Simultaneous measurement of oxygen evolution and chlorophyll fluorescence from leaf pieces.

An apparatus is described which permits the simultaneous measurement of O(2) evolution and chlorophyll a fluorescence from illuminated discs or pieces of green leaves. O(2) is measured in the gas phase in a temperature-controlled chamber of approximately 5-milliliter capacity. Calibration is effected by injection of air through vents. Response time is approximately 1.5 seconds for O(2), and full scale deflection, in normal operating mode, is approximately 10 micromoles O(2). The apparatus may also be used to monitor fluorescence alone, in an open mode, in which gas is passed continuously through the chamber.