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  • Author or Editor: Kelly P. Lewis x
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Three cultivars of New Guinea impatiens (Impatiens hawkeri) and two cultivars of double impatiens (I. walleriana) were grown in greenhouses maintained at 15, 20, and 25 °C. Bud diameter was measured twice weekly on five plants per cultivar from the time of visible bud to open flower. The experiment was repeated twice. For New Guinea impatiens, the time from visible bud (1-mm diameter) to open flower was 31, 43, and 72 days at 25, 20 and 15 °C, respectively. Flower bud diameter increased linearly as the bud expanded from 1 to 9 mm. For double impatiens, the time from visible bud (1-mm diameter) to open flower was 25, 30, and 58 days at 25, 20 and 15 °C, respectively. Flower bud diameter increased at an increasing rate (curvilinear response) as the bud expanded from 1 to 8 mm. These models are currently in commercial use to aid greenhouse growers in accurately timing crops for specific market dates.

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Poinsettia (Euphorbia pulcherrima Willd. Ex Klotzch) `Freedom Red' (FR), `Success Red' (SR), and `Winter Rose Dark Red' (WRDR) and pansy (Viola wittrockiana Gams.) `Colossus Yellow Blotch' (CYB), `Delta Pure Yellow' (DPY), and `Majestic Giants Purple' (MGP) were treated with 14 different tank mix combinations of daminozide and chlormequat ranging from 0 to 4500 mg·L-1 daminozide and 0 to 1500 mg·L-1 chlormequat. The tank mix treatments reduced stem elongation for all three poinsettia cultivars. Total bract area of FR and canopy bract diameter of WRDR decreased linearly as daminozide or chlormequat concentration increased, while bract area of SR was affected by daminozide alone. Anthesis was not delayed by any of the plant growth regulator (PGR) applications. For pansies, growth responses to the PGR treatments varied with cultivar. CYB growth was affected by daminozide alone, DPY growth was affected by daminozide and/or chlormequat, while MGP growth was relatively insensitive to both PGRs. Time to flower of pansy was not affected by the PGR applications. Chemical names used: 2-chloroethyl N,N,N-trimethylammonium chloride (chlormequat chloride); butanedioic acid mono (2,2-dimethylhydrazide) (daminozide).

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The effects of storage temperature and shoot preparation of elephant ears (Colocasia antiquorum `Illustris') were examined to determine how to successfully store plants prior to greenhouse forcing. A series of experiments were conducted that provided storage temperatures of 4, 7, 10, 13, or 16 °C (39.2, 44.6, 50.0, 55.4, or 60.8 °F), and plants were placed into storage with the shoots uncut or cut to 3.0 cm (1.18 inches) above the surface of the growing medium. The storage duration ranged from 40 to 49 days. All plants stored at 4 or 7 °C died. Plant survival was 89% to 100% at 10 °C, while plant survival was 100% at 13 or 16 °C. Shoot emergence and plant growth was faster following storage at 13 and 16 °C, than storage at 10 °C. Storage at 16 °C resulted in leaf growth occurring during storage, which was undesirable. Removing shoots prior to storage had no effect on plant survival and performance during forcing. A fungicide drench with iprodione immediately prior to storage did not improve plant survival. This study suggests that 13 °C is near the base temperature for leaf development of elephant ears, thus the plants survive at this temperature with no growth occurring. Shoot removal prior to storage is recommended in order to optimize storage room space.

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