A growth regulator for improving the germination rate of rice seeds and a preparation method thereof

Abstract

The application discloses a growth regulator for improving the germination rate of rice seeds and a preparation method thereof, and belongs to the technical field of plant growth regulators.The growth regulator comprises the following components in parts by weight: 3-5 parts of organic acid, 8-12 parts of pomegranate peel extract, 5-8 parts of PEG-4000, 3-5 parts of trehalose, 0.5-1 part of calcium pyrrolidone carboxylate, 0.01-0.05 parts of zinc sulfate, 0.1-0.3 parts of taurine and 0.05-0.1 parts of L-ascorbic acid; the organic acid is composed of malic acid and citric acid at a weight ratio of (1.2-1.5):1.The growth regulator for improving the germination rate of direct seeding rice seeds has a multi-component synergistic effect, can significantly enhance the energy metabolism and antioxidant capacity of the seeds, can significantly improve the germination rate, germination potential and germination index of the rice seeds under different temperature conditions, and promotes the growth of seedlings, and thus breaks through the bottleneck of the direct seeding technology of rice.

Description

Technical Field

[0001] This invention belongs to the field of plant growth regulator technology, specifically relating to a growth regulator for improving the germination rate of rice seeds and its preparation method. Background Technology

[0002] With changes in the rural labor force structure, limitations in arable land area, and structural adjustments in agriculture, rice production is accelerating its transformation towards large-scale, industrialized, and modernized operations, placing higher demands on planting efficiency and seed quality. However, traditional rice cultivation primarily relies on seedling transplanting, which involves complex processes such as seed drying, selection, soaking, germination, and hardening off, before transplanting via manual or mechanical planting. This model suffers from problems such as long cycles, high labor intensity, and high labor costs (accounting for 40%-60% of production costs). Furthermore, mechanical transplanting requires a high degree of field flatness, while manual transplanting easily damages the root system, leading to a prolonged seedling establishment period (approximately 5-7 days) and a delayed growth period. Additionally, pesticide soaking treatments can potentially cause environmental pollution.

[0003] Against this backdrop, direct seeding technology for rice has become an inevitable choice for achieving simplified and large-scale planting due to its advantages such as eliminating the seedling raising and transplanting stages, simplifying the process, and shortening the growth period (by 5-7 days). However, the promotion of direct seeding technology faces three core challenges: First, low seed germination rates lead to uneven emergence, requiring increased seeding density, resulting in higher production costs and overcrowding. Second, direct-seeded rice seeds are susceptible to adverse stresses such as low temperatures, drought, or waterlogging, leading to reduced germination rates. Third, seedlings are weak and prone to lodging, making it difficult to meet the demands of modern production for yield and quality. Currently, rice sowing often suffers from reduced seed vigor, low seedling rates, and uneven emergence due to factors such as uneven land and imperfect seed storage technology, further highlighting the urgent need for high-quality seeds.

[0004] Seed pretreatment is a core step in improving the field performance of direct-seeded rice, including techniques such as seed soaking, seed initiation, coating, and pelleting. Seed soaking, by immersing seeds in a specific solution, promotes respiratory metabolism recovery, provides energy for hypocotyl growth, and simultaneously kills seed-borne pests and diseases. Biostimulants and other components also activate antioxidant enzyme systems, accelerate free radical scavenging, and protect cell membrane structures, thereby simultaneously improving germination rate, emergence speed, and uniformity. However, existing technologies suffer from low germination efficiency, insufficient stress resistance, and complex processes, making it difficult to meet the requirements of modern production for high germination rates, high germination potential, high germination index, and high vigorous seeds. Therefore, developing a growth regulator that can simultaneously improve rice germination rate, seedling rate, and seedling quality, and by optimizing the seed soaking process to enhance seed stress resistance and metabolic activity, is of significant practical importance for overcoming the bottlenecks in direct-seeding technology and promoting the efficient and mechanized transformation of rice production. Summary of the Invention

