Device and method for inducing silicic acid polymerization of rice roots through electrical stimulation to enhance stress resistance

Abstract

The invention discloses a device and a method for inducing silicic acid polymerization of rice roots through electrical stimulation to enhance stress resistance. By means of the phenomenon that silicic acid polymerization can be accelerated through electrical stimulation, a specific device is designed to induce silicic acid polymerization of the rice roots through electrical stimulation. Based on the device, rice roots can be soaked in an electrified silicic acid-containing nutrient solution, a silicon barrier can be formed at the roots after a certain time, normal growth of rice under heavy metal stress can be maintained, fresh weight can be increased, and the concentration of heavy metal on the overground part can be reduced. The effect of electrically stimulating silicic acid polymerization in a hexavalent chromium stress experiment for 5 days is better than that of applying silicon to a traditional substrate. The method is beneficial to control of harmful effects of heavy metal pollution on crops and guarantee of food safety.

Description

Technical Field

[0001] The present invention belongs to the field of plant stress resistance methods, and more specifically, the present invention relates to a device and method for establishing a stress resistance defense barrier in the root system of rice by utilizing the principle of silicic acid polymerization induced by electrical stimulation. Background Art

[0002] Plants face a variety of abiotic stresses during their growth, such as drought, salinity, extreme temperatures, and heavy metal pollution. These stresses can have a negative impact on the physiological and biochemical processes of plants, leading to reduced photosynthesis, impeded nutrient absorption, and restricted growth and development. In the agricultural field, stress on crops will lead to reduced yields, threatening my country's food security. However, unlike animals, plants cannot actively avoid stress by migrating. They can only cope with these adverse environmental factors through a series of adaptation mechanisms, such as root adjustments, increased antioxidant enzyme activity, and the synthesis of secondary metabolites, thereby improving their own survival and reproduction capabilities. However, the resistance and adaptability of plants themselves are limited, so agricultural methods are needed to artificially improve plant stress resistance.

[0003] In nature, diatoms and some plants can build silicon-based defense barriers outside their cells to protect them from harmful environments. The silicon-based defense barrier on rice can not only improve the mechanical properties of the cell wall, play an important role in resistance to lodging and feeding by herbivorous animals, but also block the absorption of heavy metals and their accumulation in edible parts. However, the methods to help plants build silicon barriers in agricultural practice are very limited, mainly soil application of silicon fertilizers and leaf spraying. Many silicates applied to the soil are fixed in the soil and are not absorbed by the plants. Studies have shown that silicon deposition in the roots is crucial to inhibit the accumulation of toxic substances in the aboveground parts of plants, but silicon sprayed on the leaves is difficult to transport to the roots to help the roots build a defense barrier. Therefore, it is necessary to develop new methods to help rice roots quickly build a silicon defense barrier. Summary of the invention

[0004] The purpose of the present invention is to solve the problem in the prior art that it is difficult to establish a silicon-based defense barrier for rice roots, and based on the principle of electrically stimulating the polymerization of silicate, provide a device and method for electrically stimulating the polymerization of silicate in rice roots to enhance stress resistance.

[0005] The technical solutions specifically adopted in the present invention are as follows:

[0006] In a first aspect, the present invention provides a device for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance, which includes a power supply device, a power supply chamber, and a plant suspension device;

[0007] The power supply chamber stores a nutrient solution containing silicic acid;

[0008] The plant suspension device is used to suspend the rice seedlings above the electrification chamber so that the roots are immersed in the nutrient solution containing silicate;

[0009] The power supply device includes a power supply and positive and negative electrode plates connected to the positive and negative poles of the power supply respectively. The positive electrode plate and the negative electrode plate are arranged below the level of the nutrient solution in the power supply chamber, and are used to apply the voltage required to induce silicon deposition on the roots of rice seedlings immersed in the nutrient solution to both sides of the roots.

