Table 2.

Slopes (αβ) and light respiration following the method of Yin et al. (2011) (R _L,Yin, μmol CO₂ m^–2 s^–1) or intercept values (Ф_PSII/) obtained under non-photorespiratory conditions according to different approaches, consisting of higher (Ф_PSII/ A/C _i or PPFD >400 μmol m^–2 s^–1) or lower (Yin PPFD <400 or PPFD <400 μmol m^–2 s^–1 and C _i >500 μmol mol^–1 air) susceptibilities to alternative electron sinks

For comparison, the original slopes (k) obtained when using the Ф_PSII/ relationship were already converted to αβ (αβ=4/k); the intercept refers to the parameter b in the equation: Ф_PSII = k +b.

		Slope (αβ)	Intercept (ФPSII/)	R L,Yin
N. tabacum	ФPSII/ (A/C i)	0.52±0.013	0.005±0.002
	ФPSII/ (PPFD >400)	0.36±0.011	–0.02±0.008*
	Yin (PPFD <400)	0.39±0.017		0.87±0.47
	Yin (PPFD <400 C i >500)	0.46±0.026		0.87±0.87
C. arabica	ФPSII/ (A/C i)	0.64±0.014	0.015±0.002*
	ФPSII/ (PPFD >400)	0.46±0.018	–0.011±0.007
	Yin (PPFD <400)	0.50±0.025		0.84±0.41
	Yin (PPFD <400 C i >500)	0.63±0.015		2.55±0.45*
L. gibertii	ФPSII/ФCO22 (A/C i)	0.56±0.019	0.014±0.004*
	ФPSII/ (PPFD>400)	0.37±0.011	–0.03±0.009*
	Yin (PPFD<400)	0.41±0.013		2.04±0.25*
	Yin (PPFD <400 C i >500)	0.50±0.018		3.14±1.02*

Values are the means ±standard error of four replicates per species.

An asterisk denotes respiration or intercepts significantly different from zero (P < 0.05).