What are plant growth regulators?
Chemical messengers that regulate growth and metabolic activities in plants
They influence physiological processes such as cell division, elongation, dormancy, flowering, and senescence.
Name the five major groups of plant growth regulators.
- Auxins
- Cytokinins
- Gibberellins
- Abscisic acid (ABA)
- Ethylene
What is the nature of Auxins?
Indole acetic acid (IAA) or its variants
What is one function of Auxins in stems?
Promote cell enlargement behind the apex and cell division in the cambium
How do Auxins affect roots at low and high concentrations?
Promote growth at low concentrations, inhibit growth at high concentrations
What is apical dominance in relation to Auxins?
Promote apical dominance and fruit growth, can induce parthenocarpy
What effect do Auxins have on leaf senescence?
Delay leaf senescence in some species
What is the nature of Gibberellins?
Produced in the apical portions of roots and shoots, containing Gibberellic acid
One function of Gibberellins is to promote _______ in rosette plants.
bolting
How do Gibberellins influence dormancy?
Break bud and seed dormancy
What is one role of Gibberellins in flowering?
Promote flowering in long-day plants, inhibit flowering in short-day plants
What is the nature of Cytokinins?
Produced in roots, young fruits, and seeds
What is a primary function of Cytokinins?
Promote cytokinesis (cell division)
What do Cytokinins do to primary and lateral root growth?
Inhibit primary root growth, promote lateral root growth
Cytokinins can promote _______ in leaves.
leaf growth
What is the nature of Abscisic Acid (ABA)?
Synthesized mainly in mature green leaves, fruits, and root caps
What effect does Abscisic Acid have during physiological stress?
Inhibits stem and root growth
What role does Abscisic Acid play in dormancy?
Promotes bud and seed dormancy
True or False: Abscisic Acid promotes flowering in long-day plants.
False
What does Abscisic Acid promote in relation to leaf senescence?
Sometimes promotes leaf senescence
What process does Abscisic Acid promote related to shedding?
Promotes abscission (shedding of leaves or fruits)
