Which of the following breaks the dormancy of seeds?A IAA B GA C Ethylene D All of the above

To determine which option breaks the dormancy of seeds, we need to analyze the role of the listed substances in seed germination.

1. IAA (Indole-3-acetic acid): A type of auxin that can promote growth but is not primarily known for breaking seed dormancy.

2. GA (Gibberellic Acid): This is a gibberellin that is well-documented to break seed dormancy and stimulate germination by promoting α-amylase production, which helps mobilize stored food in the seed.

3. Ethylene: This gas can also play a role in breaking dormancy in some seeds by promoting germination under specific conditions, although its primary role is in fruit ripening.

4. All of the above: Given that both GA and ethylene can break dormancy in various seeds, while IAA has a lesser effect, it could be reasonable to consider all as contributing agents depending on the seed type.

Final Answer

The correct option is D: All of the above, as IAA, GA, and ethylene can all play roles in breaking seed dormancy, although their effectiveness varies among different species.