Yield of Rice is enhanced by

Options

A. Azotobacter
B. Anabaena
C. Cylindrospermum
D. Clostridium

Answer

To answer the question about how the yield of rice is enhanced, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Importance of Nitrogen for Rice Growth**:
- Rice plants require nitrogen for their growth and development. Nitrogen is a crucial component of amino acids, proteins, and nucleic acids.

2. **Identify Nitrogen-Fixing Bacteria**:
- Nitrogen-fixing bacteria are essential for converting atmospheric nitrogen (N₂) into ammonia (NH₃), which can be utilized by plants.

3. **Consider the Options Given**:
- The options provided are Azotobacter, Anabaena, Cylindrospermum, and Clostridium. We need to determine which of these is associated with enhancing rice yield.

4. **Analyze Each Option**:
- **Azotobacter**: This is a nitrogen-fixing bacterium but does not form a symbiotic relationship with rice plants.
- **Anabaena**: This bacterium is known for its symbiotic relationship with the water fern Azolla. Together, they help in fixing atmospheric nitrogen, which is beneficial for rice cultivation.
- **Cylindrospermum**: This is a filamentous cyanobacterium but is not specifically associated with increasing rice yield.
- **Clostridium**: This is a group of bacteria that can be pathogenic and is not related to enhancing rice yield.

5. **Conclude the Correct Answer**:
- Based on the analysis, the correct answer is **Anabaena**, as it works in association with Azolla to enhance nitrogen availability, thereby increasing the yield of rice.

### Final Answer:
The yield of rice is enhanced by **Anabaena** through its symbiotic relationship with the water fern Azolla.

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