Different salt concentrations induce alterations both in photosynthetic parameters and salt gland activity in leaves of the mangrove Avicennia schaueriana.
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 250mM 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 CO2assimilation, internal CO2concentration 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.
Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil.
Janaina Dos Santos
JDS
Garcia
Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil.
Ândrea Carla
ÂC
Dalmolin
Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizontes 31270-901, Minas Gerais, Brazil.
Marcel Giovanni Costa
MGC
França
Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil. Electronic address: pamangabeira@uesc.br.
Pedro Antônio Oliveira
PAO
Mangabeira
D000064:Acclimatization / Q000187:drug effects*; D000818:Animals; D032407:Avicennia / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D045483:Rivers / Q000737:chemistry; D054712:Salinity; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology*; D053833:Wetlands
D002734:Chlorophyll; D012965:Sodium Chloride; D000077194:Chlorophyll A
Coastal marine; Photosynthesis; SEM; Saline ecosystem; Salt glands