In order to increase the yield of the cereal crops the farmer rotated the crop with pulses. The increase in yield occurred due to the action of

Options

A. Clostridium butylicum
B. Bacillus denitrificans
C. Rhizobium leguminosarum
D. Nitrosomonas

Answer

To answer the question regarding the increase in yield of cereal crops due to crop rotation with pulses, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Crop Rotation**: Crop rotation is an agricultural practice where different crops are grown in succession on the same land. This practice helps in maintaining soil fertility and reducing pest and disease cycles.

2. **Identifying the Role of Pulses**: Pulses, such as beans and lentils, are known to have a symbiotic relationship with certain bacteria that can fix atmospheric nitrogen. This is crucial because nitrogen is an essential nutrient for plant growth.

3. **Recognizing Nitrogen-Fixing Bacteria**: The bacteria that are primarily responsible for nitrogen fixation in the roots of pulse plants are from the genus **Rhizobium**. These bacteria convert atmospheric nitrogen (N₂) into ammonia (NH₃), which plants can use.

4. **Explaining the Symbiotic Relationship**: In this symbiotic relationship, Rhizobium bacteria inhabit the root nodules of pulse plants. They provide the plants with nitrogen, which enhances their growth and, in turn, the plants supply the bacteria with carbohydrates and a suitable environment.

5. **Impact on Soil Fertility**: The presence of Rhizobium increases the nitrogen content in the soil, which benefits subsequent crops, such as cereals, leading to an increase in their yield.

6. **Conclusion**: Therefore, the increase in yield of cereal crops due to crop rotation with pulses is primarily due to the action of **Rhizobium**, which enhances soil nitrogen levels through nitrogen fixation.

### Final Answer:
The increase in yield occurred due to the action of **Rhizobium**.

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