Combined modulator for alleviating long-term low-temperature stress to promote rice seed germination and application

Abstract

The present application relates to the field of agricultural planting technology, and specifically discloses a combined regulator for relieving long-term low-temperature stress and promoting rice seed germination and application, wherein the effective component of the combined regulator is composed of 5-10 mg / L gibberellin and 0.4-0.6% chitosan (CS). The present application adopts the method of combining non-hormone regulators with osmoregulation regulators to screen out the optimal priming agent: 10 mg / L gibberellin+0.5% chitosan combined regulator, which not only has a high germination rate (94.67%) in a low-temperature environment, but also has a high germination index (40.63), and the germination index is significantly greater than that of common regulators, and is especially suitable for use in areas where the duration of "cold spring" is long or the duration of low temperature in the sowing season is long.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting technology, and specifically relates to a combined regulator for alleviating long-term low-temperature stress and promoting rice seed germination and its application. Background Technology

[0002] Rice (Oryza sativa L.) is my country's most important food crop, but due to low economic benefits, the rice planting area has been declining. The phenomenon of switching from double-cropping rice to single-cropping rice, and even abandoning early rice fields, is widespread in Guangxi. The biggest cost in rice cultivation is seedling raising and transplanting. Whether by manual throwing, transplanting, or machine transplanting, the production cost of seedling raising and transplanting accounts for more than 30% of the total cost of rice production. Mechanized direct seeding of rice significantly reduces costs by eliminating the seedling raising, transportation, and transplanting processes, and also saves labor. In recent years, with the continuous expansion of rural land transfer and the national support for standardized farmland construction, the conversion of dry land to paddy fields and small-scale farmland to large-scale farmland has provided favorable conditions for mechanized precision direct seeding of rice, and mechanized direct seeding of rice has received widespread attention and adoption.

[0003] Currently, the most significant problem encountered in the promotion of direct-seeded rice is the low temperatures caused by late spring frosts and overcast skies with insufficient sunlight, which severely impacts the emergence quality of direct-seeded rice, making it difficult to achieve full seedling emergence upon sowing and directly affecting the yield. This problem can be solved by breeding suitable, low-temperature-tolerant varieties for direct seeding, but the breeding cycle is long and difficult to implement quickly. The simplest and most effective solution currently is to improve the seedling emergence rate through a combination of regulators. Our team previously applied for a patent, "A method for regulating the germination of early direct-seeded rice seeds under low-temperature stress" (202210237085.X), which uses seeds treated with GA3+SA to improve the germination and emergence rates of rice seeds under low-temperature stress, ensuring full seedling emergence upon sowing and promoting the rapid development of direct-seeded rice. However, the germination index of seeds treated with GA3+SA is not high, and the germination and emergence rates will also be affected in areas with harsh environments and prolonged late spring frosts. Our team has further optimized the formulation of combined regulators, combining hormone-based regulators with osmotic regulators to obtain regulators with high germination rates and germination indices. These regulators have significant advantages in areas with harsh environments and prolonged periods of late spring frost, providing technical support for the promotion of direct seeding of early rice and playing an important role in advancing mechanized direct seeding of rice. Summary of the Invention

[0004] The purpose of this invention is to provide a combined regulator for alleviating long-term low-temperature stress and promoting rice seed germination, and its application, thereby overcoming the shortcomings of existing direct-seeded rice in areas with harsh environments and long periods of "late spring cold," where rice seeds are easily affected by low-temperature stress, resulting in low germination rates and easy seed rot.

[0005] To achieve the above objectives, the present invention provides a combined regulator for alleviating long-term low-temperature stress and promoting rice seed germination. The effective components of the combined regulator are gibberellin and chitosan, wherein the seed soaking concentration of gibberellin is 5-10 mg / L and the seed soaking concentration of chitosan is 0.4-0.6%.

[0006] Gibberellin is a hormone-type initiator, and chitosan is an osmotic initiator. The combination of the two can activate plant resistance, improve various seed germination indicators, and reduce the adverse effects of abiotic stress on seed germination. Practice has shown that chitosan + gibberellin can resist low temperatures for extended periods, making it particularly suitable for use in areas with prolonged periods of late spring frost.

[0007] Preferably, the gibberellin soaking concentration is 10 mg / L, and the chitosan soaking concentration is 0.5%.

