中文摘要：

【目的】通过筛选和鉴定香蕉枯萎病的致病菌株,之后接种不同浓度的病原菌孢子悬液,研究香蕉植株的发病程度,以期为香蕉枯萎病的田间诊断提供科学的理论依据。【方法】采用室内筛选和盆栽试验相结合的方法。【结果】从香蕉枯萎病病株的假茎基部分离筛选纯化获得了一株致病的尖孢镰刀菌菌株。盆栽回接该菌株35d后,有90%香蕉植株发病,香蕉死亡率高达70%,经鉴定确认该菌株为香蕉枯萎病致病菌（Fusarium oxysporum f.sp.cubense,FOC）;本试验条件下,致病菌株的孢子悬液浓度为103CFU/g土时是香蕉枯萎病发病的临界浓度,当致病菌株的孢子悬液浓度不超过105CFU/g土时,香蕉枯萎病的发病指数随着病原菌孢子悬液浓度的加大而增加,当致病菌株的孢子悬液浓度超过105CFU/g土时,香蕉枯萎病的发病指数不再显著变化;香蕉根际土壤和土体土壤中的尖孢镰刀菌数量受致病菌株孢子悬液不同浓度的影响较大,接种病原菌孢子悬液不同浓度处理的根际土壤的尖孢镰刀菌数量是土体土壤尖孢镰刀菌数量的1.15—2.06倍,显著高于土体土壤尖孢镰刀菌数量。【结论】香蕉植株枯萎病是否发生与土壤本身的尖孢镰刀菌数量有关,发病程度高低决定于根际土壤中的尖孢镰刀菌数量,以上结果可为香蕉枯萎病的诊断提供科学的理论依据。

英文摘要：

Objective In order to provide a scientific basis for the field diagnoses of Fusarium wilt of banana,it is very important to screen and identify the pathogen which causes banana Fusarium wilt and to investigate the relationship between the spore suspension concentration and the disease incidence rate.Method A lab-screening and pot experiment was used to identify the pathogen.Result The pathogen isolated from the pseudo-crown of diseased banana showed a high pathogenicity in a pot experiment in which the disease incidence was 90% and mortality rate was as high as 70% 35 days after inoculation.A close relationship between the amount of inocula in soil and the disease incidence rate of banana wilt was found and the minimal concentration that induced the banana Fusarium wilt was 103 CFU /g soil.Disease incidence increased with the increase of inocula density in soil.Until the inocula density attained a certain degree（105 CFU/g）,the disease incidence would no longer increase.The numbers of pathogen in rhizosphere soil were 1.15 to 2.06 times higher than those in bulk soil in different treatments.A pot experiment was carried out to investigate the effects of a new bioorganic fertilizer（BIO） on banana plant growth and the suppression on the disease.It was found that the BIO bio-organic fertilizer contributed to the growth-promoting of banana plants and to the low occurences of fusarium-wilt disease.Conclusion It was related to background number of the pathogen in diseased soil that the banana Fusarium wilt occurred or not,while the disease incidence was mainly determined by the number of the pathogen in plant rhizosphere soil.These results would be served for the diagnosis of banana wilt.