353 



David C. Fork 



chlorophyll a was the ultimate acceptor of phycobilin-absorbed 

 light, the idea arose that a certain fraction of red algal chloro- 

 phyll a must be photosynthetically inactive. In a study of inac- 

 tivity of chlorophyll in the far red (the so-called far-red de- 

 cline) Emerson and co-workers '^»°) found that lowered temperatures 

 extended the efficiency of photosynthesis to longer wavelengths, 

 both in Chlorella and in the red alga Porphvridium cruentum . 



ACTION SPECTRA FOR PHOTOSYNTHESIS OF RED ALGAE 

 AT LOW TEMPERATURES 



Since the action spectra determined by Haxo and Blinks ^^^ for 

 red algae were done at room temperature it was suggested that sim- 

 ilar measurements at lower temperatures might reveal a more active 

 chlorophyll. Action spectra given in figure 1 for red algae meas- 

 ured at 1° and 5° and again at 20 and 27° C were almost identical 



c 

 o 



o 



D 



o 



O 



c 

 o 



J3 

 O 



c 



0) 



o 



I. 



a 



~i 1 I I r 



Porphyra 

 perforata 



\o ooo^' 



600 700 



Wavelength, m;j 



400 500 600 700 



Wavelength, tnjj 



Fig. 1, Action spectra for O2 evolution in red algae 

 determined at different temperatures. Fork^^^. 



