MODE FOR HERBICIDAL ACTION OF 2-AMINO-3-CHLORO-1,4-NAPHTHOQUINONE (ACN)

The characteristic mode for the herbicidal action of 2-amino-3-chloro- 1,4-naphthoquinone (ACN) was investigated by using autotrophic green m icroalgae (Scenedesmus acutus). The effects of ACN on the growth, chlo rophyll content, protoporphyrin-IX accumulation, and ethane production in Scenedesmus cells were measured in comparison with three reference herbicides, i.e., ioxynil, dinoseb, and chlorophthalim. ACN appeared to have a different mechanism for action from these three herbicides. S. acutus cells grown with ACN produced ethane, but the mechanism for its production is considered to have been different from that of chlor ophthalim. ACN may inhibit porphyrin biosynthesis at a different stage from that by chlorophthalim.