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Soil microbial communities associated with the rhizosphere of cucumber under

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土壤化学中量元素

土壤化学中量元素
Forms
S is absorbed by plant roots almost exclusively as sulfate(SO4-2) and Thiosulfate(S2O3-2) S is absorbed by plant leaves quantities as SO2
Gramineae < Leguminosae < Cruciferae
Forms and Functions of S in Plants
Forms
leaves
SO4-2
Other tissues -S-S -SH
Forms and Functions of S in Plants
Functions
S is required for synthesis of S-containing amion acids cystine, cysteine, and methionine, which are essential components of protein that comprise about 90% of the S in plants.
possible mechanisms of SO4-2 adsorption include:
Fe/Al
Al(OH)x
OM
Forms of S in Soil
Factors Affecting SO4-2 Adsorption/Desorption(7.) Clay Minerals. SO4-2 adsorption increases with clay content. Hydrous Oxide. Fe/Al oxides are responsible for most SO4-2 adsorption in soil. Soil OM. Increasing soil OM content increases SO4-2 adsorptain potential.

APPLIED SOIL ECOLOGY投稿说明

APPLIED SOIL ECOLOGY投稿说明

Applied Soil Ecology addresses the role of soil organisms and their interactions in relation to: agricultural productivity, nutrient cycling and other soil processes, the maintenance of soil structure and fertility, the impact of human activities and xenobiotics on soil ecosystems and bio(techno)logical control of soil-inhabiting pests, diseases and weeds. 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红树林潜在生物多样性

