Application of submerged plants pretreated with sodium nitroprusside in water ecological restoration

Abstract

The present invention discloses a method for promoting the growth of submerged plants under the stress of flocculants, and the steps are as follows: Select well-growing submerged plant seedlings. After pruning and cleaning, pre-culture them in 5-15% Hoagland nutrient solution, select seedlings with consistent growth, and obtain the seedlings to be planted after cleaning; Under light-shielded conditions, prepare a sodium nitroprusside pretreatment solution with a concentration of 100-400 μM using a CaCl2 solution; Under constant temperature and light-shielded conditions, completely immerse the seedlings to be planted in the pretreatment solution and pretreat for 3-5 hours, then wash them clean with deionized water and set aside; Transplant the pretreated seedlings into the water body containing flocculants. This method addresses the problem of inhibited growth of submerged plants caused by flocculant pollution in water bodies, improves the tolerance of plants to the toxicity of flocculants, promotes the growth of plants in a flocculant environment, is applicable to the restoration and reconstruction of submerged plants in water bodies with different flocculant accumulation amounts, and has the advantages of simple operation, economic ecology, and remarkable effects.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a divisional application based on application number 202410182221.9, application date February 19, 2024, and invention name: A method for promoting the growth of submerged plants under flocculant stress. Technical Field

[0003] The invention relates to the technical field of water ecological restoration, and in particular to the application of submerged plants pretreated with sodium nitroprusside in water ecological restoration. Background Art

[0004] Eutrophication of water bodies is one of the important problems facing the global water environment. Long-term eutrophication caused by excessive nitrogen and phosphorus pollutants in water bodies will cause the outbreak of blue algae blooms and lead to the decline of water ecological functions. The restoration of eutrophication of water bodies mainly uses physical, chemical and biological methods. Among them, one of the commonly used chemical restoration methods in the early days, the large-scale and frequent use of flocculants (such as aluminum salts, iron salts, polyacrylamide, etc.), has caused secondary pollution to the environment. With the enrichment of flocculants in aquatic ecosystems, certain ecological risks are brought about, which not only pollutes the environment and harms aquatic plants and animals, but also poisons human health. Therefore, controlling the ecological risks of flocculants in aquatic ecosystems is one of the urgent and necessary tasks for water environment protection and governance.

[0005] At present, phytoremediation in bioremediation technology has been widely used as an emerging restoration method due to its advantages such as environmental friendliness, low treatment cost and low energy consumption. With the increasing eutrophication of lakes and polluted water bodies, the aquatic ecosystem has gradually degraded. Therefore, as one of the important components of the ecosystem, the restoration and reconstruction of submerged vegetation plays a key and long-term role in the ecological restoration of eutrophic lakes and water bodies. However, the accumulation of flocculants in aquatic ecosystems can lead to the decline of submerged plant growth, thereby significantly reducing their restoration capacity. Therefore, how to improve the resistance of submerged plants to flocculant toxicity is of urgent and important significance in the restoration of aquatic ecosystems.

[0006] Sodium nitroprusside is often used as an exogenous nitric oxide donor and is applied regularly during the growth of crops and trees to improve their antioxidant capacity, delay leaf senescence, enhance their aluminum stress tolerance, and promote plant growth. Chinese patent CN 113261565B discloses a compound agent for improving crop aluminum tolerance and its application, which relates to the field of plant planting technology and solves the problem that crops are severely poisoned by aluminum stress and have poor aluminum tolerance in the prior art. The key points of its technical solution are: it includes sodium hydrosulfide solution and sodium nitroprusside solution, the volume ratio of sodium hydrosulfide solution to sodium nitroprusside solution is 1:1-4, the concentration of sodium hydrosulfide solution is 2-300 μmol / L, and the concentration of sodium nitroprusside solution is 0.1-1000 μmol / L. The present invention has the advantages of being able to reduce the inhibition of aluminum on crop root elongation growth and improve crop aluminum tolerance. The invention is aimed at trivalent free Al under acidic conditions. 3+ The toxic effect on crops, its toxic mechanism is: toxic free Al 3+ It accumulates on the cell walls of plant root tips, reducing the elasticity and ductility of the cell walls, thereby inhibiting the elongation of root tip cells, causing the growth of plant roots to be suppressed, thereby hindering the plant's absorption of water and nutrients.

