Resumo

SOBRADO, M.A. Differential leaf gas exchange responses to salinity and drought in the mangrove tree Avicecennia germinans (Avicenniaceae). Rev. biol. trop [online]. 2006, vol.54, n.2, pp.371-375. ISSN 0034-7744.

Leaf gas exchange was assessed in Avicennia germinans L. grown under different NaCl concentrations (0-40‰), after salt-relief, and then during drought. Stomatal conductance (g_s) and net photosynthetic rate (P_n) decreased with increasing NaCl concentration, and intrinsic water use efficiency (P_n / g_s) increased. Under desalinization P_n / g_s declined. Thus, g_s did not change in plants grown at low NaCl concentration (10‰), but increased up to 30-32% at higher NaCl concentration (20 - 40‰). However, P_n was only slightly enhanced (10- 15%). Under drought, P_n decreased by as much as 46% in plants grown at low NaCl concentration (10‰) and by 22% at high NaCl concentration (40‰). Thus, P_n / g_s decreased and water use efficiency was lower during drought compared to estimates prior to salt-relief. Rev. Biol. Trop. 54(2): 371-375. Epub 2006 Jun 01.

Palavras-chave : Avicennia germinans; mangrove; NaCl; stomatal conductance; water use efficiency.

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