EFFECTS OF GIBBERELLIC ACID, KINETIN, AND 

 LIGHT ON THE GERMINATION OF LETTUCE SEED 



ALAN H. HABER and N. E. TOLBERT i 

 Biology Division, Oak Ridge National Laboratory,- Oak Ridge, 



Tennessee 



A reversible red, far-red photoreaction can profoundly affect many 

 aspects of plant morphogenesis (Wassink and Stolwijk, 1956). Here- 

 tofore, attempts to mimic the effects of red light by chemical treat- 

 ment achieved only slight success. Within the last few years, two groups 

 of chemicals, the gibberelHns (Stowe and Yamaki, 1957) and the 

 kinins (Skoog and Miller, 1957) have been shown to affect plant 

 development greatly and in some instances to produce changes similar 

 to effects of red light (Hillman, 1957; Kahn et al., 1957; Miller, 1956; 

 Scott and Liverman, 1957; Stowe and Yamaki, 1957). It has been 

 suggested that natural gibberellin-like (Phinney et al, 1957; Radley, 

 195^6; Stowe and Yamaki, 1957) and kinin-like (Danckwardt-Lillie- 

 strom, 1957; Skinner et al, 1957; Skoog and Miller, 1957) substances 

 occur in higher plants. It is thus conceivable that the red light effects 

 on some systems could be related to the production or activity of 

 endogenous gibberellin- or kinin-like substances. 



The effect of red light on the germination rate of Grand Rapids 

 lettuce seed can be mimicked by treatment with either gibberellin 

 (Kahn et al, 1957) or kinin (Miller, 1956; Skinner et al, 1957). 

 Moreover, promotion of germination by gibberellin or kinetin was 

 apparently not reversed by far-red light treatment (Kahn et al, 1957; 

 Miller, 1956). These results are consistent with hypotheses that the 

 photoreaction regulates levels of endogenous gibbereUin- or kinin-like 

 substances. 



In this paper it is demonstrated that gibberellic acid and kinetin 



1 Present address: Department of Agricultural Chemistry, Michigan State 

 University, East Lansing, Michigan. 



- Operated by Union Carbide Nuclear Company for the U. S. Atomic Energy 

 Commission. 



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