Studies on plant growth‐regulating substances. XXX. The plant growth‐regulating activity of substituted phenols

Publisher Website
Google Scholar
Abstract
SUMMARY: The growth‐regulating activity of a number of substituted monophenols and related compounds has been assessed in the wheat cylinder, pea segment, pea curvature and tomato‐leaf epinasty tests and the effect on activity of position, size and electronic nature of the substituents has been studied. The results indicate that, for high auxin activity, electron‐attracting substituents, having certain steric properties must be substituted in the 2‐ and 6‐positions. Furthermore, at least one of these ortho‐substituents must be capable of intramolecular bonding with the hydrogen of the phenolic hydroxyl group. Any substituent in the para‐position to the hydroxyl group leads to complete loss of activity and activity is reduced by meta‐substitution.This new group of phenolic plant growth regulators is considered in relation to other synthetic auxins from the viewpoints of structural requirements for activity and current theories on mode of action.