Journal
PLANT PHYSIOLOGY AND BIOCHEMISTRY
Volume 120, Issue -, Pages 88-94Publisher
ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
DOI: 10.1016/j.plaphy.2017.09.025
Keywords
Chlorophyll fluorescence; 820 nm reflection; Photosynthetic activity; Rapid light-response curve; Sargassum thunbergii; Seasonal variability
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Funding
- National Natural Science Foundation of China [41376154]
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The present study evaluates the seasonal photosynthetic performances of Sargassum thunbergii via chlorophyll fluorescence technique. During summer and early winter, no significant change was observed in maximum photochemical efficiency (Fv/Fm), and performance index (Nabs). During late winter and early spring, Fv/Fm, and Plabs decreased significantly, implying that S. thunbergii photosystem II (PSII) suffered apparent photoinhibition. Subsequently, PSII gradually recovered during late spring and summer, as evidenced by an increase of both parameters. Throughout the year, the maximum decrease in the slope of MR/MR0 maintained low values indicated that photosystem I (PSI) was incative, the initial rate of P700(+) re-reduction maintained low value indicated that cyclic electron transport (CET) were inactive; nevertheless, a seasonal down-regulation of both PSI and CET during late winter and early spring could be detected. The weak performance of PSI and CET can potentially limit the flexibility in response to winter stress and result in a delayed recovery of PSII. In conclusion, the seasonal variability of S. thunbergii photosynthetic activity was characterized by three periods: active state, down-regulation and restoration. The rapid growth during early spring was accompanied by weak photosynthetic performance, indicating that the carbohydrates consumed during this period were derived from previously stored starch. (C) 2017 Elsevier Masson SAS. All rights reserved.
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