Question

Vesicular Arbuscular Mycorrhizae play active role in increasing the availability of -

• A. N
• B. P
• C. Ca
• D. S

Hint:

VAM = Phosphorus (P).
Hyphae are like "Extensions" for roots.
They turn a "Short" root into a "Long" foraging network for phosphate.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify the specific nutrient whose uptake is most significantly enhanced by the symbiotic relationship between plant roots and VAM fungi.
Detailed Explanation:

• What is VAM?
Vesicular Arbuscular Mycorrhizae (VAM) are endomycorrhizal fungi that penetrate the cortical cells of plant roots. They form specialized structures: "Vesicles" for storage and "Arbuscules" for nutrient exchange.

• Phosphorus (P) Dynamics:
Phosphorus is a highly immobile nutrient in the soil. It moves primarily by diffusion, creating a "depletion zone" immediately around the root where P is exhausted.

• Mechanism of Action:
The fungal hyphae extend far beyond the root's reach into the surrounding soil.
By significantly increasing the surface area for absorption and reaching into pores too small for root hairs, the fungi capture phosphate ions and transport them back to the plant.
This is especially critical in P-deficient or acidic/alkaline soils where P is fixed and unavailable.

• Other Nutrients:
While VAM can assist in the uptake of micronutrients like Zn and Cu, its role in Phosphorus mobilization is its most defining and vital agricultural benefit.

Step 2: Final Answer:
VAM fungi are predominantly associated with increasing the availability and absorption of Phosphorus.