METHODS OF EXPERIMENTATION WITH COCKLEBUR 



85 



6-0- 



4-0-- 



< 

 q: 

 O 



H 2-0 



xo 

 o 



Control 



Maleic hydrozide 



^T— t-i 





Yellowing of young leaves 



Retarded leaf expansion — 

 Bulbils on edges of young leaves 



Tizz^^m 



Formative effects 



I 



^^///^ 



Moles/L MALEIC HYDRAZIDE 



10" 



10^ 



(MH-30 diethanolamine salt) 



Figure 5-7 

 An example of an experiment in which chemicals are applied to plants 

 in a logarithmic concentration series just before an inductive dark 

 period. The control is expressed as a line or level, since there is no zero 

 point on a logarithmic scale. Damage noted after 9 days is expressed by 

 relative width of the wedge-shaped bars. The exact concentrations for 

 this series are shown in Table 5-2. Floral Stages are explained near the 

 end of this chapter. See F. B. Salisbury, 1957, Plant Physiol 32, 600-608. 



methods which should be used only when simpler ones fail. Since 

 we know nothing about the concentration of a compound at its site 

 of action inside of the cells, the concentrations given in descriptions 

 of experiments must be considered in a relative sense and in light of 

 the experimental procedures which were used. 



4. Other Methods and Techniques 



The methods described above are not a complete summary of those 

 used in flowering studies. Since we are not going to consider vernali- 

 zation in the remaining part of the book, methods relating to this 

 problem are not mentioned here. Furthermore, the investigator will 

 often devise special procedures to suit the particular problems at hand. 



Grafting of one plant to another has been widely applied in 

 translocation studies. One method is the approach graft. It is 

 probably the simplest procedure which can be used to demonstrate 



