Factors Affecting the Translocation of14C-Mefluidide in Soybeans(Glycine max), Common Cocklebur(Xanthium pensylvanicum), and Johnsongrass(Sorghum halepense)

Abstract

Absorption and translocation of 14C-mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} in soybeans [Glycine max (L.) Merr. ‘Lee 68’], common cocklebur (Xanthium pensylvanicum Wallr.), and johnsongrass [Sorghum halepense (L.) Pers.] were evaluated under different environmental conditions with and without adjuvants. At a constant level of 40 or 100% relative humidity (RH), an increase in air temperature from 22 to 32 C resulted in a two- to three-fold increase in absorption and a four- to eight-fold increase in translocation of the 14C in soybeans following application to the second trifoliolate. At constant 22 or 32 C an increase from 40 to 100% RH resulted in less than a two-fold increase in absorption or translocation of 14C in soybeans. Autoradiograms indicated that movement of the 14C was primarily into leaves above the treated area. Translocation of 14C was significantly greater following application to the lower stem than to leaves. In common cocklebur, 14C absorption increased about three-fold at both 22 and 32 C with an increase from 40 to 100% RH following application to the second alternate leaf. At both levels of RH, absorption and translocation increased as the temperature was increased from 22 to 32 C. The addition of an adjuvant increased absorption and translocation in common cocklebur under all environmental conditions. When 14C-mefluidide was applied without an adjuvant to johnsongrass, absorption increased five- to six-fold at both 22 and 32 C as RH was increased from 40 to 100%. Translocation in johnsongrass was often affected less by variations in temperature than it was in soybeans or common cocklebur. The adjuvant increased absorption and translocation of the 14C-label of mefluidide in johnsongrass. The 14C-label accumulated primarily in the distal leaf of johnsongrass or in leaves above the treated area.