Question

Water use efficiency is

• A. Total water required during crop growth period
• B. Production per unit water applied
• C. Duration of water applied during the crop growth period
• D. Yield of crop per hectare

Hint:

Water Use Efficiency (WUE) is expressed in units of \( \text{kg/ha-mm} \) or \( \text{kg/m}^3 \).
C4 crops (like sorghum and maize) generally have higher water use efficiency than C3 crops (like wheat and rice).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Water Use Efficiency (WUE) is an agronomic index that quantifies how effectively a crop converts the water it consumes (via transpiration or total irrigation) into economic yield (production).
Key Formula or Approach:
Mathematically, WUE is expressed as:
\[ \text{WUE} = \frac{Y}{W} \] where:
- $Y$ is the crop yield or economic production (e.g., $\text{kg/ha}$).
- $W$ is the total volume or depth of water used or applied (e.g., $\text{ha-cm}$ or $\text{mm}$).

Step 2: Detailed Explanation:
Let us evaluate the options:
- Option (A): This describes the "water requirement" of the crop, which is a volume/depth value, not an efficiency ratio.
- Option (B): This describes the ratio of economic crop production to the unit of water applied/consumed, which is the definition of water use efficiency.
- Option (C): This describes the frequency or timing of irrigation.
- Option (D): This is the crop yield per unit area, without relating it to water consumption.

Step 3: Final Answer:
Water use efficiency is defined as production per unit of water applied, corresponding to option (B).