Measurements were made on attached leaves in the growth
chamber with a portable gas exchange system (CIRAS-1; PP Systems,
Hertfordshire, UK), using a PLC broad leaf cuvette in closed
circuit mode. Transpiration rate (E), stomatal conductance (gs), net
photosynthetic rate (PN) and sub-stomatal CO2 concentration (Ci)
were recorded during measurements. Experiments were made at
ambient CO2 concentration, 130–170molm−2 s−1 PPFD, and at
the temperature and relative humidity prevailing in the growth
chamber. All measurements were taken in leaves illuminated for
3–4 h. The experiment was run with 3 different batches of plants,
and 7 plants per treatment were used for the measurements.