Document Detail

Analysis of changes in minimal and maximal fluorescence yields with irradiance and o(2) level in tobacco leaf tissue.
MedLine Citation:
PMID:  16668147     Owner:  NLM     Status:  PubMed-not-MEDLINE    
The responses of minimal and maximal fluorescence yields of chlorophyll a to irradiance of actinic white light were determined by pulse modulated fluorimetry in leaf discs from tobacco, Nicotiana tabacum, at 1.6, 20.5, and 42.0% (v/v) O(2). Steady-state maximal fluorescence yield (F(m)', measured during a saturating light pulse) declined with increasing irradiance at all O(2) levels. In contrast, the steady-state minimal fluorescence yield (F(o)', measured during a brief dark interval) increased with irradiance relative to that recorded for the fully dark-adapted leaf (F(o)) or that observed after 5 minutes of darkness (F(o) (*)). The relative magnitude of this increase was somewhat greater and extended to higher irradiances at the elevated O(2) levels compared with 1.6% O(2). Suppression of F(o)' was only observed consistently at saturating irradiance. The results are interpreted in terms of the occurrence of photosystem II units possessing exceedingly slow turnover times (i.e. "inactive" units). Inactive units play an important role, along with thermal deactivation of excited chlorophyll, in determining the response of in vivo fluorescence yield to changes in irradiance. Also, a significant interactive effect of O(2) concentration and the presence or absence of far red light on oxidation of photosystem II acceptors in the dark was noted.
R B Peterson
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Plant physiology     Volume:  96     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  1991 May 
Date Detail:
Created Date:  2010-06-29     Completed Date:  2010-06-29     Revised Date:  2010-09-15    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  172-7     Citation Subset:  -    
Department of Biochemistry and Genetics, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06504.
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