Introduction
Plant growth regulation refers to the complex network of internal and external signals that coordinate plant development—from seed germination to flowering and senescence. These processes are primarily governed by plant hormones and influenced by environmental cues such as light, temperature, and water availability.
Key Plant Hormones
The major classes of plant growth regulators include:
- Auxins: Promote cell elongation and root formation.
- Gibberellins: Stimulate stem elongation, seed germination, and flowering.
- Cytokinins: Encourage cell division and delay leaf senescence.
- Abscisic Acid (ABA): Inhibits growth and promotes dormancy under stress conditions.
- Ethylene: Regulates fruit ripening, leaf abscission, and stress responses.
Environmental Influences
External factors significantly modulate hormonal activity:
- Light (photoperiod and quality) affects photomorphogenesis via phytochromes.
- Gravity guides root and shoot orientation (gravitropism).
- Water and nutrient availability alter hormone balance to adapt growth strategies.
Applications in Agriculture
Understanding plant growth regulation enables advances in crop yield, stress tolerance, and controlled flowering. Synthetic analogs of natural hormones are widely used in horticulture and farming to manage plant architecture, fruit set, and post-harvest shelf life.