BORJE ABERG 



Royal Agricultural College 

 Uppsala, Sweden 



Some New Aspects of the Growth 

 Regulating Effects of Phenoxy 



Compounds 



The present study utilized 79 phenoxy derivatives, all of which were 

 tested for their growth regulating effects on oat coleoptile cylin- 

 ders, wheat roots and flax roots following previous methods (4). 

 The data have been condensed in Table 1. Full details have been 

 given for some of the substances by Aberg (6) and will follow for the 

 others. In the present connection only the effects of certain especially 

 interesting substances or series of substances will be illustrated by 

 concentration-response curves and more detailed data for their inter- 

 action with other types of growth regulators. 



Among the substances studied, most of which have been kindly 

 supplied by Professor A. Fredga and Dr. M. Matell, are 17 pairs of 

 optically active a-propionic acids. In order to save space the follow- 

 ing basic abbreviations will be used: - POA: phenoxyacetic acid, 

 CoHr.OCHoCOOH; POP: a-(phenoxy)propionic acid; POB: a- 

 (phenoxy)-?z-butyric acid; POiB: a-(phenoxy)isobutyric acid; POV: a- 

 (phenoxy)-w-valeric acid; POiV: a-(phenoxy)isovaleric acid; POC: a- 

 (phenoxy)-n-caproic acid. Substituents of the phenyl ring will be indi- 

 cated in the usual manner; 2,4-dichlorophenoxyacetic acid will thus 

 be abbreviated 2,4-CloPOA (or shorter: 2,4-D). For the halogens the 

 chemical symbols (F, CI, Br, I) are used, but some other groups are 

 further abbreviated in the following manner: Me: methyl, Et: ethyl, 

 iP: isopropyl, tB: tert-huty\, -C(CH3)3, MeO: the methoxy group, 

 -OCH3, Ni: the nitro group, -NOo. 



The optical activity is usually indicated by the sign of rotation, 

 dextrorotatory forms by (+) and laevorotatory forms by (— ). The 

 (^)-forms generally belong to the d series, with one notable excep- 



[219] 



