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Author Arnott, J. T.
Title Growth Response of White and Englemann Spruce Seedlings to Extended Photoperiod Using Three Light Intensities Type Report
Year 1982 Publication Technical Report: Pacific Forestry Centre Abbreviated Journal
Volume (down) Issue Pages
Keywords Plants
Abstract Four seedlots of white spruce (Picea glauca (Moench) Voss) and three of Engelmann spruce (Picea engelmannii Parry), covering a range of 10 degrees of latitude and a range of altitudes, were sown in BC/ CFS Styroblocks and grown in a heated greenhouse and an unheated shadehouse, using incandescent light to provide a 19-h photoperiod. Four intensities of lighting were used: 0, 100,200, and 400 Ix. A second experiment with the same seedlots was conducted in growth rooms that were programmed to evaluate the effect of low night temperature on seedling shoot growth when the photoperiod was extended to 19 h, using a light intensity of 200 Ix.

Shoot length of white and Engelmann spruce seedlings grown under an extended daylength of 100 Ix were significantly taller than the control (0 Ix). There were no significant differences in shoot length or weight among the three intensities of light used to extend the photoperiod for all seedlots except the southern latitude-low elevation population of Engelmann spruce. The more northern populations of white spruce and the high altitude populations of Engelmann spruce did not require light intensities higher than 100 Ix to maintain apical growth. Low night temperature (7°C) did produce significantly smaller seedlings than the warm night (1SoC) regime. However, terminal resting buds of seedlings grown under the cool night regime did not form any sooner than on those seedlings grown under warm nights.
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Call Number IDA @ intern @ Serial 2372
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Author Lumsden, P. J., & Furuya, M.
Title Evidence for Two Actions of Light in the Photoperiodic Induction of Flowering in <italic>Pharbitis nil</italic> Type Journal Article
Year 1986 Publication Plant and Cell Physiology Abbreviated Journal
Volume (down) Issue Pages
Keywords Plants
Abstract Using one-day-old light-grown seedlings of Pharbitis nil we have shown that there are two distinct responses to light during the inductive dark period. The first is the classic night-break, which inhibits flowering at a specific stage of the circadian rhythm (assumed to be the basis of dark time measurement). The second action is to control the phase of this rhythm. The two responses were compared at the 6th and 8th hour of darkness. They differed in their dose responses, and by using very short exposures it was possible to achieve one response without the other. The response of the rhythm to light displayed characteristics of other circadian rhythms; the direction and sensitivity of the phase shift changed between the 6th and 8th h, the rhythm was reset by longer exposures to light, and with one critical light treatment at the appropriate phase, the rhythm was apparently abolished. These results offer direct support for an external coincidence model in the photoperiodic control of floral induction.
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ISSN 1471-9053 ISBN Medium
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Notes Approved no
Call Number IDA @ intern @ Serial 2375
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Author Hey, M.H.; DiBiase, E.; Roach, D.A.; Carr, D.E.; Haynes, K.J.
Title Interactions between artificial light at night, soil moisture, and plant density affect the growth of a perennial wildflower Type Journal Article
Year 2020 Publication Oecologia Abbreviated Journal Oecologia
Volume (down) in press Issue Pages
Keywords Plants; Community ecology; Light pollution; Milkweed; Precipitation; Sensory pollution
Abstract Artificial light at night (ALAN) has been shown to alter aspects of plant growth, but we are not aware of any studies that have examined whether the effects of ALAN on plants depend upon the backdrop of variation in other abiotic factors that plants encounter in field populations. We conducted a field experiment to investigate whether ALAN affects the growth and anti-herbivore defenses of common milkweed, Asclepias syriaca, and whether the effects of ALAN are influenced by plant density or soil moisture content. Artificial light at night, soil moisture, and plant density were manipulated according to a split-plot factorial design. Although increasing soil moisture by watering had no significant effects on latex exudation, attributes of plant growth generally responded positively to watering. The basal stem diameter (BSD) and height of plants were affected by ALAN x soil moisture interactions. For both of these variables, the positive effects of ALAN were greater for plants that were not watered than for plants that were. Basal stem diameter was also affected by an ALAN x plant density interaction, and the positive effect of ALAN on BSD was greater in the low-density treatment than in the high-density treatment. Our results demonstrate that the effects of ALAN on plant growth can be altered by soil moisture and plant density. Consequently, the effects of ALAN on plants in nature may not be consistent with existing frameworks that do not account for critical abiotic variables such as water availability or biotic interactions between plants such as competition.
Address Blandy Experimental Farm, University of Virginia, 400 Blandy Farm Lane, Boyce, VA, 22620, USA
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Language English Summary Language Original Title
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ISSN 0029-8549 ISBN Medium
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Notes PMID:32533357 Approved no
Call Number GFZ @ kyba @ Serial 3003
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