Table : table 36.2 Plant Growth Hormones
| Hormone | Structure | Typical activities |
|---|---|---|
| Abscisic acid* |  | Maintains seed dormancy; closes stomata |
| Auxins (mainly indol |  | Promote stem elongation, adventitious root initiation, and fruit growth; inhibit axillary bud outgrowth, leaf abscission, and root elongation |
| Brassinosteroids |  | Promote stem and pollen tube elongation; promote vascular tissue differentiation |
| Cytokinins |  | Inhibit leaf senescence; promote cell division and axillary bud outgrowth; affect root growth |
| Ethylene |  | Promotes fruit ripening, leaf abscission, and senescence; inhibits stem elongation and gravitropism |
| Gibberellins (e.g., gibberellic acid) |  | Promote seed germination, stem growth, and ovule and fruit development; break winter dormancy; mobilize nutrient reserves in grass seeds |
*See Chapter 37. | ||