbage was rich in nutrients, of high quality, and free from yellowing leaves and other defects. The selenium content was significantly increased, and the Chinese cabbage showed significantly enhanced tolerance to nano-selenium. In a nano-selenium solution with a concentration of 60 mg / L (based on elemental selenium), the total selenium content of the Chinese cabbage was significantly higher than that of sodium selenite, reaching 0.14 mg / kg. The proportion of organic selenium (mainly selenomethionine) and VC content were also significantly increased. This indicates that using nano-selenium allows for the safe application of higher concentrations of selenium fertilizer, thereby achieving a higher yield in total selenium. Nano-selenium is elemental selenium (Se... 0 It is chemically very stable and does not have oxidizing properties. As a "slow-release selenium source", it needs to be gradually oxidized and metabolized in cells before it can exert its biological effects. This slow release process avoids a sharp increase in the concentration of selenium in cells, thereby greatly reducing the toxic stress response of plants.

[0128] (3) According to the experimental data of Experiment 3-6, when only trehalose was added to the nano-selenium, the total selenium content, the proportion of organic selenium (mainly selenomethionine), and the VC content of Chinese cabbage were all increased. When only tea saponin was added, the total selenium content increased slightly, while the proportion of organic selenium and the VC content remained unchanged. When only ammonium molybdate was added, the total selenium content remained unchanged, while the proportion of organic selenium and the VC content increased slightly. Trehalose, as a plant stimulant and stabilizer, greatly improved the spreadability and adhesion of the selenium-enriched nutrient solution on the waxy leaves of Chinese cabbage. It not only stabilized the nano-selenium system but also induced the plant's stress response and opened the absorption channels. Tea saponin, as a highly efficient surfactant and penetrant, improved the absorption effect. Ammonium molybdate, as an activator of key enzymes in selenium metabolism, is a component of nitrate reductase and selenite reductase, thus doubly promoting the metabolism and transformation of nitrogen and selenium. When nano-selenium, trehalose, tea saponin, and ammonium molybdate were combined and sprayed onto Chinese cabbage with a selenium-enriched nutrient solution containing 60 mg / L selenium, 2.0 g / L trehalose, 0.3 g / L tea saponin, and 30 mg / L ammonium molybdate, all indicators were significantly improved. The total selenium content reached 0.21 mg / kg, the proportion of organic selenium reached 83%, and the vitamin C content reached 63 mg / 100g, producing an unexpected synergistic effect.

[0129] 4.2 Second Phase Trial

[0130] 4.2.1 Test Methods

[0131] The second phase of the trial was conducted on July 10, 2025, with the same planting method as the first phase.

[0132] Preparation of selenium-enriched nutrient solution: Weigh out 800mg, 1000mg, 1200mg, and 1400mg of nano-selenium, respectively, and mix them with 20g of trehalose, 3g of tea saponin, and 553mg of ammonium molybdate to make selenium-enriched fertilizer. Dilute with deionized water to 10L, stir and dissolve to prepare selenium-enriched nutrient solutions with concentrations of 80mg / L, 100mg / L, 120mg / L, and 140mg / L (based on elemental selenium), 2.0g / L of trehalose, 0.3g / L of tea saponin, and 30mg / L of ammonium molybdate (based on elemental molybdenum).

[0133] The same plot of land was selected as the test group, and adjacent ridges were selected as the replication groups for the experiment. The ridge width was 1.2 meters, and each group was 1.2 × 3 meters. The experiment was set up with 7 groups, and each group had 3 replication groups.

[0134] Example 7: Three foliar sprays of selenium-enriched nutrient solution were applied, with a concentration of 80 mg / L selenium, 2.0 g / L trehalose, 0.3 g / L tea saponin, and 30 mg / L ammonium molybdate, with other parameters the same as in Example 6.

[0135] Experiment 8: Three foliar sprays of selenium-enriched nutrient solution were applied, with a concentration of 100 mg / L based on selenium element content. Other procedures were the same as in Experiment 7.

[0136] Experimental Example 9: Foliar spraying of selenium-enriched nutrient solution three times, with a concentration of 120 mg / L based on selenium element, and other procedures were the same as in Experimental Example 7;

[0137] Experimental Example 10: Three foliar sprays of selenium-enriched nutrient solution were applied, with a concentration of 140 mg / L based on selenium element content. Other aspects were the same as in Experimental Example 7.

[0138] Experimental Example 11: When Chinese cabbage enters the early stage of bolting, topdressing is applied to the roots on a sunny morning. Apply 8 kg of urea and 4 kg of potassium chloride per mu. Water after fertilization, and other procedures are the same as in Experimental Example 8.

[0139] Experiment 12: Three foliar sprays of selenium-enriched nutrient solution were applied, with a trehalose concentration of 1.0 g / L. Other procedures were the same as in Experiment 11.

[0140] Experiment 13: Three foliar sprays of selenium-enriched nutrient solution were applied, with a trehalose concentration of 3.0 g / L. Other procedures were the same as in Experiment 11.

[0141] 4.2.2 Test Results

[0142] See Table 2 and appendix Figure 4-6 .

[0143] Table 2 Comparison of data from the second phase of the experiment

[0144]

[0145] Analysis of experimental results:

[0146] (1) According to the experimental data of Experiment Examples 7-10, changing the foliar spraying concentration of nano-selenium in the selenium-enriched nutrient solution resulted in an increase followed by a decrease in the selenium content of Chinese cabbage as the spraying concentration increased, showing a certain dose-response effect. The optimal concentration of nano-selenium in the selenium-enriched nutrient solution was 100 mg / L, with a total selenium content of 0.26 mg / kg, an organic selenium content (mainly selenomethionine) of 87%, and a vitamin C content of 66 mg / 100g. When the concentration of nano-selenium in the selenium-enriched nutrient solution was 140 mg / L, the Chinese cabbage showed a slight toxic reaction.

