Application of nano zinc oxide in improving biomass and active ingredient content of liquorice

Abstract

The invention discloses application of nano-zinc oxide in improving biomass and active ingredient content of liquorice, relates to the technical field of plant cultivation, and aims to improve biomass and active ingredient content of liquorice. By applying nano zinc oxide externally, the plant height, root length and dry matter accumulation amount of the liquorice can be remarkably increased, and the biomass of the liquorice is increased; meanwhile, synthesis and accumulation of main active ingredients such as glycyrrhizic acid and liquiritin are effectively promoted; meanwhile, the physiological status of liquorice under stress conditions such as salt stress can be improved, the stress resistance is enhanced, and the in-vivo ion balance and the redox steady state are regulated, so that the growth and quality of liquorice are synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of plant cultivation technology, and in particular to the application of nano zinc oxide in increasing the biomass and active ingredient content of licorice. Background Technology

[0002] Among various abiotic stresses such as drought, salinity, extreme temperatures, heavy metals, and organic pollutants, soil salinization is considered one of the most destructive factors, becoming a major constraint on agricultural productivity and global food security. Planting salt-tolerant and economically valuable plant varieties in saline-alkali lands is considered an efficient and practical strategy for the sustainable utilization of saline-alkali land resources. Licorice (Glycyrrhiza uralensis Fisch.) is a perennial leguminous medicinal plant with extremely high commercial value. Its roots and rhizomes are rich in triterpenoid saponins, flavonoids, and other bioactive components, possessing various pharmacological activities such as immunomodulation and antiviral activity. Licorice is widely used as a traditional medicine in both Eastern and Western countries, and also has extensive applications in the food, light industry, and cosmetics sectors. With increasing global health awareness and reliance on natural medicines, the demand for licorice has grown rapidly, leading to the depletion of wild resources, making artificial cultivation the primary supply method.

[0003] Therefore, there is an urgent need to provide a method to increase the biomass and content of active ingredients in licorice. Summary of the Invention

[0004] The purpose of this invention is to provide an application of nano zinc oxide in increasing the biomass and active ingredient content of licorice, thereby increasing the biomass and active ingredient content of licorice.

[0005] To achieve the above objectives, the first aspect of the present invention provides the application of nano zinc oxide in increasing the biomass and active ingredient content of licorice.

[0006] Compared with existing technologies, this invention discovers a novel application of nano-zinc oxide, which can increase the biomass and active ingredient content of licorice. By applying nano-zinc oxide exogenously, the plant height, root length, and dry matter accumulation of licorice can be significantly increased, thereby increasing licorice biomass. Simultaneously, it effectively promotes the synthesis and accumulation of major active ingredients such as glycyrrhizic acid and glycyrrhizin; furthermore, it can improve the physiological state of licorice under adverse conditions such as salt stress, enhance its stress resistance, and regulate its ion balance and redox homeostasis, thus achieving a synergistic improvement in licorice growth and quality.

[0007] Furthermore, the particle size of the nano zinc oxide is 1-50 nm.

[0008] In this invention, when the particle size of nano zinc oxide meets the above-mentioned range, it can further increase the biomass and active ingredient content of licorice.

[0009] Furthermore, the nano zinc oxide is added as a zinc source to water or nutrient solution for irrigation and / or spraying of licorice during its growth period.

[0010] In this invention, the above-mentioned method for applying zinc fertilizer is not only simple to operate and requires a low amount of fertilizer, but it is also environmentally friendly. It can reduce the amount of traditional zinc fertilizer used, avoid waste of zinc and environmental risks, and is suitable for promotion and application in the standardized cultivation of medicinal licorice.

[0011] Furthermore, the effective concentration of nano zinc oxide in the water or nutrient solution is 5-60 mg / L.

[0012] In this invention, when the effective concentration of nano zinc oxide in water or nutrient solution meets the above-mentioned range, the biomass and active ingredient content of licorice can be further increased.

[0013] Furthermore, the watering is performed 3-6 times; the sprinkler irrigation is performed 2-6 times.

[0014] Furthermore, based on the land area of ​​licorice, the effective dosage of the nano-zinc oxide is (0.5-5) g / m². 2 .

[0015] In this invention, when irrigation or sprinkler irrigation conditions, or the effective dosage of nano zinc oxide, meet the above-mentioned range, the biomass and active ingredient content of licorice can be further increased.

