Power-on device and method for establishing rice nano-silicon defense barrier before rice transplanting

Abstract

The invention discloses an electrifying device and method for establishing a rice nano-silicon defense barrier before rice transplanting. When the device is used, a rice root system can be soaked in an electrified nutrient solution containing nano silicon before rice transplanting, and a silicon barrier can be formed at the root after 30 minutes. The growth condition of the rice under heavy metal stress is remarkably improved, and absorption of heavy metal on the overground part is inhibited. In a stress experiment for 5 days, the effect of electrically stimulating the polymerization of the nano silicon is better than that of applying the nano silicon to the traditional substrate. In addition, transcriptional analysis further reveals that the gene regulation effect of the electrical stimulation nanometer silicon is remarkably different from that of pure electrical stimulation. The invention provides a convenient treatment method for improving the stress resistance of rice before rice transplanting.

Description

Technical Field

[0001] The invention belongs to the field of agricultural pre-transplantation treatment, and more specifically, relates to a device and method for establishing an anti-heavy metal defense barrier for rice before transplanting by electrifying a solution containing nano-silicon. Background Art

[0002] Heavy metal pollution in soil caused by industrial emissions, agricultural fertilization and urban waste has become an increasingly serious environmental problem worldwide. The accumulation of chromium, lead, cadmium, mercury, arsenic, etc. in the soil will lead to a decline in soil quality and damage to the ecosystem. Except for a few hyperaccumulator types, most plants do not need heavy metals themselves, so they have not evolved corresponding transport proteins. Heavy metals enter plants mainly through the apoplast pathway, and a few enter through shared transport proteins because of their similar properties to other essential elements. Heavy metals in crops not only affect plant growth and yield, but also pose a threat to human health through the food chain. Therefore, it is particularly important to block more heavy metals in the roots and prevent them from entering the edible aboveground parts of plants to ensure food security.

[0003] Rice planting requires the step of transplanting. Compared with plants at different stages after transplanting, rice seedlings have the worst stress resistance. In addition, the flooded environment of rice fields increases the bioavailability of many heavy metals. If a method can be developed to help rice roots quickly establish a silicon defense barrier before transplanting, it will not only help the growth and stress resistance of rice seedlings, but also lay a good foundation for later growth.

[0004] It has been proven that silicon can enhance the resistance of plants to heavy metal stress. Silicon reduces the absorption of heavy metals by forming a physical barrier, and enhances the antioxidant capacity of plants by increasing the activity of antioxidant enzymes and promoting the synthesis of secondary metabolites. In addition, silicon can also improve the water and nutrient absorption of plants. In recent years, nano-silicon has shown a good effect in enhancing plant stress resistance in agriculture due to its smaller particle size, larger surface area and better absorption effect than traditional fertilizers. However, nano-silicon fertilizers are currently mainly applied to the soil and leaves. There is still a lack of effective means to use nano-silicon to establish a heavy metal defense barrier for rice before transplanting. Summary of the invention

[0005] The purpose of the present invention is to quickly establish a nano-silicon defense barrier for rice and evaluate the role of the barrier in plant resistance to heavy metal stress.

[0006] The technical solutions specifically adopted in the present invention are as follows:

[0007] In a first aspect, the present invention provides a power supply device for establishing a rice nano-silicon defense barrier before transplanting, which includes a power supply device and a coverless container made of a non-conductive material;

[0008] The lidless container is divided into three interconnected chambers by two perforated partitions. The plant chamber for placing rice seedlings is located between the two perforated partitions, and two power supply chambers are located on both sides of the plant chamber. The entire lidless container stores a nutrient solution containing nano-silicon, and the height of the nutrient solution should be able to immerse the root system of the rice seedlings.

[0009] The power supply device includes a battery and positive and negative electrode plates connected to the positive and negative poles of the battery respectively. The positive electrode plate and the negative electrode plate are respectively arranged below the nutrient solution level in two power-on chambers, and are used to apply a voltage to both sides of the root system of the rice seedlings immersed in the nutrient solution to induce the roots to form a nano-silicon barrier.

[0010] As a preferred embodiment of the first aspect, both the positive electrode plate and the negative electrode plate are made of nickel sheets.

[0011] As a preferred embodiment of the first aspect, in the power supply device, the positive and negative electrodes of the battery are respectively connected to two metal clips via wires, and the positive electrode plate and the negative electrode plate are respectively conductively clamped and fixed by the metal clips.

