Nutrient solution for culturing Guizhou indica rice variety 'Guihong No.1' as well as application and culture method thereof

Abstract

The invention relates to the technical field of rice planting methods, in particular to a nutrient solution for culturing Guizhou indica rice variety 'Guizhou Red No.1' as well as application and a culture method of the nutrient solution. According to the invention, a nutrient solution specially aiming at 'Guihong No.1' is researched and determined, the nutrient solution is added with micromolecular substances and Br with the final concentration of 0.1-0.6 [mu] M, GABA with the final concentration of 0.3-0.9 mM, melatonin with the final concentration of 0.5-5 [mu] M and salicylic acid with the final concentration of 10-20 [mu] M, and the nutrient solution specially aiming at 'Guihong No.1' can effectively improve the plant height, the biomass (fresh weight), the nitrogen content, the chlorophyll content and the dry weight of a single plant of 'Guihong No.1'. The nutrient solution provided by the invention can solve the technical problem of lack of an effective culture method in the prior art, and can better promote large-scale, intensive and factory planting management and large-area popularization and application of indica rice varieties in Guizhou by utilizing synergistic interaction and advantage complementation among different treatment modes.

Description

Technical Field

[0001] This application relates to the technical field of rice cultivation methods, specifically a nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" and its application and cultivation method. Background Technology

[0002] Rice is one of the world's most important food crops, feeding nearly 50% of the world's population. China is a major rice producer and consumer, with about two-thirds of its population relying on rice as a staple food. For a long time, China has been committed to rice breeding, focusing on improving both yield and quality.

[0003] "Guihong No. 1" is one of Guizhou's distinctive indica red rice varieties and a representative of Guizhou's characteristic functional rice. Guizhou's plateau and mountainous terrain has a complex ecosystem and often faces adverse conditions such as autumn wind damage and drought. "Guihong No. 1" exhibits good cold resistance and resilience, with long, slender grains rich in amino acids, iron, selenium, and other trace elements, as well as anthocyanins. It possesses a unique aroma and excellent eating quality. These characteristics perfectly align with the requirements of modern agricultural development, therefore, its planting area should be expanded.

[0004] However, traditional rice transplanting methods have been gradually replaced by factory-style seedling cultivation. Exploring a planting and cultivation method suitable for cultivating Guizhou indica rice "Guihong No. 1" is conducive to the further large-scale, intensive and factory-style planting of rice varieties, and can be promoted and applied in different ecological zones of Guizhou, further tapping the growth and yield potential of rice and promoting the promotion of Guizhou's specialty rice.

[0005] Currently, the factory-based seedling cultivation of "Guihong No. 1" has encountered problems such as unstable growth, poor disease resistance, and low yield. Therefore, it is necessary to explore a suitable planting and cultivation method for high-quality indica rice "Guihong No. 1", which is particularly important for promoting the application and popularization of high-quality rice. Summary of the Invention

[0006] To address the aforementioned technical problems in the existing technology, this application provides a nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1," along with its application and cultivation method, as detailed below: The Guizhou-specific indica rice variety "Guihong No. 1" is a representative indica rice variety of Guizhou. Its growth period is 151 days, and it belongs to the medium-late maturing type. The seeds are long, with red seed coats, very few short awns, and colorless awn tips.

[0007] A nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" contains different types of amino acids. The types and final concentrations of the amino acids are one of the following three: 0.1~0.5mM arginine + 0.09~0.4mM alanine + 0.08~0.3mM phenylalanine + 0.1~0.5mM threonine + 0.09~0.6mM proline; 0.1~0.6mM asparagine + 0.05~0.5mM alanine + 0.05~0.5mM methionine + 0.05~0.5mM tryptophan + 0.1~0.6mM serine; 0.08~0.5mM glutamine + 0.1~0.6mM aspartic acid + 0.1~0.6mM tyrosine + 0.05~0.5mM cysteine ​​+ 0.1~0.5mM glycine.

[0008] Furthermore, the preferred amino acid types and final concentrations are: 0.15mM arginine + 0.1mM alanine + 0.1mM phenylalanine + 0.1mM threonine + 0.1mM proline, 0.15mM asparagine + 0.1mM alanine + 0.1mM methionine + 0.15mM tryptophan + 0.2mM serine, and 0.2mM glutamine + 0.2mM aspartic acid + 0.2mM tyrosine + 0.1mM cysteine ​​+ 0.1mM glycine.

