Farmers have reported 50% higher yield of rice by using biofertilizer

Options

A. Rhizobium culture
B. Cyanobacteria
C. Mycorrhizae
D. Azolla pinnata

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question states that farmers have reported a 50% higher yield of rice by using a specific type of fertilizer. We need to identify which of the given options is a biofertilizer that can enhance rice yield.

2. **Analyzing the Options**:
- **Option 1: Bacillus thuringiensis**: This is a bacterium known for its role in pest control, particularly in cotton plants. It provides disease resistance but does not significantly contribute to rice yield. Therefore, this option is incorrect.

- **Option 2: Legume Rhizobium species**: Rhizobium bacteria are associated with leguminous plants (like peas) and are primarily involved in nitrogen fixation. They do not directly enhance rice yield, making this option incorrect as well.

- **Option 3: Mycorrhiza**: Mycorrhizal fungi form symbiotic relationships with plant roots and help in nutrient absorption. While they are beneficial, they are not specifically known for increasing rice yields by 50%. Thus, this option is also incorrect.

- **Option 4: Azolla pinnata**: Azolla is a free-floating fern that can fix nitrogen in rice paddies. It multiplies rapidly (5 to 7 times) and contributes significantly to soil fertility, which can lead to a substantial increase in rice yield. This makes it the most suitable option for achieving a 50% higher yield.

3. **Conclusion**: Based on the analysis of the options, the correct answer is **Azolla pinnata**, as it is a biofertilizer that effectively enhances rice yield through nitrogen fixation.

### Final Answer:
**Azolla pinnata** is the correct answer for the biofertilizer that leads to a 50% higher yield of rice.

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