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Fuchsia × hybrids `Dollar Princess' plants were grown under 35 day/night temperature (DT/NT) environments ranging from 10 to 30C over 2 years. Plants were grown under short days (SD) (9-hour 15-minute photoperiod) or long days (LD) (9-hour 15-minute photoperiod plus a 4-hour night interruption) within each environment. The influence of temperature on Fuchsia stem elongation and leaf expansion was best described by the relationship or difference (DIF) between DT and NT (DT - NT) rather than actual DT and NT between 10 and 25C. Both internode length and leaf area increased linearly as DIF increased from - 15 to + 15C with DT and NT between 10 and 25C. Internode length increased 0.129 and 0.071 cm/1C increase in DIF for LD- and SD-grown plants, respectively. Individual leaf area increased 0.52 and 0.40 cm2/1C increase in DIF for LD- and SD-grown plants, respectively. DT or NT above 24C reduced stem elongation and leaf expansion, regardless of DIF. The response of stem elongation and leaf expansion to DIF was greater on a percent basis when plants were grown under SD and LD, respectively. On an absolute basis, both internode length and leaf area were greater on LD-grown plants. Branching increased as average daily temperature decreased from 25 to 12C. Photoperiod did not affect branching.

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Abbreviations: KT, killing temperature; LD, long photoperiod; ND, natural photoperiod; SD, short photoperiod. 1 Present address: Plant Molecular Biology Center, Montgomery Hall, Northern Illinois Univ., Dekalb, IL 60115-2861. Science Journal Series

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Abstract

Peppermint (Mentha piperita L.) was grown under growth room conditions with two photoperiodic treatments, short day and long day. Each treatment received a total of 13 hours light per 24 hour cycle, either continuously (13H) or as an interrupted night treatment (131) with 1 hour of light in the middle of the dark period. In addition to the previously reported changes in dry matter yield of herb, oil yield, growth habit and flowering, the photoperiodic treatments strongly influenced the proportions of several individual monoterpenes in peppermint. The long day treatment resulted in reduced levels of menthofuran, pulegone, menthyl acetate and limonene as well as increased levels of menthone, menthol, neo menthol acetate (+ unknown), trans-sabenine hydrate, cineole and β pinene + sabenine.

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Abbreviation∼ CHO, carbohydrate; DW, dry weight PE, photoperiod extension; Pn, photosynthesis; PPF, photosynthetic photon flux; SLW, specific leaf weight. 1 Currently, Assistant Professor, Dept. of Horticulture, Forestry, Landscape, and Parks, South

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Abbreviations: LD, long days: LIP, limited inductive photoperiod; SD, short days; SLD, short-long day. 1 `Former Graduate Student. 2 Associate Professor. The cost of publishing this paper was defrayed in part by the payment of page charges. Under

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the induction of flowering in arabidopsis by long-day photoperiods in a mechanism that involves integration of light signals and the circadian clock of the plant ( Suárez-Lopez et al., 2001 ; Valverde et al., 2004 ; Yanovsky and Kay, 2002 ). In

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Abstract

More rhizomes were initiated by plants of ‘Astrid’ chrysanthemum grown in short day and cool air temperature than in long day and warm air. Rhizome development was greatest, shoot growth was enhanced, and root length and dry weight increased with warm compared to cool soil temperature. Rhizomes grown at a cool soil temperature either in long or short days had the least cellular injury after exposure to –8°C.

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the adaptive phenology of a species ( Moyses et al., 2018 ). During common bean domestication and dissemination from its centers of domestication, selection for photoperiod insensitivity allowed common bean to spread to higher latitudes ( Gepts and

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Most ornamental crops can be classified as long-day, short-day, or day-neutral plants based on their flowering responses to the photoperiod (or the skotoperiod). Chrysanthemum ( Chrysanthemum × morifolium ) is a common ornamental crop with an

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The influence of photoperiod and temperature on the seasonal (fall to winter) cold acclimation and accumulation of a 25 kDa dehydrin in Rhododendron `Chionoides' was studied by exposing two groups of plants each in the greenhouse or outdoors to either a natural photoperiod (or short days) or an extended photoperiod (or long days) regime. Results suggest that the shortening daylength alone is sufficient to trigger both the first stage of cold acclimation and concomitant 25 kDa dehydrin induction. Exposure of the plants to natural photoperiod and temperatures induced the greatest cold hardiness and 25 kDa accumulation, while exposure to extended photoperiods (long days) and warmer temperatures (in the greenhouse) failed to induce any significant freezing tolerance in leaves. Whereas short days trigger the cold acclimation process initially, low inductive temperatures can eventually replace the photoperiod stimulus. Seasonal accumulation of 25 kDa dehydrin, on the other hand, appears to be predominantly effected by short photoperiods. Data indicated that the leaf water content of outdoor plants maintained under natural photoperiod was lower than that of plants grown under extended photoperiod. This was also true for the greenhouse plants at the first (September) and the last (January) sampling. It is hypothesized that early 25 kDa dehydrin accumulation may be due to short-day-induced cellular dehydration. Accumulation of two other dehydrins of 26 kDa and 32 kDa molecular masses does not appear to be associated with short day (SD)-induced first stage of cold acclimation. Results show that their accumulation may be regulated by low, subfreezing temperatures and may be associated with the second and/or third stage of cold acclimation of `Chionoides' rhododendron leaves.

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