Question

Necrosis of apical meristem is the deficiency of _______

• A. Copper
• B. Boron
• C. Calcium
• D. Potassium

Hint:

Calcium is highly immobile and is a key component of the middle lamella (as calcium pectate).
Deficiency leads to cell wall collapse, causing hook-tipped young leaves and necrosis of shoot and root tips.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Nutrient deficiency symptoms are tied to the biochemical roles and vascular mobility of plant nutrients.
Deficiencies of highly immobile structural components appear first at growing points like shoot and root tips (apical meristems).

Step 2: Detailed Explanation:
Calcium ($\text{Ca}$) is an essential plant macronutrient that plays a structural role in stabilizing cell walls and membranes.
It is a key component of calcium pectate, which acts as the cementing agent in the middle lamella that binds adjacent plant cells together.
Calcium is also a messenger in metabolic regulation and is required for mitotic spindle formation during cell division.
In the vascular system, calcium is highly immobile and moves slowly through the xylem via transpiration. It cannot be re-mobilized from older tissues to meet the needs of new growth.
Because apical meristems undergo rapid cell division and growth, they require a continuous supply of calcium.
Under calcium deficiency, new cell walls cannot form properly, leading to cell wall collapse, tissue disintegration, and rapid necrosis (death) of the apical meristem.
This deficiency is also characterized by young leaves that are distorted with hooked tips (e.g., "tipburn" in lettuce or "blossom-end rot" in tomatoes).
While boron deficiency also affects growing points, its primary symptoms include corky tissue, hollow stems, and brittle leaves.

Step 3: Final Answer:
Necrosis of the apical meristem is caused by a deficiency of Calcium, which corresponds to Option (C).