Which nutrient deficiency is typically indicated by pale green leaves with older leaves yellowing?

• A. Nitrogen deficiency
• B. Iron deficiency
• C. Potassium deficiency
• D. Magnesium deficiency

Answer: (A)

The situation described shows a mobile nutrient deficiency pattern: the plant reabsorbs the nutrient from older leaves to support new growth, so the oldest foliage bears the symptoms first. Nitrogen is a macronutrient essential for chlorophyll and overall growth, and when it’s deficient, leaves become pale green because chlorophyll production drops, with the oldest leaves yellowing as nitrogen is relocated to newer tissue. This fits nitrogen deficiency best.

Iron deficiency, by contrast, tends to affect new growth first, causing interveinal yellowing in young leaves. Potassium deficiency often shows yellowing or browning at leaf margins on older leaves. Magnesium deficiency usually presents yellowing between veins in older leaves while veins stay green.