Application of selenium-rich foliar fertilizer in improving nutrient content of rice

Abstract

The invention discloses an application of a selenium-rich foliar fertilizer in improving the nutrient content of paddy rice, which is characterized in that sodium selenite, organic selenium (selenomethionine, SeMet) and biological nano-selenium are mixed according to a proper proportion, and the mixture is sprayed to the paddy rice in a proper period, so that the nutrient content of the paddy rice is increased, and the nutrient content of the paddy rice is increased. Results show that the mixed selenium fertilizer not only can promote selenium absorption of plants, but also improves the content of selenium methylcysteine (MeSeCys) and resistant starch in brown rice, improves the production benefit of rice and the dietary therapy nutrition and health care function of rice besides staple food, ensures that the yield is not reduced, and is suitable for large-scale production. The method has a very important guiding value for improving the quality of the selenium-enriched rice.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizer application, and particularly relates to the application of selenium-enriched foliar fertilizer in improving the nutrient content of rice. Background Art

[0002] Selenium is an essential trace element for the healthy growth of humans and animals. It participates in the normal operation and metabolism of human and animal bodies and has important physiological functions. Selenium deficiency directly leads to a decline in human immunity and the occurrence of various diseases, such as osteomalacia, Keshan disease, cardiovascular and cerebrovascular diseases, etc. Therefore, appropriate selenium supplementation has a positive effect on 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 ensured through the intake of external food to ensure the physiological activities of the body. Food is the main channel for human selenium supplementation. The development of selenium-rich agricultural products is of great significance to ensure the daily selenium intake of the human body and to ensure good health. Plant organic selenium sources are far better than inorganic selenium sources on the human body, especially selenomethylcysteine ​​(MeSeCys) in organic selenium has strong anti-cancer properties, which is of great significance for human selenium supplementation. Rice starch contains a component of insoluble dietary fiber, namely resistant starch (RS). Rice rich in RS can not only effectively lower the glycemic index, increase satiety, and prevent blood sugar-related diseases, but also prevent intestinal-related diseases by improving the intestinal microenvironment and lowering colon pH.

[0003] my country is located in the world's selenium-deficient belt, with 72% of the country being selenium-deficient or low-selenium areas, especially in the northern region where the selenium content of farmland soil is significantly low. Selenium deficiency is most common among Chinese residents, with the domestic per capita selenium intake far below the recommended daily intake of 55.89 μg, and 2 / 3 of the regions are selenium-deficient or low-selenium areas. In order to supplement the intake of selenium, people are paying more and more attention to the research on selenium and the development of selenium-rich agricultural products. In particular, with the improvement of people's living standards, the demand for foods with specific functional ingredients is increasing. Rice (Oryza sativa L) is my country's largest food crop. The production of selenium-enriched rice and increasing the content of its functional nutrients are of practical significance for meeting people's daily nutritional needs, improving nutritional structure and improving health levels.

[0004] Rice crops are the staple food of most people. They not only provide the energy substances such as starch and sugar that the human body needs, but are also rich in dietary fiber, vitamins and functional active ingredients, such as specific organic selenium and resistant starch, which have multiple health functions such as lowering blood sugar, lowering blood lipids and lowering blood pressure. Among them, selenomethylcysteine ​​(MeSeCys) is an extremely important nutrient. A large number of studies and clinical trials at home and abroad have shown that organic selenium can improve human immunity, quench excessive free radicals in the body, prevent and treat various cancers, and have a good effect on oral ulcers, skin diseases, etc. Therefore, increasing the content of organic selenium and resistant starch in rice is conducive to improving the therapeutic health function of rice, and should be regarded as an important direction for improving the quality and efficiency of rice production and improving rice quality.

