Short-Term Growth Response to Growth Regulators In Roots of Zea Mays

Abstract

A study was made of the inhibition of root growth in Z. mays by 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,6-trichlorophenoxyacetic acid (2,4,6·T), and indole-3-acetic acid (IAA) over a wide range of concentrations. IAA and 2,4·D caused identical responses whereas the response to 2,4,6-T was different. Application of 2,4.D or IAA at concentrations of 4·5xl0-4M for 5 min resulted in an immediate reversible inhibition of root growth whereas long-term application gave an irreversible inhibition. The same concentration of 2,4,6-T caused a similar degree of inhibition of root growth, but only after an extended treatment, and the roots could then recover from the inhibition in the presence of the chemical.