What is Plant Growth Regulators?

Plant growth regulators, also known as plant hormones or phytohormones, are naturally occurring substances that regulate various physiological processes in plants. These regulators play a crucial role in controlling plant growth, development, and responses to environmental stimuli. They are produced in minute quantities by plants and are responsible for coordinating growth and development throughout the plant’s life cycle.

The Role of Plant Growth Regulators

Plant growth regulators have diverse functions and are involved in several important processes in plants. These include:

1. Cell Division and Elongation

Plant growth regulators such as auxins and cytokinins are involved in regulating cell division and elongation. Auxins promote cell elongation, while cytokinins stimulate cell division. These regulators work together to maintain the balance between cell division and elongation, ensuring proper growth and development of plant tissues.

2. Seed Germination

Plant growth regulators also play a crucial role in seed germination. Gibberellins, a class of plant hormones, promote seed germination by breaking seed dormancy and stimulating the synthesis of enzymes involved in the breakdown of stored nutrients in the seed.

3. Root and Shoot Growth

Auxins are primarily responsible for controlling root and shoot growth. They promote root development and inhibit shoot growth, ensuring a well-balanced growth pattern in plants. Additionally, gibberellins also play a role in shoot elongation.

4. Flowering and Fruit Development

Plant growth regulators are involved in the regulation of flowering and fruit development. Gibberellins and cytokinins promote flowering, while auxins and gibberellins are involved in fruit development. These regulators ensure proper timing and coordination of these processes.

5. Abscission

Plant growth regulators also regulate the process of abscission, which is the shedding of leaves, flowers, or fruits. Ethylene, a plant hormone, plays a significant role in promoting abscission by weakening the cell walls at the abscission zone.

6. Stress Responses

Plant growth regulators are involved in plant responses to various environmental stresses, such as drought, heat, cold, and pathogen attacks. They help plants adapt and survive under unfavorable conditions by regulating physiological and biochemical processes.

7. Senescence

Plant growth regulators also regulate the process of senescence, which is the aging and eventual death of plant tissues and organs. Ethylene plays a crucial role in promoting senescence by triggering the breakdown of chlorophyll and other cellular components.


In conclusion, plant growth regulators are essential for the proper growth, development, and responses of plants to their environment. They regulate various physiological processes, including cell division and elongation, seed germination, root and shoot growth, flowering and fruit development, abscission, stress responses, and senescence. Understanding the role of these regulators is crucial for optimizing plant growth and improving crop productivity.