Selenium-rich polygonum multiflorum planting and selenium content regulation method

Abstract

This invention discloses a method for cultivating selenium-enriched Polygonatum and regulating its selenium content: S1. Selenium-enriched seed tuber initiation: After disinfecting the Polygonatum seed tubers, they are placed in a selenium-enriched initiation medium containing 0.5 mg / L-2.0 mg / L sodium selenite for directional culture until the seed tubers sprout new buds and induce new fibrous roots; S2. Basal application of selenium: The seed tubers that have sprouted new buds are transplanted to the field, and a compound selenium-enriched base fertilizer is applied before transplanting. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant; S3. Dynamic topdressing during the growth period: During the leaf expansion stage and root and stem enlargement stage of Polygonatum, organic chelated selenium fertilizers of different concentration gradients are sprayed or topdressed according to the target selenium content level; S4. Metabolic regulation before harvest: 30-50 days before the expected harvest, the supply of exogenous selenium is stopped, and a metabolic regulator is sprayed to promote the conversion of inorganic selenium in the plant into organic selenium.

Description

Technical Field

[0001] This invention belongs to the field of Polygonatum cultivation technology, and particularly relates to the cultivation of selenium-enriched Polygonatum and methods for regulating selenium content. Background Technology

[0002] Polygonatum is a perennial herb belonging to the Polygonatum genus of the Liliaceae family. It is an important Chinese medicinal material that is both food and medicine. Selenium-enriched Polygonatum combines the inherent effects of Polygonatum with the physiological activities of selenium, such as anti-oxidation and immune enhancement, and its market demand is growing.

[0003] Current methods for cultivating selenium-enriched Polygonatum mostly employ soil basal application of sodium selenite combined with foliar spraying of selenium fertilizer. However, none of these methods utilize concentration gradient control based on the varying selenium requirements of Polygonatum at different growth stages. This leads to selenium stress and seedling burn in the early stages, and low selenium conversion efficiency in the later stages. Specifically, during the leaf expansion stage, the plant's leaves are tender and have low tolerance to selenium; high concentrations can easily cause oxidative stress, resulting in symptoms such as leaf margin scorching and stunted growth. During the rhizome enlargement stage, the underground rhizomes expand rapidly, significantly increasing the demand for selenium; low concentrations are insufficient to meet the accumulation requirements, leading to inadequate selenium absorption and decreased organic selenium conversion efficiency. This mismatch between concentration and growth stage requirements hinders further improvements in selenium fertilizer utilization efficiency and the quality of selenium-enriched Polygonatum. Summary of the Invention

[0004] To address the problems in the prior art, the present invention proposes the following technical solution: This invention provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, comprising the following steps: S1. Selenium-enriched start-up of rhizomes: After disinfecting the rhizomes of Polygonatum, place them in a selenium-enriched start-up medium containing 0.5 mg / L-2.0 mg / L sodium selenite for directional culture until the rhizomes sprout new buds and induce new fibrous roots; S2, Base application of selenium: Transplant the seedlings that have sprouted new buds to the field, and apply compound selenium-enriched base fertilizer before transplanting. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant. S3. Dynamic topdressing during the growth period: During the leaf expansion and rhizome enlargement stages of Polygonatum, apply organic chelated selenium fertilizer at different concentration gradients according to the target selenium content level. S4. Pre-harvest metabolic regulation: 30-50 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium to organic selenium in the plant.

[0005] In step S3, During the leaf expansion stage, apply organic chelated selenium fertilizer at the first concentration range for foliar spraying to induce the activity of selenium metabolism-related enzymes in the plant. During the rhizome enlargement period, apply organic chelated selenium fertilizer at a concentration range higher than the first concentration range to the roots to promote the absorption and accumulation of selenium in the rhizomes. The first concentration range during the leaf expansion stage is lower than the second concentration range during the root and stem enlargement stage.

[0006] As a preferred embodiment of the above technical solution, in step S1, the specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic culture medium, 0.5-2 parts sodium selenite, 1-1.5 parts 6-benzylaminopurine, 0.1-0.5 parts naphthaleneacetic acid, and 30 parts sucrose.

[0007] As a preferred embodiment of the above technical solution, in step S2, the nano-selenium activated mineral powder is selenium-rich shale powder or Ziyang stone powder with a particle size D90≤50μm.

[0008] As a preferred embodiment of the above technical solution, in step S2, the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi.

[0009] As a preferred embodiment of the above technical solution, in step S2, the mass ratio of nano-selenium activated mineral powder to microbial composite inoculant is 100:(2-5).

[0010] As a preferred embodiment of the above technical solution, in step S3, the organic chelated selenium fertilizer is a chelate of selenomethionine or selenocysteine ​​and fulvic acid.