[0012] As a preferred embodiment of the first aspect, the battery is a storage battery with a supply voltage of 8 to 12V.

[0013] As a preferred embodiment of the first aspect, the coverless container is a coverless acrylic plastic box.

[0014] As a preferred embodiment of the above-mentioned first aspect, the nutrient solution is 1 / 4 Kimura B nutrient solution.

[0015] As a preferred embodiment of the first aspect, the concentration of nano-silicon in the nutrient solution is 8-12 mM, and the particle size of nano-silicon is 25-35 nm.

[0016] In a second aspect, the present invention provides a method for establishing a rice nano-silicon defense barrier in front of the seedlings using the power-on device described in any of the schemes of the first aspect, characterized in that the rice seedlings to be planted are placed in the plant chamber with their leaves facing upward and their roots facing downward, and their roots are kept immersed in a nutrient solution containing nano-silicon; then the power supply device is used to apply a voltage of 8 to 12 V to both sides of the roots of the rice seedlings immersed in the nutrient solution for electrical stimulation, and the nano-silicon defense barrier is formed at the roots after maintaining for at least 30 minutes, and then the rice seedlings are taken out.

[0017] As a preference of the above second aspect, the voltage of the electrical stimulation is preferably 12V.

[0018] As a preference of the second aspect above, the electrical stimulation is preferably maintained for 30 minutes.

[0019] In a third aspect, the present invention provides a method for planting rice in heavy metal contaminated soil, which comprises: electrically stimulating the rice seedlings to be planted according to the method described in the second aspect above, and then transplanting them into heavy metal contaminated soil after a nano-silicon defense barrier is formed at the roots, so as to enhance the rice's ability to resist heavy metal stress.

[0020] Compared with the prior art, the present invention has the following beneficial effects: currently, nano-silicon is mainly supplied to plants by leaf spraying or matrix application, but much of the nano-silicon applied to the soil is fixed by the soil and is not absorbed by the plant. In addition, the process of nano-silicon in the soil being deposited in the roots to form a defense barrier is relatively slow, and silicon sprayed by leaves is difficult to be transported to the root system to help the roots establish a defense barrier. The present invention can quickly induce the roots to form a nano-silicon defense barrier within half an hour. Secondly, although nano-silicon can help plants improve their stress resistance, there are also hidden dangers in terms of biosafety and ecological risks. The present invention only needs to add nano-silicon to the device, and does not need to be applied in large quantities to the environment, which not only improves the fertilizer efficiency but also reduces pollution and potential ecological risks. In addition, matrix application of silicon requires a large amount of manpower and material resources, while the device of the present invention is light, easy to operate, requires little manpower, and has safe voltage, which is conducive to promotion to farmers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the device for inducing the establishment of a nano-silicon defense barrier for rice roots by applying electricity in the present invention;

[0022] Figure 2 This is a diagram showing the effect of the root nano-silicon defense barrier established by powering on in an embodiment of the present invention;

[0023] Figure 3 The effect of establishing a root nano-silicon defense barrier by electrification on the hexavalent chromium stress resistance of rice in the embodiment of the present invention; a is the plant height under different treatments, and b is the chromium concentration in the aboveground part under different treatments;

[0024] Figure 4 This is a comparison diagram of the effect of the nano-silicon defense barrier formed by electrical induction and the nano-silicon applied to the substrate in the embodiment of the present invention; a is the plant height under different treatments, and b is the chromium concentration in the aboveground part under different treatments;

[0025] Figure 5 The main gene enrichment pathways for the formation of nano-silicon defense barrier induced by electrical stimulation compared with normal rice and pure electrical stimulation rice. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0027] In the description of the present invention, it is to be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or indirectly connected, that is, there are intermediate elements. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

