How do gibberellins affect plant growth?

Gibberellins are a class of plant hormones that play a crucial role in regulating various aspects of plant growth and development. One of the key functions of gibberellins is their effect on stem elongation and seed germination. They promote stem elongation by stimulating cell division and elongation, which leads to taller plants that can compete more effectively for sunlight. This elongation allows for more efficient photosynthesis, which is vital for the plant's overall growth.

During seed germination, gibberellins help initiate the process by breaking dormancy. They activate enzymes that mobilize stored nutrients within the seed, providing the necessary energy for growth as the seedling begins to emerge from the soil. This action is essential for ensuring that seeds can germinate when conditions are favorable.

In contrast, while other options like promoting leaf color changes, increasing flower size, and enhancing seed storage may affect overall plant health and reproduction, they are not primary actions associated with gibberellins. The most direct and noteworthy effects are indeed on stem elongation and seed germination, making the second choice the most accurate representation of gibberellin function in plant growth.