534 



M. Kh. Chailakhian 



end of the experiments the control phints remained in tlie rosette 

 stage. Two o£ the experimental plants that were treated with an ex- 

 tract from the leaves of long-day 'Mammoth' tobacco developed at an 

 especially high rate, and one of them budded and flowered almost at 

 the same time as the plants treated with gibberellin. The plant 

 treated with an extract from the short-day 'Mammoth' tobacco de- 

 veloped more slowly (Figure 2). 



Later, growth of the stems of plants treated with an extract from 

 long-day 'Mammoth' tobacco was cjuite intense, and at the end of 

 April many flowers had formed on the thick stem of one of the 

 plants. The stem of the plant treated with a short-day 'Mammoth' 

 tobacco extract was also thick, but much shorter, and had only one 

 terminal flower (Figure 3). 



Two plants treated with an extract from leaves of long-day Perilla 

 only at the end of April formed small buds on short shoots and did 

 not flower. Plants treated with short-day Perilla extracts did not bud 

 at all. A plant treated with an extract from long-day Rudbeckia bud- 

 ded and began to flower earlier than that treated with an extract 

 from the leaves of short-day Rudbeckia (Figure 4). 



Fig. 2. Effect of extracts from 'Mammoth' tobacco leaves on ilic growth of 

 Rudbeckia. A, 0.02 per cent GA; B, extracts from lca\cs of Imig-dav phints: C, c\- 

 trnrt from leaves of sliort-day plants; D, control, water. 