[0005] The purpose of this invention is to provide a growth regulator that improves the germination rate of rice seeds, so as to solve the problems of low germination rate and uneven seedling formation in direct-seeded rice.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0007] A growth regulator for improving the germination rate of rice seeds, comprising, by weight, the following components:

[0008] The ingredients are: 3-5 parts organic acid, 8-12 parts pomegranate peel extract, 5-8 parts PEG-4000, 3-5 parts trehalose, 0.5-1 part calcium pyrrolidone carboxylate, 0.01-0.05 parts zinc sulfate, 0.1-0.3 parts taurine, and 0.05-0.1 parts L-ascorbic acid; wherein the organic acid is composed of malic acid and citric acid in a weight ratio of (1.2-1.5):1.

[0009] Preferably, the preparation method of the pomegranate peel extract includes the following steps:

[0010] Step a: After drying the pomegranate peel, crush it into powder. Mix the pomegranate peel powder with water at a ratio of 1:(8-10) g / mL, and adjust the pH to 5.0-5.5 to obtain a mixture.

[0011] Step b: Inoculate the compound microbial agent into the mixture obtained in step a, and ferment for 5-7 days at a temperature of 25-35℃ and a humidity of 80-85% to obtain the fermentation broth;

[0012] In step c, the obtained fermentation broth is extracted with a mixed solution of ethyl acetate and ethanol. The lower layer of the extract is taken, the solvent is removed by rotary evaporation, and the rotary evaporation product is freeze-dried to obtain pomegranate peel extract.

[0013] Preferably, in step b, the amount of compound microbial agent inoculated is 10-12% of the volume of the mixed liquid; the compound microbial agent is composed of Trichoderma koningii agent and Trichoderma harzianum agent in a weight ratio of 3:(1-2).

[0014] Preferably, the *Trichoderma koningii* agent is prepared by the following method: *Trichoderma koningii* is thawed and activated, then inoculated onto a PDA slant culture medium and cultured at 28°C for 5-7 days to form spores. The spores are then scraped off with sterile physiological saline, and the mycelium is removed by filtration, resulting in a spore suspension with a concentration of 10. 6 -10 7 CFU / mL; transfer the spore suspension to liquid modified PDA medium at an inoculation rate of 5%, and culture at 25℃ and 150 rpm for 2-3 days with shaking to obtain mycelial suspension. Vacuum freeze-drying yields Trichoderma koningii agent.

[0015] Preferably, the Trichoderma syn. strain is numbered CGMCC No.3.6612, deposited on April 15, 2003, and purchased from the China General Microbiological Culture Collection Center.

[0016] Preferably, the liquid modified PDA culture medium is composed of: 4 g / L potato extract powder, 20 g / L glucose, 4 g / L KH2PO4, 0.5 g / L MgSO4·7H2O, 0.1 g / L yeast extract, pH 4.5-5.0, and autoclaved at 121℃ for 20 minutes.

[0017] Preferably, the effective viable count of Trichoderma harzianum agent is ≥5 billion / g.

[0018] Preferably, the volume ratio of ethyl acetate to ethanol in the ethyl acetate-ethanol mixed solution is 10:(1-2).

[0019] This invention also provides a method for preparing a growth regulator to improve the germination rate of rice seeds, specifically including the following steps:

[0020] Step 1: Mix malic acid and citric acid in a certain proportion to obtain organic acids;

[0021] Step 2: Prepare pomegranate peel extract;

[0022] Step 3: Mix organic acids, pomegranate peel extract, PEG-4000, trehalose, calcium pyrrolidone carboxylate, zinc sulfate, taurine, and L-ascorbic acid evenly to obtain the final product.

[0023] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0024] When using the growth regulator of the present invention, the seed soaking solution is prepared at a ratio of 1g:500mL, and 10g can treat 3-5kg of dry seeds.

