Which elements are called micronutri ents? Name any four.

Explanation

### Step-by-Step Solution:

1. **Definition of Micronutrients**: Micronutrients, also known as micro-elements or trace elements, are essential nutrients required by plants in very small quantities. They play crucial roles in various physiological processes.

2. **Characteristics of Micronutrients**: These nutrients are typically required in amounts less than 10 millimoles per kilogram of dry matter in plants. Despite being needed in small amounts, they are vital for plant growth and development.

3. **Examples of Micronutrients**: There are several elements classified as micronutrients. Here are four examples:
- **Boron (B)**: Important for cell wall formation and reproductive development.
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