| Bringing huge economic benefits,coal mining produces a large number of coal waste fly ash in large scale at the same time,which leads to large areas of lands subsidence and damages the local ecological environment seriously.It is one of effective ways that fly ash is used to reclamate subsidence areas and reconstruct vegetation to solve the coal mine area ecological destruction and environmental pollution.Arbuscular mycorrhizal fungi could promote plant to absorb mineral nutrition and water,which enhances the resistance of the plants under adversity environment.Thus it could give benefits to plant growth and development in mining subsidence land,accelerate the recovery of ecological environment in mining area.In my dissertation,I used potted plant experiment to simulate the reclamation effect on different thickness of fly ash filling with subsidence area.The FA with depth of 3,5,and 7 cm was placed in the bottom part of the pots.Then,above the FA were covered with sterilized soil with depth of 9,7,and 5 cm respectively.Therefore,the total depth of growth substrate remained as 12 cm for all the treatments.A perennial herb plant,alfalfa(Medicago sativa L.),was used as a target plant in this study.The AMF species were Glomus mosseae and Glomus versiforme and a mixture of both AMF species for inoculation treatment,with using the unvaccinated treatment as a control.It is the basis that the effect of plant reclamation is improved in coal mining area on the theory of mycorrhizal technology.The main results were obtained as follows:1.The symbiotic associations,between AMF and alfalfa,were successfully established in various soil depths and had a higher infection rate in the treatments.The highest infection rate up to 45.89% in the soil depths of 9 cm,also the mycorrhizal dependency is the largest.Compared to the control,inoculation of AMF significantly promotes the growth of the plant.It is striking especially in soil depths of 5 cm,including plant heights,plant biomass and so on.AMF also increased chlorophyll content,extended the life of the leaves and improved the chlorophyll fluorescence effect via increasing fluorescence indicators of Fv/Fm,Fv/Fo,qP,Yield and decreased NPQ,which would relieve oxidative stress of coal fly ash and maintain the photosynthesis successfully.2.Compared to uninoculated contrast,all the AMF had improved the content of soluble sugar and soluble protein of plant leaves,and reduce plasma membrane relative permeability.The results show that the inoculation of AMF can alleviate the osmotic stress and biological membrane damage of alfalfa suffered from fly ash.The phenomenon would enhance plants surviving in coal mining districts.In various soil depths,soil depths significantly affect the osmotic regulation substances of plant,osmotic stress enhanced with the soil depths reducing.Soluble sugar and soluble protein were the common indicators to reflect the plant health level.3.All the AMF inoculation treatments significantly increased SOD,POD,CAT activities and ASA content,meanwhile,H2O2 content,MDA content and rates of O.-2were significantly decreased compared to non-inoculated treatment.Suggested that inoculation of AMF can improve the alfalfa antioxidant enzymes activity and antioxidant content,which would enhance the plant ability to remove active oxygen,help to relieve the oxidative stress suffered from fly ash and enhance its resistance to adversity.In various soil depths,soil depths significantly affect the resistance of plants suffered from fly ash,relatively,the resistance of alfalfa declined with the soil depths reduced.4.Compared with non-inoculated controls,all the AMF inoculation treatments significantly increased TTC activities,and changed root morphology that showed different mycorrhizal dependence,such as increased root length,root surface area,root volume,root tips number and decrease root average diameter.At the same time,the formation of mycorrhizal enhance the alfalfa ability to absorption of N,P elements,which would enhances alfalfa adaptive capacity that via improved the mineral nutrition conditions under the adverse environment that suffered from coal fly ash.In various soil depths,soil depths significantly affects the growth of plant roots,roots growth of alfalfa was inhibited with the soil depths reduced.5.In this experimental,the mixed fungi promoting effect for alfalfa growth were more significant than the single fungus Glomus mosseae and Glomus versiforme,demonstrated that mixed fungi can make up the shortage of a single fungus and generated positive effects on alfalfa biophysiology. |
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