A method for regulating salt tolerance in rice using exogenous nano-silicon

Abstract

This invention provides a method for regulating the salt tolerance of rice using exogenous nano-silicon, belonging to the field of agricultural planting technology. The method includes steps such as preparation of nano-silicon formulations, screening of rice growth stages, application of the formulation, and monitoring of effects. Nano-silicon powder is mixed with dispersants and stabilizers in a specific ratio to prepare the nano-silicon formulation. Two key growth stages are selected: the seedling stage and the booting stage. The formulation is applied using a combination of foliar spraying and root irrigation. The optimal application scheme is determined by monitoring rice physiological indicators and yield traits. This invention significantly enhances the salt stress tolerance of rice by optimizing the nano-silicon formulation and precise application methods. Experiments show that the survival rate of rice under salt stress increases by more than 35%, and the yield increases by 20%–25%, without negatively impacting the soil environment. This method can effectively expand the planting range of rice in saline-alkali land and provide technical support for increasing grain production.

Description

Technical Field

[0001] This invention belongs to the field of agricultural technology, and relates to rice, specifically a method for regulating the salt tolerance of rice using exogenous nano-silicon. Background Technology

[0002] Globally, saline-alkali land is widespread, and while my country possesses abundant saline-alkali land resources, their utilization rate is low. Soil salinization has become a key environmental stressor restricting rice production. Salt stress leads to difficulties in water and nutrient absorption by rice roots, osmotic pressure imbalance in cells, and increased oxidative stress, resulting in inhibited growth, reduced tillering, decreased grain filling rate, and in severe cases, plant death. Therefore, improving the salt tolerance of rice is an important way to develop and utilize saline-alkali land and ensure food security.

[0003] Currently, rice salt tolerance regulation technologies mainly include variety selection, soil improvement, and the application of exogenous regulators. Variety selection has a long cycle and limited adaptability, making it difficult to quickly address salinization problems in different regions. Soil conditioners (such as gypsum and humic acid) can reduce soil salinity, but they are costly, slow-acting, and prone to damaging soil structure. Exogenous regulators have received widespread attention due to their ease of use and rapid effects. Among them, silicon, as a beneficial element for rice growth, has potential advantages in enhancing crop stress resistance.

[0004] In existing technologies, the use of exogenous silicon to regulate rice salt tolerance mostly employs ordinary silicon sources, which suffers from low silicon absorption rate and unstable formulations prone to stratification. Furthermore, these methods are often applied at a single time, failing to precisely regulate the salt-sensitive growth stages of rice, resulting in limited salt tolerance effects and making it difficult to meet the needs of large-scale planting in saline-alkali land. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a method for regulating the salt tolerance of rice using exogenous nano-silicon. The technical problem this invention aims to solve is that existing exogenous silicon regulation technologies suffer from low silicon source utilization, poor formulation stability, and inaccurate application timing and methods, resulting in poor salt tolerance effects.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for regulating salt tolerance in rice using exogenous nano-silicon includes the following steps: S1. Preparation of nano-silicon formulations: Select particles with a diameter of 50–100 nm, purity ≥ 99.0%, and specific surface area ≥ 50 m². 2Using nano-silica powder with a content of Pb, Cd, and Hg ≤0.001% per gram as raw material, the ingredients are precisely formulated according to the following weight percentages: 2.0%–3.5% nano-silica powder, 0.3%–0.8% dispersant (sodium dodecylbenzenesulfonate), 0.1%–0.3% stabilizer (xanthan gum), and the balance being deionized water. First, add the dispersant and stabilizer to the deionized water and stir at 300–500 r / min for 10–15 min under constant temperature of 25–30℃ until completely dissolved. Then, slowly add the nano-silica powder and ultrasonically disperse it at 200–300W power for 20–30 min, stirring once every 5 min during the process, to obtain a uniform and stable nano-silica preparation. Finally, adjust the pH value of the preparation to 6.5–7.5 with 0.1 mol / L dilute hydrochloric acid or sodium hydroxide. If no stratification or precipitation occurs after standing for 24 h, the preparation is considered qualified. The nano-silicon in this formulation has good dispersibility and uniform particle size, which can significantly improve the absorption and utilization rate of silicon in rice, increasing it by 40% to 60% compared with ordinary silicon sources.

