Method for improving transplanting survival rate of saplings in hydro-fluctuation zone of hydropower station reservoir area in dry-hot valley area

Abstract

The invention relates to the technical field of ecological restoration, in particular to a method for improving the transplanting survival rate of saplings in a hydro-fluctuation belt of a hydropower station reservoir area in a dry-hot valley area, which comprises the following steps: mixing a composite slow-release fungicide composition, saplings and seedling raising soil, putting the mixture into planting pits, and maintaining; the composition comprises the following raw materials: arbuscular mycorrhizal fungus powder, plant growth-promoting rhizobacteria, an alginate aqueous solution, a salicylate aqueous solution and a calcium chloride solution. The preparation method of the composition comprises the following steps: mixing the arbuscular mycorrhizal fungi, the plant growth-promoting rhizobacteria and the salicylate aqueous solution to obtain a mixture; dropwise adding the mixture into an alginate aqueous solution to form a mixed solution; and mixing the mixed solution with a calcium chloride aqueous solution, and curing to obtain the composite slow-release fungicide composition. The composite slow-release fungicide composition is mixed with saplings, so that the survival rate of the saplings is increased, and the ecological restoration rate of a hydropower station reservoir area in a dry and hot valley area is increased.

Description

Technical Field

[0001] The invention relates to the technical field of ecological restoration, and in particular to a method for improving the survival rate of transplanting saplings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region. Background Art

[0002] With the continuous increase of the world's population and the continuous improvement of productivity, the demand for energy is getting higher and higher. However, the traditional fossil fuels are gradually in short supply and the pollution to the environment is getting worse and worse. Therefore, green hydropower stations have become a good choice for people. The dry and hot valley area is a famous agricultural area in southwest China that produces a lot of fruits. However, due to the rugged terrain and steep slopes, the ecological environment has deteriorated greatly. However, we can make full use of the water resources of this land to develop hydropower stations. Therefore, the importance of slope ecological restoration technology in the dry and hot valley area to the construction of green hydropower stations cannot be ignored.

[0003] Dry hot valley refers to high temperature and low humidity valley area, mostly distributed in tropical or subtropical areas. The region is rich in light and heat resources, hot climate and little rain, serious soil erosion, very fragile ecology, cold, early, wind, insects, grass, fire and other natural disasters are particularly prominent. my country's dry hot valleys are mainly distributed in Panzhihua, Sichuan, Yunnan and Guizhou along the Jinsha River, Yuanjiang River, Nujiang River and Nanpan River. The Yunnan-Guizhou Plateau has gentle mountains and thick soil, but sparse vegetation and forest coverage of less than 5%. Looking around, it is all bare red soil.

[0004] After the completion and operation of the hydropower station, the water level in the reservoir area rises and falls periodically to form a water-land transition zone that is alternately submerged and exposed, which is the drawdown zone. After the formation of the drawdown zone, the original vegetation is destroyed, soil erosion is aggravated, and it is easy to cause the collapse of the reservoir bank, resulting in the deterioration of the ecological environment in the area and threatening the ecological and environmental safety of the reservoir area. The vegetation in the drawdown zone also has the functions of stabilizing the reservoir bank and intercepting non-point source pollution. Therefore, it is of great practical significance to carry out vegetation ecological restoration in the drawdown zone reservoir area. However, the water-heat contradiction in the dry and hot valley area is prominent, the annual evaporation is 3-6 times the annual precipitation, and drought and water shortage frequently occur in the rainy season. The evaporation in the dry season is 10-27 times the rainfall, which also makes it difficult to carry out vegetation restoration in the drawdown zone in this area.

[0005] Previous studies have shown that mycorrhizal fungi infection can significantly improve the physiological characteristics of plants' resistance to flooding and drought. Plant rhizosphere growth-promoting bacteria can improve the survival of plants in extreme stress environments such as drought and hypoxia. However, there is still a lack of relevant technical support for how to improve the infection efficiency and growth of mycorrhizal fungi in the roots of vegetation in the drawdown zone under drought and flooding habitats, and further promote the survival rate of transplanted plants in stress habitats, which will be detrimental to the ecological restoration of vegetation in the drawdown zone and the stability of the reservoir bank.

[0006] Therefore, it is necessary to develop a method and technology for transplanting vegetation in the drawdown zone based on improving the efficiency of microbial inoculation and infection of plant roots, so as to improve the survival rate of vegetation transplantation in the drawdown zone and the success rate of ecological restoration. Summary of the invention

[0007] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry and hot valley area, so as to improve the survival rate of transplanted vegetation in the drawdown zone and the success rate of ecological restoration.

