Produção Científica // Artigos

BACKGROUND: Soybean (Glycine max) is an important oleaginous legume that has been cultivated in new areas in Brazil,including pastures. Problems of reduced production yields have been reported by soybean growers when the crop is sownimmediately after desiccation of pastures of Urochloa spp. using glyphosate. The objective of this work was to extract, isolateand identify the major chemicals from U. ruziziensis that have phytotoxic activity and to evaluate the possible relation betweenthis e?ect and reduced soybean yield.RESULTS: U. ruziziensis plants at the ?owering stage were desiccated using glyphosate at 1.44 kg ha?1 . The plants were collectedbetween ?ve and ten days after treatment. Extracts of dried and ground shoots were obtained by sequential extraction withhexane, dichloromethane and methanol. The results of wheat coleoptile bioassays indicated that the methanol extract was moreinhibitory than the dichloromethane extract regardless of glyphosate application.CONCLUSION: Protodioscin, a steroidal saponin, was isolated from the extract as the major component and the activities of thiscompound were in good agreement with those found for the extract. The release of this compound into the soil is a plausibleexplanation for the decrease in production observed in transgenic soybean crop after desiccation of U. ruziziensis.