[0011] As a preferred embodiment of the above technical solution, in step S3, the first concentration range during the leaf expansion period is a selenium content of 50 mg / L-100 mg / L, and the second concentration range during the root and stem enlargement period is a selenium content of 150 mg / L-200 mg / L.

[0012] As a preferred embodiment of the above technical solution, in step S3, organic chelated selenium fertilizer is sprayed twice during the leaf expansion period, with an interval of 7-10 days between each application; during the root and stem enlargement period, organic chelated selenium fertilizer is applied three times through a drip irrigation system, with an interval of 10-15 days between each application.

[0013] As a preferred embodiment of the above technical solution, in step S4, the metabolic regulator is a salicylic acid or methyl jasmonate solution with a mass concentration of 0.01%-0.05%.

[0014] The beneficial effects of this invention are as follows: (1) This invention combines seed tuber selenium enrichment initiation with basal application of selenium. First, during the seed tuber germination stage, the seed tuber is induced to establish selenium metabolism capacity through a culture medium containing sodium selenite at 0.5 mg / L-2.0 mg / L. Then, through the slow-release supply of nano-selenium activated mineral powder and microbial compound inoculant in S2, the selenium supply rhythm in the soil is matched with the early selenium absorption capacity of the plant, which significantly improves the selenium utilization efficiency in the entire early growth stage.

[0015] (2) In this invention, a gradient regulation method is adopted in S3, which involves low-concentration foliar spraying during the leaf expansion period to induce enzyme activity and high-concentration drip irrigation during the root and stem enlargement period to promote absorption. This method is combined with S1 and S2: S1 and S2 enable the plant to accumulate a certain selenium metabolism base in the early stage. The low concentration in S3 during the leaf expansion period further activates the activity of selenium metabolism-related enzymes, which provides sufficient metabolic capacity for high-concentration absorption during the root and stem enlargement period. This achieves a smooth transition from induction to enrichment, avoiding selenium stress caused by high concentration throughout the growth period and overcoming insufficient absorption in the later stage caused by uniform low concentration.

[0016] (3) In the metabolic regulation before harvesting in S4, the present invention sprays 0.01%-0.05% salicylic acid or methyl jasmonate. This step echoes S3: the supply of high concentration of organic chelated selenium fertilizer in S3 makes the plant accumulate sufficient selenium. S4 induces the conversion of these accumulated selenium into organic selenium through signaling substances. The above-mentioned process steps of conversion after supply effectively solve the problems of low organic selenium ratio and high inorganic selenium residue in the prior art. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0018] Unless otherwise specified, the main components involved in the following embodiments of this application are all purchased from commercially available products.

[0019] To address the need for selenium content regulation in the cultivation of selenium-enriched Polygonatum, this application achieves precise graded regulation of selenium content through a four-step synergistic approach: S1 selenium enrichment in the seed stem, S2 basal application for selenium fixation, S3 dynamic topdressing during the growth period, and S4 metabolic regulation before harvest.

[0020] In the S1 seed stem selenium-enriched initiation step, the Polygonatum rhizomes are placed in a selenium-enriched initiation medium containing sodium selenite for directional culture. 6-Benzylaminopurine (6-BA) and naphthaleneacetic acid (NAA) in the medium act as plant growth regulators to promote seed stem germination and fibrous root induction. Sodium selenite, as a selenium source, is absorbed during the seed stem germination stage, enabling the plant to establish selenium metabolism capacity at an early stage. Sucrose provides energy as a carbon source. The core of this step is to forcibly induce the absorption of selenium during the seed stem stage, making it adapt to and depend on selenium, thereby significantly improving the selenium conversion efficiency in later field planting.

[0021] In the S2 selenium fixation step, the nano-selenium activated mineral powder is a modified selenium-rich shale or Ziyang stone powder, which provides a slow-release selenium source; Bacillus subtilis in the microbial compound agent has the ability to reduce sodium selenite to nano-elemental selenium, and arbuscular mycorrhizal fungi can coexist with the roots of Polygonatum sibiricum to expand the root absorption area. The two work together to establish a long-term selenium supply system in the soil.

[0022] In the S3 growth period dynamic topdressing steps, low-concentration organic chelated selenium fertilizer is applied as a foliar spray during the leaf expansion stage. Its main function is to induce the activity of selenium metabolism-related enzymes (such as ATP sulfonase and APS reductase) in the plant, and to avoid oxidative stress on young leaves caused by high concentrations. During the root and stem enlargement stage, high-concentration organic chelated selenium fertilizer is applied as a root topdressing. At this time, the biomass of Polygonatum plants is large and their tolerance is strong, so they can quickly absorb selenium and transport it to the root and stem.

