INFLUENCE OF 1-AMINOBENZOTRIAZOLE (ABT) DERIVATIVES ON THE TOXICITY OF EPTC TO MONOCOTYLEDONOUS PLANTS

The effect of 1-aminobenzotriazole (ABT) and EPTC mixtures on plant growth was investigated in greenhouse experiments by presowing application in sand. The concentration of ABT for 50% shoot growth inhibition (I50) was about 1 mM in the monoctyledons investigated. Both subtoxic and toxic doses of ABT were antagonists of EPTC in maize (Zea mays L.). However, subtoxic doses of ABT were synergists of EPTC in wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and oat (Avena sativa L.). No correlation between ABT and EPTC sensitivity of monocotyledonous plants was found. Some of the C- and N-substituted ABT derivatives (e.g. N-methyl or N-benzyl-ABT) completely reversed the effect of toxic dose of EPTC in maize. These results are considered as indirect evidence for the hypothesis that oxidation by cytochrome P-450 enzymes is the biochemical target of EPTC and is involved in the mode of action of EPTC safeners.