[0007] In addition, the invention uses a compound agent containing sodium nitroprusside for long-term leaf spraying during aluminum stress, but this method can easily cause secondary pollution to water bodies, pose certain ecological risks to other aquatic animals, and require certain manpower and material costs.

[0008] Aluminum is amphoteric and presents different forms under different pH conditions. In the past, a large number of studies have shown that the toxic effects of aluminum mainly occur in acidic environments. Under neutral conditions, aluminum is believed to exist mainly in the form of insoluble Al(OH)3 and will not cause toxicity. The pH of lakes and water bodies in my country is generally neutral to weakly alkaline. With the enrichment of flocculants (such as aluminum salts, iron salts, polyacrylamide, etc.) in aquatic ecosystems, it affects the growth of submerged plants. In view of the stress of flocculants on the growth of submerged plants in aquatic ecosystems, it is urgent and important to develop a method to alleviate the toxicity of flocculants to submerged plants with simple operation, wide application range and low economic cost, and to improve the resistance of submerged plants to flocculant toxicity in the restoration of aquatic ecosystems. Summary of the invention

[0009] In order to solve one of the above problems, the present invention provides a method for promoting the growth of submerged plants under flocculant stress, which promotes the ecological restoration of submerged plants. The scheme is simple to operate, has a wide range of applications, low economic cost and significant promotion effect.

[0010] To achieve the above purpose, the technical measures adopted by the present invention are as follows:

[0011] The present invention provides a method for promoting the growth of submerged plants under flocculant stress, comprising the following steps:

[0012] (1) Seedling pre-cultivation: After pruning and cleaning the submerged plant seedlings with good growth, pre-cultivate them in 5-15% Hoagland nutrient solution for 15-20 days, select the seedlings with consistent growth, and wash them to obtain the seedlings to be planted;

[0013] (2) Preparation of pretreatment solution: Prepare a sodium nitroprusside pretreatment solution with a concentration of 100-400 μM using CaCl2 solution under light-proof conditions and place it in a dark place for later use; high concentrations of sodium nitroprusside pretreatment solution significantly inhibit plant root elongation, while low concentrations cannot improve the resistance of submerged plants to flocculant stress;

[0014] (3) Seedling pretreatment: Under constant temperature and light-proof conditions, completely immerse the seedlings to be planted in the pretreatment solution for 3-5 hours, then clean them with deionized water for later use;

[0015] (4) Transplantation: Transplant the pretreated seedlings into water bodies containing flocculants and a pH value of 6.5-7.0 to carry out water ecological restoration.

[0016] Furthermore, in step (2), the concentration of the CaCl2 solution is 0.4-0.6 mM.

[0017] Furthermore, in step (3), the constant temperature condition is 24-26 °C.

[0018] Furthermore, in step (1), the seedlings are trimmed to a height of 10-15 cm. The purpose of this treatment is to ensure the consistency of the initial state of the Vallisneria seedlings in different culture boxes and to more accurately evaluate the toxicity of the aluminum salt flocculant to the growth of Vallisneria.

[0019] Furthermore, in step (1), the seedlings are washed with deionized water to remove the Hoagland nutrient solution attached to the seedlings. Generally, the Vallisneria seedlings are washed 3-4 times with deionized water to completely remove the Hoagland nutrient solution attached to the seedlings.

[0020] Preferably, in step (3), the washed seedlings are soaked in pure water for no more than 6 hours.

[0021] Furthermore, in step (4), the flocculant concentration in the flocculant-stressed water body is higher than 2 mg / L. 2 mg / L is the critical concentration value of the aluminum salt flocculant for inhibiting the growth of Vallisneria in this method.

[0022] In some specific embodiments of the present application, the flocculant is an aluminum salt flocculant, specifically, a polyaluminum chloride flocculant.

[0023] The toxic mechanism of flocculants in water to aquatic plants is as follows: flocculants can reduce the concentration of calcium and phosphorus in water, affect the absorption of phosphorus and calcium, the nutrients required for growth, by plant cells, and chelate with plant growth molecules, thereby inhibiting the growth of submerged plants.

[0024] Beneficial Effects of the Invention

[0025] Compared with the prior art, the present invention has the following beneficial effects: the present invention aims to solve the problem of growth inhibition of Vallisneria or other submerged plants caused by flocculant pollution easily caused by the early stage of water body restoration by chemical reagents, and provides a method for promoting the growth of Vallisneria or other submerged plants.