[0010] As a preferred embodiment of the first aspect, in the power supply device, 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 power supply are respectively connected to two metal clips through 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 power-on chamber is a lidless acrylic plastic box.

[0013] As a preferred embodiment of the above-mentioned first aspect, the nutrient solution is 1 / 4 Kimura B nutrient solution.

[0014] As a preferred embodiment of the first aspect, the silicate concentration in the nutrient solution is 8-12 mM.

[0015] As a preference for the first aspect above, the silicate concentration in the nutrient solution is preferably 10 mM.

[0016] In a second aspect, the present invention provides a method for inducing silicate polymerization in rice roots to enhance stress resistance by electrical stimulation using the device described in any one of the schemes of the first aspect, wherein the rice seedlings are suspended above an electrification chamber with leaves facing upward and roots facing downward using the plant suspension device, and the roots are immersed in a nutrient solution containing silicate; then, a voltage of 30 to 36 V is applied to both sides of the roots of the rice seedlings immersed in the nutrient solution using the power supply device for electrical stimulation, and the voltage is maintained for at least 30 minutes until a silicon barrier is formed at the roots, and then the rice seedlings are taken out.

[0017] The voltage of the electrical stimulation is preferably 36V.

[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 forming a nano-silicon barrier 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: the current traditional method mainly helps plants establish a silicon defense barrier for their roots by supplying silicon through the matrix, but the silicon applied by the traditional method needs to be absorbed by the plant and then deposited on the cell wall, and the whole process is very slow. In addition, the application of silicon in the matrix also causes fertilizer waste and potential environmental problems, affecting the sustainable development of agriculture. The present invention induces silicate to deposit in the rice root system and form a defense barrier by electrification, and the speed is very fast. Secondly, the present invention only needs to add silicate to the device, and does not need to apply it in large quantities to the environment, which not only improves the fertilizer efficiency but also reduces pollution. In addition, the application of silicon in the matrix requires a lot of manpower and material resources, while the present invention is easy to operate, requires little manpower investment, and has great application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the device for electrically stimulating and inducing silicate polymerization to establish a stress-resistant defense barrier for rice roots in the present invention;

[0022] Figure 2 This is a diagram showing the effect of electrical stimulation on silicate polymerization in an embodiment of the present invention;

[0023] Figure 3 The results of the effect of electrical stimulation on root silicon deposition in the embodiments of the present invention are shown in FIG. (a) is a SEM image of the CK group, (b) is a SEM image of the Si group, (c) is a SEM image of the ESi group, and (d) is the root silicon concentration measurement results of the three groups;

[0024] Figure 4 The results of the electrical stimulation-induced silicon deposition on the growth and chromium content of rice under hexavalent chromium stress in the embodiment of the present invention are shown in FIG; (a) is the plant height under different treatments, and (b) is the chromium concentration in the aboveground part under different treatments;

[0025] Figure 5 1 is a comparison chart of the effects of electrical stimulation-induced silicon deposition and substrate silicon application in the embodiments 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. 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, a device for electrically stimulating and inducing silica polymerization in rice roots to enhance stress resistance is provided, and the device includes three main components, namely, a power supply device 1, a power supply chamber 2, and a plant hanging device 3. The power supply chamber 2 is a watertight container made of a non-conductive material, and the specific material is not limited. In this embodiment, the power supply chamber 2 is a rectangular acrylic plastic box without a cover, and the length, width, and height are 20 cm, 10 cm, and 8 cm, respectively.

[0029] The above-mentioned power-on chamber 2 stores a nutrient solution containing silicate. The formula of the nutrient solution 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 use 1 / 4 Kimura B nutrient solution. In addition, silicate required to establish a silicon barrier for the root system should also be added to the nutrient solution. The silicate concentration in the nutrient solution can be preferably 8 to 12 mM, and more preferably 10 mM.

