Mefenpyr-diethyl action on fenoxaprop-p-ethyl detoxification in wheat varieties A o de mefenpyr-diethyl sobre a desintoxica o de fenoxaprop-′p-ethyl em variedades de trigo

Safeners protect crops against herbicide injury. The aim of this study was to examine the differential susceptibility of five wheat (Triticum aestivum) varieties to the herbicide fenoxaprop-p-ethyl, as well as the performance of mefenpyr-diethyl on minimizing herbicide injury and on lipid contents. Varieties BRS 49, CD 104, CEP 24, IAPAR 78 and Rubi were sprayed with fenoxaprop-p-ethyl (69 g ha1), fenoxaprop-p-ethyl + mefenpyr-diethyl (69 g + 18.75 g ha-1), or mefenpyr-diethyl (18.75 g ha-1). Plants were evaluated visually for injury at 7 and 14 days after treatment (DAT). Glutathione S-transferase (GST) activity was assayed in aerial parts at 7 DAT, and lipid content was measured at 14 DAT. Varieties CEP 24, IAPAR 78 and Rubi were more tolerant to fenoxaprop-p-ethyl than BRS 49, and CD 104 rapidly recovering from the slight phytotoxicity symptoms produced by the herbicide. Mefenpyr-diethyl prevented crop injury associated with the herbicide. GST activity did not correlate directly with fenoxaprop-p-ethyl detoxification. However, lipid content was related to the susceptibility of wheat to fenoxaprop-p-ethyl treatment. Protetores ou safeners protegem culturas contra a injúria de herbicidas. O propósito deste estudo foi investigar a suscetibilidade diferencial de cinco variedades de trigo (Triticum aestivum) ao herbicida fenoxaprop-p-ethyl e o efeito do protetor mefenpyr-diethyl na minimiza o da injúria do herbicida e sobre o conteúdo de lipídios. As variedades BRS 49, CD 104, CEP 24, IAPAR 78 e Rubi foram pulverizadas com fenoxaprop-p-ethyl (69 g ha-1), fenoxaprop-p-ethyl + mefenpyr diethyl (69 g + 18,75 g ha1) ou mefenpyr-diethyl (18,75 g ha1). A injúria das plantas foi avaliada visualmente aos 7 e 14 dias após o tratamento (DAT). A atividade da glutationa S-transferase (GST) foi analisada na parte aérea aos 7 DAT, e o conteúdo de lipídios, aos 14 DAT. As variedades CEP 24, IAPAR 78 e Rubi foram mais tolerantes ao fenoxaprop-p-ethyl do que a BRS 49, e a variedade CD 104 rapidamente se recuperou dos sintomas de intoxica o produzidos pelo herbicida. Mefenpyr-diethyl preveniu a injúria da cultura pelo herbicida. A atividade da GST n o foi correlacionada diretamente com a desintoxica o do fenoxaprop-p-ethyl. Contudo, o conteúdo de lipídios esteve relacionado à suscetibilidade de trigo ao tratamento de fenoxaprop-p-ethyl.