Method for repairing saline-alkali soil through targeted domestication of arbuscular mycorrhizal fungi by compost product

Abstract

The invention relates to the crossing field of ecological restoration, soil restoration and solid waste resource utilization, in particular to a method for restoring saline-alkali soil through targeted domestication of arbuscular mycorrhizal fungi by compost products, which comprises the following steps: analyzing physical and chemical factors and biological characteristics of target compost products possibly influencing AMF colonization, screening AMF strains, carrying out stress culture, and screening the AMF strains. The target AMF strain adapts to the environment of the target compost product and the saline-alkali soil; propagating the targeted AMF strain to obtain an AMF propagated body; and the target compost product and the AMF expanding body are applied to saline-alkali soil to be repaired, plants are planted, the field is normally managed, and the plants are collected. According to the method, through precise screening, stress domestication and a multi-element synergistic strategy, the synergistic remediation efficiency of compost and AMF in the saline-alkali environment is remarkably enhanced, the remediation efficiency, stability and sustainability of the saline-alkali soil are improved, and safe value-added utilization of compost resources is promoted.

Description

Technical Field

[0001] The present invention relates to the intersecting fields of ecological restoration, soil restoration and solid waste resource utilization, and in particular to a method for repairing saline-alkali land by targeted domestication of arbuscular mycorrhizal fungi using compost products. Background Art

[0002] Globally, the intensification of agriculture and the acceleration of urbanization present dual challenges. On the one hand, the long-term reliance on chemical fertilizers in intensive agriculture has led to a deterioration in soil physical and chemical properties and a significant decline in soil fertility, posing a serious threat to sustainable agricultural development. On the other hand, accelerated urbanization has led to a sharp increase in the production of organic solid waste (such as food waste, sewage sludge, and livestock and poultry manure), placing enormous pressure on the environment and necessitating the urgent need to find effective ways to utilize this resource.

[0003] In this context, converting organic solid waste into organic fertilizer through bioconversion technologies such as composting and applying it to soil improvement has become a key strategy for balancing waste treatment and soil health maintenance. Studies have shown that compost products are rich in organic matter, nutrients, humus, and beneficial microbial metabolites, which can effectively improve soil structure, enhance soil fertility, and enhance soil microbial activity. This strategy not only provides a feasible solution for the resource utilization of organic solid waste, but also provides important support for sustainable agricultural development and soil health maintenance.

[0004] At the same time, soil salinization has become a major global ecological and environmental problem. Extensive saline-alkali land severely restricts agricultural development and ecological restoration. Traditional soil improvement methods, including physical methods (such as leaching) and chemical methods (such as the application of amendments), can alleviate soil salinization to a certain extent. However, these methods often have limitations, such as high costs, short-term effects, and the potential for secondary pollution.

[0005] In recent years, bioremediation technologies that leverage plant-microbe synergy, particularly the application of arbuscular mycorrhizal fungi (AMF), have demonstrated tremendous potential. These fungi can form symbioses with the roots of most terrestrial plants, significantly enhancing the host plant's ability to absorb water and nutrients and improving its tolerance to abiotic stresses such as salt stress, drought, and heavy metals. Furthermore, AMF can effectively improve soil structure, stability, and fertility by secreting substances such as glomalin. This bioremediation-based strategy is not only environmentally friendly but also achieves long-term, stable soil improvement effects, providing a sustainable solution to the challenge of soil salinization.

[0006] Therefore, there is an urgent need to develop a new method that can both utilize the organic solid waste generated by the urbanization process and repair soil salinization. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the object of the present invention is to provide a method for repairing saline-alkali land by targeting and domesticating arbuscular mycorrhizal fungi with compost products, which is used to solve the problems of difficulty in repairing saline-alkali soil and difficulty in treating organic solid waste in the prior art. The method for repairing saline-alkali land of the present invention is to target and domesticate arbuscular mycorrhizal fungi based on the characteristics of compost products, and construct a multi-component synergistic system with compost products, functional microorganisms, modified biochar, etc., to achieve safe value-added utilization of compost products and significantly improve the repair efficiency, stability and sustainability of degraded soils such as saline-alkali land. The core innovation of the present invention is: 1) using the physicochemical properties of the compost product itself (including potential stress factors) as selection pressure, targeted screening and domestication of AMF strains that are dually adapted to the compost matrix and the target repair environment (such as saline-alkali); 2) in-depth exploration and strengthening of the synergistic mechanism of compost products and adaptive AMF under saline-alkali stress to achieve a "1+1>2" repair effect.

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

[0009] The present invention provides a method for repairing saline-alkali land by targeted domestication of arbuscular mycorrhizal fungi using compost products, the method comprising the following steps:

[0010] Step 1: Screening and propagation of arbuscular mycorrhizal fungi

[0011] (1) Analyze the physicochemical factors and biological characteristics of the target compost products that may affect AMF colonization;

[0012] (2) Based on the analysis results of step (1) and the requirements for saline-alkali land restoration, AMF strains are screened, and the target compost product, host plant, sterilized sand containing mixed salts, and the screened AMF are co-cultured to observe the salt-alkali tolerance of the host plant to obtain a targeted AMF strain that is adapted to the target compost product environment and saline-alkali land;

[0013] (3) propagating the targeted AMF strain obtained in step (2) in a culture medium with a host plant as a host to obtain an AMF propagation body; the culture medium comprises the following raw materials: target compost product and saline-alkali material;

[0014] Step 2: Build a compost-AMF synergistic remediation system

[0015] (4) preparing a synergistic remediation mixture; the synergistic remediation mixture comprises the following raw materials: target compost product, saline-alkali soil to be remediated, and the AMF expansion prepared in step (3);

[0016] (5) applying the synergistic remediation mixture prepared in step (4) to the saline-alkali soil to be remediated, planting plants, performing normal field management, and collecting the plants; the plants are selected from one or more salt-alkali tolerant crops or pioneer plants.

