Seedling culture substrate for weakening cadmium absorption capacity of rice and preparation method and application thereof

Abstract

The application provides a preparation and application method of seedling cultivation substrate weakening the cadmium absorption capacity of rice. The seedling cultivation substrate comprises a formula seedling raising substrate and a manganese additive; the manganese additive is a solution prepared by mixing manganese sulfate monohydrate and water at a ratio of 0.6 g:200 mL; the formula seedling raising substrate comprises 30-60 parts of peat, 15-25 parts of coconut husk, 15-25 parts of vermiculite and 10-25 parts of yellow clay. The preparation method comprises the following steps: uniformly mixing the peat, coconut husk, vermiculite and yellow clay according to the weight ratio to obtain a mixture, uniformly spraying the manganese additive on the mixture according to the proportion of 1 kg of substrate adding 1 L of manganese additive, adjusting the pH of the substrate to 4.9-6.4, and finally placing the seedling cultivation substrate in an oven at 45-55 DEG C for 12-36 h. The seedling cultivation substrate overcomes the defects of large amount of manganese fertilizer in soil application, environmental risk and unstable cadmium reduction efficiency of foliar spraying of manganese fertilizer, has a good cadmium reduction effect on rice brown rice, and has a good field application prospect.

Description

Technical Field

[0001] This invention relates to the field of safe production technology in farmland with moderate to mild pollution, and in particular to the safe production technology of rice in farmland with moderate to mild cadmium pollution. Background Technology

[0002] Current research on cadmium-contaminated soil remediation and safe utilization is extensive, including the breeding of low-cadmium-accumulating varieties, the development and application of passivating agents, and adjustments to planting systems and agronomic techniques. Low-cadmium-accumulating varieties often struggle to simultaneously achieve high yield and quality, resulting in limited large-scale practical application. Passivating agents are widely developed, including lime, organic fertilizers, biochar, sepiolite, and hydroxyapatite. These agents primarily work by increasing soil pH, altering cadmium speciation, and reducing the available cadmium content in the soil, thus mitigating cadmium absorption by rice to some extent. However, most are costly, and long-term application can negatively impact soil physicochemical properties; for example, long-term lime application can cause soil compaction, leading to reduced fertility and decreased crop yield. Agronomic techniques are relatively simple and easy to implement; effective cadmium reduction can also be achieved through field water management and the application of micronutrient fertilizers.

[0003] Manganese not only participates in the formation of the iron film on the rice root surface (preventing cadmium from entering the rice root system), but manganese and cadmium also share the same transporter protein (such as OsNramp5) in rice. Therefore, applying manganese fertilizer shows promising potential in inhibiting cadmium accumulation in rice. Currently, the most common fertilization methods are basal application to the soil and foliar spraying. However, because exogenous manganese is rapidly oxidized and fixed after being applied to the soil, there is a risk of manganese exceeding the standard when applied to the soil. Furthermore, foliar spraying of manganese fertilizer is easily affected by weather and the waxy layer on the leaf surface, resulting in highly unstable cadmium reduction effects, with a cadmium reduction rate of only 5.5%–9.3%. Existing literature reports the use of manganese-enriched nutrient solutions (250 μmol·L⁻¹) to reduce cadmium levels. -1 Mn 2+ Manganese-enriched seedlings were cultivated, resulting in a 31.7% decrease in cadmium content in brown rice after transplanting. However, this hydroponic method cannot be applied on a large scale in the field. Currently, there is a lack of cadmium-reducing seedling substrate products suitable for rice seedling cultivation. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for preparing and applying a seedling cultivation substrate that weakens rice's ability to absorb cadmium. The seedling cultivation substrate provided by this invention not only reduces the cadmium content in brown rice but also meets rice's requirements for trace elements, without causing resource waste or secondary risks.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A seedling cultivation substrate that weakens the cadmium uptake capacity of rice, the seedling cultivation substrate comprising a formulated nutrient substrate and a manganese additive: The nutrient matrix of the formula includes the following components in parts by weight: 30-60 parts peat, 15-25 parts coconut coir, 15-25 parts vermiculite, 10-25 parts yellow clay, with a pH of 4.9-6.4. The manganese additive uses water as a solvent, specifically manganese sulfate monohydrate; The ratio of the manganese additive to the seedling substrate is 0.5~1 mL:0.5~1 g.

[0006] In the seedling cultivation substrate, the peat moss accounts for 40-50 parts by weight, the coconut coir accounts for 18-22 parts by weight, the vermiculite accounts for 18-22 parts by weight, and the yellow clay accounts for 15-21 parts by weight.

