Which of these is not a function of the gaseous hormone ?

Options

A. Initiation of flowering and synchronization of fruit - set in pineapples
B. Promotion of male flowers in cucumbers thereby increasing its yield
C. Breaking the bud dormancy and promoting sprouting of potato tubers
D. Promotion of root growth and root hair formation, thus helping the the plants to increase their absorption surface.

Answer

To solve the question "Which of these is not a function of the gaseous hormone?", we will analyze the functions associated with ethylene, the gaseous hormone in plants.

### Step-by-Step Solution:

1. **Identify the Gaseous Hormone**: The gaseous hormone in question is ethylene. Ethylene is known for its role in various plant processes.

2. **Review the Functions of Ethylene**:
- **Initiation of Flowering and Synchronization of Fruit Set in Pineapples**: Ethylene is known to initiate flowering and synchronize fruit set, particularly in pineapples. This function is true.
- **Promotion of Male Flowers in Cucumbers**: Ethylene is actually known to promote female flowers in cucumbers, not male flowers. This function is incorrect.
- **Breaking Bud Dormancy and Promoting Sprouting of Potato Tubers**: Ethylene does help in breaking dormancy and promoting sprouting in tubers like potatoes. This function is true.
- **Promotion of Root Growth and Root Hair Formation**: Ethylene is involved in root growth, but it does not primarily promote root hair formation. This function is somewhat misleading but can be considered true in a broader context.

3. **Determine the Incorrect Function**: From the analysis, the second option, which states that ethylene promotes male flowers in cucumbers, is incorrect.

4. **Conclusion**: The answer to the question is that the function that is not associated with the gaseous hormone (ethylene) is the promotion of male flowers in cucumbers.

### Final Answer:
The correct answer is: **Promotion of male flowers in cucumbers thereby increasing its yield.**