Which symptom is a typical deficiency sign for potassium in crops?

• A. Stunted growth with dark green leaves
• B. New leaf chlorosis
• C. Marginal scorch on older leaves
• D. Interveinal chlorosis on young leaves

Answer: (C)

Potassium is highly mobile within the plant, so when it’s short, the plant moves what it has to the new growth and away from older tissues. That’s why deficiency symptoms show up first on older leaves. The hallmark is marginal scorch or browning along the leaf edges, sometimes with the tips becoming crisp, on these older leaves. This pattern contrasts with symptoms from immobile micronutrients (like iron), which cause new-leaf chlorosis or interveinal chlorosis on young leaves. Stunted growth with dark green leaves isn’t the typical sign of potassium deficiency. So the marginal scorch on older leaves best reflects a potassium deficiency.