Absorption and Translocation of Buthidazole

Abstract

Absorption and translocation of buthidazole [3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone] was determined in several plant tissues. Buthidazole caused slight effects on seed germination. Germination of soybean (Glycine max L. Merr. ‘Williams’) seeds was inhibited up to 15% and velvetleaf (Abutilon theophrasti Medic.) was stimulated up to 13%. Buthidazole was absorbed by germinating soybeans, velvetleaf, and corn (Zea mays L.) with rate of absorption increasing when roots were capable of absorption. Buthidazole concentrations of 0.5 μM or greater inhibited growth of soybean in the early second-trifoliolate growth stage when supplied to the roots in nutrient solution. Within 96 h, 29% of the buthidazole available to soybeans was absorbed from nutrient solution and 89% of that absorbed was found in the shoots. The expanded leaves of soybean accumulated the majority of the radioactivity. Radioactivity in roots of soybean approached a steady state condition within 96 h, whereas ¹⁴C continued to increase in shoots. Foliar absorption of buthidazole in soybean greatly increased when any one of several surfactants were used. Soybean dry weight reduction nearly doubled by adding surfactants. Over 60% of the ¹⁴C-buthidazole applied to soybean leaves was absorbed within 1.5 h, and increased to 73% by 96 h when the nonionic surfactant, AL-411-F³ [Phytobland Spray Oil (83%) plus ATPLUS 300F (17%)] was used compared to only 7% in 96 h without the surfactant. There was little or no movement of buthidazole from the treated leaves. Translocation was typical of apoplastic movement.