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Algae 1994;9(2): 217-223. |
| The Effect of Daylength and Photon Fluence Rate on the Growth of Griffithsia schousboei (Ceramiaceae, Rhodophyta) from Natal, South Africa
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| Fergus J. Molloy, Alan T. Critchley
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Department of Botany, University of Natal. Department of Botany, University of the Witwatersrand
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| ABSTRACT |
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The marine rhodophyte Griffithsia schousboei (Ceramiales) was exposed to various experimental combinations of daylength and photon fluence rate in the laboratory. Cell length increased, though not proportionally, with longer daylengths. During 16:8 light/dark cycles photon fluence rate had little effect on cell length. Cell division decreased slightly during higher photon fluence rates and was maximal between daylengths of 12-24h. Photon fluence rate was varied in accordance with varying daylength so that regardless of daylength plants received the same amount of light (Mean Daily Illuminance MDI). Low Photon fluence rates were effective in compensating for differences in daylength with regard to cell length and, to a lesser degree, cell division. Cell division was found to occur only during dark periods (in a light/dark cycle) and was found to follow an endogenous rhythm. Cellular elongation also followed a rhythm but was found not to be endogenous.
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| Key words:
Griffithsia schousboei, South Africa, daylength, photon fluence rate, cell length, cell division |
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