Method for improving biomass and glycyrrhizic acid content of liquorice

Abstract

The invention discloses a method for improving the biomass and glycyrrhizic acid content of liquorice, belongs to the technical field of plant cultivation, and aims to solve the problem that the glycyrrhizic acid content of artificially cultivated liquorice is low. The method for improving the biomass and glycyrrhizic acid content of the liquorice comprises the step of irrigating liquorice sowing seedlings with a nutrient solution containing gamma-aminobutyric acid. After the nutrient solution containing gamma-aminobutyric acid is used for irrigating the liquorice seeding seedlings, the biomass of the liquorice can be increased, meanwhile, the content of glycyrrhizic acid in the liquorice is effectively increased, and the quality of the artificially cultivated liquorice is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of plant cultivation, and in particular to a method for increasing liquorice biomass and glycyrrhizic acid content. Background Art

[0002] Licorice is one of the important bulk Chinese medicinal materials in my country and an important strategic resource for the development of Chinese medicine. At present, the wild licorice resources in my country are decreasing, and the contradiction between supply and demand of licorice resources is prominent. Optimizing the artificial cultivation of licorice and improving the planting efficiency have become the fundamental ways to enhance the intrinsic resource value of licorice and meet social needs. The output of artificially cultivated licorice in my country has been greatly improved, but its quality is still different from that of wild licorice, mainly because the glycyrrhizic acid content of artificially cultivated licorice is difficult to meet the standards specified in the "Chinese Pharmacopoeia". Licorice extract products have weak international competitiveness. How to increase the biomass and glycyrrhizic acid content of artificially cultivated licorice is an urgent problem to be solved at this stage. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a method for increasing the biomass and glycyrrhizic acid content of licorice, so as to overcome the problem that licorice resources are decreasing and the glycyrrhizic acid content in artificially cultivated licorice is low.

[0004] In a first aspect, the present invention provides a method for increasing the biomass and glycyrrhizic acid content of licorice, characterized in that a nutrient solution containing γ-aminobutyric acid is used to water the licorice seedlings.

[0005] Compared with the prior art, the present invention uses a nutrient solution containing γ-aminobutyric acid to water the licorice seedlings. γ-aminobutyric acid has a regulatory effect on the respiratory metabolism and carbon-nitrogen metabolism of licorice, and is closely related to the carbon-nitrogen balance and distribution of the plant. During the growth of licorice, the accumulation of its biomass and active substances is inseparable from respiratory metabolism and nitrogen metabolism. Nitrogen affects the accumulation of nitrogen-free secondary metabolites such as terpenes and phenols by affecting the carbon-nitrogen nutritional balance in the plant. Therefore, the γ-aminobutyric acid in the nutrient solution can promote the accumulation of licorice biomass and active substance glycyrrhizic acid by regulating the respiratory metabolism of licorice and the carbon-nitrogen balance during the growth of licorice.

[0006] Furthermore, the concentration of γ-aminobutyric acid in the nutrient solution is 1 to 6 mmol / L.

[0007] The above technical solution limits the concentration of γ-aminobutyric acid in the nutrient solution to 1-6 mmol / L. Within this concentration range, γ-aminobutyric acid can better regulate the carbon and nitrogen metabolism and secondary metabolism of licorice, and further promote the accumulation of licorice biomass and active substance glycyrrhizic acid.

[0008] Further, 8 to 10 dm 318 to 22 licorice seedlings are planted in the soil, and when the licorice seedlings grow to two true leaves, the nutrient solution containing gamma-aminobutyric acid is watered once every 12 to 15 days;

[0009] From the 1st to the 30th day, irrigate 1200-1800 mL each time;

[0010] From the 31st to the 90th day, irrigate 1400 to 2000 mL each time;

[0011] After 90 days, 1600 to 2000 mL is watered each time, and the watering ends at 120 days. The above technical scheme further defines the time, frequency and amount of watering the nutrient solution containing γ-aminobutyric acid for watering the licorice seedlings. The inventors found that when the licorice seedlings grow to two true leaves, watering the nutrient solution containing γ-aminobutyric acid to the licorice seedlings at the above-mentioned watering frequency and amount helps the licorice seedlings to better absorb the γ-aminobutyric acid in the nutrient solution, thereby obtaining a better effect of increasing the licorice biomass and glycyrrhizic acid content.

