Deficiency symptoms of readily mobilised essential elements will first appear in_____

Options

A. (a) younger tissues
B. (b) older tissues
C. (c) roots
D. (d) shoots

Explanation

To solve the question, "Deficiency symptoms of readily mobilised essential elements will first appear in_____," we can follow these steps:

### Step-by-Step Solution:

1. **Identify Readily Mobilised Essential Elements**:
- Understand that readily mobilised essential elements include nitrogen, phosphorus, magnesium, and potassium. These elements can be easily moved within the plant.

2. **Understand Tissue Development**:
- Recognize that plants have different types of tissues, primarily young (developing) tissues and older (mature) tissues. Young tissues are actively growing and require more nutrients.

3. **Nutrient Transport in Plants**:
- Realize that when there is a deficiency, the plant will prioritize the transport of these essential elements to the young and developing tissues. This is because these tissues are crucial for growth and development.

4. **Deficiency Symptoms Appearance**:
- Since the older tissues are not receiving these essential elements (as they are being transported to the younger tissues), they will start to show deficiency symptoms first. This is because the older tissues are lacking these nutrients due to their mobilization to the younger parts of the plant.

5. **Conclusion**:
- Therefore, the deficiency symptoms of readily mobilised essential elements will first appear in the older tissues of the plant.

### Final Answer:
The correct answer is **option B: older tissues**.

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