[0023] In the S4 pre-harvest metabolic regulation step, exogenous selenium supply is stopped 30-50 days before harvest, and salicylic acid or methyl jasmonate is sprayed. These two signaling substances can induce the key enzymes of sulfur metabolism (ATPS / APS) in the plant to convert inorganic selenium into selenocysteine ​​and selenomethionine, thereby increasing the proportion of organic selenium in the harvested Polygonatum rhizomes, significantly reducing inorganic selenium residues, and improving product safety.

[0024] Example 1

[0025] This embodiment provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, including the following steps: S1. Selenium-enriched seed tuber initiation: Select healthy, pest-free rhizomes of Polygonatum odoratum as seed tubers. Disinfect with 75% ethanol for 30 seconds, then with 0.1% mercuric chloride for 10 minutes, and rinse with sterile water 3-5 times. Place the disinfected seed tubers in a selenium-enriched initiation medium for directional culture at a temperature of 25℃±2℃, a light intensity of 2500±500 Lux, a photoperiod of 12 hours / day, and for 25±5 days until the seed tubers sprout new buds and induce new fibrous roots.

[0026] The specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic culture medium, 1.2 parts sodium selenite, 1.2 parts 6-benzylaminopurine, 0.3 parts naphthaleneacetic acid, and 30 parts sucrose.

[0027] S2. Base application of selenium: Transplant the newly sprouted seedlings to the field. Before transplanting, apply a compound selenium-enriched base fertilizer during land preparation. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant: the nano-selenium activated mineral powder is selenium-enriched shale powder with a particle size D90≤50μm, and the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi, among which the effective viable count of Bacillus subtilis is ≥1×10⁻⁶. 8 CFU / g, infection rate of arbuscular mycorrhizal fungi ≥70%. The mass ratio of nano-selenium activated mineral powder to microbial compound inoculant is 100:3.5, and the application rate of compound selenium-enriched base fertilizer is 250 kg per mu.

[0028] S3. Dynamic topdressing during the growth period: Based on the target selenium content level, this embodiment is set to the selenium-rich level, with a target total selenium content range of 0.15 mg / kg-0.50 mg / kg. Different concentration gradients of organic chelated selenium fertilizer are sprayed or topdressed during the leaf expansion stage and the root and stem enlargement stage of Polygonatum. Organic chelated selenium fertilizer is a chelate of selenomethionine and fulvic acid. The preparation method is as follows: dissolve selenomethionine powder in deionized water, add fulvic acid at a mass ratio of 1:5, and ultrasonically chelate for 30 minutes at pH 6.2 and 40℃, then dilute to the required concentration.

[0029] During the leaf expansion period, apply organic chelated selenium fertilizer with a selenium content of 75 mg / L as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant. Spray twice, with an interval of 8 days between each application. Apply 35 liters of diluted solution per acre each time, preferably after 16:00 in the evening, ensuring that both sides of the leaves are evenly moistened.

[0030] During the rhizome enlargement period, apply organic chelated selenium fertilizer with a selenium content of 175 mg / L to the roots to promote the absorption and accumulation of selenium in the rhizomes. Apply through a drip irrigation system, for a total of 3 applications, each 12 days apart. Apply 250 liters of diluted solution per acre each time, ensuring the rhizome layer is moistened to a depth of 15-20 cm. Also, add 0.2% potassium dihydrogen phosphate.

[0031] S4. Pre-harvest metabolic regulation: 40 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium.

[0032] The metabolic regulator is a 0.03% salicylic acid solution, applied by foliar spraying, for a total of 2 sprays, 10 days apart, with 30 liters per acre each time.

[0033] Example 2

[0034] This embodiment provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, including the following steps: S1. Selenium-enriched seed tuber initiation: Select healthy, pest-free rhizomes of Polygonatum odoratum as seed tubers. Disinfect with 75% ethanol for 30 seconds, then with 0.1% mercuric chloride for 10 minutes, and rinse with sterile water 3-5 times. Place the disinfected seed tubers in a selenium-enriched initiation medium for directional culture at a temperature of 25℃±2℃, a light intensity of 2500±500 Lux, a photoperiod of 12 hours / day, and for 25±5 days until the seed tubers sprout new buds and induce new fibrous roots.

[0035] The specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic medium, 0.5 parts sodium selenite, 1.0 part 6-benzylaminopurine, 0.1 part naphthaleneacetic acid, and 30 parts sucrose.

[0036] S2. Base application of selenium: Transplant the newly sprouted seedlings to the field. Before transplanting, apply a compound selenium-enriched base fertilizer during land preparation. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant: the nano-selenium activated mineral powder is Ziyang stone powder with a particle size D90≤50μm, and the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi, among which the effective viable count of Bacillus subtilis is ≥1×10⁻⁶. 8 CFU / g, infection rate of arbuscular mycorrhizal fungi ≥70%. The mass ratio of nano-selenium activated mineral powder to microbial compound inoculant is 100:2, and the application rate of compound selenium-enriched base fertilizer is 200 kg per mu.

