A method for improving the survival rate of rice radiation-induced mutation seedlings and / or promoting the growth of rice radiation-induced mutation seedlings

Abstract

The present invention provides a method for improving the survival rate of rice radiation-induced mutagenesis seedlings and / or promoting the growth of rice radiation-induced mutagenesis seedlings, and belongs to the field of agricultural technology. The present invention provides the use of brassinolide in improving the survival rate of rice radiation-induced mutagenesis seedlings and / or promoting the growth of rice radiation-induced mutagenesis seedlings. Radiation treatment of rice seeds to create mutants is one of the important ways to innovate germplasm resources. However, irradiating rice seeds will affect their physiological metabolic activities, resulting in abnormal growth or even death of seedlings, thereby significantly reducing the mutagenesis efficiency. The present invention utilizes the plant growth regulator brassinolide to treat rice seeds at different growth stages after radiation treatment, which can improve the survival rate of induced seedlings, reduce the loss of mutant genes, and thus improve the efficiency of radiation mutagenesis.

Description

Technical Field

[0001] The invention belongs to the technical field of agriculture, and in particular relates to a method for improving the survival rate of radiation-induced rice seedlings and / or promoting the growth of radiation-induced rice seedlings. Background Art

[0002] Rice is China's most important food crop and a key staple in Southeast Asia. Rice production in Africa has also seen rapid growth in recent years. The most important reason for the remarkable success of rice production is the development of new varieties supported by innovative germplasm resources. With economic development, rice breeding aims not only for high yield, high quality, disease resistance, and insect resistance, but also to meet consumer demand for specialized rice varieties, improve nitrogen fertilizer efficiency to protect the environment, and address the need for improved rice varieties resistant to high temperatures and droughts due to extreme climate change. Therefore, there is a need to continuously develop high-quality germplasm resources with characteristics such as disease and / or insect resistance, tolerance to high temperatures, drought, salinity, nutrient deficiency, high nitrogen utilization efficiency, excellent taste, giant embryos, and functional rice. Radiation treatment of seeds to create mutants is one of the key approaches to rice germplasm innovation.

[0003] Creating mutants through nuclear radiation is an important avenue for germplasm innovation. Gamma-ray irradiation of rice seeds can cause fragmentation, displacement, deletion, or recombination of chromosomal DNA fragments, resulting in genetic mutations. This can also affect rice's physiological metabolic activities, such as photosynthesis, respiration, water transport, nutrient absorption, and hormone regulation. It can also damage cell membranes and organelles, affecting osmotic pressure, pH, and electrical conductivity inside and outside the cell, thereby interfering with the exchange of substances and signal transmission inside and outside the cell, leading to abnormal seedling growth or even death. These dead seedlings may carry genetic mutations that are highly useful to scientists and breeders. Therefore, research into methods to increase the survival rate of rice seedlings after gamma-ray irradiation and reduce the loss of mutant genes is of great practical significance and research value. Currently, no scientific methods exist for this purpose, either domestically or internationally. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention aims to provide a method for using brassinolide (hereinafter abbreviated as BR) in improving the survival rate and / or promoting the growth of radiation-induced rice seedlings.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides the use of brassinolide in improving the survival rate of radiation-induced rice seedlings and / or promoting the growth of radiation-induced rice seedlings.

[0007] Preferably, the application includes any one or more of the following (1) to (4):

[0008] (1) increasing the fresh weight and / or dry weight of the induced seedlings;

[0009] (2) Increase the chlorophyll content of the induced seedlings;

[0010] (3) Increase the number of roots of induced seedlings;

[0011] (4) Increase the height and / or root length of the induced seedlings.

[0012] The present invention provides a method for improving the survival rate of radiation-induced rice seedlings and / or promoting the growth of radiation-induced rice seedlings, comprising the following steps:

[0013] soaking the radiation-mutated rice seeds; the soaking solution includes brassinolide;

[0014] The soaked seeds are cultured; and after the seeds germinate, a solution containing brassinolide is sprayed on the seeds.

[0015] Preferably, the molar concentration of brassinolide in the soaking solution is 0.001 to 5.0 μmol / L; the molar concentration of brassinolide in the spraying brassinolide solution is 0.1 to 0.2 μmol / L.

[0016] Preferably, the number of sprayings after the seeds germinate includes 2 times; the first spraying is carried out on the 6th to 8th day after germination; the second spraying is carried out on the 12th to 15th day after germination, and the interval between the two sprayings is 5 to 7 days.

[0017] Preferably, the amount of each spraying of the brassinolide solution with a concentration of 0.1 to 0.2 μmol / L is 15 to 25 kg / mu to ensure that all seedlings can be sprayed.

[0018] Preferably, the soaking time is 20 to 24 hours; the soaking temperature is 25 to 32°C.

[0019] Preferably, the rice includes indica rice and / or japonica rice.

[0020] Preferably, the culturing of the seeds includes hydroponic culture; the nutrient solution for hydroponic culture includes Yoshida rice nutrient solution.

[0021] The present invention provides an application of the method described in the above technical solution in any one or more of the following (1) to (4):

[0022] (1) increasing the fresh weight and / or dry weight of the induced seedlings;

[0023] (2) Increase the chlorophyll content of the induced seedlings;

[0024] (3) Increase the number of roots of induced seedlings;

[0025] (4) Increase the height and / or root length of the induced seedlings.

[0026] Beneficial effects of the present invention:

[0027] The present invention provides the use of brassinolide in improving the survival rate and / or promoting the growth of radiation-induced rice seedlings. Radiation treatment of rice seeds to create mutants is one of the important ways to innovate germplasm resources. However, irradiating rice seeds can affect their physiological and metabolic activities, leading to abnormal seedling growth or even death, which in turn significantly reduces the mutagenesis efficiency. The present invention uses the plant growth regulator brassinolide to treat rice seeds at different growth stages after radiation treatment, which can improve the survival rate of induced seedlings, reduce the loss of mutant genes, and thus improve the radiation mutagenesis efficiency. The results of the examples show that after irradiation treatment of rice seeds, the present invention uses a brassinolide solution for pre-sowing soaking and post-sowing spraying treatment, which significantly improves the survival rate of germinating rice seedlings after radiation treatment; further, it increases the fresh weight and / or dry weight of the induced seedlings; increases the chlorophyll content of the induced seedlings; increases the number of roots of the induced seedlings; and increases the height and / or root length of the induced seedlings. It is further proved that the brassinolide can not only improve the survival rate of the radiation-induced rice seedlings, but also promote the growth of the radiation-induced rice seedlings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a graph showing the effect of soaking seeds with different concentrations of BR on the germination of Zhe 1613 rice seeds after radiation treatment;

