Device and method for electrically stimulating rice root silicic acid polymerization to enhance stress resistance

Abstract

The present invention discloses a device and method for electrically stimulating and inducing silicate polymerization in rice roots to enhance stress resistance. The present invention utilizes the phenomenon that electrical stimulation accelerates silicate polymerization and designs a specific device to achieve electrically stimulating and inducing silicate polymerization in rice roots. Based on this device, the rice root system can be immersed in an electrified silicate-containing nutrient solution. After a certain period of time, a silicon barrier can be formed at the root, 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. In a 5-day hexavalent chromium stress experiment, the effect of electrically stimulating silicate polymerization was better than that of traditional substrate silicon application. The present invention helps to control the harmful effects of heavy metal pollution on crops and ensure food security.

Description

Technical Field

[0001] The present invention belongs to the field of plant stress resistance methods, and more specifically, relates to a device and method for establishing a stress resistance defense barrier in the rice root system 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 negatively impact the physiological and biochemical processes of plants, leading to reduced photosynthesis, impeded nutrient absorption, and restricted growth and development. In the agricultural sector, 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 adaptive mechanisms, such as root adjustments, increased antioxidant enzyme activity, and the synthesis of secondary metabolites, thereby improving their own survival and reproductive capacity. 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 not only improves the mechanical properties of the cell wall, playing an important role in resistance to lodging and herbivorous animals, but also blocks the absorption of heavy metals and their accumulation in edible parts. However, in agricultural practice, the methods to help plants build silicon barriers are very limited, mainly soil application of silicon fertilizers and foliar spraying. Much of the silicate applied to the soil is fixed in the soil and not absorbed by the plant. Studies have shown that silicon deposition in the roots is crucial for inhibiting 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 electrical stimulation-induced silica polymerization, provide a device and method for electrically stimulating and inducing silica polymerization 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, comprising a power supply device, an electrification chamber, and a plant suspension device;

[0007] A nutrient solution containing silicic acid is stored in the power supply chamber;

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

[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 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 power-on chamber is made of an uncovered acrylic plastic box.

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

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

[0015] As a preference of the first aspect above, the silicic acid 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 using electrical stimulation from the device described in any of the schemes of the first aspect above. The method comprises using the plant suspension device to suspend rice seedlings above an electrified chamber with their leaves facing upward and their roots facing downward, and immersing the roots in a nutrient solution containing silicate. The power supply device is then 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. The voltage is maintained for at least 30 minutes to form a silica barrier at the roots, and then the rice seedlings are removed.

[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 growing 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 to enhance the rice's resistance to 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 in their root system by supplying silicon through the matrix. However, the silicon applied by the traditional method needs to be absorbed by the plant and then deposited in 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, on the other hand, induces silicate to deposit in the rice root system and form a defense barrier by applying electricity, 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 huge application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 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 graph showing the effect of electrical stimulation on silicic acid polymerization in an embodiment of the present invention;

[0023] Figure 3 Figures show the effect of electrical stimulation on root silicon deposition in an embodiment of the present invention; (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 Graph showing the effect of electrical stimulation-induced silicon deposition on rice growth and chromium content under hexavalent chromium stress in an embodiment of the present invention; (a) shows plant height under different treatments, and (b) shows chromium concentration in the aboveground part under different treatments;

[0025] Figure 5 Graph comparing the effects of electrical stimulation-induced silicon deposition and substrate silicon application in an 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. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to 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 than 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 the various embodiments of the present invention can be combined accordingly without conflicting with each other.

[0027] In the description of the present invention, it should be understood that when an element is considered to be "connected" to another element, it can 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 is provided for electrically stimulating the induction of silicate polymerization in rice roots to enhance stress resistance. The device comprises three main components: a power supply 1, an electrification chamber 2, and a plant suspension device 3. The electrification chamber 2 is a watertight container made of a non-conductive material, the specific material being of no particular limitation. In this embodiment, the electrification chamber 2 is a lidless rectangular acrylic plastic box with a length, width, and height of 20 cm, 10 cm, and 8 cm, respectively.

