Which is used as biofertilizer

Options

A. Azolla
B. Marchantia
C. Funaria
D. Dryopteris

Answer

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four options: Azolla, Margantia, Humaria, and Triopetris.

2. **Understand Biofertilizers**: Biofertilizers are substances that contain living microorganisms which promote plant growth by increasing the availability of nutrients to the host plant.

3. **Analyze Each Option**:
- **Azolla**: A water fern that has a symbiotic relationship with cyanobacteria (specifically Anabaena), which can fix atmospheric nitrogen.
- **Margantia**: A liverwort, not commonly known for its role as a biofertilizer.
- **Humaria**: A type of fungus, not typically used as a biofertilizer.
- **Triopetris**: Not widely recognized as a biofertilizer.

4. **Focus on Azolla**:
- Azolla contains Anabaena, which is a blue-green algae (cyanobacteria) capable of nitrogen fixation.
- The nitrogenase enzyme present in Anabaena allows it to convert atmospheric nitrogen into a form that plants can use.

5. **Impact on Agriculture**:
- The fixed nitrogen from Azolla is utilized by rice plants in paddy fields, enhancing their growth and yield.
- This characteristic makes Azolla a valuable biofertilizer in rice cultivation.

6. **Conclusion**: Based on the analysis, Azolla is the correct answer as it is used as a biofertilizer due to its nitrogen-fixing capabilities.

### Final Answer: Azolla

---