Figure 1.

Chamber for isotopic labelling of individual leaves. (A) Picture of the single leaf labelling chamber. The labelling system comprises of a reservoir chamber (1) in which the isotopically labelled sodium-bicarbonate is placed within a petri dish (2). The bicarbonate is acidified by injecting an excess of lactic acid through a rubber seal (3) into the petri dish, releasing labelled CO₂, which is homogenously dispersed within the chamber with a fan (4). The labelled air is pumped through a tubing system to the single leaf cuvette (5) or through a bypass (6) when exchanging leaves to be labelled. An adjustable table (7) is used to position the plants in relation to the external light source (8). (B) Scheme of the single leaf labelling chamber in use.