[0029] The power chamber 2 contains a nutrient solution containing silicic acid. The nutrient solution's formulation should meet the rice's growth requirements, but the specific ingredients can be adjusted based on actual needs. In an embodiment of the present invention, the nutrient solution can be 1 / 4 Kimura B nutrient solution. Furthermore, the nutrient solution should also contain silicic acid, which is required to establish a silicon barrier for the root system. The silicic acid concentration in the nutrient solution can preferably be 8-12 mM, more preferably 10 mM.

[0030] The plant suspension device 3 is used to suspend rice seedlings above the power supply chamber 2, immersing their roots in the silicic acid-containing nutrient solution. Theoretically, any mechanism capable of suspending and securing rice seedlings can be used as the plant suspension device 3. In this embodiment, the plant suspension device 3 is implemented as a cantilevered iron stand with clamps. The leaves of the rice seedlings are clamped and secured by the clamps on the cantilevered arms. After the rice seedlings are suspended above the power supply chamber 2, the overall height is adjusted to ensure 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 terminals of the power supply, respectively. The positive and negative electrode plates are positioned below the nutrient solution level within the power supply chamber 2, with a certain distance between them to accommodate the roots of the rice seedlings. When the roots of the rice seedlings are immersed in the nutrient solution, the positive and negative electrode plates are positioned on either side of the roots. The power supply applies a voltage to the positive and negative electrode plates, which electrically stimulates the roots of the rice seedlings submerged in the nutrient solution, thereby inducing silicon deposition on 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 poles of the power supply are connected to two metal clips through wires, and the positive electrode plate and the negative electrode plate are conductively clamped and fixed by the metal clips. The introduction of the metal clips is to facilitate the replacement and fixation of the nickel sheets. In theory, it is also feasible to directly connect the wires to the metal clips. The power supply device 1 can be powered by AC power or batteries, and its output voltage can preferably be adjusted as needed, so that it can output 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 roots will accelerate the polymerization of silica in the nutrient solution, which will then be deposited 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 the induction of silicate polymerization in rice roots to enhance stress resistance. Specifically, the method comprises: using the plant suspension device 3, suspending a rice seedling with its leaves facing upward and its roots facing downward above the power supply chamber 2, with the roots immersed in a nutrient solution containing silicate. Then, using the power supply device 1, a voltage of 30 to 36 V is applied to both sides of the rice seedling's root system, which is immersed in the nutrient solution, to electrically stimulate the seedling. This voltage is maintained for at least 30 minutes until a silica barrier forms on the root system, and the seedling is removed. At this point, the rice seedling's roots have formed a silica barrier, which helps maintain normal growth under heavy metal stress, increases fresh weight, and reduces heavy metal concentrations in the aboveground part of the rice.

[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 forming a nano-silicon barrier at the roots 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 silica 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 times on the polymerization of silicic acid and to determine the optimal power-on time.

[0039] Taking into account safety issues during technology promotion, the voltage used between the positive electrode plate and the negative electrode plate during electrical stimulation is 36V, a safe voltage for the human body. Silicic acid is prepared by passing sodium silicate through a hydrogen-type ion exchange resin. Since silicic acid will slowly and spontaneously polymerize after exceeding a concentration of 2mM, the silicic acid in all experiments was prepared and used immediately. In order to test the effect of power-on time on silicic acid polymerization, in the absence of rice seedlings, 36V electricity was applied to 1 / 4 Kimura B nutrient solution containing 10mM silicic acid inside the power-on chamber 2 (the voltage between the positive electrode plate and the negative electrode plate in the power-on chamber 2 was 36V), and 1ml of the solution was taken for testing at 0, 10, 20, 30 minutes, and 40 minutes 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 was determined using molybdenum blue photometry.

