Photosynthetic light and CO2 response
curves
Photosynthetic response curves to light (A -PAR),
CO2 (A -C i) were performed
in completely expanded leaves from 45 day-old plants of all genotypes
using a portable infrared gas exchange analyser (IRGA) (LiCor 6400XT,
Lincoln, NE, USA). A -PAR curves were measured using 400 ppm
CO2, block temperature at 28 °C and 10% of blue light,
whilst A -C i were carried out using 1000
µmol photons m-2 s-1. A three
component exponential rise to maximum equation was used to fit the
photosynthetic curves: A = a (1 -e-bx ) + c , where A =
photosynthetic rate, x = PAR or substomatal CO2concentration (C i), and a, b, c are parameters
estimated by the non-linear regression (Watling, Press & Quick, 2000).