Glufosinate metabolism in excised shoots and leaves of twenty plant species

The metabolism of the herbicide C-14-glufosinate (GA) was studied in excise d shoots and leaves of 20 weed and nonweed species; GA was fed through the xylem. After 24 or 48 h of incubation, the plant material was examined for phytotoxic symptoms, analyzed by autoradiography, and extracted. The extrac t was cleaned up and analyzed by high-performance liquid chromatography. GA and its metabolites were identified by cochromatography with authentic C-1 4-labelled reference compounds. C-14-GA was rapidly absorbed by the excised plant parts. Most of the radioactivity (91.3 to 99.7%) in the shoots and l eaves was extractable. The main metabolite observed with all species was 3- (hydroxymethylphosphinyl)propionic acid (MPP); lower amounts of 2-hydroxy-4 -(hydroxymethylphosphinyl)butanoic acid (MHB) were also found in 14 species . Metabolic rates of GA varied considerably ranging between 13.1 and 2,836. 5 ng GA h(-1) mg(-1) protein. The species with the highest rates of metabol ism of GA were Galium verum (2,836.5 ng GA h(-1) mg(-1) protein), Lythrum h yssopifolia (846.0 ng GA h(-1) mg(-1) protein), and Digitalis purpurea (494 .8 ng GA h(-1) mg(-1) protein). The mean value across all species was 275.9 ng GA h(-1) mg(-1) protein.