[0037] S3. Dynamic topdressing during the growth period: Based on the target selenium content level, this embodiment is set to the selenium-rich level, with a target total selenium content range of 0.15 mg / kg-0.50 mg / kg. Organic chelated selenium fertilizers of different concentration gradients are sprayed or topdressed during the leaf expansion stage and the rhizome enlargement stage of Polygonatum.

[0038] Organic chelated selenium fertilizer is a chelate of selenomethionine and fulvic acid. The preparation method is as follows: dissolve selenomethionine powder in deionized water, add fulvic acid at a mass ratio of 1:5, and ultrasonically chelate for 30 minutes at pH 6.2 and 40℃, then dilute to the required concentration.

[0039] During the leaf expansion period, apply organic chelated selenium fertilizer with a selenium content of 50 mg / L as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant. Spray twice, with an interval of 7 days between each application. Apply 30 liters of diluted solution per acre each time, preferably after 16:00 in the evening, ensuring that both sides of the leaves are evenly moistened.

[0040] During the rhizome enlargement period, apply organic chelated selenium fertilizer with a selenium content of 150 mg / L to the roots to promote the absorption and accumulation of selenium in the rhizomes. Apply through a drip irrigation system, for a total of 3 applications, each 10 days apart. Apply 200 liters of diluted solution per acre each time, ensuring the rhizome layer is moistened to a depth of 15-20 cm. Also, add 0.2% potassium dihydrogen phosphate.

[0041] S4. Pre-harvest metabolic regulation: 30 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium.

[0042] The metabolic regulator is a 0.01% methyl jasmonate solution, applied by foliar spraying, for a total of 2 sprays, 10 days apart, with 30 liters per acre each time.

[0043] Example 3

[0044] This embodiment provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, including the following steps: S1. Selenium-enriched seed tuber initiation: Select healthy, pest-free rhizomes of Polygonatum odoratum as seed tubers. Disinfect with 75% ethanol for 30 seconds, then with 0.1% mercuric chloride for 10 minutes, and rinse with sterile water 3-5 times. Place the disinfected seed tubers in a selenium-enriched initiation medium for directional culture at a temperature of 25℃±2℃, a light intensity of 2500±500 Lux, a photoperiod of 12 hours / day, and for 25±5 days until the seed tubers sprout new buds and induce new fibrous roots.

[0045] The specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic culture medium, 2.0 parts sodium selenite, 1.5 parts 6-benzylaminopurine, 0.5 parts naphthaleneacetic acid, and 30 parts sucrose.

[0046] S2. Base application of selenium: Transplant the newly sprouted seedlings to the field. Before transplanting, apply a compound selenium-enriched base fertilizer during land preparation. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant: the nano-selenium activated mineral powder is selenium-enriched shale powder with a particle size D90≤50μm, and the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi, among which the effective viable count of Bacillus subtilis is ≥1×10⁻⁶. 8 CFU / g, infection rate of arbuscular mycorrhizal fungi ≥70%. The mass ratio of nano-selenium activated mineral powder to microbial compound inoculant is 100:5, and the application rate of compound selenium-enriched base fertilizer is 300 kg per mu.

[0047] S3. Dynamic topdressing during the growth period: Based on the target selenium content level, this embodiment is set to high selenium level, with a target total selenium content range of 0.50 mg / kg-1.50 mg / kg. Organic chelated selenium fertilizers of different concentration gradients are sprayed or topdressed during the leaf expansion stage and the rhizome enlargement stage of Polygonatum.

[0048] Organic chelated selenium fertilizer is a chelate of selenomethionine and fulvic acid. The preparation method is as follows: dissolve selenomethionine powder in deionized water, add fulvic acid at a mass ratio of 1:5, and ultrasonically chelate for 30 minutes at pH 6.2 and 40℃, then dilute to the required concentration.

[0049] During the leaf expansion period, apply organic chelated selenium fertilizer with a selenium content of 100 mg / L as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant. Spray twice, with an interval of 10 days between each application. Apply 40 liters of diluted solution per acre each time, preferably after 16:00 in the evening, ensuring that both sides of the leaves are evenly moistened.

[0050] During the rhizome enlargement period, apply organic chelated selenium fertilizer with a selenium content of 200 mg / L to the roots to promote the absorption and accumulation of selenium in the rhizomes. Apply through a drip irrigation system, for a total of 3 applications, each 15 days apart. Apply 300 liters of diluted solution per acre each time, ensuring the rhizome layer is moistened to a depth of 15-20 cm. Also, add 0.2% potassium dihydrogen phosphate.

