Which hormone is mainly responsible for stem elongation in plants?

Gibberellin is primarily responsible for stem elongation in plants because it promotes cell elongation and division, which leads to increased internode length. This hormone, produced in young leaves and developing seeds, plays a crucial role in various growth processes, including seed germination and flowering. Gibberellins work by breaking dormancy in seeds and encouraging the growth of stems and leaves, enabling plants to reach light and space for enhanced survival and reproduction. The overall effect of gibberellin is to create the characteristic tall stature in plants that are favorable for photosynthesis and optimal resource acquisition.

In contrast, while cytokinin also influences growth and cell division, it primarily promotes lateral growth and leaf expansion rather than elongation. Ethylene, a gaseous hormone, is more involved in fruit ripening and response to stress rather than direct enhancement of stem height. Auxin contributes to cell elongation but works more significantly in coordination with gibberellin for elongation processes. Consequently, the distinct role of gibberellin makes it the primary hormone driving stem elongation.