540 M. Kh. Chailakhian 



reduced etiolated leaves. Addition of GA and kinetin to the medium 

 led to complete inhibition of root formation and, as a result, to slow- 

 ing down of shoot growth. In all experiments, excluding those with 

 kinetin, differentiation of flower buds on the tips of the etiolated 

 shoots was observed 25 to 30 days after planting. 



Plant growth was more intense under long-day than under short- 

 day conditions. The growth was somewhat weaker in the heteroauxin, 

 adenine, and kinetin experiments and especially in the GA exper- 

 iments. Differentiation of flower buds under long-day conditions 

 occurred only in experiments in which adenine and kinetin were 

 added 25 to 30 days after planting. With growth of the differentiated 

 buds they became distinctly visible. 



The data obtained show that when adenine and kinetin are in- 

 troduced into the medium, Perilla plants grown from isolated buds 

 under long-day conditions form flower buds. This permits one to 

 suggest that nucleic acid metabolism as a whole, and some derivatives 

 of this metabolism, are related to processes responsible for the initi- 

 ation of flower organs in short-day species. 



The experimental data presented here do not, of course, solve the 

 problem of elucidating the nature of the flowering hormones. Never- 

 theless, it seems to us that they confirm the main idea that flowering 

 of very different types of plants is the result of interaction of two 

 groups of substances which compose florigen, or the flowering hor- 

 mone complex, which is the same for all plants. 



SUMMARY 



The elucidation of the problem on the interrelation between 

 gibbcrellins and florigen led to the idea that flowering hormones 

 common to all plants (florigen complex) consist of two groups of 

 substances: gibbcrellins, necessary for stem formation and growth, 

 and anthcsins, required for flower formation. 



This idea finds sujjport in the induction of flowering in a long- 

 day species, Rudbeckia, under short-day conditions by means of gib- 

 berellin-like substances. These latter are present in acetone extracts 

 from the leaves of short-day species, 'Mammoth' tobacco, which vege- 

 tates under long-day conditions. Another proof is given by the in- 

 duction of flower bud formation in plants of a short-day species, red 

 Perilla, reared from isolated tops under long-day conditions mider 

 the effect of atlenine and kinetin. 



These data prove the idea that flowering of various plants is a 

 result of the interaction of two groups of sidistances which comprise 

 the flowering hormone complex, which is the same for all plants. 



