Plant Science and Crop Production
What this domain tests
Plant Science and Crop Production examines how crop plants grow and how planting decisions change yield. The exam tests photosynthesis and respiration, seed germination, crop seasons, crop rotation, intercropping, plant geometry, and package of practices for crops such as cotton, soybean, paddy, sugarcane, jowar and onion.
Core rules and concepts
- Kharif crops are sown with the monsoon; rabi crops depend on winter temperatures and residual or assured irrigation; zaid is the short summer season.
- Seed quality includes genetic purity, physical purity, germination percentage and vigour; certified seed labels state these values.
- Plant population per hectare = 10,000 ÷ (row spacing in m × plant spacing in m).
- Cropping intensity = (gross cropped area ÷ net sown area) × 100.
- Intercropping differs from mixed cropping: intercrops are sown in definite rows and are harvested separately.
- C3 plants such as paddy and soybean generally have lower photosynthetic efficiency than C4 plants such as maize and sugarcane under high temperature.
Worked example
A cotton field uses 90 cm × 60 cm spacing. Area per plant = 0.90 × 0.60 = 0.54 m². Plants per hectare = 10,000 ÷ 0.54 = 18,518. If 2% of plants are lost, expected stand = 18,518 × 0.98 = 18,148 plants. The reasoning is: convert spacing to metres, find the area occupied by one plant, then divide the hectare area by that figure.
Traps that cost marks
Do not confuse gross cropped area with net sown area. Do not give a seed rate without stating whether it is for a pure crop or an intercrop. Do not treat C3 and C4 examples as interchangeable. If the question asks for plants per acre, convert hectares to acres (1 ha = 2.47 acres) before dividing.