Agronomy Degree Practice Exam

What is the first visual symptom of a nitrogen deficiency in a plant?

1. Chlorosis

2. Dampening-off

3. Wilting

4. Rickets

The correct answer is: Chlorosis

Chlorosis is the primary visual symptom of nitrogen deficiency in plants, characterized by a yellowing of the leaves due to insufficient chlorophyll production. Nitrogen is an essential nutrient for plants, integral to the formation of amino acids and proteins, and its deficiency leads to reduced chlorophyll synthesis. As a result, the leaves start to turn yellow, particularly in older leaves, because nitrogen is mobile within the plant, and it is often reallocated to younger tissues when the plant is under stress. In contrast, dampening-off refers to a group of fungal diseases affecting seedlings, generally arising from overly moist conditions, and does not relate to nutrient deficiency. Wilting typically results from water stress or lack of hydration, not from a nitrogen deficiency. Rickets is a condition that affects bone development in humans and is not applicable to plants. Understanding chlorosis as the first sign of nitrogen deficiency helps agronomists and growers diagnose and address nutrient deficiencies promptly to maintain healthy plant growth and development.