Plant hormone – Definition & Detailed Explanation – Botanical Glossary

I. What are plant hormones?

Plant hormones, also known as phytohormones, are chemical messengers that regulate various physiological processes in plants. These hormones are produced in specific cells or tissues and are transported to other parts of the plant where they elicit specific responses. Plant hormones play a crucial role in growth, development, and response to environmental stimuli.

II. How do plant hormones function?

Plant hormones function by binding to specific receptors on target cells, triggering a cascade of biochemical reactions that lead to changes in gene expression and cellular processes. These hormones can either promote or inhibit growth, depending on the concentration and timing of their release. Plant hormones also interact with each other to coordinate complex developmental processes.

III. What are the different types of plant hormones?

There are five main types of plant hormones: auxins, gibberellins, cytokinins, abscisic acid, and ethylene. Each hormone has specific functions and effects on plant growth and development. Auxins promote cell elongation and root development, gibberellins stimulate stem elongation and seed germination, cytokinins promote cell division and delay senescence, abscisic acid regulates seed dormancy and stress responses, and ethylene regulates fruit ripening and senescence.

IV. How do plant hormones regulate plant growth and development?

Plant hormones regulate plant growth and development by controlling processes such as cell division, cell elongation, differentiation, and senescence. For example, auxins promote cell elongation in the stem, gibberellins stimulate seed germination and stem elongation, cytokinins promote cell division in the root, abscisic acid regulates seed dormancy, and ethylene triggers fruit ripening. These hormones work together to coordinate the growth and development of the plant in response to internal and external signals.

V. How are plant hormones used in agriculture?

Plant hormones are widely used in agriculture to regulate plant growth, improve crop yield, and enhance stress tolerance. Farmers use synthetic hormones to promote root development, increase fruit set, delay senescence, and improve crop quality. For example, auxins are used to promote root formation in cuttings, gibberellins are used to stimulate seed germination and fruit growth, cytokinins are used to delay senescence in fruits and flowers, abscisic acid is used to regulate water stress responses, and ethylene is used to ripen fruits artificially.

VI. What are some examples of plant hormones and their effects on plants?

One example of a plant hormone is auxin, which promotes cell elongation in the stem and root, regulates apical dominance, and stimulates root development. Another example is gibberellin, which stimulates stem elongation, seed germination, and fruit growth. Cytokinin is another plant hormone that promotes cell division, delays senescence, and regulates shoot growth. Abscisic acid is a hormone that regulates seed dormancy, stomatal closure, and stress responses. Ethylene is a hormone that triggers fruit ripening, leaf senescence, and abscission.

In conclusion, plant hormones play a crucial role in regulating plant growth and development. These chemical messengers coordinate various physiological processes in plants, such as cell division, elongation, differentiation, and senescence. By understanding the functions and effects of different plant hormones, farmers can use them to improve crop yield, enhance stress tolerance, and promote sustainable agriculture practices.