红树林潜在生物多样性

Indian Journal of Marine SciencesVol. 38(2), June 2009, pp. 249-256Potential microbial diversity in mangrove ecosystems:A reviewK. Sahoo, & N.K. DhalInstitute of Minerals and Materials Technology (Council of Scientific and Industrial Research) Bhubaneswar-753013, Orissa, India[E.mail:nkdhal@immtbhu.res.in]Received 11 March 2008; revised 17 October 2008Mangroves provide a unique ecological niche to different microbes which play various roles in nutrient recycling as well as various environmental activities. Mangrove forests are large ecosystems distributed in 112 countries and territories comprising a total area of about 181,000 km2 is over a quarter of the total coastline of the world. The highly productive and diverse microbial community living in mangrove ecosystems continuously transforms nutrients from dead mangrove vegetation into sources of nitrogen, phosphorous and other nutrients that can be used by the plants and in turn the plant-root exudates serve as a food source for the microbes. Analysis of microbial biodiversity from these ecosystems will help in isolating and identifying new and potential microorganisms having high specificity for various applications.The present study consists literature on diversity of predominant microbes such as bacteria, fungi and actinomycetes from mangrove ecosystems.Keywords: mangrove, actinomycetes, nutrient recycling and diversity.IntroductionMangroves are coastal wetland forests mainly found at the intertidal zones of estuaries, backwaters, deltas, creeks, lagoons, marshes and mudflats of tropical and subtropical latitudes. The specific regions where mangrove plants grow are termed as “mangrove ecosystem”. Mangrove forests occupy several million hectares of coastal area worldwide and distributed in over 112 countries and territories comprising a total area of about 1,81,000 km2in over one fourth of the world's coastline1,2. According to Forest Survey of India (FSI)3, out of 4,87,100 ha of mangrove wetlands in India, nearly 56.7% (2,75,800 ha) is present along the east coast, and 23.5% (1,14,700 ha) along the west coast and the remaining 19.8% (96,600 ha) is found in the Andaman and Nicobar islands. The largest single area of mangroves in the world lies in the Bangladesh part of the Sunderbans, covering an area of almost 6,00,000 ha including waterways. There are about 6.9 million ha in the Indo-Pacific region, 3.5 million ha in Africa, 4.1 million ha in the Americas including the Caribbean. Mangroves also survive in some temperate zones but there is a rapid decrease in the number of species with increasing latitude4,5,6. Microbial Diversity in Mangrove ecosystems Although microbial diversity is one of the difficult areas of biodiversity research, extensive exploration is required for understanding the biogeography, community assembly and ecological processes which will for isolating and identifying new and potential microorganisms having high specificity for recalcitrant compounds7,8. The present review highlights on the diversity study of potential bacteria, fungi and actinomycetes in mangrove environments.BacteriaThe importance of microbially generated detritus in mangrove areas that acts as the major substrate for bacterial growth in mangrove ecosystems was outlined in a conceptual model by Bano et al9. The abundance and activities of bacteria are controlled by various physical and chemical factors such as tannin, leached from mangrove litter of the mangrove ecosystem. Increasing tannin concentration is associated with decreasing bacterial counts. Thus, tannin plays a role not only in keeping the bacterial counts low but also keeping the harmful activities of virulent pathogens down10.Nitrogen fixation in mangrove ecosystemNitrogen fixation is a process of conversion of gaseous forms of Nitrogen (N2) into combined_________________*Corresponding author:INDIAN J MAR SCI. VOL.38, No 2 JUNE 2009 250forms i.e. ammonia or organic nitrogen by some bacteria and cyanobacteria. Free living as well as symbiotic microbes known as diazotrophs which fix N2 into proteins. Nitrogen-fixing microorganisms can colonize in both terrestrial as well as marine environments. N2 fixation in mangrove sediments is likely to be limited by insufficient energy sources. The low rates of N2fixation by heterotrophic bacteria detected in marine water are probably due to lack of energy sources. Nitrogen fixation by heterotrophic bacteria can be regulated by specific environmental factors such as oxygen, combined nitrogen and the availability of carbon source to support energy requirement. Energy for N2fixation can also be derived from leaves and roots decomposed by nondiazotrophic microflora that colonize dead mangrove leaves11,12. Nitrogen-fixing bacteria such as members of the genera Azospirillum, Azotobacter, Rhizobium, Clostridium and Klebsiella were isolated from the sediments, rhizosphere and root surfaces of various mangrove species. Several strains of diazotrophic bacteria such as Vibrio campbelli, Listonella anguillarum, V. aestuarianus, and Phyllobacterium sp. were isolated from the rhizosphere of the mangroves in Mexico13. In a mangrove in Florida, biological N2fixation could supply up to 60% of the nitrogen requirement11. The main factors influencing N2 fixation are light intensity and water temperature14. It is also possible that microorganisms associated with Languncularia racemosa including Pseudomonas stutzeri15 could also be responsible for the fixation of atmospheric nitrogen16,17,18. N2fixing bacteria are efficient at using a variety of mangrove substrates despite differences in carbon content and phenol concentrations19. However, their abundance may be dependent on physical conditions and mangrove community composition. N2fixing Azotobacter, which can be used as biofertilizers, were abundant in the mangrove habitats of Pichavaram20. Two halotolerant N2fixing Rhizobium strains were isolated from root nodules of Derris scandens and Sesbania species growing in the mangrove swamps of the Sunderbans21. When the non N2 fixing bacteria were removed from the rhizosphere it was found that the N2fixing activity dropped, indicating that other rhizosphere bacteria could also contribute to the fixation process13. The non-N2 fixer, Staphylococcus sp., isolated from mangrove roots also promotes N2 fixation by Azospirillum brasilense22.Phosphate solubilising bacteriaPhosphate solubilizing bacteria which act as potential suppliers of soluble forms of phosphorus have a great advantage for mangrove plants. Certain bacteria exhibit high phosphatase activity, capable of solubilizing phosphate23. In an arid mangrove ecosystem in Mexico, nine strains of phosphate-solubilizing bacteria such as Bacillus amyloliquefaciens, B. atrophaeus, Paenibacillus macerans, Xanthobacter agilis, Vibrio proteolyticus, Enterobacter aerogenes, E. tay/orae, E. asburiae, and Kluyvera cryocrescens were isolated from black mangrove (Aviciena germinant) roots. Further three strains viz. B. licheniformis, Chryseomonas luteola and Pseudomonas stutzeri were isolated from white mangrove (Languncularia racemosa) roots. This is the only report of the phosphate-solubilizing capacity of bacteria belonging to the genera Xanthobacter, Kluyvera and Chryseomonas, and of their presence in mangrove roots. The mechanism responsible for phosphate solubilization, in at least six of the above bacterial species, probably involved production of organic acids. Some of the organic acids might act as chelators displacing metals from phosphate complexes15.Sulfate reducing BacteriaMangrove sediments are mainly anaerobic with an overlying thin aerobic sediment layer. Degradation of organic matter in the aerobic zone occurs principally through aerobic respiration whereas in the anaerobic layer decomposition occurs mainly through sulfate-reduction24,25. Sulfate reduction accounts for almost 100% of the total emission of CO2 from the sediment26. Sulfate-reducing bacteria isolated from a temperate coastal marine sediment from shallow, brackish water in Denmark could degrade up to 53% of the total organic matter27. In Goa’s mangroves, eight species of sulfate-reducing bacteria such as Desulfovibrio desulfuricans, Desulfovibrio desulfuricans aestuarii, Desulfovibrio salexigens, Desulfovibrio sapovorans, Desulfotomaculum orientis, Desulfotomaculum acetoxidans, Desulfosarcina variabilis, and Desulfococcus multivorans were isolated and tentatively classified within four different genera. These strains are nutritionally versatile and they have the ability to metabolize a wide range of simple compounds including lactate, acetate, propionate, butyrate, and benzoate. The ability to use several different substrates may allow these microbes to compete effectively for nutrients in the mangrove environment28. In mangrove sediments, availability of iron and phosphorus may depend on the activity of sulfate- reducing bacteria25.SAHOO & DHAL: MICROBIAL DIVERSITY IN MANGROVE ECOSYSTEMS 251All sediments (associated or not associated with the plants) in Florida's mangroves contained a significant population of sulfate reducing bacteria that were able to fix N211.Photosynthetic anoxygenic bacteriaPhotosynthetic anoxygenic bacteria use hydrogen sulfide (or other reduced inorganic sulfur) instead of water as an electron donor in the photosynthetic reaction. Photosynthetic bacteria of the mangrove sediments include two major groups viz., purple sulfur bacteria (family Chromatiaceae, strains belonging to Chromatium sp.) and purple non-sulfur bacteria (family Rhodospirillaceae, strains belonging to Rhodopseudomonas sp.). Sulfur rich mangrove ecosystems, which have mainly anaerobic soil environments, provide favorable conditions for the proliferation of these bacteria. It has been reported in few papers about the presence of anoxygenic photosynthetic bacteria in mangrove environments and one reason behind this may be that some of these bacteria are slow growers and difficult to handle in the laboratory. Nevertheless, representatives of the families Chromatiaceae (purple sulfur bacteria) and Rhodospirillaceae (purple nonsulfur bacteria) were found in Indian mangrove sediments29,30. The predominant bacteria in the mangrove ecosystem of Cochin (India) were identified as members of the genera Chloronema, Chromatium, Beggiatoa, Thiopedia, and Leucothiobacteri31,32. Large populations of Chromatium grew in enrichment cultures made of Florida's mangrove sediments. In mangroves on the coast of the Red Sea in Egypt, 225 isolates of purple nonsulfur bacteria belonging to ten species, representing four different genera, were identified. The strains were isolated from water, mud, and roots of Aviciena marina samples. Nine of the ten species inhabited the rhizosphere and root surface of the trees. The most common genera such as Rhodobacter and Rhodopseudomonas were detected in 73% and 80% of the samples respectively33. Some of the photosynthetic anoxygenic bacteria were also diazotrophic. Although there is yet no published evidence, one can hypothesize that photosynthetic anoxygenic bacteria, the predominant photosynthetic organisms in anaerobic environments, may contribute to the productivity of the mangrove ecosystems. Methanogenic BacteriaMethanogenic bacteria are probably an important component of the bacterial community in mangrove ecosystems. In an Indian mangrove ecosystem, the methanogenic bacteria population in the sediments fluctuated during the year from 3.6×102 to 1.1×105 cfug-1wet sediment, depending on temperature, pH, redox potential, and salinity of the water and sediments34. The presence of sulfate-reducing bacteria limits the proliferation of these bacteria35, a strain of the methanogenic bacterium, Methanococcoides methylutens36, and four strains of unidentified thermotolerant methanogenic bacteria37 were isolated from sediment of a mangrove forest. Methane may have been oxidized under anoxic conditions as occurred in hypersaline microbial mats38and anoxic marine sediment39. Another mangrove ecosystem cleared for aquaculture also showed significantly more methanodynamic activity (a dynamic system of methane production, oxidation, and emission)40. These results suggest that the potential of mangrove soils to emit methane was higher when there is anthropogenic activity41.A methanogenic bacterium, Methanococcoides methyJuteus, was isolated and characterized from the sediment of mangrove environment of Pichavaram, Southeast India42. Methanogenic bacteria were high during summer and pre-monsoon and low during monsoon and post-monsoon43.Enzyme producing bacteriaAbout 71% of bacterial strains produce L-asparaginase. It is an enzyme drug of choice used in combination therapy for treating acute lymphoblastic leukemia in children. Since extraction of L-asparaginase from mammalian cells is difficult, microorganisms have proved to be a better alternative for L-asparaginase extraction, thus facilitating its large scale production. Mashburn and Wriston successfully purified Escherichia coli L-asparaginase and demonstrated its tumouricidal activity. Halophilic bacteria (Halococcus) isolated from mangrove sediments, produce L-asparaginase44. Arylsulfatase, an important enzyme that participates in the metabolism of sulphuric acid esters, produced predominantly by Bacillus, followed by Vibrio. One hundred and eight strains of bacteria show chitin degrading activity45.FungiMangrove areas or mangals are home to a group of fungi called “manglicolous fungi”. These organisms are vitally important for nutrient cycling in these habitats46,47and are able to synthesize all theINDIAN J MAR SCI. VOL.38, No 2 JUNE 2009 252necessary enzymes to degrade lignin, cellulose, and other plant components48,49,50,51. Hyde listed 120 species from 29 mangrove forests around the world52. These included 87 Ascomycetes, 31 Deuteromycetes, and 2 Basidiomycetes. In mangrove communities, over a hundred species of fungi were identified. About 48 fungal species were found in decomposing Rhizophora debris in Pichavaram, South India53. Most of the studies involving fungi are of a descriptive nature, designed for taxonomic and inventory interests. Fungal hyphae are commonly found on and in decomposing mangrove leaves and wood. In a mangrove from the coast of the Indian Ocean, Hyde identified 67 species of marine fungi and found an additional 20 unidentified species associated with mangrove roots and dead branches54. In addition to degrading lignin and cellulose, the fungi Cladosporium herbarum, Fusarium moniliforme, Cirrenalia basiminuta, an unidentified hyphomycete and Halophytophthora vesicula isolated from the dead leaves of Rhizophora apiculata also show pectinolytic, proteolytic, and amylolytic activity55. These fungi begin the decomposition of vegetative material and thereby allow secondary colonization by bacteria and yeasts that further decompose the organic matter56. In an Indian mangrove, the first colonizers of fallen mangrove leaves were fungi and thraustochytrids (fungi-like unicellular protists). It is possible that both thraustochytrids and fungi tolerate high levels of phenolic compounds in the leaves of mangroves that inhibit the growth of other microorganisms57, Despite the great wealth of systematic information, there is a little knowledge about the role of mangrove fungi in nutrient recycling58. A few researchers have studied the physiology and biochemistry of manglicolous fungi. Many of the species produce interesting compounds. For example, most of the soil fungi produce lignocellulose-modifying exoenzymes like laccase55. Preussia aurantiaca synthesizes two new depsidones (Auranticins A and B) that display antimicrobial activity59.ActinomycetesActinomycetes play a quite important role in natural ecological system and they are also profile producers of antibiotics, antitumor agents, enzymes, enzyme inhibitors and immunomodifiers which have been widely applied in industry, agriculture, forestry and pharmaceutical industry. The actinomycetes population density is less common in marine sediments relative to terrestrial soils60. In the past, the research work on actinomycetes was mainly concentrated on that of common habitats. Actinomycetes resources under extreme environments (including extreme high and low temperature, extreme high or low pH, high salt concentration etc.) have received comparatively little attention from microbiologists. The mangrove environment is a potent source for the isolation of antibiotic-producing actinomycetes. An antibiotic compound-beta-unsaturated gama-lactone from Streptomyces grisebrunneus, showing wide-range anti-microbial activity, was isolated and identified61. Besides this, the Streptomycetes produce cellulase that degrades cellulolytic waste materials62. The actinomycetes, inhabiting the sediments and molluscs of Vellar estuary are the potential sources of extracellular enzymes involved in the marine environment. This would suggest that bioprospecting of enzymes of industrial needs can be made from these marine actinomycetes63. There is a scope for the use of S. galbus as an ideal organism for the industrial production of extracellular L-glutaminase and this can be pursued further64. Different strains of actinomycetes isolated from the sediments of the Vellar estuary, viz. S. alboniger, S. vastus, S. violaceus, S. moderatus and S. aureofasciculus elucidates interesting information on the antibiotic producing properties and possesses bioactive properties and can be utilized in future for isolating the bioactive compounds for human walefare65. It has been reported that S.albidoflavus has antitumor properties isolated from the Pichavaram mangrove environment66. Actinopolyspora sp. isolated from the west coast of India, showed good antimicrobial activity against gram positive bacteria like S. aureus, S. epidermis, B. subtilis and fungi such as A. niger, A. fumigatus, A. f1avus, F. oxysporum, Penicillium sp. and Trichoderma sp. where as it did not show any antimicrobial activity against gram-negative bacteria such as E. coli, P. aeruginosa, S. marcescens, E. aerogens and fungi like C. albicans and Cryptococcus Sp.67.Other potential usefulness of microbes from mangrove ecosystemsBesides these above microbes, there is the presence of other potential microbes in mangrove ecosystems on which much studies has not been done yet. In addition to processing nutrients, mangrove bacteria may also help in processing industrial wastes. Iron-reducing bacteria were common in mangrove habitatsSAHOO & DHAL: MICROBIAL DIVERSITY IN MANGROVE ECOSYSTEMS 253in some mining areas68. Eighteen bacterial isolates that metabolize waste drilling fluid were collected from a mangrove swamp in Nigeria69. Interestingly, four additional bacterial strains isolated from the same swamp depress growth rates of Staphylococcus and Pseudomonas species and could, therefore, decrease normal rates of organic decomposition70. Other mangrove bacteria are parasitic or pathogenic. Bdellovibrios capable of parasitizing Vibrio sp. are common in an Australian mangrove habitat71. Also in Australia, Bacillus thuringiensis, which showed insecticidal activity against mosquito larvae of Anopheles maculatus, Aedes aegypti and Culex quinquefasciatus, has been isolated from mangrove sediments72,73. Nine species of purple non-sulfur bacteria have also been found in mangroves of Egypt33. Growth of the purple sulfur bacteria in these habitats was limited by low light and sulfide. Certain bacterial strains such as Pseudomonas mesophilica, P. caryophylls and Bacillus cereus exhibit magnetic behaviour which may be called magnetobacteria isolated from mangrove sediments of Pichavaram, Southeast India74. The total heterotrophic bacterial counts in the degrading materials such as polythene bags and plastic cups were recorded up to higher in comparison with fungi in an Indian mangrove soil. The microbial species found associated with the degrading materials were identified as five Gram positive and two Gram negative bacteria, and eight fungal species of Aspergillus. The species that were predominant were Streptococcus, Staphylococcus, Micrococcus (Gram+ve), Moraxella, and Pseudomonas (Gram-ve) and two species of fungi (Aspergillus gloocus and A. niger). Among the bacteria, Pseudomonas sp. degraded 20.54% of polythene and 8.16% of plastics in one-month period. Among the fungal species, Aspergillus glaucus degraded 28.80% of polythene and 7.26% of plastics in one-month period. This work reveals that the mangrove soil is a good source of microbes capable of degrading polythene and plastics75. Hydrocarbon-utilizing microorganisms were isolated by enrichment techniques from soil and water samples collected from an oil spill site in the Niger delta area of Nigeria. The isolates included species of Micrococcus, Pseudomonas, Bacillus, Aeromonas, Serratia, Proteus, Penicillium, Aspergillus, Candida, Geotrichum and Rhizopus76. Amanchukwu et al. demonstrated similarly that lower concentrations (1.5-6.0%) of hydrocarbons were highly utilized by Schizosaccharomyces pombe than higher concentrations (12%)77. Mangrove reforestation and conservation using Plant Growth Promoting Bacteria (PGPB) Mangrove greenbelts were known to offer some protection against destructive ocean events, such as tsunamis and tropical cyclones, but they have not always been valued for that function. It may be possible to use PGPB to speed up the development of mangrove plantlets for reforestation of the damaged areas or even to create artificial mangrove wetlands out of wastelands. PGPB promotes the plant growth by mechanisms such as N2fixation, phosphate solubilization, phytohormone production, siderophore synthesis, or biocontrol of phytopathogens78,79,80,81. PGPB specific to mangrove ecosystems are unknown. Scanning electron microscope studies revealed that, in seawater in vitro, a dense population of Azospirillum brasilense and A. alopraeferens successfully colonized black mangrove roots, establishing an association with the plant within four days82. Inoculation of black mangrove plantlets with the cyanobacterium M. chthonoplastes yielded copious root colonization in a thick mucilaginous sheath which resulted in an increased in N z fixation83 and nitrogen accumulation in inoculated seedlings84. Many studies of plant-growth promotion by beneficial bacteria have reported the advantage of using mixed cultures of microorganisms over pure cultures80,81. It can be concluded that PGPB will effectively promote the growth of mangrove plantlets which will be helpful in mangrove reforestation.ConclusionMangrove ecosystems provide shelter and nurturing sites for many marine microorganisms. Conservation strategies for mangroves should consider the ecosystem as a biological entity, which includes all the physical, chemical, and ecological processes that maintain productive mangroves. Despite of various studies on the biogeography, botany, zoology, ichthyology, environmental pollution and economic impact of mangroves, little is known about the activities of microbes in mangrove waters and sediments. Due to the presence of rich source of nutrients mangroves are called the homeland of microbes. Extensive exploration, identification, isolation and screening is suggested in search of new leads for microbial drugs. AcknowledgementThe authors are thankful to the Director, Institute of Minerals and Materials Technology (formerly RRL), Bhubaneswar for his valuable comments and valid suggestions during manuscript preparation.INDIAN J MAR SCI. VOL.38, No 2 JUNE 2009254References1 Alongi D M, Present state and future of the world'smangrove forests. Environ. 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Microbiol, 35 (1978) 567-575.12 Zuberer D A & Silver W S, N 2-fixation (acetylenereduction) and the microbial colonization of mangrove roots.New Phytol., 82 (1979) 467-471.13 Holguin G, Guzman A & Bashan Y, Two new nitrogen-fixing bacteria from the rhizosphere of mangrove trees: theirisolation, identification and in vitro interaction withrhizosphere Staphylococcus sp. FEMS Microbiol. Ecol., 101(3) (1992) 207-216.14 Toledo G, Bashan Y & Soeldner A, Cyanobacteria and blackmangroves in Northwestern Mexico: colonization, anddiurnal and seasonal nitrogen fixation on aerial roots. Can. J.of Microbiol., 41 (1995a) 999-1011.15 Vazquez P, Holguin G, Puente M E, Lopez-Cortes A &Bashan Y, Phosphate-solubilizing microorganisms associatedwith the rhizosphere of mangroves in a semiarid coastallagoon. Bioi. Fertil Soils, 30 (2000) 460-468.16 Krotzky A & Werner D, Nitrogen fixation in Pseudomonasstutzeri. Arch. Microbiol., 147 (1987) 48-57.17 Alongi D M, Boto K G & Robertson A I, Nitrogen andPhosphorus cycles. In Robertson A I. & D. M. Alongi (eds),Tropical Mangrove Ecosystems. Washington DC: Ameri.Geophy. Uni., 41 (1992) 251-292.18 Alongi D M, Christoffersen P & Tirendi F, The influence offorest type on microbial-nutrient relationships in tropicalmangrove sediments. J. Exp. Mar. Biol. Ecol., 171 (1993)201-223.19 Pelegri S P & Twilley R R, Heterotrophic nitrogen fixation (acetylene reduction) during leaf-litter decomposition of two mangrove species from South Florida, USA. Mar. Biol, 131 (1) (1998) 53-61. 20 Ravikumar S, Nitrogen-fixing azotobacters from the mangrove habitat and their utility as bio-fertilizers. Ph.D. thesis, Annamalai University, India. (1995) 120. 21 Sengupta A, & Chaudhuri S, Halotolerant Rhizobium strains from mangrove swamps of the Ganges River Delta. Indian J. Microbiol., 30 (1990) 483-484. 22 Holguin G & Bashan Y, Nitrogen-fixation by Azospirillum brasilense is promoted when co-cultured with a mangrove rhizosphere bacterium (Staphylococcus sp.). Soil Biol. and Biochem. 28 (12) (1996) 1651-1660. 23 Sundararaj V , Dhevendran K, Chandramohan D & Krishnamurthy K, Bacteria and primary production. Indian J. Mar. Sci. 3 (1974) 139-141. 24 Nedwell D B, Blackburn T H & Wiebe W J, Dynamic nature of the turnover of organic carbon, nitrogen and sulphur in the sediments of a Jamaican mangrove forest. Mar. Ecol. Prog. Ser., 110 (1994) 223-231. 25 Sherman R E, Fahey T J & Howarth R W, Soil-plant interactions in a neotropical mangrove forest: iron, phosphorus and sulfur dynamics. Oecologia, 115 (1998) 553-563. 26 Kristensen E, Holmer M & Bussarawit N, Benthic metabolism and sulfate reduction in a south-east Asian mangrove swamp. Mar. Ecol Prog. Ser. 73 (1991) 93-103. 27 Jorgensen B B, The sulfur cycle of a coastal marine sediment (Limfjorden, Denmark). 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红根病感染对橡胶树根际土壤微生物群落和代谢物的影响