[0030] Figure 2 This is a graph showing the effect of soaking seeds with different concentrations of BR on the germination of Zhejing 100 rice seeds after radiation treatment;

[0031] Figure 3 The growth diagram of Zhe 1613 seeds after being soaked in 5.0 μmol / L BR solution and cultured for 2 days;

[0032] Figure 4 This is a graph showing the effect of different concentrations of BR soaking and spraying at the seedling stage on the survival rate of Zhe 1613 rice seedlings after radiation treatment;

[0033] Figure 5 This is a graph showing the effects of different concentrations of BR soaking and spraying at the seedling stage on the survival rate of Zhejing 100 rice seedlings after radiation treatment;

[0034] Figure 6This is a graph showing the effects of soaking seeds with different concentrations of BR and spraying them at the seedling stage on the seedling height and root length of Zhe 1613 rice after radiation treatment;

[0035] Figure 7 This is the effect of soaking seeds with different concentrations of BR and spraying at the seedling stage on the seedling height and root length of Zhejing 100 rice after radiation treatment;

[0036] Figure 8 This is the effect of soaking seeds with different concentrations of BR and spraying at the seedling stage on the root number of Zhe 1613 rice seedlings after radiation treatment;

[0037] Figure 9 This is the effect of soaking seeds with different concentrations of BR and spraying at the seedling stage on the root number of Zhejing 100 rice seedlings after radiation treatment;

[0038] Figure 10 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the fresh weight of Zhe 1613 seedlings after radiation treatment in Example 1;

[0039] Figure 11 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the dry weight of Zhe 1613 seedlings after radiation treatment in Example 1;

[0040] Figure 12 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the fresh weight of Zhejing 100 seedlings after radiation treatment in Example 2;

[0041] Figure 13 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the dry weight of Zhejing 100 seedlings after radiation treatment in Example 2;

[0042] Figure 14 This is the effect of different concentrations of BR soaking and spraying at the seedling stage on the chlorophyll content of Zhe 1613 seedlings after radiation treatment;

[0043] Figure 15 This is the effect of different concentrations of BR soaking and spraying at the seedling stage on the chlorophyll content of Zhejing 100 seedlings after radiation treatment;

[0044] Figure 16 This is a graph showing the effect of different concentrations of BR soaking on the survival rate of Zhe 1613 rice seedlings after radiation treatment in Comparative Example 1;

[0045] Figure 17 This is a graph showing the effect of soaking seeds with different concentrations of BR on the survival rate of Zhejing 100 rice seedlings after radiation treatment in Comparative Example 2. DETAILED DESCRIPTION

[0046] The present invention provides the use of brassinolide in improving the survival rate of radiation-induced rice seedlings and / or promoting the growth of radiation-induced rice seedlings.

[0047] Radiation treatment of rice seeds to create mutants is one of the important ways to innovate germplasm resources. However, radiation of rice seeds can affect their physiological metabolic activities, leading to abnormal growth of seedlings or even death. In the present invention, the brassinolide, as a plant growth regulator, can enhance plant antioxidant capacity, improve plant osmotic regulation, increase plant leaf water potential, increase leaf water content, reduce water demand and transpiration intensity, thereby maintaining cell turgor, alleviating dehydration stress, and improving the water status of plant cells; it can also improve various stress resistances such as drought resistance, salt resistance, and cold resistance in various plants. The present invention applies the brassinolide to the planting of radiation-treated rice seeds. The plant growth regulator brassinolide is used to treat the rice seeds at different stages after radiation treatment, thereby increasing the survival rate of the induced seedlings and reducing the loss of mutant genes, thereby improving the efficiency of radiation mutagenesis.

[0048] In the present invention, the application preferably includes any one or more of the following (1) to (4): (1) increasing the fresh weight and / or dry weight of the induced seedlings; (2) increasing the chlorophyll content of the induced seedlings; (3) increasing the number of roots of the induced seedlings; (4) increasing the height and / or root length of the induced seedlings.

[0049] In the present invention, brassinolide is beneficial for increasing the fresh weight and / or dry weight of radiation-induced rice seedlings. The present invention demonstrates, through examples, that treating rice seeds with a semi-lethal dose of radiation, followed by pre-sowing soaking and post-sowing spraying of the irradiated seeds with brassinolide, can increase the fresh and dry weight of the aboveground stems, leaves, and underground roots of the rice seedlings.

[0050] In the present invention, brassinolide is beneficial for increasing the chlorophyll content of radiation-induced rice seedlings. The present invention demonstrates, through examples, that treating rice seeds with a semi-lethal dose of radiation, followed by soaking the irradiated seeds before sowing and spraying them after sowing, can increase the chlorophyll a and chlorophyll b content of the rice seedlings, thereby increasing the total chlorophyll content.

[0051] In the present invention, brassinolide is beneficial for increasing the root number of radiation-induced rice seedlings. The present invention demonstrates, through examples, that treating rice seeds with a semi-lethal dose of radiation, followed by soaking the irradiated seeds before sowing and spraying them after sowing, can increase the root number of radiation-induced rice seedlings.

[0052] In the present invention, brassinolide is beneficial for increasing the seedling height and / or root length of radiation-induced rice seedlings. The present invention demonstrates, through examples, that treating rice seeds with a semi-lethal dose of radiation, followed by soaking the irradiated seeds before sowing and spraying them after sowing, can increase the seedling height and root length of the rice seedlings.

[0053] The present invention provides a method for improving the survival rate of radiation-induced rice seedlings and / or promoting the growth of radiation-induced rice seedlings, comprising the following steps:

[0054] soaking the radiation-mutated rice seeds; the soaking solution includes brassinolide;

[0055] The soaked seeds are cultured; and after the seeds germinate, a solution containing brassinolide is sprayed on the seeds.

[0056] The present invention soaks the rice seeds undergoing radiation mutagenesis. In the present invention, the rice seeds preferably include indica rice seeds and / or japonica rice seeds. In the present invention, the indica rice seeds preferably include Zhe 1613 seeds; the japonica rice seeds preferably include Zhe Jing 100 seeds. The present invention does not specifically limit the method for radiation mutagenesis of the rice seeds; conventional radiation mutagenesis methods in the art may be employed. In the present invention, the radiation mutagenesis method preferably includes using cesium 137 or cobalt 60 as a radiation source, more preferably cesium 137 as a radiation source. In the present invention, the radiation dose is preferably a median lethal dose. When radiation mutagenesis is performed on indica rice seeds, the radiation dose is preferably 350 to 450 Gy, more preferably 427 Gy; when radiation mutagenesis is performed on japonica rice seeds, the radiation dose is preferably 250 to 350 Gy, more preferably 318 Gy. When the radiation mutagenesis is carried out in the present invention, the radiation mutagenesis dose rate is preferably 1 Gy / min; when the radiation mutagenesis is carried out in the present invention, the rice is preferably irradiated at a position 80 cm away from the center of the source rod.

