FIGURE 8.

(A) Efficiency of open photosystem II (PSII) centers (traps) during exposure to each respective growth PPFD, (B) fraction of PSII reaction centers (traps) that are closed, 1 – q_P = (F – F_o′)/(F_m′ – F_o′) (circles), and PSII efficiency at the degree of center closure (F_v′/F_m′ × q_P; squares) under each respective growth PPFD, and (C) the efficiency of PSII in the dark (F_v/F_m) in L. gibba fronds grown under each respective PPFD. Dark F_v/F_m was determined immediately upon removal of fronds from growth light conditions (– Recovery) and again after 30 min in low light (+ Recovery). F_m′, maximal fluorescence under actinic light; F_v′, variable fluorescence under actinic light (F_m′ – minimal fluorescence F_o′); PSII, photosystem II; q_P, photochemical quenching. Mean values ± standard deviations, n = 3 for all growth PPFDs; different lower-case letters signify statistical differences at P < 0.05 via one-way analysis of variance and post hoc Tukey–Kramer HSD test.