Effects of a New Plant Growth Retardant (E)-1-(4-Chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (S-3307) on the Growth and Gibberellin Content of Rice Plants

The properties and mode of action of a new plant growth retardant,(E)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol(S-3307), were investigated. When a dipping method was used,S-3307 at 2.2 ? 10^-7 M (0.064 ppm) retarded the growth of riceplants by 50% of the value found for the control. The retardationof growth was removed by a gibberellin application (8.7?10^-5M). S-3307 had nearly no effect on the shoot elongation inducedby gibberellin. The amounts of gibberellin-like substances inrice shoots were decreased by S-3307 treatment in proportionto the degree of growth retardation. This observation was confirmedwith GA₁ and GA₁₉, the main gibberellins in the rice plant.Our results indicate that S-3307 inhibits gibberellin biosynthesisin rice plants. (Received November 7, 1983; Accepted March 21, 1984)