[0007] In the seedling cultivation substrate, the peat moss comprises 40 parts by weight, the coconut coir comprises 20 parts by weight, the vermiculite comprises 20 parts by weight, and the yellow clay comprises 20 parts by weight.

[0008] The peat and vermiculite have particle sizes of 2~20 mm and 2~6 mm, respectively, and the yellow clay has a particle size of 2~5 mm.

[0009] A method for preparing a seedling cultivation substrate that weakens the cadmium uptake capacity of rice includes the following steps: S1. Mix peat, vermiculite, coconut coir and yellow clay in a certain proportion to obtain a mixture; S2. Mix manganese sulfate monohydrate with water to obtain a manganese additive; S3. The manganese additive obtained in step S2 is evenly sprinkled into the mixture obtained in step S1, and then placed in an oven to dry for 12-36 hours to obtain a manganese-rich seedling substrate, which is the seedling cultivation substrate that weakens the cadmium absorption capacity of rice.

[0010] In step S3, the drying temperature is 45~55℃ and the drying time is 12~36 h.

[0011] The manganese additive mentioned in step S3 is a manganese sulfate monohydrate solution, and the ratio of manganese additive to water is 0.6 g: 200 mL.

[0012] A method for applying a seedling cultivation substrate that weakens the cadmium absorption capacity of rice includes the following steps: Select a 9-inch conventional rice seedling tray, add 1.5-2L of manganese-enriched seedling substrate to each tray, after soaking and germinating rice seeds using conventional methods, evenly sow 110-160 g of seeds into each tray, cultivate in a moist environment for about 20-25 days, then transplant the manganese-enriched seedlings into cadmium-contaminated soil, and harvest the rice after it matures. Beneficial effects

[0013] The peat in this invention can effectively increase the organic matter content, and the peat itself contains a variety of nutrients needed for crop growth; coconut coir and vermiculite can improve the porosity of the seedling substrate and have a certain water and fertilizer retention effect; yellow clay can improve the substrate bulk density and porosity.

[0014] The active ingredient of the manganese additive in this invention is Mn, which is required for crop growth. 2+ By adding an appropriate concentration of Mn required for crop growth 2+ Strengthening root system's resistance to Mn in manganese-rich matrix 2+ The absorption of Mn by rice after transplanting is reduced. 2+ This method meets the demand for manganese fertilizer, has a good cadmium reduction effect on brown rice, avoids resource waste and secondary risks caused by excessive application of manganese fertilizer, and has good prospects for field application. Detailed Implementation

[0015] This invention provides a seedling cultivation substrate that weakens the cadmium absorption capacity of rice. The seedling cultivation substrate includes a formulated nutrient substrate and a manganese additive. The formulated nutrient substrate includes the following components in parts by weight: 30-60 parts peat, 15-25 parts coconut coir, 15-25 parts vermiculite, 10-25 parts yellow clay, with a pH of 4.9-6.4. The manganese additive is manganese sulfate monohydrate, and the ratio of manganese sulfate monohydrate to water is 0.6 g: 200 mL.

[0016] Unless otherwise specified, the present invention does not have any special requirements for the source of each component in the formula nutrient matrix, and commercially available products well known to those skilled in the art can be used.

[0017] In the nutrient matrix of the formula described in this invention, the peat moss is 30-60 parts by weight, preferably 40-50 parts, and more preferably 40 parts.

[0018] In the nutrient matrix of the formula described in this invention, the weight parts of coconut coir are 15-25 parts, preferably 18-22 parts, and more preferably 20 parts.

[0019] In the nutrient matrix of the formula described in this invention, the vermiculite is present in a weight ratio of 15-25 parts, preferably 18-22 parts, and more preferably 20 parts.

[0020] In the nutrient matrix of the formula described in this invention, the weight parts of yellow mud are 10-25, preferably 15-21, and more preferably 20.

[0021] In this invention, by adding a suitable concentration of manganese sulfate monohydrate solution to the formula nutrient substrate, the cadmium tolerance of rice seeds during seedling cultivation can be improved, thereby obtaining seedlings with strong cadmium tolerance and reducing the cadmium content in brown rice.

[0022] In this invention, the pH of the seedling cultivation substrate is 4.9-6.4, preferably 5.0-5.5, and more preferably 5.1. This invention does not specifically limit the reagents used to adjust the pH of the seedling cultivation substrate; hydrochloric acid and sodium hydroxide are preferred for adjusting the pH of the seedling cultivation substrate.