[0057] After obtaining the radiation-mutated rice seeds, the present invention preferably soaks the seeds. In the present invention, the molar concentration of brassinolide in the soaking solution is preferably 0.001-5.0 μmol / L, more preferably 0.01-1.0 μmol / L, and more preferably 0.01-0.1 μmol / L. During the soaking process of the present invention, the soaking solution preferably completely immerses the seeds so that the seeds can still be completely immersed in the soaking solution after swelling. In the present invention, the mass volume ratio of the seeds to the soaking solution is preferably 1 g: (2-5) mL, more preferably 1 g: (2.5-3.5) mL, and most preferably 1 g: 3 mL. The soaking temperature of the present invention is preferably 25-32°C, more preferably 26-30°C, and more preferably 28°C; the soaking time is preferably 20-24 h, and more preferably 23-24 h. The present invention soaks irradiated seeds in a solution containing brassinolide. This not only promotes seed germination, but also allows brassinolide to penetrate the seeds, thereby regulating seed physiology and promoting the growth of irradiated seeds. During the soaking process, the present invention strictly controls the soaking time to within 24 hours to prevent the seeds from being immersed in water for too long, which can cause the cells to undergo anaerobic respiration due to lack of oxygen. The products of this anaerobic respiration include alcohol and carbon dioxide. The accumulation of alcohol is toxic to seed cells, causing cell poisoning, which in turn affects normal seed development and may ultimately lead to improper germination or seedling death. After soaking, the present invention preferably rinses the soaked seeds; the number of rinses is preferably two, and the rinsing is preferably performed with purified water.

[0058] After soaking and rinsing, the soaked seeds are cultured in the present invention. The present invention does not specifically limit the culture method; any conventional culture method in the art can be used. In the present invention, the culture preferably includes germination culture and hydroponic culture. The present invention does not specifically limit the germination culture method; any conventional germination culture method in the art can be used. In the present invention, the germination culture method preferably includes placing the seeds in a germination box for germination culture. In the present invention, the germination box preferably measures 120 mm x 120 mm x 50 mm in length, width, and height. The bottom of the germination box is preferably lined with three sheets of filter paper. An appropriate amount of purified water is added to the filter paper to ensure the seeds have the necessary moisture for germination. During germination culture, the seeds are preferably evenly spaced in the germination box, with sufficient distance between the seeds to ensure adequate water exposure, uniform water absorption, and good growth. In the present invention, each germination box preferably contains 100 seeds. The germination culture temperature is preferably 26-30°C, more preferably 28°C, and the germination culture duration is preferably 2 days. The invention obtains germinated seeds by performing germination culture on the seeds.

[0059] After obtaining the germinated seeds, the present invention preferably sprays the seeds with a solution containing brassinolide twice after germination. After obtaining the germinated seeds, the present invention does not specifically limit the method for culturing the germinated seeds, and any conventional culturing method in the art can be used. In the present invention, the method for culturing the germinated seeds preferably includes hydroponic cultivation. The present invention does not specifically limit the method for hydroponic cultivation, and any conventional hydroponic cultivation method in the art can be used. In the present invention, the method for hydroponic cultivation preferably includes transferring the germinated seeds to a hydroponic box for hydroponic cultivation. In the present invention, the hydroponic box preferably includes a black hydroponic box measuring 86 mm × 126 mm × 114 mm; the black hydroponic box contains 96 holes; the holes are arranged in an 8-hole × 12-hole arrangement. The present invention uses a black hydroponic box to simulate dark conditions, which, on the one hand, makes the growth environment of the seedling roots consistent with the dark environment in the soil, and, on the other hand, prevents algae from breeding and affecting root growth. In the present invention, the hydroponic culture nutrient solution preferably includes Yoshida rice nutrient solution; the working concentration of the Yoshida rice nutrient solution is preferably 232 to 464 mg / L; the pH value of the Yoshida rice nutrient solution is preferably 5.8±0.1; and the Yoshida rice nutrient solution is preferably replaced every 5 days during the hydroponic culture process. In the hydroponic culture process of the present invention, the hydroponic culture is preferably carried out using Yoshida rice nutrient solution with a working concentration of 232 mg / L for the first 20 days of hydroponic culture; and after the 21st day of hydroponic culture, the hydroponic culture is replaced with Yoshida rice nutrient solution with a working concentration of 464 mg / L.

[0060] The present invention preferably sprays a solution containing brassinolide during the hydroponic culture process. In the present invention, the molar concentration of brassinolide in the brassinolide solution for spraying is preferably 0.1-0.2 μmol / L, more preferably 0.1 μmol / L. In the present invention, the number of sprayings after seed germination is preferably two: a first spray and a second spray. The first spray is preferably performed on the 6th to 8th day after germination, more preferably on the 7th day; the second spray is preferably performed on the 12th to 15th day after germination, more preferably on the 14th day. Alternatively, the first spray is preferably performed on the 6th to 8th day after seedling cultivation begins, and the second spray is preferably performed on the 12th to 15th day after seedling cultivation begins. The interval between sprayings is preferably 5-7 days, more preferably 7 days. Each spraying of the brassinolide solution is preferably performed after sunset, more preferably around 8:00 PM. When spraying the present invention, the amount used for each spraying is preferably 2 mL per 96-well box. When the present invention is applied to field seedling cultivation, when the seedlings after germination are sprayed with a solution containing brassinolide, the amount of brassinolide solution used for each spraying can be 15-25 kg / mu, or 20 kg / mu. When spraying the present invention, it is preferred to ensure that each seedling is sprayed.

[0061] After the rice seeds are cultured for 28 days using the method described in the technical solution, the survival rate of the obtained rice seedlings is stable and the rice seedlings can be transplanted to the field.

[0062] The present invention adopts the above method to cultivate rice radiation-induced seedlings, that is, soaking the radiation-treated seeds before sowing and spraying BR treatment after sowing can significantly improve the survival rate of radiation-induced seed seedlings, increase the fresh weight and / or dry weight of the induced seedlings, increase the chlorophyll content of the induced seedlings, increase the number of roots of the induced seedlings, and increase the seedling height and / or root length of the induced seedlings.

