A nutrient deficiency of plants that first appears on young leaves as an interveinal chlorosis is:

• A. Nitrogen
• B. Iron
• C. Magnesium
• D. Phosphorus

Answer: (B)

That pattern—interveinal chlorosis appearing first on the newest leaves—is characteristic of iron deficiency. Iron is essential for chlorophyll synthesis, but it is not moved efficiently within the plant, so when iron is short, the young, actively growing leaves can’t form chlorophyll properly. The result is yellowing between the veins while the veins themselves stay green, a classic sign of iron deficiency. Since the deficiency affects the new growth first, the symptoms show up on young leaves before older ones. This contrasts with nitrogen deficiency, where older leaves yellow because nitrogen is mobile and can be relocated to support new growth, or magnesium deficiency, which also causes interveinal chlorosis but on older leaves because magnesium is more mobile within the plant. Phosphorus deficiency tends to produce stunted growth and other color changes rather than the distinct interveinal pattern on new leaves.