Some effects of humidity on the light reaction of photosynthesis in the lichens Cladonia impexa and Collema flaccidium |
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Authors: | BJÖRN SIGFRIDSSON |
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Institution: | University of Lund, Department of Plant Physiology, Box 7007, S-220 07 Lund 7, Sweden |
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Abstract: | Luminescence and fluorescence were measured at different relative humidities in the lichen Cladonia impexa Harm. Both parameters showed a constant value at relative humidities lower than 80%: thereafter they increased. Low relative humidity was found to decrease energy transfer from chlorophyll b to chlorophyll a. inhibit electron transport, lower electron holding capacity on the reduced side of photosystem two and impair far-red-induced afterglow, reflecting photophosphorylation. In Collema flaccidium Ach. Ach. energy transfer from the accessory pigments phycocyanin and phycoerythrin to chlorophyll a was only possible at high relative humidity. The results are interpreted as due to conformational changes caused by changed water content in the lichen. |
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Keywords: | Cladonia impexa Collema flaccidium fluorescence humidity lichens luminescence photosynthesis |
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