Thursday July 31, 2025 12:00pm - 12:15pm CDT
Greenhouse substrates are soilless mixes formulated by blending organic and inorganic components at varying proportions. Substrate properties are known to influence the efficacy of plant growth regulators applied as a substrate drench. Ethephon is a plant growth regulator used in floriculture production to control stem elongation, increase lateral branching, and manipulate flowering. Ethephon substrate drenches have been shown to control growth in annual bedding plants and herbaceous perennials; however, there is a lack of research examining how substrate composition influences the efficacy of ethephon substrate drenches. Therefore, the objective of this research was to evaluate ethephon drench efficacy in peat-based substrates amended with perlite, aged pine bark, or wood fiber. Lantana (Lantana camara L. ‘BandoleroTM Pink’ and ‘New Gold’) were transplanted into 15.2-cm containers filled with one of six peat-based substrates amended (by vol.) with 20% or 40% perlite, aged pine bark, or wood fiber. After 10 d, eight single-plant replicates received a drench of 150 mL aliquots of solution containing 0, 25, 50, 75, 100, or 200 mg·L–1 ethephon. Plants were grown in a glass-glazed greenhouse for 5 weeks after drench before growth data, including plant height, plant diameter, shoot dry weight (SDW), and root dry weight (RDW) were determined. Increasing concentrations of ethephon decreased plant height, plant diameter, SDW, and RDW of both cultivars of lantana. Substrate components and formulation had varied effects on plant growth. For example, in Expt. 1, plant height was unaffected by formulation but the component × concentration interaction was significant. When substrates were formulated with perlite, aged pine bark, or wood fiber plants were 23% (3.9 cm), 13% (2.0 cm), and 18% (3.1 cm) shorter, respectively, as concentrations increased from 0 to 200 mg·L–1 ethephon, compared to untreated plants. In Expt. 2, neither component or formulation significantly influenced plant height, and when drenched with 200 mg·L–1 ethephon plant diameter was 42% (15.8 cm) less than untreated plants. In Expt. 1, SDW was not influenced by formulation but the component × concentration interaction was significant. For instance, compared to untreated plants, SDW of plants grown in substrates containing perlite, aged pine bark, or wood fiber were 42% (3.8 g), 23% (1.7 g), and 35% (2.7 g) smaller, respectively, as concentrations increased from 0 to 200 mg·L–1 ethephon. Overall, ethephon substrate drench efficacy was not reduced by the incorporation of perlite, pine bark, or wood fiber in peat-based substrates.
Speakers WR
The Ohio State University
GO
The Ohio State University
Thursday July 31, 2025 12:00pm - 12:15pm
CDT
Foster 2
