Method for promoting germination of angelica sinensis seeds

Abstract

The invention belongs to the technical field of plant cultivation, and particularly relates to a method for promoting germination of angelica sinensis seeds, which comprises the following steps: soaking the angelica sinensis seeds in warm water; placing the seeds soaked in the warm water in a potassium permanganate solution for disinfection; soaking the disinfected seeds in a plant hormone solution; and sowing the seeds soaked in the plant hormones on a sand bed, and breeding and emerging. According to the method, the germination conditions of the angelica sinensis seeds are screened, and germination is performed under specific seed soaking conditions, breeding temperature and illumination conditions, so that the germination efficiency of the angelica sinensis seeds is effectively improved; the method has important significance and value for the artificial propagation of the Angelica sinensis, and provides a theoretical basis for the comprehensive utilization of the Angelica sinensis.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant cultivation, and particularly relates to a method for promoting the germination of Angelica acutiloba seeds. Background Art

[0002] Angelica acutiloba is a perennial herbaceous plant, mostly growing in mountain forests, forest edges or thickets at an altitude of 2,500 - 3,000 meters. It adapts to a cool and humid climate, and has the characteristics of preferring shade, fearing strong light, and being cold-resistant. Angelica acutiloba is used as medicine with its root, and has the effects of enriching blood and promoting blood circulation, regulating menstruation and relieving pain, moistening the intestines and relaxing bowel movements, etc. In traditional medicine, it is often used to treat symptoms such as sallow complexion due to blood deficiency, dizziness and palpitation, irregular menstruation, amenorrhea and dysmenorrhea, deficiency-cold abdominal pain, and constipation due to intestinal dryness. Modern research also shows that Angelica acutiloba contains various chemical components, such as volatile oils, ferulic acid, etc., and these components have various pharmacological effects such as anti-thrombosis, improving blood circulation, and regulating immunity. Angelica acutiloba seeds have a natural dormancy phenomenon. This is due to the physiological mechanism inside the seeds. Maybe the embryo has not developed completely, or there are inhibitory substances inside the seeds. For example, the seed coat may limit the entry of water and oxygen, making the embryo unable to germinate normally. If this dormant state is not treated, it will greatly reduce the germination rate of the seeds and prolong the germination time. Its seed coat is relatively hard, and the seed germination has relatively strict requirements for temperature, humidity and light, which seriously restricts the reproduction of Angelica acutiloba.

[0003] Therefore, it is necessary to develop a safer and more reliable method that can promote the germination of Angelica acutiloba seeds. Summary of the Invention

[0004] In order to overcome the above technical defects, the present invention provides a method for promoting the germination of Angelica acutiloba seeds, optimizes various factors affecting the germination rate of Angelica acutiloba seeds, and under the optimized process conditions, compares the effects on seed germination under different water absorption conditions, different disinfection conditions, and different germination conditions.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for promoting the germination of Angelica acutiloba seeds, comprising the following steps:

[0007] S1. Take Angelica acutiloba seeds and soak them in warm water.

[0008] S2. Place the seeds soaked in warm water into a potassium permanganate solution for disinfection.

[0009] S3. Place the disinfected seeds into a plant hormone solution for soaking.

[0010] S4. Sow the seeds soaked in the plant hormone on a sand bed for breeding and seedling emergence.

[0011] Further, in the above S1, select well-developed and mature Angelica acutiloba seeds.

[0012] Further, in the step S1, the water temperature for seed soaking is 5 - 50 °C, or 10 - 45 °C, or 20 - 40 °C, or 25 - 40 °C, or 30 - 40 °C.

[0013] Further, in the step S1, the time for seed soaking is 24 - 36 h.

[0014] Further, in the step S2, the concentration of the potassium permanganate solution is 0.1% - 0.75% wt, or 0.15% - 0.75% wt, or 0.2% - 0.75% wt, or 0.25% - 0.5% wt, or 0.25% wt.

[0015] Further, in the step S2, the disinfection time is 5 - 30 min, or 10 - 30 min, or 15 - 25 min, or 15 - 20 min, or 15 min.

[0016] Further, in the step S3, the plant hormone is selected from one or more of GA3, IAA, and ABA; or selected from one of GA3 and IAA; or selected from IAA.

