Preparation method of detoxified sweet potato seedlings

Abstract

The invention provides a preparation method of detoxified sweet potato seedlings, which comprises the following cultivation steps: cleaning sweet potatoes, putting the sweet potatoes in a degerming solution for accelerating germination, disinfecting new stem tips, and putting the stem tips in a culture medium I for culture to obtain sweet potato stem tips; when 4-5 leaves grow on the stem tips of the sweet potatoes, stem tip meristem tissue is inoculated into a culture medium II and cultured into 8-9 stem segments, and sweet potato seedlings are obtained; sweet potato seedlings are transplanted to a seedling raising plate containing a nutrient medium and cultured for 30-35 days in an artificial climate chamber, and the seedlings are transplanted to soil for breeding. According to the preparation method of the detoxified sweet potato seedlings, the growth condition of the sweet potato seedlings is remarkably improved, the plant height, the root system number and the root system length of the sweet potato seedlings are increased, the net photosynthetic rate (Pn) and the stomatal conductance (Gs) of the detoxified sweet potato seedlings are remarkably improved, and healthy growth of sweet potatoes in the seedling stage is facilitated.

Description

Technical Field

[0001] The invention relates to the field of planting, and in particular to a method for preparing virus-free sweet potato seedlings. Background Art

[0002] Sweet potato, a plant of the genus yam in the leguminous family, is also called sweet potato. The description of sweet potato in "Compendium of Materia Medica" compiled by Li Shizhen, a Chinese medicine scientist in the Ming Dynasty, quoted the original text of "Records of Strange Things" by Yang Fu in the Eastern Han Dynasty: "Sweet potato comes from the south of Jiaoguang. People plant it in February and harvest it in October. Its root is similar to taro, and there are also huge ones. The big ones are like goose eggs, and the small ones are like chicken and duck eggs. Peel off the purple skin, and the flesh is white like fat. Southerners use it as rice, and the fruit is delicious whether steamed or roasted. It is very sweet at first, but becomes less sweet as time goes by." At the same time, the Compendium of Materia Medica also quoted the original text of "Description of Southern Plants" by Ji Han of the Jin Dynasty: "Sweet potatoes are similar to yam or taro. The roots and leaves are also like taro. The roots are as big as fists, and the taste of steamed food is the same as yam, but not very cold. The non-farmers in Zhuya only grow this, steam, cut, and dry it to make food, which is called potato grain. The people in the sea live longer, and they do not eat grains, but eat sweet potatoes." The text states that sweet potatoes are cultivated as a kind of food, which is an important economic crop and is deeply loved by consumers. At present, the cultivation of sweet potato seedlings has the following important problems: sweet potatoes are asexually propagated crops, mainly propagated by stems and tubers. During the cultivation process, the stems and leaves are easily bitten by aphids, planthoppers and other virus-transmitting pests and infected with viruses. Once infected, the virus enters the tubers through the nutrient conduction system. After years of continuous planting, the amount and types of viruses carried by the tubers gradually increase, seriously affecting the yield and quality of sweet potatoes. There are more than 30 sweet potato viruses reported worldwide, and the ones that have a greater impact on sweet potato production include sweet potato geminivirus and sweet potato chlorotic stunt virus. The main symptoms of virus diseases on the aboveground part of sweet potatoes include leaf spots, mosaics, curled leaves, leaf shrinkage and leaf yellowing, with leaf spots being the main type, such as purple feather spots, purple spots, and yellow spots. The symptoms on the tubers are mainly black-brown or yellow-brown cracks. In view of the fact that no sweet potato varieties with high resistance to virus diseases have been bred in China so far, and there are no efficient pesticides for the prevention and control of sweet potato virus diseases, the promotion and application of virus-free sweet potato seedlings is currently an effective method for preventing and controlling sweet potato virus diseases and improving sweet potato yield and quality. The traditional production of virus-free sweet potato seedlings is divided into three to four stages. In the first year, seed potatoes are planted in laboratory net sheds; in the second year, they are planted in the field and good seed potatoes are harvested; in the third and fourth years, the good seed potatoes are raised as commercial seedlings for sweet potato production. This method lasts for a long time and is very easy to be infected with viruses during the seedling raising process, resulting in a decline in the quality of sweet potatoes, a decrease in yield, and a degeneration of the species. Summary of the invention

[0003] In view of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing virus-free sweet potato seedlings to solve the above-mentioned problem.

