Mechanisms Of Soil Microbial Degradation To Allelochemicals Of Invasive Plant Eupatorium Adenophorum

Eupatorium adenophorum Sprengel is the most invasive weed in China and has caused enormous loss to agriculture,the livestock industry and the environment.This review focuses on E.adenophorum biological characteristics,invasion mechanisms,ecological effects of invasions,and controls and utilizations,and summarizesthe progresses ofresearchon E.adenophorum over the past decade.We review reproduction and p he no logical characteristics of E.adenophorum,whic h illuminates the physiological factors that could benefit its expansion.Then,we summarize the molecular,biological and chemical mechanisms of E.adenophorum invasion,and clarifyits effect on microorganisms and soil biological and chemical properties.WeSummarize the research on controls,replacements and utilizations of E.adenophorum.E.adenophorum invasion has a great relationship with the allelochemicals it release,allelochemicals can change the soil microbial community structure and its physical and chemical properties,which is conducive to its invasion.There are also has bacteria can degrade the allelopathy in soil,which can reduce the inhibitory effects of allelochemicals on native plants.Therefore,The key of this study is to restoring the ecological balance of the invasionplace by weakening or eliminating the allelopathic effect tonative plants,to the plants that have been successfully invaded by allelopathy.In this study,the strain was screened out from the soil of E.adenophorumserious invasion area,measure and verifyits degradation effects.The results of thisresearch are:1.From the E.adenophorum invasionplace in panzhihua,SichuanProvince,China.We collect the whole E.adenophorum plants,only cut its stems and leaves to extract with water of 36h,successfully extracted two main allelochemicals:9-Oxo-10,11-dehydroageraphorone and 9?-Hydro xyageraphorone,explore and optimize the process of allelochemicals extraction.2.Soil samples were collected from Lancang,Yunnan,China.We usedtwo allelochemicals as carbon source,screened eight strains candegradeE.adenophorumallelochemicals by culture tracing method.Then we determin the 16S rDNA sequence of strainsand prepared phylogenetic tree using Mega 5.0 to identify this eight strains belong to six different genus:N1 was Pseudomonas,N2,N5 is Klebsiella,N3 is Rhizobium,N4 is Enterobacter,I1,I2 is Sphingobacterium and 13 Is Novosphingobium.3.The culture conditions ofstrain degradation were:30 ?,150r/min,the inoculation amount is0.5ml and the degradation time was 48h.The results showed the degradation rate of N1,11 was 10%?20%when the concentration of allelochemicals was lOppm and 40ppm.The degradation rate of N3 was less and the lowest was 0.6%,the highest wasabout 10%.The degradation rate ofI2,I3 is low,part of the degradation rate is negative may be relate to the systematic error.The degradation rate of N2,N5 is better when the concentration of allelochemicalsis 40ppm,the degradation rate of N4 is poor.4.In order to verify the degradation effect of strain on allelochemicals of E.adenophorum,we selected Triticum aestivum L.and Trifolium repensas the tested seeds,added the bacterial and allelochemicals to culture dish to observe the seeds root length,shoot length,germination rate,dry weight and fresh weight.The results showed that Triticum aestivum L.growth and germination were not sensitive to allelochemicals,and Trifolium repenswere sensitive in germination rate,fresh weight and dry weight.