[0017] As described above, the method of the present invention for repairing saline-alkali land by targeting acclimation of arbuscular mycorrhizal fungi with compost products has the following characteristics:

[0018] Beneficial effects:

[0019] (1) Precision targeting and enhanced adaptability: By utilizing the inherent characteristics of compost products for targeted screening and stress acclimation, the obtained AMF has dual high adaptability to the target compost matrix and saline-alkali environment, significantly improving its colonization success rate and functional efficiency in practical applications.

[0020] (2) Maximizing the synergistic effect of compost and AMF: This method makes full use of the positive feedback synergistic mechanism between the organic matter and nutrients provided by compost and the ability of AMF to promote plant absorption and enhance stress resistance. Especially under saline-alkali stress, the improvement of soil physicochemical properties by compost and the enhancement of plant physiological tolerance by AMF complement each other, achieving a repair effect far superior to that of applying either alone.

[0021] (3) The restoration of saline-alkali land is highly targeted: The method is designed around the characteristics of saline-alkali land, from AMF screening, propagation, selection of synergistic components to screening of crop varieties, reflecting a systematic response strategy to saline-alkali stress.

[0022] (4) Safety and resource utilization: While ensuring the restoration effect, the present invention effectively utilizes compost, an organic waste resource, to alleviate its potential environmental risks and reduce restoration costs, which is in line with the concepts of circular economy and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a schematic diagram of the method for repairing saline-alkali land by targeted domestication of arbuscular mycorrhizal fungi using compost products of the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] The combined application of compost products and AMF for saline-alkali soil improvement has theoretical synergistic advantages. Compost improves the soil's physical and chemical environment, providing a favorable substrate for AMF colonization. AMF, in turn, enhances plant survival and growth under saline-alkali stress, accelerating vegetation recovery and soil desalination. However, existing research and practice often suffer from the following deficiencies: 1. Indiscriminate selection of AMF strains. Currently, most commercial AMF strains are generic or have not been screened for specific environments. These strains may be poorly adapted to specific saline-alkali environments and compost substrates, resulting in low colonization efficiency and limited functionality. 2. Ignoring the complexity of compost products. Compost comes from diverse sources, and its physical and chemical properties (such as residual salt, pH, heavy metals, organic pollutants, and endogenous microorganisms) vary significantly. These characteristics may directly affect the survival, colonization, and function of AMF, and may even pose potential ecological risks. Existing methods fail to fully consider and utilize the characteristics of compost products for targeted AMF screening. 3. The synergistic mechanism is not fully utilized. Simply mixing compost and AMF for application fails to deeply explore and strengthen the specific synergistic mechanism between the two under saline-alkali stress, resulting in "1+1<2" or even an antagonistic effect, and the repair effect is unstable and inefficient.

[0026] Therefore, there is an urgent need to develop a new technical approach that can, based on the physical, chemical and biological properties of compost products, target the screening and domestication of efficient AMF strains that are dually adapted to specific compost matrices and target saline-alkali environments, and construct an optimized synergistic system with AMF as the core, combined with compost, possible functional microorganisms and other improvement measures, aiming to overcome the limitations of existing technologies, achieve safe and efficient resource utilization of compost products, and significantly improve the success rate, efficiency and sustainability of saline-alkali land ecological restoration.

[0027] Arbuscular mycorrhizal fungi (AMF) are a type of fungus that forms a symbiotic relationship with plant roots. By forming branched and network-like structures on plant roots, they help plants absorb water and minerals from the soil. This can improve plant resistance to abiotic stresses such as drought, salinity, heavy metals, and organic pollution, as well as biotic stresses caused by other organisms, and regulate the synthesis of plant secondary metabolites. The glomalin secreted by these fungi can also improve soil aggregate structure. The core of the present invention lies in recognizing and utilizing the complex interactive relationship between compost products and AMF. Compost is not only a potential substrate for AMF proliferation, but the organic matter, nutrients, humic acid, and certain microbial metabolites it contains can directly or indirectly affect AMF growth, colonization, and function. Furthermore, potential stress factors such as salt and heavy metals in compost also provide unique selective pressure for screening and domesticating AMF adapted to specific environments. Through the targeted screening and stress domestication steps of the present invention, "tailor-made" AMF strains can be obtained, enabling them to stably perform ecological restoration functions in soil environments rich in compost and subject to saline-alkali stress.

