Gibberellin was discovered by Kurosawn in 1928. He observed that a rice. plant was infected by the fungus Gibberella. It showed excessive stein elongation. The symptom is called “Bakanae– disease. The fungus produces a substance .This substance caused this elongation. This substance was named


The special substances produced by the plants which influence the growth and plant responses are called plant hormones. Plant hormones are auxins, gibberellins, cytokinins, abscisic acid and ethylene. AUXINS The natural auxin is indole acetic acid (IAA). A large number of synthetic auxins are