Table 1.

Impact of different CO₂/O₂ ratios under elevated temperature on the formation of CPs and CAT and APX activities

Experimental condition [EC]	CO2 [ppm]	PPFD [μmol photons m−2 s−1]	TL [°C]	rCP [%]	CAT [nkat mg−1 DW]	APX [nkat mg−1 DW]
EC 1	38	715	35.9/39.2	58.7	34.7	0.34
EC 2	10,000	715	35.9/39.8	3.0	18.4	0.27
EC 3	380	0	36.3/41.9	18.2	20.4	0.29
EC 4	380	715	36.6/41.0	41.3	22.2	0.31

Individual R. glacialis plants were exposed to different experimental conditions [EC]. During exposure, CO₂ concentration and leaf temperature (TL; mean/maximum) were controlled, and mean solar irradiation (PPFD) was monitored. After 2.5 h of exposure, the relative frequency of chloroplast protrusions (rCP) and the activities of catalase (CAT) and ascorbate peroxidase (APX) were determined