[0028] The innovative method proposed in this invention goes beyond the simple combined application of AMF and compost. By introducing strategies such as targeted screening, stress acclimation, multi-factor synergy and precise regulation, a more efficient and green ecological restoration system is constructed. Figure 1 As shown, the system operation steps are mainly divided into three stages:

[0029] Phase 1 involves targeted AMF screening and adaptive propagation. The starting point is the current status of the saline-alkali land to be remediated and the specific compost resources available. First, the compost product to be used undergoes a comprehensive analysis of its physicochemical properties (such as pH, EC, organic matter, nutrient content, and degree of humification) and biological characteristics (endogenous microbial community), with particular attention paid to salt content and contaminants that may affect AMF, such as heavy metals and antibiotics. Second, based on the compost analysis results and the saline-alkali land remediation objectives, a two-step screening process is conducted. 1) Primary screening: Candidate strains with salt tolerance or composting environment adaptability are initially selected from the AMF strain library. 2) Secondary screening: Functional verification of the initially screened strains is performed using a culture medium containing the target compost product and simulating saline-alkali stress. By comparing the colonization efficiency, reproductive capacity, and salt tolerance enhancement of the host plant under stress conditions, "compost-salt-alkali dual-adapted" AMF strains are precisely selected to efficiently survive, colonize, and function in the target compost environment. Furthermore, the optimal targeted AMF strains obtained through repeated screening were inoculated into a specific culture medium (comprising soil, target compost products, quartz sand, and vermiculite) with salt-tolerant plants as hosts. During the propagation process, moderate salt stress was continuously applied, supplemented with Hoagland nutrient solution, to induce and enhance the salt tolerance of the AMF. Finally, the above-ground parts were removed, and the roots, along with the culture medium, were processed to obtain stress-resilient AMF propagations containing highly active and adaptable AMF spores, hyphae, infected root segments, and an adaptive matrix.

[0030] Phase II involves constructing a compost-AMF synergistic remediation system. The stress-adapted AMF expansion generated in Phase I is mixed with additional target compost products (which serve as the primary soil conditioner and sustainable habitat for AMF) and the saline-alkali soil to be remediated in an optimized ratio. Salt-tolerant microbial agents (such as PGPR) and / or modified biochar are selectively added as needed to create a synergistic remediation matrix. The prepared synergistic remediation matrix is ​​evenly applied to the target saline-alkali plot, followed by the planting of selected salt-tolerant cash crops or pioneering plants.

[0031] Phase three is the regulation and sustainable management of the rhizosphere microecology. First, during the critical growth period of crops, low concentrations of AMF signal molecules (such as GR24 and specific flavonoids) are selectively applied and delivered to the root zone through irrigation and other means to actively promote the early and rapid colonization and functional activation of AMF. Secondly, after the first crop is harvested, the improvement of soil salinity and the status of the AMF population are evaluated. Based on this information, suitable subsequent rotation crops (such as leguminous green manure, salt-tolerant forage, etc.) are selected for planting. Finally, through a scientific rotation system, the established AMF community is maintained and consolidated, the soil microecological environment is continuously improved, and the long-term and stable restoration of saline-alkali land and the gradual improvement of soil health levels are achieved, ultimately achieving the goal of sustainable utilization.

[0032] The main innovation of the present invention is that the compost product and the adaptive AMF work synergistically in improving saline-alkali land. The synergistic effect is reflected in the following three aspects: 1) Physical level: compost improves soil structure, porosity and water holding capacity, providing a good environment for the expansion of AMF hyphae network; AMF hyphae and their secretions glomalin further stabilize soil aggregates, and jointly resist the damage of salt to soil structure. 2) Chemical level: compost provides slow-release nutrients, buffering soil pH and salinity fluctuations; AMF expands the root absorption range, efficiently absorbs nutrients such as phosphorus and nitrogen, and may help plants reduce Na by regulating ion channels, compartmentalization and other mechanisms. + Absorption, increase K + , Ca 2+ Mg 2+ 3) Biologically: Beneficial microorganisms introduced by compost may interact with AMF to promote plant growth or degrade organic pollutants in the soil. The establishment of AMF can improve the rhizosphere microenvironment and attract more beneficial microorganisms to colonize. This multi-dimensional synergy makes the combined application of compost and AMF in saline-alkali land remediation far more effective than either single approach.

[0033] The present invention provides a method for repairing saline-alkali land by targeted domestication of arbuscular mycorrhizal fungi using compost products, the method comprising the following steps:

[0034] Step 1: Screening and propagation of arbuscular mycorrhizal fungi

[0035] (1) Analyze the physicochemical factors and biological characteristics of the target compost products that may affect AMF colonization;

[0036] (2) Based on the analysis results of step (1) and the requirements for saline-alkali land restoration, AMF strains are screened, and the target compost product, host plant, sterilized sand containing mixed salts, and the screened AMF are co-cultured to observe the salt-alkali tolerance of the host plant to obtain a targeted AMF strain that is adapted to the target compost product environment and saline-alkali land;

[0037] (3) propagating the targeted AMF strain obtained in step (2) in a culture medium with a host plant as a host to obtain an AMF propagation body; the culture medium comprises the following raw materials: target compost product and saline-alkali material;

[0038] Step 2: Build a compost-AMF synergistic remediation system

[0039] (4) preparing a synergistic remediation mixture; the synergistic remediation mixture comprises the following raw materials: target compost product, saline-alkali soil to be remediated, and the AMF expansion prepared in step (3);

[0040] (5) applying the synergistic remediation mixture prepared in step (4) to the saline-alkali soil to be remediated, planting plants, performing normal field management, and collecting the plants; the plants are selected from one or more salt-alkali tolerant crops or pioneer plants.

[0041] In some embodiments of the present invention, the method for screening AMF strains in step (2) comprises the following steps: co-culturing the water extract of the compost product with AMF spores, with an inoculum size of 10-50 spores per culture dish, and judging the colonization ability and reproductive ability of different AMF strains by comparing the germination rate, hypha length, and branch number of the AMF spores.

[0042] The water extract of the compost product has a volume ratio of compost product to deionized water of 1:10 and is shaken at 25° C. for 24 hours.