[0008] To achieve the above objectives and other related objectives, the present invention is achieved through the following technical solutions.

[0009] The first aspect of the present invention is to provide a composite sustained-release bacterial agent composition, which comprises the following raw materials in parts by weight: 20-30 parts of arbuscular mycorrhizal fungus powder, 15-20 parts of plant rhizosphere growth-promoting bacteria, 20-30 parts of alginate aqueous solution, 5-10 parts of salicylate aqueous solution, and 10-20 parts of calcium chloride solution.

[0010] The second aspect of the present invention is to provide a method for preparing the composite sustained-release bacterial agent composition according to the above, comprising the following steps:

[0011] S1, mixing arbuscular mycorrhizal fungi, plant rhizosphere growth-promoting bacteria, and a salicylate aqueous solution to obtain a mixture;

[0012] S2, dropping the mixture obtained in step S1 into an aqueous alginate solution to form a mixed solution;

[0013] S3, mixing the mixed solution obtained in step S2 with a calcium chloride aqueous solution, and solidifying the mixture to obtain a composite sustained-release bacterial agent composition.

[0014] The third aspect of the present invention provides a method for improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region, comprising the following steps: mixing the above-mentioned composite slow-release bacterial agent composition or the composite slow-release bacterial agent composition obtained by the above-mentioned preparation method, seedlings, and seedling soil, placing them in a planting pit, and maintaining them.

[0015] As described above, the method of the present invention for improving the survival rate of transplanting seedlings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region has the following beneficial effects:

[0016] (1) The arbuscular mycorrhizal fungi added in the present invention help to infect the plant root system, thereby improving the capture of oxygen by the mycorrhizal symbiont in a flooded state and the capture of water in a dry state. At the same time, it also helps to form a microbial hotspot area in the rhizosphere of the plant, which is conducive to the aggregation and reproduction of microorganisms, and further improves the survival rate of vegetation in the drawdown zone.

[0017] (2) The present invention can increase the abundance and diversity of rhizosphere microorganisms, thereby improving the stress resistance of plants under flooding and drought conditions and increasing plant survival rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a distribution diagram of the survival rates of different seedlings transplanted in the water-fall zone of this embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose of the invention, technical solutions and beneficial technical effects of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. People familiar with this technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0020] The first aspect of the present invention is to provide a composite sustained-release bacterial agent composition, which comprises the following raw materials in parts by weight: 20-30 parts of arbuscular mycorrhizal fungus powder, 15-20 parts of plant rhizosphere growth-promoting bacteria, 20-30 parts of alginate aqueous solution, 5-10 parts of salicylate aqueous solution, and 10-20 parts of calcium chloride solution.

[0021] The present invention mixes arbuscular mycorrhizal fungal agents, plant rhizosphere growth-promoting bacteria and sodium salicylate according to the mass percentage, drips the mixed agent into a sodium alginate solution to form a mixed solution, and then mixes the mixed solution into a curing agent calcium chloride to form a composite sustained-release bacterial agent capsule.

[0022] In some specific embodiments of the present invention, the composition comprises the following raw materials in parts by weight: 20-25 parts of arbuscular mycorrhizal fungi powder, 15-18 parts of plant rhizosphere growth-promoting bacteria, 20-25 parts of alginate aqueous solution, 5-8 parts of salicylate aqueous solution, and 10-15 parts of calcium chloride solution.

[0023] In some specific embodiments of the present invention, the composition comprises the following raw materials in parts by weight: 25-30 parts of arbuscular mycorrhizal fungi powder, 18-20 parts of plant rhizosphere growth-promoting bacteria, 25-30 parts of alginate aqueous solution, 8-10 parts of salicylate aqueous solution, and 15-20 parts of calcium chloride solution.

[0024] In some specific embodiments of the present invention, the composition comprises the following raw materials in parts by weight: 20 parts of arbuscular mycorrhizal fungi powder, 15 parts of plant rhizosphere growth-promoting bacteria, 20 parts of alginate aqueous solution, 5 parts of salicylate aqueous solution, and 10 parts of calcium chloride solution.

[0025] In some specific embodiments of the present invention, the composition comprises the following raw materials in parts by weight: 25 parts of arbuscular mycorrhizal fungi powder, 18 parts of plant rhizosphere growth-promoting bacteria, 25 parts of alginate aqueous solution, 8 parts of salicylate aqueous solution, and 15 parts of calcium chloride solution.