[0008] Another technical solution of this application:

[0009] A method for promoting rice seed germination using the above-mentioned combined regulators includes the following steps:

[0010] (1) Initiation treatment: Select plump, low-temperature resistant rice seeds, then soak them in the combined regulator and initiate treatment at 12-15℃ for 24 hours;

[0011] (2) Drying treatment: After initiation, rice seeds are put into mesh bags, rinsed with tap water, drained, and dried at a constant temperature of 25℃.

[0012] (3) Sowing: After drying, rice seeds can be sown directly or stored in a self-sealing bag at 4°C for later use.

[0013] Preferably, the process also includes step (4) germination: statistical analysis of the germination status of each combination, including germination rate, germination index and germination length, and scanning of the plants after germination.

[0014] Preferably, the low-temperature resistant rice seed is Huang Huazhan. The low-temperature resistant rice seed is first disinfected with 1% strong chlorine for 20 minutes; then rinsed clean with water, and then soaked in the combined regulator.

[0015] Preferably, in step (1), the mass ratio of the low-temperature resistant rice seeds to the volume ratio of the combined regulator is 1:4-6 (w / v).

[0016] Preferably, in step (1), the low-temperature resistant rice seeds are induced for 12 hours under dark conditions at 12°C, and then induced for 12 hours under light conditions at 15°C.

[0017] Preferably, in step (2), the rinsing time with tap water is 3 minutes; the drying operation is: placing it in a constant temperature drying oven at 25°C for 48 hours.

[0018] Preferably, in step (3), the dried rice seeds are sown into the paddy field by mechanical direct seeding.

[0019] Compared with existing technologies, the present invention has the following advantages:

[0020] Based on the combined regulators that can improve the germination rate of rice seeds under low temperature conditions screened in the early stage, this application uses a combination of hormone regulators and osmotic regulators to screen out the optimal initiator: 10 mg / L gibberellin + 0.5% chitosan combined regulator. It not only has a high germination rate (94.67%) in low temperature conditions, but also has a high germination index (40.63), which is significantly higher than that of ordinary regulators. It is especially suitable for use in areas where the "late spring cold" lasts for a long time or where the low temperature lasts for a long time during the sowing season. Attached Figure Description

[0021] Figure 1 This is a comparison chart of the growth of rice seeds 15 days after different combinations of growth regulators in Example 1. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0023] Example 1

[0024] (1) Test varieties: Based on previous experiments, Huanghuazhan, a rice variety that is relatively sensitive to low temperature conditions, was selected.

[0025] (2) Single combination regulator configuration: Based on the previous screening, the optimal hormone regulators were retained: 0.3 mg / L brassinolide (BR), 10 mg / L gibberellin (GA3), 15% polyethylene glycol (PEG6000) and the optimal osmotic regulator: 0.5% chitosan (CS). The four regulators were configured in pairs to treat the tested varieties, and the control was seed soaking in distilled water.

[0026] The screening method for the optimal hormone regulator can be found in the description of Example 1 of my patent CN202210237085.X. The germination conditions for rice seeds were: 12℃ for 12h in darkness, 15℃ for 12h in light (12000 lxs), repeated cyclically.

[0027] (3) Experimental Design

[0028] Plump rice seeds were selected and disinfected with 1% sodium chloride (NaClO) for 15-20 minutes. After rinsing with sterile water, the seeds were soaked in a combination of different concentrations of seed conditioner for 24 hours. After rinsing with sterile water, the seeds were placed in germination boxes for germination. Each box contained 100 seeds, with three replicates for each treatment, and water was used as a control. The germination boxes were then placed in an artificial climate chamber for germination under the following conditions: 12℃ for 12 hours in darkness, 15℃ for 12 hours under light (12000 lxs), repeated cyclically. Sterile water was added as needed during the experiment. Germination rate was recorded daily for 7 days, and the total germination rate and germination index were calculated to determine the optimal combination.

[0029] III. Test Results

[0030] Screening results of the optimal combination regulators: Compared with the control, among the four combination regulators, the germination rate and germination index of 10 mg / L gibberellin + 0.5% chitosan were higher than those of the control, by 16.9% and 32.5%, respectively.

[0031] Table 1. Statistics on seed germination rate and germination index under different treatments under low temperature stress.

[0032]

[0033] After germination, based on the weather patterns of early rice in Guangxi, the temperature was adjusted to 18℃ for 12 hours of darkness and 25℃ for 12 hours of light, allowing the seedlings to grow for 15 days. The seedling growth was then observed. Figure 1 ).

