A cultivation method for improving the content of secalin in secale cereale

Abstract

The present application relates to the cultivation planting technical field, specifically relates to a kind of cultivation method for increasing arabinogalactan content of Huangjing, the relative water content of cultivation soil is controlled at 45%~50% in the vigorous growth period of Huangjing, while the salt content of soil is controlled at 0.2%~0.3%.The present application utilizes the synergistic effect of mild drought stress and mild salt stress, activates the secondary metabolic pathway of Huangjing, significantly promotes the synthesis and accumulation of arabinogalactan in rhizome.The salt content of soil is adjusted by applying neutral salt, and gradually reaches the target value within 30~60 days after emergence;Water and salt parameters are precisely and intelligently controlled through a drip irrigation system combined with water and salt sensors.The arabinogalactan content in rhizome of Huangjing cultivated by the present application reaches 4.0%~5.0% after 8 months of growth, breaking through the limitations of traditional high-humidity and low-salt cultivation mode, and significantly improving the medicinal quality and market value of Huangjing.

Description

Technical Field

[0001] This invention relates to the field of cultivation technology, specifically to a cultivation method for increasing the content of arabinogalactan in Polygonatum sibiricum. Background Technology

[0002] Polygonatum is a perennial herb belonging to the genus Polygonatum in the family Liliaceae. It is a commonly used traditional Chinese medicine listed in the Chinese Pharmacopoeia. Its original plants include Polygonatum kingianum Coll. et Hemsl., Polygonatum sibiricum Red., and Polygonatum cyrtonema Hua. Polygonatum has the effects of tonifying qi and nourishing yin, strengthening the spleen and moistening the lungs, and benefiting the kidneys. Modern pharmacological studies have shown that Polygonatum polysaccharides are one of its main active ingredients. Among them, arabinogalactan, as an important functional component of Polygonatum polysaccharides, has significant immunomodulatory, antioxidant, and antitumor activities. Its content directly affects the medicinal quality and market value of Polygonatum.

[0003] However, conventional Polygonatum cultivation techniques have long followed a "high humidity, low salinity" management model. For example, the "Complete Guide to Polygonatum Cultivation" from Yaotong.com instructs that the soil moisture content should be maintained at 60%~70% during the growing season; the Dazhou Municipal Government's "Polygonatum Cultivation Techniques" requires that the field be kept moist for a long time, with watering every 2~4 days during the dry season; other technical data indicates that the soil moisture content should not be lower than 60% during the rhizome enlargement period. At the same time, conventional cultivation seeks the lowest possible soil salinity, usually controlled below 0.05%. Under this model, although Polygonatum accumulates biomass well, the content of arabinogalactan is generally low (usually around 1.5%~1.7%), which seriously restricts the quality improvement of Polygonatum medicinal materials.

[0004] Existing technologies have included studies attempting to increase the polysaccharide content of Polygonatum odoratum through abiotic stress. For example, CN202410751670.0 discloses a processing method for increasing the total polysaccharide content of Polygonatum odoratum using postharvest temperature stress, but its mechanism involves postharvest processing rather than active regulation during cultivation, and its target product is total polysaccharide rather than specific arabinogalactan. Another example is Zhou Hui (CN202011432913.2), who alleviated drought stress by covering with sawdust to prevent yield reduction in Polygonatum odoratum. His aim was to protect yield from drought rather than improve quality, and this study only involved water stress, not salt stress. Furthermore, Yan Li et al. (2021) studied the effect of moderate drought on the accumulation of polysaccharides in Polygonatum odoratum, but this study also only involved water stress, and the target product was generalized total polysaccharide, without specifically increasing the arabinogalactan content.

[0005] In summary, the existing technology has the following shortcomings:

[0006] (1) The content of arabinogalactan is low under the conventional "high humidity and low salt" cultivation mode;

[0007] (2) Existing studies on abiotic stress either focus on postharvest processing or involve only a single stress factor, and the target products are mostly total polysaccharides rather than arabinogalactan.

[0008] Currently, there are no reports on techniques for simultaneously applying water and salt stress during cultivation to directionally increase the arabinogalactan content in Polygonatum sibiricum through the synergistic effect of dual stress. Therefore, there is an urgent need to develop a method that can significantly increase the arabinogalactan content in Polygonatum sibiricum cultivation through dual water and salt stress. Summary of the Invention

[0009] This invention provides a cultivation method that significantly increases the content of arabinogalactan in Polygonatum sibiricum through dual water and salt stress, thereby overcoming the deficiency of low arabinogalactan content in existing Polygonatum sibiricum cultivation techniques.