红根病感染对橡胶树根际土壤微生物群落和代谢物的影响

热带农业科技Tropical Agricultural Science&Technology2024,47(1)：56-62DOI:10.16005/ki.tast.2024.01.011红根病感染对橡胶树根际土壤微生物群落和代谢物的影响戴利铭，李岚岚，刘一贤，施玉萍，蔡志英*（云南省热带作物科学研究所/云南省天然橡胶可持续利用研究重点实验室（筹）/天然橡胶良种选育与栽培技术国家地方联合工程研究中心，云南景洪666100）摘要：：以景洪小勐养植胶区的健康和发病橡胶树根际土壤为研究对象，通过高通量测序和代谢组摘要技术对土壤进行研究，以期揭示感染红根病后橡胶树根际土壤中微生物和代谢物的变化情况。

结果发现健康和发病橡胶树根际土壤微生物群落结构及其土壤代谢物成分有很大差异。

在发病土壤中酸杆菌门的相对丰度最高，比健康土壤高5.11%，放线菌门和变形菌门相对丰度小于健康土壤；在属分类水平，健康土壤中根瘤菌属相对丰度最高，其次为链霉菌属，而发病土壤中链霉菌属相对丰度最高；KEGG功能注释发现发病土壤和健康土壤在碳水化合物代谢、氨基酸代谢方面无明显差异，NOG数据库注释发现发病土壤中ABC转运蛋白和丝氨酸、苏氨酸蛋白激酶均高于正常土壤；利用GC-MS非靶向代谢组学技术测定发现，与健康土壤相比，发病土壤中的蜡酸、甘油磷酸酯、胆固醇、胆甾烷-3,5,6-三醇、富马酸、豆甾醇、N-环己基甲酰氨等7个物质含量显著增加，而花生四烯酸和N-乙酰基-5-羟色胺含量显著降低。

关键词：：橡胶树；红根病；土壤微生物；代谢物关键词中图分类号：S794.107；S763.7文献标识码：A文章编号：1672-450X（2024）01-0056-07Effect of Red Root Disease Infection on Microbial Communities and Metabolites in Rhizosphere Soil of Rubber TreeDAI Liming,LI Lanlan,LIU Yixian,SHI Yuping,CAI Zhiying*Yunnan Institute of Tropical Crops/Yunnan Key Laboratory of Sustainable Utilization Research on Rubber Tree/National and Local Joint Engineering Research Center of Breeding and Cultivation Technology of Rubber Tree,Jinghong666100,China Abstract:The healthy and diseased soils in rubber planting area of Mengyang of Jinghong were taken as tested sample,high-throughput sequencing and metabolic group techniques were used to study the changes of microorganisms and metabolites in the rhizosphere soil of rubber trees infected with red root disease.It is found that there is significant difference in the rhi-zosphere soil microbial community structure and soil metabolite composition in two soils.Acidobacteria in affected soil was the phylum with the highest relative abundance,its abundance was5.11%higher than that of in healthy soil,and the abundance of Actinomycetes and Proteobacteria was lower than that of in healthy soil.Based on the relative abundance of subordinate classification levels,the relative abundance of healthy soil is the highest in Rhizobium,followed by Streptomy-ces;The highest relative abundance in the affected soil is Streptomyces.KEGG functional annotation showed that there was no significant difference in carbohydrate metabolism and amino acid metabolism between affected soil and healthy soil.The annotation of NOG database found that ABC transporter and serine Threonine protein kinase were higher in affect-ed soil than in normal soil.The metabolic components of susceptible and healthy rhizosphere soil were determined by GC-MS non-targeted pared with healthy soil,the contents of wax acid,glycerol phosphate,cholesterol,————————————收稿日期：2023-08-08基金项目：云南省热带作物科技创新专项资金项目（RF2023-7）；云南省农业联合专项面上项目（202301BD070001-260）作者简介：戴利铭（1990－），女，助理研究员，硕士，研究方向为植物保护与微生物利用。

植物根际微生物研究进展

植物根际微生物研究进展

植物根际微生物研究进展作者：高鹤来源：《农业科技与装备》2021年第01期摘要：根际微生物是植物根系环境中特有的微生物群。

分析植物类型、土壤类型、栽培管理制度等因素对根际微生物群落多样性和群落结构的影响，阐述根际微生物对植物生长发育的积极作用，以期为进一步研究与利用根际微生物来促进作物优质高产提供参考。

关键词：植物;根际微生物;影响因素中图分类号：S154.3 文献标识码：A 文章编号：1674-1161（2021）01-0024-03根际微生物是指在植物根系生长发育过程中，根际逐渐形成的其特有的微生物群落。

根际微生物的活动及代谢产物均能直接或间接影响根系对营养物质的吸收、传递以及生长发育，同时在根际土壤物质转化中发挥重要作用。

因此，根际土壤在物理、化学及生物学特性上均不同于原土体，它是植物、土壤、微生物及环境条件相互作用的场所和特殊的微生态系统，是物质进入根系参与物质循环的重要门户，是植物产生化感物质的媒介，更是功能性微生物的主要活动场所。

在根际，微生物与植物根系相互影响、相互制约，形成了复杂的三边关系。

植物类型、土壤类型、有机物料的施入及化学药剂的使用等因素都会对根际微生物群落结构产生影响，但对根际微生物起决定性影响的因素与土壤自身理化性质和植物生长有直接关系。

1 植物对根际微生物的影响植物特别是其根系是根际微生物生长与繁殖的主要营养来源，对根际微生物群落多样性及群落结构具有重要影响。

研究根际土壤微生物群落的核心问题就是研究植物与土壤微生物之间的关系。

根际微生物群落结构的变化不仅表现为根际土壤微生物数量明显高于非根际土壤，在结构和功能上也与非根际土壤有较大差异。

根系脱落物、分泌物等物质的存在是维持根际微生物数量和活性的主要因素。

随着植物生长年份的增加，大量不同的根际沉积物累积，为以此类物质为能源物质的根际微生物提供了充足的养分。

植物类型的差异决定着根际微生物群落结构的差异。

朱斌等人对初夏季节宝华山自然保护区中处于不同演替阶段的次生裸地、纯盐肤木林及青冈—栓皮栎混交林下的土壤微生物进行调查发现，纯盐肤木林内细菌最多，混交林次之，次生裸地最少。

根际-微生物-重金属互作关系浅析

根际-微生物-重金属互作关系浅析

植物-根际微生物-重金属互作关系浅析摘要：随着社会经济的发展，农业污染所引发的环境健康问题日益收到人们的关注。

土壤-植物-微生物作为农业生态系统营养和能量循环最重要链条之一，各种因子间的互作关系及各种生态因子受到的影响因素被广泛的研究并报道。

外源重金属作为当前普遍污染源对土壤-植物-微生物会干扰原有系统的平衡并产生效应，本文对近年来有关植物-根际微生物-重金属体系的相关研究成果作系统综述。

关键词：植物根际微生物重金属互作关系土壤是地球上生命活动最活跃的场所，是自然界物质循环和能量流动的关键枢纽。

微生物作为土壤健康状况和肥力水平的生物学指标[1]，受到土壤本身自然条件和人为等多种因素的影响。

在植物-土壤-微生物生态体系中，根际是植物与外界环境互作的重要门户[2]，对外界环境变化具有一定的响应。

随着现代社会的快速发展，重金属污染已成为全球性的问题。

土壤成为重金属污染物的源与汇，由其引发的食品安全问题已成为土壤科学、环境科学、食品科学等相关学科关注的热点。

国内外学者对根际-微生物-重金属这一生物小循环做了大量研究[3-6]，其研究结果对于改善生态环境、提高作物品质和保障食品安全具有重要的作用。

1 植物根系对土壤微生物及重金属的影响1.1 植物根系对土壤微生物的影响根系是作物汲取矿质营养元素、自身代谢原料的重要器官，同时也排泄代谢产物、响应外界环境的关键部位，而这一系列过程大多在土壤中完成。

土壤微生物群落受温度pH值、含水率、可溶盐含量、有机质含量、氮、磷、钾等营养盐、Fe、Mn等微生物生长所需的微量元素等理化性质的影响[7]。

根系一方面通过分泌有机酸等物质从化学性质上影响根际微生物种群和酶活性[8]，环境胁迫下的根际甚至通过分泌一些特殊物质来适应环境，从而导致微生物群落结构的演替[9]。