[0009] Furthermore, the amino acid composition and final concentration are 0.08~0.5mM glutamine + 0.1~0.6mM aspartic acid + 0.1~0.6mM tyrosine + 0.05~0.5mM cysteine ​​+ 0.1~0.5mM glycine + 0.08~0.5mM glutamine + 0.1~0.6mM aspartic acid + 0.1~0.6mM tyrosine + 0.05~0.5mM cysteine ​​+ 0.1~0.5mM glycine.

[0010] Furthermore, the nutrient solution also contains 0.1~0.6 μM Br, 1~6 mM Vitamin C, 0.3~0.9 mM MGA B, 0.5~5 μM Melatonin, and 10~20 μM Salicylic Acid.

[0011] Furthermore, the preferred proportions of each component are: 0.1 μM Br, 1 mM Vitamin C, 0.5 mM GABA, 1 μM Melatonin, and 15 μM Salicylic Acid.

[0012] Furthermore, the nutrient solution contains 63,000 mg / L NaH2PO4•2H2O, 111,625 mg / L K2SO4, 39.55 mg / L CaCl2, 506,250 mg / L MgSO4•7H2O, 1,761 mg / L MnCl2•4H2O, 0.127 mg / L Na2MoO4•2H2O, 1,168 mg / L H3BO4, 0.044 mg / L ZnSO4•7H2O, 0.039 mg / L CuSO4•5H2O, 15,000 mg / L EDTA-Na2, and 11,140 mg / L FeSO4•7H2O.

[0013] Furthermore, the final nitrogen concentration in the nutrient solution is 1 mM.

[0014] The nutrient solution described above is used in the cultivation of the Guizhou specialty indica rice variety "Guihong No. 1". Furthermore, the application in the cultivation of "Guihong No. 1" specifically involves improving the biomass, plant height, tiller number, nitrogen content, and chlorophyll content of the plant.

[0015] The application of the nutrient solution used to cultivate the Guizhou specialty indica rice variety "Guihong No. 1" in improving rice quality and breeding.

[0016] A method for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" involves using the nutrient solution described above to cultivate rice seedlings at the three-leaf stage, wherein the rice seedlings are of the variety "Guihong No. 1".

[0017] Furthermore, rice seedlings at the three-leaf stage are obtained by the following method: rice seeds are hydroponically cultured until the first incomplete leaf appears; the water is replaced with ordinary rice nutrient solution, and the seedlings are cultured until the tillering stage to obtain rice seedlings at the tillering stage.

[0018] Compared with the prior art, the technical effects created by this application are reflected in: (1) This application focuses on the Guizhou specialty indica rice variety “Guihong No. 1” and has determined a nutrient solution formula with a certain promoting effect. When planting “Guihong No. 1”, the rice nutrient solution with the final concentration of nutrient solution plus 0.5mM GABA, 15μM salicylic acid, 1μM melatonin and 0.1μM Br can effectively promote the planting effect of “Guihong No. 1”, especially in terms of the increase in biomass, plant height, number of tillers, nitrogen content and chlorophyll content of “Guihong No. 1” plants.

[0019] (2) This application provides a nutrient solution formula and cultivation method suitable for the growth and development of “Guihong No. 1”, which is expected to solve the problem of “Guihong No. 1”’s adaptability to different ecological zones, accelerate the process of factory seedling cultivation, and realize the large-scale, intensive planting management and large-scale promotion of “Guihong No. 1”. Attached Figure Description

[0020] Figure 1 The statistical results and phenotypic images of plant height, fresh weight, root length, number of tillers, and dry weight of "Guihong No. 1" under the single amino acid combination treatment group and the single small molecule substance combination treatment conditions of Example 1 of the present invention are shown (statistical results are expressed as mean ± SD, n = 10; Duncan's test was used to analyze the significance of differences, and the data are marked with lowercase letters above them. In the same statistical graph, different lowercase letters indicate significant differences between them, p < 0.05; the same lowercase letters indicate that the significance level is consistent).