[0051] S4. Pre-harvest metabolic regulation: 50 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium.

[0052] The metabolic regulator is a 0.05% salicylic acid solution, applied by foliar spraying, for a total of 2 sprays, 10 days apart, with 30 liters per acre each time.

[0053] Example 4

[0054] This embodiment provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, including the following steps: S1. Selenium-enriched seed tuber initiation: Select healthy, pest-free rhizomes of Polygonatum odoratum as seed tubers. Disinfect with 75% ethanol for 30 seconds, then with 0.1% mercuric chloride for 10 minutes, and rinse with sterile water 3-5 times. Place the disinfected seed tubers in a selenium-enriched initiation medium for directional culture at a temperature of 25℃±2℃, a light intensity of 2500±500 Lux, a photoperiod of 12 hours / day, and for 25±5 days until the seed tubers sprout new buds and induce new fibrous roots.

[0055] The specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic medium, 0.5 parts sodium selenite, 1.2 parts 6-benzylaminopurine, 0.3 parts naphthaleneacetic acid, and 30 parts sucrose.

[0056] S2. Base application of selenium: Transplant the newly sprouted seedlings to the field. Before transplanting, apply a compound selenium-enriched base fertilizer during land preparation. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant: the nano-selenium activated mineral powder is Ziyang stone powder with a particle size D90≤50μm, and the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi, among which the effective viable count of Bacillus subtilis is ≥1×10⁻⁶. 8 CFU / g, infection rate of arbuscular mycorrhizal fungi ≥70%. The mass ratio of nano-selenium activated mineral powder to microbial compound inoculant is 100:3.5, and the application rate of compound selenium-enriched base fertilizer is 250 kg per mu.

[0057] S3. Dynamic topdressing during the growth period: Based on the target selenium content level, this embodiment is set to the selenium-rich level, with a target total selenium content range of 0.15 mg / kg-0.50 mg / kg. Organic chelated selenium fertilizers of different concentration gradients are sprayed or topdressed during the leaf expansion stage and the rhizome enlargement stage of Polygonatum.

[0058] Organic chelated selenium fertilizer is a chelate of selenomethionine and fulvic acid. The preparation method is as follows: dissolve selenomethionine powder in deionized water, add fulvic acid at a mass ratio of 1:5, and ultrasonically chelate for 30 minutes at pH 6.2 and 40℃, then dilute to the required concentration.

[0059] During the leaf expansion period, apply organic chelated selenium fertilizer with a selenium content of 75 mg / L as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant. Spray twice, with an interval of 8 days between each application. Apply 35 liters of diluted solution per acre each time, preferably after 16:00 in the evening, ensuring that both sides of the leaves are evenly moistened.

[0060] During the rhizome enlargement period, apply organic chelated selenium fertilizer with a selenium content of 150 mg / L to the roots to promote the absorption and accumulation of selenium in the rhizomes. Apply through a drip irrigation system, for a total of 3 applications, each 12 days apart. Apply 250 liters of diluted solution per acre each time, ensuring the rhizome layer is moistened to a depth of 15-20 cm. Add 0.2% potassium dihydrogen phosphate in conjunction.

[0061] S4. Pre-harvest metabolic regulation: 40 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium.

[0062] The metabolic regulator is a 0.03% methyl jasmonate solution, applied by foliar spraying, for a total of 2 sprays, 10 days apart, with 30 liters per acre each time.

[0063] Example 5

[0064] This embodiment provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, including the following steps: S1. Selenium-enriched seed tuber initiation: Select healthy, pest-free rhizomes of Polygonatum odoratum as seed tubers. Disinfect with 75% ethanol for 30 seconds, then with 0.1% mercuric chloride for 10 minutes, and rinse with sterile water 3-5 times. Place the disinfected seed tubers in a selenium-enriched initiation medium for directional culture at a temperature of 25℃±2℃, a light intensity of 2500±500 Lux, a photoperiod of 12 hours / day, and for 25±5 days until the seed tubers sprout new buds and induce new fibrous roots.

[0065] The specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic culture medium, 1.2 parts sodium selenite, 1.2 parts 6-benzylaminopurine, 0.3 parts naphthaleneacetic acid, and 30 parts sucrose.

[0066] S2. Base application of selenium: Transplant the newly sprouted seedlings to the field. Before transplanting, apply a compound selenium-enriched base fertilizer during land preparation. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant: the nano-selenium activated mineral powder is selenium-enriched shale powder with a particle size D90≤50μm, and the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi, among which the effective viable count of Bacillus subtilis is ≥1×10⁻⁶. 8CFU / g, infection rate of arbuscular mycorrhizal fungi ≥70%. The mass ratio of nano-selenium activated mineral powder to microbial compound inoculant is 100:3.5, and the application rate of compound selenium-enriched base fertilizer is 250 kg per mu.