[0007] S2. Pretreatment during the rice growth period: Select rice seedlings with a height of 15-20cm, 3-4 leaves, and a fresh weight of ≥3g per plant, and uniform growth. Transplant the seedlings into saline-alkali simulated soil containing 0.3%-0.5% sodium chloride. Acclimate the seedlings for 3-5 days under conditions of 25-30℃, light intensity of 30,000-40,000 lux, light duration of 12h / d, and relative humidity of 70%-80%. During this period, water daily to maintain soil moisture content at 60%-70% of field capacity, allowing the seedlings to initially perceive the salt stress environment. The booting stage is a sensitive period for rice to salt stress. Stress treatment should be carried out under soil salinity of 0.4%-0.6%. Stop watering one day before treatment to reduce soil moisture content to 60%-70% of field capacity, facilitating subsequent absorption of the formulation.

[0008] S3. Formulation Application: A combined application method of foliar spraying and root irrigation is adopted to ensure the absorption of silicon through multiple pathways. The application concentration during the seedling stage is 150-200 mg / L. For foliar spraying, an atomizing nozzle is used with a droplet size of 50-100 μm to evenly cover both sides of the leaves. The spraying amount is 50-80 mL / m². If it rains within 4 hours after spraying, the original dosage should be applied again. Root irrigation is carried out after an interval of 24 hours. Water slowly in a circular motion along the root distribution area 5-8 cm from the base of the plant. The irrigation amount is 100-150 mL / plant to avoid direct rinsing of the roots and causing damage. During the heading stage, the application concentration is increased to 200-250 mg / L. The foliar spraying amount is 80-120 mL / m², focusing on spraying the flag leaf and the second leaf from the top. Root irrigation is carried out after an interval of 48 hours. The irrigation amount is 150-200 mL / plant. Both applications should be performed on cloudy days or in the evening after 4:00 PM to avoid strong sunlight causing the formulation to evaporate and be lost, thus affecting the application effect.

[0009] S4. Field Management and Monitoring: After application, maintain soil moisture content at 70%–80% of field capacity. When planting in saline-alkali land, reduce the salinity of the topsoil by flood irrigation every 15–20 days, with a irrigation volume of 300–500 m³ per acre. 3 Physiological indicators were monitored at 7 and 15 days after application. The chlorophyll content of functional leaves was measured using a SPAD-502 instrument to reflect photosynthetic capacity; the malondialdehyde content in leaves was measured using the thiobarbituric acid method to assess the degree of oxidative damage; and root activity was measured using the TTC method to determine root absorption function. At maturity, traits such as the number of effective panicles, seed setting rate, thousand-grain weight, and yield were measured to comprehensively evaluate the salt tolerance regulation effect.

[0010] S5. Effect Evaluation and Optimization: When the chlorophyll content of rice leaves is ≥45 SPAD, the malondialdehyde content is ≤15 nmol / g·FW, and the root activity is ≥200 μg / g·h, the salt tolerance regulation effect is considered to have met the standard. If the malondialdehyde content is >15 nmol / g·FW or the root activity is <200 μg / g·h, a supplementary application of 150-200 mg / L formulation is required after 7 days. For plots with different salinity levels, when the soil salinity is ≥0.6%, one additional application is required during the seedling stage and the booting stage, with the concentration increased to 250-300 mg / L. Mature rice must meet the following criteria: effective panicle number ≥180,000 / mu, grain filling rate ≥85%, thousand-grain weight ≥25g, and yield increased by 20%-25% compared to the untreated group to be considered qualified salt-tolerant and yield-increasing rice.

[0011] Furthermore, the specific surface area of ​​the nano-silicon powder is ≥50m². 2 The content of heavy metal impurities is extremely low (Pb, Cd, and Hg are all ≤0.001%), which avoids pollution to the soil and rice and ensures the quality and safety of agricultural products.

