Which hormone is primarily responsible for promoting plant growth?

The hormone that is primarily responsible for promoting plant growth is auxin. Auxins play a crucial role in various aspects of plant development, particularly in cell elongation, which leads to increased growth. They are involved in directing growth patterns in response to light (phototropism) and gravity (gravitropism), facilitating optimal sunlight exposure for photosynthesis and stability.

Auxins influence root formation, promote stem elongation, and are vital in the processes of apical dominance and the development of lateral buds. By causing cells on one side of a plant to elongate more than those on the other side, auxins enable plants to grow towards light sources, enhancing their ability to thrive.

While other hormones, such as gibberellins and cytokinins, also promote growth, they serve more specific roles; for example, gibberellins are involved in seed germination and stem elongation, and cytokinins promote cell division and shoot formation. Ethylene, on the other hand, is involved in processes such as fruit ripening and senescence, which are more about aging and maturation rather than growth promotion.