[0012] Further, the nutrient solution comprises the following components in parts by weight per liter of nutrient solution: 430-450 parts of calcium chloride, 490-500 parts of potassium nitrate, 495-510 parts of magnesium sulfate heptahydrate, 130-145 parts of potassium dihydrogen phosphate, 345-360 parts of ammonium sulfate, 4.5-5.5 parts of trace element solution, 2.0-2.5 parts of iron salt solution, and the balance is water. Preferably, the nutrient solution comprises the following components in parts by weight per liter of nutrient solution: 435-445 parts of calcium chloride, 495-500 parts of potassium nitrate, 498-508 parts of magnesium sulfate heptahydrate, 131-141 parts of potassium dihydrogen phosphate, 347-357 parts of ammonium sulfate, 4.95-5.05 parts of trace element solution, and 2.25-2.35 parts of iron salt solution.

[0013] The above technical scheme further defines the composition and ratio of the nutrient solution, which is obtained by improving the Hoagland nutrient solution. It should be emphasized that the composition and configuration method of the iron salt solution refer to the composition and configuration of the iron salt solution in the Hoagland nutrient solution in the prior art. However, the amount of the iron salt solution added to the nutrient solution of the present invention is greatly reduced compared with the amount of the iron salt solution in the Hoagland nutrient solution in the prior art, so that the iron content in the nutrient solution of the present invention is greatly reduced. At the same time, the present invention also increases the content of magnesium in the nutrient solution and reduces the content of potassium in the nutrient solution. After the above optimization, the nutrient solution of the present invention synergizes with γ-aminobutyric acid, which can not only meet the nutrient requirements of licorice, but also optimize the metabolic process of licorice, promote the growth of licorice, and increase the biomass and glycyrrhizic acid content of licorice. In particular, when the preferred composition is selected, the synergistic effect of each component enables the biomass and glycyrrhizic acid content of licorice to reach the optimal value.

[0014] Further, per liter of nutrient solution, the trace element solution includes 2.80-2.90 parts of boric acid, 1.70-1.90 parts of manganese chloride tetrahydrate, 0.20-0.30 parts of zinc sulfate heptahydrate, 0.05-0.07 parts of copper sulfate pentahydrate, 0.025-0.035 parts of sodium molybdate dihydrate, and the balance is water. Preferably, per liter of nutrient solution, the trace element solution includes 2.84-2.88 parts of boric acid, 1.79-1.83 parts of manganese chloride tetrahydrate, 0.20-0.24 parts of zinc sulfate heptahydrate, 0.05-0.07 parts of copper sulfate pentahydrate, 0.028-0.032 parts of sodium molybdate dihydrate, and the balance is water.

[0015] The above technical solution further limits the composition and ratio of the trace element solution in the nutrient solution, reduces the content of copper in the trace element solution, enhances the synergistic effect between the trace element solution and γ-aminobutyric acid, and can further increase the licorice biomass and glycyrrhizic acid content.

[0016] Furthermore, the variety of licorice is Ural Glycyrrhiza uralensis or Glycyrrhiza inflata.

[0017] Furthermore, when the variety of licorice is Glycyrrhiza uralensis, the concentration of γ-aminobutyric acid in the nutrient solution is 1 to 2 mmol / L.

[0018] The above technical scheme further limits the concentration of γ-aminobutyric acid in the nutrient solution when the variety of licorice is Glycyrrhiza uralensis. 1 to 2 mmol / L of γ-aminobutyric acid can better regulate the metabolism of Glycyrrhiza uralensis during its growth and increase the biomass and glycyrrhizic acid content of Glycyrrhiza uralensis.