[0026] The treated seedlings had increased chlorophyll a content in leaves and increased MDA content in roots, showing enhanced tolerance to flocculant toxicity. It is suitable for the restoration and reconstruction of Vallisneria or other submerged plants in water bodies with different flocculant accumulation amounts. It is simple to operate, economical and ecological, and has significant effects.

[0027] Compared with the prior art, the present invention is simple to operate, suitable for water restoration projects with various degrees of pollution, from mild to severe, and has low economic cost. It will not cause external pollution to the water body, improves the survival rate of seedlings of Vallisneria or other submerged plants during the planting adaptation period, promotes the growth of seedlings, and further promotes the reconstruction of submerged plants, so as to improve the stability of the water ecosystem and achieve water purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the incubator of the present invention;

[0029] In the figure: 1. Plants; 2. Planting partitions; 3. Water inlet; 4. Water outlet; 5. Aeration pump; 6. Aeration stone;

[0030] Figure 2 This is a comparative diagram of the growth observation of Vallisneria serrata seedlings under different pre-culture conditions in the present invention;

[0031] Figure 3 The effect of different flocculant concentrations on the chlorophyll a content in Vallisneria sinensis leaves;

[0032] Figure 4 The effect of different flocculant concentrations on the amount of cell death in the roots of Vallisneria lappa;

[0033] Figure 5 Comparison of chlorophyll a content in Vallisneria sinensis leaves under different treatment conditions;

[0034] Figure 6 Comparison of MDA content in roots of Vallisneria salsa under different treatment conditions;

[0035] Figure 7This is a comparative chart of the growth observation of Vallisneria sinensis after different pretreatment times with sodium nitroprusside solution. DETAILED DESCRIPTION

[0036] The following examples are used to demonstrate preferred embodiments of the present invention. It will be appreciated by those skilled in the art that the techniques disclosed in the following examples represent techniques discovered by the inventors that can be used to implement the present invention and therefore can be considered as preferred embodiments of the present invention. However, it will be appreciated by those skilled in the art based on this specification that many modifications may be made to the specific embodiments disclosed herein and still achieve the same or similar results without departing from the spirit or scope of the present invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs, and the materials cited herein and those cited by them are incorporated by reference. Those skilled in the art will recognize or will learn through routine experimentation that there are many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims.

[0038] The technical solution of this patent is further described in detail below in conjunction with specific implementation methods.

[0039] A method for promoting the growth of submerged plants under flocculant stress comprises the following steps:

[0040] (1) Seedling pre-cultivation: After washing the submerged plant seedlings with good growth with clean water, the seedlings are trimmed to a height of 10-15 cm, and then pre-cultivated in 5-15% Hoagland nutrient solution for 15-20 days. Seedlings with consistent growth are selected and rinsed with deionized water to remove the Hoagland nutrient solution attached to the seedlings to obtain seedlings to be planted;

[0041] (2) Preparation of pretreatment solution: Prepare a sodium nitroprusside pretreatment solution with a concentration of 100-400 μM using 0.4-0.6 mM CaCl2 solution under light-proof conditions and place in a dark place for later use;

[0042] (3) Seedling pretreatment: Under constant temperature and light-proof conditions at 24-26°C, completely immerse the seedlings to be planted in the pretreatment solution for 3-5 hours, then clean them with deionized water for later use; the cleaned seedlings can be soaked in pure water for later use, and the soaking time should not exceed 6 hours;

[0043] (4) Transplantation: Transplant the pretreated seedlings into water containing flocculants and a pH value of 6.5-7.0.

[0044] Example 1

[0045] Use as Figure 1The incubator shown includes an incubator body, a black shading plate is arranged around the lower outer side of the incubator, a water inlet and a water outlet are arranged on the body, and aeration is provided to the flocculant water body through an aeration pump and an aeration stone.

[0046] Clean water was added to the incubator, and Vallisneria serrata seedlings with uniform growth were selected and planted in the 10 mm thick black planting partitions in the incubator.

[0047] The culture conditions of the incubator were as follows: the temperature of the constant temperature chamber was 25 °C, the light intensity was 3500 lux, and the light / dark time was 12 / 12 h.