[0017] Further, in the step S3, the concentration of the plant hormone solution is 25 - 75 mg / L; for example, 25 - 60 mg / L, or 25 - 50 mg / L, or 40 - 75 mg / L, or 50 - 75 mg / L.

[0018] Further, in the step S4, the breeding temperature is 10 - 25 °C, or 10 - 20 °C, or 10 - 15 °C, or 15 - 25 °C, or 15 - 20 °C, or 20 °C.

[0019] Further, in the step S4, the illumination time is 1 - 24 h, or 5 - 20 h, or 10 - 20 h, or 10 - 15 h, or 12 h.

[0020] Compared with the prior art, by screening the germination conditions of Angelica acutiloba seeds, the present invention germinates under specific seed soaking conditions, breeding temperature, and illumination conditions, effectively improving the germination efficiency of Angelica acutiloba seeds; the present invention has important significance and value for the artificial propagation of Angelica acutiloba, providing a theoretical basis for the comprehensive utilization of Angelica acutiloba. Description of the Drawings

[0021] Figure 1 It is a diagram of Angelica acutiloba seeds and seedlings;

[0022] Figure 2 It is a water absorption rate curve diagram of Angelica acutiloba seeds;

[0023] Figure 3Effects of different disinfection methods on the germination of Angelica acutiloba seeds; a, b, c, d indicate P < 0.05 compared with the blank group;

[0024] Figure 4 Effects of different temperatures on the germination of Angelica acutiloba seeds; a, b, c, d indicate P < 0.05 compared with the blank group;

[0025] Figure 5 Effects of different light durations on the germination of Angelica acutiloba seeds; a, b, c, d indicate P < 0.05 compared with the blank group;

[0026] Figure 6 Effects of different germination beds on the germination of Angelica acutiloba seeds; a, b, c, d indicate P < 0.05 compared with the blank group. Specific Embodiments

[0027] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present invention fall within the scope of protection of the present invention.

[0028] Based on the present invention, the inventor selected well-developed and mature Angelica acutiloba seeds as samples (see Figure 1 A), schizocarp with wings, elliptical to ovate, 4 - 6 mm long, 3 - 4 mm wide; the surface is light yellow to brownish-brown, both ends are obtuse, and there is sometimes a small fruit stalk at the base. The mericarps are broadly elliptical, with 5 longitudinal ribs on the back, 3 dorsal ribs, linear, prominent, the lateral ribs extend into thin wings, the commissure is relatively flat, and there are oil tubes in the rib grooves and the commissure. Single-factor and orthogonal experiments were used to optimize the germination process to obtain Angelica acutiloba seedlings (see Figure 1 B), with white roots, slender taproots, 2 cotyledons at the top, thin papery, narrowly lanceolate, smooth edges, and the leaves are light yellow and gradually turn green. Specifically, the following steps are included:

[0029] S1. Take Angelica acutiloba seeds and soak them in warm water;

[0030] S2. Place the seeds soaked in warm water in a potassium permanganate solution for disinfection;

[0031] S3. Place the disinfected seeds in a plant hormone solution for soaking;

[0032] S4. Sow the seeds soaked in plant hormones on a sand bed for breeding and seedling emergence.

[0033] By comparing the differences in seed germination rates under different seed soaking conditions, different disinfection conditions, different concentrations of plant hormone solutions, and breeding temperatures and light conditions, more options are provided for the reproduction of Angelica acutiloba (Sieb.) Kitag.

[0034] Based on the present invention, in the step S1, well-developed and mature Angelica acutiloba (Sieb.) Kitag. seeds are selected.

[0035] Based on the present invention, in the step S1, the water temperature for seed soaking is 5 - 50 °C; in some specific embodiments, the water temperature for seed soaking can be selected as 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C;

[0036] Based on the present invention, in the step S1, the time for seed soaking is 24 - 36 h; in some specific embodiments, the time for seed soaking can be selected as 24 h, 26 h, 28 h, 30 h, 32 h, 34 h, 36 h;

[0037] Based on the present invention, in the step S2, the concentration of the potassium permanganate solution is 0.1% - 0.75% wt; in some specific embodiments, the concentration of the potassium permanganate solution can be selected as 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%;

[0038] Based on the present invention, in the step S2, the disinfection time is 5 - 30 min; in some specific embodiments, the disinfection time can be selected as 5 min, 10 min, 15 min, 20 min, 25 min, 30 min;

[0039] Based on the present invention, in the step S3, the plant hormone is selected from one or more of GA3, IAA, and ABA; in some specific embodiments, the plant hormone can be selected from one of GA3 and IAA; in some more preferred embodiments, the plant hormone is selected from IAA.