[0005] The development of selenium-rich agricultural products has been widely used in production practice, but there is little research on the development of rice products with specific functional ingredients. The supply market of these selenium-rich and functionally nutritious rice will greatly enrich and improve people's quality of life, making food consumption with antioxidant, anti-aging, immune regulation and anti-tumor effects a popular demand. Therefore, increasing the content of specific organic selenium and resistant starch in rice is an important part of improving its quality. Summary of the invention

[0006] The purpose of the present invention is to provide a method for increasing the nutrient content in rice by spraying selenium-rich foliar fertilizer on the rice leaves.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] First, a selenium-rich foliar fertilizer is prepared. The selenium-rich foliar fertilizer is composed of the following raw materials in the following weight ratio: sodium selenite, selenomethionine (SeMet) and bio-nanoselenium in a ratio of 1200:300:0.1. The sodium selenite, selenomethionine and bio-nanoselenium are mixed evenly according to the above weight ratio and dissolved in water. 150.3g of the mixed selenium solution is diluted to 60L. When used, 30L / hm2 is used each time. 2 Spray the amount of the product evenly on the rice leaves twice. The spraying period is from the tillering stage to the grain filling stage, and the best spraying period is within 5-10 days after the rice grain filling stage begins. And pay attention to spraying in the afternoon when it is sunny and windless. If it rains after spraying, you must spray again.

[0009] The most important invention point of the present invention is that the selenium content of rice, the organic selenium (selenomethylcysteine, MeSeCys) content of brown rice, and the resistant starch content, especially the resistant starch content, are increased by spraying the above-mentioned foliar fertilizer. Therefore, from another aspect, the present invention provides a method for increasing the content of selenomethylcysteine ​​and resistant starch in rice, by spraying the above-mentioned selenium-rich foliar fertilizer from the booting stage to the filling stage of rice. Spraying the above-mentioned foliar fertilizer according to the method of the present invention can effectively increase the content of functional nutrients in rice and improve its quality.

[0010] In addition, the above experiments also allow us to draw the following conclusions: the above selenium-rich foliar fertilizer has the effect of increasing the nutrient content of rice, which also provides a new efficacy of the above foliar fertilizer, especially in increasing the content of selenomethylcysteine ​​(MeSeCys) and resistant starch in brown rice, which has not been reported before.

[0011] Advantages of the present invention:

[0012] The present invention adopts sodium selenite, selenomethionine and biological nano-selenium, three kinds of selenium are mixed in a suitable proportion, and the mixture is sprayed on rice at a suitable period. The result shows that the mixed selenium fertilizer can not only promote the absorption of selenium by plants, but also increase the content of selenomethylcysteine ​​(MeSeCys) and resistant starch in brown rice, thereby improving the production efficiency of rice and the therapeutic nutritional health function of rice other than staple food, and ensuring that the output does not decrease, which has very important guiding value for improving the quality of selenium-enriched rice. DETAILED DESCRIPTION

[0013] The present invention will be further described below in conjunction with specific examples, and the advantages and features of the present invention will become clearer as the description proceeds. However, the specific experimental methods involved in the following examples are all conventional methods or implemented under the conditions recommended by the manufacturer's instructions unless otherwise specified.

[0014] Unless otherwise specified, the technical means used in the examples are conventional means known to those skilled in the art. The test methods in the following examples are conventional methods unless otherwise specified. Unless otherwise specified, the reagents and materials used can all be purchased from the market.

[0015] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only.

[0016] This study conducted a field trial in Guangshan County, Xinyang City, Henan Province, which is located in the Huanghuai region of my country, to investigate the effects of the selenium fertilizer on rice yield and the selenium content and functional component content of brown rice. The specific experimental process is as follows.

[0017] 1 Materials and methods

[0018] 1.1 Overview of the test site

[0019] The test site was Lilou Village, Guangshan County, Xinyang City, Henan Province (112°58'-113°30'N, 27°54′-28°22′E). The soil in the test site was brown red paddy soil. Before the test, the total nitrogen, soil 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 0.43 mg / kg, which was a low selenium level.

[0020] Table 1 Physical and chemical properties of soil in the test site

[0021]

[0022] 1.2 Test materials

[0023] Tested crops: The tested rice (Oryza sativa L.) variety is 'Taoxiang Youzhan', the parents are Xuan 69S (♀) × WH 26, a three-line indica hybrid rice variety approved by the state in 2007 (No.: Guoshendao 20210307). It is planted as wheat stubble rice in the middle and lower reaches of the Yangtze River, with a full growth period of 125 days.

