In which of the following condition, autogamy is prevented but not geitonogamy ?

Options

A. Self - incompatibility of pollen and stigma .
B. Non-synchronization of pollen and anther release .
C. Monoecious condition
D. Dioecious condition

Answer

To solve the question "In which of the following conditions, autogamy is prevented but not geitonogamy?", we need to understand the definitions and differences between autogamy and geitonogamy.

### Step-by-step Solution:

1. **Define Autogamy and Geitonogamy**:
- **Autogamy**: This is a type of self-pollination where pollen from the same flower fertilizes its own ovules.
- **Geitonogamy**: This is also a form of self-pollination, but it occurs between different flowers of the same plant.

2. **Identify the Conditions**:
- The question asks for a condition that prevents autogamy but allows geitonogamy. This means that while the pollen cannot fertilize the ovules of the same flower, it can still fertilize the ovules of another flower on the same plant.

3. **Evaluate the Options**:
- **Self-Incompatibility**: This is a genetic mechanism where the pollen from the same flower cannot fertilize its ovules. However, it can still fertilize the ovules of another flower on the same plant. Therefore, this condition prevents autogamy but not geitonogamy.
- **Non-synchronization of Pollen and Anther Release**: This condition can prevent both autogamy and geitonogamy depending on the timing of pollen release and stigma receptivity.
- **Municious Condition**: In this condition, both autogamy and geitonogamy can occur since the flowers are bisexual.
- **Unisexual Condition**: In this case, neither autogamy nor geitonogamy can occur since the flowers are either male or female.

4. **Conclusion**:
- The correct answer is **Self-Incompatibility**, as it prevents autogamy (same flower) but allows geitonogamy (different flowers of the same plant).

### Final Answer:
The condition in which autogamy is prevented but not geitonogamy is **Self-Incompatibility**.