Growth of Four Tropical Foliage Species Treated with Paclobutrazol or Uniconazole

Abstract

Uniconazole and paclobutrazol were tested for their effects on greenhouse production of four foliage species. Soil drenches of uniconazole retarded shoot and petiole elongation of Brassaia actinophylla Endl. Paclobutrazol reduced shoot elongation, but required higher doses than uniconazole and did not reduce petiole growth. Foliar sprays with either retardant at 12.5 mg·liter-1 resulted in short stems on lateral shoots of Codiaeum variegatum (L.) Blume `Karen' after pinching, but soil drenches at low rates were less effective. Soil drenches of uniconazole or paclobutrazol were equally effective in reducing stem growth of Syngonium podophyllum Schott `White Butterfly' and increasing leaf width, but had no effect on the rate of leaf production or blade length. Both retardants induced short petioles in this species. Severe growth reduction occured on Plectranthus australis R. Br. even at the lowest rates of uniconazole and paclobutrazol (0.025 and 0.20 mg/pot, respectively) as soil drenches. Production of lateral shoots was inhibited for P. australis by both retardants. Chemical names used: (E)-1-(p-chlorophenyl)-4,4-dimethy1-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (uniconazole); (2RS,3RS)-1-(4-chlorophenyl)-2-(1,1-dimethylethyl)-(H-1,2,4-triazol-l-Yl-)Dentan-3-ol (paclobutrazol).