[0004] The technical solution of the present invention:

[0005] A method for preparing virus-free sweet potato seedlings comprises the following steps:

[0006] S1: Wash the sweet potato, place it in a sterilizing solution to germinate, disinfect the newly grown shoot tip, place it in culture medium I and culture it for 5-10 days to obtain the sweet potato shoot tip;

[0007] S2: When 5 to 7 leaves grow on the tip of the sweet potato stem, the tip meristem is inoculated into medium II and cultured until 8 to 9 stem segments are reached to obtain sweet potato seedlings;

[0008] S3: Transplant the sweet potato seedlings onto a seedling tray containing a nutrient matrix, cultivate them in an artificial climate chamber for 30-35 days, and then transplant the seedlings into sterilized soil for breeding.

[0009] Further, S1, the total mass proportion of thiophanate-methyl and λ-cyhalothrin in the sterilization solution is 0.02%-0.04%, and the sterilization solution is composed of thiophanate-methyl and λ-cyhalothrin in a mass ratio of 1:0.1-0.2.

[0010] Further, S1, the germination is carried out by placing the sweet potato in a mixed matrix sterilized at high temperature for germination, the mixed matrix comprising coconut bran, perlite, terminalia chebula powder and acarbose in a mass ratio of 1-1.2:1-1.5:0.4-0.5:0.1-0.3, the germination temperature is 30-36°C, the holding time is 14-16h, and then the temperature is reduced to 25-27°C and the holding time is 6-10d.

[0011] Furthermore, the particle size of the terminalia chebula powder is 30-40 microns.

[0012] Further, S1, the stem tip is disinfected by rinsing the stem tip with water for 2-4 times, soaking it in 75% alcohol by mass fraction for 10-12s, soaking it in 1-1.5% sodium hypochlorite solution by mass fraction for sterilization, the sterilization time is 10-15min, and rinsing it with water for 3-5 times.

[0013] Further, S1, the culture medium I includes the following raw materials in parts by mass: 5-7 g / L NH4H2PO3, 1-2 g / L KH2PO4, 3-4 g / L MgSO4·7H2O, 2-3 g / L Ca(NO3)2·4H2O, 2-2.5 g / L FeSO4·7H2O, 0.2-0.4 g / L IAA, 0.1-0.3 g / L cysteine, 1-1.5 g / L brassinolide and 0.1-0.2 g / L 6-furfurylaminopurine.

[0014] Further, S1, the culture medium culture conditions are: mix the culture medium raw materials, dilute 8-10 times with distilled water, add 3-4 g / L agar, adjust the pH value to 5.6-6.0, sterilize with high pressure steam, the sterilization temperature is 100℃-135℃, the time is 40min-50min, and solidify at room temperature.

[0015] Further, S2, the culture medium II includes the following raw materials in parts by mass: KNO3 7-9 g / L, KH2PO4 2-4 g / L, NAA 0.5-0.6 g / L, 6-BA 0.4-0.5 g / L, IAA 0.2-0.3 g / L and GA3 0.1-0.3 g / L.

[0016] Furthermore, the culture temperature in the artificial climate chamber is 26-30°C, the light intensity is 1000-1200 lux, and the light cycle is 8-8.5h / d.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The preparation method of the virus-free sweet potato seedlings of the present invention significantly improves the growth of the sweet potato seedlings, and increases the plant height, root number and root length of the sweet potato seedlings. The photosynthetic characteristic test shows that the net photosynthetic rate (Pn) and stomatal conductance (Gs) of the virus-free sweet potato seedlings prepared by the method of the present invention are significantly improved. The improvement of these two indicators indicates that the ability of the sweet potato seedlings to synthesize organic matter using light energy and the net photosynthetic rate are improved, and the ability of the plant to produce carbohydrates while increasing the carbon dioxide absorbed in photosynthesis is increased, thereby improving the photosynthesis efficiency and the growth rate of the seedlings. DETAILED DESCRIPTION

[0019] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention. The experimental methods used in the examples of the present invention are all conventional methods unless otherwise specified.

