Deficiency symptom of relatively immobile elements (e.g. Ca) first appear in

Answer

**Step-by-Step Solution:**

1. **Understanding Mobile vs. Immobile Elements:**
- In plants, nutrients can be classified into two categories: mobile and immobile elements. Mobile elements can move from older tissues to younger tissues, while immobile elements remain in the tissues where they were originally formed.

2. **Identifying Immobile Elements:**
- Calcium (Ca) is an example of an immobile element. Other immobile elements include sulfur (S) and boron (B). These elements are essential for various physiological functions in plants.

3. **Deficiency Symptoms in Immobile Elements:**
- When there is a deficiency of immobile elements like calcium, the symptoms will not be observed in older leaves because these elements do not move from the older parts of the plant. Instead, the deficiency symptoms will first appear in the younger leaves.

4. **Conclusion:**
- Therefore, the deficiency symptoms of relatively immobile elements, such as calcium, first appear in the younger leaves of the plant.

**Final Answer:**
The deficiency symptoms of relatively immobile elements (e.g., Ca) first appear in the younger leaves.

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