[0016] Furthermore, the improvement of licorice biomass includes: Increase the plant height and root length of licorice; Increase the dry weight of both the above-ground and underground parts of licorice; Increase the root-to-shoot ratio of licorice.

[0017] Furthermore, the active ingredients include glycyrrhizic acid and / or glycyrrhizin.

[0018] Furthermore, the total flavonoid concentration, based on the dry weight of the licorice root, is greater than or equal to 40 mg / g.

[0019] Furthermore, based on the dry weight of the underground part of the licorice, the concentration of glycyrrhizic acid is greater than or equal to 2.5 mg / g, and the concentration of glycyrrhizin is greater than or equal to 0.7 mg / g.

[0020] Furthermore, the nano-zinc oxide is used to increase the biomass and active ingredient content of licorice under salt stress conditions; the salt stress conditions include: the sodium chloride concentration in the water or nutrient solution containing nano-zinc oxide is 130-180 mmol / L. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] The first aspect of this invention provides the application of nano-zinc oxide in increasing the biomass and active ingredient content of licorice.

[0023] This invention discovers a novel application of nano-zinc oxide, which can increase the biomass and active ingredient content of licorice. By applying nano-zinc oxide exogenously, the plant height, root length, and dry matter accumulation of licorice can be significantly increased, thus increasing licorice biomass. Simultaneously, it effectively promotes the synthesis and accumulation of major active ingredients such as glycyrrhizic acid and glycyrrhizin; furthermore, it can improve the physiological state of licorice under adverse conditions such as salt stress, enhance its resistance, and regulate its ion balance and redox homeostasis, thereby achieving a synergistic improvement in licorice growth and quality.

[0024] In some embodiments, the particle size of the nano zinc oxide is 1-50 nm.

[0025] By adopting the above technical solution, when the particle size of nano zinc oxide meets the above range, the biomass and active ingredient content of licorice can be further improved.

[0026] For example, the particle size of the nano zinc oxide can be 1nm, 2nm, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, or a range consisting of any two of the aforementioned values.

[0027] Preferably, the particle size of the nano zinc oxide is 2-12 nm.

[0028] In some embodiments, the nano zinc oxide is added as a zinc source to water or nutrient solution for irrigation and / or spraying of licorice during its growth period.

[0029] The above-mentioned technical solution and method for applying zinc fertilizer is not only simple to operate and requires low dosage, but also environmentally friendly. It can reduce the amount of traditional zinc fertilizer used, avoid zinc waste and environmental risks, and is suitable for promotion and application in the standardized cultivation of medicinal licorice.

[0030] According to the present invention, there are no special limitations on the specific components of the nutrient solution; any nutrient solution conventional in the art that can be directly used for watering and / or spraying licorice can be used. The method for dispersing nano-zinc oxide in water or nutrient solution according to the present invention aims to ensure uniform dispersion of the nano-zinc oxide. For example, after the nano-zinc oxide is added to the water or nutrient solution as a zinc source, it can be ultrasonicated for 15-30 minutes at a frequency of 40-70 Hz to ensure uniform dispersion. During watering and / or spraying, the solution can be stirred to prevent the nano-zinc oxide from agglomerating.

[0031] In some embodiments, the effective concentration of nano zinc oxide in the water or nutrient solution is 5-60 mg / L.

[0032] By adopting the above technical solution, when the effective concentration of nano zinc oxide in water or nutrient solution meets the above range, the biomass and active ingredient content of licorice can be further improved.

[0033] For example, the effective concentration of nano zinc oxide in the water or nutrient solution can be 5 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, or a range consisting of any two of the aforementioned values.

[0034] Preferably, the concentration of nano-zinc oxide in the water or nutrient solution is 10-40 mg / L. More preferably, the concentration of nano-zinc oxide in the water or nutrient solution is 15-25 mg / L.

[0035] In some embodiments, the watering is performed 3-6 times; the sprinkler irrigation is performed 2-6 times.

[0036] In some embodiments, the effective amount of nano-zinc oxide, based on the land area of ​​licorice, is (0.5-5) g / m². 2 .

[0037] By adopting the above technical solution, when irrigation or sprinkler irrigation conditions, or when the effective dosage of nano zinc oxide meets the above range, the biomass and active ingredient content of licorice can be further improved.