[0021] Figure 2 , Figure 3 The statistical results and phenotypic images of plant height, fresh weight, root length, number of tillers, and dry weight of "Guihong No. 1" under the combined treatment conditions of amino acids and small molecules in Example 1 of this invention are shown below (statistical results are expressed as mean ± SD, n = 10; Duncan's test was used for significance analysis, and lowercase letters are marked above the data. In the same statistical graph, different lowercase letters indicate significant differences, p < 0.05; the same lowercase letters indicate consistent significance levels).

[0022] Figure 4 The results of the nitrogen percentage test of "Guihong No. 1" in Example 2 of the present invention are as follows (statistical results are expressed as mean±SD, n=3;**, p<0.01;*, p<0.05).

[0023] Figure 5 The results of chlorophyll content, chlorophyll a content and chlorophyll b content of "Guihong No. 1" in three embodiments of the present invention are as follows (statistical results are expressed as mean±SD, n=3;**, p<0.01;*, p<0.05). Detailed Implementation

[0024] The technical solution of this application will be further defined below with reference to specific implementation methods, but the scope of protection is not limited to the description.

[0025] Currently, the factory-based seedling cultivation of "Guihong No. 1" has encountered problems such as unstable growth, poor disease resistance, and low yield. Therefore, it is necessary to explore a suitable planting and cultivation method for high-quality indica rice "Guihong No. 1", which is particularly important for promoting the application and popularization of high-quality rice.

[0026] Example 1: Effects of different amino acid treatments on the growth and development of “Guihong No. 1”.

[0027] Rice Variety: The "Guihong No. 1" variety involved in this project is a characteristic red indica rice variety from Guizhou. The rice seeds used as biological material in subsequent experiments are seeds of the "Guihong No. 1" variety, a local characteristic indica rice from Guizhou. It is a representative indica rice variety of Guizhou, with a growth period of 151 days, belonging to the medium-late maturing type. The seeds are long, with a red seed coat, very few short awns, and colorless glume tips. The seeds of "Guihong No. 1" were collected from Guizhou Liping County Yufeng Rice Industry Co., Ltd., and are currently preserved in the Plant Hormone and Nutritional Molecular Regulation Laboratory of the Rice Industry Technology Research Institute of Guizhou University. The applicant promises to release the above-mentioned rice genetic resources to the public within twenty years from the date of application.

[0028] Rice seed soaking: Soak rice seeds in 0.6% dilute nitric acid for 6-8 hours.

[0029] Rice seed culture: After soaking, rinse the seeds with deionized water 3 to 5 times, divide them into petri dishes, add appropriate purified water, and place them in an incubator at 37℃ for culture, changing the water 1 to 2 times a day.

[0030] Hydroponics: After the seeds germinate, wait until the sprouts grow to 1-2 cm, then sow them in a 96-well plate and place them in a 4 L culture box with clean water for cultivation until the first incomplete leaf appears. Then, replace the water with ordinary rice nutrient solution and cultivate until the 3-leaf stage. Then, transplant them into 15 L culture pots, add 12 L of rice nutrient solution to each culture pot, and set up 15 culture pots. Set up 3 culture pots as a single amino acid combination treatment group, 3 culture pots as a single small molecule substance combination treatment group, 9 culture pots as a combination treatment group of small molecule substances and amino acids, and 1 culture pot as a normal control group without treatment.

[0031] The formula for ordinary rice nutrient solution is a unique culture solution based on existing technology, as shown in Table 1 (nitrogen source not shown, i.e., nitrogen-free ordinary rice nutrient solution) (Reference: Yoshida S, Fomo DA, Cock JH, et al. Routine procedure for growing rice plants in culture solution. In: Laboratory manual for physiological studies of rice[J]. International Rice Research Institute, 61-66.). Through extensive research, the inventors discovered that a unique nitrogen-free ordinary rice nutrient solution can meet the needs of rice growth. The proportions in Table 1 meet the requirements of rice growth and represent a specific form of nitrogen-free ordinary rice nutrient solution.