[0020] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0021] The raw material used in this embodiment, hiophanate-methyl: the molecular formula is C 12 H 14 N4O4S2, relative molecular weight is 342.39, CAS number is 23564-05-8, purchased from Shanghai Ruichu Biotechnology Co., Ltd.; λ-cyhalothrin: molecular formula is C 23 H 19 C lF3NO3, relative molecular mass is 449.85, purity is 95%, purchased from Mengcheng Technology (Shanghai) Co., Ltd.; IAA: full name indoleacetic acid, chemical formula is C 10 H9NO2, relative molecular weight is 175.184, purchased from Hubei Bolan Chemical Co., Ltd.; NAA (1-Naphthaleneacetic acid): full name 1-naphthaleneacetic acid, molecular formula is C 12 H 10 O2, relative molecular weight is 175.184, purchased from Hubei Bolan Chemical Co., Ltd.; 6-BA: full name 6-benzylaminoadenine, molecular formula is C 12 H 11 N5, with a relative molecular weight of 225.26, was purchased from Shanghai Guchen Biotechnology Co., Ltd.; GA3 (Gibberellin A3): full name gibberellin, chemical formula is C 19 H 22 O6, with a relative molecular weight of 346.37, was purchased from Jiangxi Xinruifeng Biochemical Co., Ltd.

[0022] Example 1

[0023] The preparation of a virus-free sweet potato seedling comprises the following steps:

[0024] Step (1): Wash the sweet potato with clean water and place it in a sterilizing solution for germination. After the sweet potato is sterilized and germinated in the sterilizing solution, the new stem tip is disinfected. First, the stem tip is rinsed with water for 2-4 times, then soaked in 75% alcohol for 10 seconds, and then soaked in 1% sodium hypochlorite solution for sterilization for 10 minutes, and rinsed with water 3 times. After the stem tip is sterilized, it is placed in a high-temperature sterilized mixed matrix for germination. The mixed matrix includes coconut bran, perlite, terminalia chebula powder and acarbose in a mass ratio of 1:1:0.4:0.1, wherein the terminalia chebula powder has a particle size of 30 microns, the germination temperature is 30°C, the holding time is 14 hours, the temperature is lowered to 25°C, the holding time is 6 days, and then placed in culture medium I for cultivation.

[0025] The sterilization solution is composed of thiophanate-methyl and λ-cyhalothrin in a mass ratio of 1:0.1, and the total mass proportion of thiophanate-methyl and λ-cyhalothrin in the sterilization solution is 0.02%.

[0026] Culture medium I includes the following raw materials in parts by mass: 5 g / L NH4H2PO3, 1 g / L KH2PO4, 3 g / L MgSO4·7H2O, 2 g / L Ca(NO3)2·4H2O, 2 g / L FeSO4·7H2O, 0.2 g / L IAA, 0.1 g / L cysteine, 1 g / L brassinolide and 0.1 g / L 6-furfurylaminopurine.

[0027] Culture medium conditions: Mix the culture medium raw materials, dilute 8 times with distilled water, add 3 g / L agar, adjust the pH value to 5.6, sterilize with high pressure steam at 100°C for 40 min, and solidify at room temperature.

[0028] Step (2): When five leaves grow from the tip of the sweet potato stem, the tip meristem is inoculated into culture medium II and cultured until eight stem segments are obtained to obtain sweet potato seedlings; wherein, culture medium II comprises the following raw materials in parts by weight: 7 g / L KNO3, 2 g / L KH2PO4, 0.5 g / L NAA, 0.4 g / L 6-BA, 0.2 g / L IAA and 0.1 g / L GA3.

[0029] Step (3): Transplant the sweet potato seedlings onto a seedling tray containing a nutrient matrix, and culture them in an artificial climate chamber for 30 days. The temperature in the artificial climate chamber is 26° C., the light intensity is 1000 lux, and the light cycle is 8 h / d. Transplant the seedlings into sterilized soil for breeding.

