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期 刊 ：植物保护学报 2007年

关键词：水稻恶苗病菌；浸种剂；抗药性；竞争力；

Keywords:Fusarium moniliforme, fungicides for seed-treatment, fungicide resistance, competition ability,

摘 要 ：从江苏13个地区采集病样,并分离获得水稻恶苗病菌Fusarium moniliforme 548个菌株,检测其对多菌灵、咪鲜胺和浸种灵等三种浸种剂的抗性及抗药菌株的竞争力。结果发现,以10μg/mL(MIC)为检测标准,抗多菌灵菌株频率平均为95.8%,其中高抗菌株(MIC>100μg/mL)占82.7%,少数高抗菌株EC₅₀>1000μg/mL,且抗性稳定;菌株敏感性频率分布法测定水稻恶苗病菌对咪鲜胺的敏感基线为(0.00075±0.00003)μg/mL(EC₅₀)和0.85μg/mL(MIC),以3μg/mL(MIC)为检测标准,抗咪鲜胺菌株有8个,抗性菌株频率平均为1.5%,且均为高抗(抗性倍数103.1~126.2)或中抗(抗性倍数24.6~95.0)水平,但经转管培养5~20代后菌株抗性显著下降;以同样方法测定水稻恶苗病菌对浸种灵的敏感基线为(1.265±0.014)μg/mL(EC₅₀)和3.13μg/mL(MIC),以5μg/mL(MIC)为标准,未检测到抗浸种灵菌株。此外,抗、感菌株分生孢子等量混合液接种结果表明,抗多菌灵菌株在水稻上竞争力较强,而抗咪鲜胺菌株竞争力较弱。

Abstract:Five hundred and forty-eight strains of Fusarium moniliforme causing rice bakanae disease were isolated and obtained, from 13 areas of Jiangsu Province, China. The resistance of these strains to three fungicides used for rice seed treatment and the competition of the resistant strains were studied. According to the discriminatory concentration in PSA amended with carbendazim of 10μg/mL (MIC), the mean ratio of carbendazim-resistant strains was 95.8% and the highly resistant ones (MIC>100μg/mL) accounted for 82.7%, in which EC₅₀ values of a few strains were more than 1000μg/mL. The resistance to carbendazim was stable after these strains were 20 times transferred on carbendazim-free PSA. The sensitivity baseline of the pathogen to prochloraz was (0.00075±0.00003)μg/mL (EC₅₀) and 0.85μg/mL (MIC) according to the frequency distribution of EC₅₀ and MIC values of 30 wild isolates. Based on the discriminatory concentration in PSA amended with prochloraz of 3μg/mL (MIC), 8 strains resistant to prochloraz were found, with the average ratio of 1.5%. The resistance of these strains to prochloraz was high or moderate, with the resistance factor (EC₅₀^R/EC₅₀^S) of 103.1-126.2 fold and 24.6-95.0 fold, respectively. But the resistance to prochloraz decreased significantly after the strains were 5-20 times transferred. The sensitivity baseline of the pathogen to diisothiocyanatomethane was determined to be (1.265±0.014)μg/mL (EC₅₀) and 3.13μg/mL (MIC) by the same method. No strains resistant to diisothiocyanatomethane were found according to the detection on the medium supplemented with 5μg/mL (MIC) of the fungicide. The result of inoculation with mixed conidia (1∶ 1) of resistant and sensitive strains showed that the carbendazim-resistant strains had stronger competition ability than the sensitive ones on rice plants, while the resistant strains to prochloraz had lower competition than the sensitive ones.

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