98 



P. F. Wareing and T. A. ViUiers 



18 



10 



0.4 



0.8 





 Rf 



0.4 



0.8 



Fig. 2. Aqueous extract of F. excelsior seeds assayed by the Avena. coleoptile test. 

 A — extract of dry seeds; B — extract of seeds imbibed for 48 hrs. Solid horizontal 

 line indicates water control. (Running solvent as for Figure 1.) 



Rf values, but aqueous extracts of the dry seed contain no inhibitors. 

 If, however, the seed is allowed to imbibe water at laboratory tem- 

 peratures for 24 hrs. or more, then an inhibitory region appears on 

 the chromatograms at Rf 0.7 to 0.9 (Figure 2). Evidently this inhib- 

 itor is metabolically produced, since it does not appear during moist 

 storage at 0° C. This inhibitor, which is water soluble and ether in- 

 soluble, not only inhibits Avena coleoptile sections, but also cress 

 roots, lettuce seeds, and embryos of F. excelsior (Figure 3). On ger- 

 mination the level of this water-soluble inhibitor appears to be de- 

 pressed slightly and an ether-soluble inhibitor of the same R,- as the 

 (^-inhibitor of other workers appears. 



The presence of this growth inhibitor raises two questions, viz. 



(1) Does the inhibitor play any significant role in the dormancy of 



the seed? (2) Does chilling-treatment remove the dormancy by bring- 



t- z 



o — 



z 



-1 UJ 



Q. 



o 



UJ 



_l 

 o 

 o 



14 



12 - 



04 



08 



04 



0.8 



Rf 



6 I 



o 



z 



- 4 



Z UJ 



- _l 

 o 



UJ Q 



O) < 



< cc 



UJ 



cc 



o u. 



z o 



Fig. 3. Assay of a<iucc)us extract of embryos of F. excelsior. Chromatograni halved 

 longitudinally, A assayed with Avena coleoptile test, B assayed with leached F. ex- 

 celsior embryos. Solid horizontal line indicates water control. (Ruiuiing solvent 

 as for Figure 1 .) 



