GROWTH REGULATION BY ORGANIC COMPOUNDS

Abstract

Indoleacetic acid and 2,4-dichlorophenoxyacetic acid have equal growth activity as measured by the elongation of sections of Avena coleoptiles. Other halogen derivatives of phenoxyacetic acid have varying degrees of activity but those substituted in the 2,4 and 6 positions have no activity. Both phenoxyacetic acid and phenylacetic acid have little or no activity when methyl groups are substituted in the 2,4 and 6 positions. The growth activities of these compounds can be related to their chemical structure by the supposition that the position on the benzene ring adjacent to the point of attachment of the side chain is directly involved in the growth reaction.