[0030] Example 2

[0031] The preparation of a virus-free sweet potato seedling comprises the following steps:

[0032] Step (1): Wash the sweet potato with clean water and place it in a sterilizing solution for germination. After the sweet potato is sterilized and germinated in the sterilizing solution, the newly formed stem tip is disinfected. First, the stem tip is rinsed with water 4 times, then soaked in 75% alcohol by mass for 12 seconds, then soaked and sterilized in 1.5% sodium hypochlorite solution by mass for 15 minutes, and rinsed with water 5 times. After the stem tip is sterilized, it is placed in a high-temperature sterilized mixed matrix for germination, the mixed matrix includes coconut bran, perlite, chebula powder and acarbose in a mass ratio of 1.2:1.5:0.5:0.3, wherein the chebula powder has a particle size of 40 microns, the germination temperature is 36°C, the holding time is 16 hours, then cooled to 27°C, the holding time is 10 days, and then placed in culture medium I for culture.

[0033] The sterilization solution is composed of thiophanate-methyl and λ-cyhalothrin in a mass ratio of 1:0.2, and the total mass proportion of thiophanate-methyl and λ-cyhalothrin in the sterilization solution is 0.04%.

[0034] Culture medium I includes the following raw materials in parts by mass: 7 g / L NH4H2PO3, 2 g / L KH2PO4, 4 g / L MgSO4·7H2O, 3 g / L Ca(NO3)2·4H2O, 2.5 g / L FeSO4·7H2O, 0.4 g / L IAA, 0.3 g / L cysteine, 1.5 g / L brassinolide and 0.2 g / L 6-furfurylaminopurine.

[0035] Culture medium conditions: Mix the culture medium raw materials, dilute 10 times with distilled water, add 4 g / L agar, adjust the pH value to 6.0, sterilize with high pressure steam at a sterilization temperature of 135°C for 50 min, and solidify at room temperature.

[0036] Step (2): When seven leaves grow from the tip of the sweet potato stem, the tip meristem is inoculated into culture medium II and cultured until nine stem segments are obtained to obtain sweet potato seedlings; wherein, culture medium II comprises the following raw materials in parts by weight: 9 g / L KNO3, 4 g / L KH2PO4, 0.6 g / L NAA, 0.5 g / L 6-BA, 0.3 g / L IAA and 0.3 g / L GA3.

[0037] Step (3): Transplant the sweet potato seedlings onto a seedling tray containing a nutrient matrix, and culture them in an artificial climate chamber for 35 days. The temperature of the artificial climate chamber is 30° C., the light intensity is 1200 lux, and the light cycle is 8.5 h / d. Transplant the seedlings into sterilized soil for breeding.

[0038] Example 3

[0039] The preparation of a virus-free sweet potato seedling comprises the following steps:

[0040] Step (1): Wash the sweet potato with clean water and place it in a sterilizing solution for germination. After the sweet potato is sterilized and germinated in the sterilizing solution, the new stem tip is disinfected. First, the stem tip is rinsed with water 3 times, then soaked in 75% alcohol for 11 seconds, then soaked in 1.2% sodium hypochlorite solution for sterilization for 12 minutes, and rinsed with water 4 times. After the stem tip is sterilized, it is placed in a high-temperature sterilized mixed matrix for germination. The mixed matrix includes coconut bran, perlite, terminalia chebula powder and acarbose in a mass ratio of 1.1:1.3:0.4:0.2, wherein the terminalia chebula powder has a particle size of 35 microns, the germination temperature is 34°C, the holding time is 15 hours, the temperature is lowered to 26°C, the holding time is 8 days, and then placed in culture medium I for cultivation.

[0041] The sterilization solution is composed of thiophanate-methyl and λ-cyhalothrin in a mass ratio of 1:0.1, and the total mass proportion of thiophanate-methyl and λ-cyhalothrin in the sterilization solution is 0.03%.

[0042] Culture medium I includes the following raw materials in parts by mass: 6 g / L NH4H2PO3, 1.5 g / L KH2PO4, 3.5 g / L MgSO4·7H2O, 2.5 g / L Ca(NO3)2·4H2O, 2.2 g / L FeSO4·7H2O, 0.3 g / L IAA, 0.2 g / L cysteine, 1.2 g / L brassinolide and 0.2 g / L 6-furfurylaminopurine.