[0023] In this invention, the peat has a particle size of 5-20 mm, the vermiculite has a particle size of 2-6 mm, and the yellow clay has a particle size of 2-5 mm. Preferably, it comprises peat with a particle size of 5-15 mm, vermiculite with a particle size of 3-5.5 mm, and yellow clay with a particle size of 2.5-4.5 mm. More preferably, it comprises peat with a particle size of 10 mm, vermiculite with a particle size of 5 mm, and yellow clay with a particle size of 4 mm. The source of the raw materials for the seedling cultivation substrate is not limited in this invention and its embodiments; conventional raw materials well-known to those skilled in the art can be used. This invention strengthens the rice root system's resistance to Mn by adding a suitable concentration of manganese sulfate monohydrate solution. 2+ The absorption of these substances further enhances rice's cadmium tolerance.

[0024] This invention also discloses a method for preparing the seedling cultivation substrate, comprising the following steps: S1. Mix peat, vermiculite, coconut coir and yellow clay in a certain proportion to obtain a mixture; S2. Mix manganese sulfate monohydrate with water to obtain a manganese additive; S3. The manganese additive obtained in step S2 is evenly sprinkled into the mixture obtained in step S1, and then placed in an oven to dry for 12-36 hours to obtain a manganese-rich seedling substrate, which is the seedling cultivation substrate that weakens the cadmium absorption capacity of rice.

[0025] In step S3, the drying temperature is 45~55℃ and the drying time is 12~36 h.

[0026] The manganese additive mentioned in step S3 is a manganese sulfate monohydrate solution, and the ratio of manganese additive to water is 0.6 g: 200 mL.

[0027] In this invention, the drying temperature of the mixture is preferably 45~55℃, more preferably 50℃; the drying time is preferably 12~36 h, more preferably 24 h.

[0028] This invention also provides a method for applying the seedling cultivation substrate described above in reducing cadmium absorption by rice, comprising the following steps: selecting a 9-inch conventional rice seedling tray, adding 1.5-2L of seedling cultivation substrate to each tray, after soaking and germinating rice seeds using conventional methods, evenly scattering 110-160g of seeds into each tray, moistening and cultivating for about 20-25 days, then transplanting the manganese-rich seedlings into cadmium-contaminated soil, and harvesting after the rice matures.

[0029] The present invention does not limit the source of the seedling tray; any conventional commercially available product known to those skilled in the art can be used.

[0030] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of the preparation and application method of a seedling cultivation substrate that weakens the cadmium absorption capacity of rice provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1 A seedling cultivation substrate that weakens the cadmium uptake capacity of rice, the substrate being composed of a formulated nutrient substrate and a manganese additive.

[0032] In this embodiment, the raw material ratio of the nutrient matrix is: 30 parts peat, 15 parts vermiculite, 15 parts coconut coir and 10 parts yellow clay.

[0033] The preparation method is as follows: S1. Mix 30 parts peat, 15 parts vermiculite, 15 parts coconut coir and 10 parts yellow clay to obtain a mixture, wherein the particle sizes of peat and vermiculite are 5 mm and 3 mm, respectively, the particle size of yellow clay is 2.5 mm, and the pH of the matrix is ​​4.9. S2. Manganese sulfate monohydrate is mixed with water at a ratio of 0.61 g: 200 mL to obtain a manganese additive solution; S3. Sprinkle the manganese additive solution evenly into the mixture and dry it in a 45℃ oven for 12 hours to obtain the seedling cultivation substrate.

[0034] Example 2 In this embodiment, the raw material ratio of the nutrient matrix is: 40 parts peat, 20 parts vermiculite, 20 parts coconut coir and 20 parts yellow clay.

[0035] S1. Mix 40 parts peat, 20 parts vermiculite, 20 parts coconut coir and 20 parts yellow clay to obtain a mixture, wherein the particle sizes of peat and vermiculite are 10 mm and 5 mm, respectively, the particle size of yellow clay is 4 mm, and the pH of the matrix is ​​5.1. S2. Manganese sulfate monohydrate is mixed with water at a ratio of 0.61 g: 200 mL to obtain a manganese additive solution; S3. Sprinkle the manganese additive solution evenly into the mixture and dry it in a 50℃ oven for 12 hours to obtain the seedling cultivation substrate.

[0036] Example 3 In this embodiment, the raw material ratio of the nutrient matrix is: 60 parts peat, 25 parts vermiculite, 25 parts coconut coir and 25 parts yellow clay.