[0024] Selenium fertilizer composition: sodium selenite (analytical grade), purchased from Nanjing Chemical Reagent Co., Ltd.; selenomethionine (analytical grade), purchased from Nanjing Chemical Reagent Co., Ltd.;

[0025] Bio-nanoselenium: It is a patented product of China Agricultural University. Bio-nanoselenium (NS) was kindly donated by Professor Pan Canping of China Agricultural University (using selenite as raw material and synthesized by microbial fermentation). The particle size of nano-selenium is 25-60nm. It is a purple-red powder and is easily soluble in water. (See: A Chinese invention patent: Pan Canping. Chitosan functionalized nano-selenium compatible bacterial enzyme system and its preparation method and application. Chinese patent ZL 2015 1 0698215.X, 2019-11-1; published papers: Li, D.; Zhou, CR; Zou, N.; Wu, YL.; Li, JQ; Pan, CP Nanoselenium foliar application enhances biosynthesis of tea leaves in metabolic cycles and associated responsive pathways. Environ. Pollut. 2021, 273, 116503.)

[0026] Instruments and reagents: electronic balance (MTQ-100, Shenzhen Meifu Electronics Co., Ltd.); electric blast drying oven (YDL-2000, Shanghai Qigong Instrument Equipment Co., Ltd.); germ rice machine (JNPY-100, Shandong Yutai Jinli Grain and Oil Machinery Co., Ltd.); universal crusher (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.); desktop centrifuge (TG16-WS, Hunan Xiangyi Laboratory Instrument Development Co., Ltd.); constant temperature water bath (DK-S26, Shanghai Jinghong Experimental Equipment Co., Ltd.); automatic UV-visible spectrophotometer (TU-1810plus, Shanghai Xipu Instrument Co., Ltd.); rice thresher (Pintai Machinery Technology Co., Ltd.)

[0027] 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).

[0028] 1.3 Test content

[0029] 1.3.1 Selection of dosage of mixed selenium solution

[0030] In 2021, at the regenerated rice experimental station of Henan Agricultural University in Lilou Village, Guangshan County, Xinyang City, Henan Province, experiments were conducted on the effects of different amounts of selenium mixtures and different spraying periods to determine the optimal spraying period and amount. The rice variety in this experiment was Taoxiang Youzhan, and the experimental treatment was to spray different amounts of selenium fertilizer solution on the leaves during the rice heading period (see Table 2). The rice was harvested after maturity, and the total yield and rice yield were measured respectively. According to the experimental results, with the increase of different selenium sources, the total biomass of rice and the brown rice yield continued to increase, but in the C123 treatment combination, i.e. 120g sodium selenite, 30g selenomethionine, and 30mg bio-nanoselenium, the yield and total biomass of rice were at a relatively high level, so the C123 combination was selected, i.e. 150.03g / hm 2 The selenium mixture mainly composed of sodium selenite is the most suitable amount for exogenous addition of selenium.

[0031] Table 2 Effects of spraying different selenium solution ratios at the booting stage on rice biomass and yield in 2021

[0032]

[0033] 1.3.2 Determination of the experimental plan

[0034] The test site is located at the Henan Agricultural University Regeneration Rice Experiment Station in Lilou Village, Guangshan County, Xinyang City, Henan Province. The rice was sprayed on the leaves twice during the heading stage. The specific test treatments are shown in Table 2. Based on the previous year's test, the C23 combination with the worst effect was eliminated in the 2022 field test, and water was added to make a mixed solution when used. Three periods of rice development were selected for the test to determine the most critical application period and the optimal concentration of mixed selenium solution. The treatment combinations are shown in Table 3. The rice was harvested after maturity, and the selenium content, organic selenium (selenomethylcysteine) content and resistant starch content of the rice brown rice were determined respectively.

[0035] 1.4 Measurement items and methods

[0036] 1.4.1 Selenium content in brown rice

[0037] Several representative plants were selected at maturity, placed in kraft paper bags, taken back to the laboratory, and the ears were cut off, then threshed with a thresher, and then husked twice with a germ rice machine to obtain rice. The rice samples were then crushed and passed through a 100-mesh sieve and stored in a ziplock bag for the determination of selenium content in brown rice.

