Do iron salts increase photosynthesis, or do they increase the size of chloroplasts, or cytochromes when iron is sufficient? In other words, is greening-up functional or structural under these conditions?
There is plenty of research showing how iron deficient plants will "green up" when Fe2+ is applied, usually attributed to increased photosynthesis. Unfortunately, iron is typically over-applied to golf course greens entirely for aesthetic purposes. As a result, Cr, Cu, Mn, Mo, Si, W, and Zn are antagonized, increasing susceptibility to disease, followed by over-application of pesticides.