[0025] The present invention has the following beneficial effects:

[0026] 1. The two strains screened in this invention ferment pomegranate peel and then extract the extract, which is rich in fulvic acid, small molecule phenolic acids (tannic acid, gallic acid, etc.), flavonoids, polysaccharides, amino acids, and other active ingredients. The abundant fulvic acid contains numerous phenolic hydroxyl and quinone groups, which can regulate endogenous hormone balance and directly break seed dormancy. Its synergistic effect with small molecule organic acids composed of appropriate amounts of citric acid and malic acid allows for rapid absorption by seeds, activating mitochondrial respiratory chain enzyme activity, accelerating ATP synthesis, and providing energy for germination. Furthermore, some tannic acid in the pomegranate extract chelates with zinc ions in zinc sulfate to form metal complexes that promote seed germination, thereby promoting rice seed germination and growth, increasing seed germination rate, active ingredients, and antioxidant properties.

[0027] 2. The active ingredients in the pomegranate peel extract of this invention also have significant antibacterial activity, effectively inhibiting the growth of pathogenic microorganisms on the soil and seed surface during rice soaking or germination, reducing seed rot; at the same time, it can also scavenge reactive oxygen free radicals generated during seed germination, protecting cell membranes and organelles (such as mitochondria) from oxidative damage. The various active substances produced by fermentation constitute a "biostimulant complex," which significantly breaks through the seed germination threshold through multi-target effects (hormonal regulation, energy metabolism, and stress protection).

[0028] 3. The multi-component synergistic effect of this invention significantly improves the germination rate and germination potential of rice, promotes the seedling establishment rate and seedling growth (increases rice plant height), thereby enhancing the quality of seedlings and ensuring uniform and robust seedlings of direct-seeded rice. Attached Figure Description

[0029] Figure 1 This invention relates to the SOD enzyme activity of rice in different treatment groups during germination experiments under low-temperature conditions.

[0030] Figure 2 This invention relates to the GAD enzyme activity of rice in different treatment groups during germination under low temperature conditions.

[0031] Figure 3 This invention relates to the germination test of rice under low temperature conditions, and the FAE enzyme activity of different treatment groups.

[0032] Figure 4 The PAL enzyme activity of rice in different treatment groups was measured in a germination test under low temperature conditions according to this invention.

[0033] Figure 5 This is a comparison of the morphology of rice in Example 3, the blank control, and Comparative Examples 1-5 after germination 3 days under the 28℃ constant temperature germination test of this invention. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to specific embodiments, but is not limited thereto. The Trichoderma harzianum agent used in the embodiments of the present invention has an effective viable count of 5 billion / g and was purchased from Shandong Wanyang Biotechnology Co., Ltd.

[0035] Example 1

[0036] A growth regulator for improving the germination rate of rice seeds, comprising, by weight, the following components: 3 parts organic acid, 8 parts pomegranate peel extract, 5 parts PEG-4000, 3 parts trehalose, 0.5 parts calcium pyrrolidone carboxylate, 0.01 parts zinc sulfate, 0.1 parts taurine, and 0.05 parts L-ascorbic acid; wherein the organic acid is composed of malic acid and citric acid in a weight ratio of 1.2:1.

[0037] The preparation method of the pomegranate peel extract includes the following steps:

[0038] Step a: After drying the pomegranate peel, crush it into powder. Mix the pomegranate peel powder with water at a ratio of 1:8 g / mL, and adjust the pH to 5.0 to obtain a mixture.

[0039] Step b: Inoculate the compound microbial agent into the mixture obtained in step a, and ferment for 5 days at a temperature of 25°C and a humidity of 85% to obtain a fermentation broth; the inoculation amount of the compound microbial agent is 10% of the volume of the mixture; the compound microbial agent is composed of Trichoderma koningii and Trichoderma harzianum in a weight ratio of 3:1.

[0040] In step c, the obtained fermentation broth is extracted with a mixed solution of ethyl acetate and ethanol. The lower layer of the extract is taken, the solvent is removed by rotary evaporation, and the rotary evaporation product is freeze-dried to obtain pomegranate peel extract. The volume ratio of ethyl acetate to ethanol in the mixed solution of ethyl acetate and ethanol is 10:1.

