Any substance that retards the growth of a plant or plant part. Almost any substance will inhibit growth if present at high enough concentrations but two common hormonal inhibitors are * abscisic acid and * ethylene , which both have effect at very low concentrations, similar to the effective concentrations of auxins, gibberellins, and cytokinins. Other inhibitors, which must be present in much higher concentrations to take effect, include certain of the phenolics, quinones, terpenes, fatty acids, and amino acids. |
