CO2 gas exchange was measured with a CIRAS-2 portable photosynthesis
system (PP Systems, USA) at 25 C, 65% relative humidity,
saturating light intensity of 1200 lmol m2 s1 and different
CO2 concentration (400 or 1200 lmol mol1). Leaf chamber temperature,
relative humidity, light intensity and CO2 concentration
were controlled by automatic control device of the CIRAS-2 portable
photosynthetic system.