Farmers have reported over `50%` higher yields of rice by using which of the following biofertilisers ?

Options

A. Bacillus thuringiensis
B. Lagume-Rhizobium symbiosis
C. Mycorrhizae
D. Azolla pinnata

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question asks which biofertilizer has been reported to increase rice yields by over 50%.

2. **Identifying the Options:**
The options provided are:
- A) Bacillus thuringiensis
- B) Legume rhizobium symbiosis
- C) Mycorrhiza
- D) Azolla pinnata

3. **Analyzing Each Option:**
- **Bacillus thuringiensis:** This is a bacterium used primarily as a pesticide, not a biofertilizer for rice.
- **Legume rhizobium symbiosis:** This is beneficial for legumes, not specifically for rice.
- **Mycorrhiza:** These fungi form symbiotic relationships with many plants but are not specifically known for enhancing rice yields significantly.
- **Azolla pinnata:** This is a free-floating freshwater fern that grows rapidly and is known to form a symbiotic relationship with the cyanobacteria Anabaena. This association helps in nitrogen fixation, which is crucial for rice cultivation.

4. **Conclusion:**
Based on the analysis, Azolla pinnata is the biofertilizer that has been reported to increase rice yields by over 50%.

5. **Final Answer:**
The correct answer is **D) Azolla pinnata**.

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