另一方面根系通过生长（即根系形态）打破土壤原有的结构平衡而改变土壤通透状况，分泌的有机酸等代谢产物也能促进土壤团聚体的形成。

两种处理对西洋参根际土壤理化性质及真菌群落的影响

㊀山东农业科学㊀２０２３ꎬ５５(２):８４~９１ＳｈａｎｄｏｎｇＡｇｒｉｃｕｌｔｕｒａｌＳｃｉｅｎｃｅｓ㊀ＤＯＩ:１０.１４０８３/ｊ.ｉｓｓｎ.１００１－４９４２.２０２３.０２.０１２收稿日期:２０２２－０７－２６基金项目:陕西省区域创新能力引导计划项目(２０２０ＱＦＹ１２－０６)ꎻ秦巴生物资源与生态环境国培重点实验室项目(ＳＬＧＰＴ２０１９ＫＦ０４－０３)作者简介:舒瑜(１９９８ )ꎬ女ꎬ硕士研究生ꎬ研究方向为西洋参连作障碍ꎮＥ－ｍａｉｌ:ｓｈｕｙｕ１９９８０３２３＠１６３.ｃｏｍ通信作者:蒋景龙(１９８０ )ꎬ男ꎬ博士ꎬ副教授ꎬ主要从事西洋参连作障碍研究ꎮＥ－ｍａｉｌ:ｊｉａｎｇｊｉｎｇｌｏｎｇ５１１＠１６３.ｃｏｍ两种处理对西洋参根际土壤理化性质及真菌群落的影响舒瑜ꎬ蒋景龙ꎬ陈德经ꎬ李丽ꎬ董艳鑫(陕西理工大学生物科学与工程学院/陕西省催化基础与应用重点实验室ꎬ陕西汉中㊀７２３０００)㊀㊀摘要:本试验通过西洋参根水提液(ＧＴ)和连作４年西洋参土壤浸提液(ＳＴ)定期浇灌西洋参幼苗ꎬ研究两种处理对西洋参幼苗生长及土壤理化性质和真菌群落的影响ꎮ结果表明ꎬ与ＣＫ组相比ꎬＧＴ和ＳＴ组死苗率明显升高ꎻＧＴ组碱解氮和速效钾含量㊁转化酶和脲酶活性显著上升ꎬｐＨ值和铵态氮含量均显著下降ꎻＳＴ组ｐＨ值和速效磷㊁铵态氮含量显著下降ꎬ碱解氮含量显著上升ꎮ利用ＩｌｌｕｍｉｎａＭｉｓｅｑ测序ꎬ共获得高质量序列７６８２６２条ꎬＰＣＡ分析显示３组样品真菌结构存在显著差异ꎮ与ＣＫ组相比ꎬＧＴ组和ＳＴ组Ｃｈａｏ１指数和ＡＣＥ指数下降ꎬＳｈａｎｎｏｎ指数和Ｓｉｍｐｓｏｎ指数升高ꎮ在门水平ꎬ被孢霉门(Ｍｏｒｔｉｅｒｅｌｌｏｍｙｃｏｔａ)㊁子囊菌门(Ａｓｃｏｍｙｃｏ￣ｔａ)㊁壶菌门(Ｃｈｙｔｒｉｄｉｏｍｙｃｏｔａ)和担子菌门(Ｂａｓｉｄｉｏｍｙｃｏｔａ)为３组样品中的差异菌门ꎮ两处理明显抑制了西洋参幼苗的生长ꎬ并导致根际土壤理化性质和真菌群落的变化ꎬ为进一步阐明西洋参连作障碍产生机理提供了依据ꎮ关键词:西洋参ꎻ连作障碍ꎻ 微生物群落ꎻ土壤理化性质ꎻ高通量测序中图分类号:Ｓ５６７.５＋３:Ｓ１５４.４㊀㊀文献标识号:Ａ㊀㊀文章编号:１００１－４９４２(２０２３)０２－００８４－０８ＥｆｆｅｃｔｓｏｆＴｗｏＴｒｅａｔｍｅｎｔｓｏｎＰｈｙｓｉｃｏｃｈｅｍｉｃａｌＰｒｏｐｅｒｔｉｅｓａｎｄＦｕｎｇａｌＣｏｍｍｕｎｉｔｙｉｎＲｈｉｚｏｓｐｈｅｒｅＳｏｉｌｏｆＰａｎａｘｑｕｉｎｑｕｅｆｏｌｉｕｓＳｈｕＹｕꎬＪｉａｎｇＪｉｎｇｌｏｎｇꎬＣｈｅｎＤｅｊｉｎｇꎬＬｉＬｉꎬＤｏｎｇＹａｎｘｉｎ(ＳｃｈｏｏｌｏｆＢｉｏｌｏｇｉｃａｌＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇꎬＳｈａａｎｘｉＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙ/ＳｈａａｎｘｉＰｒｏｖｉｎｃｉａｌＫｅｙＬａｂｏｒａｔｏｒｙｏｆＣａｔａｌｙｔｉｃＦｏｕｎｄａｔｉｏｎａｎｄＡｐｐｌｉｃａｔｉｏｎꎬＨａｎｚｈｏｎｇ７２３０００ꎬＣｈｉｎａ)Ａｂｓｔｒａｃｔ㊀ＩｎｔｈｉｓｓｔｕｄｙꎬＰ.ｑｕｉｎｑｕｅｆｏｌｉｕｓｓｅｅｄｌｉｎｇｓｗｅｒｅｒｅｇｕｌａｒｌｙｔｒｅａｔｅｄｗｉｔｈｉｔｓｒｏｏｔｗａｔｅｒｅｘｔｒａｃｔ(ＧＴ)ａｎｄｒｈｉｚｏｓｐｈｅｒｅｓｏｉｌｅｘｔｒａｃｔ(ＳＴ)ｆｒｏｍ４￣ｙｅａｒｃｏｎｔｉｎｕｏｕｓｃｒｏｐｐｉｎｇｆｉｅｌｄｓꎬｒｅｓｐｅｃｔｉｖｅｌｙꎬｔｏａｎａｌｙｚｅｔｈｅｉｒｅｆｆｅｃｔｓｏｎｓｅｅｄｌｉｎｇｇｒｏｗｔｈꎬｓｏｉｌｐｈｙｓｉｃａｌａｎｄｃｈｅｍｉｃａｌｐｒｏｐｅｒｔｉｅｓａｎｄｆｕｎｇａｌｃｏｍｍｕｎｉｔｙ.ＴｈｅｒｅｓｕｌｔｓｓｈｏｗｅｄｔｈａｔｃｏｍｐａｒｅｄｗｉｔｈｇｒｏｕｐＣＫꎬｔｈｅｓｅｅｄｌｉｎｇｍｏｒｔａｌｉｔｙｉｎｇｒｏｕｐＧＴａｎｄＳＴｗａｓｓｉｇｎｉｆｉｃａｎｔｌｙｉｎｃｒｅａｓｅｄꎻｔｈｅａｌｋａ￣ｌｉｈｙｄｒｏｌｙｚａｂｌｅＮａｎｄａｖａｉｌａｂｌｅＫｃｏｎｔｅｎｔｓａｎｄｔｈｅｉｎｖｅｒｔａｓｅａｎｄｕｒｅａｓｅａｃｔｉｖｉｔｉｅｓｉｎｇｒｏｕｐＧＴｉｎｃｒｅａｓｅｄｓｉｇｎｉｆｉ￣ｃａｎｔｌｙꎬｗｈｉｌｅｔｈｅｐＨｖａｌｕｅａｎｄａｍｍｏｎｉｕｍＮｃｏｎｔｅｎｔｄｅｃｒｅａｓｅｄｓｉｇｎｉｆｉｃａｎｔｌｙꎻｔｈｅｐＨｖａｌｕｅａｎｄｔｈｅｃｏｎｔｅｎｔｏｆａｍｍｏｎｉｕｍＮａｎｄａｖａｉｌａｂｌｅＰｄｅｃｒｅａｓｅｄｓｉｇｎｉｆｉｃａｎｔｌｙｉｎｇｒｏｕｐＳＴꎬｗｈｉｌｅｔｈｅａｌｋａｌｉ￣ｈｙｄｒｏｌｙｚｅｄＮｃｏｎｔｅｎｔｉｎ￣ｃｒｅａｓｅｄｓｉｇｎｉｆｉｃａｎｔｌｙ.Ａｔｏｔａｌｏｆ７６８２６２ｈｉｇｈ￣ｑｕａｌｉｔｙｓｅｑｕｅｎｃｅｓｗｅｒｅｏｂｔａｉｎｅｄｂｙＩｌｌｕｍｉｎａＭｉｓｅｑｓｅｑｕｅｎｃｉｎｇꎬａｎｄｔｈｅＰＣＡａｎａｌｙｓｉｓｓｈｏｗｅｄｓｉｇｎｉｆｉｃａｎｔｄｉｆｆｅｒｅｎｃｅｓｉｎｆｕｎｇａｌｓｔｒｕｃｔｕｒｅｏｆｔｈｅｔｈｒｅｅｇｒｏｕｐｓ.ＴｈｅＣｈａｏ１ａｎｄＡＣＥｉｎｄｅｘｅｓｄｅｃｒｅａｓｅｄｉｎｇｒｏｕｐＧＴａｎｄＳＴꎬａｎｄｔｈｅＳｈａｎｎｏｎａｎｄＳｉｍｐｓｏｎｉｎｄｅｘｅｓｉｎｃｒｅａｓｅｄｃｏｍｐａｒｅｄｗｉｔｈｇｒｏｕｐＣＫ.ＡｔｐｈｙｌｕｍｌｅｖｅｌꎬＭｏｒｔｉｅｒｅｌｌｏｍｙｃｏｔａꎬＡｓｃｏｍｙｃｏｔａꎬＣｈｙｔｒｉｄｉｏｍｙｃｏｔａａｎｄＢａｓｉｄｉｏｍｙｃｏｔａｗｅｒｅｔｈｅｄｉｆ￣ｆｅｒｅｎｔｐｈｙｌａｉｎｔｈｅｔｈｒｅｅｇｒｏｕｐｓ.ＩｎｃｏｎｃｌｕｓｉｏｎꎬｔｈｅｔｗｏｔｒｅａｔｍｅｎｔｓｓｉｇｎｉｆｉｃａｎｔｌｙｉｎｈｉｂｉｔｅｄｔｈｅｇｒｏｗｔｈｏｆＰ.ｑｕｉｎ￣ｑｕｅｆｏｌｉｕｓ㊀ｓｅｅｄｌｉｎｇｓａｎｄｃａｕｓｅｄｃｈａｎｇｅｓｉｎｐｈｙｓｉｃｏｃｈｅｍｉｃａｌｐｒｏｐｅｒｔｉｅｓａｎｄｆｕｎｇａｌｃｏｍｍｕｎｉｔｉｅｓｏｆｒｈｉｚｏｓｐｈｅｒｅｓｏｉｌꎬｗｈｉｃｈｃｏｕｌｄｐｒｏｖｉｄｅａｂａｓｉｓｆｏｒｆｕｒｔｈｅｒｅｌｕｃｉｄａｔｉｎｇｔｈｅｍｅｃｈａｎｉｓｍｏｆｃｏｎｔｉｎｕｏｕｓｃｒｏｐｐｉｎｇｏｂｓｔａｃｌｅｓｏｆＰ.ｑｕｉｎｑｕｅｆｏｌｉｕｓ.Ｋｅｙｗｏｒｄｓ㊀ＰａｎａｘｑｕｉｎｑｕｅｆｏｌｉｕｓＬ.ꎻＣｏｎｔｉｎｕｏｕｓｃｒｏｐｐｉｎｇｏｂｓｔａｃｌｅꎻＭｉｃｒｏｂｉａｌｃｏｍｍｕｎｉｔｙꎻＳｏｉｌｐｈｙｓｉｃｏ￣ｃｈｅｍｉｃａｌｐｒｏｐｅｒｔｉｅｓꎻＨｉｇｈ￣ｔｈｒｏｕｇｈｐｕｔｓｅｑｕｅｎｃｉｎｇ㊀㊀西洋参(ＰａｎａｘｑｕｉｎｑｕｅｆｏｌｉｕｓＬ.)别名美国花旗参ꎬ五加科多年生草本植物ꎬ有 绿色黄金 之称ꎬ原产于美国和加拿大[１]ꎮ２０世纪８０年代引入中国ꎬ并逐渐在陕西留坝㊁山东威海和东北吉林等地大规模栽培[２]ꎮ目前西洋参栽培时连作障碍问题极其严重ꎬ导致西洋参生长不良ꎬ严重减产ꎮ连作障碍是指同一块耕地不能连续种植相同作物的现象ꎬ主要与土壤理化性质的改变㊁化感自毒作用和土壤微生物的区系变化三大因素有关[３]ꎬ且三者之间相互影响ꎮ半夏随其重茬次数增多ꎬ可溶性蛋白增加ꎬ土壤全氮㊁全磷和碱解氮含量降低ꎬ微生物群落结构趋于简单ꎬ且致病菌增多ꎬ有益菌减少[４]ꎮ根际微生物菌群的组成可对植物生长发育产生影响ꎬ植物亦能通过调节ｐＨ值㊁土壤养分和根系结构来塑造它们自己的根际微生物群落[５]ꎮ真菌是土壤微生物中种类和数量最多的类群之一ꎬ在与植物互作方面发挥着一定的生态作用ꎬ有些真菌可以分解植物残渣ꎬ为植物提供营养ꎻ有些真菌会引起植物病害ꎬ影响植物生长[６]ꎮ不同年限的植物根际微生物结构也有差异ꎬ且微生物数量随种植时间而降低ꎮ土壤中微生物种类复杂且大多数不能在条件培养基上生长ꎬ末端限制性片段长度多态性分析(Ｔ－ＲＦＬＰ)㊁变性梯度凝胶电泳(ＤＧＧＥ)㊁单链构象多态性分析(ＳＳＣＰ)以及实时定量ＰＣＲ等传统研究土壤微生物群落多样性和组成的方法不足以获取全面的微生物群落信息ꎮ随着方法的进步ꎬ高通量测序技术已经成为分析微生物类群更全面㊁更准确㊁灵敏度更高的工具[７]ꎮ袁源等[８]采用高通量测序技术研究连作覆土下灵芝(ＧａｎｏｄｅｒｍａｌｕｃｉｄｕｍＫａｒｓｔ)真菌群落变化ꎬ发现随着连作年限的增加ꎬ真菌多样性逐年降低ꎮＭｉａｏ等[６]对２年生健康三七(Ｐａｎａｘｎｏｔｏｇｉｎｓｅｎｇ)的根际真菌群落进行高通量测序分析ꎬ发现接合菌属和子囊菌属为优势菌群ꎮ董艳鑫等[９]证明西洋参根水提液和重茬土壤浸提液对西洋参种子萌发及幼苗生理存在显著影响ꎬ表明其中可能存在某些化感物质可影响土壤微生物的类群㊁数量和植物自身生长发育ꎮ很多学者研究表明ꎬ相对于西洋参水提液的化感作用ꎬ土壤浸提液更接近植物实际环境[１０]ꎮ从植物－土壤－微生物三者关系来探讨作物连作障碍已经成为一个新的研究思路和重要发展趋势ꎮ因此ꎬ本研究分析了西洋参水提液和西洋参土壤浸提液对西洋参幼苗㊁根际土壤理化性质以及根际土壤真菌群落的影响ꎬ以期为缓解西洋参连作障碍提供有效策略ꎮ１㊀材料与方法１.