Final answer:
The plant growth hormone auxin, specifically IAA, is widely used to promote plant growth, particularly for root development in cuttings. Gibberellin is another growth hormone that stimulates shoot elongation and seed germination. Lastly, cytokinins are important in promoting cell division and delaying leaf aging.
Step-by-step explanation:
The plant growth hormone that can be utilized to enhance the speed of plant growth is auxin. Auxin, particularly IAA (Indole-3-acetic acid), is used in various agricultural and horticultural applications. It promotes the growth of adventitious roots on cuttings and detached leaves, aiding in successful plant propagation. Moreover, synthetic auxins are applied to greenhouse tomato plants to encourage normal fruit development and to synchronize fruit setting and dropping, making the harvesting season more efficient.
Another important growth hormone for plants is gibberellin (GA). Gibberellins are responsible for stimulating shoot elongation, seed germination, and the maturation of fruits and flowers. Gibberellins are produced in various parts of the plant, including root and stem apical meristems, young leaves, and seed embryos. Applications of GA can be important in urban settings where, for example, GA antagonists are used to control the growth of trees beneath power lines.
Cytokinins are also vital for plant growth, particularly known for promoting cell division (cytokinesis), and are found in abundance in growing tissues. They not only promote growth but also have a role in delaying senescence (aging) in leaf tissues and stimulating differentiation in shoots and roots.