[0043] Culture medium conditions: Mix the culture medium raw materials, dilute 9 times with distilled water, add 3.5 g / L agar, adjust the pH value to 5.8, sterilize with high pressure steam at 120°C for 45 min, and solidify at room temperature.

[0044] Step (2): When six leaves grow from the tip of the sweet potato stem, the tip meristem is inoculated into culture medium II and cultured until eight stem segments are obtained to obtain sweet potato seedlings; wherein, culture medium II comprises the following raw materials in parts by weight: 8 g / L KNO3, 3 g / L KH2PO4, 0.5 g / L NAA, 0.4 g / L 6-BA, 0.2 g / L IAA and 0.2 g / L GA3.

[0045] Step (3): Transplant the sweet potato seedlings onto a seedling tray containing a nutrient matrix, and culture them in an artificial climate chamber for 33 days. The temperature of the artificial climate chamber is 28° C., the light intensity is 1100 lux, and the light cycle is 8 h / d. Transplant the seedlings into sterilized soil for breeding.

[0046] Comparative Example 1

[0047] The difference between Comparative Example 1 and Example 3 is that the germination step in the sterilization solution is removed in step 1, and the other methods and steps are the same as those in Example 3.

[0048] Comparative Example 2

[0049] The difference between Comparative Example 2 and Example 3 is that the components of the mixed matrix in step 1 are removed from terminalia chebula powder and acarbose, and the other methods and steps are the same as those in Example 3.

[0050] Comparative Example 3

[0051] The difference between Comparative Example 3 and Example 3 is that the composition of Culture Medium I is modified to be the same as that of Culture Medium II, the sterilizing solution is modified to an alcohol solution with a mass fraction of 75%, and the other methods and steps are the same as those of Example 3.

[0052] test

[0053] Experiment 1: Rooting culture experiment. Healthy sweet potatoes were selected, and sweet potatoes with thick and strong root tubers were selected. The sweet potato variety was a commercially available variety (Yanshu 25). The methods of Examples 1-3 and Comparative Examples 1-3 were used for rooting culture. Five equilibrium tests were performed for each culture. After 21 days of culture, the average rooting parameters were statistically analyzed at a unified time (see Table 1), and the number of roots was determined by the ruler method.

[0054] Table 1

[0055]

[0056]

[0057] Note: a and b indicate significant differences at P < 0.05.

[0058] Experiment 2: Photosynthetic characteristics test. Leaves at the 3rd and 4th leaf order were selected as the test objects. The Yanxin-1102 portable photosynthesis system was used to measure photosynthetic parameters including net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and intercellular CO2 concentration (C i ), using an open air path, and setting the photosynthetically active radiation to 1200 μmoL -2 ·s -1 Five equilibrium tests were performed for each culture. After 20-21 days of culture, the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and intercellular CO2 concentration (C i ), see Table 2 for specific data.

[0059] Table 2

[0060]

[0061] Note: a and b indicate significant differences at P < 0.05.

[0062] The rooting culture test showed that the plant height, the number of roots, the length of roots and the growth of the virus-free sweet potato seedlings cultured in Examples 1 to 3 were better than those in Comparative Examples 1 to 3. After removing the germination step in the sterilizing solution, the plant height, the number of roots, the length of roots and the growth of the sweet potato seedlings were significantly reduced. At the same time, changing the composition of the mixed matrix and the composition of the sterilizing solution significantly affected the growth of the sweet potato seedlings.

[0063] The photosynthetic characteristic test shows that the net photosynthetic rate (Pn) and stomatal conductance (Gs) of the virus-free sweet potato seedlings cultured in Examples 1 to 3 are significantly improved. The net photosynthetic rate (Pn) directly reflects the ability of the sweet potato seedlings to synthesize organic matter using light energy. The higher the net photosynthetic rate, the more carbon dioxide the plant absorbs during photosynthesis, and the more carbohydrates it produces, thereby increasing the biomass. This shows that the ability of the virus-free sweet potato seedlings cultured in Examples 1 to 3 to synthesize organic matter is significantly increased while increasing the biomass. The significant improvement in stomatal conductance (Gs) shows that the sweet potato seedlings have enhanced their absorption of CO2 and water utilization efficiency, thereby improving photosynthesis efficiency and seedling growth rate. Comparative Examples 1-3 removed the germination step in the sterilization solution, changed the composition of the mixed matrix and the composition of the sterilization solution, and significantly reduced the net photosynthetic rate (Pn) and stomatal conductance (Gs) of the sweet potato seedlings, affecting the photosynthetic efficiency of the seedlings. Therefore, the preparation method of the virus-free sweet potato seedlings of Examples 1-3 is beneficial to the growth of the seedlings, and can effectively improve the photosynthetic efficiency of the seedlings, and increase their plant height and root number.