[0038] Preferably, the effective amount of nano-zinc oxide, calculated based on the land area of ​​licorice, is (1.5-2.5) g / m². 2 .

[0039] According to the present invention, there is no particular limitation on the time interval of irrigation and / or sprinkler irrigation, as long as the effective concentration and / or effective dosage of nano zinc oxide are met. For example, the time interval of irrigation and / or sprinkler irrigation can be 3-15 days.

[0040] In some embodiments, increasing the biomass of licorice includes: Increase the plant height and root length of licorice; Increase the dry weight of both the above-ground and underground parts of licorice; Increase the root-to-shoot ratio of licorice.

[0041] In some embodiments, the root length growth rate of licorice treated with nano zinc oxide is 12-30%, preferably 20-30%, compared with licorice without nano zinc oxide.

[0042] In some embodiments, under salt stress conditions, the root length growth rate of licorice treated with nano-zinc oxide is 8-35%, preferably 20-35%, compared with licorice without nano-zinc oxide.

[0043] In some embodiments, the plant height growth rate of licorice treated with nano zinc oxide is 5-18%, preferably 10-18%, compared with licorice without nano zinc oxide.

[0044] In some embodiments, under salt stress conditions, the plant height growth rate of licorice treated with nano-zinc oxide is 4-18%, preferably 10-18%, compared with licorice without nano-zinc oxide.

[0045] In some embodiments, compared with licorice without nano zinc oxide, the aboveground dry weight increase rate of licorice with nano zinc oxide is 7-40%, preferably 20-40%; and the underground dry weight increase rate of licorice is 19-110%, preferably 50-110%.

[0046] In some embodiments, under salt stress conditions, compared with licorice without nano-zinc oxide, the aboveground dry weight increase rate of licorice with nano-zinc oxide is 4-35%, preferably 20-35%; and the underground dry weight increase rate of licorice is 14-70%, preferably 30-70%.

[0047] In some embodiments, the root-to-shoot ratio of the licorice is greater than or equal to 0.55; preferably greater than or equal to 0.7.

[0048] In some embodiments, the active ingredient includes glycyrrhizic acid and / or glycyrrhizin.

[0049] In some embodiments, the concentration of total flavonoids, based on the dry weight of the licorice root, is greater than or equal to 40 mg / g.

[0050] Preferably, the concentration of total flavonoids, based on the dry weight of the licorice root, is 40-60 mg / g, more preferably 50-60 mg / g.

[0051] In some embodiments, the total flavonoid concentration of licorice treated with nano zinc oxide increased by 20-50%, preferably 30-50%, compared with licorice not treated with nano zinc oxide.

[0052] In some embodiments, under salt stress conditions, the total flavonoid concentration of licorice treated with nano-zinc oxide increased by 10-50%, preferably 30-50%, compared with licorice not treated with nano-zinc oxide.

[0053] In some embodiments, the concentration of glycyrrhizic acid is greater than or equal to 2.5 mg / g and the concentration of glycyrrhizin is greater than or equal to 0.7 mg / g, based on the dry weight of the underground part of the licorice.

[0054] Preferably, the concentration of glycyrrhizic acid is 2.5-11 mg / g, more preferably 7.5-11 mg / g, based on the dry weight of the underground part of the licorice; and the concentration of glycyrrhizin is 0.7-4 mg / g, more preferably 2.7-4 mg / g.

[0055] In some embodiments, compared with licorice without nano zinc oxide, the glycyrrhizin concentration of licorice treated with nano zinc oxide increases by 20-60%, preferably 35-60%, based on the dry weight of the underground part of the licorice; and the glycyrrhizin content per plant increases by 55-250%, preferably 150-250%.

[0056] According to the present invention, the glycyrrhizin content per plant refers to the total amount of glycyrrhizin contained in the underground part of a single glycyrrhiza plant.

[0057] In some embodiments, under salt stress conditions, compared with licorice without nano-zinc oxide application, the glycyrrhizin concentration of licorice treated with nano-zinc oxide increases by 5-35% (preferably 25-35%) based on the dry weight of the underground part of the licorice; the glycyrrhizin content per plant increases by 30-150% (preferably 70-150%).

