ABSTRACT
Plant hormones are naturally occurring substances that control growth and development. They are also known as growth substances. Plant hormones or phytohormones have been defined as “organic substances produced naturally in the higher plants, controlling growth or other physiological function at a site remote from its place of production and active in very minute amounts”. Plant bioregulators or plant growth regulators are defined as “organic compounds other than nutrients which in small amount promote/inhibit or otherwise modify any physiological response in plants” (Prasad and Kumar, 1999). Hormones usually move within the plant from the site of production to the site of action. There are five classes of phytohormones, namely auxins, gibberellins, cytokinins, ethylene and abscisins.
