Plant Hormones: Their nature occurrence and functions: A chapter
RK Yadav, Pradip Kumar Saini
Plant hormones are a class of organic substances which are synthesized during the plant metabolism. They have an obvious physiological effect on plant growth at very low concentrations. Generally, plant hormones are mainly divided into five categories: Auxins, Gibberellins (GAs), Cytokinins, Ethylene, and Abscisic acid (ABA). With the deepening of research, some novel plant hormones such as Brassinosteroid, Salicylates, Jasmonates, Polyamines, and Signal Peptides have been found and identified. The plant hormone products are mainly obtained through plant extraction, chemical synthesis as well as microbial fermentation.