[0058] In some embodiments, compared with licorice without nano zinc oxide application, the glycyrrhizic acid concentration of licorice treated with nano zinc oxide increases by 40-90%, preferably 70-90%, based on the dry weight of the underground part of the licorice; and the glycyrrhizic acid content per plant increases by 65-300%, preferably 150-300%.

[0059] According to the present invention, the glycyrrhizic acid content per plant refers to the total amount of glycyrrhizic acid contained in the underground part of a single licorice plant.

[0060] In some embodiments, under salt stress conditions, compared with licorice without nano-zinc oxide application, the glycyrrhizic acid concentration of licorice treated with nano-zinc oxide increases by 14-45%, preferably 28-45%, based on the dry weight of the underground part of the licorice; and the glycyrrhizic acid content per plant increases by 50-200%, preferably 100-200%.

[0061] According to the present invention, licorice can be grown in a natural environment, therefore there are no special limitations on the cultivation conditions. For example, alternating photoperiod and dark period cultivation can be used, with the following cultivation conditions: The photoperiod duration is 12-14 hours, the temperature is 22-26°C, and the relative humidity is 55-60%rh. The dark period lasts for 10-12 hours, with a temperature of 13-18°C and a relative humidity of 55-60%rh.

[0062] In some embodiments, the nano-zinc oxide is used to increase the biomass and active ingredient content of licorice under salt stress conditions; the salt stress conditions include: the sodium chloride concentration in the water or nutrient solution containing nano-zinc oxide is 130-180 mmol / L.

[0063] To better illustrate the technical solution of the present invention, the following specific embodiments are also provided.

[0064] Unless otherwise specified, all raw materials used in the examples and comparative examples were obtained commercially.

[0065] Example

[0066] The selected licorice seeds were collected from Yanchi County, Ningxia, China. The licorice seeds were washed three times with ultrapure water, then disinfected sequentially with 75% ethanol for 30 seconds, followed by disinfection with 5% sodium hypochlorite solution for 10 minutes, and finally rinsed three times with ultrapure water. The seeds were then placed in petri dishes to germinate. When the seedlings reached approximately 2 cm in height, they were transplanted into pots filled with farmland soil (pots with a top diameter of 15.5 cm, a bottom diameter of 11 cm, and a height of 18.6 cm, with approximately 3 cubic meters of soil in each pot). The soil area is approximately 0.019m². 3 The density was 20 plants per pot. The plants were exposed to light for 14 hours at 24℃ and 60% relative humidity, and then kept in darkness for 10 hours at 16℃ and 60% relative humidity. This light-dark cycle was repeated.

[0067] Licorice seedlings were randomly divided into 8 experimental groups, with 20 licorice seedlings in each group, and each experimental group was repeated three times.

[0068] CK group: control group, irrigated with ultrapure water once every 4 days; Group Zn1: Irrigation was carried out using ultrapure water with a concentration of 10 mg / L nano-zinc oxide. The effective dosage of nano-zinc oxide was 1... The nano zinc oxide was applied in six separate applications, once every four days. Group Zn2: Irrigation was carried out using ultrapure water with a concentration of 20 mg / L nano-zinc oxide. The effective dosage of nano-zinc oxide was 2.12. The nano zinc oxide was applied in six separate applications, once every four days. Group Zn3: Irrigation was carried out using ultrapure water with a concentration of 40 mg / L nano-zinc oxide. The effective dosage of nano-zinc oxide was 4.24 mg / L. The nano zinc oxide was applied in six separate applications, once every four days. Group M: Irrigated with ultrapure sodium chloride water with a concentration of 160 mmol / L; irrigated once every 4 days; Group MZn1: The sodium chloride concentration in the irrigation water was 160 mmol / L, the nano zinc oxide concentration was 10 mg / L, and the effective dosage of nano zinc oxide was 1. The nano zinc oxide was applied in six separate applications, once every four days. Group MZn2: The sodium chloride concentration in the irrigation water was 160 mmol / L, the nano zinc oxide concentration was 20 mg / L, and the effective dosage of nano zinc oxide was 2.12 mg / L. The nano zinc oxide was applied in six separate applications, once every four days. Group MZn3: The sodium chloride concentration in the irrigation water was 160 mmol / L, the nano zinc oxide concentration was 40 mg / L, and the effective dosage of nano zinc oxide was 4.24 mg / L. The nano zinc oxide was applied in six separate applications, once every four days. The nano zinc oxide used in the above-mentioned experimental groups has a particle size range of 2-12 nm and an average particle size of 6.5 nm. After the nano zinc oxide is added to water or nutrient solution as a zinc source, it is ultrasonicated at 60 Hz for 20 min to make the nano zinc oxide uniformly dispersed in the water. During the irrigation process, the irrigation solution is stirred to avoid the agglomeration of nano zinc oxide.

