Disseminação endozoocórica, germinação e controle de Lolium multiflorum Lam. resistente a herbicida inibidor da enzima EPSPs

Abstract

Annual ryegrass (Lolium multiflorum Lam.) is a winter grass in southern Brazil with annual cycle, used for the production of ground cover on tillage and as forage. This species is highly dispersed, and no-till areas, glyphosate herbicide is widely used for its management. Therefore, the objective of this study was to evaluate the endozoochorus dissemination, germination and control of L. multiflorum resistant to EPSPs enzyme inhibitor herbicide. Seeds (25 g, 12.112 seeds) were offered through a tube into the rumen of six calves were kept in metabolic cages for testing. It was performed germination in seeds recovered in the feces and seeds that have not passed through the digestive tract, and, subsequent application of glyphosate at different doses to evaluate the resistance of plants (0, 1, 2, 4, 8, 16 and 32 times the recommended dose). Seeds provided to the animals, 9.1% were recovered in the faeces. Those first three days recovered corresponding to 92.6% of the total amount of seed recovered. The absence of ryegrass seeds occurs in the faeces from the eighth day after ingestion. The germination of seeds recovered was lower compared to the germination of the control (66%) after 44 and 72 h, the germination was 41 and 32% respectively. For seed recovered 96 h after, germination was 21%. The residence time in the gastrointestinal tract influences the reduction of the germination of ryegrass seed. Up to eight times the recommended dose of herbicide, there was only 50% of the control over the plants. So, to avoid endozoochorus dispersion of an area with resistant biotypes glyphosate to areas free of ryegrass infestation, calves should be quarantined for eight days to complete elimination of the seeds of the digestive system. Furthermore, the management inefficient with this herbicide remains even after the seeds passing through the rumen.