Nitrogen is a mobile nutrient. The plant can move it around where it's needed. Because of that, Nitrogen deficiency starts at the oldest growth (bottom of the plant) first. Iron and Zinc are immobile deficiencies, so the plant can't move them around. These deficiencies start at the new growth (top of plant).
We can be 100% certain that this isn't being caused by a Nitrogen deficiency. In fact, as I said earlier, there's actually N toxicity showing in the plants.
Also, you don't need to mention me in your posts.
