Aspects biochimiques des herbicides à base de triazines

Summary The triazine herbicides are potent inhibitors of theHill reaction, resembling the phenylureas, acylanilides and carbamates. The inhibition of the photosynthesis by the triazines is the most obvious explanation for their mode of action in plant metabolism. Besides this there are also effects on light independent reactions where the effective concentrations are higher than those inhibiting the photosynthesis. Particularly, a positive influence of the triazines on the uptake of the nutrients by the roots was noted. Changes in the nitrogen metabolism of the plants, due to increased uptake of nitrate from the medium, result in a higher content of organic nitrogen in the plants.Several enzyme systems in plants and in micro-organisms are influenced by the triazine herbicides. Until now, the mechanism of action has not been elucidated.Concerning the phenomenon of the selectivity of the triazine herbicides, several factors may be responsible. The different abilities of the plant species to metabolize the herbicide and to translocate it to the active centres in the cells are significant from the biochemical point of view.

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Une partie de ce travail a été présentée lors de la 463^e séance de la Biochemical Society, Aberystwyth, septembre 1966.P. W. Müller, Biochem. J.101, 1P. (1966).Nous tenons à exprimer nos remerciements àR. Truan qui a bien voulu se charger de la version française ainsi qu'àG. Dupuis pour sa participation à la mise au point du manuscrit.