Question

Vesicular Arbuscular Mycorrhiza has an important role in increasing the availability of

• A. Potassium
• B. Phosphorus
• C. Sulphur
• D. Zinc

Hint:

Phosphorus is highly immobile in soil.
VAM hyphae extend beyond the root depletion zone, increasing the effective surface area for phosphorus uptake.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Vesicular Arbuscular Mycorrhiza (VAM) is a symbiotic association formed between certain soil fungi and plant roots.
This association enhances the plant's ability to absorb nutrients with low mobility in the soil solution.

Step 2: Detailed Explanation:
Phosphorus ($P$) is highly immobile in soil due to precipitation and adsorption reactions, forming insoluble compounds with iron and aluminum in acidic soils, and with calcium in alkaline soils.
Consequently, a depletion zone of available orthophosphate forms immediately around plant roots.
The fungal hyphae of VAM extend past this depletion zone, creating an extensive network that increases the effective surface area of the root system.
VAM fungi also secrete organic acids and phosphatases that solubilize bound inorganic phosphorus and mineralize organic phosphorus.
This symbiotic system improves the uptake of phosphorus, particularly in low-fertility soils.
While VAM can also support the uptake of other micronutrients like zinc, its primary and most significant role is in increasing the availability and absorption of phosphorus.

Step 3: Final Answer:
Vesicular Arbuscular Mycorrhiza plays an important role in increasing the availability of Phosphorus, which corresponds to Option (B).