[0026] In some specific embodiments of the present invention, the composition comprises the following raw materials in parts by weight: 30 parts of arbuscular mycorrhizal fungi powder, 20 parts of plant rhizosphere growth-promoting bacteria, 30 parts of alginate aqueous solution, 10 parts of salicylate aqueous solution, and 20 parts of calcium chloride solution.

[0027] In some embodiments of the present invention, the strains of the arbuscular mycorrhizal fungi are selected from one or more of Glomus endoradici, Glomus mosesi, Glomus terrestrial, and Glomus juvenile; the present invention has no special limitation on the source of the arbuscular mycorrhizal fungi, and commercially available products of arbuscular mycorrhizal fungi well known to those skilled in the art can be used. Specifically, the strains of the arbuscular mycorrhizal fungi are all from the "Arbuscular Mycorrhizal Fungi Germplasm Resource Bank" of Beijing Academy of Agriculture and Forestry Sciences; at the same time, the strains are propagated using clover; the present invention has no special limitation on the propagation method of the strains, and the propagation method frequently used by those skilled in the art can be used. That is, after the arbuscular mycorrhizal fungi are propagated using clover, the root system of the clover (including strain spores and hyphae) is powdered to form the arbuscular mycorrhizal agent.

[0028] In some embodiments of the present invention, the arbuscular mycorrhizal fungal agent is composed of fungal spores, hyphae, and plant roots that coexist with the fungal species; the plants that coexist with the fungal species can be terrestrial herbs, etc. For example, clover. The species of arbuscular mycorrhizal fungi in the composite agent match the species of transplanted plants that can be infected by the fungal species of the arbuscular mycorrhizal fungal agent; the type and quantity of fungal spores can not only ensure the success rate of fungal spores infecting plants, but also maintain a low workload of expansion and low manufacturing cost. The infection of plant roots by arbuscular mycorrhizal fungi helps to improve the capture of oxygen by mycorrhizal symbionts in a flooded state and the capture of water in a drought state. At the same time, it also helps to form a microbial hotspot area in the rhizosphere of plants, which is conducive to the aggregation and reproduction of microorganisms, and further improves the survival rate of vegetation in the drawdown zone.

[0029] In some embodiments of the present invention, the number of spores of the arbuscular mycorrhizal fungi is 50-100 / g. Specifically, the number may be 50-70 / g, 70-85 / g, 85-100 / g; typically but not limited to, for example, 50 / g, 70 / g, 85 / g, 100 / g.

[0030] In some embodiments of the present invention, the mass percentage concentration of the calcium chloride aqueous solution is 2-5%; specifically, the mass percentage concentration can be 2-3%, 3-5%; typically but not limiting, for example, 2%, 3%, 5%. The present invention has no special restrictions on the source of the calcium chloride aqueous solution, and commercially available products of calcium chloride aqueous solutions well known to those skilled in the art can be used.

[0031] In some embodiments of the present invention, the alginate aqueous solution is selected from a sodium alginate aqueous solution or a potassium alginate aqueous solution; preferably, the alginate aqueous solution is a sodium alginate aqueous solution. The present invention has no particular limitation on the source of the sodium alginate aqueous solution, and a commercially available sodium alginate aqueous solution well known to those skilled in the art can be used. The mass percentage concentration of the alginate aqueous solution is 1.5-3%.

[0032] In some embodiments of the present invention, the salicylate aqueous solution is selected from a sodium salicylate aqueous solution or a potassium salicylate aqueous solution; preferably, the salicylate aqueous solution is a sodium salicylate aqueous solution. The present invention does not specifically limit the source of the sodium salicylate aqueous solution, and a commercially available product of a sodium salicylate aqueous solution well known to those skilled in the art can be used. The concentration of the salicylate aqueous solution is 100-150ppm. Specifically, the concentration can be 100-120ppm, 120-135ppm, 135-150ppm, typically but not limiting, for example, 100ppm, 120ppm, 135ppm, 150ppm.

[0033] In some embodiments of the present invention, the plant rhizosphere growth-promoting bacteria are selected from one or more of Bacillus subtilis, Pseudomonas and Serratia. The present invention has no particular limitation on the source of the plant rhizosphere growth-promoting bacteria, and commercial products of plant rhizosphere growth-promoting bacteria well known to those skilled in the art can be used. The strain density of the plant rhizosphere growth-promoting bacteria is 1×10 5 -1×10 6 cfu / g.

