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Author Radetsky L.; Patel J. S.; Rea M. S. url  doi
openurl 
  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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  Notes Approved no  
  Call Number (down) UP @ altintas1 @ Serial 3143  
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Author Maggi, E.; Bertocci, I.; Benedetti-Cecchi, L. url  doi
openurl 
  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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  Series Volume Series Issue Edition  
  ISSN 0018-8158 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number (down) UP @ altintas1 @ Serial 3146  
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Author Elkins, C.; Van Iersel, M. W. url  doi
openurl 
  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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  Notes Approved no  
  Call Number (down) UP @ altintas1 @ Serial 3266  
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Author Bennie, J.; Davies, T.W.; Cruse, D.; Inger, R.; Gaston, K.J.; Lewis, O. url  doi
openurl 
  Title Artificial light at night causes top-down and bottom-up trophic effects on invertebrate populations Type Journal Article
  Year 2018 Publication Journal of Applied Ecology Abbreviated Journal J Appl Ecol  
  Volume 55 Issue 6 Pages 2698-2706  
  Keywords Ecology; Animals; Plants  
  Abstract Globally, many ecosystems are exposed to artificial light at night. Nighttime lighting has direct biological impacts on species at all trophic levels. However, the effects of artificial light on biotic interactions remain, for the most part, to be determined.

We exposed experimental mesocosms containing combinations of grassland plants and invertebrate herbivores and predators to illumination at night over a 3‐year period to simulate conditions under different common forms of street lighting.

We demonstrate both top‐down (predation‐controlled) and bottom‐up (resource‐controlled) impacts of artificial light at night in grassland communities. The impacts on invertebrate herbivore abundance were wavelength‐dependent and mediated via other trophic levels.

White LED lighting decreased the abundance of a generalist herbivore mollusc by 55% in the presence of a visual predator, but not in its absence, while monochromatic amber light (with a peak wavelength similar to low‐pressure sodium lighting) decreased abundance of a specialist herbivore aphid (by 17%) by reducing the cover and flower abundance of its main food plant in the system. Artificial white light also significantly increased the food plant's foliar carbon to nitrogen ratio.

We conclude that exposure to artificial light at night can trigger ecological effects spanning trophic levels, and that the nature of such impacts depends on the wavelengths emitted by the lighting technology employed.

Policy implications. Our results confirm that artificial light at night, at illuminance levels similar to roadside vegetation, can have population effects mediated by both top‐down and bottom‐up effects on ecosystems. Given the increasing ubiquity of light pollution at night, these impacts may be widespread in the environment. These results underline the importance of minimizing ecosystem disruption by reducing light pollution in natural and seminatural ecosystems.
 
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-8901 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number (down) NC @ ehyde3 @ Serial 2086  
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Author Grubisic, M.; Singer, G.; Bruno, M.C.; van Grunsven, R.H.A.; Manfrin, A.; Monaghan, M.T.; Hölker, F. url  doi
openurl 
  Title A pigment composition analysis reveals community changes in pre-established stream periphyton under low-level artificial light at night Type Journal Article
  Year 2018 Publication Limnologica Abbreviated Journal  
  Volume 69 Issue Pages 55-58  
  Keywords Plants; Ecology  
  Abstract Freshwaters are increasingly exposed to artificial light at night (ALAN), yet the consequences for aquatic primary producers remain largely unknown. We used stream-side flumes to expose three-week-old periphyton to LED light. Pigment composition was used to infer community changes in LED-lit and control periphyton before and after three weeks of treatment. The proportion of diatoms/chrysophytes decreased (14%) and cyanobacteria increased (17%) in lit periphyton in spring. This may reduce periphyton nutritional quality in artificially-lit waters.  
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  Series Volume Series Issue Edition  
  ISSN 0075-9511 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number (down) LoNNe @ schroer @ Serial 1791  
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