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Answer» Growth Promoters : Involved in growth promoting activities like-cell division, cell enlargement etc. Types of Growth Promoters : 1. Auxins 2. Gibberellins 3. Cytokinins| Name of Hormone | Physiological Effects | Application/Uses | 1. Auxin- first isolated from human urine.
- IAA, IBA are natural auxins isolated from plants.
- NAA, 2, 4-D are synthetic auxins.
| - Cause apical dominance.
- Prevent premature fall of leaves, flowers, fruits etc.
| - Initiate rooting in stem cuttings.
- Promote flowering in pineapple.
- Induce parthenocarpy in tomatoes.
- 2, 4-D used as weedicide.
| 2. Gibberellins :
All are acidic, hence also called Gibberellic acid. | - Bolting and flowering in rosette plants.
- Cause elongation of internodes.
- Break seed dormancy.
- Can elongate genetically dwarf plants
| - Increase the length of grape stalks.
- Delay senescence, hence fruit can be left on trees for longer period.
- Increases lengths of internodes in sugarcane, thereby increases yield.
| | 3. Cytokinins | - Cause growth of lateral buds and overcome apical dominance.
- Promote production of new leaves, and chloroplasts in leaves.
- Promote adventitious shoot formation
| Used to delay leaf senescence. |
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