127 



J. L. Rosenberg and Tevfik Bigat 



GREEN PLANTS 



We report here two experiments with green plants which bear on 

 the problem of interaction between the two photochemical systems. 

 By a procedxare described in detail elsewhere^ we determined the 

 fluorescence spectriim at the one-second peak of the induction 

 outb"urst following a dark period relative to the spectrum at 

 steady-state irradiation. Fig. 3 summarizes some typical results, 



o 



I s 



> 



o 



« 



a: 



6- 



660 



680 700 720 740 

 Wove - length in mp. 



760 



Fig. 3- Relative fluorescence spectrum of a fresh 

 Forsyi:hia leaf at the induction maximum. The leaf was 

 illuminated in air with blue-green light, I = 800 x 10--'--'- 

 einstein/cm^-sec, following a 10-minute dark period. 

 R^ is intensity of emission at wave-length \ at the 

 steady-state, reached after about 20 seconds of 

 irradiation. The abscissa, measuring the ratio of 

 R^y^ to R^YQ (^si'^g 679 W- a.s a reference wave-length), 

 would follow the dashed horizontal line If the induction 

 outburst had the same spectrum as the steady- state 

 fluorescence. The two curves' are for different samples . v-'-'^'' 



The c\arves of Fig. 3 show that there is relatively more 

 increase in 679 n^M' fluorescence (the main chlorophyll a band) 

 d\aring the outbxorst than in the longer wave-length component. 

 The same was found for many kinds of samples, both leaves and 