[0063] The present invention provides the use of the method described in the above technical solution for improving the survival rate and / or promoting the growth of radiation-induced rice seedlings. The present invention utilizes the method to treat rice seeds at different growth stages after radiation treatment with the plant growth regulator brassinolide, thereby increasing the survival rate of induced seedlings, reducing the loss of mutant genes, and thus improving the efficiency of radiation mutagenesis. The results of the examples show that, after irradiation of rice seeds, the present invention utilizes a brassinolide solution for pre-sowing soaking and post-sowing spraying, significantly improving the survival rate of the irradiated rice seeds. Furthermore, the method increases the fresh weight and / or dry weight of the induced seedlings, the chlorophyll content of the induced seedlings, the number of roots in the induced seedlings, and the height and / or root length of the induced seedlings. This further demonstrates that brassinolide not only improves the survival rate of radiation-induced rice seedlings but also promotes their growth.

[0064] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0065] Example 1

[0066] A method for improving the survival rate and / or promoting the growth of radiation-induced rice seedlings comprises the following steps:

[0067] 1. The rice variety used for the test was the indica rice Zhe 1613.

[0068] 2. Radiation treatment: Select rice seeds with normal germination rate and irradiate them with cesium 137( 137 Cs) was a radioactive source with an intensity of 21,000 Curies. Rice plants were irradiated at a distance of 80 cm from the center of the source rod at a dose rate of 60 Gy / h (or 1 Gy / min), where dose = dose rate x time. Test seeds were irradiated with a semi-lethal dose of 427 Gy.

[0069] 3. The following experiment was conducted on seeds irradiated at the above doses. The irradiated seeds were treated with brassinolide (BR) before sowing and then sprayed after sowing. Six experimental groups were divided, each containing 600 seeds. These groups were designated C1pt, C2pt, C3pt, C4pt, C5pt, and CK.

[0070] In treatment C1pt, seeds were soaked in a 0.001 μmol / L BR solution before sowing and sprayed with the BR solution after sowing; in treatment C2pt, seeds were soaked in a 0.01 μmol / L BR solution before sowing and sprayed with the BR solution after sowing; in treatment C3pt, seeds were soaked in a 0.1 μmol / L BR solution before sowing and sprayed with the BR solution after sowing; in treatment C4pt, seeds were soaked in a 1.0 μmol / L BR solution before sowing and sprayed with the BR solution after sowing; and in treatment C5pt, seeds were soaked in a 5.0 μmol / L BR solution before sowing and sprayed with the BR solution after sowing. Each experimental group was sprayed with a 0.1 μmol / L BR solution twice after sowing, with an interval of 7 days between sprayings. In group CK, seeds were soaked in distilled water instead of BR solution before sowing, and an equal volume of distilled water was sprayed simultaneously with the BR solution after sowing.

[0071] The specific steps are as follows:

[0072] (1) At room temperature of 28°C ± 2°C, 600 seeds irradiated with the above-mentioned doses were randomly selected from each treatment and soaked in BR solutions of different concentrations (0.001 μmol / L, 0.01 μmol / L, 0.1 μmol / L, 1.0 μmol / L, and 5.0 μmol / L) for 24 h. The ratio of seeds to BR solution was 1 g: 3 mL (w / v). A control group (CK group) was also used, in which seeds were soaked in distilled water for the same time and volume as the other experimental groups.

[0073] (2) The rice seeds soaked in different concentrations of BR and the CK group were rinsed twice with purified water. They were then placed in a germination box with a length, width, and height of 120 mm × 120 mm × 50 mm. Three pieces of filter paper were placed at the bottom of the germination box. An appropriate amount of purified water was added. 100 rice seeds were randomly and evenly placed in each box. A sufficient distance was maintained between the seeds to ensure that all seeds were fully exposed to water, absorbed water uniformly, and grew well. 200 seeds were used for each treatment, repeated three times, and randomly arranged, for a total of 600 seeds. After 2 days, for each concentration treatment, the germinated seeds were transferred to two 96-well (8 wells * 12 wells) black plastic hydroponic boxes (length 12.6 cm × width 8.6 cm × height 11.4 cm), and 0.9 L of Yoshida rice nutrient solution with a concentration of 232 mg / L was poured into the box. The pH of the nutrient solution was 5.8±0.1. The nutrient solution was replaced every 5 days. After the 21st day of culture in the hydroponic box, the Yoshida rice nutrient solution with a concentration of 464 mg / L was replaced.

[0074] (3) The seedlings treated with C1pt, C2pt, C3pt, C4pt, and C5pt were sprayed with 0.1 μmol / LBR solution once each on the 7th and 14th day after germination (the 7th and 14th day after germination refers to the 7th and 14th day after the seeds began to be cultured, that is, when the seeds were placed in the germination box for culture). When spraying on the 7th and 14th day after germination, each treatment group was sprayed at 20:00 on each spraying day, and 2 mL was sprayed per 96-well box each time. When the CK group was sprayed with distilled water, the spraying time and volume were the same as those of the other experimental groups.

[0075] (4) The seedlings of each experimental group were cultured in a KBW400 growth chamber at a temperature of 28 ± 1 °C and a controlled photoperiod of 12 h (with a photon flux density of 360 μmol·m -2 ·s -1 ) and 12 hours of darkness, with a relative humidity of 75% ± 5%. After 21 days of seedling growth in black plastic hydroponic boxes, 50 surviving seedlings were sampled for growth and physiological parameters. The remaining seedlings were used to assess survival rate. Moldy seeds or seedlings were removed daily.

[0076] 4. The survival rate of rice seedlings on the 3rd, 7th, 14th, 21st and 28th days of culture (starting from the time the seeds were placed in the germination box) was counted.

[0077] 5. The seedling height, root length, root number, fresh weight and dry weight of stems and leaves (aboveground part) and roots (belowground part) of rice seedlings cultured for 21 days (calculated from the time the seeds were placed in the germination box) were measured. The chlorophyll a, b content and total chlorophyll content of the seedlings were also measured.

[0078] Example 2

[0079] A method for improving the survival rate of rice seedlings induced by radiation, comprising the following steps: the test rice variety is the japonica rice Zhejing 100; the radiation treatment of the japonica rice Zhejing 100 is as follows: selecting rice seeds with a normal germination rate, irradiating them with cesium 137( 137 Cs) was a radioactive source with an intensity of 21,000 Curies. Rice plants were irradiated at a distance of 80 cm from the center of the source rod at a dose rate of 60 Gy / h (or 1 Gy / min), where dose = dose rate x time. Test seeds were irradiated with a semi-lethal dose of 318 Gy.