[0010] This invention is achieved through the following technical solution:

[0011] A cultivation method for increasing the content of arabinogalactan in Polygonatum is provided. During the vigorous growth period of Polygonatum, the relative moisture content of the cultivation soil is controlled at 45%~50%, while the soil salinity is controlled at 0.2%~0.3%. The relative moisture content is calculated as: (actual moisture content ÷ field capacity) × 100%.

[0012] The mechanism of this invention is as follows: Under the dual stress of water and salt, specific sugar metabolism and cell wall polysaccharide synthesis pathways are initiated in the rhizomes of *Polygonatum sibiricum*, and transcriptomic data confirm that the key genes in this pathway are significantly upregulated (log2FC>1.5). Sucrose is first cleaved into UDP-glucose by sucrose synthase 2 (SUS2); subsequently, UDP-glucose is isomerized into UDP-galactose by an epimerase (UGE, log2FC=2.1513); this product is further transported directionally to the Golgi apparatus by UDP-galactose transporter protein (UDP-GALT, log2FC=3.9047), and finally participates in the synthesis of arabinogalactan under the catalysis of galactosyltransferase (GLCAT, log2FC=1.5812). In other words, dual stress synergistically activates the secondary metabolic pathway of *Polygonatum sibiricum*, synergistically activating the expression of multiple key enzyme genes in the arabinogalactan synthesis pathway in the rhizomes of *Polygonatum sibiricum*, thus promoting arabinogalactan synthesis.

[0013] Furthermore, soil salinity is regulated by applying neutral salts, including one or more of sodium chloride and potassium chloride.

[0014] Neutral salts are easy to dissolve and regulate, have little impact on soil physicochemical properties, and are suitable for use in drip irrigation systems.

[0015] Furthermore, when the Solomon's seal seedlings enter their vigorous growth period after emergence, salt regulation is applied to gradually reduce the soil salinity to 0.2% to 0.3% within 30 to 60 days, while maintaining it in sync with the control of relative moisture content of 45% to 50%.

[0016] This gradual introduction of salt stress avoids the acute damage to Polygonatum caused by a sharp increase in salt content, allowing the plant to gradually adapt to the adverse environment and better initiate secondary metabolic responses.

[0017] Furthermore, by using a drip irrigation system in conjunction with soil moisture and salinity sensors for real-time monitoring, drip irrigation is automatically started when the relative soil moisture content is below 45% and stopped when the relative moisture content is above 50%. At the same time, a neutral salt solution is applied through the drip irrigation system to maintain the soil salinity at 0.2% to 0.3%.

[0018] By using a drip irrigation system in conjunction with soil moisture and salinity sensors for real-time monitoring, this intelligent water-salt synergistic control method can precisely maintain the stability of stress conditions and ensure the continuous and efficient accumulation of arabinogalactan.

[0019] The present invention also provides a rhizome of Polygonatum odoratum, which has an arabinogalactan content of 4.0% to 5.0% on a dry weight basis.

[0020] Furthermore, Polygonatum is the original plant of Polygonatum as specified in the Chinese Pharmacopoeia, including Polygonatum yunnanense, Polygonatum sibiricum, or Polygonatum multiflorum.

[0021] The beneficial effects of this invention are:

[0022] I. Significantly Increased Arabingalactan Content: The content of arabinogalactan in the rhizomes of Polygonatum cultivated using the method of this invention can reach 4.0%~5.0% (dry weight ratio) after 8 months of growth, which is 2 to 3 times higher than that of conventional cultivation methods; after 1 month of growth, the average content of arabinogalactan can reach 2.0%~2.1%, which is 30%~40% higher than that of conventional cultivation during the same period, greatly improving the medicinal quality and market value of Polygonatum.

[0023] II. Significant Synergistic Effect: This invention is not a simple superposition of water stress and salt stress, but rather utilizes their synergistic effect mechanism. Experimental data show that the content of arabinogalactan under dual stress (4.91%) is significantly higher than the expected value (3.14%) of the linear superposition of water stress (2.13%) and salt stress (2.69%) alone, with a synergistic effect of 56%. This indicates a positive interaction between mild drought and mild salt stress, which can synergistically activate the secondary metabolic pathways related to arabinogalactan synthesis in Polygonatum sibiricum, producing an unexpected effect of 1+1>2.