[0043] In some embodiments of the present invention, the physicochemical factors and biological characteristics that may affect AMF colonization in step (1) are selected from one or more of pH, water-soluble salt content, organic matter content, nitrogen, phosphorus and potassium content, humification degree, heavy metal content, residual antibiotic content or endogenous microbial community structure.

[0044] In some embodiments of the present invention, the method for screening AMF in step (2) can be to preliminarily screen out AMF strains (such as certain Rhizophagus, Funneliformis, and Claroideoglomus strains) that are known to have good salt tolerance or perform well in similar compost matrices from an AMF strain resource library based on literature or experimental data.

[0045] In some embodiments of the present invention, the mixed salt in step (2) is selected from one or more of NaCl, Na2SO4, NaHCO3 or Na2CO3.

[0046] In some embodiments of the present invention, the host plant in step (2) is a salt-alkali tolerant plant. Preferably, the salt-alkali tolerant plant is selected from one or more of the Poaceae, Chenopodiaceae or Leguminosae. Further preferably, the salt-alkali tolerant plant is selected from one or more of the Lolium perenne, Suaeda salsa and Sorghum bicolor.

[0047] In some embodiments of the present invention, the targeted AMF strain in step (2) is selected from arbuscular mycorrhizal fungi (Glomeromycota), preferably, the targeted AMF strain is selected from one or more of the genera Rhizophagus, Funneliformis or Claroideoglomus.

[0048] The saline-alkali land of the present invention refers to land with excessive soluble salts in the soil, which affects plant growth. The need for saline-alkali land restoration refers to improving soil fertility, reducing salinity, optimizing physical and chemical properties, and making it suitable for growing crops. Specifically, improving soil fertility means supplementing the organic matter in the soil (such as increasing the application of organic fertilizers and planting green manures), microbial agents (such as nitrogen-fixing bacteria and phosphate-solubilizing bacteria), repairing degraded soil biomes, and enhancing water and fertilizer retention capabilities.

[0049] Step (2) of the present invention utilizes the target compost product or its extract as a key screening factor. A series of culture substrates containing different proportions of target compost product and simulated saline-alkali stress (such as adding mixed salts such as NaCl and Na2SO4) are set up, the candidate AMF strains obtained by the initial screening are inoculated, and host plants with salt tolerance or moderate salt tolerance (such as ryegrass, Suaeda salsa, sorghum, etc.) are planted. By comparing the colonization rate, spore yield, mycelial growth status of AMF under different treatments and the effect of improving the salt tolerance of host plants, a targeted AMF strain with "compost-salt-alkali dual adaptation" that is not only salt-tolerant but also able to efficiently colonize and function in the target compost product environment is screened out.

[0050] The screening indexes of the present invention are spore germination rate>60%, average hypha length>500 μm, and hypha branch number>3.

[0051] In some embodiments of the present invention, the host plant in step (3) is a salt-alkali tolerant plant. Preferably, the salt-alkali tolerant plant is selected from one or more of the Poaceae, Chenopodiaceae or Leguminosae. Further preferably, the host plant is selected from one or more of the Lolium perenne, Suaeda salsa and Sorghum bicolor.

[0052] In some embodiments of the present invention, the culture medium in step (3) comprises the following raw materials: target compost product and sterilized sand; preferably, the amount of target compost product added is 10-20% of the sterilized sand;

[0053] Step (3) of the present invention uses the targeted AMF strain screened in step (2) and propagates it in a specific culture medium using salt-tolerant host plants (such as Suaeda salsa and Suaeda salsa) as hosts. During the propagation process, Hoagland nutrient solution is irrigated and moderate salt stress is maintained to induce and consolidate the salt tolerance of AMF. After the propagation is completed, the above-ground part is cut off, and the root system is processed together with the culture medium to finally obtain an expanded body containing highly active and adaptable AMF spores, hyphae, infected root segments and an adaptable matrix.

[0054] In some embodiments of the present invention, the saline-alkali substance in step (3) is a nutrient solution containing a saline-alkali substance, specifically, the nutrient solution is Hoagland nutrient solution. Furthermore, the saline-alkali substance is a Hoagland nutrient solution containing a simulated salt, wherein the simulated salt is selected from one or more of NaCl, Na2SO4, NaHCO3, or Na2CO3. The content of the simulated salt in the Hoagland nutrient solution is controlled according to the salt content of the soil to be remediated.

[0055] In some embodiments of the present invention, the AMF expansion medium in step (3) comprises spores, hyphae, and infected host plant root segments of the targeted AMF strain.

[0056] In some embodiments of the present invention, the synergistic repair mixture in step (4) further includes a salt-tolerant functional microbial agent; the inoculation concentration of the salt-tolerant functional microbial agent is 10 6 -10 8 CFU / g dry basis or 10 7 -10 9 CFU / mL irrigation liquid; preferably, the salt-tolerant functional microbial agent is selected from one or more of plant growth promoting rhizobacteria (PGPR) and salt stress alleviating bacteria; the PGPR is salt-tolerant / halophilic, specifically, the PGPR can be a Bacillus or Pseudomonas strain that solubilizes phosphate / potassium / nitrogen; the salt stress alleviating bacteria can be a strain that produces ACC deaminase; further preferably, the salt-tolerant functional microbial agent comprises a strain selected from Bacillus velezensis or Pseudomonas. Wherein, the dry agent here includes the target compost product, the saline-alkali soil to be repaired, and the AMF expansion body obtained in step (3).

