Deficiency of mineral elements showing the symptoms at first in older leaves are:

Options

A. CI and Mg
B. N and S
C. Mg and Ca
D. S and Ca

Answer

To answer the question regarding which mineral elements show deficiency symptoms first in older leaves, we can follow these steps:

### Step 1: Understanding Mobilization of Mineral Elements
- **Explanation**: Some mineral elements are highly mobilized within the plant. This means that when there is a deficiency, these elements can be transported from older tissues (like older leaves) to younger tissues (like new leaves and growing parts).
- **Hint**: Think about how plants prioritize their resources; they often move nutrients to where they are most needed.

### Step 2: Identifying Mobilized Elements
- **Explanation**: The main mineral elements that are highly mobilized include nitrogen, potassium, and magnesium. When these elements are deficient, the first symptoms will appear in the older leaves because the plant reallocates these nutrients to support new growth.
- **Hint**: Remember that elements that are crucial for growth and development are often prioritized by the plant.

### Step 3: Identifying Immobile Elements
- **Explanation**: In contrast, some elements like calcium and sulfur are not mobilized. These elements remain in the older tissues and do not move to younger tissues. Therefore, deficiencies in these elements will not show symptoms in older leaves.
- **Hint**: Consider the role of structural elements in plants; they often stay put and support the structure rather than being moved around.

### Step 4: Conclusion on Symptoms in Older Leaves
- **Explanation**: Since nitrogen, potassium, and magnesium are mobilized, their deficiencies will manifest first in older leaves. Therefore, the correct answer to the question is that deficiencies of nitrogen, potassium, and magnesium will show symptoms first in older leaves.
- **Hint**: Focus on which elements are essential for growth and can be moved around within the plant.

### Final Answer
The mineral elements whose deficiency shows symptoms first in older leaves are nitrogen, potassium, and magnesium.