88 • Floral Hormones and the Induced State 



induced by vernalization covered in the preceding chapter. Perhaps 

 j is most remarkable property, :ikin to the way in which a small Leaf 

 area brings about flowering in a large plant, is the way in which only 

 .1 small portion (the meristem) need be vernalized. Present evidence, 

 however, does not point to the existence <>i a transmissible stimulus, 



.ind the vernalized State probably occurs only in tissues actually 



derived from the cells originally treated. lake photoperiodic in- 

 duction, the effect <>l cold treatment is quantitative and "fra< tional" 

 undei < ertain < onditions. 



THE BIOCHEMISTRY ()!• INDUCTION 



Whit oi the cellular and biochemical changes involved in 

 induction and the final (lowering response? These changes must 



be understood il knowledge ol (he physiology <>l flowering is to be 

 more than supei Ik ial, but up to the present time very little evidence 

 sufficient to answer the question has been un<o\eied. The subject 

 cannot be dismissed so briefly, however, il only because many 

 investigators have tried to remedy the situation and one should be 

 awaie ol their attempts. 



As indicated in Chapters Two and Three, photoperiodic 



induction is a highly complex process. In SDP, at least, it is often 

 regarded as comprising several steps, or "partial processes"-— the 



lust high intensity light pioeess, the dark process, the low intensity 

 light process by which the dark process can be inhibited, and the 

 second high intensity light process. To these can also be added 



Horigen synthesis (marking the attainment of the induced state), 



followed by Horigen translocation, and then the changes in the 

 iiiciistcin (see, lor example. Bonner, 1959a; Bonner and Liverman, 



1953; Liverman, l!). r >r>). This analysis is more appropriate lor some 



plants than lot others, and none has been studied enough to 

 disclose- the iiatuie ol ,mv ol the partial pioc esses, except perhaps 



the two involving high light-intensity. These may be photosyntheti< . 



.is we have seen in Chapter Two. and thus supply both energy lot 

 the othci changes .ind c .u bohvclrales with which the Horigen moves. 



LDP have been less amenable t<> such an analysis, particularly with 

 the evidence ol both promoting and inhibiting actions clue to the 



leaves .ind both ol which may be- affected by light and darkness. 

 One ol the lew consistent observations is that the dark (and low 



