RESUMO
The objective of this work was to evaluate methods to eliminate or reduce the number of indigenous arbuscular mycorrhizal fungi (AMF) from soil samples without affecting their edaphic or microbiological properties. At an early trial we evaluated moist heat (autoclaving), dry heat (oven), sodium hypochlorite (NaClO) and formaldehyde at a range of 100.0-3.3µl/g and 16.7-3.3µl/g respectively. There was no germination in plants of ryegrass (Lolium multiflorum Lam.) sown on substrates receiving NaClO (100.0-33.3µl/g), whereas autoclaving significantly increased the available soil phosphorous content. Both treatments failed to eradicate AMF colonization at 9 weeks; therefore, they were discarded. In a second trial, oven and formaldehyde (10.0µl/g) treatments were analyzed to assess the effects of seed decontamination and AMF reinoculation. Both procedures were effective in reducing or eliminating indigenous AMF at a range of soil P availability of 12-29mg/kg. However, the time between soil treatment and AMF multiplication and safety requirements were greater in the case of formaldehyde application.
Assuntos
Agricultura/métodos , Formaldeído/farmacologia , Fungicidas Industriais/farmacologia , Temperatura Alta , Micorrizas/isolamento & purificação , Hipoclorito de Sódio/farmacologia , Microbiologia do Solo , Fungos/efeitos dos fármacos , Fungos/isolamento & purificação , Umidade , Concentração de Íons de Hidrogênio , Lolium/microbiologia , Micorrizas/efeitos dos fármacos , Fósforo/análise , Raízes de Plantas/microbiologia , Solo/químicaRESUMO
El objetivo de este trabajo fue evaluar métodos para eliminar hongos nativos formadores de micorrizas arbusculares (HMA) o reducir su número en muestras de suelo, sin afectar sus propiedades edáficas y microbiológicas. Se estudió la aplicación de calor húmedo (autoclave), de calor seco (estufa), de hipoclorito de sodio (NaClO) y de formaldehído, en concentraciones entre 100,0 y 3,3 µl/g y 16,7 y 3,3 µl/g, respectivamente. Las semillas de raigrás (Lolium multiflorum Lam.) sembradas en sustratos que recibieron NaClO (100,0-33,3 µl/g) no germinaron y el autoclave incrementó el contenido de fósforo en el sustrato. Estos tratamientos no eliminaron la micorrización por HMA y ambos fueron descartados. En un segundo ensayo se analizaron los tratamientos estufa y formaldehído (10,0 µl/g), asociados o no a la descontaminación de las semillas y a la reinoculación con HMA. Ambos procedimientos redujeron o eliminaron la micorrización por HMA nativos en suelos con 12 a 29 mg/kg de fósforo y permitieron la multiplicación de inóculos de HMA. El tiempo de ventilación de las muestras y los requisitos de seguridad fueron mayores con la aplicación de formaldehído
The objective of this work was to evaluate methods to eliminate or reduce the number of indigenous arbuscular mycorrhizal fungi (AMF) from soil samples without affecting their edaphic or microbiological properties. At an early trial we evaluated moist heat (autoclaving), dry heat (oven), sodium hypochlorite (NaClO) and formaldehyde at a range of 100.0-3.3 µl/g and 16.7-3.3 µl/g respectively. There was no germination in plants of ryegrass (Lolium multiflorum Lam.) sown on substrates receiving NaClO (100.0-33.3 ul/g), whereas autoclaving significantly increased the available soil phosphorous content. Both treatments failed to eradicate AMF colonization at 9 weeks; therefore, they were discarded. In a second trial, oven and formaldehyde (10.0 µl/g) treatments were analyzed to assess the effects of seed decontamination and AMF reinoculation. Both procedures were effective in reducing or eliminating indigenous AMF at a range of soil P availability of 12-29 mg/kg. However, the time between soil treatment and AMF multiplication and safety requirements were greater in the case of formaldehyde application