[0057] In some embodiments of the present invention, the synergistic remediation mixture in step (4) further comprises modified biochar. The modified biochar is preferably alkaline (e.g., Ca / Mg-rich) or has a high cation exchange capacity, and is used to adsorb excess salt ions, buffer pH, improve soil structure, and serve as a slow-release carrier for AMF and functional microorganisms. The amount of modified biochar added is 0.5-1%, based on the amount of the synergistic remediation mixture added.

[0058] In some embodiments of the present invention, the mass ratio of the target compost product in step (4), the saline-alkali soil to be remediated, and the AMF expanded body obtained in step (3) is 1-2:8-9:0.2-0.5. Specifically, the mass ratios may be 1-1.5:8-8.5:0.2-0.4, 1.5-2:8.5-9:0.4-0.5; typical but non-limiting examples include 1:8:0.2 and 2:9:0.5.

[0059] In some embodiments of the present invention, the application method in step (5) can be any one of furrow application, hole application or mixed application.

[0060] In some embodiments of the present invention, the salt-alkali tolerant crops in step (5) are selected from one or more of cotton, sunflower, sweet sorghum, quinoa or alfalfa.

[0061] In some embodiments of the present invention, during the plant growth period in step (5), rhizosphere signal molecules are applied; preferably, the rhizosphere signal molecules are selected from one or more of strigolactone analogs or flavonoids. Specifically, during the critical growth period of the crop, such as the seedling stage or the period of increased stress, an appropriate amount of signal molecules that can promote the colonization of AMF or enhance its function, such as a low concentration of the strigolactone analog GR24 or a specific flavonoid, are applied by dripping through the irrigation system or watering the roots to enhance the early colonization and function of AMF.

[0062] In some embodiments of the present invention, step (5) further includes step (6), wherein after the plants are harvested, subsequent crops with high affinity for the established AMF are selected for rotation or intercropping based on the soil remediation status and the AMF population status. Specifically, after the first crop is harvested, subsequent crops (such as leguminous green manure and salt-tolerant forage) with high affinity for the established AMF community and whose root secretions are beneficial to maintaining soil structure or further improving the saline-alkali environment are selected based on the degree of soil salinity reduction, the abundance of the AMF population and the health of the soil. These crops are rotated or intercropped with the main crops to achieve long-term maintenance of the remediation effect and sustainable improvement of the ecosystem.

[0063] The present invention is further described below by way of examples, but the scope of the invention is not limited thereto.

[0064] When the embodiments provide numerical ranges, it should be understood that, unless otherwise specified in the present invention, both 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. In the embodiments, if specific conditions are not specified, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for all reagents or instruments, they are conventional products that can be obtained by commercial purchase. 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 methods, equipment, and materials in the embodiments of the present invention can also be used to realize the present invention.

[0065] The greenhouse conditions involved in the present invention are that the greenhouse environment is controlled at 25° C. (day) / 18° C. (night), the photoperiod is 16h / 8h, and the relative humidity is 60-70%.

[0066] The technical term "high-temperature aerobic composting" in the present invention refers to a conventional composting method in the art, and the composting temperature refers to the composting temperature in accordance with the "Hygienic Requirements for Harmless Treatment of Excrement GB 7959-2012" or the "Technical Specifications for Aerobic Fermentation Equipment for Domestic Organic Waste DB11 / T170-2015" standards.

[0067] Example: Targeted domestication of AMF using food waste compost products to synergistically restore saline-alkali land in Northwest China

[0068] 1. Experimental Materials

[0069] 1.1. Target Compost Product: This product is sourced from food waste collected centrally at a project site and fully decomposed through thermophilic aerobic composting, with a fermentation temperature above 55°C for at least three days. The compost product's basic indicators are: 42.5% organic matter, 3.1% total nitrogen, 1.9% total phosphorus, pH 7.5, EC value 9.2 mS / cm, relatively high salt content, and heavy metal indicators that meet the organic fertilizer standard NY / T525-2021.

[0070] 1.2. Saline-alkali soil to be remediated: Typical alkaline soil in a certain area of ​​Northwest China. Basic soil indicators are: pH 8.8, EC value 7.6mS / cm, organic matter 0.65%, available phosphorus 3.2mg / kg, available potassium 68mg / kg, soil texture is loam, Na + High content, accompanied by higher concentrations of HCO 3- and CO3 2- .

[0071] 1.3. AMF strains

[0072] Control AMF (C-AMF): a commercially available general-purpose Rhizophagus irregularis MUCL 41833 inoculant.

[0073] Targeted domesticated AMF (T-AMF): an AMF strain obtained by screening and domestication according to the method (1) of the present invention.

[0074] The initial screening process involves co-culturing the water extract of compost products with AMF spores. The colonization and reproductive abilities of different AMF strains are determined by comparing the germination rate, hyphal length, and number of branches of the AMF spores.

[0075] Specifically, in the initial screening phase, 5-10 AMF strains known to have a certain degree of salt tolerance were selected, and their spores were extracted for testing. The compost product was mixed with sterile water at a ratio of 1:5 (w / v), shaken and extracted for 2 hours. The supernatant was extracted and cultured with AMF spores in Petri dishes. The spore inoculum was 10-50 spores per dish. A control group was set up and incubated in a dark incubator for 10-20 days. AMF strains with excellent spore germination rates >60%, average hypha length >500 μm, and hyphae branch count >3 were selected. The known strains used in the initial screening were Rhizophagus irregularis, Funneliformis mosseae, Claroideoglomus etunicatum, Gigaspora margarita, Diversispora spurca, Septoglomus constrictum, Acaulospora scrobiculata, Glomus versiforme, Rhizophagus fasciculatus, and Paraglomus occultum. The AMF strains screened were Rhizophagusirregularis, Funneliformis mosseae, and Claroideoglomus etunicatum.

