Morphology and Postharvest Performance of Geogenanthus undatus C. Koch & Linden ‘Inca’ after Application of Ancymidol or Flurprimidol

Abstract

Excessive internode elongation and leaf senescence are common problems with foliage plants transferred to interiorscapes. The authors’ objective was to determine whether plant growth regulators applied late in the production cycle could control growth during production and improve interiorscape performance. In addition, the authors wanted to quantify the effect of irradiance on growth and morphology during the production phase and in the interiorscape. Geogenanthus undatus C. Koch & Linden ‘Inca’ plants were grown under one of two photosynthetic photon fluxes (PPF; 50 or 130 μmol·m−2·s−1), and were treated with either α−(methylethyl)-α-[4-(trifluoromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol) or α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol) during the week 12 production, at 0.5, 1.0, or 1.5 mg/pot of active ingredient. The high PPF resulted in significantly higher leaf, stem, root, and total dry weight, and leaf area, but lower leaf area ratio (leaf area divided by total plant dry weight) compared with the low PPF. After production, plants were placed in a simulated interior environment for 4 months under a PPF of 15 μmol·m−2·s−1 and a photoperiod of 12 hours/day. Production PPF did not affect most growth parameters after 4 months in the interior environment, except for the root-to-shoot ratio. Under low-production PPF, root-to-shoot ratios were lower than under high-production PPF. For both growth regulators, the height and growth indexes were lower than for control plants, but flurprimidol offered greater control than ancymidol. Flurprimidol-treated plants had lower root dry weight and root-to-shoot ratios compared with ancymidol-treated and control plants. Applications of ancymidol or flurprimidol administered to G. undatus C. Koch & Linden ‘Inca’ late during the production cycle resulted in significant growth control and, therefore, superior plant performance throughout the postharvest period.