[0038] Table 3 Effects of foliar fertilizer spraying at different rice growing stages on rice yield and quality in 2022

[0039]

[0040]

[0041] The determination of selenium content in plant organs refers to GB5009.93-2017, and the specific operation method is as follows.

[0042] Accurately weigh 0.5000g of powder sample, place it in a microwave digestion tube, add 5mL of concentrated nitric acid and 2mL of 30% hydrogen peroxide, cover the inner cover, install the protective cover, place the digestion tank in the microwave digestion instrument, and set the microwave digestion program as follows:

[0043] Step 1: Power 600W, heating time 8min, control temperature 100℃, duration 5min

[0044] Step 2: Power 600W, heating time 8min, control temperature 150℃, duration 15min

[0045] Start digesting the sample. After the digestion is complete, take out the inner tank and continue to add acid on the hot plate at 170°C until the volume is about 1mL. Do not evaporate to dryness. Add 5mL of hydrochloric acid solution (6mol / L) and continue heating until the solution becomes clear and colorless with white smoke. Cool it, wash the digestion solution in the inner tank with water in small amounts several times and transfer it to a 10ml volumetric flask, add 2.5mL of potassium ferrocyanide solution (100g / L), make up to volume with water, and mix well for testing. Use an atomic fluorescence spectrophotometer to determine the content of selenium. Perform a reagent blank determination at the same time.

[0046] 1.4.2 Output

[0047] Rice was harvested at maturity. Uniformly growing rice plants were selected from each experimental plot for manual harvesting. The plant weight was weighed to calculate the biomass, and the number of effective ears was counted. The rice was threshed using a small rice thresher and then weighed, and the actual yield was calculated based on a moisture content of 14%.

[0048] 1.4.3 Determination of organic selenium content

[0049] (1) Instruments and main reagents

[0050] Liquid chromatography-quadrupole / electrostatic field orbitrap high-resolution mass spectrometry system (LC-Q Exactive Orbitrap MS, ThermoFisher, USA); electronic balance (Sartorius, Germany); centrifuge (Hitachi, Japan); 5510-E ultrasonic cleaner (Branson, USA).

[0051] Selenomethycysteine ​​(MeSeCys, purity 98%, Beijing Bailingwei Company); lipase and amylase (analytical grade, Beijing Solebow Technology Co., Ltd.); proteinase K and proteinase XIV [Tiangen Biochemical Technology (Beijing) Co., Ltd.]; methanol and acetonitrile (chromatographic grade, JTBaker Company, USA); formic acid (chromatographic grade, Fluka Company, Germany); Milli-Q water: prepared by Millipore water purifier.

[0052] (2) Determination of organic selenium content: 0.5 g of sample was accurately weighed using a four-position balance and placed in a centrifuge tube (15 mL) as a reagent blank. 5 mL of ultrapure water and 20 mg of protease XIV were added, vortexed for 30 s to mix, and ultrasonicated in a 37°C water bath for 1.5 h. After ultrasonication, the sample was transferred to a centrifuge for centrifugation at a speed of 6000 r / min for 10 min. After standing, the supernatant was filtered through a 0.22 μm filter membrane and measured on the machine. The main instrument parameters of the Q-Exactive gas analyzer are shown in Table 4.

[0053] (3) HPLC conditions: Waters Symmetry RP18 liquid chromatography column (3.9 mm × 150 mm, 5 μm); injection volume 3 μL; column temperature 20°C; mobile phase: A water, B acetonitrile, flow rate 0.3 mL / min, gradient elution program as shown in Appendix 1. Mass spectrometry conditions: heated electrospray ion source (HESI); spray voltage 3.0 kV; capillary temperature 350°C; heater temperature 300°C; scan mode is Full MS / dd-MS2; mass spectrometry scan range m / z 50-500; the first-level full scan (Full MS) resolution is 70000, the C-trap maximum capacity (AGC target) is 3×106, and the C-trap maximum injection time is 200 ms; the data-dependent secondary product ion scan (dd-MS2) resolution is 17500, the C-trap maximum capacity (AGC target) is 1×105, the C-trap maximum injection time is 50 ms, and the collision energy (CE) of the secondary mass spectrometry is 30 eV; the sheath gas pressure is 35 arb; the auxiliary gas pressure is 10 arb.