[0041] The *Trichoderma koningii* fungal agent is prepared by the following method: *Trichoderma koningii* is thawed and activated, then inoculated onto PDA slant culture medium and cultured at 28℃ for 5-7 days to form spores. The spores are then scraped off with sterile physiological saline, and the mycelium is removed by filtration, resulting in a spore suspension with a concentration of 10%. 6 -10 7 CFU / mL; the spore suspension was transferred to modified liquid PDA medium at an inoculum of 5%, and cultured at 25℃ and 150 rpm for 2-3 days with shaking to obtain mycelial suspension, which was then freeze-dried under vacuum to obtain Trichoderma koningii agent; the Trichoderma koningii strain was numbered CGMCC No.3.6612, deposited on April 15, 2003, and purchased from China General Microbiological Culture Collection Center.

[0042] The liquid modified PDA medium consists of: 4 g / L potato extract, 20 g / L glucose, 4 g / L KH2PO4, 0.5 g / L MgSO4·7H2O, 0.1 g / L yeast extract, pH 4.5-5.0, and autoclaved at 121℃ for 20 minutes.

[0043] The preparation method of the above-mentioned growth regulator for improving rice seed germination rate specifically includes the following steps:

[0044] Step 1: Mix malic acid and citric acid in a certain proportion to obtain organic acids;

[0045] Step 2: Prepare pomegranate peel extract;

[0046] Step 3: Mix organic acids, pomegranate peel extract, PEG-4000, trehalose, calcium pyrrolidone carboxylate, zinc sulfate, taurine, and L-ascorbic acid evenly to obtain the final product.

[0047] Example 2

[0048] A growth regulator for improving the germination rate of rice seeds, comprising, by weight, the following components: 5 parts organic acid, 12 parts pomegranate peel extract, 8 parts PEG-4000, 5 parts trehalose, 1 part calcium pyrrolidone carboxylate, 0.05 parts zinc sulfate, 0.3 parts taurine, and 0.1 parts L-ascorbic acid; wherein the organic acid is composed of malic acid and citric acid in a mass ratio of 1.5:1.

[0049] The preparation method of the pomegranate peel extract includes the following steps:

[0050] Step a: After drying the pomegranate peel, crush it into powder. Mix the pomegranate peel powder with water at a ratio of 1:10 g / mL, and adjust the pH to 5.5 to obtain a mixture.

[0051] Step b: Inoculate the compound microbial agent into the mixture obtained in step a, and ferment for 5 days at a temperature of 35°C and a humidity of 80% to obtain a fermentation broth; the inoculation amount of the compound microbial agent is 12% of the volume of the mixture; the compound microbial agent is composed of Trichoderma koningii and Trichoderma harzianum in a weight ratio of 3:2.

[0052] In step c, the obtained fermentation broth is extracted with a mixed solution of ethyl acetate and ethanol. The lower layer of the extract is taken, the solvent is removed by rotary evaporation, and the rotary evaporation product is freeze-dried to obtain pomegranate peel extract. The volume ratio of ethyl acetate to ethanol in the mixed solution of ethyl acetate and ethanol is 10:2.

[0053] The *Trichoderma koningii* fungal agent is prepared by the following method: *Trichoderma koningii* is thawed and activated, then inoculated onto PDA slant culture medium and cultured at 28℃ for 5-7 days to form spores. The spores are then scraped off with sterile physiological saline, and the mycelium is removed by filtration, resulting in a spore suspension with a concentration of 10%. 6 -10 7 CFU / mL; the spore suspension was transferred to modified liquid PDA medium at an inoculum of 5%, and cultured at 25℃ and 150 rpm for 2-3 days with shaking to obtain mycelial suspension, which was then freeze-dried under vacuum to obtain Trichoderma koningii agent; the Trichoderma koningii strain was numbered CGMCC No.3.6612, deposited on April 15, 2003, and purchased from China General Microbiological Culture Collection Center.

