Texas FFA Nursery Landscape Practice Exam

Plants showing symptoms of nitrogen deficiency will most likely exhibit which symptom?

1. A. Tiny brown spots between the leaf veins

2. B. Yellowing of the entire leaf

3. C. Abnormally long internodes

4. D. Purple veins in the leaves

The correct answer is: B. Yellowing of the entire leaf

When plants experience nitrogen deficiency, one of the most notable symptoms is the yellowing of the leaves, which is specifically referred to as chlorosis. This phenomenon occurs because nitrogen is a crucial component of chlorophyll, the pigment responsible for the green color in plants and essential for photosynthesis. Without adequate nitrogen, plants cannot produce sufficient chlorophyll, leading to a yellowing effect that often starts with the older leaves first, as they typically hold the majority of the plant's nitrogen reserves. The other symptoms provided, such as tiny brown spots, abnormally long internodes, and purple veins, are typically associated with different nutrient deficiencies or plant stress conditions. For example, tiny brown spots may indicate a potassium deficiency, while purple veins can often relate to phosphorus deficiency. Chlorosis due to nitrogen deficiency is extensive across the leaf, affecting its function and health significantly, making yellowing the most characteristic symptom of this particular deficiency.