Autoradiography is a radioisotope-based technique that allows absorbed and translocated herbicide to be visualized. Autoradiographs are traditionally produced with X-ray film and exposure times of several weeks. Phosphorescence imaging (PI) was investigated as an alternative autoradiography procedure. Smallflower morningglory plants were root-exposed to a series of ¹⁴C-atrazine concentrations, producing a series of increasing foliar radioactivity concentrations (i.e., dosage) that ranged from marginal to excessive with respect to autoradiography. Autoradiographs were subsequently produced from these ¹⁴C-atrazine-dosed plants using both the X-ray film and the PI technique. Autoradiographs from both techniques were of excellent quality and nearly identical when the dosage was ∼20 to 70 Bq/mg. However, PI produces an acceptable image in dosages either above or below this optimum range. A 1-d exposure time was sufficient with PI, and longer exposure times were not detrimental to image quality. In contrast, a 3-wk exposure time was required with X-ray film. Autoradiographs of selected herbicides are presented to further demonstrate the utility of PI.

Nomenclature: Atrazine; smallflower morningglory, Jacquemontia tamnifolia (L.) Griseb IAQTA.