[0032] Table 1: Nutrient Solution Formula for Common Rice

[0033] Amino acids, small molecule substances, and organic acids were prepared, with a stock solution concentration of 1 mol / L, for use in the preparation of the nutrient solution. The normal nutrient solution had a final nitrogen concentration of 2 mM, and the nutrient solution itself had a final inorganic nitrogen concentration of 1 mM. The remaining 1 mM was adjusted to achieve nitrogen balance by regulating the amino acid concentration. The small molecule substances included Br, melatonin, GABA, salicylic acid, and vitamin C. The specific details of the four groups in hydroponics (normal nutrient solution control group, single small molecule substance treatment group, single amino acid combination treatment group, and combined amino acid and small molecule substance treatment group) are as follows: Table 2: Hydroponic Treatment Formulas and Concentrations

[0034] After all treatments of "Guihong No. 1" rice reached the tillering stage, the plant height, fresh weight, root length, dry weight, and number of tillers were recorded for each treatment. One seedling from each treatment, with a plant height and number of tillers close to the average, was selected and laid out evenly in a row on a black cloth. The plant phenotype, fresh weight, dry weight, plant height, root length, and number of tillers of "Guihong No. 1" under each treatment condition are statistically analyzed as follows: Figure 1 , 2 As shown in Figure 3.

[0035] Depend on Figure 1 , Figure 2 , Figure 3The results show that, except for GH3 (normal nutrient solution + 0.1 μM BMR + 1 mM Vitamin C + 0.5 mM GABA + 1 μM Melatonin + 15 μM Salicylic Acid), GH7 (nutrient solution + 0.15 mM Arginine + 0.1 mM Alanine + 0.1 mM Phenylalanine + 0.1 mM Threonine + 0.1 mM Proline + 0.5 mM GABA + 15 μM Salicylic Acid + 1 μM Melatonin + 0.1 μM BMR), GH12 (nutrient solution + 0.15 mM Asparagine + 0.1 mM Alanine + 0.1 mM Methionine + 0.15 mM Tryptophan + 0.2 mM Serine + 0.5 mM GABA + 15 μM Salicylic Acid + 1 μM Melatonin + 1... Besides the four treatments of GH14 (nutrient solution + 0.2mM Vitamin C), 0.2mM glutamine + 0.2mM aspartic acid + 0.2mM tyrosine + 0.1mM cysteine ​​+ 0.1mM glycine + 0.5mM GABA + 15μM salicylic acid + 1μM melatonin + 1 mM Vitamin C + 0.1μM Br), adding amino acid combinations, small molecule combinations, or a combination of amino acid combinations and small molecule substances to the rice nutrient solution can all promote the growth of the rice variety "Guihong No. 1" to a certain extent. Specifically, in the small molecule combination treatment GH1, the addition of 0.5mM GABA, 15μM salicylic acid, 1μM melatonin, and 0.1μM Br to the rice nutrient solution significantly increased the plant height, root length, biomass (fresh weight), nitrogen content, chlorophyll content, single plant dry weight, and tiller number of "Guihong No. 1". Figure 1 This is the optimal processing method.

[0036] Example 2: Effects of different treatments on the percentage of total nitrogen content in 'Guihong No. 1' rice The rice used in this example was derived from the aforementioned culture materials. Nitrogen is the mineral element required in the largest quantity by plants and is also known as the "element of life." When nitrogen is sufficient, plants can synthesize more protein, promote cell division and enlargement, increase leaf area more rapidly, and enhance photosynthesis. Severe nitrogen deficiency hinders organic matter synthesis, resulting in stunted plants, yellowing leaves (especially older leaves), and therefore, nitrogen content in plants can be used as a physiological indicator of plant growth and development. The method for measuring nitrogen content in rice plants was based on the literature (Nanjing Agricultural College, ed. Soil Agrochemical Analysis. Beijing: Agricultural Press, 1980. 193-197).

[0037] Rice plant sampling: From the above organic nitrogen treatment group and inorganic nitrogen treatment group, the treatments that significantly promoted and inhibited the growth and development of "Guihong No. 1" were selected. A total of 6 treatments were added, including the control. Three rice plants were taken from each treatment and dried in an 80℃ oven overnight. After that, the dried plants were taken out and separated into leaves and stems. The samples were then pulverized into powder using a pulverizer for later use.

[0038] Determination of nitrogen content in plants: I. Digestion: 1. Weigh 0.5 g of the sample (dry sample) using a 0.01 g balance and place it in a digestion tube.

