Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Only vegetatively propagated planting are responsible for transboundary movement of pathogens.
Reason (R) : High moisture contents in the vegetative propagation material supports pathogen viability.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Be cautious of absolute terms like "only," "always," or "never" in scientific assertion statements, as they often make the statement false.
While vegetative propagation is a major pathway for pathogen movement, it is not the only pathway.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Transboundary plant diseases are highly contagious epidemic diseases that spread across national borders, threatening global food security.
Analyzing the pathways through which these pathogens are introduced and spread is essential for maintaining strict quarantine measures.

Step 2: Detailed Explanation:
Let us evaluate both the assertion and reason individually:
Assertion (A): "Only vegetatively propagated planting are responsible for transboundary movement of pathogens."
This statement is incorrect.
While vegetatively propagated materials (such as tubers, cuttings, budwood, and bulbs) are major pathways for introducing systemic viruses, bacteria, and fungi across borders, they are not the only pathway.
Pathogens also cross international borders through:
- True seeds (seed-borne pathogens).
- Wind currents carrying lightweight spores (like rust urediniospores) across continents.
- Insect vectors carrying viruses or phytoplasmas.
- Contaminated agricultural soil, packing materials, and farm machinery.
The word "only" makes the assertion false.
Reason (R): "High moisture contents in the vegetative propagation material supports pathogen viability."
This statement is correct.
Vegetatively propagated plant tissues (like potato tubers or sugarcane setts) contain high water content and active metabolic systems.
This moist, living environment protects delicate pathogens (such as bacteria, viruses, and fungi) from drying out, keeping them viable during transport and storage.

Step 3: Final Answer:
Assertion (A) is false, but Reason (R) is true.
This corresponds to Option (D).