Accumulation of Ammonia in Plants Treated with Bialaphos

Abstract

An increase free ammonia content was confirmed in Japanese barnyard millet (Echinochloa utilis ohwi), crabgrass (Digitaria adscendens henr.), livid amaranth (Amaranthus lividus L.) and purple nutsedge (Cyperus rotundus L.) treated with bialaphos, L-2-amino-4-[(hydroxy) (methyl) phosphinoyl]butyryl-L-alanyl-L-alanine. The ammonia content reached about 30 to 100 times higher than the control's in 24 to 48 hr after the treatment. The increment was more marked in shoots than in roots of the barnyard millet, and more in leaves than in stems of livid amaranth. The accumulation was not momentary, but persistent until the death of the plant. Such a remarkable accumulation of ammonia was not observed in plants treated with any other herbicide. Therefore, the ammonia accumulation is considered to be a particular action caused by bialaphos. The close correlation between the free ammonia content and the herbicidal activity indicated that the toxicity of accumulated ammonia is a primary factor to the herbicidal activity of bialaphos. © 1986, Pesticide Science Society of Japan. All rights reserved.