Phytotoxicity, uptake, and distribution of [C-14] simazine in Canna hybrida 'Yellow King Humbert'

Phytoremediation depends on the ability of plants to tolerate and assimilat e contaminants. We have been interested in the use of common ornamental pla nts to ameliorate the impacts of pesticide waste on golf courses and orname ntal plant nurseries. This research characterized the interaction between a n ornamental, Canna hybrida 'Yellow King Humbert,' and the herbicide simazi ne. Simazine tolerance levels for C. hybrida were determined by exposing pl ants for 7 d to 0, 0.01, 0.03, 0.1, 0.3, 1.0, or 3.0 mg-simazine/L aqueous nutrient media. Response endpoints included fresh mass production after 7 d of exposure and 7 d postexposure and quantum efficiency using dark-adapted and light-adapted plants. Simazine uptake and distribution within the plan t was determined by exposing plants to 2.02 mu Ci [C-14]simazine in nutrien t media (0.242 mg/L) for 1, 3, 5, or 7 d. Plant tissues were combusted and analyzed by liquid scintillation counting. Fresh mass production was reduce d 66 and 78% for plants exposed to 1.0 and 3.0 mg/L, respectively. Photosyn thetic efficiency measured in dark-adapted plants was reduced 34 and 60% at the same respective concentrations, whereas photosynthetic efficiency meas ured in light-adapted plants was reduced 76 and 92%, respectively. Simazine activity in solution was reduced 80% over 7 d. By day 7, simazine (and/or an impurity) was distributed throughout the plant, but predominantly occurr ed in the leaves. Uptake of simazine was correlated with water uptake throu ghout the 7 d. These results suggest that C. hybrida may be a good candidat e for incorporation into a phytoremediation scheme for simazine.