１㊀采样与材料处理２０１９年１１月５日于陕西省留坝县火烧店镇墩墩石村西洋参种植基地(３３ʎ５７ᶄＮꎬ１０６ʎ８６ᶄＥ)进行采样ꎬ海拔１１００ｍꎮ在连续种植西洋参４年的地块采用 五点采样法 采集土壤(土壤深度１８~２０ｃｍ)和４年生健康西洋参ꎬ置于冰盒中用于土壤浸提液和西洋参根水提液的制备ꎮ清洗后的西洋参放入４ħ冰箱保存ꎬ土壤样品过２ｍｍ筛后置于阴凉处自然风干ꎮ西洋参种子购自留坝县西洋参研究所ꎮ营养土购自申之北有机土店ꎬ为长白山营养有机土ꎬ有机质ȡ３０％ꎬｐＨ值为４.８~６.５ꎬ执行标准为Ｑ/ＳＺＢ００１ ２０１８ꎮ１.２㊀西洋参根水提液及土壤浸提液制备称取４年生西洋参５０.０ｇꎬ打碎后加０.２Ｌ蒸馏水ꎬ混匀ꎬ超声提取１ｈ后浸泡过夜ꎬ用４层纱布过滤２次ꎬ所得滤液在７０００ｒ/ｍｉｎ下离心１０ｍｉｎꎬ取上清液将其稀释至０.１０ｇ/ｍＬꎬ４ħ低温贮５８㊀第２期㊀㊀㊀㊀㊀舒瑜ꎬ等:两种处理对西洋参根际土壤理化性质及真菌群落的影响藏待用ꎮ称取５００ｇ已过筛且风干的土壤ꎬ加入１Ｌ蒸馏水ꎬ混匀后超声提取１ｈꎬ浸泡过夜ꎬ用滤纸过滤得０.５０ｇ/ｍＬ土壤浸提液ꎬ４ħ低温贮藏待用ꎮ西洋参根水提液及其土壤浸提液在使用前１２１ħ灭菌２０ｍｉｎꎬ以排除病原菌影响ꎮ１.３㊀西洋参根水提液及其土壤浸提液对西洋参幼苗的处理选取露白２ｍｍ且状态健康的西洋参种子ꎬ播种到无菌营养土中ꎬ每盆(３１.５ｃｍˑ２４.５ｃｍˑ９.５ｃｍ)４０粒ꎮ分别使用蒸馏水(ＣＫ)㊁土壤浸提液(ＳＴ)和西洋参根水提液(ＧＴ)浇灌西洋参幼苗ꎬ一周浇液３次ꎬ每次３００ｍＬꎬ每个处理４个重复ꎬ在昼/夜温度为２４ħ/２１ħ㊁光照/黑暗为１２ｈ/１２ｈ的培养间培养西洋参幼苗ꎮ９０ｄ后收集待测土壤ꎬ过１ｍｍ筛ꎬ一份放置阴凉处风干ꎬ用于理化性质及酶活性测定ꎻ一份保存于－８０ħ冰箱ꎬ用于土壤真菌检测ꎮ１.４㊀土壤理化性质及酶活性测定配制土ʒ水为１ʒ２.５(ｗ/ｖ)的溶液ꎬ充分振荡３ｍｉｎ后静置３０ｍｉｎꎬ用ｐＨ计测定ｐＨ值ꎻ采用高智能土壤养分检测仪ＹＴ－ＴＲ０１(山东云唐智能科技有限公司)测定土壤碱解氮(ＡＮ)㊁铵态氮(ＡＭＮ)㊁速效磷(ＡＰ)㊁速效钾(ＡＫ)㊁有机质(ＯＭ)含量ꎻ参照关松萌[１１]的方法ꎬ采用紫外分光光度法测定过氧化氢酶(ＣＡＴ)活性ꎬ采用３ꎬ５－二硝基水杨酸比色法测定土壤转化酶(ＩＮＶ)活性ꎬ采用比色法测定土壤脲酶(ＵＲＥ)活性ꎬ采用磷酸苯二钠比色法测定土壤磷酸酶(ＰＨＯ)活性ꎮ１.５㊀土壤基因组ＤＮＡ提取和ＰＣＲ扩增按照ＴＩＡＮａｍｐＳｏｉｌＤＮＡＫｉｔ(ＴＩＡＮＧＥＮＢＩＯ￣ＴＥＣＨ)试剂盒说明书提取土壤微生物基因组ＤＮＡꎬ利用琼脂糖凝胶电泳检测ＤＮＡ纯度和浓度ꎮ将基因组ＤＮＡ用超纯水稀释ꎬ用含有Ｂａｒ￣ｃｏｄｅ的特异引物Ｆ(５ᶄ￣ＣＴＴＧＧＴＣＡＴＴＴＡＧＡＧ￣ＧＡＡＧＴＡＡ￣３ᶄ)和Ｒ(５ᶄ￣ＧＣＴＧＣＧＴＴＣＴＴＣＡＴＣＧＡＴ￣ＧＣ￣３ᶄ)扩增ＩＴＳ１－１Ｆ区域ꎮＰＣＲ反应体系:ＰＨｕ￣ｓｉｏｎ®Ｈｉｇｈ－ＦｉｄｅｌｉｔｙＰＣＲＭａｓｔｅｒＭｉｘ１５mＬꎬ模板ＤＮＡ２mＬꎬＦ㊁Ｒ引物(１０mｍｏｌ/Ｌ)各１mＬꎬｄｄＨ２Ｏ补足至３０mＬꎮ反应程序:９８ħ预变性１ｍｉｎꎻ９８ħ变性１０ｓꎬ５０ħ退火３０ｓꎬ７２ħ延伸３０ｓꎬ３０个循环ꎻ最后７２ħ延伸５ｍｉｎꎮ用２％琼脂糖凝胶电泳检测ＰＣＲ产物ꎬ使用Ｑｉａｇｅｎ公司的胶回收试剂盒对目的条带进行回收ꎮ１.６㊀文库构建和上机测序使用ＴｒｕＳｅｑ®ＤＮＡＰＣＲ－ＦｒｅｅＳａｍｐｌｅＰｒｅｐａ￣ｒａｔｉｏｎＫｉｔ建库试剂盒构建文库ꎬ随后经过Ｑｕｂｉｔ和Ｑ－ＰＣＲ定量ꎬ检验合格后ꎬ使用ＮｏｖａＳｅｑ６０００进行上机测序ꎮ委托北京诺禾致源科技股份有限公司完成ꎮ１.７㊀生物信息学分析采用余妙等[２]的方法基于ＩｌｌｕｍｉｎａＮｏｖａＳｅｑ测序平台对该文库进行双末端测序(Ｐａｉｒｅｄ＿Ｅｎｄ)及后续分析ꎮ１.８㊀数据处理利用ＭｉｃｒｏｓｏｆｔＥｘｃｅｌ２０１０软件处理数据ꎬ使用ＳＰＳＳ２２.０进行试验数据分析ꎮ２㊀结果与分析２.１㊀两种处理对西洋参幼苗及土壤参数影响ＣＫ㊁ＧＴ㊁ＳＴ组西洋参幼苗在播种１４ｄ后达到最大出苗率ꎬ分别为９８.３３％㊁８８.３３％㊁８２.５０％ꎬ继续处理后ꎬＧＴ组和ＳＴ组西洋参幼苗逐渐死亡ꎮ第４５天时ꎬＧＴ组和ＳＴ组西洋参幼苗死苗率达到７４.５８％和６４.５９％(图１)ꎬ分别是ＣＫ组的４.３８倍和３.７７倍ꎬ表明西洋参水提液及其土壤浸提液明显抑制西洋参幼苗的生长ꎮ由表１可知ꎬＧＴ和ＳＴ处理组的ｐＨ值和铵态氮含量较ＣＫ组均显著下降ꎬ其中ＧＴ组和ＳＴ组ｐＨ值分别下降０.４５和０.４４ꎬ表明两种处理下的土壤有酸化趋势ꎻＧＴ组和ＳＴ组中碱解氮含量显著升高ꎬ分别为ＣＫ组的４.００倍和１.７５倍ꎻＧＴ组中速效钾含量显著升高ꎬ为ＣＫ组的１.４０倍ꎻＳＴ组中速效磷含量显著下降ꎬ表明两种处理对西洋参幼苗根际土壤理化性质有显著影响ꎮ与ＳＴ组相比ꎬＧＴ组铵态氮含量显著降低２１.９６％ꎻ速效磷㊁速效钾㊁碱解氮含量显著升高ꎬ分别升高４０.７５％㊁３１.１３％和１２９.０９％ꎮＧＴ组中转化酶和脲酶活性显著高于ＣＫ组ꎬ分别为ＣＫ组的１２.０９倍和１.４３倍ꎬ过氧化氢酶和磷酸酶活性无明显变化ꎬ表明ＧＴ组土壤有利于西洋参对营养物质和氮的吸收ꎻ而ＳＴ组与ＣＫ组相比酶活性变化较小ꎮ与ＳＴ组相比ꎬＧＴ组转化酶和６８山东农业科学㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀第５５卷㊀脲酶活性显著升高ꎬ分别为ＳＴ组的６.１１倍和１.６４倍ꎬ过氧化氢酶和磷酸酶活性无显著变化ꎮ图为播种第４５天西洋参幼苗生长情况ꎻＡ:蒸馏水处理组(ＣＫ)Ｂ:西洋参根水提液处理组(ＧＴ)Ｃ:连作土壤浸提液处理组(ＳＴ)ꎮ图１㊀不同处理对西洋参幼苗生长的影响㊀㊀表１㊀不同处理对西洋参幼苗根际土壤参数及酶活性的影响项目ＣＫＧＴＳＴｐＨ值７.１８ʃ０.０９ａ６.７３ʃ０.０５ｂ６.７４ʃ０.０８ｂ有机质(ｇ/ｋｇ)６４.９８ʃ３.７１ａ７０.３８ʃ４.２６ａ６５.０３ʃ９.３９ａ铵态氮(ｍｇ/ｋｇ)７１.４３ʃ８.０４ａ４３.４５ʃ６.１１ｃ５５.６８ʃ５.００ｂ速效磷(ｍｇ/ｋｇ)５６.５４ʃ４.３１ａ５２.６０ʃ１０.０９ａ３７.３７ʃ５.００ｂ速效钾(ｍｇ/ｋｇ)２６４.０２ʃ３４.６３ｂ３６８.８９ʃ３４.０３ａ２８１.３１ʃ１６.８６ｂ碱解氮(ｇ/ｋｇ)１.２６ʃ０.２３ｃ５.０４ʃ０.４８ａ２.２０ʃ０.７０ｂ过氧化氢酶[ｍｇ/(ｋｇ ｄ)]１.８６ʃ０.９１ａ１.８２ʃ０.６９ａ１.３１ʃ０.５７ａ脲酶[ｍｇ/(ｋｇ ｄ)]４.４２ʃ０.７７ｂ６.３３ʃ０.２５ａ３.８５ʃ０.７２ｂ转化酶[ｍｇ/(ｋｇ ｄ)]０.４６ʃ０.０９ｂ５.５６ʃ０.８５ａ０.９１ʃ０.０９ｂ磷酸酶[ｍｇ/(ｋｇ ｄ)]０.２５ʃ０.０５ｂ０.３５ʃ０.０２ａｂ０.４１ʃ０.１０ａ㊀㊀注:同行不同字母表示不同处理在Ｐ<０.０５水平差异显著ꎬ表中数值为平均值ʃ标准差(ｎ＝４)ꎮ下同ꎮ２.２㊀真菌菌群测序深度及ＰＣＡ分析由图２Ａ可知ꎬ１２个样品的稀释曲线均趋于平坦ꎬ表明测序量趋于饱和ꎬ更多的测序对产生新的ＯＴＵ数目影响较小ꎮ图２Ｂ为基于ＯＴＵ水平的ＰＣＡ图ꎬＰＣ１和ＰＣ２分别代表１８.１１％和１４.９７％的真菌群落变化ꎬ３组样品能够被明显分开ꎬ且每组样品都有组内聚集现象ꎬ表明不同处理的样品真菌群落结构差别明显ꎬ同组样品真菌群落构成差异较小ꎮＳＴ组与ＣＫ组和ＧＴ组的距离均较近ꎬ但ＣＫ组与ＧＴ组距离较远ꎬ说明ＳＴ组与ＣＫ组和ＧＴ组分别具有较高的真菌群落相似性ꎮ图２㊀样本稀释曲线(Ａ)和ＰＣＡ结果(Ｂ)２.３㊀真菌菌群多样性分析通过对高通量测序结果除杂等质控步骤后ꎬＣＫ组㊁ＧＴ组㊁ＳＴ组分别得到拼接序列８５３１８㊁８６９５７㊁７５１１２条ꎬ去除嵌合体序列得到有效序列分别为６７７９６㊁６４７３３㊁５９５３６条ꎬ有效率分别为７９.