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Author Radetsky L.; Patel J. S.; Rea M. S.
Title Continuous and Intermittent Light at Night, Using Red and Blue LEDs to Suppress Basil Downy Mildew Sporulation Type Journal Article
Year 2020 Publication HortScience Abbreviated Journal
Volume 55 Issue 4 Pages 483-486
Keywords Animals; Plants
Abstract Lighting from red and blue light-emitting diodes (LEDs) is common for crop production in controlled environments. Continuous application of red or blue light at night has been shown to suppress sporulation by Peronospora belbahrii, the causal organism of basil downy mildew (DM), but the suppressing effects of intermittent applications of red and blue LEDs have not been thoroughly researched. This study examined the effects of red (λmax = 670 nm) and blue (λmax = 458 nm) LED top lighting, at two photosynthetic photon flux densities (PPFD = ≈12 and ≈60 µmol·m−2·s−1), using continuous (10-hour) nighttime and two intermittent nighttime exposures, to suppress basil DM sporulation. The two intermittent treatments consisted of one 4-hour exposure and three 1.3-hour exposures spaced 3 hours apart. Continuous nighttime treatments with blue or red LED top lighting at ≈60 µmol·m−2·s−1 were able to suppress basil DM sporulation by more than 99%. At a given nighttime dose of light that did not completely suppress sporulation, continuous lighting was more effective than intermittent lighting, and for these partially suppressing doses, red LEDs were not significantly different from blue LEDs for suppressing sporulation. The present study showed that horticultural lighting systems using red and blue LEDs to grow crops during the day can also be used at night to suppress basil DM sporulation by up to 100%.
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Call Number UP @ altintas1 @ Serial 3143
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Author Maggi, E.; Bertocci, I.; Benedetti-Cecchi, L.
Title Light pollution enhances temporal variability of photosynthetic activity in mature and developing biofilm Type Journal Article
Year 2020 Publication Hydrobiologia Abbreviated Journal Hydrobiologia
Volume 847 Issue 7 Pages 1793-1802
Keywords Plants; Ecology
Abstract Artificial light at night (ALAN) has been recently recognized as a threat for aquatic systems, but a comprehensive knowledge of its effects is still lacking. A fundamental question is whether and how ALAN might affect temporal variability of communities, thus undermining the stability of mature assemblages or influencing the colonization process. Here we investigated the role of ALAN on temporal variability of total biomass and maximum photosynthetic efficiency of marine autotrophic biofilms colonizing Mediterranean high-shore rock surfaces while controlling for density of their main grazers. Results showed stability in total biomass, but an increase in maximum photosynthetic efficiency from unlit to lit conditions, which suggested a temporal change in composition and/or abundance of different taxa within mature assemblages. The effect was weaker during the colonization process; in this case, density of grazers acted in the opposite direction of ALAN. We suggest that the addition of light at times when it would not be naturally present may affect the temporal variability of a variety of functioning in aquatic systems, depending on species-specific sensitivities to ALAN within microbial assemblages and/or indirect effects mediated by their consumers. We highlight to further investigate the role of this emergent topic in aquatic ecology.
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ISSN 0018-8158 ISBN Medium
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Call Number UP @ altintas1 @ Serial 3146
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Author Elkins, C.; Van Iersel, M. W.
Title Supplemental Far-red Light-emitting Diode Light Increases Growth of Foxglove Seedlings Under Sole-source Lighting Type Journal Article
Year 2020 Publication HortTechnology Abbreviated Journal
Volume 30 Issue 5 Pages 564-569
Keywords Plants
Abstract Seedlings may be grown indoors where environmental conditions can be precisely controlled to ensure consistent and reliable production. The optimal spectrum for production under sole-source lighting is currently unknown. Far-red light (λ = 700–800 nm) typically is not a significant part of the spectrum of light-emitting diode (LED) grow lights. However, far-red light is photosynthetically active and can enhance leaf elongation, which may result in larger leaves and increased light interception. We hypothesized that adding far-red light to sole-source lighting would increase the growth of ‘Dalmatian Peach’ foxglove (Digitalis purpurea) seedlings grown under white LED lights, potentially shortening production times. Our objective was to evaluate the effect of far-red light intensities, ranging from 4.0 to 68.8 µmol·m−2·s−1, on the growth and morphology of foxglove seedlings. Foxglove seedlings were grown in a growth chamber with a photosynthetic photon flux density (PPFD) of 186 ± 6.4 μmol·m−2·s−1 and supplemental far-red light intensities ranging from 4.0 to 68.8 µmol·m−2·s−1. As far-red light increased, shoot dry weight, root dry weight, plant height, and plant height/number of leaves increased by 38% (P = 0.004), 20% (P = 0.029), 38% (P = 0.025), and 34% (P = 0.024), respectively, while root weight fraction decreased 16% (P = 0.034). Although we expected supplemental far-red light to induce leaf and/or stem expansion, specific leaf area and compactness (two measures of morphology) were unaffected. Because a 37% increase in total photon flux density (PPFD plus far-red light) resulted in a 34.5% increase in total plant dry weight, the increased growth likely was due to increased photosynthesis rather than a shade-acclimation response. The growth response was linear across the 4.0 to 68.8 µmol·m−2·s−1 range of far-fed light tested, so we were unable to determine a saturating far-red photon flux density.
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Call Number UP @ altintas1 @ Serial 3266
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Author Reinberg, A.; Smolensky, M.H.; Touitou, Y.
Title The full moon as a synchronizer of circa-monthly biological rhythms: Chronobiologic perspectives based on multidisciplinary naturalistic research Type Journal Article
Year 2016 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 33 Issue 5 Pages 465-479
Keywords Moonlight; Commentary; Animals; Plants; Human Health
Abstract Biological rhythmicity is presumed to be an advantageous genetic adaptation of fitness and survival value resulting from evolution of life forms in an environment that varies predictably-in-time during the 24 h, month, and year. The 24 h light/dark cycle is the prime synchronizer of circadian periodicities, and its modulation over the course of the year, in terms of daytime photoperiod length, is a prime synchronizer of circannual periodicities. Circadian and circannual rhythms have been the major research focus of most scientists. Circa-monthly rhythms triggered or synchronized by the 29.5 day lunar cycle of nighttime light intensity, or specifically the light of the full moon, although explored in waterborne and certain other species, have received far less study, perhaps because of associations with ancient mythology and/or an attitude naturalistic studies are of lesser merit than ones that entail molecular mechanisms. In this editorial, we cite our recent discovery through multidisciplinary naturalistic investigation of a highly integrated circadian, circa-monthly, and circannual time structure, synchronized by the natural ambient nyctohemeral, lunar, and annual light cycles, of the Peruvian apple cactus (C. peruvianus) flowering and reproductive processes that occur in close temporal coordination with like rhythms of the honey bee as its pollinator. This finding led us to explore the preservation of this integrated biological time structure, synchronized and/or triggered by environmental light cues and cycles, in the reproduction of other species, including Homo sapiens, and how the artificial light environment of today in which humans reside may be negatively affecting human reproduction efficiency.
Address (up) a Unite de Chronobiologie , Fondation A de Rothschild , Paris cedex 19 , France
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Language English Summary Language Original Title
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ISSN 0742-0528 ISBN Medium
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Notes PMID:27019304 Approved no
Call Number LoNNe @ kyba @ Serial 1460
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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 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 (up) 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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