Study On VA Mycorrhizal Fungal Influnce On Salt-Resistant Mechanisms Of Maize Plants And Microbiological Diversity In Farmland Soils

The composition community of AMF(Arbuscular Mycorrhizal Fungi)in rhizospheres of25 common plants(Allium fistulosum,Caragana korshinkii,Glycyrrhiza uralensis,Alhagisparsifolia,Medicago sativa,Oryza sativa,Zae mays,Agropyron cristatum,Leymus chinensis,Achnatherum splendens,Spartina anglica,Triticum aestivum,Phragmites australis,Elaegnusangustifolia,Nitraria tangutorum,Gossypium herbaceum,Helianthus annnus,Ailanthusaltissima,Saliconia europaea,Lycium chinense,Carex kobomugi,C.duriuscula,Salixgordejevii,Populus euphratica and Iris lactea)in saline alkaline soils of Gansu province,Ningxia Hui Autonomous Region and Inner Mongolia Autonomous Region was investigated.The relationship between AMF composition community and soil factors was analyzed as well.The influence of AMF(Glomus mosseae)on salt-resistant mechanisms of maize plants undersalt stress was studied in the greenhouse.Whilst,we analyzed the relationship between soiltype,soil properties,climate conditions and microbiological diversity in farmland soils ofSaskatchewan,Canada,and built two models to figure out the relationship among AMF,soilproperties and contents of N and P in wheat plants.The results are as follows:1.In total,twenty-eight AMF species belonging to 4 genera were identified fromrhizospheres of 25 common plants.There were 4 Acaulospora(A.lacunose,A.rugosa,A.scrobiculata and A.spinosa),2 Archaeospora(At.Gerdemannii and Ar.leptotichum),2Diversispora(D.etunicatum and D.versiforme),and 20 Glomus(G.aggregatum,G.albidum,G.australe,G.claroideum,G.clarum,G.constrictum,G.coronatum,G.diaphanum,G.fasciculatum,G.geosporum,G.intraradices,G.manihotis,G.mosseae,G.pansihalos,G.pustulatum,G.reticulatum,G.tenebrosum,G.trimurales,G.verruculosum and G.vesiculiferum).Among them,G.vesiculiferum and G.trimurales were new record species inChina.Glomus,Diversispora and Archaeospora were the dominant genera.G.constrictum,G.geosporum,G.intraradices,D.versiforme and Ar.Leptotichum were the dominant species.2.All twenty-five plant species,including Carex kobomugi and C.duriuscula of theCyperaceae,were colonized by AMF.The structural type of VA(Vesicular Arbuscular)mycorrhizae of C.kobomugi could not be identified;most other plant species(66.7%) belonged to the Arum-type,33.3% belonged to the Paris-type,the intermediate type was notfound.3.AMF spore density was negatively correlated with SO₄^2-concentration,but positivelywith the number of fungi and bacteria.AMF spore density was influenced directly by soil pHand concentrations of SO₄^2-,Olsen-P,Olsen-K and Olsen-N,but indirectly by concentrationsof Cl^-,CO₃^2-,HCO₃^-,Na⁺,K⁺,Ca²⁺,Mg²⁺,water-soluble salt and organic matter.AMFcolonization rate was negatively related with soil pH and concentrations of HCO₃^-and CO₃^2-.AMF colonization rate was affected directly by concentrations of Cl^-,CO₃^2-,K⁺,Ca²⁺andorganic matter,but indirectly by soil pH and concentrations of SO₄^2-,HCO₃^-,Na⁺,Mg²⁺,water-soluble salt,Olsen-P,Olsen-K and Olsen-N.The species richness and dominant speciesof AMF differed in rhizospheres of plant species.AMF species richness of saline soils,alkaline soils and salinized warped irrigation soils was 24,18 and 17,respectively.There wasno difference in dominant AMF genera or species among soil types.Soil properties werelinked to the biodiversity,species richness and relative abundance of AMF.4.VA mycorrhizae(Glomus mosseae)enhanced the ability of maize plants to cope withsalt stress.This may be because VA mycorrhizal symbiosis(1)triggered the regulation of theenergy biturcation between photochemical and non-photochemical events;(2)increased dryweight of shoot and root,water use efficiency,water content,relative chlorophyll content,netphotosynthetic rate,stomatal conductance,transpiration rate,photochemistry efficiency,non-photochemistry efficiency,root activity,average root diameter,root volume,CAT activity,and contents of reducing sugars,soluble sugars,soluble protein and free organic acid;(3)decreased water saturation deficit,intercellular CO₂ concentration,Fo,root to shoot ratio,specific root length,percentage of root length in 0～0.2 mm diameter class,the electricalpermeation rate,and contents of O₂^-,H₂O₂ and MDA.5.Microbiological diversity significantly differed in soil type of Saskatchewan,Canada.Among soil type,there was the highest biomass of total microbe,AMF,non-AMF fungi andG⁺ bacteria in Vertisol,and the highest fungi/bacteria ratio and fungal relative abundance inBrown Chemozem.The fungal biomass and fungi/bacteria ratio were positively correlatedwith Cu²⁺content,but negatively with the average precipitation of July and August andcontents of Olsen-N,Mn²⁺,Zn²⁺and organic matter.The biomass of G⁺ bacteria waspositively related with Olsen-P content,but negatively with soil bulk density.The biomass ofG bacteria was negatively related with Olsen-P content,but positively with soil bulk density.The biomass of AMF was positively correlated with the average precipitation of May and theaverage temperature of May,June,July and August,but negatively with the averageprecipitation of August,soil bulk density and concentrations of Mn²⁺and Zn²⁺. Totally,four AMF species(Glomus mosseae,G.hoi,G.sp.1 and G.sp.2)were identifiedfrom 49 farmland soil samples.G.sp.1 and G.hoi mostly distributed in Grey Luvisol;G.mosseae mostly in Dark-Brown Chernozem;G.sp.2 mostly in Dark-Grey Chernozem.Thedistribution of G.hoi in soil was related to Cu²⁺content and the average temperature of May,June,July and August;G.mosseae was linked to soil bulk density and the averageprecipitation of May,June,July and August;G.sp.1 and G.sp.2 was related to concentrationsof Olsen-N,Olsen-P,Mn²⁺,Zn²⁺and organic matter.Two models were built to figure out the relationship among AMF,soil properties andcontents of N and P in wheat plants.Y₁=1.36350-0.00132X₁₁+0.06304X₁₂-1.64599X₁₃+18.39645X₁₄Model 1Y₂=0.27405-0.00014X₂₁-0.01429X₂₂+0.00184X₂₃Model 2...