What are the classifications of cytokinins?

Natural cytokinins include:
Kinetin (KT):
Isolated from herring sperm cells in 1955, it was the first naturally discovered cytokinin.

Zeatin (ZT):
Isolated from immature maize seeds, it stimulates cell division, promotes chlorophyll formation, accelerates metabolism, and protein synthesis.

Dihydrozein (DHZ):
Similar to zein, it is also a natural cytokinin.
Isopentyladenine (iP) and isopentenyladenine (iPA):There are also more than thirty other natural analogs.

Commonly used synthetic cytokinins include:
6-Benzylaminopurine (6-BA):
Synthesized in 1952, it is widely used in agricultural crops, promoting bud formation and inducing callus formation.

Forchlorfenuron (CPPU):
Synthesized in 1979, it was widely used in agricultural production in the 1980s and possesses strong cell division activity.

Thidiazuron:
First synthesized by a German company in 1976, it promotes cell division, induces callus formation, and accelerates fruit enlargement and ripening.

The above information summarizes the main types and characteristics of natural and synthetic cytokinins.