期刊
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
卷 141, 期 -, 页码 70-74出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ecoenv.2017.03.016
关键词
Coastal marine; Photosynthesis; Saline ecosystem; Salt glands; SEM
资金
- Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) [1401/2013 - Edital 004/2013]
Mangrove sites are constantly under tidal regimes, where there is variation of dissolved oxygen and saline content in water. This study evaluated the effects of varying salinity in Avicennia schaueriana, an abundant species in the sea-mangrove-river interface. Seedlings of A. schaueriana were harvested at the riverbank and placed in different saline and nutrient solutions in a greenhouse in order to simulate a saline flow. After 7 acclimatization days, plants were exposed to the following saline concentrations: 0, 50, 170 and 250 mM NaCl, for a period of 30 days. After this, leaf gas exchange, chlorophyll a fluorescence, Falker chlorophyll index, leaf ultrastructure and micromorphology were evaluated. The highest saline concentration affected mainly the CO2 assimilation, internal CO2 concentration and the intrinsic efficiency of water use. The chlorophyll a fluorescence and Falker index were not significantly affected by any of the saline conditions, however chloroplast was damaged. Concomitantly, leaf salt glands clearly evidenced a higher salt secretion, when plants were submitted to the greatest saline concentration. The results indicated that A. schaueriana tolerates different salt concentration in the mangrove and excretes salt excess by salt gland, and this can attenuate the saline stress. However, when exposed to longer periods of higher salt fluxes the plant growth can be affected.
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