[0080] Other steps are the same as in Example 1.

[0081] Application Example 1

[0082] 1. Effects of soaking seeds with different concentrations of BR solution on germination of irradiated rice seeds

[0083] Effects of soaking seeds with different concentrations of BR solution on germination of irradiated rice seeds Figures 1-2 As shown, Figure 1 and Figure 2 This is a photo of seeds that were soaked for 24 hours and then cultured in a germination box for 2 days. Figure 1 This figure shows the effect of soaking seeds with different concentrations of BR solution on the germination of Zhe 1613 rice seeds after radiation treatment; Figure 2 This is a graph showing the effect of soaking seeds with different concentrations of BR solution on the germination of Zhejing 100 rice seeds after radiation treatment. Figure 1 and Figure 2 The corresponding BR seed soaking concentrations from left to right are 0, 0.001μmol / L, 0.01μmol / L, 0.1μmol / L,

[0084] The growth of Zhe 1613 seeds after soaking in 1.0μmol / L and 5.0μmol / L BR solution for 2 days is shown in the figure. Figure 3 shown.

[0085] Depend on Figures 1-2It can be seen that soaking seeds with BR solution significantly affects the morphology of seed roots during seed germination. At high concentrations, the seed roots are obviously twisted. The effect on the japonica rice variety Zhejiang Jing 100 is more obvious than that on the indica rice variety Zhejiang 1613. This indicates that soaking seeds with high concentrations of BR will curb the germination process of seeds after irradiation. Usually, the concentration of BR used in the regulation of rice drought resistance, cold resistance, etc. is about 1.0 μmol / L. According to our analysis of the biological effects of rice seed mutagenesis, BR application was carried out to obtain relevant results. The present invention uses 0.01-0.1 μmol / L BR solution to soak irradiated seeds, which has a better effect. If the concentration is too high, for example, 5.0 μmol / L will cause the seed roots to be damaged by the drug and grow poorly, and it will also have an adverse effect on germination, such as Figure 3 The phenomenon seen in the study is slow growth and twisted roots.

[0086] 2. The results of the effects of soaking seeds at different concentrations and spraying BR at the seedling stage on the survival rate of irradiated rice seeds in Example 1 and Example 2 are shown in Tables 1 and 2. Figures 4-5 shown. Figure 4 This figure shows the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the survival rate of Zhe 1613 rice seedlings after radiation treatment. Figure 5 This is a graph showing the effects of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the survival rate of Zhejing 100 rice seedlings after radiation treatment.

[0087] Table 1 Effects of different concentrations of BR soaking and spraying at the seedling stage on the survival rate of Zhe 1613 rice seedlings after irradiation

[0088] Zhejiang 1613 3d 7d 14d 21d 28d CK1 90.0±3.6a 93.7±1.5a 88.3±4.2a 55.7±2.3c 49.7±3.2c C1pt 92.3±4.5a 95.3±2.1a 87.3±3.2a 62.3±3.2b 56.0±2.6b C2pt 93.3±2.1a 94.3±3.1a 90.3±3.5a 70.3±4.2a 63.3±3.5a C3pt 90.7±2.1a 95.3±2.5a 88.7±2.5a 68.7±3.1a 61.7±2.9a C4pt 90.3±2.5a 93.3±1.5a 87.3±3.1a 61.7±3.1b 55.7±2.5b C5pt 89.7±3.1a 89.0±3.0b 85.7±4.9a 54.3±4.0c 47.7±3.5c

[0089] Note: Different letters in the table represent significant differences between different treatments in the same column at the 0.05 level, and the same letters represent no significant differences between different treatments in the same column at the 0.05 level, the same below.

[0090] Table 2 Effects of different concentrations of BR soaking and spraying at the seedling stage on the survival rate of Zhejing 100 rice seedlings after irradiation

[0091]

[0092]

[0093] Depend on Figures 4-5Comparative analysis revealed that after pre-sowing seed soaking and two post-sowing sprays of 0.1 μmol / L BR at the seedling stage, the rate of rice seedling mortality following irradiation significantly decreased for both Zhe 1613 and Zhejing 100, ultimately resulting in an increase in seedling survival. Tables 1 and 2 show that after BR soaking and two sprays, the survival rate of rice seedlings at 28 days after irradiation increased by 12.68%, 27.36%, 24.14%, and 12.07% compared to the CK, respectively, with the exception of the C5pt treatment, which showed no significant difference. For Zhe 1613, the C1pt, C2pt, C3pt, and C4pt treatments increased by 12.68%, 27.36%, 24.14%, and 12.07%, respectively, compared to the CK. C2pt and C3pt were significantly higher than C1pt, C4pt, and C5pt, respectively. The C5pt treatment decreased by 4.02% compared to the CK, but the differences were not significant. For Zhejing 100, the C1pt, C2pt, C3pt and C4pt treatments increased by 12.85%, 26.98%, 24.20% and 13.49% respectively compared with CK, among which C2pt and C3pt were significantly higher than C1pt, C4pt and C5pt, and C5pt treatment decreased by 6.42% compared with CK, but the difference was not significant.

[0094] 3. Effects of different concentrations of seed soaking and spraying BR at the seedling stage on seedling growth in Example 1 and Example 2

[0095] (1) The effects of soaking seeds at different concentrations and spraying BR at the seedling stage on seedling height and root length in Example 1 and Example 2 are shown in Table 3 and Figures 6-7 As shown. Figure 6 This is a graph showing the effects of soaking seeds with different concentrations of BR and spraying them at the seedling stage on the seedling height and root length of Zhe 1613 rice after radiation treatment; Figure 7 This figure shows the effects of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the seedling height and root length of Zhejing 100 rice after radiation treatment.

