Behavior of BAS-9052 OH in Soybean (Glycine max) and Johnsongrass (Sorghum halepense) Plant and Cell Cultures

Abstract

Research involved the behavior of BAS-9052 OH {2[1-(ethoxyimino)butyl]-5-[2(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} in soybean [Glycine max (L.) Merr.] and johnsongrass [Sorghum halepense (L.) Pers.] plants, and the fate of 14C-BAS-9052 OH in intact plants and cell cultures of both species. Microscopic examination of seedling johnsongrass plants (two- to three-leaf stage) treated with foliar applications of 0.48 μg/plant revealed disorganized apical regions and necrotic cells within the apex and leaf primordia of the shoot. Necrotic zones were also evident at the base of expanding leaves and in root apices 1 day after treatment. Following application of 14C-BAS-9052 OH, the same radioactive products were isolated from cell cultures and intact plants. Products included BAS-9052 OH and three unidentified metabolites. Greater proportions of unchanged BAS-9052 OH were extracted from the apical leaves, roots, and cell cultures of johnsongrass than of soybean. BAS-9052 OH was thermal and photo-labile, and a large portion of 14C may not have entered the plant as BAS-9052 OH. However, tolerant soybean plants and cell cultures appeared to have metabolized the herbicide more rapidly than susceptible johnsongrass plants and cell cultures. An average of 64% of the 14C remained in the treated leaf of johnsongrass compared with 48% in soybean. About one-half as much 14C was translocated to the apical leaves of susceptible johnsongrass than tolerant soybean. Therefore, differential uptake and translocation cannot account for the selectivity of BAS-9052 OH.