Environmental Effects on Absorption and Translocation of 2,4,5-T in Winged Elm

Abstract

The absorption and translocation of foliarly applied14C-labeled (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T-1-14C) in winged elms (Ulmus alataMichx.) as affected by season of application, air temperature, and soil moisture were determined by autoradiography of bark samples and liquid scintillation counting of leaf tissue. Treatments at 3-week intervals throughout the growing season showed highly variable trends in absorption and translocation within and between growing seasons. Seasonal variations in the absorption of14C-2,4,5-T were similar to the variations in translocation. Translocation into the stem closely correlated with absorption into the leaves. Higher daily temperatures of 24 to 40 C appeared to enhance absorption and translocation. Variations in soil moisture showed little effect on absorption; whereas, a decrease in soil moisture reduced translocation from leaves to roots.