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Agronomy QUESTION #2064
Question 1
Zinc deficiency, the most widespread micronutrient deficiency in Pakistan and South Asia, is characterized by:
  • Dark green, crinkled older leaves with necrotic margins
  • Interveinal chlorosis and stunting of older leaves due to Zn mobility
  • Stunted young leaves, shortened internodes (little leaf/khaira disease in rice), interveinal chlorosis on young leaves, and delayed maturity — due to Zn's role in auxin synthesis and enzyme activation✔️
  • Pale yellow coloration of the entire plant with early senescence
Correct Answer Explanation
Zn deficiency causes little leaf/rosette in fruit trees, khaira disease in rice, and white bud in maize. Young leaves are affected first (Zn is relatively immobile in phloem). Zn activates >300 enzymes, is required for IAA synthesis, RNA polymerase, and ribosome structure. ZnSO₄ (21% Zn) applied at 25 kg/ha corrects deficiency.