MAXIMUM QUANTUM YIELD IN RELATION TO LIGHT CURVES 



1135 



Whenever this is the case, and equation (29.6) is obeyed, differentiation 

 with respect to / shows that the quantum requirement, I/7, is a linear 

 function of light intensity, with i/p™'"^"- as the slope : 



(29.7) 



1/7 = 1/70 + (I/P^-) 



The question arises whether the experimental value of I/7 is a linear 

 function of the intensity of irradiation and, if so, whether the slope of the 

 corresponding straight line is equal to the inverse of the saturation value 

 of photosynthesis in strong light, 1/P"'^^- 



7 - 



Emerson and Lewis (1941) 



Warburg (1948) 



02 0.4 06 0.8 



/, einstein/mole Chi x mm. 



1.0 



Fig. 29.8. Quantum requirement of Chiorella as function of light intensity. 



Figure 29.8 represents an attempt to apply equation (29.7) to the 

 quantum yield data of Emerson and Lewis (1943) and of Warburg (1948). 

 Warburg's values scatter too widely to decide whether they lie on a straight 

 line or not; but, if this is assumed to be the case, the slope of the straight 

 line is much higher than in the case of Emerson's measurements (indicating 

 a much more rapid decline of quantum yield with the intensity of illumina- 