[0019] Furthermore, when the variety of licorice is Glycyrrhiza inflata, the concentration of γ-aminobutyric acid in the nutrient solution is 2-6 mmol / L.

[0020] The above technical scheme further limits the concentration of γ-aminobutyric acid in the nutrient solution when the licorice variety is Glycyrrhiza inflata. 2-6 mmol / L of γ-aminobutyric acid can better regulate the metabolism of Glycyrrhiza inflata during its growth and increase the biomass and glycyrrhizic acid content of Glycyrrhiza inflata.

[0021] Further, the culture conditions of licorice seeds during germination are:

[0022] The photoperiod is 11-13h, the temperature during the photoperiod is 24℃-26℃, and the humidity is 55-65%rh;

[0023] The dark cycle is 11 to 13 hours, the temperature during the dark cycle is 19℃ to 21℃, and the humidity is 35 to 45% rh.

[0024] The above technical solution further defines the culture conditions during the germination period of licorice seeds. The above specific culture conditions can promote the smooth germination and initial growth of licorice seeds, and improve the germination rate of seeds and the health status of seedlings.

[0025] Further, when the licorice seedlings grow to two true leaves, the culture conditions are:

[0026] The photoperiod is 13-15h, the temperature during the photoperiod is 24℃-26℃, and the humidity is 55-65% rh;

[0027] The dark cycle is 9 to 11 hours, the temperature during the dark cycle is 19℃ to 21℃, and the humidity is 35 to 45% rh;

[0028] 8~10dm 3 18 to 22 licorice seedlings are planted in the soil. The licorice seedlings are watered with a nutrient solution containing gamma-aminobutyric acid and water is supplemented every 6 to 8 days, with 1500 to 2000 mL supplemented each time.

[0029] The above technical scheme further limits the culture conditions when the licorice seedlings grow to two true leaves. The above specific culture conditions can ensure the healthy growth of the licorice seedlings and enable the licorice seedlings to better absorb various nutrients in the nutrient solution containing γ-aminobutyric acid, thereby further increasing the biomass and glycyrrhizic acid content of the licorice. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] It should be understood that the raw materials used in the following examples are all commercially available raw materials unless otherwise specified.

[0032] Example 1

[0033] The seeds of Glycyrrhiza uralensis and Glycyrrhiza inflata were soaked in deionized water for 24 hours before sowing, rinsed, and sown in polyethylene plastic pots (upper diameter 16 cm, lower diameter 13 cm, height 17.5 cm) for cultivation, each polyethylene plastic pot was filled with 2.6 kg of sandy soil that had been sieved through a square sieve with a pore size of 5 mm. The seeds of Glycyrrhiza uralensis and Glycyrrhiza inflata were wild seeds collected from Bayinwusu, Inner Mongolia and Bayingol Prefecture, Xinjiang, respectively.

[0034] After sowing, the seeds were placed in a laboratory with an LED light environment for cultivation. The cultivation conditions for the germination period of licorice seeds were as follows: a light cycle of 12 hours, a temperature of 25°C, and a humidity of 60% rh; a dark cycle of 12 hours, a temperature of 20°C, and a humidity of 40% rh.

[0035] When the licorice seedlings grow to two true leaves, 15 seedlings are left in each pot. The culture conditions are: light cycle 14h, temperature 25℃, humidity 60% rh; dark cycle 10h, temperature 20℃, humidity 40% rh.

[0036] At the same time, when the licorice seedlings grow to two true leaves, water them with a nutrient solution containing gamma-aminobutyric acid once every 13 days; 1500 mL of nutrient solution is used each time from the 1st to the 30th day; 1700 mL of nutrient solution is used each time from the 31st to the 90th day; after 90 days, 1900 mL of nutrient solution is used each time until the 120th day. While watering the licorice seedlings with the nutrient solution containing gamma-aminobutyric acid, water is added once every 7 days, 1500 mL of nutrient solution is added each time.

[0037] When watering the Ural Glycyrrhiza uralensis seedlings, the concentration of γ-aminobutyric acid in the nutrient solution was 1.5mmol / L. When watering the Glycyrrhiza inflata seedlings, the concentration of γ-aminobutyric acid in the nutrient solution was 4mmol / L.