[0024] Third, it is simple to operate and low in cost: This invention only requires adding a salt sensor to a conventional drip irrigation system, and can be achieved by adjusting the salt concentration in the irrigation water, without the need for complex equipment modifications or high investments. This method can be integrated with existing agricultural IoT platforms to achieve remote monitoring and automated management, making it suitable for large-scale application in Polygonatum sibiricum planting bases.

[0025] IV. Green and Environmentally Friendly: This invention does not involve chemically synthesized additives or genetic engineering methods. It improves quality only by regulating soil moisture and the content of natural neutral salts (sodium chloride and potassium chloride). It is an environmentally friendly cultivation technique. The Polygonatum medicinal materials produced are highly safe and meet the development requirements of green Chinese medicinal materials.

[0026] In addition, this invention breaks through the traditional cultivation concept of maintaining yield through high humidity and low salt, and proposes a new strategy of promoting quality through stress. By precisely controlling the intensity of adverse stress, the content of target active ingredients is increased in a targeted manner without significantly affecting the biomass of Polygonatum odoratum, providing a technical paradigm that can be referenced for the quality-oriented cultivation of other Chinese medicinal materials. Attached Figure Description

[0027] Figure 1 This is a mechanism diagram illustrating the synthesis mechanism of arabinogalactan in Polygonatum odoratum under the dual stress of water and salt. Detailed Implementation

[0028] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0029] Example 1:

[0030] A cultivation method for increasing the content of arabinogalactan in Polygonatum sibiricum includes the following steps:

[0031] (1) Site selection and land preparation: Select a plot of land with deep, loose, fertile soil, good drainage, and a pH value of 5.5-7.5. During land preparation, plow the land to a depth of 35cm and apply 1500-2000kg of well-rotted organic fertilizer per mu as base fertilizer. Well-rotted organic fertilizer can be one or more combinations of well-rotted farmyard manure, well-rotted stable manure, or well-rotted compost. In this embodiment, well-rotted farmyard manure is used.

[0032] (2) Planting: In late March, select robust 3-year-old Polygonatum rhizomes with intact buds as seedlings. The seed quantity is 150-180 kg per mu, the planting depth is 8-10 cm, and the soil is covered and compacted after planting.

[0033] (3) Field Management: After emergence, the Solomon's seal enters its vigorous growth period. Real-time monitoring is conducted using a drip irrigation system in conjunction with soil moisture and salinity sensors. Drip irrigation automatically starts when the relative soil moisture content is below 45%, and stops when it exceeds 50%. Simultaneously, salinity regulation is applied after emergence and during the vigorous growth period by applying sodium chloride solution (0.1-0.3 mol / L) through the drip irrigation system. This gradually lowers the soil salinity to 0.2%-0.3% within 30-60 days, maintaining it within this range thereafter. Sodium chloride solution is applied every 7-10 days, with a single application rate of 5-10 L per acre.

[0034] (4) Harvesting: The rhizomes are dug up in late October.

[0035] Example 2 (Lower limit of water content):

[0036] The relative soil moisture content is controlled at 43-45%, the salt content is 0.2-0.3%, and the rest is the same as in Example 1.

[0037] Example 3 (Upper Limit of Moisture Content):

[0038] The relative soil moisture content is controlled at 50-52%, the salt content is 0.2-0.3%, and the rest is the same as in Example 1.

[0039] Example 4 (Lower limit of salinity):

[0040] The relative soil moisture content is 45-50%, and the salt content is controlled at 0.18-0.22%, with the rest being the same as in Example 1.

[0041] Example 5 (Upper Limit of Salt Content):

[0042] The relative soil moisture content is 45-50%, and the salt content is controlled at 0.28-0.32%, with the rest being the same as in Example 1.

[0043] Example 6 (Potassium chloride as a salt content regulator - equivalent molar concentration)

[0044] (1) Site selection, land preparation, and planting: Same as in Example 1.

[0045] (2) Field Management: After emergence, the Solomon's seal enters its vigorous growth period. Real-time monitoring is conducted using a drip irrigation system in conjunction with soil moisture and salinity sensors. Drip irrigation automatically starts when the relative soil moisture content is below 45%, and stops when it exceeds 50%. Simultaneously, salinity regulation is applied after emergence and during the vigorous growth period. Potassium chloride solution (concentration 0.1~0.3 mol / L, equivalent to the molar concentration of sodium chloride solution in Example 1) is applied through the drip irrigation system to gradually reduce soil salinity to 0.2%~0.3% within 30~60 days, and then maintains it within this range. Potassium chloride solution is applied every 7~10 days, with a single application rate of 5~10 L per acre.