[0040] The results showed that applying 36V to a solution of 10mM silicate at an initial concentration promoted its polymerization. The concentration of unpolymerized silicate in the solution decreased rapidly with the extension of the power supply time in the first 30 minutes, 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 Example 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 in the dark at 30°C for five days. 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 periods were 14 and 10 hours, respectively. Fourteen-day-old rice seedlings were suspended above the electrification chamber 2 using a plant suspension device 3, with their roots immersed in the nutrient solution, for electrical stimulation experiments.

[0044] This example employed three treatments, varying the composition of the nutrient solution within the electrified chamber 2 and the method of electrical stimulation. Specifically, the control group (CK) immersed the rice roots in a nutrient solution (containing no silicic acid) for 30 minutes; the silicon-treated group (Si) immersed the rice roots in a non-electrified nutrient solution containing 10 mM silicic acid for 30 minutes; and the electrically stimulated group (ESi) immersed the rice roots in a nutrient solution containing 10 mM silicic acid, with a 36V voltage applied to the solution (the voltage between the positive and negative electrodes within the electrified chamber 2 was 36V) for 30 minutes. The root surfaces were then cleaned with 10% EDTA solution and deionized water. Fresh root segments from a portion of the seedlings in each group were excised, immediately attached to carbon glue, and freeze-dried using a freeze dryer. Prior to testing, the roots were sprayed with gold. Silicon deposition on the surface of the rice roots from the different treatments was observed and photographed using SEM-EDS. Other roots were dried and then digested using HNO3, H2O2, and HF. After the volume was adjusted 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.

[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 silicic acid for 30 minutes, which was much more than that of rice roots after being soaked in silicic acid 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 silicon concentration in the roots of the Si group was 44% higher than that of the CK group, and the silicon concentration in the roots 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 silicate 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 on 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 in Example 2. Three treatments were set up 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 50μM 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 10mM silicic acid with 36V electricity (the voltage between the positive electrode plate and the negative electrode plate in the power chamber 2 was 36V) for 30 minutes, and then planted in a 1 / 4 Kimura B nutrient solution containing 50μM 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 each rice group was measured. The aboveground rice was digested with HNO3, H2O2, and HF. The volume was adjusted to 20 ml with 4% boric acid (to remove residual HF), and 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 used as an example to compare the effects of the method of the present invention and traditional substrate silicon application in enhancing rice stress resistance.

[0053] Rice was again selected as the plant material, and the seed germination and seedling growth conditions were the same as in Example 2. This example provided two treatments: the Cr+Si group (simulating substrate silicon application): untreated rice was planted in a 1 / 4 Kimura B nutrient solution containing 50 μM hexavalent chromium and 1 mM silicic acid (this concentration has been shown to be optimal for promoting rice growth and stress resistance); the Cr+ESi group (i.e., the method of electrical stimulation using the device of the present invention): 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 electrification 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 for the measurement, with a total of three replicates.

[0054] After 5 days, the fresh weight of each rice group was measured. The aboveground rice was digested with HNO3, H2O2, and HF. The volume was adjusted to 20 ml with 4% boric acid (to remove residual HF), and 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 embodiments described above are merely some preferred embodiments of the present invention and are not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A device for electrically inducing 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 roots are 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 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 (2) at intervals, 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 root system.

2. The device for electrically inducing silicate polymerization in rice roots to enhance stress resistance according to 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 inducing silicate polymerization in rice roots to enhance stress resistance according to claim 1, characterized in that: In the power supply device (1), the positive and negative electrodes of the power supply are connected to two metal clips via wires, and the positive electrode plate and the negative electrode plate are conductively clamped and fixed by the metal clips.

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

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

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

8. A method for enhancing stress resistance by inducing silicate polymerization in rice roots using electrical stimulation of the device according to any one of claims 1 to 7, characterized in that: The rice seedlings are suspended above the power supply chamber (2) with their leaves facing upward and their roots facing downward using the plant suspension device (3), and the roots are immersed in a nutrient solution containing silica. The power supply device (1) then applies 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. The voltage is maintained for at least 30 minutes until a silicon barrier is formed on the roots, and the rice seedlings are then removed.

9. The method according to claim 8, wherein 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 on the roots, so as to enhance the rice's ability to resist heavy metal stress.

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