Effects of Ancymidol (a Growth Retardant) and Triarimol (a Fungicide) on the Growth, Sterols, and Gibberellins of Phaseolus vulgaris (L.)

The effect of the two substituted pyrimidines, ancymidol (a growth retardant) and triarimol (a fungicide) on Phaseolus vulgaris was studied. Both compounds retarded shoot and root elongation as well as increases in fresh weight. Both compounds caused production of ethylene-like responses when given in high dosages or when applied shortly after germination. As growth retardation was shown to occur in the absence of net increase in sterol levels, neither ancymidol nor triarimol apparently retards growth by inhibiting sterol synthesis.Both ancymidol and triarimol treatment drastically reduced the amount of extractable gibberellin-like activity in beans. Ancymidol also either induced or enhanced the production of a compound which gave a negative response in the bioassay plant Oryza sativa var. Tan-ginbozu. The addition of gibberellin completely relieved the dwarfing effects of both ancymidol and triarimol in dark-grown beans. It is concluded that ancymidol and triarimol affect a gibberellin-induced growth response, probably by inhibiting gibberellin biosynthesis.