[0046] (3) Harvesting: Same as in Example 1.

[0047] Example 7 (Potassium chloride as a salt content regulator - equivalent mass concentration)

[0048] (1) Site selection, land preparation, and planting: Same as in Example 1.

[0049] (2) Field management: Except for replacing the sodium chloride solution with potassium chloride solution (mass concentration of 7.4~22.3 g / L, which is equivalent to the mass concentration of 0.1~0.3 mol / L sodium chloride solution), the other operations are the same as in Example 6.

[0050] (3) Harvesting: Same as in Example 1.

[0051] Control group 1: Water stress-only cultivation

[0052] Except for controlling the relative soil moisture content to 40%~50% and the soil salinity to <0.05%, the other operations are the same as in Example 1.

[0053] Control group 2: Salt stress cultivation only

[0054] Except for controlling the relative soil moisture content at 60%~80% and the soil salinity at 0.2%~0.3%, the other operations are the same as in Example 1.

[0055] Comparative Example 1: Conventional Cultivation

[0056] Except for controlling the relative soil moisture content to 60%~80% and the soil salinity to <0.05%, the other operations are the same as in Example 1.

[0057] Comparative Example 2 (outside the range - low water and high salinity): Soil relative water content 40-45%, salinity 0.2-0.3%, the rest is the same as Example 1.

[0058] Comparative Example 3 (outside the range - high water and high salinity): soil relative water content 50-55%, salinity 0.2-0.3%, the rest is the same as Example 1.

[0059] Test results

[0060] The content of arabinogalactan in the rhizomes of Polygonatum odoratum cultivated in the examples, control group 1, control group 2 and comparative examples was determined by high performance liquid chromatography or phenol-sulfuric acid method. The results are shown in Table 1.

[0061] Table 1 Comparison of arabinogalactan content in Polygonatum under different cultivation conditions Comparative Example 1 60~80% <0.05% 1.47% 1.68% Conventional cultivation Comparative Example 2 40~45% 0.2~0.3% 1.92% 4.68% low water and high salinity Comparative Example 3 50~55% 0.2~0.3% 1.89% 4.27% High water and high salt Control group 1 40~50% <0.05% 1.64% 2.13% Water stress alone Control group 2 60~80% 0.2~0.3% 1.82% 2.69% Salt stress alone Example 1 45~50% 0.2~0.3% 2.05% 4.91% Dual stress of water and salt Example 2 43~45% 0.2~0.3% 1.92% 4.76% Moisture lower limit Example 3 50~52% 0.2~0.3% 1.87% 4.12% Moisture limit Example 4 45~50% 0.18~0.22% 1.93% 4.31% Salt lower limit Example 5 45~50% 0.28~0.32% 1.84% 4.45% Salt limit

[0062] As can be seen from Table 1:

[0063] (1) The conventionally cultivated (comparative) variety had the lowest content of arabinogalactan, which was only 1.68% after 8 months of cultivation.

[0064] (2) Both water stress (control group 1) and salt stress (control group 2) can increase the content of arabinogalactan to a certain extent, reaching 2.13% and 2.69% respectively, which are about 27% and 60% higher than conventional cultivation.

[0065] (3) The effect of water and salt stress (example) is the most significant. After 8 months of planting, the content of arabinogalactan reached 4.91%, which is about 2.9 times higher than conventional cultivation, about 1.3 times higher than water stress alone, and about 0.8 times higher than salt stress alone.

[0066] The effect of dual stress (4.91%) was significantly higher than the linear sum of the effects of single water stress (2.13%) and single salt stress (2.69%) minus the conventional cultivation baseline (1.68%) (2.13% + 2.69% - 1.68% = 3.14%), demonstrating a significant synergistic effect. This indicates a positive interaction between water stress and salt stress, which can synergistically activate secondary metabolic pathways related to arabinogalactan synthesis in Polygonatum sibiricum.

[0067] Data from one month after planting also showed that the effect of dual stress (2.05%) was better than that of single water stress (1.64%) and single salt stress (1.82%), and there was also a synergistic effect.

[0068] In other embodiments of the present invention, potassium chloride can be used instead of sodium chloride as a salt content regulator, with similar effects.