[0064] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing virus-free sweet potato seedlings, characterized in that: The cultivation steps include: S1: Wash the sweet potato, place it in a sterilizing solution to germinate, disinfect the newly grown shoot tip, place it in culture medium I and culture it for 5-10 days to obtain the sweet potato shoot tip; S2: When 4-5 leaves grow on the tip of the sweet potato stem, the tip meristem is inoculated into medium II and cultured until 8-9 stem segments are obtained to obtain sweet potato seedlings; S3: Transplant the sweet potato seedlings onto a seedling tray containing a nutrient matrix, cultivate them in an artificial climate chamber for 30-35 days, and then transplant the seedlings into the soil for breeding.

2. The method for preparing the virus-free sweet potato seedlings according to claim 1, characterized in that: Step S1, the sterilization solution is composed of thiophanate methyl and λ-cyhalothrin in a mass ratio of 1:0.1-0.2, and the total mass proportion of thiophanate methyl and λ-cyhalothrin in the sterilization solution is 0.02%-0.04%.

3. The method for preparing the virus-free sweet potato seedlings according to claim 1, characterized in that: Step S1, the germination, placing the sweet potato in a high-temperature sterilized mixed matrix for germination, the mixed matrix comprising coconut bran, perlite, terminalia chebula powder and acarbose in a mass ratio of 1-1.2:1-1.5:0.4-0.5:0.1-0.

3.

4. The method for preparing virus-free sweet potato seedlings according to claim 1, characterized in that: Step S1, the germination temperature is 30-36°C, maintained for 14-16 hours, then cooled to 25-27°C, maintained for 6-10 days.

5. The method for preparing virus-free sweet potato seedlings according to claim 4, characterized in that: The particle size of the terminalia chebula powder is 30-40 microns.

6. The method for preparing virus-free sweet potato seedlings according to claim 1, characterized in that: Step S1, the stem tip is disinfected by washing the stem tip with water for 2-4 times, then soaking and sterilizing it in a sodium hypochlorite solution with a mass fraction of 1-1.5% for 10-15 minutes, and then washing it with water for 3-5 times after sterilization.

7. The method for preparing virus-free sweet potato seedlings according to claim 1, characterized in that: Step S1, the culture medium I includes the following raw materials in parts by weight: 5-7 g / L NH4H2PO3, 1-2 g / L KH2PO4, 3-4 g / L MgSO4·7H2O, 2-3 g / L Ca(NO3)2·4H2O, 2-2.5 g / L FeSO4·7H2O, 0.2-0.4 g / L IAA, 0.1-0.3 g / L cysteine, 1-1.5 g / L brassinolide and 0.1-0.2 g / L 6-furfurylaminopurine.

8. The method for preparing virus-free sweet potato seedlings according to claim 1, characterized in that: Step S1, the culture medium culture conditions: mix the culture medium raw materials, dilute 8-10 times with distilled water, add 3-4 g / L agar, adjust the pH value to 5.6-6.0, sterilize with high pressure steam at a sterilization temperature of 100°C-135°C for 40min-50min, and solidify at room temperature.

9. The method for preparing virus-free sweet potato seedlings according to claim 1, characterized in that: Step S2, the culture medium II includes the following raw materials in parts by mass: KNO3 is 7-9 g / L, KH2PO4 is 2-4 g / L, NAA is 0.5-0.6 g / L, 6-BA is 0.4-0.5 g / L, IAA is 0.2-0.3 g / L and GA3 is 0.1-0.3 g / L.

10. The method for preparing virus-free sweet potato seedlings according to claim 1, characterized in that: Step S3, the temperature of the artificial climate chamber is 26-30°C, the light intensity is 1000-1200 lux, and the light cycle is 8-8.5h / d.

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