
TY  - JOUR
A1  - Runcie, John W. 
A1  - Riddle, Martin J. 
T1  - <emph type="2">Research Note</emph>: Measuring variability in chlorophyll-fluorescence-derived photosynthetic parameters <emph type="2">in situ</emph> with a programmable multi-channel fluorometer
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2004
VL  - 31
IS  - 5
SP  - 559
EP  - 562
KW  - Antarctic, in situ, macroalgae, PAM, quantum yield, rapid light curve.
UR  - https://doi.org/10.1071/FP03213 
N2  - A submersible device was constructed for simultaneous in situ measurement of the effective quantum yield of chlorophyll fluorescence (&#916;F / Fm&#8242;) of eight macroalgal samples. The device incorporated a commercially available PAM fluorometer. Four samples each of the macroalgae Iridaea mawsonii (Lucas) and Monostroma hariotii (Gain) were examined. &#916;F / Fm&#8242; and light-response curves (LCs) were regularly applied over 24 h to estimate diel changes in relative electron transport rates and the relative efficiency of photon conversion at low irradiances (&#945;), and the variance attributable to mean values of both &#916;F / Fm&#8242; and &#945; were estimated. A second commercial single-channel fluorometer provided an independent measure of variability in LC parameters between individual samples, and the magnitude of this variability was within the range measured with the multi-channel device. Between-sample variability at noon, measured with the multi-channel device, was significantly greater than at other times of the day. &#916;F / Fm&#8242; of M. hariotii were not significantly different throughout most of the day except at midnight, when values were significantly higher. In contrast, over 24-h only &#916;F / Fm&#8242; of I. mawsonii at noon (growing in low light) was significantly lower. By providing replicate LCs at each time point, the programmable multi-channel fluorometer enables testing of significant differences in photosynthetic parameters over a diel period. 
ER  -