[0054] The liquid modified PDA medium consists of: 4 g / L potato extract, 20 g / L glucose, 4 g / L KH2PO4, 0.5 g / L MgSO4·7H2O, 0.1 g / L yeast extract, pH 4.5-5.0, and autoclaved at 121℃ for 20 minutes.

[0055] The preparation method of the above-mentioned growth regulator for improving rice seed germination rate specifically includes the following steps:

[0056] Step 1: Mix malic acid and citric acid in a certain proportion to obtain organic acids;

[0057] Step 2: Prepare pomegranate peel extract;

[0058] Step 3: Mix organic acids, pomegranate peel extract, PEG-4000, trehalose, calcium pyrrolidone carboxylate, zinc sulfate, taurine, and L-ascorbic acid evenly to obtain the final product.

[0059] Example 3

[0060] A growth regulator for improving the germination rate of rice seeds, comprising, by weight, the following components: 4 parts organic acid, 10 parts pomegranate peel extract, 7 parts PEG-4000, 4 parts trehalose, 0.8 parts calcium pyrrolidone carboxylate, 0.03 parts zinc sulfate, 0.2 parts taurine, and 0.08 parts L-ascorbic acid; wherein the organic acid is composed of malic acid and citric acid in a mass ratio of 1.4:1.

[0061] The preparation method of the pomegranate peel extract includes the following steps:

[0062] Step a: After drying the pomegranate peel, crush it into powder. Mix the pomegranate peel powder with water at a ratio of 1:9 g / mL, and adjust the pH to 5.2 to obtain a mixture.

[0063] Step b: Inoculate the compound microbial agent into the mixture obtained in step a, and ferment for 6 days at a temperature of 30°C and a humidity of 85% to obtain a fermentation broth; the inoculation amount of the compound microbial agent is 11% of the volume of the mixture; the compound microbial agent is composed of Trichoderma koningii and Trichoderma harzianum in a weight ratio of 3:1.

[0064] In step c, the obtained fermentation broth is extracted with a mixed solution of ethyl acetate and ethanol. The lower layer of the extract is taken, the solvent is removed by rotary evaporation, and the rotary evaporation product is freeze-dried to obtain pomegranate peel extract. The volume ratio of ethyl acetate to ethanol in the mixed solution of ethyl acetate and ethanol is 10:1.

[0065] The *Trichoderma koningii* fungal agent is prepared by the following method: *Trichoderma koningii* is thawed and activated, then inoculated onto PDA slant culture medium and cultured at 28℃ for 5-7 days to form spores. The spores are then scraped off with sterile physiological saline, and the mycelium is removed by filtration, resulting in a spore suspension with a concentration of 10%. 6 -10 7CFU / mL; the spore suspension was transferred to modified liquid PDA medium at an inoculum of 5%, and cultured at 25℃ and 150 rpm for 2-3 days with shaking to obtain mycelial suspension, which was then freeze-dried under vacuum to obtain Trichoderma koningii agent; the Trichoderma koningii strain was numbered CGMCC No.3.6612, deposited on April 15, 2003, and purchased from China General Microbiological Culture Collection Center.

[0066] The liquid modified PDA medium consists of: 4 g / L potato extract, 20 g / L glucose, 4 g / L KH2PO4, 0.5 g / L MgSO4·7H2O, 0.1 g / L yeast extract, pH 4.5-5.0, and autoclaved at 121℃ for 20 minutes.

[0067] The preparation method of the above-mentioned growth regulator for improving rice seed germination rate specifically includes the following steps:

[0068] Step 1: Mix malic acid and citric acid in a certain proportion to obtain organic acids;

[0069] Step 2: Prepare pomegranate peel extract;

[0070] Step 3: Mix organic acids, pomegranate peel extract, PEG-4000, trehalose, calcium pyrrolidone carboxylate, zinc sulfate, taurine, and L-ascorbic acid evenly to obtain the final product.

