PHOTOMORPHOGENESIS 105 



Table III. Influence of Light Quality of a Main Light Period and of a Dark 



Interruption on Flowering (Duration of treatment, 16 tlays; condition of growing 



points 58 days after l)eginning of treatment) 



Main Light Period, Night Preal<, 10 min« 



10 hr/day Dark Control 10' Red 10' Green 10' Blue 



Salvia occidcnlalis (S.D. plant), 4 plants per treatment 



Red, 900 |uw/cm2 + + + + - + + + + + + + + + + + 



Green, 850 /iw/ cm- + + + + + + + + + + + + + + + + 



Blue, 950 Mw/cm^ + + + + + + + + 



Hyoscyamiis niger (L.D. plant), 3 plants per treatment 



Red, 900 Mw/cra^ 



Green, 850 ^tw/ cm- 



Blue, 950 /i\v/cm2 + + + +-f+ 



" Generative +; vegetative — . 



day followed by a supplementary irradiation of 8 hr with red, green, 

 or blue. The results of this treatment are given in Table IV. By using 

 this type of treatment to obtain a long-day effect, it is obvious that 

 blue light is more effective than green or red in prolonging a short 

 day. This behavior of Salvia is similar to that of the Cruciferae 

 (Funke, 1948; Wassink ^^ a/., 1956). 



In Stolwijk's experiments the filters transmitted not only the blue 

 light but also a small amount of infrared, and for this reason it might 

 appear that the blue light effect in his experiments could be due to 



Table IV. Influence of Light Quality of a Supplementary' Irradiation of 8 hr after 

 a Short Day (8 hr) in White Light (2100 fJLw/cm^) on Flowering of Salvia occidentalis 



(S.D. plant)" 



Spectral Region Red Green Blue Dark Control 



Light intensity, fxw/cm' 



' + 



50 



65 + 



85 + 



250 



325 - 



415 + 



500 



650 - 



830 + 



« Generative + ; vegetative — . 



