Question

The region of the soil around the root surface is called

• A. Rhizosphere
• B. Endosphere
• C. Phyllosphere
• D. Hydrosphere

Hint:

To remember the plant-microbe zones: "Rhizo-" refers to roots (Rhizosphere = soil around roots), "Phyllo-" refers to leaves (Phyllosphere = leaf surfaces), and "Endo-" refers to internal tissues (Endosphere = inside the plant).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Plant roots do not exist in an inert soil environment.
They interact continuously with the surrounding soil by releasing organic carbon compounds, absorbing water, and exchanging inorganic ions.
This creates a distinct biological micro-environment immediately adjacent to the root surface.

Step 2: Detailed Explanation:
Let us define the environmental zones associated with plants:
Rhizosphere (A): This is the narrow zone of soil directly surrounding and influenced by plant roots.
It is characterized by intense microbial activity driven by root exudates (such as sugars, amino acids, and organic acids) released by the roots.
These exudates serve as energy sources for diverse soil bacteria and fungi, creating a unique biome critical for plant nutrition, pathogen defense, and soil structure.
Endosphere (B): This refers to the internal tissues of the plant (such as the root cortex or vascular bundle) that are colonized by symbiotic or endophytic microorganisms.
Phyllosphere (C): This is the above-ground surface of plants, primarily the leaves, colonized by specialized microorganisms.
Hydrosphere (D): This is the collective water mass of the Earth, unrelated to the direct root-soil interface.
Therefore, the soil region directly surrounding the root surface is the rhizosphere.

Step 3: Final Answer:
The region of soil around the root surface is called the Rhizosphere, which corresponds to option (A).