Table 3. Changes in PSII and PSI components in fronds of Hymenoglossum cruentum and Hymenophyllum dentatum measured at their respective light saturation points (Is).

PSII parameters: Y_PSII, photochemical quantum yield of PSII; Y_NPQ, regulated heat dissipation quantum yield; Y_NO, non-regulated heat dissipation quantum yield; and ETR_II, electron transport at the PSII. PSI parameters: Y_PSI, photochemical quantum yield of PSI; Y_ND, non-photochemical quantum yield caused by a donor side limitation; Y_NA, non-photochemical quantum yield caused by an acceptor side limitation, and ETR_I, electron transport rate at the PSI. Values correspond to mean ± SE (n = 4).

Is	IsH.cru = 24.6 (μmol photons m-2 s-1)		IsH.den = 40.5 (μmol photons m-2 s-1)
Species	H. cruentum	H. dentatum	H. cruentum	H. dentatum
PSII
YPSII	0.42 ± 0.01	0.60 ± 0.03**	0.31 ± 0.01	0.55 ± 0.04**
YNPQ	0.30 ± 0.01	0.08 ± 0.02*	0.43 ± 0.02	0.11 ± 0.04**
YNO	0.28 ± 0.01	0.32 ± 0.01*	0.26 ± 0.02	0.34 ± 0.01*
ETRII	2.98 ± 0.05	3.1 ± 0.20ns	3.64 ± 0.13	4.4 ± 0.44ns
PSI
YPSI	0.62 ± 0.04	0.85 ± 0.10ns	0.44 ± 0.04	0.60 ± 0.14*
YND	0.40 ± 0.05	0.00 ± 0.00*	0.57 ± 0.05	0.06 ± 0.04**
YNA	0.03 ± 0.03	0.15 ± 0.10ns	0.02 ± 0.01	0.14 ± 0.04*
ETRI	4.44 ± 0.23	3.51 ± 0.79ns	5.24 ± 0.36	5.56 ± 1.39ns

Levels of significance: ns, not significant;

*, P <0.05;

**, P <0.001.