[0039] 2. Weigh 0.5 g of copper sulfate pentahydrate and 4.5 g of potassium sulfate using a 1 / 1000 balance and place them in a digestive tube.

[0040] 3. Accurately pipette 8 ml of concentrated sulfuric acid into a digestive tube.

[0041] 4. Turn on the instrument and begin digestion. First, digest at 280°C for about 20 minutes, then at 350°C for about 20 minutes, and finally at 450°C. Once the liquid in the digestion tube turns emerald green, continue digesting for another 30-40 minutes until digestion is complete.

[0042] 5. Allow to cool to room temperature before use.

[0043] II. Distillation and Titration: The digested sample solution should be diluted to 100 ml with distilled water. Pipette 5 ml of the test solution into the long glass tube of the nitrogen analyzer. Pipette 5 ml of boric acid indicator solution into a wide-mouthed Erlenmeyer flask. Distill for 3 minutes, then remove the flask. Titrate with a semi-micro burette, the titration changing from green to white to pink. Calculate the nitrogen content in the plant using the following formula.

[0044] Total nitrogen in plants (%) = Equivalent concentration of H2SO4 standard solution × (Volume of H2SO4 standard solution consumed during sample titration - Volume of H2SO4 standard solution in blank test) × Digestion factor × 0.014 × 100 / Sample weight.

[0045] In the formula: the fractional factor, following the above method, is 20, because 5 ml was drawn from 100 mL, and the sample weight is 0.5 g. Finally, the average value of the nitrogen content of the plants measured in the three replicate experiments for each treatment is calculated.

[0046] The nitrogen content data of plants measured for each treatment sample were statistically plotted, and the results are as follows: Figure 4 As shown in the figure, the above results again demonstrate that adding 0.5 mM GABA, 15 μM salicylic acid, 1 μM melatonin, and 0.1 μM Br to the rice nutrient solution can promote the growth and development of "Guihong No. 1". Figure 4 This improves the problem of poor growth and development in ordinary nutrient solutions.

[0047] Example 3: Effects of exogenous application of amino acids and small molecules on chlorophyll content in leaves of “Guihong No. 1”.

[0048] The rice materials used in this example were all derived from the aforementioned culture materials. The chlorophyll content of rice leaves is correlated with the photosynthetic rate and crop growth rate. In scientific research, chlorophyll content is often measured to characterize the growth status of rice, and in production, leaf color changes are often used as an important indicator for seedling diagnosis and the implementation of fertilization and irrigation measures. The method for measuring the chlorophyll content in rice leaves was based on the literature (Nurkamer Murat, Yang Yajie, Parhati Abdukerim, et al. Comparison of methods for determining chlorophyll content in wheat [J]. Jiangsu Agricultural Sciences, 2021, 49(09): 156-159).

[0049] Rice leaf sampling: Three rice seedlings (CK as control) were selected from the above treatment groups. The flag leaf portion was taken, and the leaf fragments (excluding veins) were chopped and mixed thoroughly. 0.2-0.3g of leaf fragments were weighed and placed in a mortar. A small amount of quartz sand, calcium carbonate powder, and 2-3ml of 95% ethanol were added, and the mixture was ground into a homogenate. Then, 10ml of 95% ethanol was added, and grinding continued until the tissue turned white. All residue was washed into a centrifuge tube with the extraction solvent, centrifuged, and the supernatant was taken and diluted to 25ml with 95% ethanol. The chloroplast pigment extract was further poured into a cuvette with a 1cm optical path. Using 95% ethanol as a blank, the absorbance was measured at wavelengths of 665nm, 649nm, and 470nm.

[0050] The calculation results are as follows: ①Ca = 13.95 * A665 - 6.88 * A649 ②Cb=24.96*A649-7.32*A665 ③CT=Ca+Cb ④ Chlorophyll content (mg / g) = (CT*VT) / V*M*1000 In the formula: ①Ca-chlorophyll a (mg / L); ②Cb-chlorophyll b (mg / L); ③Ct-chlorophyll content (mg / L); ④Vt - Total volume of extract (ml) = 25; ⑤V - Measured liquid volume (ml) = 200μ; ⑥m - Fresh weight of the sample.

