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- Title
Comparisons of photosynthesis and photoinhibition in the CAM vine <em>Hoya australis</em> and several C<sub>3</sub> vines growing on the coast of eastern Australia.
- Authors
Adams, W. W.; Terashima, I.; Brugnoli, E.; Demmig, B.
- Abstract
The CAM vine <em>Hoya australis</em> and three C3 vines, <em>Smilax australis</em>, <em>Ipomoea pes-caprae</em> and <em>Kennedia rubicunda</em>, were studied at a site on the coast of northeastern New South Wales, Australia. The level of CAM activity (nocturnal acid accumulation) was comparable in <em>H. australis</em> growing in full sunlight and in deep shade. Acclimation to shade by <em>H. australis</em> was indicated by thinner leaves, increased chlorophyll content, decreased chlorophyll a/b ratios, lower dark respiration rates, and lower light compensation points. When growing in full sunlight H. australis exhibited reductions in photochemicai efficiency, as indicated by reduced quantum yields and Fv/Fm fluorescence from PS II as well as low rates of photosynthesis at high light. Sun leaves of <em>H. australis</em> experienced a massive quenching of fluorescence from PS II during normal exposure to midday irradiance which was rapidly reversible under low irradiance conditions in the late afternoon. This quenching indicated a reduction in photochemical efficiency, part of which could be accounted for by an increase in non-radiative energy dissipation, while part of it was due to one or more processes not yet identified. Changes in PS II fluroscense from shade <em>H. australis</em> exposed to full sunlight suggest a decrease in the rate constant for photochemistry indicative of damage to the reaction centre, as well as an increase in non-radiative energy dissipation. The C3 vine <em>S. australis</em> was also shade tolerant, but exhibited little evidence of photoinhibition when growing in full sunlight. <em>Ipomoea pescaprae</em> and <em>K. rubicunda</em>, both of which were apparently shade intolerant (being found only in full sunlight), possessed high quantum yields and much higher photosynthetic capacities than either <em>H. australis</em> or <em>S. australis</em>. From this study, and several others, it appears that plants possessing CAM experience photoinhibition to a greater degree than do C3 species in full sunlight under na...
- Subjects
AUSTRALIA; HOYA; ASCLEPIADOIDEAE; CRASSULACEAN acid metabolism; PHOTOSYNTHESIS
- Publication
Plant, Cell & Environment, 1988, Vol 11, Issue 3, p173
- ISSN
0140-7791
- Publication type
Article
- DOI
10.1111/j.1365-3040.1988.tb01134.x