A selenium-enriched millet foliar fertilizer for yellowing leaves, its preparation method and application

Abstract

This invention discloses a selenium-enriched foliar fertilizer for millet, its preparation method, and its application. This foliar fertilizer is specifically designed to increase the selenium content, yellow pigment content, and total flavonoid content of millet. Through reasonable experiments, a suitable fertilizer ratio for increasing the selenium and yellow pigment content of millet grains was determined. It can effectively increase the yellow pigment content and total flavonoid content of millet grains while ensuring selenium enrichment, and also guarantees no yield reduction. This has significant guiding value for improving the quality of selenium-enriched millet.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer technology, specifically relating to millet selenium-enriched yellowing foliar fertilizer, its preparation method, and its application. Background Technology

[0002] Selenium is an essential trace element for the healthy growth of humans and animals, participating in the normal functioning and metabolism of the body and playing a vital physiological role. Selenium deficiency directly leads to a decline in the body's immunity, resulting in various diseases such as Kashin-Beck disease, Keshan disease, and cardiovascular and cerebrovascular diseases. Therefore, appropriate selenium supplementation plays a positive role in improving human immunity, anti-oxidation, delaying aging, protecting and repairing damaged cells, preventing and fighting cancer, preventing and treating cardiovascular and cerebrovascular diseases, and reducing the toxicity of environmental pollutants. Selenium cannot be synthesized in the human body and can only be obtained through dietary intake. Food is the main source of selenium for the human body; therefore, developing selenium-enriched agricultural products is of great significance for ensuring daily selenium intake and safeguarding health.

[0003] my country is located in a selenium-deficient zone, with 72% of its land area classified as selenium-deficient or low-selenium, especially in northern regions where farmland soil selenium content is significantly low. Selenium deficiency is widespread among Chinese residents, with per capita selenium intake far below the recommended daily intake of 55.89 μg, and two-thirds of the country being selenium-deficient or low-selenium areas. To supplement selenium intake, research on selenium and the development of selenium-enriched agricultural products are receiving increasing attention. Millet (Setaria italica) is an ancient crop originating in China with a long history of cultivation and is one of the important grain crops in northern China. After hulling, millet is called foxtail millet. Producing selenium-enriched millet is of practical significance in meeting the daily nutritional needs of people in major producing areas and improving their nutritional structure.

[0004] Compared to wheat and rice, millet is not only rich in nutrients such as protein, fat, dietary fiber, and vitamins, but also contains abundant functional active ingredients, such as phenols, active peptides, and carotenoids, which have various health benefits, including lowering blood sugar, blood lipids, and blood pressure. Yellow pigments are an important nutrient in millet, and their chemical composition is basically the same as that of corn yellow pigments, mainly including zeaxanthin (3,3′-dihydroxy-β-carotene), cryptoxanthin (3-hydroxy-β-carotene), and lutein (3,3′-dihydroxy-α-carotene), belonging to natural carotenoids. Numerous studies and clinical trials at home and abroad have proven that natural carotenoids not only protect vision and epithelial cells, but also enhance human immunity, quench excess free radicals in the body, prevent and treat various cancers, and have good therapeutic effects on oral ulcers and skin diseases. Therefore, increasing the yellow pigment content of millet is beneficial to improving its health-promoting functions and should be an important direction for improving millet quality.

[0005] Total bioflavonoids refer to flavonoid compounds, a large class of natural products widely found in the plant kingdom. The most common in nature are flavones and flavonols, others include dihydroflavonols, isoflavones, biflavones, flavanols, chalcones, aurantium, anthocyanins, and neoflavonoids. Flavonoid compounds have anti-inflammatory, antiviral, choleretic, cardiotonic, sedative, and analgesic effects. They also possess antioxidant, anti-aging, immunomodulatory, and antitumor properties. Therefore, increasing the total flavonoid content in millet is a direction for improving its quality.

