Table IV.

PSII efficiency of V. major grown in GCs or OD under natural sunlight

V. major	Efficiency of PSII Units
GCs
Control (5)	0.72  ± 0.03 (D)
Stress (7)	0.04  ± 0.04 (L)
1.5 h of recovery (12)	0.33  ± 0.12 (D)
2.5 h of recovery (19)	0.37  ± 0.12 (D)
OD
Control (11)	0.77  ± 0.02 (D)
Stress (13)	0.15  ± 0.08 (L)
1 h of recovery (14)	0.38  ± 0.08 (D)
2.5 h of recovery (22)	0.47  ± 0.13 (D)

Measurements were taken after 12 h of darkness (control), at the end of the high-light treatment (stress), and during recovery in darkness at room temperature. PSII efficiency is either that of open PSII units in darkness (F_v/F_m; D) or that at the actual degree of closure in the light ([F_m′ − F]/F_m′, where F_m′ is the maximal fluorescence measured in the light and F is the actual fluorescence measured in the light; L). The number of leaves sampled at each time is indicated in parentheses. Data are means ± sd.