[0076] In the rescreening stage, root canal culture is used to co-culture the target compost product, host plant, sterilized sand containing mixed salts, and the AMF strain after the initial screening to observe the salt and alkali tolerance of the host plant and obtain targeted AMF strains that are adapted to the target compost product environment and saline-alkali land.

[0077] Specifically, in the re-screening stage, a sterilized sandy soil matrix containing 10% (w / w) of the above-mentioned food waste compost was used, and mixed salt (NaCl:Na2SO4:NaHCO3=1:1:2, simulating a saline-alkali soil environment) was added to achieve an EC value of 5.5mS / cm and a pH of approximately 8.6. Sorghum was used as the host, and the growth of sorghum was observed to screen out the dominant bacterial strain in the best sorghum growth group, which was the bacterium that performed best under the "food waste compost + saline-alkali" stress (preliminarily identified as Claroideoglomus etunicatum YL-NW-1).

[0078] During the stress-adaptive propagation phase, C. etunicatum YL-NW-1 was propagated on the salt-tolerant plant Suaeda salsa in sterilized sandy soil containing 10% composted food waste. During the propagation phase, the simulated salt concentration of the Hoagland nutrient solution was gradually increased to an EC value of 6.8 mS / cm and a pH of 8.7. The propagated strains were harvested, containing highly active spores (approximately 2500 per 10g), mycelium, infected root segments, and the adaptive substrate. The simulated salt was a mixed salt solution (NaCl:Na2SO4:NaHCO3 = 1:1:2, simulating a saline-alkali soil environment).

[0079] 1.4. The salt-tolerant functional microbial agent is Bacillus velezensis NW-PGPR-3, which is isolated from the saline-alkali soil in Northwest China and has good salt-alkali tolerance and the ability to promote nitrogen fixation.

[0080] 1.5. Modified biochar: corn straw was pyrolyzed at 550℃, activated by soaking in 0.5M H3PO4 solution, washed and dried. It has a pH of 6.8 and a high specific surface area (1000m 2 / g) and a certain phosphorus slow-release ability.

[0081] 1.6. Test plant: Sunflower (salt-alkali tolerant variety “Xinkuiza No. 18”).

[0082] 1.7. Signal molecules: flavonoids, quercetin or kaempferol.

[0083] 2. Experimental Methods

[0084] (1) Potted plant experiment

[0085] Flower pots were used as experimental carriers. Each pot contained 5 kg of soil and contained one sunflower. Multiple experimental groups were set up, with 6 replicates in each group. The experimental groups were set up as follows:

[0086] Experimental Group 1

[0087] CK: Northwest saline-alkali soil where only sunflowers are grown. Details are as follows:

[0088] Sunflowers were planted directly in saline-alkali soil in Northwest China and cultivated in a greenhouse (temperature 25°C, humidity 30%) for 120 days. Soil moisture was maintained by regular watering.

[0089] Experimental Group 2

[0090] CP: Northwest saline-alkali soil + food waste compost (add 5% of soil dry weight, i.e. 250g / pot). The details are as follows:

[0091] The composted food waste was evenly mixed with saline-alkali soil from Northwest China, and sunflowers were planted and cultivated in a greenhouse (temperature 25°C, humidity 30%) for 120 days. The soil was watered regularly to maintain moisture.

[0092] Experimental Group 3

[0093] C-AMF: Northwest saline-alkali soil + control AMF expansion (inoculation amount is calculated based on 1500 effective spores per kilogram of soil). The control AMF expansion was expanded using the method in step (3). The details are as follows:

[0094] The control AMF propagation was evenly applied to the saline-alkali soil in Northwest China, and sunflowers were planted and cultivated in greenhouse conditions for 120 days. Soil moisture was maintained by regular watering.

[0095] Experimental Group 4

[0096] T-AMF: Northwest saline-alkali soil + targeted domesticated AMF expansion (inoculation amount is the same as C-AMF). Details are as follows:

[0097] The targeted domesticated AMF propagation strain was evenly applied to the saline-alkali soil in Northwest China, and sunflowers were planted and cultivated in greenhouse conditions for 120 days. Soil moisture was maintained by regular watering.

[0098] Experimental Group 5

[0099] CP+C-AMF: Northwest saline-alkali soil + kitchen waste compost (5%) + control AMF expansion. Details are as follows:

[0100] Composted food waste and control AMF were evenly applied to saline-alkali soil in Northwest China, and sunflowers were planted and cultivated in a greenhouse for 120 days. Soil moisture was maintained by regular watering.

[0101] Experimental Group 6

[0102] CP+T-AMF (core combination of the present invention): Northwest saline-alkali soil + kitchen waste compost (5%) + targeted domesticated AMF expansion. Details are as follows:

[0103] Composted food waste and targeted domesticated AMF propagation were evenly applied to saline-alkali soil in Northwest China, where sunflowers were planted and cultivated in a greenhouse for 120 days. Soil moisture was maintained with regular watering.

