Measurements of photosynthesis and respiration
Measurements of photosynthetic capacity were made using a LiCor LI-6400
infra-red gas analyser, at a temperature of 20°C in an atmosphere of
2000 µl l-1 CO2 and an irradiance of
2000 µmol m−2 s−1 provided by a warm
white LED (colour temperature 2800–3200 K). Measurements of
photosynthesis and respiration under growth conditions were carried out
using the same gas analyser, in the growth cabinet where plants were
grown, using ambient air. The gas analyser was placed in the cabinet and
allowed to equilibrate for at least 1 hour prior to any measurements.
The analyser chamber was placed to give a light intensity in the chamber
equivalent to that of plants during growth. Respiration was measured by
interrupting illumination, covering the plant and analyser chamber with
aluminium foil. Data were analysed using Analysis of Variance, followed
by Tukey post-hoc tests in SPSS (IBM).