Sobrado M. A. author text journal article 2008 In six dominant species of the Amazonian 'Bana' vegetation, leaf blade characteristics, pigment composition, and chlorophyll (Chl) fluorescence parameters were measured in young and mature leaves under field conditions. Leaf δ¹³C was comparable in the six species, which suggested that both expanding and expanded leaves contained organic matter fixed under similar intercellular and ambient CO₂ concentration (C _i/C _a). High leaf C/N and negative δ¹⁵N values found in this habitat were consistent with the extreme soil N-deficiency. Analysis of Chl and carotenoids showed that expanding leaves had an incomplete development of photosynthetic antenna when compared to adult leaves. Dynamic inactivation of photosystem 2 (PS2) at midday was observed at both leaf ages as F_v/F_m decreased compared to predawn values. Adult leaves reached overnight F_v/F_m ratios typical of healthy leaves. Overnight recovery of F_v/F_m in expanding leaves was incomplete. F₀ remained unchanged from midday to predawn and F_v tended to increase from midday to predawn. The recovery from midday depression observed in adult leaves suggested an acclimatory down-regulation associated with photo-protection and non-damage of PS2. acclimation; down regulation; leaf C/N; nitrogen deficiency; photo-protection; sclerophyllous leaves; species differences; δ13C; δ15N 10.1007/s11099-008-0033-9 https://ps.ueb.cas.cz/artkey/phs-200802-0007.php https://ps.ueb.cas.cz/artkey/phs-200802-0007.php continuing 46 2 202 2008 03003604 periodical academic journal