[0071] Comparative Example 1

[0072] A growth regulator for improving the germination rate of rice seeds has the same raw material composition and preparation method as in Example 3. The only difference is that the pomegranate peel extract is prepared by the traditional water extraction method. Specifically, the pomegranate peel is dried and pulverized. The pomegranate peel powder is mixed with water at a ratio of 1:9 g / mL, heated to 90°C, extracted for 6 hours, and the extract is concentrated and freeze-dried to obtain the final product.

[0073] Comparative Example 2

[0074] A growth regulator for improving the germination rate of rice seeds has the same raw material composition and preparation method as in Example 3, except that the organic acid is composed of malic acid and citric acid in a weight ratio of 1.1:1.

[0075] Comparative Example 3

[0076] A growth regulator for improving the germination rate of rice seeds has the same raw material composition and preparation method as in Example 3, except that the organic acid is composed of malic acid and citric acid in a weight ratio of 1.6:1.

[0077] Comparative Example 4

[0078] A growth regulator to improve the germination rate of rice seeds has the same raw material composition and preparation method as in Example 3. The only difference is that the compound microbial agent in step b of the pomegranate peel extract preparation process is only Trichoderma tsunemae.

[0079] Comparative Example 5

[0080] A growth regulator to improve the germination rate of rice seeds has the same raw material composition and preparation method as in Example 3. The only difference is that the compound microbial agent in step b of the pomegranate peel extract preparation process is only Trichoderma harzianum agent.

[0081] Performance testing

[0082] To verify the effect of the plant growth regulator of the present invention on the germination rate of rice seeds, comparative experiments were conducted on the plant growth regulators prepared in Examples 1-3 and Comparative Examples 1-5.

[0083] Experimental Methods: Nine treatments were set up: Examples 1-3, Comparative Examples 1-5, and a blank control. Each treatment involved soaking seeds in the same dose of different growth regulators before germination rate testing. The blank control group was treated with an equal volume of water. Each treatment was replicated three times. The tested rice variety was Shengdao 25, stored at room temperature for 6 months. A soaking solution was prepared at 1g regulator: 500mL water, and the seeds were soaked at 25℃ for 24 hours. The soaked rice seeds were placed in standard germination dishes and then placed in an artificial climate chamber with 60% relative humidity at 28℃ for constant temperature cultivation. Forty rice seeds were placed in each treatment. Each treatment was given 12 hours of light. The number of germinated seeds in each treatment was counted daily after sowing, and the germination rate, germination potential, germination index, and number of germinated seeds (radicle ≥2mm was the germination standard) were calculated. The calculation method is as follows:

[0084] Germination potential (%) = Total number of seeds germinated within 3 days / Number of seeds tested × 100%;

[0085] Germination rate (%) = (Total number of seeds germinated within 7 days / Number of seeds tested) × 100%;

[0086] Germination index = ∑Gi / Di (Gi is the number of germinated plants on day i, and Di is the number of germinated plants on day i). The results are shown in Table 1.

[0087] Table 1. Germination rate test results at 28℃ constant temperature incubation

[0088]

[0089] Note: Data are mean ± standard deviation (n=3).

[0090] As shown in Table 1, the germination rates of Examples 1-3 all exceeded 98%, the germination potential exceeded 92%, and the germination index was between 31.2 and 33.5, indicating that the growth regulator of the present invention can significantly improve the germination rate and germination potential of rice seeds. In contrast, the germination rates, germination potentials, and germination indices of Comparative Examples 1-5 were significantly lower than those of the Example groups, indicating that changing the formulation or preparation method of the growth regulator would reduce its germination-promoting effect. The blank control group, which did not use the growth regulator, had a germination rate of only 83.5%, a germination potential of 70.6%, and a germination index of 21.3, far lower than that of the Example groups, further demonstrating the effectiveness of the growth regulator.

[0091] On the 10th day after sowing, 10 rice seedlings were selected from each treatment using a five-point sampling method. The fresh weight of the seedlings, seedling height, root length, and root fresh weight were measured using vernier calipers and an electronic balance. The specific results are shown in Table 2.

