Question

Deficiency symptoms of nitrogen and potassium are visible first in:

• A. Young leaves
• B. Roots
• C. Buds
• D. Senescent leaves

Answer 1

The Correct Option is D

To understand the deficiency symptoms of nitrogen and potassium in plants, we need to examine which parts of the plant exhibit these symptoms first. Deficiency symptoms are often categorized based on whether they appear in older or younger parts of the plant.

1. Nitrogen Deficiency: Nitrogen is a mobile nutrient in plants; hence, when a plant suffers from a nitrogen deficiency, it will mobilize its internal reserves and translocate nitrogen from older leaves to younger ones. This causes symptoms such as yellowing (chlorosis) to appear first on older, senescent leaves. This is because the plant prioritizes the growth of newer leaves by reallocating nitrogen from older ones.
2. Potassium Deficiency: Similar to nitrogen, potassium is also a mobile nutrient. As a result, symptoms of potassium deficiency, such as marginal leaf burn and chlorosis, first appear on older leaves. The plant maintains potassium levels in growing tissues by moving potassium from older tissues, which leads to deficiency symptoms in the older, senescent leaves.

Given the above explanations, it is clear that the symptoms for both nitrogen and potassium deficiencies first manifest in the senescent leaves due to their mobility within the plant.

Therefore, the correct answer is: Senescent leaves.