[0006] Chinese invention patent CN 112321350 A discloses "A high-efficiency foliar fertilizer for increasing millet yield with selenium enrichment and its preparation and application." The main purpose of this patent is to provide a high-efficiency foliar fertilizer for increasing millet yield with selenium enrichment that promotes selenium absorption by plants and increases millet yield. Therefore, its purpose is to increase the selenium content of millet and increase its yield, but it ignores the important indicators of millet, namely yellow pigment and total flavonoids. Therefore, this study takes Yunzhou District, Datong City, Shanxi Province as a pilot area to further enrich millet with selenium and increase the content of yellow pigment and total flavonoids in millet through foliar spraying fertilizer, thereby further improving the dietary and health care functions of millet. Summary of the Invention

[0007] The purpose of this invention is to provide a selenium-enriched foliar fertilizer for millet that can effectively increase the selenium content, yellow pigment content, and total flavonoid content of millet grains. This allows for further improvement of the yellow pigment and total flavonoid content of millet on the basis of achieving selenium enrichment, which is beneficial to enhancing the dietary and health benefits of millet.

[0008] To achieve the above objectives, the technical solution of the present invention is summarized as follows:

[0009] A selenium-enriched millet foliar fertilizer for yellowing the skin, wherein the foliar fertilizer is composed of the following raw materials in the following weight ratio: sodium selenite: potassium polyaspartate: chitosan oligosaccharide: humic acid = 130: 500: 100: 1000.

[0010] The preparation method of the above-mentioned millet selenium-enriched yellowing foliar fertilizer involves mixing sodium selenite, potassium polyaspartate, chitosan oligosaccharide, and humic acid in the stated proportions, dissolving them in water, and then diluting the solution to a certain ratio and bringing the volume to a fixed volume. A specific embodiment is as follows: 130g of sodium selenite, 500g of potassium polyaspartate, 100g of chitosan oligosaccharide, and 1000g of humic acid are mixed in the stated proportions, dissolved in water, and then diluted to 30L.

[0011] In practical use, the foliar fertilizer prepared according to the above method should be applied at a rate of 30 L / hm². 2 Spray the appropriate amount evenly onto the millet leaves. Preferably, the optimal spraying time is within 5 days after the start of the millet grain-filling stage. It is also important to choose a sunny, windless afternoon for spraying. If rainy weather occurs after spraying, re-spraying is necessary.

[0012] Another important objective of this invention is to provide the application of the aforementioned foliar fertilizer in increasing the selenium content, as well as the yellow pigment content and total flavonoid content of millet grains. To increase the yellow pigment and total flavonoid content of millet grains, the aforementioned foliar fertilizer can be sprayed according to the method of this invention. This effectively increases the content of functional substances in millet and improves its quality.

[0013] Advantages of this invention:

[0014] The foliar fertilizer of this invention is specifically designed to increase the selenium content, yellow pigment content, and total flavonoid content of millet. Through reasonable experiments, a suitable fertilizer ratio for increasing the selenium content and yellow pigment content of millet grains has been determined. It can effectively increase the yellow pigment content and total flavonoid content of millet grains while ensuring that the millet is selenium-rich, and it also ensures that the yield is not reduced. It has very important guiding value for improving the quality of selenium-rich millet. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, unless otherwise specified, the specific experimental methods involved in the following embodiments are conventional methods or implemented according to the conditions recommended in the manufacturer's instructions.

[0016] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the experimental methods in the following embodiments are all conventional methods. Unless otherwise specified, the reagents and materials used can be purchased commercially.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be used in this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0018] This study conducted a field trial in Yunzhou District, Datong City, Shanxi Province, located in northern Shanxi, to investigate the effects of this foliar fertilizer on millet yield and millet grain selenium content, yellow pigment content, total flavonoid content, and other indicators. The specific experimental process is as follows.

