Which plant hormone is responsible for promoting seed germination?

Gibberellin is the key plant hormone responsible for promoting seed germination. This hormone plays a significant role in breaking seed dormancy and initiating the germination process. It activates enzymes that are essential for the metabolism of stored food reserves within the seed, such as amylase, which helps convert starches into sugars that the emerging seedling can utilize for energy. Additionally, gibberellins promote stem elongation, ensuring that the seedling can quickly break through the soil surface to access light.

Auxins, while influential in various growth processes, primarily regulate cell elongation and differentiation, and are more associated with the growth responses of stems and roots rather than directly promoting germination. Cytokinins mainly stimulate cell division and promote shoot formation and lateral branching. Ethylene is more commonly known for its role in fruit ripening and the regulation of specific developmental processes, rather than initiating germination. Thus, gibberellin stands out as the primary hormone that drives and supports the germination of seeds.