Herbicide Resistant Weeds

Fate of atrazine in treated and pristine accessions of three Setaria species.

Gimenez Espinosa, R., E. Romera, M. Tena, R. Prado de, and R. De Prado. 1996. Fate of atrazine in treated and pristine accessions of three Setaria species. Pesticide Biochemistry and Physiology. 56: 196-207.

Experiments were conducted to compare the effects of atrazine on Setaria adherens [S. adhaerens], S. glauca [S. pumila] and S. verticillata from populations not controlled by previous exposure to triazines and from populations without a history of exposure. Results of bioassays indicated that there was no difference in the susceptibility of the S. adherens and S. verticillata populations, but the S. glauca exposed population was 5 times less susceptible than the other species, while its unexposed population was 6 times more susceptible. No differences were found between populations in atrazine uptake or translocation. Chlorophyll fluorescence analysis of isolated plastids indicated that those from the exposed S. glauca population had less affinity for atrazine than those from the unexposed population. No differences were found between populations of the other species. The exposed S. glauca population was resistant to a wide range of triazines and photosystem II inhibitors, while both populations of the other 2 species showed resistance to chloro-s-triazines and conjugated >80% atrazine. Atrazine-specific glutathione transferase had a higher activity in S. verticillata than S. glauca.