Deschampsia antarctica Desv. primary photochemistry performs differently in plants grown in the field and laboratory

摘要

Primary photochemistry of photosystem II (F_v/F_m) of the Antarctic hair grass Deschampsia antarctica growing in the field (Robert Island, Maritime Antarctic) and in the laboratory was studied. Laboratory plants were grown at a photosynthetic photon flux density (PPFD) of 180 μmol m~(-2) s~(-1) and an optimal temperature (13 ± 1.5℃) for net photosynthesis. Subsequently, two groups of plants were exposed to low temperature (4 ± 1.5℃ dayight) under two levels of PPFD (180 and 800 μmol m~(-2) s~(-1)) and a control group was kept at 13 ± 1.5℃ and PPFD of 800 μmol m~(-2) s~(-1) Chlorophyll fluorescence was measured during several days in field plants and weekly in the laboratory plants. Statistically significant differences were found in F_v/F_m (=0.75-0.83), F_0 and F_m values of field plants over the measurement period between days with contrasting irradiances and temperaturernlevels, suggesting that plants in the field show high photo-synthetic efficiency. Laboratory plants under controlled conditions and exposed to low temperature under two light conditions showed significantly lower F_v/F_m and F_m. Moreover, they presented significantly less chlorophyll and carotenoid content than field plants. The differences in the performance of the photosynthetic apparatus between field-and laboratory-grown plants indicate that measurements performed in ex situ plants should be interpreted with caution.