Answer: Little leaf disease (shortened internodes, small malformed leaves).
- A Interveinal chlorosis appearing first in the youngest leaves
- B Little leaf disease (shortened internodes, small malformed leaves)
- C Purple coloration spreading across mature leaf surfaces
- D Scorching and browning along the tips of older leaves
Correct answer: B. Little leaf disease (shortened internodes, small malformed leaves)
Explanation: Zinc deficiency causes 'little leaf' or 'rosette' disease - very short internodes and small, narrow, chlorotic leaves that cluster. Zinc is needed for synthesis of auxin (IAA) and for several enzymes. Common in maize and rice.
Atmospheric N₂ is fixed into ammonia by nitrogen-fixing bacteria (protected from oxygen by leghaemoglobin in root nodules), converted to nitrate via nitrification for plant uptake, and eventually returned to the atmosphere as N₂ via denitrification, completing the cycle.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.