[0038] Based on one liter of nutrient solution, the nutrient solution also includes the following components: 440 mg of calcium chloride, 497 mg of potassium nitrate, 503 mg of magnesium sulfate heptahydrate, 136 mg of potassium dihydrogen phosphate, 352 mg of ammonium sulfate, 5.00 mg of trace element solution, and 2.30 mg of EDTA-Fe solution. The preparation method of EDTA-Fe solution is as follows: weigh 2.785 g of ferrous sulfate heptahydrate, dissolve it with 80 mL of distilled water, then heat to boil, and after boiling, add the weighed 3.725 g of Na2-EDTA. Pay special attention to stirring while adding Na2-EDTA. Finally, cool to room temperature and transfer to a 500 ml volumetric flask to make up the volume.

[0039] Based on one liter of nutrient solution, the trace element solution includes 2.86 mg of boric acid, 1.81 mg of manganese chloride tetrahydrate, 0.22 mg of zinc sulfate heptahydrate, 0.06 mg of copper sulfate pentahydrate, and 0.030 mg of sodium molybdate dihydrate.

[0040] Example 2

[0041] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, and the differences were as follows:

[0042] After sowing, the seeds were placed in a laboratory under LED light environment for cultivation. The cultivation conditions for licorice seeds during germination were as follows: light cycle 11h, temperature 25°C, humidity 60% rh; dark cycle 13h, temperature 20°C, humidity 40% rh.

[0043] When the licorice seedlings grow to two true leaves, 15 seedlings are left in each pot. The culture conditions are: light cycle 13h, temperature 25℃, humidity 60% rh; dark cycle 11h, temperature 20℃, humidity 40% rh.

[0044] At the same time, when the licorice seedlings grow to two true leaves, water them with a nutrient solution containing gamma-aminobutyric acid once every 12 days; 1200 mL of nutrient solution is used each time from the 1st to the 30th day; 1400 mL of nutrient solution is used each time from the 31st to the 90th day; after 90 days, 1600 mL of nutrient solution is used each time until the 120th day. While watering the licorice seedlings with the nutrient solution containing gamma-aminobutyric acid, water is added every 6 days, 1700 mL of nutrient solution is added each time.

[0045] When watering the Ural Glycyrrhiza uralensis seedlings, the concentration of γ-aminobutyric acid in the nutrient solution was 1 mmol / L. When watering the Glycyrrhiza inflata seedlings, the concentration of γ-aminobutyric acid in the nutrient solution was 2 mmol / L.

[0046] Based on one liter of nutrient solution, the nutrient solution further includes the following components: 435 mg of calcium chloride, 495 mg of potassium nitrate, 498 mg of magnesium sulfate heptahydrate, 131 mg of potassium dihydrogen phosphate, 347 mg of ammonium sulfate, 4.95 mg of trace element solution, and 2.25 mg of EDTA-Fe solution, wherein the preparation method of EDTA-Fe solution refers to Example 1.

[0047] Based on one liter of nutrient solution, the trace element solution includes 2.84 mg of boric acid, 1.79 mg of manganese chloride tetrahydrate, 0.20 mg of zinc sulfate heptahydrate, 0.05 mg of copper sulfate pentahydrate, and 0.028 mg of sodium molybdate dihydrate.

[0048] Example 3

[0049] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, with the following differences: after sowing, they were placed in a laboratory under LED light environment for cultivation, and the cultivation conditions for licorice seeds during germination were: light cycle 13h, temperature 25°C, humidity 60% rh; dark cycle 11h, temperature 20°C, humidity 40% rh.

[0050] When the licorice seedlings grow to two true leaves, 15 seedlings are left in each pot. The culture conditions are: light cycle 15h, temperature 25℃, humidity 60% rh; dark cycle 9h, temperature 20℃, humidity 40% rh.