[0040] Based on the present invention, in the step S3, the concentration of the plant hormone solution is 25 - 75 mg / L; in some specific embodiments, the concentration of the plant hormone solution can be selected as 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, 45 mg / L, 50 mg / L, 55 mg / L, 60 mg / L, 65 mg / L, 70 mg / L, 75 mg / L;

[0041] Based on the present invention, in the step S4, the breeding temperature is 10 - 25 °C; in some specific embodiments, the breeding temperature can be selected as 10 °C, 15 °C, 20 °C, 25 °C;

[0042] Based on the present invention, in S4, the illumination time is 1 - 24 h; in some specific embodiments, the illumination time can be selected from 1 h, 3 h, 5 h, 7 h, 10 h, 13 h, 16 h, 19 h, 21 h, 24 h.

[0043] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0044] The sources of the reagents and instruments used in the following examples are as follows:

[0045] Test materials and reagents: RXZ - 300B intelligent artificial climate chamber (Ningbo Southeast Instrument Co., Ltd.), BT125D dual - range electronic analytical balance (Sartorius Company, Germany), disposable plastic petri dishes, gibberellin, 3 - indoleacetic acid, abscisic acid, potassium permanganate, qualitative filter paper, etc. were all purchased from Meibo Technology (Suzhou) Co., Ltd.

[0046] Data processing: Observation started from the day when the seeds were put into the incubator. When the hypocotyl breaking through the seed coat reached the length of the true seed itself, it was regarded as the germination standard. The number was counted regularly once a day, and the test was terminated after 15 days of cultivation. The germination potential and germination rate were calculated. Excel software was used for data processing, and the data results were subjected to Duncan multiple comparisons using SPSS20.0 statistical software. The test was repeated in parallel 3 times.

[0047] Example 1 Investigation of the optimal soaking time

[0048] Take 9 portions of Angelica acutiloba seeds, 30 seeds in each portion, place them in a petri dish lined with double - layer moist filter paper, and imbibe them under the condition of a constant temperature of 20 °C. Keep the filter paper continuously moist during the test time. Take out the seeds at 0, 1, 2, 4, 6, 8, 12, 24, 36, 48 h respectively, dry the surface moisture and then weigh them until the seed weight no longer changes, and draw a water absorption rate curve. The results are shown in Figure 2 .

[0049]

[0050] In the formula, m1 is the mass of the seed before water absorption (g), and m2 is the mass of the seed after water absorption (g)

[0051] As Figure 2 shown, during the whole imbibition process, the water absorption rate of Angelica acutiloba seeds increases with the extension of the soaking time ( Figure 3)。The seeds absorb water rapidly within 2 h, and the water absorption rate reaches 155.60% at 2 h. From 2 to 24 h, the water absorption is relatively slow, and the water absorption rate reaches 324.71% at 24 h. After 24 h, the water absorption is basically saturated. The imbibition process can be roughly divided into three stages: 0 - 2 h is the rapid water absorption stage, 2 - 24 h is the slow water absorption stage, and after 24 h is the water absorption saturation stage. It can be seen that the seeds of Angelica acutiloba have good water absorption, and the seed coat has good water permeability. Sufficient water should be provided in the first 24 h of the seed germination process.

[0052] Investigation of the optimal disinfection conditions in Example 2

[0053] Take a number of test seeds of Angelica acutiloba, and soak them in warm water at 50, 55, and 60 °C and in solutions of 0.1%, 0.25%, 0.5%, 0.75%, and 1% potassium permanganate (KMnO4) for 15 min respectively. Then, sow 50 seeds evenly in each petri dish lined with moist filter paper, and place them in an incubator at a temperature of 20 °C and with a 12 - h light cycle for a seed germination test. Calculate the germination rate and germination potential. The results are shown in Figure 3 .

