Yield of rice is increased by

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks how the yield of rice can be increased. This involves understanding the factors that contribute to rice growth and productivity.

2. **Identifying Key Organisms**: The options provided are different types of bacteria. We need to identify which of these bacteria is known for its role in enhancing rice yield through nitrogen fixation.

3. **Exploring Nitrogen Fixation**: Nitrogen is an essential nutrient for plants, and its availability can significantly affect plant growth. Certain bacteria can convert atmospheric nitrogen into forms that plants can use, such as ammonia or nitrates.

4. **Symbiotic Relationships**: Some aquatic ferns, like Azolla, have a symbiotic relationship with nitrogen-fixing bacteria. This relationship allows the fern to fix atmospheric nitrogen, which can then be utilized by rice plants.

5. **Identifying the Correct Bacteria**: Among the options given, Anabina is known to form a symbiotic relationship with Azolla. This relationship helps in fixing nitrogen, which is crucial for the growth of rice plants.

6. **Conclusion**: Therefore, the yield of rice is increased by the nitrogen-fixing bacteria Anabina, as it helps in providing essential nitrogen to the rice plants through its association with Azolla.

**Final Answer**: The yield of rice is increased by option 2: Anabina.

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