Study On Soil Microorganism Diversity Of Cotinus Coggygria Forest

Cotinus coggygria Scop. is a very important kind of ornamental tree species.In recent years,outbreak of Verticillium wilt which was caused by Verticillium dahliae Kleb.,not only lead to large deaths of C. coggygria. but also affected the landscape of Fragrant Hills Park seriously.But there are many difficulties in controlling Verticillium wilt.Therefore,we have studied the population and structure of soil and rhizosphere microorganism in the C. coggygria forest by the method of traditional isolation and cultivation.We have not just compared the number difference in rhizosphere and non-rhizosphere microorganism of healthy and infected C. coggygria,but the number difference of microorganism in healthy and infected C. coggygria forest. What's more,we found the change rules of soil microorganism and V.dahliae microsclerotia number of C. coggygria forest in Fragrant Hills Park.In addition,by traditional method and PCR-DGGE analysis method, we have also done some study on comparison of soil microorganism number of C. coggygria forest in Fragrant Hills Park,Yanqing,Shandong and Shaanxi.Through above analysis,we can understand the disease mechanism more clearly and provide the basic theory support for the control of Verticillium wilt. The conclusions were made as follow:1.The quantity of rhizosphere microorganism is greater than non-rhizosphere microorganism in healthy and infected C. coggygria.The number of rhizosphere and non-rhizosphere microorganism of healthy C. coggygria is also higher than the one in infected C. coggygria.But,the number of soil microorganism in infected C. coggygria forest is much higher than the one in healthy C. coggygria forest.2.Bacteria is the main microorganism type in the soil of C. coggygria forest.The number of soil microorganisms changed significantly from May to November. In the middle of July,the number of bacteria,actinomyces and sum of microorganism all reach their own peak.But the peak of fungi number appears in June. The number of soil microorganism is significantly different in different districts and the order is as follow:Yanqing>Shandong>Fragrant Hills Park>Shaanxi.The V.dahliae microsclerotia number of C. coggygria forest reach two peaks in June and September.3.Penicillium,Aspergillus,Trichoderma,Gliocladium and Fusarium are the dominant fungi population in the soil of C. coggygria forest.However,Fusarium and Trichoderma are the dominant fungi population in the rhizosphere soil of infected C. coggygria plant.We can isolate a large number of V.dahliae in the root of infected C. coggygria from June to August. The isolation frenquence of V.dahliae next to 100%.However,the isolation frenquence of V.dahliae will reduce rapidly from September to November and we can isolate many saprophytic fungi.4.Through PCR-DGGE analysis and diversity index analysis to the soil of C. coggygria forest in different districts,Fungi diversity of Yanqing is the most abundant in the soil of C. coggygria forest.