[0030] The plant hanging device 3 is used to hang the rice seedlings above the power-on chamber 2 so that the roots are immersed in the nutrient solution containing silica. In theory, any mechanism that can achieve the suspension and fixation of the rice seedlings can be used as the plant hanging device 3. In this embodiment, the plant hanging device 3 can be implemented by a cantilever iron frame with a clip, and the leaves of the rice seedlings are clamped and fixed by the clips on the cantilever. After the rice seedlings are hung above the power-on chamber 2, the overall height is adjusted so that the roots are immersed in the nutrient solution.

[0031] The power supply device 1 comprises a power supply and positive and negative electrode plates connected to the positive and negative electrodes of the power supply respectively. The positive electrode plate and the negative electrode plate are arranged below the liquid level of the nutrient solution in the power supply chamber 2, and a certain interval should be maintained between the positive electrode plate and the negative electrode plate to accommodate the root system of the rice seedlings. When the root system of the rice seedlings is immersed in the nutrient solution, the positive electrode plate and the negative electrode plate are located on both sides of the root system respectively. The power supply can apply a certain voltage to the positive electrode plate and the negative electrode plate, and the voltage forms an electrical stimulation to the root system of the rice seedlings immersed in the nutrient solution, thereby inducing silicon deposition at the roots.

[0032] 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 AC or batteries, and its output voltage can preferably be adjusted as required, so as to output a current of a specified voltage. In the present embodiment, the power supply device 1 connects the current output by the power supply to the power-on chamber 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 polymerization of silicate in the nutrient solution, and then deposit on the root surface to form a silicon barrier.

[0033] Therefore, the present invention is based on the above Figure 1 The device shown further provides a method for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance, and the specific method is: using the plant suspension device 3 to suspend the rice seedlings above the power supply chamber 2 with the leaves facing upward and the roots facing downward, and the roots are immersed in the nutrient solution containing silicate; then using the power supply device 1 to apply a voltage of 30 to 36V to both sides of the roots of the rice seedlings immersed in the nutrient solution for electrical stimulation, and after maintaining the silicon barrier at the roots for at least 30 minutes, the rice seedlings are taken out. At this time, the roots of the rice seedlings have formed a layer of 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.

[0034] In the above method, the voltage of electrical stimulation is preferably 36V, and the duration of electrical stimulation is preferably 30 minutes.

[0035] Therefore, when planting rice in heavy metal contaminated soil, the rice seedlings to be planted can be electrically stimulated according to the above method, and then transplanted into heavy metal contaminated soil after a nano-silicon barrier is formed at the roots, so as to enhance the rice's ability to resist heavy metal stress.

[0036] The specific implementation and technical effects of the device and method for electrically induced silicate polymerization to form a root defense barrier of the present invention are described in detail below through several embodiments.

[0037] Example 1

[0038] In this embodiment, through the above Figure 1 The device shown is used to study the effect of different power-on time on the polymerization of silicic acid and to determine the optimal power-on time.

[0039] Considering the safety issues during technology promotion, the voltage used between the positive electrode plate and the negative electrode plate during electrical stimulation is 36V, which is a human safety voltage. Silicic acid is prepared from sodium silicate by hydrogen-type ion exchange resin. Since silicic acid will slowly spontaneously polymerize after exceeding the concentration of 2mM, all experimental silicic acid is prepared and used immediately. In order to test the effect of power-on time on silicic acid polymerization, in the absence of rice seedlings, 1 / 4 Kimura B nutrient solution containing 10mM silicic acid in the power-on chamber 2 is powered by 36V (the voltage between the positive electrode plate and the negative electrode plate in the power-on chamber 2 is 36V), and 1ml of solution is taken for testing at 0, 10, 20, 30min, and 40min after power-on, with 3 replicates for each treatment. Unpolymerized silicic acid can react with molybdenum reagent to form silicomolybdic acid, while polymerized silicic acid cannot. Therefore, based on this principle, the concentration of unpolymerized silicic acid in the solution is determined using molybdenum blue photometry.