[0048] During the culture process, water was added regularly to ensure that the water level in the culture box was consistent. After about 15 days of culture, the Vallisneria seedlings grown under this condition were collected.

[0049] Example 2

[0050] Use as Figure 1 The incubator shown includes an incubator body, a black shading plate is arranged around the lower outer side of the incubator, a water inlet and a water outlet are arranged on the body, and aeration is provided to the flocculant water body through an aeration pump and an aeration stone.

[0051] Clean water was added to the incubator, and after pre-culturing with 5% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in the 10 mm thick black planting partitions in the incubator.

[0052] The culture conditions of the incubator were as follows: the temperature of the constant temperature chamber was 25 °C, the light intensity was 3500 lux, and the light / dark time was 12 / 12 h.

[0053] During the culture process, water was added regularly to ensure that the water level in the culture box was consistent. After about 15 days of culture, the Vallisneria seedlings grown under this condition were collected.

[0054] Example 3

[0055] Use as Figure 1 The incubator shown includes an incubator body, a black shading plate is arranged around the lower outer side of the incubator, a water inlet and a water outlet are arranged on the body, and aeration is provided to the flocculant water body through an aeration pump and an aeration stone.

[0056] Clean water was added to the incubator, and after pre-culturing with 10% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in the 10 mm thick black planting partitions in the incubator.

[0057] The culture conditions of the incubator were as follows: the temperature of the constant temperature chamber was 25 °C, the light intensity was 3500 lux, and the light / dark time was 12 / 12 h.

[0058] During the culture process, water was added regularly to ensure that the water level in the culture box was consistent. After about 15 days of culture, the Vallisneria seedlings grown under this condition were collected.

[0059] Example 4

[0060] Use as Figure 1 The incubator shown includes an incubator body, a black shading plate is arranged around the lower outer side of the incubator, a water inlet and a water outlet are arranged on the body, and aeration is provided to the flocculant water body through an aeration pump and an aeration stone.

[0061] Clean water was added to the incubator, and after pre-culturing with 20% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in the 10 mm thick black planting partitions in the incubator.

[0062] The culture conditions of the incubator were as follows: the temperature of the constant temperature chamber was 25 °C, the light intensity was 3500 lux, and the light / dark time was 12 / 12 h.

[0063] During the culture process, water was added regularly to ensure that the water level in the culture box was consistent. After about 15 days of culture, the Vallisneria seedlings grown under this condition were collected.

[0064] The growth conditions of Vallisneria seedlings pre-cultured with water, pre-cultured with 5% Hoagland nutrient solution, pre-cultured with 10% Hoagland nutrient solution, and pre-cultured with 20% Hoagland nutrient solution in Examples 1 to 4 were observed and compared. Figure 2 shown.

[0065] The results showed that the leaves of the Vallisneria seedlings pre-cultured with clean water turned yellow and grew the slowest, followed by 5% Hoagland's nutrient solution. The leaves of the Vallisneria plants pre-cultured with 10% Hoagland's nutrient solution were greener and grew most vigorously. However, when the concentration of Hoagland's nutrient solution exceeded 20%, filamentous algae appeared on the leaves of Vallisneria.

[0066] Example 5

[0067] A polyaluminium chloride flocculant water body with a concentration of 1 mg / L was added to the incubator, and the pH value of the water body was 7.0. After pre-cultivation with 10% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in a 10 mm thick black planting partition in the incubator.

[0068] The culture conditions of the incubator were: constant temperature of 25 °C, light intensity of 3500 lux, and light / dark time of 12 / 12 h.

[0069] During the culture process, water was added regularly to ensure that the water level in the culture box was consistent. After about 15 days of culture, the Vallisneria seedlings grown in the water with a flocculant concentration of 1 mg / L were collected.

[0070] Example 6

[0071] A polyaluminium chloride flocculant water with a concentration of 2 mg / L was added to the incubator, and the pH value of the water was 7.0. After pre-cultivation with 10% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in a 10 mm thick black planting partition in the incubator.

[0072] The culture conditions of the incubator were as follows: the temperature of the constant temperature chamber was 25 °C, the light intensity was 3500 lux, and the light / dark time was 12 / 12 h.

[0073] During the culture process, water was added regularly to ensure that the water level in the culture box was consistent. After about 15 days of culture, the Vallisneria seedlings grown in the water with a flocculant concentration of 2 mg / L were collected.

