348 GROWTH FACTORS AND FLOWERING 



have succeeded in opening the door into the biochemistry of flower 

 formation. However, we should not be utterly disappointed even if 

 this were true. Gibberellin is the first native material which is capable 

 of causing stem elongation and flower formation in at least numerous 

 representatives of two large physiological plant groups, the cold- 

 requiring and the long-day plants, under strict noninductive conditions. 

 It has also quite a number of other effects (on seed germination, cell 

 division, dormancy phenomena). It is thus a very powerful tool in 

 regulating various plant responses, and if used judiciously and criti- 

 cally it cannot but help us in furthering our understanding of plant 

 growth and development, including flower formation and its photo- 

 periodic control. 



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Bonner, J., and J. Thurlow. 1949. Inhibition of photoperiodic induction in 

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Borthwick, H. A., and M. W. Parker. 1940. Floral initiation in Biloxi soybeans 

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BiJnsow, R., and R. Harder. 1956a. BlUtenbildung von Bryophyllum durch 

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1957c. Bliitenbildung von Adonis und Rudbeckia durch Gibberellin. 



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 Cooke, A. R. 1954. Changes in free auxin content during the photoinduction 



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 von Denffer, D., and H, Griindler, 1950. Uber wuchsstoffinduzierte Bliih- 



hemmung bei Langtagpflanzen. Biol. Zentr., 69, 272-82. 

 von Denffer, D., and Liesellore Schlitt, 1951. Blijhforderung durch Ultra- 



violettbestrahlung. N aturwissenschaften, 38, 564-65. 

 Dostal, R., and M. Hosek. Ober den Einfluss von Heteroauxin auf die Mor- 



phogenese bei Circaea (das Sachssche Phanomen). Flora, 131 , 263-86. 

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control of elongation of Pinto beans and other plants under normal condi- 

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 Goodwin, R. H. 1937. The role of auxin in leaf development in Solidago 



species. Am. J. Botany, 24, 43-51. 

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COo metabolism and photoperiodism in Kalanchoe. Plant Physiol, 29, 220- 



29. 



