Which symptom is not associated with nitrogen deficiency in plants?

The symptom that is not associated with nitrogen deficiency in plants is dark bluish green plants. Nitrogen is a vital nutrient for plants and is essential for synthesizing chlorophyll, which is important for photosynthesis. When plants are deficient in nitrogen, they often exhibit symptoms such as pale green leaves, poor growth, and yellowing leaves, as nitrogen is crucial for leaf development and overall vigor.

On the other hand, dark bluish green foliage typically indicates an excess of nitrogen rather than a deficiency. Plants that have access to sufficient or excessive nitrogen can develop a deep, rich green color due to increased chlorophyll production. Therefore, the presence of dark bluish green plants is not a symptom that would be expected in cases of nitrogen deficiency.