Question

Younger leaves show signs of deficiency symptoms first from the

• A. Calcium
• B. Magnesium
• C. Nitrogen
• D. Sulphur

Hint:

Remember the mobility rules:
Mobile (N, P, K, Mg) $\rightarrow$ Symptoms on Older Leaves first.
Immobile (S, Fe, Mn) $\rightarrow$ Symptoms on Younger Leaves first.
Highly Immobile (Ca, B) $\rightarrow$ Symptoms on Terminal Buds/Growing Tips first.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Nutrient deficiency symptoms on plants appear on specific leaves depending on the mobility of that nutrient within the phloem tissue.

Step 2: Detailed Explanation:
Highly mobile nutrients (like Nitrogen, Phosphorus, Potassium, and Magnesium) are easily translocated from older, lower leaves to actively growing new tissues.
Consequently, older leaves show deficiency symptoms first.
Conversely, immobile or moderately immobile nutrients (like Calcium, Sulphur, Iron, and Boron) cannot be easily translocated from older tissues.
Therefore, young growing leaves suffer first, and deficiency symptoms are displayed on younger leaves first.
Sulphur is a classic moderately immobile nutrient where deficiency causes uniform chlorosis (yellowing) that starts on the younger leaves first (similar to nitrogen deficiency, but nitrogen begins on older leaves).
Although Calcium deficiency is also seen on younger leaves, it primarily targets the terminal buds, causing tip necrosis and distortions.
Standard agricultural exams identify Sulphur as the classic nutrient showing younger leaf chlorosis.

Step 3: Final Answer:
Younger leaves show signs of deficiency symptoms first from Sulphur.