Differential Effects of Herbicides upon Trypsin-Treated Chloroplasts

Abstract

Abstract With trypsin-treated spinach chloroplasts and the assay system H2O→ FeCy, photosynthetic electron transport inhibitors could be subdivided into four groups according to their different inhibitory behaviour under the conditions used. 1. Inhibition exerted by ureas, triazines, triazinones and pyridazinones was reversed to 50 - 60% as against the untreated control. 2. Inhibition by dibromothymoquinone, trifluralin or the 2,4-dinitrophenylether of 2-iodo-4-nitrothymol was almost completely reversed. 3. Inhibition caused by higher concentrations of nitrofen or the analog RH 2512 could only be reversed to a small extent. 4. Phenol herbicides showed increased inhibitory activity during short-term assays.