GIBBERELLINS PLAY A ROLE IN THE INTERACTION BETWEEN IMIDAZOLE FUNGICIDES AND CYTOKININS IN ARACEAE

Imidazole fungicides such as imazalil, prochloraz, and triflumizole an d the triazole growth retardant paclobutrazol promote the shoot-induci ng effect of exogenous cytokinins in Araceae, such as Spathiphyllum fl oribundum Schott and Anthurium andreanum Schott. The mechanism of thei r action could partially be based on the inhibition of gibberellic aci d (GA) biosynthesis, because administration of GA(3) inhibits the phen omenon completely in S. floribundum, Not only is the suppression of GA biosynthesis involved, but also the metabolism of endogenous cytokini ns is significantly altered. Although the balance between isopentenyla denine, zeatin, dihydrozeatin, and their derivatives was shifted to di stinguished directions by administration of BA and/or imazalil and/or GA(3), no correlation between these changes in metabolic pathways and the number of shoots could be found. The metabolism of BA was not sign ificantly altered by adding imazalil to the micropropagation medium of S. floribundum.