[0096] Table 3 Effects of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the growth of rice seedlings after irradiation treatment in Example 1 and Example 2

[0097] Zhejiang 1613 Seedling height (cm) Root length (cm) Zhejiang 100 Seedling height (cm) Root length (cm) CK 12.9±1.7a 11.1±1.1a CK 13.3±0.7a 7.1±0.4a C1pt 13.3±1.5a 11.0±0.8a C1pt 13.7±1.1a 7.1±0.3a C2pt 14.4±1.6a 11.8±0.9a C2pt 14.5±1.9a 7.4±0.5a C3pt 14.2±1.0a 11.3±1.1a C3pt 14.2±1.1a 7.0±0.5a C4pt 13.5±0.8a 10.4±0.9a C4pt 13.1±1.3a 6.7±0.3a C5pt 12.4±1.1a 10.2±1.0a C5pt 12.8±1.1a 6.8±0.4a

[0098] From Table 3 and Figures 6-7 It was found that the effects of soaking in different concentrations and spraying BR at the seedling stage on the seedling height and root length of the two varieties of seedlings were significantly promoted by the C2pt and C3pt treatments, but the differences between the treatments and compared with the control were not statistically significant.

[0099] (2) The effects of soaking seeds with different concentrations of BR and spraying BR at the seedling stage on the root number of rice seedlings after irradiation treatment in Example 1 and Example 2 are shown in Table 4 and Figures 8-9 shown. Figure 8 This is the effect of soaking seeds with different concentrations of BR and spraying at the seedling stage on the root number of Zhe 1613 rice seedlings after radiation treatment; Figure 9 This is a graph showing the effects of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the root number of Zhejing 100 rice seedlings after radiation treatment.

[0100] Table 4 Effects of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the root number of rice seedlings after radiation treatment in Example 1 and Example 2

[0101] Zhejiang 1613 Number of roots Zhejiang 100 Number of roots CK 7.9±0.6ab CK 8.8±0.5a C1pt 8.1±0.7a C1pt 8.7±0.6a C2pt 7.5±0.2ab C2pt 8.9±0.3a C3pt 7.6±0.6ab C3pt 8.8±0.8a C4pt 7.7±0.8ab C4pt 8.3±0.3ab C5pt 6.9±0.1b C5pt 7.4±0.2b

[0102] From Table 4 and Figures 8-9 It was found that soaking seeds at different concentrations and spraying BR at the seedling stage had a slight effect on the root number of seedlings. For Zhe 1613, the C1pt treatment was significantly higher than the C5pt treatment, but the difference was not significant between the treatments. The overall trend of Zhejing 100 was similar to that of Zhe 1613.

[0103] (3) The effects of soaking seeds at different concentrations and spraying BR at the seedling stage on the dry weight and fresh weight of seedlings in Example 1 and Example 2 are shown in Tables 5 to 6 and Figures 10-13 As shown. Figure 10 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the fresh weight of Zhe 1613 seedlings after radiation treatment in Example 1; Figure 11 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the dry weight of Zhe 1613 seedlings after radiation treatment in Example 1; Figure 12 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the fresh weight of Zhejing 100 seedlings after radiation treatment in Example 2; Figure 13 This is a graph showing the effect of soaking seeds with different concentrations of BR plus spraying at the seedling stage on the dry weight of Zhejing 100 seedlings after radiation treatment in Example 2.

[0104] Table 5 Effects of different concentrations of BR soaking and spraying at the seedling stage on the dry weight and fresh weight of Zhe 1613 rice seedlings after irradiation in Example 1

[0105] Zhejiang 1613 Fresh weight of aboveground parts (mg) Root fresh weight (mg) Aboveground dry weight (mg) Root dry weight (mg) CK 496.57±25.61cd 326.84±34.26ab 9.04±0.22bc 1.31±0.18ab C1pt 534.15±30.70bc 324.97±33.97ab 9.41±0.41b 1.32±0.18ab C2pt 592.08±32.70a 345.08±20.44a 10.48±0.63a 1.40±0.06a C3pt 582.36±24.82ab 309.73±37.85ab 10.50±0.44a 1.24±0.11ab C4pt 535.21±20.64bc 285.49±23.49b 9.65±0.33ab 1.13±0.11b C5pt 455.53±32.91d 273.57±22.97b 8.28±0.70c 1.09±0.09b

[0106] Table 6 Effects of different concentrations of BR seed soaking plus seedling spraying on the dry weight and fresh weight of Zhejing 100 rice seedlings after irradiation in Example 2

[0107] Zhejiang 100 Fresh weight of aboveground parts (mg) Root fresh weight (mg) Aboveground dry weight (mg) Root dry weight (mg) CK 449.93±28.52cd 312.38±23.61ab 8.79±0.26bc 1.35±0.13ab C1pt 484.33±31.17bc 328.16±17.52a 9.01±0.34b 1.41±0.05a C2pt 567.73±41.15a 341.53±23.99a 9.68±0.31a 1.47±0.14a C3pt 535.17±26.21ab 308.65±12.62ab 9.59±0.37a 1.33±0.07ab C4pt 442.59±29.70cd 284.13±19.14b 8.60±0.21bc 1.21±0.08b C5pt 410.42±30.43d 274.24±22.66b 8.34±0.27c 1.19±0.07b

[0108] From Tables 5 to 6 and Figures 10-13As can be seen, soaking seeds with different concentrations of BR and spraying them at the seedling stage increased stem and leaf fresh weight to varying degrees in treatments C1pt, C2pt, C3pt, and C4pt. For Zhe 1613, stem and leaf fresh weight increased by 7.57%, 19.23%, 17.28%, and 7.78% in the C1pt, C2pt, C3pt, and C4pt treatments, respectively, compared to the CK, while C5pt decreased by 8.26% compared to the CK. The C2pt treatment was significantly higher than the CK and C1pt, C4pt, and C5pt treatments. For Zhejing 100, stem and leaf fresh weight increased by 7.65%, 26.18%, and 18.95% in the C1pt, C2pt, and C3pt treatments, respectively, compared to the CK, while C4pt and C5pt decreased by 1.63% and 8.78% compared to the CK. Among the five treatments, C2pt was the best, followed by C3pt. That is, the appropriate concentration of seed soaking and spraying treatment makes the irradiated seedlings strong and less likely to die. There are slight differences in root fresh weight between other treatments of the two varieties, and between other treatments and CK, but the root weight decreases after higher concentration treatment, which is not conducive to root growth.

[0109] Compared with the CK, stem and leaf dry weight differed significantly among treatments. For Zhe 1613, stem and leaf dry weight increased by 4.09%, 15.93%, 16.15%, and 6.75% in the C1pt, C2pt, C3pt, and C4pt treatments, respectively, compared to the CK, while C5pt decreased by 8.41%. Treatments C2pt and C3pt were significantly higher than those in the CK, C1pt, and C5pt treatments. For Zhejing 100, stem and leaf dry weight increased by 2.50%, 10.13%, and 9.10% in the C1pt, C2pt, and C3pt treatments, respectively, compared to the CK, while C4pt and C5pt decreased by 2.16% and 5.12% compared to the CK. C2pt and C3pt were the best treatments among the five treatments. Root dry weight did not differ significantly between the other treatments and the CK, or between the other treatments, indicating similar performance between the two varieties.