[0051] At the same time, when the licorice seedlings grow to two true leaves, water them with a nutrient solution containing gamma-aminobutyric acid once every 14 days; from the 1st to the 30th day, water them with 1800 mL each time; from the 31st to the 90th day, water them with 2000 mL each time; after 90 days, water them with 2000 mL each time until the 120th day. While watering the licorice seedlings with the nutrient solution containing gamma-aminobutyric acid, water is supplemented every 8 days, with 2000 mL each time.

[0052] When watering the Ural Glycyrrhiza uralensis seedlings, the concentration of γ-aminobutyric acid in the nutrient solution was 2 mmol / L. When watering the Glycyrrhiza inflata seedlings, the concentration of γ-aminobutyric acid in the nutrient solution was 6 mmol / L.

[0053] Based on one liter of nutrient solution, the nutrient solution further includes the following components: 445 mg of calcium chloride, 500 mg of potassium nitrate, 508 mg of magnesium sulfate heptahydrate, 141 mg of potassium dihydrogen phosphate, 357 mg of ammonium sulfate, 5.05 mg of trace element solution, and 2.35 mg of EDTA-Fe solution, wherein the preparation method of EDTA-Fe solution refers to Example 1.

[0054] Based on one liter of nutrient solution, the trace element solution includes 2.88 mg of boric acid, 1.83 mg of manganese chloride tetrahydrate, 0.24 mg of zinc sulfate heptahydrate, 0.07 mg of copper sulfate pentahydrate, and 0.032 mg of sodium molybdate dihydrate.

[0055] Comparative Example 1

[0056] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, except that an equal amount of γ-aminobutyric acid in the nutrient solution was replaced by water.

[0057] Comparative Example 2

[0058] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, except that the concentration of γ-aminobutyric acid in the nutrient solution was 0.5 mmol / L when watering the seedlings of Glycyrrhiza uralensis and 1 mmol / L when watering the seedlings of Glycyrrhiza inflata.

[0059] Comparative Example 3

[0060] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, except that when watering the seedlings of Glycyrrhiza uralensis, the concentration of γ-aminobutyric acid in the nutrient solution was 3 mmol / L. When watering the seedlings of Glycyrrhiza inflata, the concentration of γ-aminobutyric acid in the nutrient solution was 7 mmol / L.

[0061] Comparative Example 4

[0062] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, except that the nutrient solution containing γ-aminobutyric acid was replaced with ordinary Hoagland nutrient solution that did not contain γ-aminobutyric acid.

[0063] Comparative Example 5

[0064] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, except that an equal amount of the nutrient solution containing γ-aminobutyric acid was replaced with an ordinary Hoagland nutrient solution containing γ-aminobutyric acid.

[0065] Comparative Example 6

[0066] Glycyrrhiza uralensis and Glycyrrhiza inflata were cultivated according to the method of Example 1, except that when the licorice seedlings grew to two true leaves, they were watered with nutrient solution containing gamma-aminobutyric acid once every 13 days, with 1700 mL of nutrient solution each time, until 120 days.