[0092] Table 2 Effects of different treatment groups on rice seedling growth

[0093]

[0094] As shown in Table 2 above, the rice seedlings treated in Examples 1-3 were superior to the comparative group and the blank control group in terms of seedling fresh weight, seedling height, root length, and root fresh weight. This indicates that the growth regulator of the present invention can not only improve the germination rate but also promote seedling growth. However, the growth indicators of the rice seedlings treated in Comparative Examples 1-5 were all lower than those in the Example group, indicating that changes in the formulation or preparation method can affect the promoting effect of the growth regulator on seedling growth.

[0095] This invention also verified the effect of the growth regulator of this invention on the germination rate of rice seeds under low-temperature conditions. The experimental method was basically the same as the above-mentioned experimental method, the only difference being that constant temperature incubation was carried out at 15℃. Germination potential (%) = total number of seeds germinated within 7 days / number of tested seeds × 100%;

[0096] Germination rate (%) = Total number of seeds germinated within 10 days / Number of seeds tested × 100%;

[0097] Germination index = ∑Gt / Dt (Gt is the number of germinated plants on day t, and Dt is the number of germinated plants on day t).

[0098] Table 3. Effects of different treatment groups on rice germination rate under low temperature (15℃) conditions.

[0099]

[0100] As can be seen from Table 3 above, the germination rate of Examples 1-3 remained above 90% under low-temperature conditions, the germination potential exceeded 82%, and the germination index was between 22.5 and 26.1, indicating that the growth regulator of the present invention can effectively improve the germination rate and germination potential of rice seeds under low-temperature conditions. In contrast, the germination rate, germination potential, and germination index of Comparative Examples 1-5 were significantly lower than those of the Example group under low-temperature conditions, indicating that changing the formulation or preparation method would reduce the effectiveness of the growth regulator under low-temperature conditions.

[0101] After germination for 5 days, 10 rice grains from each treatment group were randomly selected and dried at 45℃ to constant weight. The dried grains were then pulverized through a 0.35mm sieve to obtain rice powder, which was stored at 4℃ for the determination of superoxide dismutase (SOD), glutamate decarboxylase (GAD), ferulic acid esterase (FAE), and phenylalanine ammonia-lyase (PAL) activities. SOD was determined using the nitroblue tetrazolium (NBT) photochemical reduction method; GAD was determined using ultraviolet spectrophotometry (GABA absorbance at 340 nm); FAE was determined using methyl ferulic acid hydrolysis-HPLC; and PAL was determined using the L-phenylalanine deamination reaction (OD290). Detailed results are shown below. Figures 1-4 As shown.

[0102] Depend on Figures 1-4It was found that the SOD, GAD, FAE, and PAL enzyme activities of rice seedlings in the treatment groups of Examples 1-3 were significantly higher than those in Comparative Examples 1-5 and the blank control group. SOD (superoxide dismutase) is a key enzyme in the antioxidant system, capable of scavenging superoxide anion free radicals and protecting cells from oxidative damage. The increased SOD activity in the Example groups indicates that the growth regulators alleviated the oxidative damage to rice seeds under low-temperature stress by enhancing antioxidant capacity. GAD (glutamate decarboxylase) catalyzes the production of γ-aminobutyric acid (GABA) from glutamate, which is an important osmotic regulator for plants to cope with stress. The increased GAD activity in the Example groups indicates that the growth regulators enhanced the resistance of rice to stresses (such as low temperature and drought) by promoting GABA synthesis. The lower GAD activity in the comparative groups was due to the lack of compound microbial agents, leading to reduced synthesis of biostimulants (such as fulvic acid and small molecule phenolic acids), which could not effectively induce GAD expression. FAE (feruloesterase) participates in cell wall degradation and the release of phenolic acids, and is closely related to seed germination and stress resistance. The increased FAE activity in the example group indicates that the growth regulator, through optimizing the preparation process of pomegranate peel extract, released more bound ferulic acid and other active ingredients, promoting cell wall loosening and germination-related gene expression. PAL (phenylalanine ammonia-lyase) is a key enzyme in the synthesis of phenolic acids, participating in lignin synthesis and disease resistance responses. The increased PAL activity in the example group suggests that the growth regulator, by adjusting the ratio of organic acids (malic acid / citric acid) and the fermentation of the compound microbial agent, may have activated the phenylpropane metabolic pathway, promoting the synthesis of phenolic acids (such as tannic acid and gallic acid). In Comparative Examples 2 and 3, the organic acid ratio deviated from the optimal range (1.2-1.5:1), which may have affected cell membrane permeability and enzyme activity, leading to a decrease in PAL expression.

