TRANSLOCATION, AND METABOLISM OF C-14 MSMA IN ORGANIC ARSENICAL-RESISTANT AND ARSENICAL-SUSCEPTIBLE MISSISSIPPI BIOTYPES OF COMMON COCKLEBUR (XANTHIUM-STRUMARIUM L)

The uptake, translocation, and metabolism of C-14-MSMA in organic arsenical-resistant (R) and -susceptible (S) Mississippi biotypes of common cocklebur were investigated, The two biotypes did not differ significantly with respect to either uptake, total translocation, or translocation pattern of C-14-MSMA plus its radiolabeled metabolites regardless of whether plants were pre-treated with 1.12 kg al ha(-1) of unlabeled MSMA or treated only with radiolabeled material, Absorption of C-14-MSMA was greater in unlabeled MSMA-pretreated plants than untreated plants, whereas the percent of total absorbed C-14-MSMA that was translocated out of the C-14-MSMA-treated leaf was almost the same in MSMA-pretreated and untreated plants, Qualitative detection of C-14-MSMA distribution by autoradiographs confirmed quantitative results obtained with radioassays, Herbicide metabolism in the C-14-treated leaf showed that MSMA was not readily broken down in both biotypes and the extractable C-14 was the same, Uptake, translocation, and metabolic degradation were not involved in the mechanism of resistance of the resistant-Mississippi biotype common cocklebur to MSMA.