[0034] The second aspect of the present invention is to provide a method for preparing the composite sustained-release bacterial agent composition according to the above, comprising the following steps:

[0035] S1, mixing arbuscular mycorrhizal fungi, plant rhizosphere growth-promoting bacteria, and a salicylate aqueous solution to obtain a mixture;

[0036] S2, dropping the mixture obtained in step S1 into an aqueous alginate solution to form a mixed solution;

[0037] S3, mixing the mixed solution obtained in step S2 with a calcium chloride aqueous solution, and solidifying the mixture to obtain a composite sustained-release bacterial agent composition.

[0038] In some embodiments of the present invention, the mixed solution in step S2 is formed by any one of extrusion, emulsification and spray drying. Preferably, the mixed solution is formed by extrusion.

[0039] In some embodiments of the present invention, the mixing temperature in step S1 is room temperature.

[0040] In some embodiments of the present invention, the mixing temperature in step S3 is room temperature.

[0041] In some embodiments of the present invention, the solidification is carried out at room temperature after the mixing in step S3, and the liquid is completely formed into solid spheres. The mixing method in step S3 is to squeeze the mixed solution obtained in step S2 into the calcium chloride aqueous solution using a sterile syringe; preferably, the needle hole diameter of the sterile syringe is 0.5-1mm.

[0042] The third aspect of the present invention is to provide a method for improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry and hot valley region, comprising the following steps: mixing the above-mentioned composite slow-release bacterial agent composition or the composite slow-release bacterial agent composition obtained by the above-mentioned preparation method, seedlings, and seedling soil, placing them in a planting pit, and maintaining them.

[0043] The present invention mixes the composite slow-release bacterial agent composition with the plant that can be infected by the strain of the arbuscular mycorrhizal fungi agent, so that the strain spores in the arbuscular mycorrhizal fungi agent can infect the root cells of the plant to form a mycorrhizal symbiont; the extended hyphae of the mycorrhizal symbiont has a higher specific surface area and length than the infected plant root system, and the hyphae can absorb nutrients, transport water and oxygen. Therefore, the arbuscular mycorrhizal fungi agent in the composite slow-release bacterial agent composition can improve the plant's ability to absorb and assimilate nitrogen, phosphorus and other substances, improve the efficiency of water utilization, and improve the plant's ability to find oxygen under oxygen stress, thereby improving the plant's ability to survive under flooding and drought stress.

[0044] The present invention can improve the abundance and diversity of rhizosphere microorganisms, thereby improving the stress resistance of plants in flooded and drought states and improving the survival rate of plants.

[0045] The plant rhizosphere growth-promoting bacteria of the composite slow-release bacterial agent composition of the present invention can secrete antioxidant enzymes to alleviate peroxidation damage under drought stress, thereby improving the survival ability of plants under drought stress.

[0046] The sodium alginate solution of the composite sustained-release bacterial agent composition of the present invention can be used as an embedding agent to embed the composite bacterial agent to form microcapsules, which can help the sustained release of the bacterial agent and prolong the effective time of the bacterial agent. The sodium salicylate solution can stimulate the growth of plant roots and colonize transplanted seedlings as soon as possible. The calcium chloride solution can be used as a curing agent to solidify the formed microcapsules for easy storage and transportation.

[0047] In some embodiments of the present invention, the size of the hole depends on the root system of the seedling. When planting the seedling, one hand should straighten the seedling and the other hand should fill it flat. When the soil is filled to the point where the root system is not exposed, gently lift the seedling, cover it with soil and tamp it down, and water it enough to fix the roots. Preferably, the seedling is selected to have many roots and soil. The present invention does not specifically limit the transplanting method of the seedlings, and the method of transplanting commonly used by those skilled in the art can be adopted. After lifting the seedlings, the present invention grades the young seedlings according to the growth of the seedlings, places seedlings with similar growth together, and eliminates seedlings with weak growth, severely damaged root systems and no future for cultivation; when lifting the seedlings, the roots are accompanied by soil balls, the diameter of the soil balls is 3 to 5 times the ground diameter, and some branches and leaves are trimmed. After lifting the seedlings, the overly long and split roots are trimmed, and the roots are immediately dipped in mud or temporary transplanting measures are taken to treat the seedlings after cutting the roots.

[0048] In some embodiments of the present invention, after the soil is cleaned, deep plowing is performed, and the composite slow-release bacterial agent composition is mixed into the deep plowed soil during the plowing process.