[0067] S3. Dynamic topdressing during the growth period: Based on the target selenium content level, this embodiment is set to high selenium level, with a target total selenium content range of 0.50 mg / kg-1.50 mg / kg. Organic chelated selenium fertilizers of different concentration gradients are sprayed or topdressed during the leaf expansion stage and the rhizome enlargement stage of Polygonatum.

[0068] Organic chelated selenium fertilizer is a chelate of selenomethionine and fulvic acid. The preparation method is as follows: dissolve selenomethionine powder in deionized water, add fulvic acid at a mass ratio of 1:5, and ultrasonically chelate for 30 minutes at pH 6.2 and 40℃, then dilute to the required concentration.

[0069] During the leaf expansion period, apply organic chelated selenium fertilizer with a selenium content of 75 mg / L as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant. Spray twice, with an interval of 8 days between each application. Apply 35 liters of diluted solution per acre each time, preferably after 16:00 in the evening, ensuring that both sides of the leaves are evenly moistened.

[0070] During the rhizome enlargement period, apply organic chelated selenium fertilizer with a selenium content of 200 mg / L to the roots to promote the absorption and accumulation of selenium in the rhizomes. Apply through a drip irrigation system, for a total of 3 applications, each 12 days apart. Apply 250 liters of diluted solution per acre each time, ensuring the rhizome layer is moistened to a depth of 15-20 cm. Also, add 0.2% potassium dihydrogen phosphate.

[0071] S4. Pre-harvest metabolic regulation: 40 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium.

[0072] The metabolic regulator is a 0.03% salicylic acid solution, applied by foliar spraying, for a total of 2 sprays, 10 days apart, with 30 liters per acre each time.

[0073] Example 6

[0074] This embodiment provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, including the following steps: S1. Selenium-enriched seed tuber initiation: Select healthy, pest-free rhizomes of Polygonatum sibiricum as seed tubers. Disinfect with 75% ethanol for 30 seconds, then with 0.1% mercuric chloride for 10 minutes, and rinse with sterile water 3-5 times. Place the disinfected seed tubers in a selenium-enriched initiation medium for directional culture at a temperature of 25℃±2℃, a light intensity of 2500±500 Lux, a photoperiod of 12 hours / day, and for 25±5 days until the seed tubers sprout new buds and induce new fibrous roots.

[0075] The specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic culture medium, 1.2 parts sodium selenite, 1.2 parts 6-benzylaminopurine, 0.3 parts naphthaleneacetic acid, and 30 parts sucrose.

[0076] S2. Base application of selenium: Transplant the newly sprouted seedlings to the field. Before transplanting, apply a compound selenium-enriched base fertilizer during land preparation. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant: the nano-selenium activated mineral powder is selenium-enriched shale powder with a particle size D90≤50μm, and the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi, among which the effective viable count of Bacillus subtilis is ≥1×10⁻⁶. 8 CFU / g, infection rate of arbuscular mycorrhizal fungi ≥70%. The mass ratio of nano-selenium activated mineral powder to microbial compound inoculant is 100:3.5, and the application rate of compound selenium-enriched base fertilizer is 250 kg per mu.

[0077] S3. Dynamic topdressing during the growth period: Based on the target selenium content level, this embodiment is set to the selenium-rich level, with a target total selenium content range of 0.15 mg / kg-0.50 mg / kg. Organic chelated selenium fertilizers of different concentration gradients are sprayed or topdressed during the leaf expansion stage and the rhizome enlargement stage of Polygonatum.

[0078] Organic chelated selenium fertilizer is a chelate of selenomethionine and fulvic acid. The preparation method is as follows: dissolve selenomethionine powder in deionized water, add fulvic acid at a mass ratio of 1:5, and ultrasonically chelate for 30 minutes at pH 6.2 and 40℃, then dilute to the required concentration.

[0079] During the leaf expansion period, apply organic chelated selenium fertilizer with a selenium content of 75 mg / L as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant. Spray twice, with an interval of 8 days between each application. Apply 35 liters of diluted solution per acre each time, preferably after 16:00 in the evening, ensuring that both sides of the leaves are evenly moistened.

[0080] During the rhizome enlargement period, apply organic chelated selenium fertilizer with a selenium content of 175 mg / L to the roots to promote the absorption and accumulation of selenium in the rhizomes. Apply through a drip irrigation system, for a total of 3 applications, each 12 days apart. Apply 250 liters of diluted solution per acre each time, ensuring the rhizome layer is moistened to a depth of 15-20 cm. Add 0.2% potassium dihydrogen phosphate in conjunction.

