Camellia Japonica leaves are used as samples for studying respiration rates by a quantitative method of measurement at accurately controlled temperatures in the -3 to +30 degrees C range. O-2 consumption and CO2 production are analyzed by a quadrupole mass spectrometer in a high vacuum chamber. It was found that for aerobic respiration the stoichiometric transformation of O-2 into CO2 follows pseudo-first-order kinetics, with a reaction rate constant which at 20 degrees C is of k = 0.080 +/- 0.003 days (1) for 93 g of wet leaves. Measurements, when analyzed according to an Arrhenius-like behaviour, lead to an activation energy of 85 +/- 8 kJ mol (1), but a pronounced (convex or super-Arrhenius) deviation is observed. (C) 2009 Elsevier B. V. All rights reserved.