[0040] The results showed that applying 36V electricity to silicate with an initial concentration of 10mM promoted the polymerization of silicate. The concentration of unpolymerized silicate in the solution decreased rapidly in the first 30 minutes as the power-on time increased, and then decreased slowly after 30 minutes. The concentration of unpolymerized silicate was around 4mM ( Figure 2 ). Therefore, a duration of 30 min was selected for electrifying the rice seedlings.

[0041] Example 2

[0042] In this embodiment, based on the optimal power-on time determined in Embodiment 1, Figure 1 The device shown induces silicic acid polymerization in rice roots and detects the formed silicon barrier.

[0043] Rice seeds (Oryza sativa L.cv. Nipponbare) were sterilized with 10% hydrogen peroxide for 10 minutes, washed three times with deionized water, placed on damp 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), which was changed 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. A 14-day-old rice seedling was suspended above the electrification chamber 2 by a plant suspension device 3, and the roots were immersed in the nutrient solution to carry out an electrical stimulation experiment.

[0044] In this embodiment, three treatments are provided, and the composition of the nutrient solution in the electrification chamber 2 and the electrical stimulation method are different, specifically: the control group (CK) is to immerse the rice roots in the nutrient solution (without silica) for 30 minutes, the silicon treatment group (Si) is to immerse the rice roots in the nutrient solution containing 10mM silica without electricity for 30 minutes, and the electrical stimulation group (ESi) is to immerse the rice roots in the nutrient solution containing 10mM silica, and pass 36V electricity to the nutrient solution (the voltage between the positive electrode plate and the negative electrode plate in the electrification chamber 2 is 36V) for 30 minutes. Then, the root surface is cleaned with 10% EDTA solution and deionized water. The fresh root segments of a part of the seedlings in each group are cut off, immediately attached to the carbon glue, and freeze-dried with a freeze dryer. Before the test, the roots are sprayed with gold. The silicon deposition on the surface of the rice roots with different treatments is observed using SEM-EDS, and photos are taken. Another part of the roots are dried and then digested with HNO3, H2O2 and HF. After the volume was adjusted to 20 ml using 4% boric acid (to remove residual HF), the Si element concentration was determined by ICP-OES. Each treatment contained three biological replicates.

[0045] The results of SEM showed that the surface of rice roots not soaked in silicic acid was very smooth, with no obvious silicon particle deposition ( Figure 3 However, a large amount of silicon particles were deposited on the surface of rice roots after being electrified in silicate for 30 minutes, much more than that on the surface of rice roots soaked in silicate for 30 minutes ( Figure 3 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 Si group was 44% higher than that of the CK group, and the root silicon concentration of the ESi group was 262% higher than that of the Si group ( Figure 3 (d) This indicates that the electrical stimulation method of the present invention can quickly establish a silicon barrier in the rice root system.

[0046] Example 3

[0047] Example 2 has demonstrated the effect of the electrical stimulation method of the present invention on inducing the deposition of silica in the rice root system, but the effect of this method on the stress resistance of rice has not been evaluated. In this example, taking hexavalent chromium stress as an example, we continue to Figure 1 The device shown is used to verify the effect of electrical stimulation inducing root silicon deposition to improve rice stress resistance.

[0048] Rice was still selected as the plant material, and the seed germination and seedling growth conditions were the same as those in Example 2. Three treatments were set in this example: 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+Esi group (i.e., the method of using the device of the present invention for electrical stimulation): rice was soaked in a nutrient solution containing 10 mM silicic acid with 36V electricity (the voltage between the positive electrode plate and the negative electrode plate in the power-on chamber 2 was 36V) 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.

