| Hormone Group | Primary Functions | Key Application / Effect |
| Auxins (e.g., IAA) – The “Stretcher” | Promotes growth toward light (phototropism) and downward (geotropism). | Used in rooting powders to help plant cuttings grow roots quickly. |
| Gibberellins (GA) – The “Jack-up” | Breaks seed dormancy and promotes rapid “bolting” or stem stretching. | Used to increase the size of seedless grapes and improve malt production in brewing. |
| Cytokinins – The “Multiplier” | Promotes cytokinesis and delays the aging (senescence) of leaves. | Used to keep cut flowers fresh longer and promote “bushy” growth in crops. |
| Abscisic Acid (ABA) – The “Brake” | Known as the “stress hormone.” It closes stomata during drought and maintains dormancy. | Acts as the “internal brake,” preventing seeds from sprouting in the middle of winter. |
| Ethylene (Gas) – The “Ripener” | Triggers fruit ripening and the shedding of leaves and flowers. | Used commercially to ripen tomatoes and bananas after shipment. |
Phytohormones: Quick Reference Guide
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