[0012] Furthermore, the foliar spray can be mixed with conventional rice foliar fertilizers (such as potassium dihydrogen phosphate). When mixing, the foliar fertilizer should first be diluted to the recommended concentration (0.2% to 0.3%), and then the nano-silicon preparation should be added and stirred evenly to improve fertilization efficiency. However, it should not be mixed with alkaline pesticides (such as Bordeaux mixture) to prevent the nano-silicon from precipitating and becoming ineffective.

[0013] Furthermore, the rice varieties include indica rice, japonica rice, and hybrid rice. Due to differences in salt tolerance among varieties, the application concentration can be adjusted appropriately: hybrid rice has stronger salt tolerance, so the application concentration can be reduced by 10% to 15%, while indica rice has weaker salt tolerance, so the application concentration can be increased by 5% to 10% to achieve the best control effect.

[0014] Furthermore, when planting in saline-alkali land, straw return technology can be combined with the application of 300-500 kg of decomposed straw per mu to reduce soil bulk density and improve soil water and fertilizer retention capacity. The synergistic effect with nano-silicon preparations can enhance the salt tolerance of rice by 15%-20%.

[0015] Compared with existing technologies, the method of regulating rice salt tolerance using exogenous nano-silicon of the present invention has the following advantages: 1. Technical Performance Advantages: Utilizing high-purity nano-silica powder with a particle size of 50-100 nm, combined with sodium dodecylbenzenesulfonate dispersant and xanthan gum stabilizer, the formulation exhibits no stratification after 24 hours of standing, demonstrating a dispersion stability more than 60% higher than ordinary silicon formulations. Ultrasonic dispersion technology achieves 90% uniformity in nano-silica particle size, with root and leaf absorption rates reaching 35% and 28%, respectively, representing a 4-5 times improvement compared to ordinary silicon sources (8% root absorption and 5% leaf absorption). After precise regulation during key growth stages, chlorophyll content in rice leaves under salt stress was maintained at 45-50 SPAD, a 22%-30% increase compared to the untreated group; malondialdehyde (MDA) content was controlled at 10-15 nmol / g·FW, a 40%-50% decrease compared to the untreated group; root vitality increased by 60%-80%, effectively ensuring photosynthesis and nutrient absorption functions. The survival rate of rice under salt stress increased from 50%-60% using conventional techniques to over 85%.

[0016] 2. Economic Application Value: The single application of nano-silicon preparation is only 0.2-0.3 kg per mu, with a total application of 0.5-1.0 kg throughout the entire growth period. The raw material cost is only 15-25 yuan per mu, which is 75%-85% lower than that of traditional silicon fertilizer (50-100 kg per mu, costing 80-150 yuan). At the same time, this method increases the effective panicle number of rice in saline-alkali land by 18%-25%, the seed setting rate by 12%-18%, the thousand-grain weight by 8%-12%, and the overall yield by 20%-25%. Based on the original yield of 300 kg of rice per mu in saline-alkali land and a purchase price of 3 yuan / kg, the income per mu will increase by 180-225 yuan, with an input-output ratio of 1:7-1:9, significantly improving the economic benefits of planting in saline-alkali land.

[0017] 3. Ecological and Environmental Benefits: The formulation uses a neutral formula (pH 6.5–7.5), which will not change the soil pH with long-term application. Furthermore, the nano-silica powder has extremely low heavy metal content (Pb, Cd, and Hg are all ≤0.001%), avoiding the risk of heavy metal accumulation in the soil. When used in conjunction with straw return technology, it can reduce soil bulk density by 10%–15%, increase organic matter content by 15%–20%, and enhance soil water and fertilizer retention capacity by 20%–30%. This allows for simultaneous improvement and ecological restoration of saline-alkali land, reducing the damage to soil structure caused by chemical amendments and meeting the needs of green agricultural development. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for regulating the salt tolerance of rice using exogenous nano-silicon, according to the present invention. Detailed Implementation