[0051] Finally, the total chlorophyll content measured in the three replicate experiments for each treatment was averaged.

[0052] The measured chlorophyll content was statistically plotted, and the results are as follows: Figure 5 As shown. Based on the rice nutrient solution, using rice with added final concentrations of 0.5 mM GABA, 15 μM salicylic acid, 1 μM melatonin, and 0.1 μM Br, the total chlorophyll content of "Guihong No. 1" was ( Figure 5A) Chlorophyll a content ( Figure 5 B), Chlorophyll b ( Figure 5 The content of C) was increased compared to the control, with the total chlorophyll content significantly increased. Figure 5 A). The chlorophyll content in leaves is an important indicator of plant nutritional status. A high total chlorophyll content indicates a stronger photosynthetic potential, enabling the synthesis of more nutrients needed for plant growth and development. This further confirms that changing the nutrient solution formula can significantly improve the growth and development of "Guihong No. 1" and solve the problem of its poor growth and development in ordinary nutrient solutions, which makes it difficult to carry out factory-scale seedling cultivation. Against the backdrop of a gradual shortage of rural labor, this will accelerate the process of large-scale and intensive planting and management of "Guihong No. 1".

[0053] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention, but it should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention.

Claims

1. A nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1", characterized in that, The nutrient solution contains one of the following three amino acids at a final concentration: 0.1-0.5 mM arginine + 0.09-0.4 mM alanine + 0.08-0.3 mM phenylalanine + 0.1-0.5 mM threonine + 0.09-0.6 mM proline; 0.1-0.6 mM asparagine + 0.05-0.5 mM alanine + 0.05-0.5 mM methionine + 0.05-0.5 mM tryptophan + 0.1-0.6 mM serine; or 0.08-0.5 mM glutamine + 0.1-0.6 mM aspartic acid + 0.1-0.6 mM tyrosine + 0.05-0.5 mM cysteine ​​+ 0.1-0.5 mM glycine.

2. The nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" according to claim 1, characterized in that, It also contains 0.1~0.6μM Br, 1~6mM Vitamin C, 0.3~0.9mM GABA, 0.5~5μM melatonin, and 10~20μM salicylic acid.

3. The nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" according to claim 1, characterized in that, Also contains NaH2PO4·2H2O 63.000 mg / L, K2SO4 111.625 mg / L, CaCl2 39.55 mg / L, MgSO4·7H2O506 .250 mg / L, MnCl2·4H2O 1.761 mg / L, Na2MoO4·2H2O 0.127 mg / L, H3BO4 1.168 mg / L, ZnSO4·7H2O 0.044 mg / L, CuSO4·5H2O 0.039 mg / L, EDTA-Na2 15.000 mg / L, FeSO4·7H2O11.140 mg / L.

4. The nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" according to claim 1, characterized in that, The final nitrogen concentration in the nutrient solution is 1 mM.

5. The nutrient solution for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" according to claim 1, characterized in that, The Guizhou specialty indica rice variety "Guihong No. 1" is a representative red indica rice variety in Guizhou. Its growth period is 151 days, and it belongs to the medium-late maturing type. The seeds are long, with red seed coats, very few short awns, and colorless awn tips.

6. The application of the nutrient solution described in claim 1 for cultivating the Guizhou specialty indica rice variety "Guihong No. 1" in the cultivation of the Guizhou specialty indica rice variety "Guihong No. 1".

7. The application according to claim 6, characterized in that, The application mentioned in the cultivation of the Guizhou specialty indica rice variety "Guihong No. 1" is to improve the biomass, plant height, tiller number, nitrogen content, and chlorophyll content of "Guihong No. 1".

8. A method for cultivating the Guizhou specialty indica rice variety "Guihong No. 1", characterized in that, Rice seedlings at the three-leaf stage were cultured using the nutrient solution described in claim 1, wherein the rice seedling variety is "Guihong No. 1".

9. The method according to claim 8, characterized in that, Rice seedlings at the three-leaf stage are obtained by the following method: rice seeds are hydroponically cultured until the first incomplete leaf appears; the water is replaced with ordinary rice nutrient solution, and the seedlings are cultured until the tillering stage to obtain rice seedlings at the tillering stage.

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