Growth hormones in plants, also known as phytohormones or plant growth regulators, act as chemical messengers that promote growth and development throughout the plant's tissues.
These hormones influence a wide array of processes, including:
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Cell Elongation and Division: Promoting cell elongation results in stem and root growth, while cell division contributes to overall plant mass.
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Differentiation: Guiding cells to specialize into specific tissues and organs (e.g., leaves, flowers, roots).
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Apical Dominance: Controlling the growth of the main stem relative to lateral buds. This often suppresses the growth of side branches, allowing the plant to grow taller.
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Tropic Responses: Mediating plant responses to environmental stimuli like light (phototropism) and gravity (gravitropism). This enables plants to orient themselves for optimal resource capture.
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Fruit Development: Playing a critical role in fruit set, growth, and ripening.
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Senescence: Regulating the aging process and leaf abscission (shedding).
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Seed Germination: Breaking seed dormancy and initiating seedling growth.
Examples of Plant Growth Hormones and Their Functions:
| Hormone | Primary Function(s) |
|---|---|
| Auxins | Cell elongation, apical dominance, root formation, fruit development |
| Gibberellins | Stem elongation, seed germination, flowering, fruit size |
| Cytokinins | Cell division, delay senescence, promote shoot growth |
| Abscisic Acid | Seed dormancy, stress response (e.g., drought tolerance), stomatal closure |
| Ethylene | Fruit ripening, senescence, abscission, response to stress |
In short, plant growth hormones coordinate and regulate a wide variety of developmental processes, allowing plants to adapt to their environment and optimize their growth and reproduction.
