Which is a key deficiency symptom for nitrogen in crops?

Which is a key deficiency symptom for nitrogen in crops?

• A. Older leaf yellowing
• B. Stunted growth with dark green leaves
• C. Marginal scorch on older leaves
• D. Uniform light yellowing

Answer: (A)

Nitrogen is a mobile nutrient in plants, so when it's in short supply the plant pulls nitrogen from older leaves to support new growth. This causes chlorosis (yellowing) of the older leaves while the newer leaves stay greener. That pattern—older leaves turning yellow first—is the telltale sign of nitrogen deficiency. Other signs like marginal scorch on older leaves point to potassium deficiency, and uniform light yellowing can result from different issues and doesn’t match the nitrogen mobility pattern.

Nitrogen is a mobile nutrient in plants, so when it's in short supply the plant pulls nitrogen from older leaves to support new growth. This causes chlorosis (yellowing) of the older leaves while the newer leaves stay greener. That pattern—older leaves turning yellow first—is the telltale sign of nitrogen deficiency. Other signs like marginal scorch on older leaves point to potassium deficiency, and uniform light yellowing can result from different issues and doesn’t match the nitrogen mobility pattern.