Porphyrin Ring in Chlorophyll and Effects of Nitrogen and Magnesium Deficiencies
In chlorophyll, the transfer and construction ring is called the porphyrin ring. If you look at the structure below, you will see that the Mg²⁺ ion is located at the center of this ring, and nitrogen atoms are positioned on four sides, each connected by a bond. When multiple porphyrin rings are placed side by side, they are all connected through nitrogen bonds.
Now, consider what happens during nitrogen deficiency: the bonding connections between the rings are disrupted and break down noticeably. Due to the lack of nitrogen, chlorophyll cannot be synthesized properly and uniformly, and the rings begin to break one after another. As a result, the green color of chlorophyll—which normally absorbs radiation from 400 to 700 nanometers—disappears, and leaves appear uniformly yellow.
The uniform yellow color is due to the failure to produce continuous chlorophyll, which affects the entire leaf. Early in the growth stage, older leaves sacrifice themselves by pumping nitrogen to the upper leaves to prevent a complete halt in photosynthesis. However, if nitrogen deficiency continues, even the upper leaves lose their green color and develop widespread yellowing.
In the case of magnesium deficiency, the porphyrin ring is also severely affected. Magnesium ions, which normally sit at the center of the ring, are missing. The chlorophyll molecules remain connected through nitrogen bonds, allowing electron transfer and energy transport to continue initially. However, over time, iron replaces magnesium as a temporary solution. With prolonged magnesium deficiency, the center of the ring completely breaks down, and the porphyrin ring structure is destroyed.
Because only the center of the ring is missing, magnesium deficiency manifests as a cloudy or spotted (mottled) yellowing pattern, which indicates severe magnesium shortage. If the deficiency persists, the leaf tissue becomes necrotic and eventually dies.
During nitrogen and magnesium deficiencies, it is recommended to use the emergency treatment suggested by Emami Corp:
- Greener + Violence + Root CMC
- Foliar spray at a ratio of 2 + 2 + 1 Kg per 1000 liters of water (0.2%)
- Apply in irrigation water at 20 kg per hectare