[0028] like Figure 1 As shown, in an embodiment of the present invention, there is provided an energizing device for establishing a rice nano-silicon defense barrier before transplanting, and the device comprises two main components, namely a power supply device 1 and an uncovered container made of a non-conductive material. The uncovered container is a watertight container made of a non-conductive material, and the specific material is not limited. In this embodiment, the uncovered container is an uncovered rectangular plastic box made of acrylic material, with a thickness of 0.2 mm, and a length, width, and height of 20 cm, 10 cm, and 8 cm, respectively. In addition, three interconnected chambers are formed in the uncovered container by two perforated partitions. The plant chamber 3 for placing rice seedlings is located between the two perforated partitions, and two energizing chambers 2 are located on both sides of the plant chamber 3. In this embodiment, a rectangular PP plastic plate with round holes can be inserted at the 5 cm and 15 cm in the length direction of the rectangular plastic box. The length of the rectangular PP plastic plate is 10 cm and the width is 8 cm. The plant chamber 3 is located between the two plastic plates, and since a series of circular holes are evenly provided on the PP plastic plates, the nutrient solution can flow freely between the plant chamber 3 and the power chambers 2 on both sides. The entire uncovered container stores a nutrient solution containing nano-silicon, and the height of the nutrient solution should be able to submerge the roots of the rice seedlings. The specific height should be adjusted according to the actual situation of the rice seedlings to be treated. The plant chamber 3 provides a temporary placement space for the rice seedlings. In actual application, the rice seedlings can be placed in bundles in the plant chamber 3 to keep the roots submerged in the nutrient solution. No external fixing device is required for fixing, which is convenient for carrying and use.

[0029] In addition, the formula of the nutrient solution stored in the above-mentioned uncovered container should meet the growth requirements of rice, but the specific ingredients can be configured according to actual needs. In an embodiment of the present invention, the nutrient solution can adopt 1 / 4 Kimura B nutrient solution. In addition, the nutrient solution should also be added with nano-silicon required to establish a nano-silicon barrier for the root system. The concentration of nano-silicon in the nutrient solution is preferably 8-12mM, more preferably 10mM, and the nano-silicon particle size is preferably 25-35nm, more preferably 30nm.

[0030] The power supply device 1 comprises a battery and positive and negative electrode plates connected to the positive and negative poles of the battery respectively. The positive electrode plate and the negative electrode plate are respectively arranged below the level of the nutrient solution in the two power-on chambers 2, and are used to apply a voltage to both sides of the root system of the rice seedlings immersed in the nutrient solution to induce the roots to form a nano-silicon barrier.

[0031] In the power supply device 1 of the present embodiment, both the positive electrode plate and the negative electrode plate are made of nickel sheets. The positive and negative electrodes of the power supply are connected to two metal clips through wires, and the positive electrode plate and the negative electrode plate are respectively fixed by the metal clips for conductive clamping. The introduction of the metal clip is to facilitate the replacement and fixing of the nickel sheet. In theory, it is also feasible to directly connect the wire to the metal clip. The power supply device 1 can be powered by a portable battery as a power source, and its output voltage is generally controlled at 8 to 12V, preferably 12V (reference standard GB / T8897.2). In the present embodiment, the power supply device 1 connects the current output by the power supply to the power supply chamber 2 through two wires with metal alligator clips. Two nickel sheets are clamped on the alligator clips to expand the contact area. The electrical stimulation applied to the rice root system will accelerate the deposition of nano-silicon in the nutrient solution on the root surface to form a nano-silicon barrier.

[0032] Therefore, the present invention is based on the above Figure 1 The device shown further provides a method for establishing a rice nano-silicon defense barrier before the seedlings are grown, which is as follows: the rice seedlings to be planted are placed in the plant chamber 3 with the leaves facing upward and the roots facing downward, and the roots are kept immersed in the nutrient solution containing nano-silicon; then the power supply device 1 is used to apply a voltage of 8 to 12V to both sides of the roots of the rice seedlings immersed in the nutrient solution for electrical stimulation, and the nano-silicon defense barrier is formed at the roots for at least 30 minutes, and then the rice seedlings are taken out. At this time, the roots of the rice seedlings have formed a layer of nano-silicon barrier, which helps to maintain the normal growth of rice under heavy metal stress, increase fresh weight, and reduce the concentration of heavy metals in the aboveground part.

[0033] In the above method, the voltage of electrical stimulation is preferably 12V, and the duration of electrical stimulation is preferably 30 minutes.

[0034] Therefore, the above-mentioned power-on device is portable. When planting rice in heavy metal contaminated soil, the rice seedlings can be treated directly at the planting site, that is, the rice seedlings to be planted are first electrically stimulated according to the above-mentioned method, and then transplanted into heavy metal contaminated soil after a nano-silicon defense barrier is formed at the roots, so as to enhance the rice's ability to resist heavy metal stress.

