The deficiency of which element is responsible for heart rot of beetroot?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which element's deficiency leads to heart rot in beetroot.

2. **Identifying the Disease**: Heart rot is a specific disease that affects beetroot, characterized by the browning and decay of the inner part of the root.

3. **Recognizing the Nutrient**: Research indicates that the deficiency of boron (B) is responsible for heart rot in beetroot. Boron is classified as a micronutrient essential for plant health.

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