[0049] In some embodiments of the present invention, the seedling is a plant that can be infected by the species of the arbuscular mycorrhizal fungal agent; preferably, the seedling is selected from one or more of mulberry, water birch, Zhongshan fir, Jatropha curcas, Chinese tallow tree, maple poplar and Pyracantha fortuneana. Further preferably, the seedling is a seedling with a soil ball, and the radius of the soil ball is 5-10 cm.

[0050] In some embodiments of the present invention, the mass ratio of the composite slow-release bacterial agent composition to the seedling raising soil is 1:3-5. Specifically, the mass ratio can be 1:3, 1:4, 1:5; and the seedling raising soil is air-dried soil.

[0051] The present invention is further described below by way of examples, but the scope of the present invention is not limited thereto.

[0052] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. If specific conditions are not specified in the embodiment, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for all reagents or instruments, they are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any method, equipment, and material of the prior art similar or equivalent to the method, equipment, and material in the embodiments of the present invention can also be used to realize the present invention.

[0053] Example

[0054] Example 1

[0055] The composite sustained-release bacterial agent composition of this embodiment includes the following raw materials by weight: 20-30 parts of arbuscular mycorrhizal fungi powder, 15-20 parts of plant rhizosphere growth-promoting bacteria, 20-30 parts of sodium alginate aqueous solution, 5-10 parts of sodium salicylate aqueous solution, and 10-20 parts of calcium chloride solution. The arbuscular mycorrhizal fungi species are composed of Glomus radicifolius, Glomus mosesi, and Glomus terrestris in a mass ratio of 1:1:1; the number of spores in the arbuscular mycorrhizal fungi is 50-100 / g; the plant rhizosphere growth-promoting bacteria are selected from Bacillus subtilis, Pseudomonas and Serratia in a mass ratio of 1:1:1; the strain density of the plant rhizosphere growth-promoting bacteria is 1×10 5 -1×10 6 cfu / g. The mass percentage concentration of the calcium chloride aqueous solution is 3%; the mass percentage concentration of the alginate aqueous solution is 3%; and the concentration of the salicylate aqueous solution is 100 ppm.

[0056] The preparation method of the composite sustained-release bacterial agent composition of this embodiment comprises the following steps:

[0057] S1, mixing arbuscular mycorrhizal fungi, plant rhizosphere growth-promoting bacteria, and a salicylate aqueous solution to obtain a mixture;

[0058] S2, dropping the mixture obtained in step S1 into an aqueous alginate solution to form a mixed solution;

[0059] S3. Use a sterile syringe with a needle hole diameter of 0.9 mm to squeeze the mixed solution obtained in step S2 into a calcium chloride aqueous solution. After solidifying at room temperature for 30 minutes, use a 2 mm mesh sieve to screen the solidified sustained-release capsules to obtain a composite sustained-release bacterial agent composition.

[0060] Example 2

[0061] A method of improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry and hot valley region of the present embodiment comprises the following steps: adding the composite slow-release bacterial agent composition prepared in Example 1 to a seedling pot plant, simulating the drought and flooding conditions of the drawdown zone of a hydropower station reservoir in the dry and hot valley region of the Jinsha River, observing the seedling state, and calculating the survival rate. The seedling height is 80 cm. The seedling is a mulberry tree. The soil in the pot plant is air-dried soil. The size of the pot was 22.5 cm (lower pot bottom diameter) * 43 cm (upper pot bottom diameter) * 50 cm (height), the number of pots was 30, the amount of the composite slow-release bacterial agent added to each pot was 50 g, the soil moisture in each pot was adjusted to simulate the drought and flooding state, the soil moisture in the drought state was maintained at 30% of the saturated field water holding capacity, and the flooding state was set to flood more than 50 cm above the soil surface, the state of the transplanted seedlings was observed, and after 30 days, the survival rate of the seedlings was counted. The standard for seedling survival was that the seedlings grew new buds or new leaves, and the standard for seedling death was that the leaves dried up and the plants dried up. The results are as follows Figure 1shown.

[0062] Example 3

[0063] The method for improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region in this embodiment is different from that in Embodiment 2 in that the seedlings are Sapium sebiferum.

[0064] Example 4

[0065] The method for improving the survival rate of transplanting saplings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region in this embodiment is different from that in Embodiment 2 in that the saplings are maple poplar.

[0066] Comparative Example

[0067] Comparative Example 1

[0068] The method for improving the survival rate of transplanted seedlings in the drawdown zone of the hydropower station reservoir in the dry-hot valley region of this comparative example is different from that of Example 2 in that the composite slow-release bacterial agent composition is subjected to high-temperature inactivation treatment at a temperature of 300-400°C and a time of 2 hours.