[0081] S4. Pre-harvest metabolic regulation: 40 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium.

[0082] The metabolic regulator is a 0.03% salicylic acid solution, applied by foliar spraying, for a total of 2 sprays, 10 days apart, with 30 liters per acre each time.

[0083] Example 7

[0084] This embodiment provides a method for cultivating selenium-enriched Polygonatum and regulating its selenium content, including the following steps: S1. Selenium-enriched seed tuber initiation: Select healthy, pest-free rhizomes of Polygonatum odoratum as seed tubers. Disinfect with 75% ethanol for 30 seconds, then with 0.1% mercuric chloride for 10 minutes, and rinse with sterile water 3-5 times. Place the disinfected seed tubers in a selenium-enriched initiation medium for directional culture at a temperature of 25℃±2℃, a light intensity of 2500±500 Lux, a photoperiod of 12 hours / day, and for 25±5 days until the seed tubers sprout new buds and induce new fibrous roots.

[0085] The specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic culture medium, 1.2 parts sodium selenite, 1.2 parts 6-benzylaminopurine, 0.3 parts naphthaleneacetic acid, and 30 parts sucrose.

[0086] S2. Base application of selenium: Transplant the newly sprouted seedlings to the field. Before transplanting, apply a compound selenium-enriched base fertilizer during land preparation. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant: the nano-selenium activated mineral powder is selenium-enriched shale powder with a particle size D90≤50μm, and the microbial compound inoculant contains Bacillus subtilis and arbuscular mycorrhizal fungi, among which the effective viable count of Bacillus subtilis is ≥1×10⁻⁶. 8 CFU / g, infection rate of arbuscular mycorrhizal fungi ≥70%. The mass ratio of nano-selenium activated mineral powder to microbial compound inoculant is 100:3.5, and the application rate of compound selenium-enriched base fertilizer is 250 kg per mu.

[0087] S3. Dynamic topdressing during the growth period: Based on the target selenium content level, this embodiment is set to the selenium-rich level, with a target total selenium content range of 0.15 mg / kg-0.50 mg / kg. Organic chelated selenium fertilizers of different concentration gradients are sprayed or topdressed during the leaf expansion stage and the rhizome enlargement stage of Polygonatum.

[0088] Organic chelated selenium fertilizer is a chelate of selenocysteine ​​and fulvic acid. The preparation method is as follows: dissolve selenocysteine ​​powder in deionized water, add fulvic acid at a mass ratio of 1:5, and ultrasonically chelate for 30 minutes at pH 6.2 and 40℃, then dilute to the required concentration.

[0089] During the leaf expansion period, apply organic chelated selenium fertilizer with a selenium content of 75 mg / L as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant. Spray twice, with an interval of 8 days between each application. Apply 35 liters of diluted solution per acre each time, preferably after 16:00 in the evening, ensuring that both sides of the leaves are evenly moistened.

[0090] During the rhizome enlargement period, apply organic chelated selenium fertilizer with a selenium content of 175 mg / L to the roots to promote the absorption and accumulation of selenium in the rhizomes. Apply through a drip irrigation system, for a total of 3 applications, each 12 days apart. Apply 250 liters of diluted solution per acre each time, ensuring the rhizome layer is moistened to a depth of 15-20 cm. Add 0.2% potassium dihydrogen phosphate in conjunction.

[0091] S4. Pre-harvest metabolic regulation: 40 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium.

[0092] The metabolic regulator is a 0.03% methyl jasmonate solution, applied by foliar spraying, for a total of 2 sprays, 10 days apart, with 30 liters per acre each time.

[0093] Comparative Example 1 The difference from Example 1 is that in step S1, the seed stems that have been disinfected by soaking in clean water are directly transplanted without being cultured in a selenium-enriched starter culture medium. Other conditions are the same as in Example 1.

[0094] Comparative Example 2 The difference from Example 1 is that in step S3, the same concentration of organic chelated selenium fertilizer (100 mg / L) is used during both the leaf expansion stage and the root and stem enlargement stage, without distinguishing between the first and second concentration ranges, and other conditions are the same as in Example 1.

[0095] Comparative Example 3 The difference from Example 1 is that step S4 is not performed, that is, the metabolic regulator is not sprayed before harvest, and the harvest is carried out directly, while the other conditions are the same as in Example 1.

[0096] Comparative Example 4 The difference from Example 1 is that sodium selenite is used instead of organic chelated selenium fertilizer in step S3, while the concentration and number of applications remain unchanged, and other conditions are the same as in Example 1.

