EFFECT OF PICLORAM ON TRANSPORT IN YOUNG BEAN,MESQUITE, AND HUISACHE PLANTS

The effect of 4-amino,3,5,6-trichloropicolinic acid (picloram) on transport from leaves to the roots was studied using young bean (Phaseolus vulgaris L.), mesquite (Prosopis juliflora var. velutina (Woot.) Sarg.), and huisache (Acacia farnesiana (L) Willd.) plants. The only picloram treatments which were effective in enhancing transport of ¹⁴C-assimilate or ¹⁴C-picloram to the roots were those made to the shoots or roots one day or more before application of the label to the shoots. The enhancement of transport was not evident when un-labeled picloram or 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), or both, were applied at the same time as the ¹⁴C-label. Enhancement of transport was to the more mature stem or root tissues. Inorganic nitrogen applied to nitrogen-deficient bean plants also increased transport of ¹⁴C-assimilate to the roots, especially the rate.