[0074] Example 7

[0075] A polyaluminium chloride flocculant water with a concentration of 3 mg / L was added to the incubator, and the pH value of the water was 7.0. After pre-cultivation with 10% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in a 10 mm thick black planting partition in the incubator.

[0076] The culture conditions of the incubator are: the temperature of the constant temperature chamber is 25 ℃, the light intensity is 3500 lux, and the light / dark time is 12 / 12 hours. During the culture process, water is added regularly to ensure that the water level of the incubator is consistent. After about 15 days of culture, the Vallisneria seedlings grown in the water with a flocculant concentration of 3 mg / L are collected.

[0077] Example 8

[0078] A polyaluminium chloride flocculant water body with a concentration of 4 mg / L was added to the incubator, and the pH value of the water body was 7.0. After pre-cultivation in 10% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in a 10 mm thick black planting partition in the incubator.

[0079] The culture conditions of the incubator are: the temperature of the constant temperature chamber is 25 ℃, the light intensity is 3500 lux, and the light / dark time is 12 / 12 hours. During the culture process, water is added regularly to ensure that the water level of the incubator is consistent. After about 15 days of culture, the Vallisneria seedlings grown in the water with a flocculant concentration of 4 mg / L are collected.

[0080] The chlorophyll a content of the leaves of the Vallisneria serrata seedlings obtained in Examples 4 to 8 was measured. The results are shown in Table 1. Figure 3 As shown; observe the amount of root cell death, the results are as follows Figure 4 shown.

[0081] Table 1 Chlorophyll a content in leaves of Vallisneria ovalis cultured at different flocculant concentrations

[0082]

[0083] The amount of cell death in the plant root system is expressed by the degree of Evans blue staining. The darker the blue color after the root system is stained, the greater the amount of cell death. The results show that 2 mg / L of flocculant can cause cell death in the root system of Vallisneria, and as the concentration increases, the amount of root cell death increases.

[0084] From the above results, it can be seen that the critical concentration value of flocculant to inhibit the growth of Vallisneria is 2 mg / L.

[0085] Example 9

[0086] Add clean water to the incubator. After pre-culturing with 10% Hoagland nutrient solution for 15 days, select Vallisneria seedlings with uniform growth and cleaned and plant them in the 10 mm thick black planting partition in the incubator.

[0087] The culture conditions of the incubator were: constant temperature of 25 °C, light intensity of 3500 lux, and light:dark time ratio of 12 / 12 h.

[0088] During the cultivation process, water was added regularly to ensure that the water level in the incubator was consistent. After about 15 days of cultivation, the Vallisneria seedlings grown in the water were collected.

[0089] Example 10

[0090] A 0.5 mM CaCl2 solution was added to the clean water in the incubator. After pre-culturing in 10% Hoagland nutrient solution for 15 days, Vallisneria seedlings with uniform growth and cleaned were selected and planted in a 10 mm thick black planting partition in the incubator.

[0091] The culture conditions of the incubator were: constant temperature of 35 °C, light intensity of 3500 lux, and light:dark time ratio of 12 / 12 h.

[0092] During the cultivation process, water was added regularly to ensure that the water level in the incubator was consistent. After about 15 days of cultivation, the Vallisneria seedlings grown in the water were collected.

[0093] Embodiment 11

[0094] Under constant temperature and light-proof conditions at 25°C, the cleaned Vallisneria seedlings that had been pre-cultured in 10% Hoagland nutrient solution for 15 days and had uniform growth were completely immersed in a sodium nitroprusside treatment solution prepared with 0.5 mM CaCl2 solution at a concentration of 200 μM for 3 hours, and then cleaned with deionized water for use; the cleaned seedlings were immersed in pure water for no more than 6 hours.

[0095] The incubator was added with flocculant water at a concentration of 2 mg / L. The treated Vallisneria serrata seedlings were planted in a 10 mm thick black planting partition in the incubator.

[0096] The culture conditions of the incubator were as follows: the temperature of the constant temperature chamber was 25 °C, the light intensity was 3500 lux, and the light / dark time was 12 / 12 h.

[0097] During the cultivation process, water was added regularly to ensure that the water level in the incubator was consistent. After about 15 days of cultivation, the Vallisneria seedlings grown in the water were collected.