[0037] S1. Mix 60 parts peat, 25 parts vermiculite, 25 parts coconut coir and 25 parts yellow clay to obtain a mixture, wherein the particle sizes of peat and vermiculite are 20 mm and 6 mm, respectively, the particle size of yellow clay is 5 mm, and the pH of the matrix is ​​6.4. S2. Manganese sulfate monohydrate is mixed with water at a ratio of 0.61 g: 200 mL to obtain a manganese additive solution; S3. Sprinkle the manganese additive solution evenly into the mixture and dry it in a 55℃ oven for 36 hours to obtain the seedling cultivation substrate.

[0038] Comparative Example A method similar to Example 1, except that the seedling substrate used is a conventional seedling substrate (components: 60 parts peat, 20 parts coconut coir, 20 parts vermiculite).

[0039] Application examples The tested soil had a pH of 4.8, a total cadmium content of 0.68 mg / kg, and an available Cd content of 0.11 mg / kg. The tested rice variety was Longjingyou 1, an indica three-line hybrid rice with a full growth period of 128 days. 140g of germinated seeds were sown in the substrates of Application Example 1, Application Example 2, Application Example 3, and the comparative example for seedling cultivation. After 25 days of moist cultivation, the seedlings were transplanted into the field soil, and the field water and fertilizer management measures were consistent with the traditional methods.

[0040] Table 1 shows the manganese content of rice before and after transplanting: Table 1. Cd content in different parts of rice after control and seedling cultivation substrate treatment. Comparative Example 0.31±0.10 Example 1 0.19±0.11 38.7% Example 2 0.17±0.08 45.2% Example 3 0.18±0.08 41.9% Note: Except for the treatment method, all other conventional cultivation methods are the same for the groups in the table.

[0041] As can be seen from Table 1, the rice cultivated in Examples 1-3 using the seedling cultivation substrate prepared in this invention showed a 38.7% to 45.2% decrease in brown rice Cd content compared to the rice cultivated in the comparative example.

Claims

1. A seedling cultivation substrate that weakens the cadmium uptake capacity of rice, characterized in that: The seedling cultivation substrate includes a formulated nutrient substrate and a manganese additive: The nutrient matrix of the formula includes the following components in parts by weight: 30-60 parts peat, 15-25 parts coconut coir, 15-25 parts vermiculite, 10-25 parts yellow clay, with a pH of 4.9-6.

4. The manganese additive uses water as a solvent, specifically manganese sulfate monohydrate; The ratio of the manganese additive to the seedling substrate is 0.5~1 mL:0.5~1 g; In the seedling cultivation substrate, the peat moss is 40-50 parts by weight, the coconut coir is 18-22 parts by weight, the vermiculite is 18-22 parts by weight, and the yellow clay is 15-21 parts by weight. In the seedling cultivation substrate, the peat is 40 parts by weight, the coconut coir is 20 parts by weight, the vermiculite is 20 parts by weight, and the yellow clay is 20 parts by weight. The peat and vermiculite have particle sizes of 2~20 mm and 2~6 mm, respectively, and the yellow clay has a particle size of 2~5 mm.

2. A method for preparing a seedling cultivation substrate that weakens the cadmium absorption capacity of rice as described in claim 1, characterized in that, Includes the following steps: S1. Mix peat, vermiculite, coconut coir and yellow clay in a certain proportion to obtain a mixture; S2. Mix manganese sulfate monohydrate with water to obtain a manganese additive; S3. The manganese additive obtained in step S2 is evenly sprinkled into the mixture obtained in step S1, and then placed in an oven to dry for 12-36 hours to obtain a manganese-rich seedling substrate, which is the seedling cultivation substrate that weakens the cadmium absorption capacity of rice.

3. The preparation method according to claim 2, characterized in that, In step S3, the drying temperature is 45~55℃ and the drying time is 12~36 h.

4. The preparation method according to claim 2, characterized in that, The manganese additive mentioned in step S3 is a manganese sulfate monohydrate solution, and the ratio of manganese additive to water is 0.6 g: 200 mL.

5. A method for applying a seedling cultivation substrate that weakens the cadmium absorption capacity of rice, characterized in that, Includes the following steps: Select a 9-inch standard rice seedling tray, add 1.5-2L of manganese-enriched seedling substrate to each tray, and after the rice seeds have been soaked and germinated using the conventional method, evenly sow 110-160 g of seeds into each tray, moisten and cultivate for about 20-25 days, and then transplant the manganese-enriched seedlings into cadmium-contaminated soil. Harvest the rice after it matures.