４６％㊁７４.４４％及７９.２６％ꎮ根据９７％序列相似７８㊀第２期㊀㊀㊀㊀㊀舒瑜ꎬ等:两种处理对西洋参根际土壤理化性质及真菌群落的影响度进行水平聚类ꎬＣＫ组㊁ＧＴ组㊁ＳＴ组中各包含ＯＴＵ数目为３９３㊁３２１㊁３１９个ꎬ３组样品中共有ＯＴＵ数为２１２个ꎬＣＫ组㊁ＧＴ组㊁ＳＴ组特有的ＯＴＵ分别为９３㊁４７㊁６１个ꎬＧＴ组和ＳＴ组共有ＯＴＵ数目最少ꎬ为２２３个ꎬ表明ＧＴ组与ＳＴ组物种丰度差异较大ꎮＣｈａｏ１指数和ＡＣＥ指数用来表示土壤样品中真菌群落物种总数ꎬ指数越大代表物种种类越多ꎮＣＫ组Ｃｈａｏ１指数和ＡＣＥ指数最高ꎬ为２６４.４８和２７３.９３ꎬ分别为ＧＴ组和ＳＴ组的１.１２㊁１.４０倍和１.１６㊁１.４１倍(表２)ꎮＳｈａｎｎｏｎ指数和Ｓｉｍｐｓｏｎ指数综合反映土壤真菌群落的丰富度和均匀度ꎬ其指数越大代表均匀度和多样性越高ꎮＣＫ组Ｓｈａｎｎｏｎ指数和Ｓｉｍｐｓｏｎ指数最低ꎬ为３.６８和０.８６ꎬ３组真菌群落均匀度为ＣＫ组<ＳＴ组<ＧＴ组ꎮ以上数据表明ꎬＣＫ组物种种类最多ꎬ真菌群落均匀度最低ꎬＳＴ组物种种类最少ꎬＧＴ组真菌群落均匀度最高ꎮ㊀㊀表２㊀不同处理对西洋参栽培土壤真菌多样性指数的影响处理Ｓｈａｎｎｏｎ指数Ｓｉｍｐｓｏｎ指数Ｃｈａｏ１指数ＡＣＥ指数ＣＫ３.６８ʃ０.０４ｂ０.８６ʃ０.００ｂ２６４.４８ʃ１１.７４ａ２７３.９３ʃ１０.４３ａＧＴ４.２１ʃ０.１７ａ０.９０ʃ０.０２ａ２３５.１６ʃ１３.４０ａ２３７.００ʃ９.５６ｂＳＴ３.８０ʃ０.３１ｂ０.８８ʃ０.０２ａｂ１８９.０２ʃ３７.０６ｂ１９４.７２ʃ３７.２６ｃ２.４㊀真菌组成及差异菌群分析使用相对丰度柱形累加图比较３组样品在门和属水平的物种组成ꎮ图３Ａ为３组样品在门水平最大丰度排名前１０的物种ꎬ子囊菌门(Ａｓｃｏｍｙ￣ｃｏｔａ)为３组样品中的优势菌群ꎬ占真菌总数的６３.７７％~８６.５３％ꎬ其次为被孢霉门(Ｍｏｒｔｉｅｒｅｌｌｏｍｙ￣ｃｏｔａꎬ０.７４％~２１.３２％)㊁壶菌门(Ｃｈｙｔｒｉｄｉｏｍｙｃｏｔａꎬ０.０６％~５.８１％)㊁隐真菌门(Ｒｏｚｅｌｌｏｍｙｃｏｔａꎬ０.０４％~４.８０％)㊁担子菌门(Ｂａｓｉｄｉｏｍｙｃｏｔａꎬ０.０７％~３.５７％)和球囊菌门(Ｇｌｏｍｅｒｏｍｙｃｏｔａꎬ０.０２％~１.１３％)ꎬ其中被孢霉门和担子菌门在ＧＴ组中最高ꎬ分别占１５.０１％和２.３０％ꎻ隐真菌门在ＳＴ组中最高ꎬ占２.１２％ꎻＣＫ组中壶菌门㊁担子菌门㊁隐真菌门和球囊菌门丰度最低ꎬ均小于０.０２％ꎮ梳霉门(Ｋｉｃｋｘ￣ｅｌｌｏｍｙｃｏｔａ)为ＳＴ组中特有菌门ꎬ但丰度最高仅为０.０６％ꎬ捕虫霉门(Ｚｏｏｐａｇｏｍｙｃｏｔａ)仅在ＣＫ组中出现ꎬ丰度不到０.０１％ꎮ表明３组样品在门水平具有显著的物种丰度差异ꎮ在属水平上３组样品总共得到１７３个真菌类群ꎬ图３Ｂ为丰度前１０的物种ꎬ３组中优势菌属为镰刀菌属(Ｆｕｓａｒｉｕｍꎬ２３.９９％~２９.２０％)㊁Ｇｉｌ￣ｍａｎｉｅｌｌａ属(８.０６％~３７.４３％)㊁短梗蠕孢属(Ｔｒｉ￣ｃｈｏｃｌａｄｉｕｍꎬ４.７５％~８.５７％)㊁被孢霉属(Ｍｏｒｔｉｅｒｅｌ￣ｌａꎬ１.７４％~８.７０％)和毛壳菌属(Ｃｈａｅｔｏｍｉｕｍꎬ２.６５％~４.７７％)ꎬ其中ＣＫ组和ＳＴ组中Ｇｉｌｍａｎｉｅｌ￣ｌａ属和毛壳菌属丰度明显高于ＧＴ组ꎬ分别升高３６４.１４％和３５６.６７％ꎬ而镰刀菌属和被孢霉属明显低于ＧＴ组ꎬ分别降低２１.９０％㊁３５.８２％和５６.８６％㊁８０.００％ꎻＳＴ组短梗蠕孢属丰度显著高于ＣＫ组和ＧＴ组ꎬ分别提高８０.５２％和２８.７５％ꎻ未鉴别属(３.４１％)和被孢霉目中未鉴别属(２.９０％)是ＧＴ组优势属ꎬ且明显高于ＣＫ组和ＳＴ组ꎻＣｌａｄｏｒｒｈｉ￣ｎｕｍ属(２.６７％)和隐真菌门中未鉴别属(２.１１％)是ＳＴ组优势属ꎬ其丰度显著高于ＣＫ组和ＧＴ组ꎮ表明在属水平３组样品物种丰度具有显著差异ꎮ图３㊀不同处理样品主要土壤真菌群落在门水平(Ａ)和属水平(Ｂ)上组成㊀㊀为了进一步探究３组真菌群落在门和属水平的结构关系ꎬ寻找组间的差异物种ꎬ利用ＭｅｔａＳｔａｔ方法计算组间的物种丰度ꎬ发现在门水平上有４个差异物种(图４Ａ)ꎮＣＫ组和ＳＴ组子囊菌门丰度显著高于ＧＴ组ꎻ担子菌门和被孢霉门丰度ＧＴ组显著或极显著高于ＣＫ组和ＳＴ组ꎻ壶菌门丰度ＳＴ组显著高于ＧＴ组(Ｐ<０.０５)ꎬ极显著高于ＣＫ组(Ｐ<０.０１)ꎮ由图４Ｂ可知ꎬ属水平上有３个差异物种ꎮＣＫ组的Ｇｉｌｍａｎｉｅｌｌａ属丰度极显著高于ＧＴ组ꎻ被孢霉目未鉴别属和被孢霉科未鉴别属在８８山东农业科学㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀第５５卷㊀Ａ:门水平ꎻＢ:属水平ꎻ∗:Ｐ<０.０５ꎻ∗∗:Ｐ<０.０１ꎮ图４㊀组间显著差异物种丰度分布ＧＴ组中丰度最高ꎬ均显著高于ＳＴ组ꎬＣＫ组和ＳＴ组中均无显著差异ꎮ２.５㊀土壤理化性质与真菌的关联分析采用Ｓｐｅａｒｍａｎ相关系数(Ｓｐｅａｒｍａｎ ｓｒａｎｋｃｏｒｒｅｌａｔｉｏｎｃｏｅｆｆｉｃｉｅｎｔｓ)研究土壤理化性质与微生物物种之间的相互变化关系ꎮ如图５所示ꎬ土壤ｐＨ值与曲霉属(Ａｓｐｅｒｇｉｌｌｕｓꎬ０.７９)和周刺座霉属(Ｖｏｌｕｔｅｌｌａꎬ０.８２)呈极显著正相关ꎬ而与木霉属(Ｔｒｉｃｈｏｄｅｒｍａꎬ－０.８１)和Ｃｌａｄｏｒｒｈｉｎｕｍ属(－０.７４)呈极显著负相关(Ｐ<０.０１)ꎻ铵态氮可显著抑制Ｃｙｂｅｒｌｉｎｄｎｅｒａ属(－０.７４)和未鉴别属(－０.８８)真菌生长(Ｐ<０.０１)ꎻ速效磷含量与曲霉属(０.６８)㊁彼得壳属(０.５８)和被孢霉属(０.６４)呈显著正相关ꎬ与球囊菌门未鉴别属(－０.７６)㊁隐真菌门未鉴别属(－０.６４)和Ｃｌａｄｏｒｒｈｉｎｕｍ属(－０.７７)呈显著或极显著负相关(Ｐ<０.０５)ꎻ速效钾能极显著促进担子菌门未鉴别属(０.７３)㊁被孢霉目未鉴别属(０.８０)㊁头梗霉属(０.８４)㊁未鉴别属(０.７８)真菌的生长ꎬ抑制Ｇｉｌｍａｎｉｅｌｌａ属(－０.８３)生长(Ｐ<０.０１)ꎻ碱解氮含量和土壤转化酶活性导致的真菌变化规律基本一致ꎬ极显著促进木霉属(０.７３)和未鉴别属(０.８３)真菌生长(Ｐ<０.０１)ꎻ土壤脲酶活性与被孢霉属呈极显著正相关(Ｐ<０.０１)ꎬ与锥盖伞属(－０.６０)呈显著负相关(Ｐ<０.０５)ꎻ土壤磷酸酶活性增加导致隐真菌门未鉴别属(０.８３)极显著增多(Ｐ<０.０１)ꎬ周刺座霉属(－０.７９)极显著减少(Ｐ<０.０１)ꎮ以上结果表明ꎬ土壤理化性质和酶活性与土壤真菌密切相关ꎮ图５㊀Ｓｐｅａｒｍａｎ相关性分析热图９８㊀第２期㊀㊀㊀㊀㊀舒瑜ꎬ等:两种处理对西洋参根际土壤理化性质及真菌群落的影响３㊀讨论与结论土壤理化性质是植物正常发育的关键ꎬ植物分泌的物质会影响土壤理化性质ꎮ本研究发现ꎬ与ＣＫ组相比ꎬＧＴ组显著降低了铵态氮含量ꎬ显著提高了速效钾和碱解氮含量ꎬＳＴ组中铵态氮和速效磷含量显著降低ꎬ而碱解氮含量显著提高ꎮ王兴飞等[１２]研究发现ꎬ使用凤丹(Ｐａｅｏｎｉａｏｓｔｉｌ)根际土壤浸提液浇灌玉米幼苗显著降低了根际土壤中全氮㊁全磷和有机碳含量ꎻ张冉[１０]用种植过西洋参１至４年的土壤水提液分别浇灌未种植过西洋参的土壤ꎬ发现４年生参龄土壤处理的新土中铵态氮和有机质含量显著提高ꎬ而速效磷含量显著降低ꎬ与本研究结果相似ꎮ土壤铵态氮㊁速效钾和速效磷能够被植物吸收利用ꎬ其含量下降不利于植物生长ꎬ碱解氮是衡量土壤氮素的重要指标ꎬ而两种处理下的碱解氮含量均升高ꎬ可能是由于两种水提液中的有机质高于蒸馏水ꎬ也可能是两种水提液中的某些物质影响微生物ꎬ进而提高了碱解氮含量ꎮ土壤酶活性与土壤物质的转化密切相关ꎬ植物浸提液对土壤酶活性具有显著影响[１３]ꎮ张冉[１０]使用种植西洋参４年的土壤水提液浇灌新土ꎬ发现新土中土壤转化酶活性升高ꎬ过氧化氢酶㊁碱性磷酸酶和脲酶活性降低ꎻ孙雪婷等[１４]发现三七连作能显著降低其栽培土壤中蔗糖酶㊁过氧化氢酶㊁磷酸酶和脲酶活性ꎮ在本研究中ꎬＳＴ处理组相比于ＣＫ组碱性磷酸酶活性显著升高ꎬ过氧化氢酶㊁转化酶和脲酶活性没有显著变化ꎻＧＴ组中转化酶和脲酶活性显著升高ꎬ过氧化氢酶和磷酸酶活性没有显著变化ꎮ张亚玉等[１５]测定不同连作时长的西洋参土壤酶活性发现ꎬ相比于未种植过西洋参的土壤ꎬ种植４年西洋参的土壤过氧化氢酶和脲酶活性显著升高ꎮ本研究中两种处理均改变了上述酶活性ꎬ可能是由于两种水提液中的代谢物质直接作用于土壤酶ꎬ也可能是水提液影响了土壤理化性质和微生物结构ꎬ间接影响酶活性ꎮ药用植物分泌代谢物质到土壤中通常会引起原本微生物种类和数量的改变ꎮ一定浓度的阿魏酸㊁香草酸和丁香酸等酚酸类化合物能促进西洋参立枯丝核菌和根腐菌生长[１６]ꎻ焦晓林等[１７]发现４~４０ｍｇ/ｍＬ皂苷提取液能显著抑制立枯丝核菌㊁尖孢镰刀菌㊁毁灭柱孢菌生长(Ｐ<０.