[0098] Example 12

[0099] Under constant temperature and light-proof conditions at 25°C, the cleaned Vallisneria seedlings that had been pre-cultured in 10% Hoagland nutrient solution for 15 days and had uniform growth were completely immersed in a 200 μM sodium nitroprusside treatment solution prepared with 0.5 mM CaCl2 solution for 5 hours, and then cleaned with deionized water for use; the cleaned seedlings were immersed in pure water for no more than 6 hours.

[0100] The incubator was added with flocculant water at a concentration of 2 mg / L. The treated Vallisneria serrata seedlings were planted in a 10 mm thick black planting partition in the incubator.

[0101] The culture conditions of the incubator were as follows: the temperature of the constant temperature chamber was 25 °C, the light intensity was 3500 lux, and the light / dark time was 12 / 12 h.

[0102] During the cultivation process, water was added regularly to ensure that the water level in the incubator was consistent. After about 15 days of cultivation, the Vallisneria seedlings grown in the water were collected.

[0103] The chlorophyll a content in the leaves and the MDA content in the roots of the Vallisneria truncatula seedlings obtained in Examples 6, 9 and 11 were measured. The results are shown in Tables 2 and Figure 5 , Figure 6 shown.

[0104] Table 2 Chlorophyll a content in leaves and MDA content in roots under different treatment conditions

[0105]

[0106] From the above results, it can be seen that adding CaCl2 to water can provide nutrition for plants. The chlorophyll a content in the leaves of Vallisneria seedlings added with CaCl2 is higher than that of Vallisneria grown under clear water conditions. Compared with Vallisneria seedlings under flocculant stress, the chlorophyll a content in the leaves of Vallisneria seedlings pretreated with 200 μM sodium nitroprusside prepared with 0.5 mM CaCl2 solution increased by 39% and the MDA content in the roots increased by 33% after being cultured in flocculant-stressed water, showing an improved tolerance to flocculant toxicity.

[0107] The Vallisneria seedlings obtained in Example 11 and Example 12 were observed and compared. Figure 7 shown.

[0108] The results showed that under different pretreatment times of sodium nitroprusside, the growth conditions of Vallisneria ovata seedlings were basically the same, with no significant differences.

[0109] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as references separately. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined in the present application.

Claims

1. Application of submerged plants pretreated with sodium nitroprusside in ecological restoration of water bodies stressed by flocculants, characterized in that: Submerged plants are pretreated with sodium nitroprusside and then transplanted into a water body containing polyaluminium chloride flocculant and having a pH value of 6.5-7.0 for water body ecological restoration, wherein the flocculant concentration in the water body is higher than 2 mg / L; The pretreatment of the submerged plants comprises the following steps: (1) Seedling pre-cultivation: After pruning and cleaning the submerged plant seedlings with good growth, pre-cultivate them in 5-15% Hoagland nutrient solution for 15-20 days, select the seedlings with consistent growth, and wash them to obtain the seedlings to be planted; (2) Preparation of pretreatment solution: Prepare a 100-400 μM sodium nitroprusside pretreatment solution with a 0.4-0.6 mM CaCl2 solution in a dark place for later use. (3) Seedling pretreatment: Under constant temperature and light-proof conditions, completely immerse the seedlings to be planted in the pretreatment solution for 3-5 hours, and then rinse them with deionized water to obtain submerged plants pretreated with sodium nitroprusside.

2. The use of the submerged plant pretreated with sodium nitroprusside in the ecological restoration of flocculant-stressed water bodies according to claim 1, characterized in that: In step (3), the constant temperature condition is 24-26°C.

3. The use of the submerged plant pretreated with sodium nitroprusside in the ecological restoration of flocculant-stressed water bodies according to claim 1, characterized in that: In step (3), the cleaned seedlings are placed in pure water and soaked for a period of no more than 6 hours.

4. The use of the submerged plant pretreated with sodium nitroprusside in the ecological restoration of flocculant-stressed water bodies according to claim 1, characterized in that: In step (1), the seedlings are pruned to a height of 10-15 cm.

5. The use of the submerged plant pretreated with sodium nitroprusside in the ecological restoration of flocculant-stressed water bodies according to claim 1, characterized in that: In step (1), the seedlings are washed with deionized water to remove the Hoagland nutrient solution attached to the seedlings.

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