[0104] Experimental Group 7

[0105] SYS (complete system of the present invention): Northwest saline-alkali soil + kitchen waste compost (5%) + T-AMF + functional microbial agent (according to 10 8 CFU / g dry soil applied) + modified biochar (added at 1% of soil dry weight, i.e. 50g / pot). Details are as follows:

[0106] Composted food waste, targeted AMF domestication propagation, functional microbial agents, and modified biochar were evenly applied to saline-alkali soil in Northwest China. Sunflowers were then planted and cultivated in a greenhouse for 120 days. Quercetin was applied to the roots at the beginning of the planting period to promote AMF colonization at a concentration of 10-20 mg / L. Regular watering was performed to maintain soil moisture.

[0107] (2) Cultivation and measurement: Each experimental group was replicated five times and cultured in a greenhouse for 120 days. Soil moisture was maintained by regular watering. Measurement at harvest:

[0108] Soil indicators: pH, EC value, organic matter, available phosphorus, available potassium, and exchangeable sodium ion percentage (ESP).

[0109] Plant indicators: plant height, aboveground dry weight, underground dry weight, and relative chlorophyll content in leaves (SPAD value).

[0110] AMF indicators: total root colonization rate (%), rhizosphere soil AMF spore density (spores / 10g dry soil), and glomalin-related soil protein (GRSP) content (mg / g soil).

[0111] 3. Experimental Results and Analysis

[0112] 1. Soil properties and analysis: The soil test results of different experimental groups are shown in Table 1.

[0113] Table 1 Soil properties test results of experimental groups 1-7

[0114]

[0115] Combining experimental groups 1-7 and the data in Table 1, we can see that:

[0116] Experimental group 1 used sunflower alone to treat saline-alkali soil, and the resulting soil had a high salinity and was poor in nutrients;

[0117] Experimental group 2 used food waste compost alone to treat saline-alkali soil. The organic matter content and some nutrient contents of the saline-alkali soil increased significantly after treatment, and it had a certain buffering effect on pH and EC. The overall improvement effect was average.

[0118] Experimental group 3 was inoculated with control AMF alone, and experimental group 4 was inoculated with targeted domesticated AMF alone. The overall improvement of soil physical and chemical properties in experimental groups 3 and 4 was not obvious, but the GRSP content of the soil in experimental group 4 was higher than that in the soil in experimental group 3. The AMF after targeted domestication had better activity in saline-alkali soil.

[0119] Experimental group 5 used food compost combined with control AMF to treat saline-alkali soil. The treatment effect of saline-alkali soil in experimental group 5 was better than that in experimental groups 2 and 3, but the effects of reducing soil pH, EC, ESP and improving nutrients were not good.

[0120] Experimental Group 6 combined food waste compost with targeted domesticated AMF to treat saline-alkali soil. The soil properties of Experimental Group 6 were significantly improved compared to the untreated saline-alkali soil. The difference from Experimental Group 5 was that the AMF was expanded differently, resulting in significantly improved soil properties. The pH, EC, and ESP values ​​of the soil treated in Experimental Group 6 decreased significantly (pH decreased by 0.3 units, EC decreased by 1.34 mS / cm, and ESP decreased by 5.3 percentage points), while the organic matter, available phosphorus, available potassium, and GRSP content, which reflects AMF activity, all increased significantly. This demonstrates that targeted domesticated AMF (T-AMF) has stronger adaptability and functional activity in the soda-salt environment of food waste compost, and can produce a strong synergistic effect with food waste compost, effectively improving saline-alkali soil.

[0121] Experimental group 7 added modified activated carbon and functional microbial agents to experimental group 6. As a result, various indicators of the saline-alkali soil after treatment were further improved, especially the reduction of pH and ESP and the increase of available phosphorus and potassium, which showed the auxiliary synergistic effect of functional microbial agents and modified biochar.

[0122] 2. Plant growth and AMF colonization analysis

[0123] The analysis of plant growth and AMF colonization under different experimental groups is shown in Table 2 .

[0124] Table 2 Effects of experimental groups 1-7 on sunflower growth and AMF colonization

[0125]

[0126] Treatment with experimental group 1 resulted in stunted growth of sunflowers. Treatment with experimental group 2 showed significant improvement. Treatments with experimental groups 3 and 4 had limited effects on sunflower growth, but treatment with experimental group 4 was superior to that with experimental group 3. Furthermore, treatment with experimental group 4 resulted in significantly higher colonization rates and spore densities in sunflowers, further demonstrating the adaptive advantages of targeted domestication of AMF.

[0127] The growth-promoting effects of experimental groups 5 and 6 on sunflower were better than those of experimental groups 2-4, but the plant growth indicators and AMF colonization levels in experimental group 5 were significantly lower than those in experimental group 6.

[0128] Experimental Group 6 demonstrated the strongest plant growth-promoting effect. Sunflower plant height, aboveground and belowground biomass, and chlorophyll content (SPAD value) were significantly higher than all other control treatments (except SYS). Furthermore, its root AMF colonization rate and rhizosphere spore density also reached the highest levels (except SYS). This directly demonstrates that targeted AMF domestication can efficiently colonize in saline-alkali soils amended with food waste compost and exert powerful growth-promoting and stress-resistance functions.

[0129] The plant growth indicators and AMF colonization levels of experimental group 7 reached the best, indicating that the addition of functional microbial agents and modified biochar can further optimize the rhizosphere environment, enhance the resistance of plants to stress, and synergize with food waste composting and targeted domesticated AMF.

[0130] Combining experimental groups 1-7 and the data in Tables 1 and 2, we can see that:

[0131] (1) Under the saline-alkali soil conditions in Northwest China, the improvement effect of applying food waste compost products or general AMF alone is limited.

