Infrared gas analyzer measurements (IRGA)
The gas exchange rate of 4week-old plants was measured using a LI-6400XT
portable photosynthesis system (Li-Cor Biosciences Inc.). Five
individual plants, grown under short-day conditions (8-h light provided
by cool white fluorescent bulbs, 100 µM
m-2s-1, 22 °C; 16-h dark, 20 °C)
were used for each experiment. For the light-dependent tests, the
whole-plant chamber was set up with the following parameters: 200
µmol/sec flow rate, 20◦C block temperature, 50–70% relative humidity,
and 400 µmol/mol [CO2]. For differential light conditions, the
plants were dark-exposed (0 PAR) for 30 min and then light-exposed (400
PAR) for 30 min followed by another dark (0 PAR) phase for 30 min. The
data was logged every 30 sec. The LI-6400XT portable photosynthesis
system (Li-Cor Biosciences Inc.) generates the raw data for the rate of
transpiration over time with a default value for the area of the plants.
Following the gas exchange rate measurement, ImageJ was used to
determine the plant’s area (Schindelin et al., 2012). The rate of
transpiration measurement was automatically standardized on the plant
area by adding this value to the raw data from the LI-6400XT device.
Furthermore, the time scale was modified in accordance with the
experiment. For instance, the graph’s x-axis can be modified to show 30
minutes on the negative scale and 60 minutes on the positive scale once
the time point 0 is set at 400 PAR light. Data presented are means of at
least three leaves from individual plants for each experiment.
Experiments were repeated at least three times.