The Diversity Of Arbuscular Mycorrhizal Fungi In Degraded Grassland Soil In Hulunbuir And The Research Of Microbial Remediation

Grassland is one of the world’s most widely distribution of vegetation types and important component of the terrestrial ecosystem.At present,because of the long-term extensive management, overgrazing,overload and the unreasonable development and utilization of grassland, the biological diversity of grassland vegetation and the stability of the grassland ecosystem were under threat and the grassland degradation is very serious.Arbuscular mycorrhizal(AM) fungi play a important role in regulating the composition of plant communities,which is great signifitant to maintaining the stability of the ecosystem.The hulunbuir degraded grassland was the research object.We firstly investigated the AM fungal diversity of different degradation degree of hulunbuir grassland soil and AM infection rate of grass-root,trying to explain this change from the soil factor aspect. Trying to remediate by AM fungi.The result of greenhouse experiment and natural pasture experiment indicated that the improver’s great impact to the soil and the plant growth.The main experimental results are as follows:Soil moisture content,soil aggregate structure degradat,total carbon content, soil urease activity declined significantly with the degree of grassland degradation. Soil p H and EC value significantly increased with the increase of the degree of grassland degradation.Soil effective phosphorus content, soil invertase activity and alkaline phosphatase activity had the following trend,Light degradation > No degradation >Moderate degradation > Highly degradation. AM infection rate of grass-root significantly decreased with the increase of the degree of grassland degradation,and the AM infection rate of grass-root was significantly positive correlation to soil moisture content, urease activity and was significantly negative correlation to soil p H and EC value.Amplifing segments of AM fungi fragment from soil DNA and used DGGE technology analysing the AM fungi diversity,by denaturant gradient range of30%-50%.The results showed that AM fungi diversity index,richness and evenness had following trend,Light degradation > No degradation > Moderate degradation >Highly degradation.They were significant positive correlation to soil effective phosphorus and alkaline phosphatase activity and they were significant negativecorrelation to had a was significantly positively related, were very extremely significant positive correlation to sucrose enzyme activity.Remeidating the degradated grassland soil with AM fungi,humic acid and JD37 common,and explored its improvement effect on soil and plants.Preliminary experimental results showed that soil improvement effect was better when AM fungi combined with mass fraction of 0.15% humic acid or diluted multiples of 100 JD37 fermented liquid.The following experiment uesd these three components worked together in remeidating the degradated grassland soil.According to the results of soil physical,chemical,biological propertie and grass biomass,mycorrhizal infection rate were significantly improved.Selected the peat which diameter lime less than 0.3 mm as JD37 adsorption carrier,and developed microbial improver with AM fungi and humic acid.In use of microbial improver under greenhouse conditions,the degradated grassland soil showed great effect after two months.The soil p H was significant reducted and alleviated the harm of high salinity in the soil.The soil physical, chemical and biological properties were significantly increased.The forage grass growth had a significant promoting.Doing the situ-repair in continuous grazing district and banning grazing district of natural degradated pasture,and set the modifier large-dose treatment(80 kg/mu)and small-dose(60 kg/mu) treatment.The experimental results showed that control of continuous grazing district had low fertility of soil and vegetation. Application modifier small-dose treatmen and considering grazing disturbance the effect was not very obvious.But the large-dose treatment had significant difference to control.The banning grazing district had certain repair effect due to the fence,and the degree of degradation was abate,the small-dose group had ideal repair effect.These findings were for understanding and using of AM fungi in the soil and applying this microbial improver to the marketing and practical application in the future contaminated soil in future research and they had great significance to grassland sustainable development.