Purple Corn Syndrome - What's Causing This?
This spring, growers may have seen corn plants turn a dark reddish or purple color in their fields. Don’t be alarmed, this actually quite common during cold and/or wet springs. So, what causes this phenomenon?
Purple color in corn plants is caused by a pigment called anthocyanin. Anthocyanins absorb blue/green light and reflect red/purple light. Research demonstrates that anthocyanins are only produced on the leaf surface and does not affect the amount of chlorophyl in the plant. Therefore, yield is typically not affected.
There are typically two reasons we see purple colored corn, the first being genetic. There are eight genes required to produce the purple color, and most commercial corn grown in the US contains 5 of said genes. The other three genes, present in some hybrids, are cold induced genes that we see when air temperatures hover around 40-60 degrees.
The second reason corn turns purple during the spring and early summer is due to a phosphorous deficiency. Phosphorus deficiency first appears on the lowest leaf tips and progresses up the leaf margin, until nearly the entire leaf is purple in severe cases. Phosphorus uptake may be reduced by things like restricted root growth, compaction, planter issues, and herbicide injury. However, lack of P can usually be correlated to cool and wet soils. Phosphorous diffusion is limited in soils less than 60 degrees Fahrenheit, and even more so in wet soil conditions.
Corn plants that turn purple typically grow out of the coloration around the V6 growth stage, all they need is sunlight and heat to advance root growth. Research has shown little to no yield difference between purple and green corn seedlings. It’s important to remember that young corn plants are extremely resilient; they can easily overcome early season stress and continue to yield well at harvest.