０５)ꎮ本研究对不同处理下土壤微生物群落组成结构的变化进行分析发现ꎬ与ＣＫ组相比ꎬＳＴ和ＧＴ组处理后的西洋参幼苗根际土壤真菌群落多样性降低ꎬ组成结构发生明显变化ꎮ在门水平上ꎬ子囊菌门在３组中分布最广泛ꎮ与ＣＫ组相比ꎬＧＴ组处理显著降低了西洋参幼苗根际土壤中子囊菌门数量ꎬ而被孢霉门㊁壶菌门和担子菌门丰度显著上升(Ｐ<０.０５)ꎻＳＴ组处理的西洋参幼苗根际土壤中ꎬ壶菌门和担子菌门丰度明显升高(Ｐ<０.０５)ꎬ这与袁源等[８]研究发现灵芝随着连作年限的增加ꎬ子囊菌门显著减少ꎬ担子菌门显著增加的结果相似ꎮ由此可知ꎬ西洋参中存在某些代谢物质显著抑制了子囊菌门的生长ꎬ而西洋参和西洋参连作土壤中含有的某些物质有利于被孢霉门㊁壶菌门和担子菌门真菌的生长ꎮ以往研究认为ꎬ镰刀菌属真菌是导致西洋参患病的主要病原菌[１８]ꎬ通过高通量测序发现在属水平上ꎬ镰刀菌属在３组中广泛分布ꎬ其中ꎬＧＴ组丰度最高ꎬ是ＣＫ组丰度的１.２８倍ꎮ此外ꎬ与ＣＫ组和ＳＴ组相比ꎬＧＴ组中Ｇｉｌ￣ｍａｎｉｅｌｌａ属真菌显著降低(Ｐ<０.０５)ꎬ被孢霉科未鉴别属和被孢霉目未鉴别属真菌显著升高(Ｐ<０.０５)ꎬ与唐彬彬等[１９]发现被孢霉属真菌随着三七连作年限增加而减少的结果相反ꎬ这可能与西洋参中的甾类化合物有关ꎮ以上结果表明ꎬ西洋参在种植过程中ꎬ分泌的代谢物质影响了土壤微生物群落构成ꎬ进而影响西洋参生长发育ꎮ土壤微生物作为根际微生态系统的主要构成ꎬ不仅与植物类型有关ꎬ与土壤理化性质同样紧密联系ꎮ有学者研究发现ꎬＳｐｈｉｎｇｏｂａｃｔｅｒｉｕｍ的丰度与ｐＨ值(Ｒ２＝０.８５６ꎬＰ<０.０５)和速效钾含量显著相关(Ｒ２＝－０.６５ꎬＰ<０.０５)[２０]ꎻＨｅｌｏｔｉａｌｅｓ(Ｒ２＝０.５３ꎬＰ<０.０１)㊁Ｈｙｐｏｃｒｅａｌｅｓ(Ｒ２＝０.６３ꎬＰ<０.０１)的丰度与土壤ｐＨ值显著相关[２１]ꎻＳｏｒｄａｒｉｏｍｙｃｅｔｅ的丰度与有效磷含量相关[２２]ꎮ本研究结果表明ꎬ西洋参幼苗根际土壤真菌群落结构受西洋参水提液及其连作土壤浸提液影响ꎬ其变化与土壤理化性质密切相关ꎮ曲霉属㊁周刺座霉属和Ｃｌａｄｏｒｒｈｉ￣ｎｕｍ属等真菌与ｐＨ值显著相关ꎻ土壤养分与Ｃｙ￣ｂｅｒｌｉｎｄｎｅｒａ属㊁Ｇｉｌｍａｎｉｅｌｌａ属和赤霉菌属等真菌显著相关ꎻ土壤酶活性与木霉属和被孢霉属等真菌０９山东农业科学㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀第５５卷㊀显著相关ꎮ该结果表明ꎬ土壤微生物群落变化与土壤理化性质的改变息息相关ꎬ优化土壤理化性质可缓解西洋参的连作障碍ꎮ综上所述ꎬ西洋参水提液及其连作土壤浸提液能够抑制西洋参的生长ꎬ并改变西洋参幼苗根际土壤的理化性质和真菌群落多样性ꎮ研究结果为西洋参连作障碍发生和机理的认识奠定了基础ꎮ参㊀考㊀文㊀献:[１]㊀舒秀丽.不同土壤处理对西洋参连作障碍的影响[Ｄ].泰安:山东农业大学ꎬ２０１１.[２]㊀余妙ꎬ蒋景龙ꎬ李丽ꎬ等.西洋参水提物对８种作物的化感效应[Ｊ].分子植物育种ꎬ２０１８ꎬ１６(２２):７５０３－７５１３. [３]㊀ＪｉａｎｇＪＬꎬＹｕＭꎬＨｏｕＲＰꎬｅｔａｌ.Ｃｈａｎｇｅｓｉｎｔｈｅｓｏｉｌｍｉｃｒｏｂｉ￣ａｌｃｏｍｍｕｎｉｔｙａｒｅａｓｓｏｃｉａｔｅｄｗｉｔｈｔｈｅｏｃｃｕｒｒｅｎｃｅｏｆＰａｎａｘｑｕｉｎ￣ｑｕｅｆｏｌｉｕｓＬ.ｒｏｏｔｒｏｔｄｉｓｅａｓｅｓ[Ｊ].Ｐｌａｎｔ＆Ｓｏｉｌꎬ２０１９ꎬ４３８(１/２):１４３－１５６.[４]㊀刘诗蓉ꎬ王红兰ꎬ杨萍ꎬ等.连作对半夏生长及次生代谢产物的影响[Ｊ].中药材ꎬ２０２２(１):１－６.[５]㊀ＬａｋｓｈｍａｎａｎＶꎬＳｅｌｖａｒａｊＧꎬＢａｉｓＨＰ.Ｆｕｎｃｔｉｏｎａｌｓｏｉｌｍｉｃｒｏｂｉ￣ｏｍｅ:ｂｅｌｏｗｇｒｏｕｎｄｓｏｌｕｔｉｏｎｓｔｏａｎａｂｏｖｅｇｒｏｕｎｄｐｒｏｂｌｅｍ[Ｊ].ＰｌａｎｔＰｈｙｓｉｏｌｏｇｙꎬ２０１４ꎬ１６６(２):６８９－７００. [６]㊀ＭｉａｏＣＰꎬＭｉＱＬꎬＱｉａｏＸＧꎬｅｔａｌ.ＲｈｉｚｏｓｐｈｅｒｉｃｆｕｎｇｉｏｆＰａ￣ｎａｘｎｏｔｏｇｉｎｓｅｎｇ:ｄｉｖｅｒｓｉｔｙａｎｄａｎｔａｇｏｎｉｓｍｔｏｈｏｓｔｐｈｙｔｏｐａｔｈｏ￣ｇｅｎｓ[Ｊ].ＪｏｕｒｎａｌｏｆＧｉｎｓｅｎｇＲｅｓｅａｒｃｈꎬ２０１６ꎬ４０(２):１２７－１３４.[７]㊀ＡｒａｖｉｎｄｒａｊａＣꎬＶｉｓｚｗａｐｒｉｙａＤꎬＫａｒｕｔｈａＰａｎｄｉａｎＳ.Ｕｌｔｒａ￣ｄｅｅｐ１６ＳｒＲＮＡｓｅｑｕｅｎｃｉｎｇａｎａｌｙｓｉｓｏｆｇｅｏｇｒａｐｈｉｃａｌｌｙｓｉｍｉｌａｒｂｕｔｄｉ￣ｖｅｒｓｅｕｎｅｘｐｌｏｒｅｄｍａｒｉｎｅｓａｍｐｌｅｓｒｅｖｅａｌｖａｒｉｅｄｂａｃｔｅｒｉａｌｃｏｍ￣ｍｕｎｉｔｙｃｏｍｐｏｓｉｔｉｏｎ[Ｊ].ＰＬｏＳＯＮＥꎬ２０１３ꎬ８(１０):ｅ７６７２４. [８]㊀袁源ꎬ黄海辰ꎬ叶丽云ꎬ等.灵芝连作土壤真菌群落分析[Ｊ].菌物学报ꎬ２０１９ꎬ３８(１２):２１１２－２１２１. [９]㊀董艳鑫ꎬ蒋景龙ꎬ李丽.西洋参根及其土壤浸提液对其幼苗生长影响研究[Ｊ].中药材ꎬ２０２１ꎬ４４(３):５３３－５３７.[１０]张冉.西洋参土壤水提液对土壤微生物群落㊁养分和酶活性的影响[Ｄ].西安:陕西师范大学ꎬ２０１７.[１１]关松萌.土壤酶及其研究法[Ｍ].北京:农业出版杜ꎬ１９８６. [１２]王兴飞ꎬ王振东ꎬ王友保ꎬ等.凤丹浸提液对玉米幼苗生长和根际土壤性质的影响[Ｊ].西北农林科技大学学报(自然科学版)ꎬ２０１５ꎬ４３(１０):１９－２６.[１３]ＯｋｕｒＮꎬＴｕｎａＡＬꎬＯｋｕｒＢꎬｅｔａｌ.Ｎｏｎ￣ｔａｒｇｅｔｅｆｆｅｃｔｏｆｏｒｇａｎｉｃｉｎｓｅｃｔｉｃｉｄｅｓ:ｅｆｆｅｃｔｏｆｔｗｏｐｌａｎｔｅｘｔｒａｃｔｓｏｎｓｏｉｌｍｉｃｒｏｂｉａｌｂｉｏ￣ｍａｓｓａｎｄｅｎｚｙｍａｔｉｃａｃｔｉｖｉｔｉｅｓｉｎｓｏｉｌ[Ｊ].ＥｎｖｉｒｏｎｍｅｎｔａｌＭｏｎｉ￣ｔｏｒｉｎｇ＆Ａｓｓｅｓｓｍｅｎｔꎬ２０１０ꎬ１６５(１/２/３/４):３８９－３９７. [１４]孙雪婷ꎬ龙光强ꎬ张广辉ꎬ等.基于三七连作障碍的土壤理化性状及酶活性研究[Ｊ].生态环境学报ꎬ２０１５ꎬ２４(３):４０９－４１７.[１５]张亚玉ꎬ宋晓霞ꎬ孙海ꎬ等.栽培人参㊁西洋参不同年限土壤酸碱度和酶活性的变化[Ｊ].特产研究ꎬ２００８ꎬ３０(４):３４－３６.[１６]杨家学ꎬ高微微.酚酸类化感物质对两种西洋参病原真菌的作用[Ｊ].中国农学通报ꎬ２００９ꎬ２５(９):２０７－２１１. [１７]焦晓林ꎬ杜静ꎬ毕晓宝ꎬ等.西洋参中酚酸及皂苷成分对病原菌的作用[Ｊ].中国农学通报ꎬ２０１５ꎬ３１(１７):１０５－１１０. [１８]毕武ꎬ陈娟ꎬ焦晓林ꎬ等.北京地区西洋参根腐病病原鉴定及其致病性[Ｊ].植物保护ꎬ２０１１ꎬ３７(５):１３５－１３８. [１９]唐彬彬ꎬ董姚君ꎬ贺密密ꎬ等.云南文山健康三七种植年限对根际微生物群落的影响[Ｊ].微生物学通报ꎬ２０２０ꎬ４７(９):２８５７－２８６６.[２０]ＺｈａｏＪꎬＺｈｏｕＸꎬＪｉａｎｇＡＱꎬｅｔａｌ.Ｄｉｓｔｉｎｃｔｉｍｐａｃｔｓｏｆｒｅｄｕｃ￣ｔｉｖｅｓｏｉｌｄｉｓｉｎｆｅｓｔａｔｉｏｎａｎｄｃｈｅｍｉｃａｌｓｏｉｌｄｉｓｉｎｆｅｓｔａｔｉｏｎｏｎｓｏｉｌｆｕｎｇａｌｃｏｍｍｕｎｉｔｉｅｓａｎｄｍｅｍｂｅｒｓｈｉｐｓ[Ｊ].ＡｐｐｌｉｅｄＭｉｃｒｏｂｉｏｌｏ￣ｇｙａｎｄＢｉｏｔｅｃｈｎｏｌｏｇｙꎬ２０１８ꎬ１０２(１７):７６２３－７６３４. [２１]ＲｏｕｓｋＪꎬＢååｔｈＥꎬＢｒｏｏｋｅｓＰＣꎬｅｔａｌ.Ｓｏｉｌｂａｃｔｅｒｉａｌａｎｄｆｕｎ￣ｇａｌｃｏｍｍｕｎｉｔｉｅｓａｃｒｏｓｓａｐＨｇｒａｄｉｅｎｔｉｎａｎａｒａｂｌｅｓｏｉｌ[Ｊ].ＩＳＭＥＪｏｕｒｎａｌꎬ２０１０ꎬ４(１０):１３４０－１３５１.[２２]ＬａｕｂｅｒＣＬꎬＳｔｒｉｃｋｌａｎｄＭＳꎬＢｒａｄｆｏｒｄＭＡꎬｅｔａｌ.Ｔｈｅｉｎｆｌｕ￣ｅｎｃｅｏｆｓｏｉｌｐｒｏｐｅｒｔｉｅｓｏｎｔｈｅｓｔｒｕｃｔｕｒｅｏｆｂａｃｔｅｒｉａｌａｎｄｆｕｎｇａｌｃｏｍｍｕｎｉｔｉｅｓａｃｒｏｓｓｌａｎｄ￣ｕｓｅｔｙｐｅｓ[Ｊ].ＳｏｉｌＢｉｏｌｏｇｙａｎｄＢｉｏ￣ｃｈｅｍｉｓｔｒｙꎬ２００８ꎬ４０(９):２４０７－２４１５.１９㊀第２期㊀㊀㊀㊀㊀舒瑜ꎬ等:两种处理对西洋参根际土壤理化性质及真菌群落的影响。

