We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Non-photosynthetic enhancement of growth by high CO<sub>2</sub> level in the nitrophilic seaweed Ulva rigida C. Agardh (Chlorophyta).
- Authors
Gordillo, Francisco J. L.; Niell, F. Xavier; Figueroa, Félix L.
- Abstract
The effects of increased CO2 levels (10,000 μl l-1) in cultures of the green nitrophilic macroalga Ulva rigida C. Agardh were tested under conditions of N saturation and N limitation, using nitrate as the only N source. Enrichment with CO2 enhanced growth, while net photosynthesis, gross photosynthesis, dark respiration rates and soluble protein content decreased. The internal C pool remained constant at high CO2, while the assimilated C that was released to the external medium was less than half the values obtained under ambient CO2 levels. This higher retention of C provided the source for extra biomass production under N saturation. In N-sufficient thalli, nitrate-uptake rate and the activity of nitrate reductase (EC 1.6.6.1) increased under high CO2 levels. This did not affect the N content or the internal C:N balance, implying that the extra N-assimilation capacity led to the production of new biomass in proportion to C. Growth enhancement by increased level of CO2 was entirely dependent on the enhancement effect of CO2 on N-assimilation rates. The increase in nitrate reductase activity at high CO2 was not related to soluble carbohydrates or internal C. This indicates that the regulation of N assimilation by CO2 in U. rigida might involve a different pathway from that proposed for higher plants. The role of organic C release as an effective regulatory mechanism maintaining the internal C:N balance in response to different CO2 levels is discussed.
- Subjects
GREEN algae; CARBON dioxide; PHOTOSYNTHESIS; CARBON; AGAR family; NITROGEN supersaturation
- Publication
Planta: An International Journal of Plant Biology, 2001, Vol 213, Issue 1, p64
- ISSN
0032-0935
- Publication type
Article
- DOI
10.1007/s004250000468