[0054]

[0055] In the formula, M is the number of test seeds (pieces), M1 is the total number of germinated seeds at the end of the test (within 15 d) (pieces), and M2 is the total number of germinated seeds within the specified number of days (within 8 d) (pieces).

[0056] As Figure 3 shown, the effects of warm water soaking and KMnO4 soaking disinfection on the germination of Angelica acutiloba seeds are different. The germination rate of seeds soaked in warm water at 50 °C is 52.33%, lower than that of the blank group. The seeds soaked in warm water at 55 °C and 60 °C did not germinate, indicating that the seed coat of Angelica acutiloba is relatively thin, and warm water above 50 °C has damaged the vitality of Angelica acutiloba seeds. The germination rates of seeds soaked in KMnO4 solutions with different concentrations have all increased, indicating that surface disinfection of seeds with KMnO4 can reduce mildew occurrence and thus improve the seed germination rate. With the increase in the KMnO4 concentration, the germination rate shows a trend of first increasing and then decreasing. The germination rates of seeds soaked in 0.25% - 0.75% KMnO4 are 78.67%, 77.33%, and 78.67% respectively, with no significant difference. Except for the decrease in the germination potential of seeds soaked in 0.1% KMnO4, the other concentrations of soaking have little effect on the germination potential. The germination potential of seeds soaked in 0.25% KMnO4 is the highest, at 15.33%. Therefore, soaking seeds in 0.25% KMnO4 solution for 15 min is the appropriate disinfection method for the germination of Angelica acutiloba seeds.

[0057] Investigation of the optimal plant hormone solution in Example 3

[0058] The test seeds of Angelica acutiloba Kitag. were soaked in 0.25% potassium permanganate solution for 15 min, and then soaked in gibberellin (GA3), 3-indoleacetic acid (IAA), and abscisic acid (ABA) at concentrations of 0, 25, 50, 75, and 100 mg / L for 12 h respectively. After that, they were sown in petri dishes lined with moist filter paper and placed in an incubator at 20°C with a 12-h light cycle for the seed germination test. The germination rate, germination potential, and germination index were calculated. On the 12th day, 10 seedlings from each treatment were taken to measure the root length of the seedlings, and the vigor index was calculated. The results are shown in Tables 1-3.

[0059]

[0060] Vigor index (VI) = GI × S

[0061] Where Gt is the number of germinated seeds at day t (seeds), Dt is the number of days to germination at day t (days), and S is the average root length (mm).

[0062] Table 1 Effects of GA3 on the seed germination of Angelica acutiloba Kitag.

[0063]

[0064]

[0065] Note: a, b, c, d in the same column indicate significant differences (p < 0.05)

[0066] As can be seen from Table 1, the effects of soaking seeds with different concentrations of GA3 on the seed germination of Angelica acutiloba Kitag. are not the same. Soaking with 25-50 mg / L has no significant effect on the germination rate and germination index, but increases the germination potential, seedling root length, and vigor index; soaking with 75-100 mg / L reduces the germination rate and germination index; soaking with 100 mg / L also reduces the seedling root length and vigor index. The research shows that soaking seeds with 25-50 mg / L GA3 significantly improves the germination potential, seedling root length, and vigor index, and has a promoting effect on the seed germination of Angelica acutiloba Kitag.; soaking seeds with 75-100 mg / L GA3 significantly reduces the germination rate and germination index, and has an inhibitory effect on the seed germination of Angelica acutiloba Kitag.

[0067] Table 2 Effects of IAA on the seed germination of Angelica acutiloba Kitag.

[0068]

[0069] Note: a, b, c, d in the same column indicate significant differences (p < 0.05)

[0070] As can be seen from Table 2, the effects of soaking Yunnan Angelica sinensis seeds with different concentrations of IAA are different. Soaking with 25 mg / L reduces the vigor index and has no obvious effect on other indexes. Soaking with 50 - 75 mg / L increases the germination rate and germination potential, and soaking with 50 mg / L also increases the root length and vigor index of seedlings; soaking with 100 mg / L significantly reduces the germination rate, germination potential, root length of seedlings, germination index and vigor index. The results show that soaking with 50 - 75 mg / L IAA significantly increases the germination rate and germination potential, which has a promoting effect on the germination of Yunnan Angelica sinensis seeds. Soaking with 100 mg / L IAA significantly reduces all the measured indexes, which has a complete inhibitory effect on the germination of Yunnan Angelica sinensis seeds.

