Abstract
Herbicidal compounds, N-(3, 4-dichlorophenylcarbamoyl)-N-methyl glycine·H2O (CD) and N-(3, 4-dichlorophenylcarbamoyl)-N-methyl β-alanine methyl ester (MCMD) bear a marked structural resemblance to diuron, respectively. Consequently, influence of CD and MCMD on photochemical electron transport in chloroplasts isolated from leaves of wheat, large crabgrass, spinach and rough pigweed was examined, together with that of diuron, as a reference chemical. It is interesting to find out whether inhibitory activities of CD and MCMD against the Hill reaction and cyclic photophosphorylation are altered by the addition of the antidote OM.
(1) Herbicides CD and MCMD seemed to have almost no inhibitory activity on photochemical reaction system, showing an approximate median inhibition at 10-4M. OM was completely inactive below 2×10-3M.
(2) Inhibitory activity of MCMD was higher than that of CD. I50 (half inhibition M) values of CD and MCMD on the Hill reaction by the above described broadleaf chloroplasts were higher than those by the above described monocotyledon chloroplasts. The results were not compatible with herbicidal activities tested by foliar application.
(3) Inhibitory activities of CD and MCMD against the above mentioned photochemical reactions were not reduced by the addition of OM. On the contrary, those inhibitory activities were strengthened by the addition of OM.
