为筛选出对胡萝卜黑腐病防治具有良好效果的放线菌，采用平板稀释涂布法、对峙培养法、生长速率法、盆栽试验和16S rRNA序列分析，对胡萝卜表层土中的放线菌分离、抑菌活性、盆栽防效和分类地位进行研究。结果表明，15株放线菌中仅菌株G-1对胡萝卜黑腐交链孢（Alternaria radicina）具有较好抑菌活性，其平板和发酵液抑菌率分别为77.2%、78.5%，显著高于其他菌株；经16S rRNA序列分析，将该菌株鉴定为微白黄链霉菌（Streptomyces albidoflavus）；盆栽防效以稀释50～100倍效果较好，可保持70%以上防效。综上所述，菌株G-1在胡萝卜黑腐病生物防治中具有良好应用价值。

 In order to screen out actinomycete with good inhibitory effect on Alternaria radicina,plate confrontation method,dual-culture inhibition method,growth rate method,pot experiment and 16S rＲNA sequence analysis were used to screen antagonistic actinomycete,test the control effect on Alternaria radic ina,and identify actinomycetes.The result showed that bothstrain G-1 and its fermentation broth had sig nificant inhibition rate against Alternaria radicina,and the inhibition rates were 77.2% and 78.5%,re spectively.Strain G-1 was identified as Streptomyces albidoflavus based on the analysis of 16S rＲNA se quence.In addition,the control effect of strain G-1 on Alternaria radicina was more than 70% in pot ex periment,when the fermentation broth of strain G-1 was diluted 50—100 times.In conclusion,strain G-1 had good application potential in controlling Alternaria radicina.