[0069] On day 30, samples of licorice were taken and tested according to the following method.

[0070] (1) Test methods for root length, plant height, aboveground dry weight, underground dry weight, and root-to-shoot ratio: Clean the licorice plant samples and absorb excess water with filter paper. Measure the plant height and root length directly using a steel ruler. Separate the aboveground and underground parts with scissors, then place the aboveground and underground parts into paper bags and dry them at 65℃ for 48 hours until constant weight. Weigh them separately using an electronic scale to obtain the aboveground and underground dry weights of the licorice. The root-to-shoot ratio is the ratio of underground dry weight to aboveground dry weight. All indicators were measured repeatedly 15 times. The test results are shown in Tables 2 and 3.

[0071] (2) The concentrations of glycyrrhizin and glycyrrhizic acid in the underground parts of licorice, as well as the content of glycyrrhizin and glycyrrhizic acid per plant, were tested by high performance liquid chromatography. The specific test methods included: Chromatographic conditions: Octadecylsilane-bonded silica gel was used as the stationary phase; acetonitrile was used as mobile phase A, and 0.05% phosphoric acid solution was used as mobile phase B, with gradient elution performed according to the specifications in Table 1; the flow rate was 1.0 mL / min, and the detection wavelength was 237 nm. Table 1 Preparation of standard working solutions: Accurately weigh 1.22 mg of glycyrrhizic acid standard and 1.00 mg of glycyrrhizin standard, and transfer them to 10 mL volumetric flasks respectively. Dilute to volume with 70% ethanol to obtain glycyrrhizic acid solution and glycyrrhizin solution respectively. Transfer 2.0 mL of glycyrrhizic acid solution and 2.0 mL of glycyrrhizin solution to 10 mL volumetric flasks respectively, and dilute to volume with 70% ethanol to prepare glycyrrhizic acid standard stock solution and glycyrrhizin standard stock solution respectively. Transfer appropriate amounts of glycyrrhizic acid standard stock solution and glycyrrhizin standard stock solution to 5 mL volumetric flasks respectively, and dilute with 70% ethanol to prepare glycyrrhizin standard working solutions and glycyrrhizic acid standard working solutions with concentration as the abscissa (x) and peak area as the ordinate (y). Filter through a 0.22 μm microporous membrane and store in a liquid chromatography vial. Measure under the above liquid chromatography conditions, and plot a standard curve with concentration as the abscissa (x) and peak area as the ordinate (y). Preparation of the test solution: Three underground part samples were randomly selected from each experimental group, dried and pulverized; about 0.2 g of sample powder (passed through a No. 3 sieve) was accurately weighed, placed in a stoppered conical flask, 100 ml of 70% ethanol was accurately added, the flask was sealed, the weight was measured, and the sample was sonicated (frequency 40 kHz) for 30 minutes. After cooling, the weight was measured again, and the weight loss was made up with 70% ethanol. The sample was shaken well, filtered, and the filtrate was collected to obtain the test solution; the solution was determined according to the above liquid chromatography conditions. Quantitative method: A linear regression equation was established based on the peak area and concentration of the standard working solution. The concentration of the test solution was calculated using the linear regression equation, and the concentrations of glycyrrhizic acid and glycyrrhizin in the lower part of licorice were calculated according to the following formula. X = (C × V × K) / (m × 1000) Equation (1); In formula (1): X is the concentration of glycyrrhizic acid or glycyrrhizin in the lower part of licorice, in mg / g; C represents the concentration of glycyrrhizic acid or glycyrrhizin measured in the test solution, in μg / mL; V represents the constant volume, in mL; K is the dilution factor of the sample; m represents the accurate amount of sample powder weighed, in grams; 1000 is the conversion factor for milliliters (mL) to liters (L); The calculation results were retained to three significant figures, and the glycyrrhizin and glycyrrhizic acid contents per plant were calculated based on the mass of the underground parts of licorice. The test results are shown in Tables 4 to 7.

