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Rhizomes of Curcuma alismatifolia `Chiang Mai Pink' and tissue cultured plants of C. cordata, C. petiolata `Emperor', C. thorelii, Kaempferia sp. `Grande', Siphonichilus decora and S. kirkii were grown in a greenhouse under 8-, 12-, 16-, and 20-hour photoperiods. All plants grown under the 8-hour photoperiod became dormant over a 15 week time period. After 90 days, most ginger species grown under the 16- and 20-hour photoperiods were taller than those grown under 8 and 12 hours. A larger number of unfolded leaves was indicated for all ginger species grown under 16- and 20-hour photoperiods compared to those grown under 8- and 12-hour photoperiods except for C. thorelli. The percentage of unfolded leaves as determined by quartile indicated similar results. The number of underground rhizomes of C. alismatifolia, C. cordata, and C. petiolata increased when plants were grown at 16 and 20-hour photoperiods. The number of tuberous-roots (t-roots) increased as photoperiod decreased below 16 hours for C. alismatifolia, C. cordata, C. petiolata, Kaempferia sp. and S. kirkii. Siphonichilus decora produced no t-roots while C. thorelii produced the most t-roots at 16 hours. Vegetative growth of gingers grown in this study, except for C. thorelii, was maintained and increased at photoperiods of 16 and 20 hours.

Photoperiods of 8 and 12 hours induced dormancy and t-root production of most of these gingers.

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factors influencing floral initiation and development were studied. The ability to manipulate flowering is a first step in developing commercial seed production protocols. Temperature and photoperiod are two of the most important environmental factors in

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photoperiod, can be controlled in an indoor system. Thus, plug production using artificial lighting with an optimal photoperiod would produce high-quality strawberry plugs because flowering could be controlled by changing the photoperiod during transplant

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fall, shorter photoperiods and decreases in temperature start the process for the plant to enter into endodormancy. Whereas several woody plants respond to both low temperature and photoperiod to start dormancy, it has been demonstrated that grape are

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developed for use as cut flowers to long or short photoperiods in experiments over 5 years, and classified their responses. The objectives of the current work were to test cut-flower cultivars of sunflower for the effect of daylength in the seedling stage on

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In 1996 and 1997, eight cultivars of cold-treated field-grown Astilbe were grown in a 20 °C green-house with short days (SDs = 9-h natural days) or long days (LDs = 9-h natural days with night interruption with incandescent lamps from 2200 to 0200 hr) to determine how photoperiod influences flowering. Cultivars studied were Astilbe × arendsii Arends `Bridal Veil', `Cattleya', `Fanal', and `Spinell'; A. chinensis Franch. `Superba'; A. japonica A. Gray `Deutschland' and `Peach Blossom'; and A. thunbergii Miq. `Ostrich Plume'. Flowering percentage was highest (≥90%) for `Cattleya', `Deutschland', `Fanal', `Ostrich Plume', and `Peach Blossom', regardless of photoperiod. Photoperiod did not affect the time to visible inflorescence or flower number for any cultivar studied. The time from visible inflorescence to first flower took 27 to 36 days, irrespective of photoperiod. Time to flower varied by cultivar; `Deutschland' was the earliest to flower (31 to 41 days) and `Superba' was the last to flower (51 to 70 days). `Fanal' and `Ostrich Plume' flowered slightly but significantly faster (by 1 to 6 days) under LDs than SDs. For five cultivars, the inflorescence was taller under LDs than SDs. All cultivars reached visible inflorescence and flower significantly faster (by 1 to 15 days) in 1997 than in 1996.

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, light intensity, pruning, and photoperiod ( Hackett and Sachs, 1985 ; Norcini et al., 1994 ). ‘Afterglow’ bougainvillea ( Bougainvillea × buttiana ) plants grown under SDs (8 h) had visible inflorescences within 30 d, with 8 to 10 inflorescences per

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flowers in response to shortening photoperiods. Hemp development occurs over a continuum that may be classified into juvenile (vegetative), photoperiod inductive (vegetative and flowering), and harvest maturity (anthesis) stages ( Amaducci et al. 2008a

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The interaction among temperature, photoperiod, and irradiance on survival of Chamaecereus silvestrii (yellow sport) flat-grafted onto Hylocereus trigonus Haw. rootstock was studied in an effort to understand the basis for elevated scion necrosis during winter. Plants were placed in glasshouses maintained at 12, 16, 20, or 24 °C under either daylight (moles per day), 66% daylight or daylight + 100 μmol·s−1·m−2 irradiance levels. Plants were grown with an 8-hour (short day) or 8-hour + 4-hour night interruption (long day) photoperiod. Cactus scion necrosis increased under short days and a growing temperature of 12 °C and was nearly eliminated by long-day conditions and a growing temperature of 16 °C. Irradiance did not affect scion necrosis. Plant quality rating was highest when plants were grown under long-day conditions at 16 °C.

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Rooting of cuttings from three cultivars of Euphorbia pulcherrima Willd. was evaluated after regulating the photoperiod during the stock plant stage. One group of stock plants was exposed to a night break (4 hours) and another group was exposed to natural daylength during September. Cuttings harvested in late September from `Freedom Red' and `Monet' stock plants grown under the 4-hour night break rooted more rapidly and had greater root mass than `Freedom Red' and `Monet' grown under natural daylength, whereas rooting of cuttings from `V-17 Angelika Marble' was not influenced by the photoperiods tested. Using a night break to prevent flower initiation of stock plants produced a higher-quality cutting when propagation took place after the critical daylength for flowering had passed.

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