[0110] (4) The effects of soaking seeds at different concentrations and spraying BR at the seedling stage on the chlorophyll content of seedlings in Example 1 and Example 2 are shown in Table 7 and Figures 14-15 shown. Figure 14 This is a graph showing the effects of soaking seeds with different concentrations of BR plus spraying brassinolide at the seedling stage on the chlorophyll content of Zhe 1613 seedlings after irradiation. Figure 15 This figure shows the effects of soaking seeds with different concentrations of BR plus spraying brassinolide at the seedling stage on the chlorophyll content of Zhejing 100 seedlings after radiation treatment.

[0111] Table 7 Effects of different concentrations of BR soaking and spraying at the seedling stage on the chlorophyll content of rice seedlings after irradiation

[0112]

[0113] Chlorophyll a, b and total chlorophyll content in seedling leaves have an important influence on photosynthesis and viability of seedlings. Figures 14-15 As shown, compared with CK, BR seed soaking and spraying treatments increased chlorophyll content in seedling leaves to varying degrees in C1pt, C2pt, C3pt, C4pt, and C5pt. For Zhe 1613, chlorophyll a content in seedling leaves treated with C1pt, C2pt, C3pt, C4pt, and C5pt increased by 10.86%, 26.86%, 18.29%, 6.86%, and 5.71%, respectively, compared with CK. C2pt treatment showed significantly higher chlorophyll a content than CK and C1pt, C4pt, and C5pt treatments. There were no significant differences between C2pt and C3pt. For Zhe 100, the chlorophyll a content of seedling leaves in C1pt, C2pt, C3pt, C4pt and C5pt treatments increased by 2.78%, 17.36%, 15.97%, 2.08% and 1.39% respectively compared with CK, and the C2pt and C3pt treatments were significantly higher than those in CK and C1pt, C4pt and C5pt treatments; there was no significant difference between C2pt and C3pt.

[0114] Regarding chlorophyll b, the chlorophyll b content in the leaves of Zhe 1613 seedlings treated with C2pt, C3pt, C4pt, and C5pt increased by 14.14%, 32.32%, 22.22%, and 2.02%, respectively, compared to the CK. The C3pt treatment showed significantly higher chlorophyll b content than the CK and C1pt and C5pt treatments. There were no significant differences between C3pt and C4pt, while C1pt showed a 3.03% decrease compared to the CK. For Zhejing 100, the chlorophyll b content in the leaves of the C1pt, C2pt, C3pt, C4pt, and C5pt treatments increased by 22.22%, 41.67%, 31.94%, 20.83%, and 19.44%, respectively, compared to the CK. The C2pt treatment showed significantly higher chlorophyll b content than the CK and C1pt, C4pt, and C5pt treatments. There were no significant differences between C2pt and C3pt.

[0115] The total amount of chlorophyll reflects the photosynthetic capacity of rice seedlings. Figure 14As shown, after soaking seeds and spraying BR, the total chlorophyll content of leaves of Zhe 1613 in the C1pt, C2pt, C3pt, C4pt, and C5pt treatments increased by 5.47%, 22.26%, 23.36%, 12.41%, and 4.38% compared with the CK, respectively. The C2pt and C3pt treatments were significantly higher than those in the CK and C1pt, C4pt, and C5pt treatments. For Zhejing 100, the C1pt, C2pt, C3pt, C4pt, and C5pt treatments increased by 8.76%, 24.89%, 20.73%, 7.37%, and 6.91% compared with the CK, respectively. The C2pt and C3pt treatments were significantly higher than those in the CK and C1pt, C4pt, and C5pt treatments. There was no significant difference between C2pt and C3pt. Overall, treatments C2pt and C3pt were optimal, consistent with the treatment effects on the fresh and dry weights of rice seedling stems and leaves, and also consistent with the survival trends of rice seedlings treated with BR soaking and spraying after irradiation. Therefore, soaking and spraying with appropriate concentrations of brassinolide improves the survival rate of rice seedlings after sublethal doses of radiation. One possible mechanism is that soaking and spraying with appropriate concentrations of brassinolide increases chlorophyll a, b, and total chlorophyll content in seedling leaves, increasing both the fresh and dry weights of the stems and leaves, and improving seedling quality. While further investigation of the underlying metabolic mechanisms is needed, this is a very useful method for improving rice seedling survival after irradiation and has broad application prospects.

[0116] Comparative Example 1

[0117] The method for improving the survival rate of radiation-induced rice seedlings is the same as that in Example 1, with the only difference being that no post-sowing spraying treatment is performed. That is, the experiment is divided into 6 test groups, each of which treats 600 irradiated seeds. The test groups are respectively recorded as C1, C2, C3, C4, C5 and CK groups. In the C1 treatment, the seeds are only soaked in a 0.001 μmol / L BR solution before sowing; in the C2 treatment, the seeds are only soaked in a 0.01 μmol / L BR solution before sowing; in the C3 treatment, the seeds are only soaked in a 0.1 μmol / L BR solution before sowing; in the C4pt treatment, the seeds are only soaked in a 1.0 μmol / L BR solution before sowing; and in the C5pt treatment, the seeds are only soaked in a 5.0 μmol / L BR solution before sowing. In the CK treatment, the seeds are not soaked in a BR solution before sowing, but in distilled water. To distinguish it from the aforementioned CK group, the CK group is recorded as CK2 here.

[0118] Comparative Example 2

[0119] The method for improving the survival rate of radiation-induced rice seedlings is the same as that in Example 2, with the only difference being that no post-sowing spraying treatment is performed. That is, the experiment is divided into 6 test groups, each of which treats 600 irradiated seeds. The test groups are respectively designated as C1, C2, C3, C4, C5, and CK groups. In the C1 treatment, the seeds are only soaked in a 0.001 μmol / L BR solution before sowing; in the C2 treatment, the seeds are only soaked in a 0.01 μmol / L BR solution before sowing; in the C3 treatment, the seeds are only soaked in a 0.1 μmol / L BR solution before sowing; in the C4pt treatment, the seeds are only soaked in a 1.0 μmol / L BR solution before sowing; and in the C5pt treatment, the seeds are only soaked in a 5.0 μmol / L BR solution before sowing. In the CK treatment, the seeds are not soaked in a BR solution before sowing, but in distilled water. To distinguish it from the aforementioned CK group, the CK group is designated as CK2 here.