[0019] 1. Materials and Methods

[0020] 1.1 Overview of the Experimental Site

[0021] The experimental site was located at the Organic Dryland Farming Experimental Station of China Agricultural University, Yunzhou District, Datong City, Shanxi Province (39°88′N, 113°50′E). The soil type of the experimental site was loess-type cultivated land in the Loess Plateau region. Before the experiment, the total nitrogen, selenium content, available phosphorus, available potassium, organic matter content, and pH value of the soil were measured, as shown in Table 1. The soil selenium content was 0.12 mg / kg, which is considered low.

[0022] Table 1. Soil physicochemical properties at the test site

[0023]

[0024] 1.2 Test Materials

[0025] Test crop: Zhangza 13 millet

[0026] Foliar fertilizer composition: Sodium selenite; Potassium polyaspartate; Chitosan oligosaccharide; Humic acid

[0027] Instruments and Reagents: Electronic balance (MTQ-100, Shenzhen Mobil Electronics Co., Ltd.); Electric drying oven (YDL-2000, Shanghai Qigong Instrument Equipment Co., Ltd.); Germinated rice milling machine (JNPY-100, Shandong Yutai Jinli Grain and Oil Machinery Co., Ltd.); Universal grinder (DE-500, Wuyi Huacai Tools Co., Ltd.); Freeze dryer (SCIENTZ-18N, Ningbo Xinzhi Biotechnology Co., Ltd.); CNC ultrasonic cleaner (KQ-500DE, Kunshan Ultrasonic Instrument Co., Ltd.); Benchtop centrifuge (TG16-WS, Hunan Xiangyi Laboratory Instrument Development Co., Ltd.); Constant temperature water bath (DK-S26, Shanghai Jinghong Experimental Equipment Co., Ltd.); Automatic UV-Vis spectrophotometer (TU-1810plus, Shanghai Xipu Instrument Co., Ltd.); Millet thresher (Pintai Machinery Technology Co., Ltd.)

[0028] Concentrated nitric acid (superior grade, 65%-68%, Shanghai test); hydrogen peroxide solution (superior grade, 30%, Shanghai test); sodium borohydride (98%, Shanghai test); n-butanol (analytical grade, Shanghai test); β-carotene standard (Shanghai Jiuxinyan Biotechnology Co., Ltd.).

[0029] 1.3 Test Content

[0030] 1.3.1 Selection of Sodium Selenite Dosage

[0031] In 2021, a foliar spraying experiment with different dosages of sodium selenite was conducted at the Organic Dryland Farming Experimental Station of China Agricultural University in Yunzhou District, Datong City, Shanxi Province, to determine the optimal application rate. The millet variety used in this experiment was Jizhanggu No. 5. Different dosages of sodium selenite solution were sprayed onto the leaves during the millet's grain-filling stage (see Table 2). After the millet matured, it was harvested, and the yield, grain selenium content, yellow pigment content, and total flavonoid content were measured. According to the experimental results (see Table 3), the grain selenium content increased with increasing selenium application rate. However, at the I4 treatment (129.70 g / ha of sodium selenite), the millet yield, grain yellow pigment content, and total flavonoid content were all at relatively high levels. Therefore, 130 g / ha of sodium selenite is recommended as the most suitable dosage for exogenous selenium supplementation.

[0032] Table 2. Foliar spraying dosage of sodium selenite from millet in 2021

[0033]

[0034] Table 3. Millet yield, selenium content, yellow pigment content, and total flavonoid content in grains in 2021.

[0035]

[0036] 1.3.2 Determination of the test plan

[0037] The experiment was conducted at the Organic Dryland Farming Experimental Station of China Agricultural University in Datong City, Shanxi Province. Foliar spraying was performed once during the millet grain-filling stage. Specific experimental treatments are shown in Table 4. The compounding scheme involved mixing the above-mentioned spraying substances in certain amounts (see Table 5), and diluting with water to prepare a mixed solution before use. After the millet matured, it was harvested, and the selenium content, yellow pigment content, and total flavonoid content of the millet grains were measured.