[0019] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0020] like Figure 1 As shown, a method for regulating salt tolerance in rice using exogenous nano-silicon includes the following steps: S1. Preparation of Nano-Silica Formulation: Nano-silica powder with a particle size of 80nm and a purity of 99.5% was selected and formulated according to the following weight percentages: 3.0% nano-silica powder, 0.5% sodium dodecylbenzenesulfonate, 0.2% xanthan gum, and 96.3% deionized water. At 28℃, the dispersant and stabilizer were added to the deionized water and stirred for 12 minutes until dissolved. After adding the nano-silica powder, it was ultrasonically dispersed at 250W for 25 minutes. The pH was adjusted to 7.0, and the mixture was allowed to stand for 24 hours without stratification, thus obtaining the nano-silica formulation.

[0021] S2. Pretreatment during rice growth period: Select japonica rice seedlings with a plant height of 18cm, 4 leaves, fresh weight of ≥3g per plant and uniform growth, and transplant them into saline-alkali simulated soil containing 0.4% sodium chloride. Adapt to the environment for 4 days at a temperature of 28℃, light intensity of 35000 lux, light duration of 12h / d, and relative humidity of 75%. During the booting stage, stress treatment was carried out under the condition of soil salinity of 0.5%, and watering was stopped 1 day before treatment.

[0022] S3. Application of the formulation: During the seedling stage, the concentration is 200 mg / L. In the evening, the foliar spray is applied using a misting nozzle at a rate of 60 mL / m². 24 hours later, the roots are irrigated with 120 mL / plant in a ring. During the booting stage, the concentration is 250 mg / L. The foliar spray is applied at a rate of 100 mL / m². 48 hours later, the roots are irrigated with 180 mL / plant.

[0023] S4. Field Management and Monitoring: Maintain soil moisture content at 75% and leach the soil every 18 days; 7 days after application, measure chlorophyll content (48 SPAD), malondialdehyde content (12 nmol / g·FW), and root activity (220 μg / g·h); 15 days later, the three indicators were 50 SPAD, 10 nmol / g·FW, and 230 μg / g·h, respectively, all meeting the standards.

[0024] S5. Effect evaluation: At maturity, the effective number of spikelets was 192,000 / mu, the seed setting rate was 88%, and the thousand-grain weight was 26.5g. The yield was 23% higher than that of the untreated group, which met the qualified standard.

[0025] Working principle: The core mechanism of this invention in regulating the salt tolerance of rice using exogenous nano-silicon includes the synergistic effects of three aspects: physical barrier construction, osmotic balance regulation, and antioxidant system enhancement. 1. Due to its small particle size (50-100nm) and large specific surface area, nano-silicon is easily absorbed by rice roots and leaves, depositing on the cell wall surface to form a silicified layer physical barrier, reducing sodium ion concentration (Na₂O₃). + 1. Nano-silicon facilitates transmembrane absorption of salt ions, while simultaneously enhancing cell wall mechanical strength to resist cell rupture caused by salt stress; 2. Nano-silicon promotes the synthesis of osmotic regulators such as proline and soluble sugars in rice roots, increasing cell sap osmotic pressure, alleviating cell dehydration under salt stress, and maintaining the root system's ability to absorb water and nutrients; 3. Nano-silicon activates the activity of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD) in rice, reducing the accumulation of reactive oxygen species induced by salt stress, reducing the production of malondialdehyde (a product of membrane lipid oxidation), protecting the structural integrity of organelles such as chloroplasts and mitochondria, and maintaining normal photosynthesis and energy metabolism. Simultaneously, by selecting two key salt stress periods—the seedling stage (3-4 leaf stage, a critical period for root development) and the booting stage (a sensitive period for reproductive growth)—a combination of foliar spraying and root irrigation is used to ensure rapid absorption of nano-silicon through multiple pathways, achieving precise stress resistance regulation at different growth stages.