[0069] Table 2 Comparison of sodium chloride and potassium chloride as salt content regulators Example 1 Sodium chloride 0.1~0.3 mol / L 45~50% 0.2~0.3% 4.91% NaCl adjustment Example 6 Potassium chloride 0.1~0.3 mol / L 45~50% 0.2~0.3% 4.72% KCl adjustment (equivalent molar concentration) Example 7 Potassium chloride 7.4~22.3 g / L 45~50% 0.2~0.3% 4.65% KCl adjustment (equivalent mass concentration)

[0070] Table 2 shows that when potassium chloride was used as a salt regulator, under the dual stress of water and salt, the arabinogalactan content in the rhizomes of Polygonatum reached 4.65%–4.72% (dry weight ratio), which was similar to the effect of using sodium chloride as a regulator (4.91%), and significantly higher than the 1.68% in conventional cultivation. This indicates that whether it is sodium chloride or potassium chloride, as long as the soil salinity is controlled within the range of 0.2%–0.3%, it can form a synergistic effect with a relative moisture content of 45%–50%, significantly increasing the arabinogalactan content.

[0071] The physiological basis for the similar effects of potassium chloride and sodium chloride differs: sodium chloride primarily produces similar effects through Na+. + The intervention creates a dual stress of water and salt, strongly stimulating the plant's secondary defense metabolism; while the K in potassium chloride... + As an essential macronutrient for Polygonatum, it mainly plays a role in osmotic regulation and nutrient empowerment at this specific concentration, thereby enhancing the plant's physiological resistance to drought stress and prolonging the continuous synthesis period of arabinogalactan. Regardless of the pathway, both effectively disrupt the carbon metabolism balance under conventional cultivation, achieving the design expectation of this invention to increase the arabinogalactan content to the range of 4.0% to 5.0%.

[0072] In addition, a soil electrical conductivity (EC) sensor can be used to indirectly reflect the salt content by measuring the electrical conductivity of the soil solution. Preferably, a soil water-salt composite sensor (such as the Top Cloud Agriculture TZS-ECW series soil electrical conductivity detector, or the Yunjing Tianhe TH-WSY485 soil temperature, moisture, electrical conductivity, and salt content four-in-one sensor) is used, buried in the root layer of Polygonatum odoratum to simultaneously monitor the relative soil moisture content and electrical conductivity.

[0073] In other embodiments of the present invention, the planting time can be in spring (February to April) and the harvesting time can be in autumn (October to January of the following year), both of which can achieve the technical effects of the present invention.

[0074] This invention's method can be widely applied in existing Polygonatum sibiricum planting bases. It only requires adding a salt sensor and control module to the existing drip irrigation system, and adjusting the salt concentration in the irrigation water is sufficient. This system can interface with existing agricultural IoT platforms to achieve remote monitoring and automated control, demonstrating promising prospects for industrialization.

[0075] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A cultivation method for increasing the content of arabinogalactan in Polygonatum, characterized in that: During the vigorous growth period of Polygonatum, the relative moisture content of the cultivation soil should be controlled at 45%~50%, and the soil salinity should be controlled at 0.2%~0.3%.

2. The cultivation method for increasing the content of arabinogalactan in Polygonatum sibiricum according to claim 1, characterized in that: Soil salinity is regulated by applying neutral salts, including one or more of sodium chloride and potassium chloride.

3. The cultivation method for increasing the content of arabinogalactan in Polygonatum sibiricum according to claim 1, characterized in that: Salt regulation should be applied after the Solomon's seal seedlings emerge and enter the vigorous growth period, so that the soil salt content gradually reaches 0.2% to 0.3% within 30 to 60 days, and is maintained in parallel with the control of relative moisture content of 45% to 50%.

4. The cultivation method for increasing the content of arabinogalactan in Polygonatum sibiricum according to claim 2, characterized in that: By using a drip irrigation system in conjunction with soil moisture and salinity sensors for real-time monitoring, drip irrigation is automatically started when the relative soil moisture content is below 45% and stopped when the relative soil moisture content is above 50%. At the same time, a neutral salt solution is applied through the drip irrigation system to maintain the soil salinity at 0.2% to 0.3%.

5. A rhizome of Polygonatum sibiricum, obtained by the cultivation method described in any one of claims 1 to 4 for increasing the content of arabinogalactan in Polygonatum sibiricum, characterized in that: On a dry weight basis, its arabinogalactan content is 4.0%~5.0%.

6. The rhizome of Polygonatum sibiricum according to claim 5, characterized in that: Polygonatum is the original plant of Polygonatum as defined in the Chinese Pharmacopoeia, including Polygonatum yunnanense, Polygonatum sibiricum, or Polygonatum multiflorum.

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