Table I.

Chlorophyll fluorescence quenching and ΔpH for intact chloroplasts

Sample	Actinic Light	q9-aa	qE	Fv/Fm	DEPS
	μmol PAR m−2 s−1				%
Dark	50	0.62  ± 0.02	0.08  ± 0.02	0.76  ± 0.01	4.0  ± 2.0
	600	0.84  ± 0.02	0.48  ± 0.03
Light	50	0.65  ± 0.01	0.54  ± 0.02	0.69  ± 0.02	58.0  ± 2.0
	600	0.82  ± 0.03	0.61  ± 0.02

Data are shown for chloroplasts isolated from dark-adapted and light-activated leaves. The coefficient of quenching of 9-aminoacridine (q-9aa) was calculated as the amplitude of quenching divided by total fluorescence. qE = (F_{m^r − Fm′)/Fm, where Fm^r is the recovered (5 min after addition of 5 μm DCMU) fluorescence levels. For details, see legend to Figure 2A. Data are the means (±se) of six to seven assays obtained from two different preparations of chloroplasts.}