Question

Given below are two statements, one is labeled as Assertion (A) and the other one is labeled as Reason (R).
Assertion (A) : Water requirement for wheat crops varies from 300 to 600 mm.
Reason (R) : Water requirement varies depending on the soil type and rainfall and variety.

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

Hint:

The total water requirement of a crop is a dynamic value. It is always governed by the local climatic demand (rainfall, temperature), soil physical properties, and crop genetics (variety).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Crop water requirement (WR) is the total depth of water needed to meet evapo-transpirational demands and metabolic needs of a crop during its growth cycle under field conditions.

Step 3: Detailed Explanation:
Let us analyze the Assertion and the Reason individually:
- Assertion (A) is correct: The total water requirement of a wheat crop under Indian conditions typically varies between 300 to 600 mm (or 350 to 550 mm). This depth is usually met through a combination of irrigation water and natural rainfall during the rabi season.
- Reason (R) is correct: The water requirement is not a static constant. It varies widely based on:
1. Soil Type: Heavy clay soils hold more water but can have high evaporation, while sandy soils have low water holding capacity, necessitating more frequent irrigations and changing water requirements.
2. Rainfall: Atmospheric humidity and rainfall directly alter the irrigation water requirement.
3. Variety: Short-duration varieties need less total water than long-duration cultivars, and some varieties have higher water-use efficiency.
- Analysis of Explanation: The variation in the water requirement of wheat (from 300 to 600 mm, as stated in the Assertion) is caused directly by differences in soil types, seasonal rainfall patterns, and the specific cultivar grown (as explained in the Reason). Thus, the Reason is the correct explanation of the Assertion.
Therefore, Both (A) and (R) are correct, and (R) is the correct explanation of (A).

Step 4: Final Answer:
Both (A) and (R) are correct, and (R) is the correct explanation of (A).