Fig. 2.

NPQ and linear photosynthetic ETR in Arabidopsis WT and mutant lines. (A) Quantum yield of NPQ [Y(NPQ)] was performed using attached leaves from plants grown under short-day conditions for 8 wk. White and black blocks indicate light (75 μE m⁻²⋅s⁻¹) and darkness periods, respectively. Each data point is the average of at least four determinations, and SEs are represented by error bars. (B) Relative ETRs of PSII, ETR(II), were determined during stepwise increasing photosynthetically active radiation (PAR) in plants grown as in A. Each data point is the mean of the ETR(II) from at least five leaves from different plants, and SEs are presented.