[0097] The methods of Examples 1 to 7 and Comparative Examples 1 to 4 were subjected to performance tests to detect the total selenium content and the proportion of organic selenium in the rhizome of Polygonatum odoratum. The results are shown in Table 1.

[0098] Table 1 As shown in Table 1, the organic selenium content in Examples 1 to 7 all reached over 86%, which was significantly better than that in Comparative Examples 1 to 4. The total selenium content in Examples 1, 2, 4, 6, and 7 was controlled within the target range for selenium enrichment; the total selenium content in Examples 3 and 5 was controlled within the target range for high selenium, achieving precise graded control of selenium content.

[0099] Comparative Example 1 had a total selenium content of 0.21 mg / kg and an organic selenium content of 72.5%, indicating that step S1 enabled Polygonatum to establish selenium metabolism capacity during the seed germination stage, significantly initiating selenium absorption in later stages. Comparative Example 2 had a total selenium content of 0.52 mg / kg, higher than some examples, but the organic selenium content was only 68.3%, and slight leaf yellowing occurred during the leaf expansion stage. This verified that the gradient regulation strategy of low-concentration induction during leaf expansion and high-concentration absorption promotion during root and stem enlargement can avoid early selenium stress while ensuring efficient conversion of organic selenium in later stages. Comparative Example 3 had an organic selenium content of only 61.7%, confirming that spraying salicylic acid or methyl jasmonate before harvest can effectively induce the activity of key enzymes in selenium metabolism, promoting the conversion of inorganic selenium to selenoamino acids in the plant. Comparative Example 4 had an organic selenium content of only 58.9%, indicating that the organic selenium fertilizer formed by the chelation of selenomethionine or selenocysteine ​​with fulvic acid is more conducive to the absorption and accumulation of organic selenium by Polygonatum.

[0100] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A method for cultivating selenium-enriched Polygonatum and regulating its selenium content, characterized in that, Includes the following steps: S1. Selenium-enriched start-up of rhizomes: After disinfecting the rhizomes of Polygonatum, place them in a selenium-enriched start-up medium containing 0.5 mg / L-2.0 mg / L sodium selenite for directional culture until the rhizomes sprout new buds and induce new fibrous roots; S2, Base application of selenium: Transplant the seedlings that have sprouted new buds to the field, and apply compound selenium-enriched base fertilizer before transplanting. The compound selenium-enriched base fertilizer contains nano-selenium activated mineral powder and microbial compound inoculant. S3. Dynamic topdressing during the growth period: During the leaf expansion and rhizome enlargement stages of Polygonatum, apply organic chelated selenium fertilizer at different concentration gradients according to the target selenium content level. S4. Pre-harvest metabolic regulation: 30-50 days before the expected harvest, stop the supply of exogenous selenium and spray a metabolic regulator to promote the conversion of inorganic selenium in the plant into organic selenium. In step S3, during the leaf expansion period, organic chelated selenium fertilizer in the first concentration range is applied as a foliar spray to induce the activity of selenium metabolism-related enzymes in the plant; during the root and stem enlargement period, organic chelated selenium fertilizer in the second concentration range higher than the first concentration range is applied as a top dressing to the roots to promote the absorption and accumulation of selenium by the roots and stems; the first concentration range during the leaf expansion period is lower than the second concentration range during the root and stem enlargement period.

2. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S1, the specific formula of the selenium-enriched starter culture medium is as follows: by weight, 1 part MS basic culture medium, 0.5-2 parts sodium selenite, 1-1.5 parts 6-benzylaminopurine, 0.1-0.5 parts naphthaleneacetic acid, and 30 parts sucrose.

3. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S2, the nano-selenium activated mineral powder is selenium-rich shale powder or Ziyang stone powder with a particle size D90≤50μm.

4. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S2, the microbial compound agent contains Bacillus subtilis and arbuscular mycorrhizal fungi.

5. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S2, the mass ratio of nano-selenium activated mineral powder to microbial composite inoculant is 100:(2-5).

6. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S3, the organic chelated selenium fertilizer is a chelate of selenomethionine or selenocysteine ​​with fulvic acid.

7. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S3, the first concentration range during the leaf expansion stage is 50 mg / L-100 mg / L of selenium, and the second concentration range during the root and stem enlargement stage is 150 mg / L-200 mg / L of selenium.

8. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S3, organic chelated selenium fertilizer is sprayed twice during the leaf expansion period, with an interval of 7-10 days between each application; during the root and stem enlargement period, organic chelated selenium fertilizer is applied three times through the drip irrigation system, with an interval of 10-15 days between each application.

9. The method for cultivating selenium-enriched Polygonatum and regulating its selenium content according to claim 1, characterized in that, In step S4, the metabolic regulator is a salicylic acid or methyl jasmonate solution with a mass concentration of 0.01%-0.05%.

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