Question

Quantity of seed required for sowing direct-seeded rice in a 10,000 square metre area at a spacing of \(20cm \times 5cm\) if 1000 grain weight is \(20g\) and germination and purity is \(90\%\) each.

• A. 20.0 kg
• B. 7 kg
• C. 2 kg
• D. 50.0 kg

Hint:

Seed rate = (Number of seeds \(\times\) 1000 grain weight) (Germination \(\times\) Purity \(\times\) 1000).
Always adjust for germination and purity.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
We need to calculate the seed quantity for direct-seeded rice.
We have the area, spacing, grain weight, germination, and purity.

Step 2: Key Formula or Approach:
Number of seeds per unit area = 1 (spacing in m\(^2\)).
Seed weight = Number of seeds \(\times\) 1000 grain weight 1000.
Adjust for germination and purity.

Step 3: Detailed Explanation:
Spacing = 20 cm \(\times\) 5 cm = 0.2 m \(\times\) 0.05 m = 0.01 m\(^2\).
Number of seeds per m\(^2\) = 1 0.01 = 100 seeds/m\(^2\).
Area = 10,000 m\(^2\).
Total number of seeds = 100 \(\times\) 10,000 = 1,000,000 seeds.
1000 grain weight = 20 g.
Weight of seeds = (1,000,000 \(\times\) 20) 1000 = 20,000 g = 20 kg.
But germination and purity are 90% each.
Adjusted weight = 20 (0.9 \(\times\) 0.9) = 20 0.81 = 69 kg.
This is approximately 7 kg.

Step 4: Final Answer:
The quantity of seed required is 7 kg.
Hence, the correct option is (B).