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The State Botanical Garden of Georgia serves as an important academic resource for the University of Georgia by supporting interdisciplinary learning experiences in fields including botany, horticulture, environmental design, ecology, anthropology, geography, instructional technology, science education, entomology, forestry, and art. Field trips, independent study, internships, work-study and other botanical garden experiences strengthen and support the university's teaching, research and public service/outreach missions.
Dense-flowered loosestrife is a quantitative long-day (LD) plant. Plants given a LD photoperiod (16 hours) flowered 21 and 34 days earlier than plants given 12- and 8-hour photoperiods, respectively. Plants under LDs produced significantly more flowers than those under 8- and 12-hour photoperiods. Only 1 week of LD was needed for 100% flowering; however, optimum flower count and size were produced with 3 weeks of LD. Plant dry weight did not differ significantly among treatments; however, LDs produced fewer but larger leaves, particularly those subtending the inflorescence. Total plant growth increased as temperature increased, but lower temperature (10C) decreased flower initiation and prevented flower development. High temperature (26C) reduced the persistence of open flowers. The optimum temperature for dense-flowered loosestrife growth was ≈20C. Flowering was accelerated and dry weight production increased as irradiance levels increased from 100 to 300 μmol·m–2·s–1.
Arabis sturii Mottet (Brassicaceae) has potential as a new crop for American nurseries and may be used as a perennial pot plant. Cold treatment was required for flowering of Arabis sturii and a 6-week cold treatment resulted in the greatest number of racemes and flowers per plant. Increasing or decreasing length of cold treatment resulted in less flowers per plant. Plant height increased as duration of cold treatment increased. Photoperiod had a significant effect on flowering and growth only after plants received 3 weeks or more cold treatment. All plants given a 16-h photoperiod flowered, while only 50% and 80% flowered under an 8- or 12-h photoperiod, respectively. A 16-h photoperiod shortened the time to production of flower buds and anthesis and the greatest difference occurred after the 9-week cold treatment. At the 6-week cold treatment, number of flowers per plant different significantly between long (145 flowers) and short day (59). The effect of photoperiod on number of flowers per plant became less as cold treatment increased or decreased. Although photoperiod did not induce flower initiation, it had a tremendous effect on flower development. Many more flowers were produced and plants were taller as photoperiod increased. No significant difference was found in plant dry weight.
Platycodon grandiflorus (Jacq.) A. DC. `Sentimental Blue' can be used as a pot plant and garden perennial. Plants can be grown year-round in a greenhouse as cutting flowers if supplemental heat is provided in the winter. Sowing time did not affect plant growth and flowering. Seeds took 10 to 20 days to germinate at 20–25 °C day/15–20 °C night temperatures. As the day/night temperature decreased, time to germination increased and germination rate decreased. Temperature also influenced shoot proliferation and number of basal branches increased as temperature decreased. Plants reached reproductive growth about 20 days after transplanting and took another 20 days to reach full bloom. Open flowers lasted 3–7 days. Cold treatment was not necessary for flowering, but plants were forced into dormancy when provided with 5 °C for 4 or more weeks. Plants began to emerge 2 to 3 months later and two growth forms, “rosette” and “dwarf”, occurred in the second growth cycle. The dwarf form produced one or two stems with six to eight clustered flowers per stem while the rosette form produced an average of 10 stems with one or two flower per stem. For the “rosette” form, each stem could be divided as a new plant.
Achillea millefolium `Summer Pastels' is a qualitative long-day plant with a critical photoperiod between 12 and 16 hours at 18C. Plants grown under a 16-hour photoperiod flowered after 27 days, while those under 8 hours remained vegetative. Shoot dry weight was not affected by photoperiod. Low temperature (10C) delayed the time of flower bud formation and anthesis by ≈20 days. Low irradiance (100 μmol·m–2·s–1) delayed flowering and resulted in lower shoot dry weight, while moderate shading (200 μmol·m–2·s–1) did not significantly affect flowering time and growth compared with high irradiance levels (300 μmol·m–2·s–1).