[0054] Table 4 Gradient elution program

[0055]

[0056] 1.4.4 Resistant starch content

[0057] (1) Main reagents

[0058] Pancreatic alpha-amylase, amyloglucosidase, methylated spirit (IMS), sodium acetate.

[0059] (2) Measurement process

[0060] Weigh 100 mg of sample accurately, add 4 mL of pancreatic α-amylase and AMG mixture (pH 6.0), shake in a water bath at 37°C for 16 h, take out and add 4.5 mL of industrial methylated alcohol (IMS) and centrifuge (3000 r / min, 10 min), discard the supernatant, wash the precipitate with IMS (2 mL, 50%) and centrifuge, discard the supernatant and invert the test tube on absorbent paper to absorb the liquid, then add KOH solution (2 mol / L, 2 mL) and a magnetic rotor to the sample and stir in an ice water bath for 20 min, add 8 mL of sodium acetate buffer solution and 0.1 mL of AMG, then oscillate in a water bath (50°C, 30 min). After taking out, for samples with a resistant starch mass fraction greater than 10%, wash with distilled water and centrifuge three times to collect the supernatant, and fix the volume to 100 mL. For samples with a resistant starch mass fraction less than 10%, directly centrifuge and collect the supernatant. Finally, determine the glucose content in the supernatant and convert it into starch content.

[0061] 1.5 Data Analysis

[0062] Excel 2023 was used for data statistics, and R 4.3.0 was used for data analysis. The LSD test was used for analysis of variance between groups, and P < 0.05 was considered statistically significant.

[0063] 2 Results and analysis

[0064] 2.1 Effects of foliar fertilizer spraying on rice yield and quality indicators

[0065] As shown in Table 3, in terms of rice yield, compared with the control group, the yield of multiple treatment combinations increased, but there were certain differences in rice biomass and brown rice yield among the treatments, and they reached a significant level. This shows that the best combination of spraying mixed selenium liquid fertilizer can effectively improve rice growth and increase yield.

[0066] In terms of the selenium content in brown rice, compared with the control, different treatments can increase the selenium content in brown rice. Among them, the selenium content of the T2 combination is relatively high, especially in the filling period, reaching 0.795 mg / kg. The selenium content in brown rice is significantly increased, which is 156.61% higher than that of the control group.

[0067] In terms of the organic selenium content of brown rice, compared with the control, different treatments can increase the organic selenium content of brown rice. The organic selenium content of the T2 combination treated at different periods is relatively high, especially in the filling period, reaching 0.681 mg / kg. The organic selenium content in brown rice is significantly increased, about 21 times compared with the control group. It is worth noting that selenomethylcysteine ​​(MeSeCys) was detected in multiple combinations treated at the booting stage and the filling period, with a content between 0.013 and 0.026 mg / kg, and the effect was better in the filling period, while it was not detected in the control group.

[0068] In terms of the resistant starch content of brown rice, compared with the control, different treatments can increase the resistant starch content of rice brown rice. The effect in the filling period is significantly better than that in other periods. The content of the T2 combination is as high as 6.628 mg / g, which is 1.15 times higher than that of the control.

[0069] The embodiments described above are only preferred embodiments of the present invention and are only used to explain the present invention, not to limit the scope of implementation of the present invention. For those skilled in the art, other implementation methods can certainly be easily made by replacement or modification based on the technical contents disclosed in this specification. Therefore, all changes and improvements made on the principles of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. Application of selenium-rich foliar fertilizer in improving the nutrient content of rice, characterized in that: The selenium-rich foliar fertilizer is composed of the following raw material ratios in parts by weight: sodium selenite, selenomethionine and biological nano-selenium in a ratio of 1200:300:0.1, and the nutritional components include total selenium, selenomethylcysteine ​​and resistant starch.

2. The use according to claim 1, characterized in that: When the selenium-rich foliar fertilizer is used, first dilute 150.03 g of selenium-rich foliar fertilizer to 60 L, and then dilute at 30 L / hm2 each time. 2 Spray the amount evenly on the rice leaves in 2 times.

3. The use according to claim 2, characterized in that: The spraying period is within 5 to 10 days from the beginning of rice heading to grain filling period.

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

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