INTERACTIONS AMONG PHOSPHATE UPTAKE,PHOTOSYNTHESIS, AND CHLOROPHYLL FLUORESCENCE IN NUTRIENT‐LIMITED CULTURES OF THE CHLOROPHYTE MICROALGA DUNALIELLA TERTIOLECTA1 |
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Authors: | Simon Roberts Kirsten Shelly John Beardall |
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Institution: | 1. School of Biological Sciences, PO Box 18, Monash University, Clayton, Victoria 3800, Australia;2. Author for correspondence: e‐mail . |
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Abstract: | Phosphate‐limited and phosphate‐sufficient continuous cultures of the marine chlorophyte microalga Dunaliella tertiolecta Butcher were examined for their responses to the addition of phosphate. Phosphate‐limited cultures showed a marked quenching of chl fluorescence following a pulse of phosphate. This response was absent from cells growing under phosphate‐sufficient conditions. Both the extent of fluorescence quenching (where present) and the initial rate of change in quenching were dependent on the concentration of phosphate added to cell suspensions and on the degree of limitation (growth rate in continuous culture). The addition of phosphate also brought about a transient decrease in photosynthetic oxygen evolution and a stimulation in respiration, which were relaxed as the added phosphate was depleted from the external medium. The applicability of using nutrient‐induced fluorescence transients as a tool to identify the nutrient status of phytoplankton populations is discussed. |
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Keywords: | chlorophyll fluorescence nutrient limitation phosphorus photosynthesis |
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