[0038] Table 4. Field foliar spraying treatments for millet

[0039]

[0040] Note: L1 water usage is 30L / hm 2 The dosage of sodium L2 selenite is 130 g / hm. 2 When using L2 and L3, dilute with water to 30L / hm. 2 .

[0041] Table 5 Foliar Fertilizer (L3) Compound Formulation Scheme

[0042]

[0043] 1.4 Measurement Items and Methods

[0044] 1.4.1 Selenium content of millet grains

[0045] Several representative plants were selected at maturity, placed in kraft paper bags, and brought back to the laboratory. The ears were cut off, threshed using a threshing machine, and then dehulled twice using a germ rice milling machine to obtain millet. The millet samples were then crushed, passed through a 100-mesh sieve, and stored in resealable bags for the determination of selenium content in millet grains.

[0046] The determination of zinc content in plant organs should refer to GB5009.93-2017, and the specific operation method is as follows.

[0047] Accurately weigh 0.5000g of the powder sample and place it in a microwave digestion tube. Add 5mL of concentrated nitric acid and 2mL of 30% hydrogen peroxide. Cover with the inner cap, install the protective cover, and place the digestion vessel into the microwave digester. Set the microwave digestion program as follows:

[0048] Step 1: Power 600W, heating time 8min, temperature control 100℃, duration 5min

[0049] Step 2: Power 600W, heating time 8min, temperature control 150℃, duration 15min

[0050] Begin digesting the sample. After complete digestion, remove the inner container and continue heating on a hot plate at 170°C until approximately 1 mL of acid remains, being careful not to evaporate it to dryness. Add 5 mL of hydrochloric acid solution (6 mol / L) and continue heating until the solution becomes clear and colorless with the appearance of white fumes. Cool, wash the digested solution in the inner container with small amounts of water several times, and transfer it to a 10 mL volumetric flask. Add 2.5 mL of potassium ferricyanide solution (100 g / L), dilute to volume with water, and mix well before analysis. Determine the selenium content using an atomic fluorescence spectrophotometer. Perform a reagent blank determination simultaneously.

[0051] 1.4.2 Production

[0052] Millet was harvested at maturity. Two rows of five-meter-long millet with uniform growth were selected from each plot and harvested manually. The number of effective ears was calculated, and the millet was threshed using a small millet thresher and weighed. The yield was converted to 14% moisture content as the actual yield.

[0053] 1.4.3 Yellow pigment content

[0054] (1) Determination of yellow pigment content in samples

[0055] First, n-butanol and purified water are mixed evenly in a 1:1 volume ratio, and left to stand overnight to separate into layers, thus obtaining water-saturated n-butanol.

[0056] Select plump rice grains and grind them thoroughly into a fine powder using a grinder, then dry them using a freeze dryer. After drying, accurately weigh 0.4g of millet powder and place it in a 5mL brown centrifuge tube. Add 4mL of water-saturated n-butanol, tighten the cap, and place the tube on a reciprocating shaker to extract for 3 hours to ensure complete extraction of the yellow pigment.

[0057] After shaking, the sample was centrifuged at 4°C and 8000 rpm for 15 min, and then the supernatant was collected. The absorbance of the supernatant at 450 nm was measured using a UV spectrophotometer.

[0058] (2) Construction of the standard curve for yellow pigment

[0059] Weigh 20 mg of β-carotene standard sample and place it in a 200 mL volumetric flask. Add 4 mL of chloroform to dissolve it, and then add water-saturated n-butanol solution to the mark to prepare a 0.1 mg / mL β-carotene standard solution.

[0060] Then, 0, 100, 200, 300, 400, and 500 μL of β-carotene solution were respectively placed into 10 mL centrifuge tubes, and water-saturated n-butanol solution was added to make up to 10 mL, respectively, to obtain β-carotene standard solutions of 0 μg / mL, 1 μg / mL, 2 μg / mL, 3 μg / mL, 4 μg / mL, and 5 μg / mL. The absorbance of the β-carotene standard solutions at 450 nm was measured using a UV spectrophotometer to construct a standard curve.

