Translocation of14C-SAN 6706 in Cotton, Soybean, and Corn

Abstract

The technique of microautoradiography was used to study the localization of14C-SAN 6706 [4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H-pyridazinone] in cotton (Gossypium hirsutumL. ‘Coker 203’), soybean [Glycine max(L.) Merr. ‘Lee’], and corn (Zea maysL. ‘W.F. 9’). SAN 6706 was removed from the treatment solutions by absorption and also by adsorption onto the surfaces of roots. Absorbed SAN 6706 appeared to move primarily in the apoplast and to be translocated acropetally and laterally in the transpiration stream. The herbicide accumulated in striking concentrations in the lysigenous glands and trichomes of the cotton plant. This accumulation is postulated to be a major factor in lowering the effective concentration of SAN 6706 in the leaves of cotton as compared to the leaves of the more susceptible soybean and corn plants, and thus may be a significant factor in the tolerance of cotton to SAN 6706.