[0071] Table 3 Effects of ABA on the germination of Yunnan Angelica sinensis seeds

[0072]

[0073]

[0074] Note: a, b, c, d in the same column indicate significant differences (p < 0.05)

[0075] As can be seen from Table 3, the effects of soaking Yunnan Angelica sinensis seeds with different concentrations of ABA are different. Soaking with 25 - 50 mg / L reduces the root length and vigor index of seedlings, and soaking with 25 mg / L also reduces the germination rate, germination potential and germination index; soaking with 75 mg / L has no obvious effect on all the measured indexes; soaking with 100 mg / L reduces the germination potential, vigor index and germination index. The results show that soaking with 25 mg / L ABA significantly reduces all the measured indexes, which has an obvious inhibitory effect on the germination of Yunnan Angelica sinensis seeds. Soaking with 50 mg / L and 100 mg / L ABA has an inhibitory effect on the germination of Yunnan Angelica sinensis seeds.

[0076] It shows that soaking with appropriate concentrations of GA3 and IAA can affect the germination potential, improve the emergence rate and emergence uniformity, can affect the root length of seedlings, improve their ability to adapt to the environment, thereby improving the transplanting survival rate, and further enhancing the overall growth quality and yield of Yunnan Angelica sinensis.

[0077] Example 4 Investigating the effects of different temperatures on seed germination

[0078] After soaking the tested seeds of Yunnan Angelica sinensis with 0.25% potassium permanganate solution for 15 min, they were sown in petri dishes lined with moist filter paper and placed in an incubator at temperatures of 10, 15, 20, 25, 30 °C and with a 12 h light for a seed germination test. The results are shown in Figure 4 .

[0079] As Figure 4As shown in the figure, temperature has a significant impact on the germination of Angelica acutiloba seeds. With the increase of temperature, the germination rate first increases and then decreases. Both low temperature (10°C) and high temperature (30°C) inhibit seed germination. The germination rate increases significantly at 15 - 25°C, especially at 15 - 20°C, where the germination rate is significantly higher than that at 25°C, being 77.33% - 78.67%. Within a certain temperature range (10 - 25°C), the germination potential increases with the increase of temperature, and the germination potential is the highest at 20 - 25°C, being 15.33% - 15.67%. Therefore, 20°C is the suitable temperature for the germination of Angelica acutiloba seeds.

[0080] Example 5 examines the effect of different light exposure times on seed germination

[0081] After the tested Angelica acutiloba seeds were soaked in 0.25% potassium permanganate solution for 15 min, they were sown in petri dishes lined with moist filter paper and placed in an incubator at a temperature of 20°C for a seed germination test with light exposure times of 0, 12, and 24 h respectively. The results are shown in Figure 5 .

[0082] As Figure 5 shown, light has no obvious effect on the germination of Angelica acutiloba seeds, and there are no significant differences in the germination rate and germination potential under different light exposure times. Therefore, Angelica acutiloba seeds are not sensitive to light. A certain period of light exposure is more beneficial to seedling growth. Therefore, 12 h of light exposure is the suitable light exposure time for the germination of Angelica acutiloba seeds.

[0083] Example 5 examines the effect of different germination beds on seed germination

[0084] After the tested Angelica acutiloba seeds were soaked in 0.25% potassium permanganate solution for 15 min, they were sown in petri dishes with 5 different germination beds (on paper, between papers, on wrinkled paper, on sand, between sands) respectively and placed in an incubator at a temperature of 20°C with a light exposure of 12 h for a seed germination test. The results are shown in Figure 6 .