干旱条件下棉花根际真菌多样性分析

作物学报 ACTA AGRONOMICA SINICA 2021, 47(9): 1806 1815 / ISSN 0496-3490; CN 11-1809/S; CODEN TSHPA9 E-mail: zwxb301@本研究由国家重点研发计划项目“大田经济作物优质丰产的生理基础与调控”(2018YFD1000907)资助。

This study was supported by the National Key Research and Development Program of China “Physiological Basis and Agronomic Manage-ment for High-quality and High-yield of Field Cash Crops” (2018YFD1000907).*通信作者(Corresponding author): 杨细燕, E-mail: yxy@第一作者联系方式: E-mail: ddyue@Received (收稿日期): 2020-07-20; Accepted (接受日期): 2021-01-21; Published online (网络出版日期): 2021-02-25. URL: https:///kcms/detail/11.1809.S.20210225.1448.011.htmlDOI: 10.3724/SP.J.1006.2021.04162干旱条件下棉花根际真菌多样性分析岳丹丹 韩 贝 Abid Ullah 张献龙 杨细燕*华中农业大学作物遗传改良国家重点实验室, 湖北武汉 430070摘 要: 植物根际微生物群落对植物生长和适逆性至关重要, 本研究对干旱条件下棉花根际真菌群落进行分析, 旨在探明干旱胁迫对棉花根际真菌多样性和群落结构的影响, 为利用有益微生物提高棉花水分利用率提供理论依据。

以陆地棉Jin 668 (Gossypium hirsutum cv. Jin668)为试验材料, 采用盆栽控水方式, 对处于开花期的棉花根际土壤(SDP)和未种植棉花土壤(SOPD)进行干旱处理, 正常浇水的棉花根际土壤(SPN)和无棉花土壤(SNPN)为对照。

作物土传真菌病害发生的根际微生物机制研究进展

作物土传真菌病害发生的根际微生物机制研究进展杨珍;戴传超;王兴祥;李孝刚【摘要】土传病害是制约我国农业生产可持续发展的重要瓶颈.根际是作物养分高效利用的窗口, 是植物-土壤-微生物相互作用的关键微域, 也是土传病害发生发展的主要场所.在宏基因组学快速发展的今天, 了解根际微生物与土传病害互作关系, 有利于从微生物种群、功能代谢和抑病物质等研究找出防控土传病害的有效方法.本文综述了根际微生物与土传真菌病害的发生机制关系, 探讨了土传病原真菌致害机理, 并提出目前研究的不足和未来研究的重点.目前, 我国农业生产中土传真菌病害发生严重, 很多是由不同病原菌复合侵染的结果, 其致害机理较为复杂.定向优化根际微生物群落结构提升植物根际微生态抗性, 是防控土传病害途径之一, 应加以重视.现有研究多偏向根际促生微生物, 而忽视了根际有害细菌与病害发生和作物生长的关系.今后的研究应系统评估土传真菌病害的发生及危害程度、归类土传真菌病原菌类型、深入研究土传真菌病害发生的根际微生态机理以及研发土传真菌病害综合防控技术.%Soil-borne diseases have become a major bottleneck restraining sustainable development of the agriculture in China. Rhizosphere is a window displaying how efficiently a crop uses soil nutrients, a key micro-domain of plant-soil-microbe interactions, as well as a major scene where soil-borne diseases develop. Today when metagenomics is developing so rapidly, any knowledge about interactions between rhizosphere microorganisms and soil-borne fungal diseases is conducive to exploration for effective ways to prevent and control soil-borne diseases from the aspects of microbial community, metabolic function, and disease suppressants. With reference to the databases ofScopus, Web of Science and China National Knowledge Infrastructure, a review is presented in this paper summarizing relationships between soilborne fungal diseases and rhizosphere microorganisms, discussing pathogenesis of soil-borne disease fungi, and pointing out shortages of the current researches and focal points for future researches. Currently, the incidence of soil-borne fungal diseases is very high in agricultural production of the country, and incidence of most soil-borne fungal diseases is the result of complex infections of a variety of pathogens. Oriented optimization of the structure of rhizospheric microbial communities is an effective way to enhance their antagonism to soil-borne fungal diseases for control of incidence of the diseases. So it is a noteworthy method. So far, quite a number of papers are found in the literature addressing relationships between rhizosphere probiotic microorganisms and health and growth of plants, but few are exploring impacts of harmful bacteria in the rhizosphere on incidence of soil-borne diseases and crop growth. Studies in future should be oriented to systematically assess the incidence and damage of soil-borne fungal diseases, classify soil-borne pathogens by type, explore in depth micro-ecological mechanism of rhizosphere in incidence of soil-borne diseases, and develop a comprehensive technological system for management of soil-borne diseases.【期刊名称】《土壤学报》【年(卷),期】2019(056)001【总页数】11页(P12-22)【关键词】土传真菌病害;根际微生物;微生物多样性;防控技术;作物抗性【作者】杨珍;戴传超;王兴祥;李孝刚【作者单位】南京师范大学生命科学学院,南京 210023;中国科学院南京土壤研究所,南京 210008;南京师范大学生命科学学院,南京 210023;中国科学院南京土壤研究所,南京 210008;中国科学院南京土壤研究所,南京 210008【正文语种】中文【中图分类】S182近年来我国农作物的土传病害日趋严重，对农作物产量和品质造成严重影响，已成为限制我国农业可持续发展的重要瓶颈。

呼和浩特市云杉土壤真菌种群分布

呼和浩特市云杉土壤真菌种群分布白丽梅;包晓英;姜海燕【摘要】[目的]明确云杉土壤真菌的种群结构.[方法]利用选择性培养基,研究了云杉土壤真菌的数量分布和种群组成.[结果]云杉土壤真菌数量随生长季月份的变化趋势是7月＞6月＞8月＞5月＞9月＞ 10月＞4月,垂直变化趋势是随着土壤深度的增加,真菌数量呈递减趋势;云杉土壤中共分离到产孢真菌332株,分属于24属,优势菌属为腐霉属、毛霉属、青霉属、汉斯霉属.[结论]云杉土壤真菌种群分布具有多样性.【期刊名称】《安徽农业科学》【年(卷),期】2014(000)018【总页数】2页(P5787-5788)【关键词】云杉;土壤真菌;种群结构【作者】白丽梅;包晓英;姜海燕【作者单位】内蒙古包头市石拐区林业局,内蒙古包头014030;内蒙古内蒙古通辽市科左中旗林业工作站,内蒙古通辽029000;内蒙古农业大学林学院,内蒙古呼和浩特010019【正文语种】中文【中图分类】S154.3土壤是微生物生活的良好场所。

微生物在土壤养分转化和腐殖质形成过程中有着重要的作用，并且积极参与生态系统的物质循环和能量流动，其生命活动直接影响生态系统的结构和功能［1-6］。

而土壤真菌是土壤微生物区系中的主要成分，在推动土壤物质转换、能量流动和生物地化循环中均起着重要的作用［5］。

土壤真菌作为检测土壤质量变化的敏感指标，其多样性在评价生态系统功能、维护生态平衡中发挥着重要作用［6-8］。

笔者研究了内蒙古农业大学东区云杉土壤真菌种群组成和数量分布，为该区的生物多样性研究及认识土壤发育与成因提供依据。

1 材料与方法1.1 样品采集在内蒙古农业大学东区，选择云杉种植地，设置研究样地，利用多点混合采样法采集0～10、10～20、20～30、30～40、40～50 cm的土壤，过2 mm 筛后带回实验室，4℃冷藏，保鲜，待用［9］。

1.2 土壤真菌的分离与鉴定土壤真菌的计数采用稀释平板法［10-12］，稀释倍数为 10-2～10-4，每个稀释浓度 3 次重复，选择长出菌落数10～200的培养皿计数。

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ScientiaHorticulturae150(2013)100–109ContentslistsavailableatSciVerseScienceDirectScientiaHorticulturae

journalhomepage:www.elsevier.com/locate/scihorti

Soilmicrobialcommunitiesassociatedwiththerhizosphereofcucumberunderdifferentsummercovercropsandresiduemanagement:A4-yearfieldexperiment

YongqiangTiana,b,XueyanZhangc,JingguoWangb,LihongGaoa,∗aBeijingKeyLaboratoryofGrowthandDevelopmentalRegulationforProtectedVegetableCrops,DepartmentofVegetableScience,ChinaAgriculturalUniversity,No.2Yuanmingyuan

Xilu,Beijing100193,ChinabCollegeofResourcesandEnvironmentalSciences,ChinaAgriculturalUniversity,No.2YuanmingyuanXilu,Beijing100193,China

cCollegeofAgriculture,NingxiaUniversity,489HelanshanXilu,Yinchuan750021,China

articleinfoArticlehistory:Received30April2012Receivedinrevisedform27October2012Accepted29October2012Keywords:SoilmicrobialcommunityEnzymesRhizosphereGreenhousecucumberabstractContinuouscroppinghasledtothepredominantdeclineofsoilproductivityandcropyieldsinChinesevegetableproductionsystems.Recently,theuseofsummercovercropstorestoredegradedsoildur-

ingvegetableproductionhasattractedattentioninChina.A4-yearfieldexperimentonagreenhousecucumberdouble-croppingsystemwasthereforeconductedtounderstandhowdifferentsummercovercropsaffectsoilmicrobialcommunitiesassociatedwiththecroprhizosphere.Thetreatmentsincludedsweetcornwithresidueremovalafterharvest(SR),sweetcornwithresidueincorporationafterharvest

(SI),commonbeanwithresidueremovalafterharvest(CR),commonbeanwithresidueincorporationafterharvest(CI),Garlandchrysanthemumandedibleamaranthassummercovercrops(GR),andbarefallowduringthesummerperiod(Control).Soilmicrobialcommunitieswereevaluatedwithacom-

binationofsole-carbon-sourceutilizationcapacities,thepopulationofmicroorganismsandenzymes.

Generally,sole-carbonutilizationcapabilitiesandenzymeactivitieswerehigherinthesummercovercrop-relatedsoilscomparedtocontrolsoilineachcroppingseason.Multivariateanalysisindicatedthatmicrobialcommunitiesdifferedamongthecroppingseasons,andsignificantlyseparatedsummercovercroptreatmentsfromthecontrol.TreatmentsSR,SIandGRwithrelativelyhighcucumberproductiv-

itygenerallyshowedrelativelyhighureaseactivityandrelativelylowFusariumoxysporumpopulation.Weconcludedthatsummercovercropsgenerallyhadagreatereffectonsoilmicrobialcommunitiesassociatedwithcroprhizospherecomparedtothetraditionalbarefallow.Soilmicroorganismsassoci-atedwithcroprhizosphereplayedanimportantroleduringthephytoremediationprocessesofsummer

covercrops.©2012ElsevierB.V.Allrightsreserved.

1.IntroductionAsthecountrywiththelargestpopulationintheworld,Chinatakesitsvegetablesupplyasaveryimportantmatter(Guoetal.,2010).Theartificialenvironmentofplasticgreenhouseisusuallysuitableforvegetablegrowthandcangeneratemuchmoreyieldandincomethanopen-fieldcultivationinChina(Gaoetal.,2010).Greenhousevegetablecroppinghasbecomemoreandmorepopu-larinChinaoverthelast30years,reachinganareaof4,667,000hain2010(Yu,2011).Asaneconomicallyimportantcrop,cucum-berisoneofthemajorgreenhousevegetablesinChina(Huangetal.,2009;Tianetal.,2011b).However,continuouscroppingunderplasticgreenhousehascausedsoilqualitydegradation(e.g.∗Correspondingauthor.Tel.:+861062732825;fax:+861062732825.E-mailaddress:gaolh@cau.edu.cn(L.Gao).soilacidification,secondarysalination,nutrientunbalance)result-inginareductionofplantproduction(Yaoetal.,2006).Hence,remediationofdegradedsoilsisoneofthemajorchallengesinenvironmentalscience.Low-cost,efficient,andenvironmentallyfriendlyremediationtechnologiestoimprovedegradedsoilsareurgentlyneededduringvegetableproduction.Recently,phytoremediation,theuseofsummercovercropstorestoredegradedsoil,hasattractedattentioninChina(Juetal.,2007;Wuetal.,2007;Guoetal.,2008).Apivotalsteptowardthephytoremediationofdegradedsoilsisthediscoveryofthesuit-ablecovercropsgrowingduringthesummerfallowperiod.Severalcrops,suchassweetcorn(ZeamaysL.),commonbean(Phaseo-lusvulgarisL.),Garlandchrysanthemum(ChrysanthemumsegetumL.)andedibleamaranth(AmaranthusmangostanusL.),havebeenselectedassummercovercropsingreenhousevegetableproduc-tionsystems.Apreviousstudyreportedthatsweet-cornplantinginsummerfallowperiodwasanefficienttooltoreducetherisk

0304-4238/$–seefrontmatter©2012ElsevierB.V.Allrightsreserved.http://dx.doi.org/10.1016/j.scienta.2012.10.025

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