[0147] (2) According to the experimental data of Experiment Example 11, the planting method of this application proposes a synergistic nutrition scheme of "high nitrogen-medium potassium-selenium supplementation". At the early stage of bolting, urea (high nitrogen) and potassium chloride (medium potassium) are applied as top dressing, and foliar spraying of selenium is carried out in combination. The enhanced nitrogen metabolism promotes the absorption and assimilation of selenium by plants. Potassium, as a "transport engine", significantly promotes the transport and redistribution of nano selenium from leaves to the heart of the plant, and has a certain synergistic effect. The two work together to significantly increase the total selenium content, the proportion of organic selenium (mainly selenomethionine) and vitamin C content, reaching 0.29 mg / kg, 89% and 70 mg / 100g, respectively.

[0148] (3) According to the experimental data of Experimental Examples 12-13, the concentration of trehalose showed a certain dose effect on the selenium content in Chinese cabbage. When the concentration of trehalose increased to the critical concentration, it formed a barrier, inhibited absorption, and reduced the efficiency of nano-selenium release, ultimately leading to a reduction in the effective selenium that the plant leaves could absorb.

[0149] In summary, this application provides a selenium-enriched fertilizer formula and a method for cultivating selenium-enriched Chinese cabbage based on the selenium-enriched fertilizer. This method significantly improves the enrichment efficiency and conversion rate of selenium in Chinese cabbage through precise application strategies, especially increasing the content of selenomethionine, while improving the overall nutritional quality of the Chinese cabbage. The total selenium content of the produced selenium-enriched Chinese cabbage is not less than 0.2 mg / kg, of which the proportion of organic selenium (mainly selenomethionine) is not less than 85%, which is significantly better than the scheme of simply spraying sodium selenite (the proportion of organic selenium is usually less than 70%). Its vitamin C content is 15-25% higher than that of products produced by conventional selenium enrichment methods, and its nutritional value and taste are better. This method solves the technical problems of inorganic selenium (such as sodium selenite) being highly toxic, having a narrow application window, and easily causing plant poisoning or soil pollution, and the difficulty in effectively converting inorganic selenium into an organic selenium form that is more beneficial to human health.

[0150] Obviously, the above embodiments and test examples of the present invention are merely illustrative examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A selenium-enriched fertilizer, characterized in that, It is made from the following raw materials in parts by weight: 4-6 parts nano selenium, 50-150 parts trehalose, 5-25 parts tea saponin, and 2-4.5 parts ammonium molybdate.

2. The selenium-enriched fertilizer according to claim 1, characterized in that, The nano-selenium has a particle size of 20-100 nm.

3. A method for cultivating selenium-enriched Chinese cabbage, characterized in that, Apply selenium-enriched fertilizer as described in any one of claims 1 to 2 during the cultivation of Chinese cabbage.

4. The method for cultivating selenium-enriched Chinese cabbage according to claim 3, characterized in that, Applying the selenium-enriched fertilizer includes: The selenium-enriched fertilizer was diluted with water to obtain a selenium-enriched nutrient solution, which was then sprayed onto the leaves of Chinese cabbage. The selenium-enriched nutrient solution contains nano-selenium at a concentration of 80-120 mg / L (based on elemental selenium), trehalose at a concentration of 1.0-3.0 g / L, tea saponin at a concentration of 0.1-0.5 g / L, and ammonium molybdate at a concentration of 20-50 mg / L (based on elemental molybdenum).

5. The method for cultivating selenium-enriched Chinese cabbage according to claim 4, characterized in that, Spraying the selenium-enriched nutrient solution onto the leaves of Chinese cabbage includes the following steps: S10. When the Chinese cabbage seedlings have grown to the 3-4 leaf stage, apply the selenium-enriched nutrient solution as a foliar spray for the first time. S20. When the Chinese cabbage enters the early stage of bolting, apply the selenium-enriched nutrient solution as a second foliar spray; S30. When the Chinese cabbage enters the middle stage of bolting, apply the selenium-enriched nutrient solution as a third foliar spray.

6. The method for cultivating selenium-enriched Chinese cabbage according to claim 5, characterized in that, In step S20, urea and potassium chloride are applied to the roots of the Chinese cabbage. The application rate of urea is 5-10 kg per mu, and the application rate of potassium chloride is 3-5 kg ​​per mu.

7. The method for cultivating selenium-enriched Chinese cabbage according to claim 5, characterized in that, In steps S10-S30, the amount of selenium-enriched nutrient solution applied per mu (667 square meters) is 50-60L for the three foliar sprays.

8. A selenium-enriched Chinese cabbage product, characterized in that, The selenium-enriched Chinese cabbage is grown using the cultivation method described in any one of claims 3 to 7, wherein the total selenium content of the grown Chinese cabbage is not less than 0.2 mg / kg, and the proportion of selenomethionine in the total selenium content is not less than 85%.

9. The selenium-enriched Chinese cabbage product according to claim 8, characterized in that, The vitamin C content of the cultivated Chinese cabbage is no less than 60mg / 100g.

10. The application of a selenium-enriched fertilizer as described in any one of claims 1 to 2 in increasing the total selenium content of agricultural products.

Images