Abstract
Understanding the physiological basis of ethylene-mediated reproductive development in ornamental Bromeliaceae species is essential for developing reliable cultivation protocols in climatically variable regions. This study comparatively evaluated the dose- and temperature-dependent efficacy of ethephon, ethylene, and acetylene as floral induction agents in two commercially important taxa, Guzmania ‘Ostara’ and Tillandsia cyanea, under controlled environmental conditions. The experiment was designed as a randomized complete block design with two temperature regimes (22°C and 35°C) and seven hormone application combinations. Flowering success, developmental synchronization, flowering time, and morphological parameters were analyzed using ANOVA, Tukey HSD multiple comparison test, and chi-square independence analysis (p < 0.05). At 22°C, ethephon applications at all tested concentrations (60, 80, and 150 mL/100 L) induced consistent, uniform flowering. The highest flowering success in T. cyanea was recorded at 80 mL/100 L (91.0 ± 2.65%; 44 ± 1.0 days to flowering). In contrast, aqueous ethylene and acetylene solutions produced irregular flowering responses in T. cyanea, while inducing greater plant height in Guzmania ‘Ostara’ compared with ethephon treatments (55.0-56.5 cm versus 36.0-45.0 cm; ANOVA: F = 453.12, p < 0.001). Under elevated temperature stress (35°C), ethephon retained considerable efficacy in T. cyanea (76.0 ± 3.00%; 49 ± 1.0 days to flowering), whereas Guzmania ‘Ostara’ showed severe reproductive suppression, with only limited and irregular flowering. Applications of ethylene and acetylene failed to elicit consistent flowering responses under high-temperature conditions. These findings indicate that flowering induction in Bromeliaceae is strongly influenced by hormone source, dose, temperature, and species-specific physiological responsiveness. Ethephon was identified as the most reliable floral induction agent under variable production conditions, while acetylene may serve as a practical alternative to ethylene under favorable temperatures. Overall, the results provide valuable guidance for improving flowering synchronization and developing species-specific, climate-adapted cultivation strategies in commercial bromeliad production.
| Keywords: | Bromeliaceae Ethephon Ethylene Flowering Induction Temperature Guzmania Tillandsia |