Leguminous plants are important in agriculture because

Options

A. They are disease resistant
B. They have high amounts of proteins
C. They require less nitrogen for growth
D. Nitrogen fixing bacteria are symbiotically associated in them.

Answer

**Step-by-Step Solution:**

1. **Understanding Leguminous Plants**: Leguminous plants, such as beans, peas, and lentils, belong to the family Fabaceae. They are unique in their ability to form symbiotic relationships with nitrogen-fixing bacteria.

2. **Role of Nitrogen in Agriculture**: Nitrogen is an essential nutrient for plant growth, as it is a major component of amino acids, proteins, and nucleic acids. However, plants cannot directly absorb atmospheric nitrogen (N2), which makes up about 78% of the atmosphere.

3. **Nitrogen Fixation**: Certain bacteria, such as Rhizobium, can convert atmospheric nitrogen into a form that plants can use (like ammonia). This process is known as nitrogen fixation.

4. **Symbiotic Relationship**: Leguminous plants provide a habitat for these nitrogen-fixing bacteria in their root nodules. In return, the bacteria convert nitrogen from the atmosphere into a usable form for the plants. This mutual relationship benefits both organisms.

5. **Evaluating the Options**:
- **Option A**: "They are disease resistant" - This is not a primary reason for their importance in agriculture.
- **Option B**: "They have high amounts of protein" - While legumes are a good source of protein, this is not the main agricultural significance.
- **Option C**: "They require less nitrogen for growth" - This is misleading; they actually require nitrogen but can obtain it through their symbiotic relationship.
- **Option D**: "Nitrogen-fixing bacteria are symbiotically associated with them" - This is the correct option, as it highlights the crucial role of these bacteria in enhancing soil fertility and supporting plant growth.

6. **Conclusion**: The importance of leguminous plants in agriculture primarily lies in their ability to form a symbiotic relationship with nitrogen-fixing bacteria, which enriches the soil with nitrogen, making it more fertile for subsequent crops.

**Final Answer**: Leguminous plants are important in agriculture because nitrogen-fixing bacteria are symbiotically associated with them.

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