Effects of Paclobutrazol Application Methods and Dosages on the Growth, Morphological Characteristics, and Color Quality of Silene compacta Fisch.
Selma Kösa*
Department of Landscape Architecture, Faculty of Architecture, Akdeniz University, Antalya, Turkey
* Corresponding Author: Selma Kösa. Email: 
(This article belongs to the Special Issue: Regulators of Plant Growth and Environmental Stress Adaptation)
Phyton-International Journal of Experimental Botany https://doi.org/10.32604/phyton.2026.079055
Received 13 January 2026; Accepted 05 March 2026; Published online 19 March 2026
Abstract
This study was conducted to determine the effects of paclobutrazol (PBZ) application methods and dosages on the growth, leaf, flower, and color characteristics of
Silene compacta Fisch., a natural species with high potential for use as a seasonal bedding and potted ornamental plant in landscape design. The experiment was carried out under greenhouse conditions, where potted plants received a single PBZ application during the vegetative stage. The study was arranged in a completely randomized design with a 2 × 3 factorial structure. PBZ was applied either as a foliar spray or as a soil drench at doses of 0, 1.250, and 2.500 mg a.i. per plant. Measurements were taken at the 90% flowering stage. The study revealed that increasing PBZ dosages led to a significant delay (10–15 days) in flowering time. Increasing PBZ dosages significantly suppressed plant height, internode length, inflorescence and leaf traits; conversely, stem diameter and fresh stem (86%) and root (132%) weights increased markedly. While application methods exerted contrasting effects on leaf number and thickness, the suppressive effect of the soil drench method on growth was found to be more dominant than that of the foliar spray. Specifically, high-dose soil applications restricted plant height by 80% (5.0–6.0 cm) to create a compact form, whereas foliar-sprayed plants resulted in a growth trend closer to the control (17.5–18.5 cm). In terms of color quality, PBZ did not exert a negative effect on the primary color tones. Specifically, the soil drench application at a dosage of 2.500 mg a.i./plant increased leaf lightness and saturation; meanwhile, the foliar spray at a dosage of 2.500 mg a.i./plant significantly enhanced flower color saturation (chroma) compared to the control group. These results establish an important theoretical and practical foundation for the use of
S. compacta in urban landscape design and potted interior/exterior arrangements with a compact form and high visual quality.
Keywords
Silene compacta; growth retardants; morphological development; colorimetric analysis; ornamental quality
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