Trace organic substances produced by plants themselves and transported to other parts can regulate the growth and development of plants, which are called phytohormones. Synthetic substances with phytohormone activity are called plant growth regulators. There are five known plant hormones: auxin, gibberellin, cytokinin, abscisic acid and ethylene. Brassinosterol is gradually considered as the sixth kind of plant hormone.
The chemical structure of plant hormones has been known, and synthetic similar substances are called growth regulators, such as indoleacetic acid; Some can't be synthesized artificially, such as gibberellin. Gibberellin reagents sold in the market are made from the culture filtrate of Gibberella.
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Also called morphogenesis, it has a more obvious effect on inhibiting growth and germination. It can dwarf plants, destroy apical dominance, promote flower bud differentiation, promote abscission formation and inhibit gibberellin synthesis in plants.
The regulation of plant hormones on growth and physiological processes is often not the only function of a certain plant hormone. Because various endogenous hormones in plants can have synergistic or antagonistic effects, only the coordination of various hormones can ensure the normal growth and development of plants.