[0026] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for regulating salt tolerance in rice using exogenous nano-silicon, characterized in that, Includes the following steps: S1. Preparation of nano-silicon formulation: Select nano-silicon powder with a particle size of 50-100nm as raw material, and mix it according to the following weight percentages: 2.0%-3.5% nano-silicon powder, 0.3%-0.8% dispersant, 0.1%-0.3% stabilizer, and the balance is deionized water. First, add the dispersant and stabilizer to the deionized water and stir to dissolve. Then, slowly add the nano-silicon powder and disperse it by ultrasonication for 20-30 minutes to obtain a uniform and stable nano-silicon formulation. Adjust the pH value of the formulation to 6.5-7.

5. The dispersant is sodium dodecylbenzenesulfonate and the stabilizer is xanthan gum. S2. Pretreatment of rice during growth period: Select rice seedlings with uniform growth and pretreat them at the 3-4 leaf stage and the booting stage. Transplant the rice seedlings into saline-alkali simulated soil containing 0.3%-0.5% sodium chloride and allow them to adapt for 3-5 days. During the booting stage, stress treatment is carried out under soil salinity of 0.4%-0.6%. Stop watering 1 day before treatment. S3. Application of formulation: Apply nano-silicon formulation by combining foliar spraying and root irrigation. During the seedling stage, the concentration is 150-200 mg / L, and the foliar spraying amount is 50-80 mL / m². After spraying, irrigate the roots 24 hours later, with an irrigation amount of 100-150 mL / plant. During the booting stage, the concentration is 200-250 mg / L, and the foliar spraying amount is 80-120 mL / m². After 48 hours, irrigate the roots 150-200 mL / plant. Apply on cloudy days or in the evening to avoid strong sunlight. S4. Field Management and Monitoring: After application, maintain soil moisture content at 70%–80% of field capacity. When planting in saline-alkali land, regularly use leaching to reduce the salinity of the topsoil. Monitor chlorophyll content, malondialdehyde content and root activity in rice leaves 7 days and 15 days after application. At maturity, measure yield traits such as effective panicle number, seed setting rate and thousand-grain weight. S5. Effect evaluation: When the chlorophyll content of rice leaves is ≥45SPAD, the malondialdehyde content is ≤15nmol / g·FW, and the root activity is ≥200μg / g·h, the salt tolerance regulation effect is judged to be up to standard. When the number of effective panicles of mature rice is ≥180,000 / mu, the seed setting rate is ≥85%, and the thousand-grain weight is ≥25g, it is considered a qualified salt-tolerant and yield-increasing rice.

2. The method for regulating rice salt tolerance using exogenous nano-silicon according to claim 1, characterized in that, The purity of the nano-silicon powder is ≥99.0%, and the specific surface area is ≥50m². 2 / g, and free of heavy metal impurities, with Pb, Cd, and Hg contents all ≤0.001%.

3. The method for regulating rice salt tolerance using exogenous nano-silicon according to claim 1, characterized in that, The foliar spraying uses an atomizing nozzle with a droplet size of 50-100μm. During spraying, the droplets are evenly covered on both sides of the leaves. Root irrigation is applied in a ring along the root distribution area to avoid directly eroding the root system.

4. The method for regulating rice salt tolerance using exogenous nano-silicon according to claim 1, characterized in that, When planting in saline-alkali land, if the soil salinity is ≥0.6%, the preparation should be applied once more during the seedling stage and once more during the booting stage, with the application concentration increased to 250-300 mg / L.

5. The method for regulating rice salt tolerance using exogenous nano-silicon according to claim 1, characterized in that, In step S4, chlorophyll content was measured using a SPAD instrument, malondialdehyde content was measured using the thiobarbituric acid method, and root activity was measured using the TTC method.

6. The method for regulating rice salt tolerance using exogenous nano-silicon according to claim 1, characterized in that, The formulation can be mixed with conventional foliar fertilizers for rice. When mixing, the foliar fertilizer should be diluted to the recommended concentration first, and then the nano-silicon formulation should be added and stirred evenly. It should not be mixed with alkaline pesticides.

7. The method for regulating rice salt tolerance using exogenous nano-silicon according to claim 1, characterized in that, The rice varieties mentioned include indica rice, japonica rice, and hybrid rice. The application concentration of hybrid rice can be reduced by 10% to 15%, while the application concentration of indica rice can be increased by 5% to 10%.

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