[0034] In other experiments, the germination rate of rice seeds treated with a combination of 10 mg / L gibberellin and 0.5% chitosan was not significantly different from that of seeds treated with GA3 and SA (only an increase of 0.67%). However, the germination index of the seeds treated with 10 mg / L gibberellin and 0.5% chitosan was 40.63, which was significantly higher than the germination index of 10.97 of the seeds treated with GA3 and SA. This indicates that 10 mg / L gibberellin and 0.5% chitosan has significant advantages in areas with harsh environments, late spring frosts, or prolonged periods of low temperatures during sowing.

[0035] From the perspective of initiation principles, osmotic initiation and hormone initiation are not the same. (1) Osmotic initiation technology uses solute as an initiator, places the seeds on filter paper moistened with solution or directly immerses them in solution, and adjusts the water absorption rate and amount of the seeds by controlling the water potential of the solution, thereby achieving the initiation effect. According to the different initiators, osmotic initiation can be divided into two categories: organic osmotic substances and inorganic osmotic substances. Chitosan belongs to organic osmotic substances. Chitosan is a natural high molecular weight polysaccharide, mainly derived from seafood processing waste. Soaking seeds in a chitosan solution of appropriate concentration can improve various seed germination indicators and reduce the adverse effects of abiotic stress on seed germination.

[0036] Hormone initiation is a method of seed priming by soaking seeds in a hormone solution of a certain concentration. Plant hormones are organic substances produced by the plant itself that can significantly regulate plant growth and development in small doses. Currently, commonly used plant hormones for seed priming can be divided into two categories: traditional plant hormones, such as gibberellins, abscisic acid, auxins, and cytokinins; and novel plant hormones, including brassinolide, salicylic acid, jasmonic acid derivatives, and polyamines.

[0037] In terms of germination effect, although the germination rates of chitosan + GA3 and salicylic acid + GA3 are basically the same, the germination index ((germination rate + germination speed) / 2) of chitosan + GA3 shows that chitosan + GA3 can withstand low temperature for a longer period of time.

[0038] Furthermore, experiments have shown that different crop varieties have different seed structures, resulting in varying germination rates even with the same regulator concentration. For the same crop variety, different concentrations of regulators will also produce different germination effects.

[0039] In summary, based on the combined regulators that can improve the germination rate of rice seeds under low temperature conditions screened in the previous stage, this application selected the optimal initiator by combining non-hormonal regulators and osmotic regulators: a combined regulator of 10 mg / L gibberellin + 0.5% chitosan. This regulator not only has a high germination rate (94.67%) in low temperature conditions, but also a high germination index (40.63), which is significantly higher than that of ordinary regulators. It is especially suitable for use in areas where the "late spring cold" lasts for a long time.

[0040] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0041] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A combined regulator for alleviating long-term low-temperature stress and promoting rice seed germination, characterized in that, The active ingredients of the combined regulator consist of gibberellin and chitosan, wherein the soaking concentration of gibberellin is 10 mg / L and the soaking concentration of chitosan is 0.5%.

2. A method for promoting rice seed germination using the combined regulator of claim 1, comprising the following steps: (1) Initiation treatment: Select plump, low-temperature resistant rice seeds, then soak them in the combined regulator and initiate treatment at 12-15℃ for 24 hours; (2) Drying treatment: After initiation, put the rice seeds into a mesh bag, rinse them with tap water, drain the water, and dry them at a constant temperature of 25°C. (3) Sowing: After drying, rice seeds can be sown directly or stored in a self-sealing bag at 4°C for later use.

3. The method according to claim 2, characterized in that, It also includes step (4) germination: statistical analysis of the germination status of each combination, including germination rate, germination index and germination length, and scanning of the plants after germination.

4. The method according to claim 2, characterized in that, In step (1), the low-temperature resistant rice seeds are Huang Huazhan. The low-temperature resistant rice seeds are first disinfected with 1% strong chlorine for 20 minutes; then rinsed with water and soaked in the combined regulator.

5. The method according to claim 2, characterized in that, In step (1), the mass ratio of the low-temperature resistant rice seeds to the volume ratio of the combined regulator is 1:4-6 (w / v).

6. The method according to claim 2, characterized in that, In step (1), the low-temperature resistant rice seeds are induced for 12 hours under dark conditions at 12°C, and then induced for 12 hours under light conditions at 15°C.

7. The method according to claim 2, characterized in that, In step (2), the rinsing time with tap water is 3 minutes; the drying operation is: place it in a constant temperature drying oven at 25℃ and dry for 48 hours.

8. The method according to claim 2, characterized in that, In step (3), the dried rice seeds are sown into the paddy field using mechanical direct seeding.

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