[0103] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A growth regulator for improving the germination rate of rice seeds, characterized in that, By weight, it includes the following ingredients: The ingredients include 3-5 parts organic acid, 8-12 parts pomegranate peel extract, 5-8 parts PEG-4000, 3-5 parts trehalose, 0.5-1 part calcium pyrrolidone carboxylate, 0.01-0.05 parts zinc sulfate, 0.1-0.3 parts taurine, and 0.05-0.1 parts L-ascorbic acid; wherein the organic acid is composed of malic acid and citric acid in a weight ratio of (1.2-1.5):

1. The pomegranate peel extract was prepared using the following method: Step a: After drying the pomegranate peel, crush it into powder. Mix the pomegranate peel powder with water at a ratio of 1:(8-10) g / mL, and adjust the pH to 5.0-5.5 to obtain a mixture. Step b: Inoculate the compound microbial agent into the mixture obtained in step a, and ferment for 5-7 days at a temperature of 25-35℃ and a humidity of 80-85% to obtain the fermentation broth; Step c: The obtained fermentation broth is extracted with a mixed solution of ethyl acetate and ethanol. The lower layer of the extract is taken, the solvent is removed by rotary evaporation, and the rotary evaporation product is freeze-dried to obtain pomegranate peel extract. The volume ratio of ethyl acetate to ethanol in the mixed solution of ethyl acetate and ethanol is 10:(1-2). In step b, the amount of compound microbial agent inoculated is 10-12% of the volume of the mixed liquid; the compound microbial agent is composed of Trichoderma koningii agent and Trichoderma harzianum agent in a weight ratio of 3:(1-2); The Trichoderma syn. strain was numbered CGMCC No. 3.6612, deposited on April 15, 2003, and purchased from the China General Microbiological Culture Collection Center. The Trichoderma harzianum agent has an effective viable count of 5 billion / g and was purchased from Shandong Wanyang Biotechnology Co., Ltd.

2. The growth regulator for improving rice seed germination rate according to claim 1, characterized in that, The *Trichoderma koningii* fungal agent is prepared by the following method: *Trichoderma koningii* is thawed and activated, then inoculated onto PDA slant culture medium and cultured at 28℃ for 5-7 days to form spores. The spores are then scraped off with sterile physiological saline, and the mycelium is removed by filtration, resulting in a spore suspension with a concentration of 10%. 6 -10 7 CFU / mL; transfer the spore suspension to liquid modified PDA medium at an inoculation rate of 5%, and culture at 25℃ and 150 rpm for 2-3 days with shaking to obtain mycelial suspension. Vacuum freeze-drying yields Trichoderma konjac inoculum.

3. The growth regulator for improving rice seed germination rate according to claim 2, characterized in that, The composition of the liquid modified PDA medium is as follows: 4 g / L potato extract powder, 20 g / L glucose, 0.5 g / L KH2PO4, 0.5 g / L MgSO4·7H2O, 0.1 g / L yeast extract, pH 4.5-5.0, autoclaved at 121℃ for 20 minutes.

4. A method for preparing a growth regulator for improving rice seed germination rate according to any one of claims 1-3, characterized in that, It includes the following steps: Step 1: Mix malic acid and citric acid in a certain proportion to obtain organic acids; Step 2: Prepare pomegranate peel extract; Step 3: Mix organic acids, pomegranate peel extract, PEG-4000, trehalose, calcium pyrrolidone carboxylate, zinc sulfate, taurine, and L-ascorbic acid evenly to obtain the final product.

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