Plant hormones and growth regulators play crucial roles in regulating plant growth, development, and responses to environmental stimuli. Understanding these hormones is essential for NEET aspirants.
Major Plant Hormones
1. Auxins:
- Functions: Promote cell elongation, root initiation, and differentiation. Involved in phototropism and gravitropism.
- Example: Indole-3-acetic acid (IAA).
- Applications: Used in rooting powders and herbicides.
2. Gibberellins:
- Functions: Stimulate stem elongation, seed germination, and flowering. Break seed dormancy.
- Example: Gibberellic acid (GA3).
- Applications: Used to enhance fruit size and delay aging in plants.
3. Cytokinins:
- Functions: Promote cell division, delay leaf senescence, and stimulate shoot formation.
- Example: Zeatin.
- Applications: Used in tissue culture and to prolong the shelf life of vegetables.
4. Ethylene:
- Functions: Regulates fruit ripening, leaf abscission, and response to stress.
- Example: Ethylene gas (C2H4).
- Applications: Used to ripen fruits like bananas and tomatoes.
5. Abscisic Acid (ABA):
- Functions: Induces seed dormancy, closes stomata during water stress, and inhibits growth.
- Example: Abscisic acid (ABA).
- Applications: Used to manage plant stress responses.
Growth Regulators
1. Brassinosteroids:
- Functions: Promote cell expansion and elongation, enhance resistance to stress, and improve overall plant growth.
- Example: Brassinolide.
- Applications: Used to enhance crop yields and improve stress tolerance.
2. Jasmonates:
- Functions: Involved in plant defense responses, seed germination, and root growth.
- Example: Jasmonic acid (JA).
- Applications: Used to enhance plant resistance to pests and diseases.
3. Salicylic Acid:
- Functions: Plays a role in plant defense mechanisms and response to pathogens.
- Example: Salicylic acid.
- Applications: Used to induce resistance in plants against pathogens.
Conclusion
Understanding plant hormones and growth regulators is crucial for NEET aspirants. These substances control various aspects of plant growth, development, and response to environmental conditions, making them essential topics in plant physiology.
FAQs
What is the role of auxins in plants? Auxins promote cell elongation, root initiation, and differentiation, and are involved in phototropism and gravitropism.
How do gibberellins affect plant growth? Gibberellins stimulate stem elongation, seed germination, and flowering, and help break seed dormancy.
What are the applications of cytokinins in agriculture? Cytokinins are used in tissue culture to stimulate shoot formation and to prolong the shelf life of vegetables.
What is the function of ethylene in plants? Ethylene regulates fruit ripening, leaf abscission, and response to stress.
How does abscisic acid help plants during water stress? Abscisic acid induces stomatal closure, reducing water loss during stress conditions.