[0035] The specific implementation and technical effects of the energizing device for electrically stimulating and inducing the formation of a nano-silicon defense barrier for the root system before transplanting of the present invention are described in detail below through several embodiments.

[0036] Example 1

[0037] In this embodiment, using the above Figure 1 The energized device shown builds a nano-silicon defense barrier for the root system and detects the formed silicon barrier.

[0038] Rice seeds (Oryza sativa L.cv. Nipponbare) were sterilized with 10% hydrogen peroxide for 10 minutes, washed three times with deionized water, placed on moist filter paper, and germinated for five days in the dark at 30°C. The rice seedlings were then transferred to a 1 / 4 concentration of Kimura B nutrient solution (pH adjusted to 6) and replaced every seven days. The temperature in the artificial climate chamber was 30°C, the humidity was 55%, and the light and dark time were 14 and 10 hours, respectively. The 14-day-old rice seedlings were used for the electrification experiment.

[0039] In this embodiment, three treatments are set, and the composition of the nutrient solution in the uncovered container and the electrical stimulation method are different, specifically: the control group (CK) is to immerse the rice roots in a 1 / 4 concentration of Kimura B nutrient solution for 30 minutes, the silicon treatment group (NanoSi) is to immerse the rice roots in a 1 / 4 concentration of Kimura B nutrient solution containing 10mM nano silicon (particle size is 30nm) without electricity for 30 minutes, and the electrical treatment group (ENanoSi) is to immerse the rice roots in a 1 / 4 concentration of Kimura B nutrient solution containing 10mM nano silicon, and energize the nutrient solution for 30 minutes (i.e., a 12V voltage is applied between the positive electrode plate and the negative electrode plate in the electrification chamber 2). Then, the root surface is cleaned with 10% EDTA solution and deionized water. After each group completed the 30-minute treatment, a portion of the fresh root segments of the seedlings were cut off, immediately attached to the carbon glue, and freeze-dried with a freeze dryer. Before the test, the roots were sprayed with gold. The silicon deposition on the surface of rice roots in different treatments was observed using SEM-EDS and photographed. Another part of the roots was dried and then digested with HNO3, H2O2 and HF. After the volume was fixed to 20 ml with 4% boric acid (to remove residual HF), the Si element concentration was determined by ICP-OES. Each treatment contained three biological replicates.

[0040] The results of SEM showed that the surface of rice roots not soaked in nano-silicon was very smooth, with no obvious silicon particle deposition ( Figure 2 However, a large amount of nano-silicon was deposited on the rice root surface after the electricity was applied to the nano-silicon for 30 minutes, which was much more than that of the rice root surface after the electricity was applied to the nano-silicon for 30 minutes ( Figure 2 b and c). The roots of each treatment were digested and measured by ICP-OES. It was found that the root silicon concentration of the NanoSi group was 8.6 times that of the CK group, and the root silicon concentration of the ENanoSi group was 2.1 times that of the NanoSi group ( Figure 2 (d) This indicates that the method used in this study can quickly establish a nano-silicon barrier in the rice root system.

[0041] Example 2

[0042] Example 1 has demonstrated the effectiveness of this method in rapidly establishing a nano-silicon barrier in the root system, but the effect of this method on the stress resistance of rice has not been evaluated. Chromium (Cr) is an important industrial mineral resource. However, it is a toxic and mutagenic environmental heavy metal pollutant and is listed as one of the top carcinogens by the International Agency for Research on Cancer. In this example, taking hexavalent chromium stress as an example, the effect of the nano-silicon barrier established by the root system induced by electricity on resisting heavy metal stress was verified.

[0043] Rice was still selected as the plant material, and the seed germination and seedling growth conditions were the same as in Example 1. Three treatments were set up: CK group: 14-day-old rice that had not been treated in advance was planted in a nutrient solution that did not contain chromium; Cr group: rice that had not been treated in advance was planted in a 1 / 4 Kimura B nutrient solution containing 50 μM hexavalent chromium (prepared with potassium dichromate, calculated as chromium); Cr+ENanoSi (i.e., a method of electrical stimulation using the energizing device of the present invention): 12V voltage was applied between the positive electrode plate and the negative electrode plate in the energizing chamber 2, and the rice was soaked in the energized nutrient solution containing 10 mM nano-silicon for 30 minutes, and then planted in a 1 / 4 Kimura B nutrient solution containing 50 μM hexavalent chromium. Three pots were used for each treatment, and four rice plants were planted in each pot. One plant was randomly selected from each pot during the measurement, with a total of three replicates.

