The most important plant hormone is auxin. Auxins are plant hormones that play a crucial role in a variety of plant processes, including growth and development, phototropism, gravitropism, apical dominance, and root development.
Auxins are produced in the apical meristem of plants and are transported downwards through the plant, where they regulate cell division and elongation. This hormone also promotes the growth of lateral buds and suppresses the growth of lower buds, allowing the plant to grow taller and compete for sunlight.
Additionally, auxin is responsible for phototropism, which is the plant's ability to bend towards light. This is particularly important for plants growing in shaded areas, as they need to bend towards light to maximize photosynthesis.
Overall, auxin is the most important plant hormone because it controls many vital aspects of plant growth and development, including cell division, elongation, phototropism, and lateral bud growth.