Auxin
First plant hormone discovered by Charles & Francis Darwin (1881) while studying phototropism (bending of stems to light)
Produced in apical part of shoot (and root) (F. Went, 1926)
Promotes
- growth and elongation by increased cell division
- initiation of root growth
- vascular activity, fruit development
- growth of pollen tube
Inhibits leave abscission
Pollination can induce auxin production ? fruit development
Synthetic auxins: prevent fruit drop; promote flowering & fruiting (pineapple);root formation in cuttings;weed-killers in lawn formulas