[0049] After 5 days, the fresh weight of rice in each group 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 hexavalent chromium stress inhibited the normal growth of rice, while Cr+ESi improved the growth of rice under hexavalent chromium stress, and the fresh weight was 32% higher than that of the Cr group ( Figure 4 In a), the chromium concentration in the aboveground part decreased by 64% ( Figure 4 b). This indicates that the method of the present invention can improve the resistance of rice to hexavalent chromium stress.

[0051] Example 4

[0052] In this example, hexavalent chromium stress is taken as an example to compare the effects of the method of the present invention and traditional substrate silicon application in enhancing the stress resistance of rice.

[0053] Rice was still selected as plant material, and the seed germination and seedling growth conditions were the same as those in Example 2. Two treatments were set in this example: Cr+Si group (simulated matrix silicon application): 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 silicic acid was added (this concentration has been proven to be the best for promoting rice growth and stress resistance); Cr+ESi group (i.e., the method of using the device of the present invention for electrical stimulation): rice was soaked in a nutrient solution containing 10 mM silicic acid with 36V electricity (the voltage between the positive electrode plate and the negative electrode plate in the power-on chamber 2 was 36V) 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.

[0054] After 5 days, the fresh weight of rice in each group 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.

[0055] The results showed that the rice growth in the Cr+ESi group was better than that in the Cr+Si group, and the fresh weight was 15% higher than that in the Cr+Si group ( Figure 5 In a), the chromium concentration in the aboveground part was 44% lower than that in the Cr+Si group ( Figure 5 b). This indicates that the device and method of the present invention outperformed the traditional substrate silicon application in the 5-day hexavalent chromium stress experiment.

[0056] 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. A device for electrically stimulating the induction of silicate polymerization in rice roots to enhance stress resistance, characterized in that: It comprises a power supply device (1), a power supply chamber (2) and a plant hanging device (3); The power supply chamber (2) stores a nutrient solution containing silicic acid; The plant hanging device (3) is used to hang the rice seedlings above the electrification chamber (2) so that the root system is immersed in the nutrient solution containing silicate; The power supply device (1) comprises a power supply and positive and negative electrode plates connected to the positive and negative electrodes of the power supply respectively. The positive electrode plate and the negative electrode plate are arranged below the level of the nutrient solution in the power supply chamber (2) at intervals, and are used to apply the voltage required to induce silicon deposition at the roots to both sides of the root system of the rice seedlings immersed in the nutrient solution.

2. The device for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance as claimed in claim 1, characterized in that: In the power supply device (1), both the positive electrode plate and the negative electrode plate are made of nickel sheets.

3. The device for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance as claimed in claim 1, characterized in that: In the power supply device (1), the positive and negative electrodes of the power supply 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 device for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance as claimed in claim 1, characterized in that: The power supply chamber (2) is a plastic box made of acrylic material without a cover.

5. The device for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance as claimed in claim 1, characterized in that: The nutrient solution is 1 / 4 Kimura B nutrient solution.

6. The device for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance as claimed in claim 1, characterized in that: The silicate concentration in the nutrient solution is 8-12 mM.

7. The device for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance as claimed in claim 1, characterized in that: The silicic acid concentration in the nutrient solution is preferably 10 mM.

8. A method for inducing silicate polymerization in rice roots to enhance stress resistance by using electrical stimulation of the device according to any one of claims 1 to 7, characterized in that: The plant suspension device (3) is used to suspend rice seedlings above a power supply chamber (2) with leaves facing upward and roots facing downward, and the roots are immersed in a nutrient solution containing silica. Then, the power supply device (1) is used to apply a voltage of 30 to 36 V to both sides of the roots of the rice seedlings immersed in the nutrient solution for electrical stimulation. After the voltage is maintained for at least 30 minutes to form a silicon barrier at the roots, the rice seedlings are taken out.

9. The method according to claim 8, characterized in that The voltage of the electrical stimulation is preferably 36V, 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 nano-silicon barriers are formed at the roots, so as to enhance the rice's ability to resist heavy metal stress.

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