[0044] After 5 days, the plant height of each group of rice was measured. The aboveground part of rice was digested with HNO3, H2O2 and HF. After the volume was fixed to 20 ml with 4% boric acid (to remove residual HF), the Cr concentration was determined by ICP-OES.

[0045] The results showed that hexavalent chromium stress inhibited the normal growth of rice, while Cr+ENanoSi improved the growth of rice under hexavalent chromium stress, with the plant height being 30% higher than that of the Cr group ( Figure 3 a), the chromium concentration in the aboveground part decreased by 70% ( Figure 3 b). This indicates that the method of the present invention can improve the resistance of rice to hexavalent chromium stress.

[0046] Example 3

[0047] In this example, hexavalent chromium stress is taken as an example to compare the effect of the method of the present invention and the traditional matrix application of nano-silicon in enhancing the resistance of rice to heavy metal stress.

[0048] Rice was still selected as the plant material, and the seed germination and seedling growth conditions were the same as in Example 1. Two treatments were set up: Cr+NanoSi group (simulating the application of nano-silicon to the matrix), in which the rice that had not been treated in advance was planted in a 1 / 4 Kimura B nutrient solution containing 50 μM hexavalent chromium, and 1 mM nano-silicon was added (this concentration has been proven to be the best for promoting rice growth and stress resistance); Cr+ENanoSi group (i.e., the method of electrical stimulation using the energizing device of the present invention): a 12V voltage was applied between the positive electrode plate and the negative electrode plate in the energizing chamber 2, and the rice was soaked in the energized nutrient solution containing 10 mM nano-silicon for 30 minutes, and then planted in a 1 / 4 Kimura B nutrient solution containing 50 μM hexavalent chromium. Three pots were used for each treatment, and four rice plants were planted in each pot. One plant was randomly selected from each pot during the measurement, with a total of 3 replicates.

[0049] After 5 days, the plant height of each group of rice was measured. The aboveground part of rice was digested with HNO3, H2O2 and HF. After the volume was fixed to 20 ml with 4% boric acid (to remove residual HF), the Cr concentration was determined by ICP-OES.

[0050] The results showed that the rice growth condition of Cr+ENanoSi group was better than that of Cr+NanoSi group, and the plant height was 8% higher than that of Cr+NanoSi group ( Figure 4 In a), the chromium concentration in the aboveground part was 48% lower than that in the Cr+NanoSi group ( Figure 4 b). This indicates that the method of the present invention performs better than the conventional substrate-applied nano-silicon in a 5-day hexavalent chromium stress experiment.

[0051] Example 4

[0052] In this example, the effect of rapidly establishing a rice root nano-silicon barrier by applying electricity on rice gene expression will be investigated, and the different effects of simple electricity and energized nano-silicon will be distinguished.

[0053] Rice was still selected as the plant material, and the seed germination and seedling growth conditions were the same as in Example 1. Three treatments were set up, namely: CK group: normal 14-day-old rice was soaked in a non-powered device for 30 minutes; E group: 14-day-old rice was powered in a nutrient solution for 30 minutes; ENanoSi group (i.e., a method of electrical stimulation using the power-on device of the present invention): 12V voltage was applied between the positive electrode plate and the negative electrode plate in the power-on chamber 2, and 14-day-old rice was powered in a nutrient solution containing 10mM nano-silicon for 30 minutes. Four seedlings were used as a group, and each treatment contained 3 groups. The buds of the seedlings were cut off, quickly frozen in liquid nitrogen, and stored at -80°C for transcriptome analysis. The total RNA of each sample was extracted using an RNA extraction kit, and the concentration and integrity of the RNA were detected by Agilent 2100 Bioanalyzer (California, USA) and Qubit 2.0 fluorometer (Massachusetts, USA). Subsequently, the mRNA obtained from the sample was synthesized into double-stranded cDNA by reverse transcription. After the double-stranded cDNA was processed and purified, the cDNA library was enriched by PCR. After testing the quality of the library, sequencing was performed using the Illumina Novasek6000 system platform. The sequencing data was then filtered using fastp software version 0.19.3 to obtain clean reads. FPKM (fragments per kilobase of transcript per million map fragments) was used to measure transcript or gene expression levels. Differentially expressed genes (|log2 fold change| ≥ 2, p < 0.05) were identified using DESeq2. A Venn diagram was used to display the common and unique differentially expressed genes between E and ENanoSi. The KEGG database was used to annotate gene pathways and display pathways with significant differences (p < 0.05).