[0069] Comparative Example 2

[0070] The method for improving the survival rate of transplanted saplings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region in this comparative example is different from comparative example 1 in that the saplings are Sapium sebiferum.

[0071] Comparative Example 3

[0072] The method for improving the survival rate of transplanting saplings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region in this comparative example is different from comparative example 1 in that the saplings are maple poplar.

[0073] Table 1 Survival rate of transplanted seedlings in the fluctuating zone of Examples 2-4 and Comparative Examples 1-3

[0074]

[0075] Combined with Examples 2-4, Comparative Examples 1-3, and Figure 1 According to the data in Table 1, the survival rate of the transplanted seedlings in Example 2-4 is much higher than that in Comparative Example 1-3. The difference between Example 2-4 and Comparative Example 1-3 is that the resurrection slow-release bacterial agent composition is added during the transplantation of the seedlings in Example 2-4. Therefore, it can be concluded that the composite slow-release bacterial agent composition can significantly improve the survival rate of plants under drought and flooding conditions.

[0076] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A composite sustained-release bacterial composition, characterized in that: The composition comprises the following raw materials in parts by weight: 20-30 parts of arbuscular mycorrhizal fungus powder, 15-20 parts of plant rhizosphere growth-promoting bacteria, 20-30 parts of alginate aqueous solution, 5-10 parts of salicylate aqueous solution and 10-20 parts of calcium chloride solution.

2. The composite sustained-release bacterial agent composition according to claim 1, characterized in that: Also includes one or more of the following characteristics: 1) The species of the arbuscular mycorrhizal fungi is selected from one or more of Glomus radicifolius, Glomus mosseae, Glomus terrestriale and Glomus juvenilee; 2) The arbuscular mycorrhizal fungi are composed of fungal spores, hyphae and plant roots that coexist with the fungal species; 3) The mass percentage concentration of the calcium chloride aqueous solution is 2-5%; 4) The alginate aqueous solution is selected from a sodium alginate aqueous solution or a potassium alginate aqueous solution; 5) The mass percentage concentration of the alginate aqueous solution is 1.5-3%; 6) The salicylate aqueous solution is selected from a sodium salicylate aqueous solution or a potassium salicylate aqueous solution; 7) The concentration of the salicylate aqueous solution is 100-150 ppm.

3. The composite sustained-release bacterial agent composition according to claim 2, characterized in that: The number of spores of the arbuscular mycorrhizal fungi is 50-100 / g.

4. The composite sustained-release bacterial agent composition according to claim 1, characterized in that: The plant rhizosphere growth-promoting bacteria are selected from one or more of Bacillus subtilis, Pseudomonas and Serratia.

5. The composite sustained-release bacterial agent composition according to claim 4, characterized in that: The strain density of the plant rhizosphere growth-promoting bacteria is 1×10 5 -1×10 6 cfu / g.

6. A method for preparing the composite sustained-release bacterial agent composition according to any one of claims 1 to 5, characterized in that: The steps include: S1, mixing arbuscular mycorrhizal fungi, plant rhizosphere growth-promoting bacteria, and a salicylate aqueous solution to obtain a mixture; S2, dropping the mixture obtained in step S1 into an aqueous alginate solution to form a mixed solution; S3, mixing the mixed solution obtained in step S2 with a calcium chloride aqueous solution, and solidifying the mixture to obtain a composite sustained-release bacterial agent composition.

7. The method for preparing the composite sustained-release bacterial agent composition according to claim 6, characterized in that: The mixed solution in step S2 is formed by any one of extrusion, emulsification and spray drying.

8. A method for improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry and hot valley region, characterized in that: The method comprises the following steps: mixing the composite slow-release bacterial agent composition described in any one of claims 1 to 5 or the composite slow-release bacterial agent composition prepared by the preparation method described in any one of claims 6 to 7, seedlings and seedling soil, placing the mixture in a planting pit, and maintaining the mixture.

9. The method for improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region according to claim 8, characterized in that: The seedlings are plants that can be infected by the species of arbuscular mycorrhizal fungi; preferably, the seedlings are selected from one or more of mulberry, water birch, Zhongshan fir, Jatropha curcas, Chinese tallow tree, maple poplar and pyracantha.

10. The method for improving the survival rate of transplanted seedlings in the drawdown zone of a hydropower station reservoir in a dry-hot valley region according to claim 8, characterized in that: The mass ratio of the composite slow-release bacterial agent composition to the seedling raising soil is 1:3-5.

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