Descripción: |
Avaliou-se o efeito de fungicidas na sobrevivência da bactéria Bradyrhizobium japonicum Semia 5019 e Semia 5079 e na nodulação em plantas de soja. Comparou-se, in vitro, a capacidade de multiplicação das bactérias em meio líquido YMA com duas concentrações dos fungicidas benomyl, carbendazim, carboxin+thiram, difenoconazole, thiabendazole+thiram, tiofanato metílico, captan, thiram, tolylfluanid, metalaxyl, fludioxonil+metalaxyl–m, carbendazim+thiram. A sobrevivência da bactéria foi medida por plaqueamento de diluições seriadas. Para ensaio em casa-de-vegetação, sementes da cv. ‘Embrapa 48’ foram tratadas com os fungicidas thiabendazole+thiram, metalaxyl, thiram, difenoconazole+thiram, carbendazim+thiram, fludioxonil+metalaxyl–m, tiofanato metílico+tolylfluanid, thiabendazole e captan. Utilizou-se o inoculante turfoso na proporção de 10 g/kg de sementes. Avaliou-se o número total de nódulos e na raiz principal. Constatou-se redução superior a 10% em relação à testemunha, na multiplicação de B. japonicum em meio com thiram, carbendazim, carboxin+thiram e carbendazim+thiram. Não se observou redução significativa de nodulação com os fungicidas testados, sendo que apenas para o fungicida captan o número de nódulos foi estatisticamente igual ao da testemunha não inoculada. The effect of fungicides on survival of Bradyrhizobium japonicum Semia 5019 and Semia 5079 and nodulation on soybean plants was evaluated in Brazil. The capacity of multiplication of bacteria in YMA liquid mean with two concentrations of benomyl, carbendazim, carboxin+thiram, difenoconazole, thiabendazole+thiram, thiophanate-methyl, carbendazim+thiram fungicides was compared in vitro. Survival of bacteria was measured by transferring of serial dilution in YMA mean. In greenhouse, seeds (cv. “Embrapa 48’) were treated with thiabendazole+thiram, metalaxyl, thiram, difenoconazole+thiram, carbendazim+thiram, fludioxonil+metalaxyl-m, thiophanate-methyl+tolyfluanid, thiabendazole and captan fungicides. Inoculant containing both bacteria strains was inoculated in a proportion of 10 g/Kg of seeds. Nodulation in soybean plants was measured counting the total number of nodules and those on the main root. Reduction over 10% was observed in relation to control in multiplication of B. japonicum in means containing thiram, carbendazim, carboxin+thiram and carbendazim+thiram. Tested fungicides did not affect nodulation. Only captan fungicide reduced the number of nodules in the main root when compared to control (not inoculated). |