Greenhouse studies were conducted to evaluate 14C-glufosinate absorption, translocation, and metabolism in glufosinate-resistant corn, goosegrass, large crabgrass, and sicklepod. Glufosinate-resistant corn plants were treated at the four-leaf stage, whereas goosegrass, large crabgrass, and sicklepod were treated at 5, 7.5, and 10 cm, respectively. All plants were harvested at 1, 6, 24, 48, and 72 h after treatment (HAT). Absorption was less than 20% at all harvest intervals for glufosinate-resistant corn, whereas absorption in goosegrass and large crabgrass increased from approximately 20% 1 HAT to 50 and 76%, respectively, 72 HAT. Absorption of 14C-glufosinate was greater than 90% 24 HAT in sicklepod. Significant levels of translocation were observed in glufosinate-resistant corn, with 14C-glufosinate translocated to the region above the treated leaf and the roots up to 41 and 27%, respectively. No significant translocation was detected in any of the weed species at any harvest timing. Metabolites of 14C-glufosinate were detected in glufosinate-resistant corn and all weed species. Seventy percent of 14C was attributed to glufosinate metabolites 72 HAT in large crabgrass. Less metabolism was observed for sicklepod, goosegrass, and glufosinate-resistant corn, with metabolites composing less than 45% of detectable radioactivity 72 HAT.
Nomenclature: Glufosinate, goosegrass, Eleusine indica L. Gaertn., large crabgrass, Digitaria sanguinalis L.; sicklepod, Senna obtusifolia (L.) H.S. Irwin & Barneby.; corn, Zea mays L