Biofertilisers include

Options

A. Nitrogen fixing bacteria
B. Mycorrhiza
C. Nitrogen fixing cyanobacteria
D. All the above

Answer

**Step-by-Step Solution:**

1. **Understanding Biofertilizers**: Biofertilizers are substances that contain living microorganisms which promote plant growth by increasing the supply or availability of primary nutrients to the host plant. They are often derived from natural sources.

2. **Types of Biofertilizers**: Biofertilizers can be categorized into three main types:
- **Nitrogen-Fixing Bacteria**: These are bacteria that can convert atmospheric nitrogen into a form that plants can absorb and utilize.
- **Cyanobacteria**: Also known as blue-green algae, these microorganisms can also fix atmospheric nitrogen and are often found in aquatic environments.
- **Mycorrhizae**: These are fungi that form symbiotic relationships with plant roots, enhancing nutrient and water uptake for the plant.

3. **Conclusion**: Based on the types of biofertilizers mentioned, it can be concluded that biofertilizers include nitrogen-fixing bacteria, cyanobacteria, and mycorrhizae.

4. **Final Answer**: Therefore, the correct answer to the question "Biofertilisers include" is "all of the above" (option number four).

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