[0085] As Figure 6 shown, the germination bed has a significant impact on the germination of Angelica acutiloba seeds. The highest germination rate on sand is 80.67%, which has no statistical difference from the germination rates on paper, between papers, and on wrinkled paper, and is significantly higher than that between sands. The highest germination potential on sand is 27.33%, which is significantly higher than that of other germination beds. The moisture retention effects on paper, on wrinkled paper, and on sand are comparable, all being beneficial to seed germination. Between papers will cover the seeds with a relatively large gap, and the germination rate is not affected, but it will significantly reduce the germination potential and affect the uniformity of seedling emergence. The covering degree between sands is higher and the air permeability is poor, resulting in the inhibition of seed germination, with the lowest germination rate and germination potential. Therefore, sand is the suitable germination bed for the germination of Angelica acutiloba seeds.

[0086] Comparative Example 1

[0087] The test seeds of Angelica acutiloba Kitag. were soaked in 0.25% potassium permanganate solution for 15 min, and then soaked in naphthalene acetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D) and cytokinin (6-BA) at concentrations of 0, 25, 50, 75, and 100 mg / L for 12 h, respectively. After that, they were sown in petri dishes lined with moist filter paper and placed in an incubator at 20 °C with a 12-h light period for a seed germination test. The germination rate, germination potential, and germination index were calculated. On the 12th day, 10 seedlings from each treatment were taken to measure the root length of the seedlings, and the vigor index was calculated. The results are shown in Tables 4 - 6.

[0088] Table 4 Effects of NAA on the Seed Germination of Angelica acutiloba Kitag.

[0089]

[0090] Note: a, b, c, d in the same column indicate significant differences (p < 0.05).

[0091] Table 5 Effects of 2,4-D on the Seed Germination of Angelica acutiloba Kitag.

[0092]

[0093] Note: a, b, c, d in the same column indicate significant differences (p < 0.05).

[0094] Table 6 Effects of 6-BA on the Seed Germination of Angelica acutiloba Kitag.

[0095]

[0096] Note: a, b, c, d in the same column indicate significant differences (p < 0.05).

[0097] As can be seen from Tables 4 - 6, naphthalene acetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D) and cytokinin (6-BA) all significantly reduced the germination rate and germination potential (p < 0.01), and had a strong inhibitory effect on the seed germination of Angelica acutiloba Kitag. At the same time, it was also found that the roots of the seedlings soaked in some hormones were significantly shorter and the color was reddish, which might be due to the excessive use of hormones inhibiting root growth.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for promoting germination of Angelica sinensis seeds, characterized in that: The following steps are involved: S1. Soak the seeds of Danggui in warm water; S2. Place the seeds soaked in warm water in a potassium permanganate solution for disinfection; S3. Soaking the sterilized seeds in a plant hormone solution; S4. Sow the seeds soaked with plant hormones on a sand bed and breed them to seedlings.

2. The method according to claim 1, characterized in that In S1, well-developed and mature Angelica sinensis seeds are selected.

3. The method according to claim 1 or 2, characterized in that: In S1, the soaking water temperature is 5-50°C, or 10-45°C, or 20-40°C, or 25-40°C, or 30-40°C.

4. The method according to claim 3, characterized in that In S1, the soaking time is 24 to 36 hours.

5. The method according to claim 1, characterized in that In S2, the concentration of the potassium permanganate solution is 0.1% to 0.75% wt, or 0.15% to 0.75% wt, or 0.2% to 0.75% wt, or 0.25% to 0.5% wt, or 0.25% wt.

6. The method according to any one of claims 1, 3 or 5, characterized in that: In S2, the disinfection time is 5-30 min, or 10-30 min, or 15-25 min, or 15-20 min, or 15 min.

7. The method according to claim 1, characterized in that In S3, the plant hormone is selected from one or more of GA3, IAA, and ABA; or selected from one of GA3 and IAA; or selected from IAA.

8. The method according to any one of claims 1, 3, 5 or 7, characterized in that: In S3, the concentration of the plant hormone solution is 25-75 mg / L; for example, 25-60 mg / L, or 25-50 mg / L, or 40-75 mg / L, or 50-75 mg / L.

9. The method according to claim 1, characterized in that: In S4, the breeding temperature is 10-25°C, or 10-20°C, or 10-15°C, or 15-25°C, or 15-20°C, or 20°C.

10. The method according to any one of claims 1, 3, 5, 7 or 9, characterized in that: In S4, the illumination time is 1-24h, or 5-20h, or 10-20h, or 10-15h, or 12h.

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