Texas FFA Nursery Landscape Practice Exam

Which color of leaf indicates the presence of phosphorus deficiency?

1. A. Yellow

2. B. Purple

3. C. Brown

4. D. Green

The correct answer is: B. Purple

The presence of phosphorus deficiency in plants is often indicated by the development of a purple coloration in the leaves. This occurs due to the accumulation of sugars and other compounds that cannot be fully utilized without adequate phosphorus. Phosphorus plays a crucial role in energy transfer and photosynthesis, and its lack can disrupt these vital processes, leading to reduced plant vigor and characteristic purple pigments surfacing, especially in older leaves. The other colors mentioned typically point to different nutrient deficiencies or issues. For example, yellowing leaves commonly suggest nitrogen deficiency, while brown leaves may indicate issues such as overwatering or root rot. Green leaves generally signify adequate nutrient availability, particularly nitrogen-rich conditions. This understanding highlights how color changes in foliage serve as visual indicators of plant health and specific nutrient needs.