[0061] 1.4.4 Total flavonoid content

[0062] Prepare the following reagents for later use: 60% ethanol, 10% aluminum nitrate solution, 1 mol / L sodium hydroxide solution, and 5% sodium nitrite solution;

[0063] Weigh 0.8g of rice flour and transfer it to the bottom of a 10mL capped centrifuge tube. Transfer 8mL of ethanol solution to the tube. Transfer the capped centrifuge tube to an ultrasonic cleaner and centrifuge for 40 minutes at 60℃ and 300W. After centrifugation, transfer the tube to a high-speed centrifuge and centrifuge for 10 minutes at 8000r / min. Transfer 3mL of the extract to another 10mL unused centrifuge tube. Add 4.4mL of ethanol solution and 0.3mL of sodium nitrite solution in sequence, mix well, and wait for 6 minutes. Then add 0.3mL of aluminum nitrate solution, mix thoroughly, and wait for 6 minutes. Gently add 2mL of sodium hydroxide solution, shake well, wait for 15 minutes, and measure the absorbance at 510nm to calculate the total flavonoid content of the millet.

[0064] 1.5 Data Analysis

[0065] Data were statistically analyzed using Excel 2023, and R 4.3.0 was used for data analysis and plotting. The LSD test was used for analysis of variance between groups, and p < 0.05 was considered statistically significant.

[0066] 2 Results and Analysis

[0067] 2.1 Effects of foliar fertilizer application on millet yield and quality indicators

[0068] Table 6 Millet Yield and Quality Indicators

[0069]

[0070] Note: Millet refers to the commercial millet obtained after removing the husk, while husk refers to unhusked millet.

[0071] As shown in Table 6, compared with the L1 (control) treatment, the yields of both the L2 and L3 treatments were increased. However, the differences in millet yield among the treatments were not statistically significant. This indicates that spraying this foliar fertilizer can ensure that the millet yield does not decrease.

[0072] Regarding the selenium content in millet grains, the L3 treatment had the highest selenium content, reaching 0.512 mg / kg. The selenium content in the grains was significantly increased, 11.7 times higher than the control L1 and 21.9% higher than the selenium-only treatment L2.

[0073] Regarding the content of yellow pigment in the grains, the L3 treatment had the highest content of yellow pigment, reaching 59.34 mg / kg, which was significantly higher than other experimental treatments. Compared with the control L1, it increased by 6.4%, and compared with the selenium-only treatment L2, it increased by 3.4%.

[0074] In terms of total flavonoid content in the seeds, the L3 treatment had the highest total flavonoid content, reaching 151.89 mg / 100g, which was significantly higher than other experimental treatments. Compared with the control L1, it increased by 39.5%, and compared with the selenium-only treatment L2, it increased by 7.6%.

[0075] The embodiments described above are merely preferred embodiments of the present invention and are only used to explain the present invention. They are not intended to limit the scope of the present invention. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. The application of a selenium-enriched foliar fertilizer for millet in increasing the selenium content, yellow pigment content, and total flavonoid content of millet grains, characterized in that... The foliar fertilizer is composed of the following raw materials in the following weight ratio: sodium selenite: potassium polyaspartate: chitosan oligosaccharide: humic acid = 130:500:100:1000. Sodium selenite, potassium polyaspartate, chitosan oligosaccharide and humic acid are mixed in the above ratio, dissolved in water, and then diluted to a certain multiple and brought to a fixed volume. The prepared foliar fertilizer is sprayed evenly on the leaves of millet at a rate of 30 L / hm² within 5 days after the start of the millet grain-filling period.

2. The application according to claim 1, characterized in that, Mix 130 g sodium selenite, 500 g potassium polyaspartate, 100 g chitosan oligosaccharide, and 1000 g humic acid in the proportions described above, dissolve in water, and then dilute to 30 L.

3. The application according to claim 1, characterized in that, Choose to spray on a sunny, windless afternoon. If it rains after spraying, you must spray again.

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