[0132] (2) The method of the present invention for targeted domestication of arbuscular mycorrhizal fungi with compost products to repair saline-alkali land uses the characteristics of food waste composting and simulated saline-alkali stress to conduct targeted screening and domestication to obtain the AMF strain (Claroideoglomusetunicatum YL-NW-1, T-AMF), which has significant adaptability advantages to the target environment.

[0133] (3) The combined application of food waste compost and targeted domesticated AMF (CP+T-AMF, i.e., experimental group 6) produced a strong synergistic effect. This combination was significantly superior to the application of compost alone, AMF alone (whether general type, i.e., experimental group 3 or targeted type, i.e., experimental group 4), and the combination of compost and general AMF (CP+C-AMF, i.e., experimental group 5) in reducing soil pH, EC, and ESP, increasing soil organic matter and nutrient content, significantly promoting the growth of salt-tolerant plants, and increasing the colonization rate and activity of AMF.

[0134] (4) Further integration of functional microbial agents and modified biochar (SYS) based on experimental group 6 can achieve better remediation effects.

[0135] 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 skilled in 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 one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for restoring saline-alkali land by targeted domestication of arbuscular mycorrhizal fungi using compost products, characterized in that: The method comprises the following steps: Step 1: Screening and propagation of arbuscular mycorrhizal fungi (1) Analyze the physicochemical factors and biological characteristics of the target compost products that may affect AMF colonization; (2) Based on the analysis results of step (1) and the requirements for saline-alkali land restoration, AMF strains are screened, and the target compost product, host plant, sterilized sand containing mixed salts, and the screened AMF are co-cultured to observe the salt-alkali tolerance of the host plant to obtain a targeted AMF strain that is adapted to the target compost product environment and saline-alkali land; (3) propagating the targeted AMF strain obtained in step (2) in a culture medium with a host plant as a host to obtain an AMF propagation body; the culture medium comprises the following raw materials: target compost product and saline-alkali material; Step 2: Build a compost-AMF synergistic remediation system (4) preparing a synergistic remediation mixture; the synergistic remediation mixture comprises the following raw materials: target compost product, saline-alkali soil to be remediated, and the AMF expansion prepared in step (3); (5) applying the synergistic remediation mixture prepared in step (4) to the saline-alkali soil to be remediated, planting plants, performing normal field management, and collecting the plants; the plants are selected from one or more salt-alkali tolerant crops or pioneer plants.

2. The method according to claim 1, wherein: The physicochemical factors and biological characteristics that may affect AMF colonization in step (1) are selected from one or more of pH, water-soluble salt content, organic matter content, nitrogen, phosphorus and potassium content, humification degree, heavy metal content, residual antibiotic content or endogenous microbial community structure.

3. The method according to claim 1, wherein: It also includes one or more of the following technical features: 21) The mixed salt in step (2) is selected from one or more of NaCl, Na2SO4, NaHCO3 or Na2CO3; 22) The host plant in step (2) is a salt-alkali tolerant plant. Preferably, the salt-alkali tolerant plant is selected from one or more of the grass family, the Chenopodiaceae family or the leguminous family. More preferably, the host plant is selected from one or more of the ryegrass, the salsa sedge and the sorghum. 23) The targeted AMF strain in step (2) is selected from arbuscular mycorrhizal fungi (Glomeromycota), preferably, the targeted AMF strain is selected from one or more of the genera Rhizophagus, Funneliformis or Claroideoglomus.

4. The method according to claim 1, wherein: It also includes one or more of the following technical features: 31) The host plant in step (3) is a salt-alkali tolerant plant. Preferably, the salt-alkali tolerant plant is selected from one or more of Gramineae, Chenopodiaceae or Leguminosae. More preferably, the salt-alkali tolerant plant is selected from one or more of Lolium perenne, Suaeda salsa and Sorghum bicolor. 32) The culture medium in step (3) comprises the following raw materials: target compost product and sterilized sand; preferably, the amount of target compost product added is 10-20% of the sterilized sand; 33) The saline-alkali substance in step (3) is a nutrient solution containing saline-alkali substance; 34) The AMF expansion medium in step (3) comprises spores, hyphae, and infected host plant root segments of the targeted AMF strain.

5. The method according to claim 1, wherein: The synergistic repair mixture in step (4) further includes a salt-tolerant functional microbial agent; preferably, the inoculation concentration of the salt-tolerant functional microbial agent is 10 6 -10 8 CFU / g dry basis or 10 7 -10 9 CFU / mL irrigation fluid; further preferably, the salt-tolerant functional microbial agent is selected from one or more of plant growth promoting rhizobacteria (PGPR) and salt stress alleviating bacteria; even more preferably, the salt-tolerant functional microbial agent comprises a strain selected from the genus Bacillus or the genus Pseudomonas.

6. The method according to claim 1, wherein: The synergistic repair mixture in step (4) further comprises modified biochar. Preferably, the amount of the modified biochar added is 0.5-1% based on the amount of the synergistic repair mixture added.

7. The method according to claim 1, characterized in that In the step (4), the mass ratio of the target compost product, the saline-alkali soil to be repaired, and the AMF expanded body obtained in the step (3) is 1-2:8-9:0.2-0.

5.

8. The method according to claim 1, wherein: In step (5), the salt-alkali tolerant crops are selected from one or more of cotton, sunflower, sweet sorghum, quinoa or alfalfa.

9. The method according to claim 1, wherein: In the step (5), rhizosphere signal molecules are applied during the growth of the plants.

10. The method according to claim 9, characterized in that: The rhizosphere signal molecule is selected from one or more of strigolactone analogs or flavonoids.

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