Masters Theses
Date of Award
5-2001
Degree Type
Thesis
Degree Name
Master of Science
Major Professor
Terri W. Starman
Committee Members
Robert Auge, Mary Albrecht
Abstract
The recent trend of the floriculture industry is a move towards vegetative annuals. This trend has brought about the introduction of many new and unique species to the market. Cultural information is needed for these new crops in order to grow them effectively and efficiently. The developmental and reproductive responses of Argyranthemum frutescens Webb ex Schultz-Bip 'Sugar Baby', Calibrachoa 'Million Bells Cherry Pink', Orthosiphon stamineus L. 'Lavender', and Scaevola aemula R. BR. 'New Wonder' were examined in various experiments with photoperiod, limited inductive photoperiod, supplemental light and plant growth regulators.
Argyranthemum frutescens 'Sugar Baby' was found to be a facultative long-day plant. In a critical photoperiod experiment using incandescent lighting, plant height and axillary branch internode length increased while days to visible bud, first flower and flower development decreased as daylength increased from 8.5 to 16 h. High-intensity discharge supplemental lighting increased plant compactness and flower formation compared to ambient and ambient + 50% shade conditions. In a plant growth regulator experiment conducted under inductive photoperiod conditions, uniconazole spray at 20 mg-L-1 reduced plant height and pedicel length without reducing plant weight or flower number compared to untreated plants. In a comparison of methods of applying long days, high-intensity discharge daylength extension lighting kept plants compact and increased flower development without plant growth regulator treatment. Incandescent daylength extension and incandescent night interruption required the use of plant growth regulators to keep the plants compact. The use of short-day exposure following 20 inductive long days was effective in increasing plant compactness compared to continuous long-day lighting, without increasing time to first flower.
Calibrachoa 'Million Bells Cherry Pink' was found to be a facultative long-day plant. In a critical photoperiod experiment using incandescent lighting, plant width and branch length increased, while days to visible bud and first flower decreased as daylength increased from 8.5 to 16 h. High-intensity discharge supplemental lighting increased plant compactness and flower formation compared to ambient and ambient + 50% shade cloth conditions. In a plant growth regulator experiment conducted under inductive photoperiod conditions, uniconazole at 10 or 20, ancymidol at 132, and ethephon 500 or 1,000 mg-L-1 sprays, reduced internode length, making the plants more compact compared to untreated plants. In a comparison of methods of applying long day photoperiod, high-intensity discharge daylength extension lighting kept plants compact and increased weight and flower development without plant growth regulator treatment. When incandescent lighting was used, night interruption kept plants more compact than daylength extension. Plant growth regulator treatment was useful in reducing stem internode length without reducing rate of flower development when used with incandescent light treatments. The use of short-day exposure following 20 inductive long days was effective in increasing plant compactness compared to continuous long-day lighting, without increasing time to first flower.
Orthosiphon stamineus 'Lavender' was found to be a facultative short-day plant. Using incandescent lighting, plant height and time to visible bud, first flower and to develop increased from 8.5 to 16 h. High-intensity discharge supplemental lighting increased plant weight and flower formation compared to ambient and ambient +50% shade conditions. In a plant growth regulator experiment conducted under inductive photoperiod conditions, uniconazole spray at 20 mg-L-1 reduced plant height slightly without reducing reproductive development compared to untreated plants. Multiple applications, application technique, and tank mixtures were used for controlling the excessive stem elongation of O. stamineus 'Lavender'. A tank mix of daminozide at 5000 mg-L-1 and uniconazole at 20 mg-L-1 and uniconazole as a plug spray reduced plant height without increasing time to flower development.
Scaevola aemula 'New Wonder' stem length increased as photoperiod increased from 8.5 to 16 h in a critical photoperiod experiment using incandescent lighting. High-intensity discharge supplemental lighting increased plant compactness, flower formation and plant weight, while decreasing time to flower and to develop compared to ambient and ambient + 50% shade conditions. In a plant growth regulator experiment conducted under a long-day photoperiod, ancymidol and uniconazole treatments reduced stem length without increasing time to flower compared to untreated plants. Incandescent daylength extension, high-intensity discharge daylength extension lighting, and incandescent night interruption required the use of plant growth regulators to keep the plants compact although plant growth regulator treatment caused a delay in flowering and a reduction in plant weight. The use of short-day exposure following 15 inductive long days was effective in increasing plant compactness compared to continuous long-day lighting, without increasing time to first flower. Uniconazole drench at 0.25 mg-L-1 reduced plant width to acceptable levels under incandescent night interruption lighting.
Recommended Citation
Onken, Hope Kathryn, "Photoperiod, limited inductive photoperiod, supplemental lighting and plant growth regulators affect growth and development of four vegetatively-propagated annuals. " Master's Thesis, University of Tennessee, 2001.
https://trace.tennessee.edu/utk_gradthes/6591