[0054] The results showed that ENanoSi and E affected 363 genes together, E affected 733 genes alone, and ENanoSi affected 567 genes alone ( Figure 5 (a), indicating that the phenomenon of regulating rice gene expression by nano-Si treatment is not only from the power supply, but also from the nano-Si. Compared with E-NanoSi and E-NanoSi, the KEGG enriched pathways with significant differences are mainly concentrated in benzoxazine biosynthesis, circadian rhythm, plant-pathogen interaction, motor protein, glycosylphosphatidylinositol protein synthesis, and α-linolenic acid metabolism ( Figure 5 (b) This further proves that nano-silicon has a strong regulatory effect on rice growth and stress resistance.

[0055] The above-described embodiments are only some preferred solutions of the present invention, but they are not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. An energizing device for establishing a rice nano-silicon defense barrier before transplanting, characterized in that: It comprises a power supply device (1) and a coverless container made of a non-conductive material; The lidless container is divided into three interconnected chambers by two perforated partitions, wherein a plant chamber (3) for placing rice seedlings is located between the two perforated partitions, and two power supply chambers (2) are located on both sides of the plant chamber (3); a nutrient solution containing nano-silicon is stored inside the entire lidless container, and the height of the nutrient solution should be able to immerse the root system of the rice seedlings; The power supply device (1) comprises a battery and positive and negative electrode plates connected to the positive and negative electrodes of the battery respectively. The positive electrode plate and the negative electrode plate are respectively arranged below the surface of the nutrient solution in the two power supply chambers (2) and are used to apply a voltage to both sides of the root system of the rice seedlings immersed in the nutrient solution to induce the roots to form a nano-silicon barrier.

2. The energizing device for establishing a rice nano-silicon defense barrier before transplanting as claimed in claim 1, characterized in that: The positive electrode plate and the negative electrode plate are both made of nickel sheets.

3. The energizing device for establishing a rice nano-silicon defense barrier before transplanting as claimed in claim 1, characterized in that: In the power supply device (1), the positive and negative electrodes of the battery are respectively connected to two metal clips via wires, and the positive electrode plate and the negative electrode plate are respectively conductively clamped and fixed by the metal clips.

4. The energizing device for establishing a rice nano-silicon defense barrier before transplanting as claimed in claim 1, characterized in that: The battery is a storage battery with a supply voltage of 8 to 12V.

5. The energizing device for establishing a rice nano-silicon defense barrier before transplanting as claimed in claim 1, characterized in that: The coverless container is a coverless acrylic plastic box.

6. The energizing device for establishing a rice nano-silicon defense barrier before transplanting as claimed in claim 1, characterized in that: The nutrient solution is 1 / 4 Kimura B nutrient solution.

7. The energizing device for establishing a rice nano-silicon defense barrier before transplanting as claimed in claim 1, characterized in that: The nano silicon concentration in the nutrient solution is 8-12 mM, and the nano silicon particle size is 25-35 nm.

8. A method for establishing a rice nano-silicon defense barrier in front of a rice seedling using the energizing device according to any one of claims 1 to 7, characterized in that: The rice seedlings to be planted are placed in the plant chamber (3) with their leaves facing upward and their roots facing downward, and their roots are kept immersed in the nutrient solution containing nano-silicon; then, the power supply device (1) is used to apply a voltage of 8 to 12 V to both sides of the roots of the rice seedlings immersed in the nutrient solution for electrical stimulation, and the voltage is maintained for at least 30 minutes until a nano-silicon defense barrier is formed at the roots, and then the rice seedlings are taken out.

9. The method according to claim 8, characterized in that The voltage of the electrical stimulation is preferably 12V, and the duration of the electrical stimulation is preferably 30 minutes.

10. A method for growing rice in heavy metal contaminated soil, characterized in that: The rice seedlings to be planted are electrically stimulated according to the method as claimed in claim 8, and then transplanted into heavy metal contaminated soil after a nano-silicon defense barrier is formed at the roots, so as to enhance the rice's ability to resist heavy metal stress.

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