Journal Article

PreJuSER-20008

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Molecular iodine emission rates and photosynthetic performance of different thallus parts of Laminaria digitata (Phaeophyceae) during emersion

Nitschke, U. ; Ruth, A. A. ; Dixneuf, S.FZJ* ; Stengel, D. B.

2011
Springer Berlin

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Please use a persistent id in citations: doi:10.1007/s00425-010-1334-3

Abstract: The emission of molecular iodine (I(2)) from the stipe, the meristematic area and the distal blade of the brown macroalga Laminaria digitata (Hudson) Lamouroux (Phaeophyceae) was monitored under low light and dark conditions. Photosynthetic parameters were determined to investigate both the extent of stress experienced by different thallus parts and the effects of emersion on photosynthesis. Immediately after air exposure, intense I(2) emission was detectable from all thallus parts. I(2) emission declined continuously over a period of 180 min following the initial burst, but was not affected by the light regime. The total number of mole of I(2) emitted by stipes was approximately 10 times higher than those emitted from other thallus parts. Initial I(2) emission rates (measured within 30 min of exposure to air) were highest for stipes (median values: 2,999 and 5,222 pmol g(-1) dw min(-1) in low light and dark, respectively) and lower, by one order of magnitude, for meristematic regions and distal blades. After exposure to air for between 60 and 180 min, I(2) emission rates of all thallus parts were reduced by 70-80%. Air exposure resulted in a decrease of the maximum photosystem II (PSII) efficiency (F(v)/F(m)) by 3%, and in a 25-55% increase of the effective PSII quantum efficiency (F(v)/F'(m)); this was caused by a higher fraction of open reaction centres (q(P)), whereas the efficiency of the latter in capturing energy (F'(v)/F'(m)) remained constant. The results indicate the presence of an iodine pool which is easily volatilised and depleted due to air exposure, even under apparently low stress conditions.

Keyword(s): Air (MeSH) ; Biomass (MeSH) ; Iodine: analysis (MeSH) ; Laminaria: physiology (MeSH) ; Photosynthesis: physiology (MeSH) ; Plant Leaves: physiology (MeSH) ; Time Factors (MeSH) ; Water (MeSH) ; Iodine ; Water ; J ; Emersion (auto) ; Emission rate (auto) ; IBBCEAS (auto) ; Laminaria (auto) ; Molecular iodine (auto) ; Photosynthesis (auto)

Note: The authors thank Professor Colin O'Dowd (School of Physics and Ryan Institute, NUI Galway), Dr. Solene Connan (Botany and Plant Science and Ryan Institute, NUI Galway) and Dr. Stewart Vaughan (School of Chemistry, University of Leeds, UK) for comments on the experimental design and Dr. Jerome Sheahane (Statistics and Applied Mathematics, School of Mathematics, NUI Galway) for his help with statistical analyses. UN and SD gratefully appreciate financial support through the Irish Research Council for Science, Engineering and Technology (IRCSET 'Embark Initiative').

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Contributing Institute(s):

1. Troposphäre (IEK-8)

Research Program(s):

1. Atmosphäre und Klima (P23)

Appears in the scientific report 2011

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