[0120] Application Example 2

[0121] The effects of different concentrations of BR soaking on the survival rate of irradiated rice seeds in Comparative Examples 1 and 2 are shown in Tables 8 to 9 and Figures 16-17 shown. Figure 16 This is a graph showing the effect of different concentrations of BR soaking on the survival rate of rice seedlings after radiation treatment in Comparative Example 1; Figure 17 This is a graph showing the effect of soaking seeds with different concentrations of BR on the survival rate of rice seedlings after radiation treatment in Comparative Example 2.

[0122] Table 8 Effect of different concentrations of BR soaking on the survival rate of Zhe 1613 rice seedlings after irradiation in comparative example 1

[0123] Zhejiang 1613 3d 7d 14d 21d 28d CK2 86.0±3.6a 94.7±1.2a 87.7±3.2a 52.3±4.2c 47.7±3.5c C1 87.3±2.1a 95.7±1.5a 88.3±2.5a 57.3±1.5bc 50.3±2.3bc C2 90.7±2.3a 95.7±3.5a 89.0±3.0a 66.3±5.0a 56.0±2.6a C3 89.7±2.5a 95.7±1.5a 88.0±3.6a 63.3±3.1ab 54.3±1.5ab C4 90.0±1.0a 94.0±1.0a 86.7±2.1a 58.7±2.5bc 50.3±2.1bc C5 86.3±2.5a 87.7±2.5b 79.0±3.6b 54.0±2.6c 47.0±3.0c

[0124] Table 9 Effect of different concentrations of BR soaking on the survival rate of Zhejing 100 rice seedlings after radiation treatment in comparative example 2

[0125]

[0126]

[0127] From Tables 8 to 9 and Figures 16-17As shown, after soaking seeds with different concentrations of BR, the survival rates of Zhe 1613 seedlings in treatments C1, C2, C3, and C4 increased by 5.45%, 17.40%, 13.84%, and 5.45%, respectively, compared to CK2 after 28 days of cultivation. The differences between treatments C2 and C3 were significant. The survival rate of treatment C5 was lower than that of CK2, but the differences were not significant. For Zhejing 100, the survival rates of treatments C1, C2, C3, and C4 increased by 6.56%, 18.82%, 16.63%, and 10.07%, respectively, compared to CK2. The differences between treatments C2, C3, and C4 and CK2 were significant. The survival rate of treatment C5 was lower than that of CK2, but the differences were not significant. Due to the adverse effects of γ-ray irradiation on their physiological metabolism, the survival rate of the two varieties treated at 7 days after emergence was the highest. It began to decline after 7 days, and further declined at 14 days and 21 days. At 28 days, the survival rate of the seedlings was stable and could be transplanted to the field. Figures 16-17 ) and Tables 1 to 2 (i.e. Figures 4-5 ) showed that compared with seed soaking with BR alone, soaking with BR plus spraying BR solution at the seedling stage can significantly improve the survival rate of rice seeds after radiation treatment.

[0128] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. Application of brassinolide in improving the survival rate of radiation-induced rice seedlings; The method for improving the survival rate of radiation-induced rice seedlings comprises: soaking the radiation-induced rice seeds; the soaking solution comprises brassinolide; The rice seeds include Zhe 1613 seeds and / or Zhejing 100 seeds; the radiation mutagenesis dose is a half-lethal dose; and the molar concentration of brassinolide in the soaking solution is 0.01-0.1 μmol / L.

2. A method for improving the survival rate and / or promoting the growth of radiation-induced rice seedlings, characterized in that: The following steps are involved: soaking the radiation-mutated rice seeds; the soaking solution includes brassinolide; Cultivating the soaked seeds; spraying a solution containing brassinolide after the seeds germinate; The rice seeds include Zhe 1613 seeds and / or Zhejing 100 seeds; the radiation mutagenesis dose is a half-lethal dose; The molar concentration of brassinolide in the soaking solution is 0.01-0.1 μmol / L; the molar concentration of brassinolide in the spraying brassinolide solution is 0.1 μmol / L.

3. The method according to claim 2, characterized in that The number of sprayings after seed germination includes 2 times; the first spraying is carried out on the 6th to 8th day after germination; the second spraying is carried out on the 12th to 15th day after germination, and the interval between the two sprayings is 5 to 7 days.

4. The method according to claim 3, characterized in that The dosage of 0.1μmol / L brassinolide solution sprayed each time is 15-25kg / mu to ensure that all seedlings can be sprayed.

5. The method according to claim 2, characterized in that: The soaking time is 20 to 24 hours; the soaking temperature is 25 to 32°C.

6. The method according to claim 2, characterized in that: The seeds are cultured in a hydroponic manner; the nutrient solution for the hydroponic culture comprises Yoshida rice nutrient solution.

7. Use of the method according to any one of claims 2 to 6 in any one or more of the following (1) to (3): (1) increasing the fresh weight and / or dry weight of the induced seedlings; the fresh weight refers to the aboveground fresh weight and the root fresh weight; when increasing the aboveground fresh weight of the induced seedlings of Zhejiang 1613, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L; when increasing the root fresh weight of the induced seedlings of Zhejiang 1613, the molar concentration of brassinolide in the soaking solution is 0.01 μmol / L; when increasing the aboveground dry weight of the induced seedlings of Zhejiang 1613, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L; when increasing the root dry weight of the induced seedlings of Zhejiang 1613, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L. The molar concentration is 0.01 μmol / L; when the fresh weight of the aboveground part of the Zhejing 100 mutant seedlings is increased, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L; when the fresh weight of the roots of the Zhejing 100 mutant seedlings is increased, the molar concentration of brassinolide in the soaking solution is 0.01 μmol / L; when the dry weight of the aboveground part of the Zhejing 100 mutant seedlings is increased, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L; when the dry weight of the roots of the Zhejing 100 mutant seedlings is increased, the molar concentration of brassinolide in the soaking solution is 0.01 μmol / L; (2) Increase the chlorophyll content of the induced seedlings; (3) Improving the height and / or root length of the induced seedlings; when increasing the height of the induced seedlings of Zhejiang 1613, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L; when increasing the root length of the induced seedlings of Zhejiang 1613, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L; when increasing the height of the induced seedlings of Zhejiang Jing 100, the molar concentration of brassinolide in the soaking solution is 0.01 to 0.1 μmol / L; when increasing the root length of the induced seedlings of Zhejiang 1613, the molar concentration of brassinolide in the soaking solution is 0.01 μmol / L.

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