[0067] Test Case

[0068] The aboveground fresh weight, root fresh weight and glycyrrhizic acid content of Glycyrrhiza uralensis and Glycyrrhiza inflata in the above Examples 1 to 3 and Comparative Examples 1 to 5 were respectively tested, and the results are shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] From the above test results, it can be seen that in Comparative Example 1, the γ-aminobutyric acid in the nutrient solution is replaced with water in an equal amount, in Comparative Example 4, the nutrient solution containing γ-aminobutyric acid is replaced with an ordinary Hogland nutrient solution without γ-aminobutyric acid, and in Comparative Example 5, the nutrient solution containing γ-aminobutyric acid is replaced with an ordinary Hogland nutrient solution containing γ-aminobutyric acid in an equal amount. After that, the root fresh weight and glycyrrhizic acid content of Ural Glycyrrhiza and Glycyrrhiza inflata are reduced, indicating that the specific concentration of γ-aminobutyric acid in the nutrient solution of the present invention can further increase the root fresh weight and glycyrrhizic acid content of licorice. After Comparative Examples 2 and 3 changed the concentration of γ-aminobutyric acid in the nutrient solution, the root fresh weight and glycyrrhizic acid content of Ural Glycyrrhiza and Glycyrrhiza inflata are reduced, indicating that the specific concentration of γ-aminobutyric acid in the nutrient solution of the present invention can further increase the root fresh weight and glycyrrhizic acid content of licorice. After the irrigation method of the nutrient solution containing γ-aminobutyric acid was changed in Comparative Example 6, the root fresh weight and glycyrrhizic acid content of Glycyrrhiza uralensis and Glycyrrhiza inflata were reduced, indicating that the present invention can further increase the root fresh weight and glycyrrhizic acid content of Glycyrrhiza uralensis by irrigating the nutrient solution containing γ-aminobutyric acid to the licorice seedlings in a specific manner.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for increasing the biomass and glycyrrhizic acid content of liquorice, characterized in that: The nutrient solution containing γ-aminobutyric acid was used to water the licorice seedlings.

2. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 1, characterized in that: The concentration of gamma-aminobutyric acid in the nutrient solution is 1-6 mmol / L.

3. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 1, characterized in that: 8~10dm 3 Plant 18 to 22 licorice seedlings in the soil, and when the licorice seedlings grow to two true leaves, water them with the nutrient solution containing gamma-aminobutyric acid once every 12 to 15 days; From the 1st to the 30th day, irrigate 1200-1800 mL each time; From the 31st to the 90th day, irrigate 1400 to 2000 mL each time; After 90 days, water 1600-2000 mL each time, and end after 120 days.

4. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 1, characterized in that: The nutrient solution comprises the following components in parts by weight per liter of nutrient solution: 430-450 parts of calcium chloride, 490-500 parts of potassium nitrate, 495-510 parts of magnesium sulfate heptahydrate, 130-145 parts of potassium dihydrogen phosphate, 345-360 parts of ammonium sulfate, 4.5-5.5 parts of trace element solution, 2.0-2.5 parts of iron salt solution, and the balance is water.

5. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 4, characterized in that: Calculated per liter of nutrient solution, the trace element solution includes 2.80-2.90 parts of boric acid, 1.70-1.90 parts of manganese chloride tetrahydrate, 0.20-0.30 parts of zinc sulfate heptahydrate, 0.05-0.07 parts of copper sulfate pentahydrate, 0.025-0.035 parts of sodium molybdate dihydrate, and the balance is water.

6. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 1, characterized in that: The type of the liquorice is Glycyrrhiza uralensis or Glycyrrhiza inflata.

7. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 6, characterized in that: When the type of licorice is Glycyrrhiza uralensis, the concentration of γ-aminobutyric acid in the nutrient solution is 1-2 mmol / L.

8. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 6, characterized in that: When the type of licorice is Glycyrrhiza inflata, the concentration of γ-aminobutyric acid in the nutrient solution is 2-6 mmol / L.

9. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 1, characterized in that: The culture conditions for licorice seed germination are: The photoperiod is 11 to 13 hours, the temperature during the photoperiod is 24° C. to 26° C., and the humidity is 55 to 65% rh; The dark cycle is 11 to 13 hours, the temperature during the dark cycle is 19° C. to 21° C., and the humidity is 35 to 45% rh.

10. The method for increasing the biomass and glycyrrhizic acid content of liquorice according to claim 1, characterized in that: When the licorice seedlings grow to two true leaves, the culture conditions are: The photoperiod is 13 to 15 hours, the temperature during the photoperiod is 24° C. to 26° C., and the humidity is 55 to 65% rh; The dark cycle is 9 to 11 hours, the temperature during the dark cycle is 19° C. to 21° C., and the humidity is 35 to 45% rh; 8~10dm 3 18 to 22 licorice seedlings are planted in the soil. While watering the licorice seedlings with the nutrient solution containing gamma-aminobutyric acid, water is supplemented every 6 to 8 days, with 1500 to 2000 mL supplemented each time.

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