AUXIN

Endosperm and embryo of seeds meristems of apical buds and young leaves.

stimulates stem elongation, root growth apical dominance, development of fruit ,instrumental in photrophism and gravitropism.

CYTOKININS

produced in roots and transportedto other organs

stimulates cell division and growth, seed germination, flowering , and delay senescence.

Meristems of apical buds, roots, and young leaves; embryo.

promotes seed and bud germination, stem elongation, leaf growth, stimulate flowering and development of fruit.

leaves, stems, green fruit

Inhibits growth, closes stoma during water stress; counteracts breaking of dormancy.

ETHYLENE

tissues of ripining fruits, nodes of stems, senescent

Promotes fruit ripening; opposes or reduces some auxins, inhibits growth of roots, leaves, flowers, depending on species.