In legumes, root nodules formation is inhibited by deficiency of :

Options

A. Mo
B. B
C. Cu
D. Mn

Answer

To solve the question regarding the inhibition of root nodule formation in legumes due to mineral deficiency, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Root Nodules in Legumes**:
- Legumes, such as peas and beans, form specialized structures called root nodules. These nodules are essential for nitrogen fixation, a process where atmospheric nitrogen is converted into a form usable by plants.

2. **Identifying the Key Minerals**:
- The question provides four options: Molybdenum (Mo), Boron (B), Copper (Cu), and Manganese (Mn). Each of these minerals plays a role in plant nutrition and development.

3. **Researching the Role of Each Mineral**:
- **Molybdenum (Mo)**: Important for nitrogen fixation as it is a part of the enzyme nitrogenase.
- **Boron (B)**: Essential for cell wall formation and is crucial for the development of root nodules in legumes.
- **Copper (Cu)**: Plays a role in photosynthesis and respiration but is not directly linked to nodule formation.
- **Manganese (Mn)**: Involved in photosynthesis and enzyme activation but does not directly inhibit nodule formation.

4. **Determining the Correct Answer**:
- Based on the research, Boron is specifically noted for its role in the formation of root nodules in legumes. A deficiency in Boron can inhibit the development of these nodules, leading to reduced nitrogen fixation.

5. **Conclusion**:
- Therefore, the correct answer to the question is **Boron (B)**, as its deficiency inhibits root nodule formation in legumes.

### Final Answer:
**Boron (B)**

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