[0072] (3) The method for detecting the total flavonoid concentration in licorice root is as follows: Approximately 0.03 g of dried licorice root sample was randomly weighed, and 1.5 mL of 60% ethanol was added. The sample was extracted by shaking at 60°C for 2 h. After centrifugation at 12000 rpm for 10 min at 25°C, the supernatant was collected for analysis. Sample testing: Total flavonoids detection based on The total flavonoid concentration was determined by a colorimetric method. The concentration of total flavonoids in the supernatant was detected using a kit from Jiangsu Aidisheng Biotechnology Co., Ltd., following the instructions in the kit's package insert. The test results are shown in Table 8.

[0073] Table 2. Root length, plant height, aboveground dry weight, underground dry weight, root-to-shoot ratio, and growth rate of licorice compared to the control group. Table 3. Root length, plant height, aboveground dry weight, underground dry weight, root-to-shoot ratio, and growth rate compared to group M of licorice. Table 4. Glycyrrhizin concentration in the underground parts of licorice, glycyrrhizin content per plant, and growth rate compared to the control group. Table 5. Glycyrrhizin concentration in the underground parts of licorice, glycyrrhizin content per plant, and growth rate compared to group M. Table 6. Glycyrrhizic acid concentration in the underground parts of licorice, glycyrrhizic acid content per plant, and growth rate compared to the control group. Table 7. Glycyrrhizic acid concentration in the underground parts of licorice, glycyrrhizic acid content per plant, and growth rate compared to group M. Table 8. Total flavonoid concentration in licorice root and its growth rate compared to the CK and M groups. The results in Tables 2-8 show that treatment with nano-zinc oxide can increase the biomass and active ingredient content of licorice. Exogenous application of nano-zinc oxide can significantly increase the root length and dry matter accumulation of licorice, thereby increasing its biomass. Simultaneously, it effectively promotes the synthesis and accumulation of major active ingredients such as glycyrrhizic acid and glycyrrhizin. Furthermore, it can improve the physiological state of licorice under adverse conditions such as salt stress, thus increasing its biomass and active ingredient content, thereby achieving a synergistic improvement in licorice growth and quality.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. The application of nano zinc oxide in increasing the biomass and active ingredient content of licorice.

2. The application according to claim 1, characterized in that, The particle size of the nano zinc oxide is 1-50 nm.

3. The application according to claim 1 or 2, characterized in that, The nano zinc oxide is added to water or nutrient solution as a zinc source for irrigation and / or spraying of licorice during its growth period.

4. The application according to claim 3, characterized in that, The effective concentration of nano-zinc oxide in the water or nutrient solution is 5-60 mg / L; and / or; The watering is performed 3-6 times; the sprinkler irrigation is performed 2-6 times.

5. The application according to claim 3 or 4, characterized in that, Based on the land area of ​​licorice, the effective dosage of the nano-zinc oxide is (0.5-5) g / m². 2 .

6. The application according to claim 1 or 2, characterized in that, The improvement of licorice biomass includes: Increase the plant height and root length of licorice; Increase the dry weight of both the above-ground and underground parts of licorice; Increase the root-to-shoot ratio of licorice.

7. The application according to claim 1 or 2, characterized in that, The active ingredients include glycyrrhizin and / or glycyrrhizic acid.

8. The application according to claim 1 or 2, characterized in that, The total flavonoid concentration, based on the dry weight of the licorice root, is greater than or equal to 40 mg / g; and / or, Based on the dry weight of the underground part of the licorice, the concentration of glycyrrhizic acid is greater than or equal to 2.5 mg / g, and the concentration of glycyrrhizin is greater than or equal to 0.7 mg / g.

9. The application according to claim 1 or 2, characterized in that, The root-to-shoot ratio of the licorice is greater than or equal to 0.

55.

10. The application according to claim 1 or 2, characterized in that, The nano-zinc oxide is used to increase the biomass and active ingredient content of licorice under salt stress conditions; the salt stress conditions include: the sodium chloride concentration in the water or nutrient solution containing nano-zinc oxide is 130-180 mmol / L.

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