Cold-acclimation limits low temperature induced photoinhibition by promoting a higher photochemical quantum yield and a more effective PSII restoration in darkness in the Antarctic rather than the Andean ecotype of Colobanthus quitensis Kunt Bartl (Cariophyllaceae)

Table 2 Effect of cold acclimation on photosynthetic parameters of plants of both ecotypes of C. quitensis subjected to PhT and a recovery period

			Photosynthetic parameters
	Ecotype	Treatment	Rd	ΦCO₂	A_max	LCP
Acclimation			(μmol CO₂m^-2s^-1)	(mol mol^-1photons)	(μmol CO₂m^-2s^-1)	(μmol photons m^-2s^-1)
Non- acclimated	Andean	Initial	−1.4 ± 0.2 (a)	0.034 ± 0.004 (de)	3.9 ± 0.5 (cde)	31 ± 1 (bcd)
		PhT.	−1.3 ± 0.3 (a)	0.021 ± 0.002 (e)	2.5 ± 0.2 (f)	68 ± 1 (a)
		Recovery	−0.7 ± 0.1 (de)	0.025 ± 0.003 (de)	4.3 ± 0.2 (bcde)	29 ± 5 (bcde)
	Antarctic	Initial	−1.1 ± 0.2 (abcd)	0.040 ± 0.003 (cd)	4.7 ± 0.5 (bcd)	23 ± 3 (cdef)
		PhT.	−1.0 ± 0.1 (abcde)	0.020 ± 0.003 (e)	2.3 ± 0.3 (f)	42 ± 4 (b)
		Recovery	−0.6 ± 0.1 (e)	0.039 ± 0.002 (cd)	4.5 ± 0.4 (bcde)	20 ± 6 (def)
Cold- acclimated	Andean	Initial	−1.3 ± 0.2 (ab)	0.050 ± 0.010 (bc)	4.5 ± 0.5 (bc)	24 ± 4 (cdef)
		PhT.	−0.7 ± 0.1 (de)	0.025 ± 0.006 (de)	3.2 ± 0.5 (ef)	36 ± 10 (bc)
		Recovery	−0.7 ± 0.1 (e)	0.051 ± 0.005 (bc)	4.7 ± 0.7 (bcd)	21 ± 8 (def)
	Antarctic	Initial	−0.8 ± 0.3 (abc)	0.076 ± 0.003 (a)	5.3 ± 0.2 (b)	33 ± 2 (bcd)
		PhT.	−0.5 ± 0.2 (bcde)	0.034 ± 0.004 (de)	3.8 ± 0.1 (cde)	33 ± 6 (bcd)
		Recovery	−0.6 ± 0.2 (cde)	0.064 ± 0.009 (ab)	8 ± 1 (a)	15 ± 1 (f)

Rd, dark respiration rate; Φ CO₂, quantum yield of CO₂ uptake; A_max, maximal rate of net photosynthesis; LCP, light compensation point. These parameters were obtained from the analysis of light response curves, performed at 4°C and 360 ppm of CO₂ from the Sure 6. Results show mean values ± SE of two separate experiments with 3 replicates each. Different letters represent significant differences between acclimation, treatment and ecotypes P<0.05 using three-way ANOVA.

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