Premium
Photoinhibition in the Antarctic moss Grimmia antarctici Card when exposed to cycles of freezing and thawing
Author(s) -
LOVELOCK C. E.,
OSMOND C.B.,
SEPPELT R. D.
Publication year - 1995
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1995.tb00200.x
Subject(s) - photoinhibition , moss , photosynthesis , botany , chlorophyll fluorescence , carbon assimilation , chemistry , biology , photosystem ii
Freezing and thawing of the endemic moss species Grimmia antarctici Card, caused photoinhibition. When snow cover was removed from moss in the field, resulting in exposure to fluctuating temperatures and light conditions, photoinhibition, measured as a reduction in the ratio of variable to maximum chlorophyll a fluorescence (F v /F m ), was observed. The extent of photoinhibition was highly variable and appeared to be reversible during periods of warmer temperatures. A series of controlled laboratory studies found that the light conditions that prevail between freezing and thawing events influenced the recovery from photoinhibition observed during freezing and thawing, with low light conditions facilitating the greatest rates of recovery. After four cycles of freezing and thawing, recovery from photoinhibition in hydrated moss was achieved within 12 h of transfer to 5°C and 15 μmol quanta m −2 s −1 . These results favour the hypothesis that photoinhibition observed during freezing represents a protective process involving the down‐regulation of photo‐system II when photosynthetic carbon assimilation is limited by low temperatures.