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GROWTH FACTORS AND FLOWERING 



size capable of responding to photoinduction. The days from seeding 

 to appearance of the first visible flower buds were selected as the 

 criterion for measuring the modifying influence of gibberellin on 

 photoperiodic responses. 



Long-Day Plants 



Flowering was accelerated in facultative long-day plants (Brassica 

 jimcea Coss., Brassica pekinensis Skeels, and Centaurea cyanus 

 Linn.) grown under both long and short days (Table I and Fig. 1). 



Table I. Modifying Effects of Foliar Sprays of Gibberellin on the Photoperiodic 

 Responses of Several Facultative and Obligate Long-Day Plants 



" Days from seeding to appearance of visible flower buds. 



" Flowering in significantly fewer days than controls (P = 0.05). 



The most pronounced differences were, however, at the 9-hr photo- 

 period. Furthermore, the acceleration in time of flowering under both 

 day lengths was generally proportional to the amount (concentration) 

 of gibberellin sprayed on the foliage. 



Flowering in Chrysanthemum parthenium Pers. which had an 



