Question

Which of the following crop has less water requirement for its cultivation?

• A. Maize
• B. Bajra
• C. Rice
• D. Sugarcane

Hint:

Typical Crop Water Requirements:
- Sugarcane: $1500\text{--}2500\text{ mm}$
- Rice: $1200\text{--}1500\text{ mm}$
- Maize: $500\text{--}800\text{ mm}$
- Bajra (Pearl Millet): $250\text{--}350\text{ mm}$ (Lowest)
Millets consume significantly less water than major cereals and commercial cash crops.

Answer 1

The Correct Option is B

Concept:
Water requirement (WR) is the total quantity of water, regardless of source, needed by a crop for its transpiration, metabolic activities, and unavoidable evaporative and application losses during its full growth period.
Different field crops show wide variation in total water requirement due to differences in photosynthetic pathways ($\text{C}_3$ vs. $\text{C}_4$), root architecture, transpiration efficiency, and total duration in the field.

Step 1: Evaluating Total Water Requirements of the Options:
- Rice (Oryza sativa): $1200\text{--}1500\text{ mm}$ (very high water requirement due to continuous ponding and high percolation losses).
- Sugarcane (Saccharum officinarum): $1500\text{--}2500\text{ mm}$ (highest total water requirement among field crops due to its long life cycle of $12\text{--}18$ months).
- Maize (Zea mays): $500\text{--}800\text{ mm}$ (moderate water requirement).
- Bajra Pearl Millet (Pennisetum glaucum): $250\text{--}350\text{ mm}$ (lowest water requirement).

Step 2: Physiological Basis of Low Water Requirement in Bajra:
Bajra is an exceptionally drought-hardy $\text{C}_4$ cereal adapted to arid and semi-arid ecosystems.
It possesses a deep, extensive root system, high water-use efficiency (WUE), and effective physiological mechanisms to minimize transpiration under moisture stress.

Step 3: Comparison and Synthesis:
Comparing the four crops, Bajra requires the least amount of total water ($250\text{--}350\text{ mm}$) to complete its lifecycle and yield economic returns.

Step 4: Final Answer:
Therefore, Bajra has the lowest water requirement among the given crops, which is option (B).