Masters Theses

Date of Award

12-1997

Degree Type

Thesis

Degree Name

Master of Science

Major

Landscape Architecture

Major Professor

Terri W. Starman

Committee Members

Robert Auge, James E. Faust, Joanne Logan

Abstract

There has been a recent trend in the floriculture industry towards producing specialty crops to supply consumers with something new and different. Cultural information is needed to aid growers in producing newly introduced species. Photoperiodic responses were determined for: Abutilon hybrid Hort. 'Apricot', Argeranthemum frutesecens 'Sugar Baby', Centradenia grandifolia (Schlechtend.) Endl., Diascia hybrid Link & Otto. 'Ruby Fields', Duranta repens L. 'Blue', Evolvulus nuttallianus Roem & Schult. 'Blue Daze', Heliotropium arborescens L. 'Fragrant Delight', Lotus berthelotii Masf. Parrot’s Beak', Lysimachia nummularia L. 'Aurea Creeping Golden', Nemesia fruticans Venten., Nemesia fruticans 'Innocence', Orthosiphon stamineus L. 'Lavender', Pandorea jasminoides (Lindl.) K. Schum. 'Swaggy White, Portulaca hybrid L. 'Apricot', Rhodanthe anthemoides (Sieber) DC. 'Milkyway', Rosmarinus officinalis L. 'Prostratus', Scaevola aemula 'Fancy Fan Falls', Sutera cordata 'Snowflake' and 'Mauve Mist', Tabernaemontana coronaria (Jacq.) Willd. 'Double', Tibouchina semidecandra Hort. 'Spanish Shaw', Verbena hybrid L. 'Tapien Pink', Verbena peruviana (L.) Britt. 'Trailing Katie', and Tasmanian violet (Viola hederacea Labill.) 'Tasmanian'. Each species was grown at 8-, 10- 12-, 14-, and 16 -h photoperiods. Photoperiods were provided by 8 h of sunlight, then pulling blackcloth and providing daylength extension with incandescent bulbs. Diascia, Nemesia and Nemesia 'Innocence', Sutera 'Mauve Mist' and 'Snowflake', Tibouchina, and Tasmanian violet were day neutral with regard to flowering and vegetative parameters. Evolvulus, heliotrope, and Orthosiphon were quantitative short day plants. Argeranthemum, Portulaca and Scaevola increased in flower number as photoperiod increased from 8- to 16- h, although time to flower was not affected. Duranta, Verbena ‘Tapien Pink' and ‘Trailing Katie' were facultative long day plants with regard to flowering. Days to visible bud and first open flower decreased as photoperiod increased. Lotus, Lysimachia, and Rhodanthe did not flower during the experiments but did have increased vegetative growth as photoperiod increased. Centradenia, Pandorea, rosemary, and Tabernaemontana did not flower during the experiment and the vegetative growth was not affected by photoperiod. The effect of increasing temperatures on the duration of flower development was determined for Ageranthemum frutescens 'Butterfly' and 'Sugar Baby', Brachycome hybrid Cass. 'Ultra', and bacopa (Sutera cordata Roth.) 'Snowflake'. Marketable plants i.e., plants flowering and with foliage covering the container, were placed in a phytotron with temperature set points of 18- 23-, 28-, and 33 °C for two week intervals, starting at 18 °C. Data collected once per week included flower bud and flower number. Argeranthemum 'Butterfly' increased in flower number during 23- and 28 °C, however flower senescence increased during the 28 °C temperature. Argeranthemum ‘Sugar Baby' increased in flower number at the 18 and 23 °C temperature. Similar to 'Butterfly', flower senescence Increased in a 28 °C environment. Sutera 'Snowflake' had greatest flower and bud numbers at 23 °C. Brachycome 'Ultra' had the greatest flower and bud number in 28 °C, however flowers were observed to be smaller in size.

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