Purplish Corn Seedlings
Key Points
• Environmental and agronomic stress
can cause purplish corn seedlings.
• Stress related corn purpling is
usually not long lasting.
Purple Plants
Environmental and agronomic stresses can cause corn seedlings to become purplish in color (Figure 1). The
cause of the purplish color is the result of an accumulation of anthocyanin pigment, which is a sugar-containing
molecule. The pigment is natural and can occur without stress as it is responsible for purple grapes, red cabbage,
blackberries, autumn leaves, and other reddish-purple fruits, vegetables, and plants. Genetically, individual corn
products may be more purplish in color because of higher anthocyanin pigment levels. In most instances, corn
purpling caused by a stress is not long lasting and does not result in the non-realization of genetic yield potential.
However, if the cause is severe compaction or another non-remediable cause, season-long problems may occur
that can result in the loss of economic yield.
• Compaction and root injury from
insects, herbicides, and diseases
can cause purpling.
Purpling Causes
Purple corn seedlings can result from a deficiency in
phosphorus (P). The coloration is the result of corn roots
being unable to grow into and absorb non-mobile P, a
• Soils with a pH below 5.5 or greater
condition often associated with cool temperatures. Usually,
than 7.3 may also cause seedlings
the return of warmer temperatures allows for ample root
to take on a purplish cast.
growth, P absorption, and the fading of the purple coloration
without a lasting effect. If soil P is deficient or root growth is
restricted by severe compaction, the roots may not be able to
obtain or reach the P, which may cause the plant to remain
purplish throughout the growing season. Season-long P unavailability can result in poor plant growth and reduced
production. Soils with a pH lower than 5.5 or higher than 7.3 may also cause seedlings to take on a purplish cast
because of P availability. At these pH extremes, P becomes increasingly unavailable.1
Figure 1. Purple plant caused by phosphorus
deficiency.
Injuries to the root system by insects, herbicides, or diseases can cause purpling. Depending on the injury severity, the roots may be able to overcome these injuries with
little, if any effect on grain production. Severe injury could result in prolonged P deficiency and water absorption.
Cold temperature stress slows the plant's overall respiration ability, which can reduce its ability to metabolize sugars created through the photosynthetic process. The
produced sugars remain in the leaves instead of being distributed throughout the plant and can cause purpling. The "stored" sugars can also stimulate the formation of
additional anthocyanin pigment.
Some anthocyanin genes are cold-induced.2 Therefore, cold temperatures can turn these genes on, resulting in the production of the purple pigment.
Sources
1 Busman, L., Lamb, J., Randall, G., Rehm, G., and Schmitt, M. 2009. The nature of phosphorus in soils. Nutrient Management. University of Minnesota. www.extension.umn.edu/agriculture.nutrient-management/phosphorus/the-nature-of-phosphorus/.
2 Christie, P.J., Alfenito, M.R., and Walbot, V. 1994. Impactof low – temperature stress on general phenylpropanoid and anthocyanin pathways: Enhancement of transcript abundance and anthocyanin pigmentation in maize seedlings. Planta. 194:541-549. Additional Sources: Elmore, R. and Abendroth, L. 2006. Why are corn seedlings turning purple? IC-496 (10). Integrated Crop Management. Iowa State University. www. Ipm.iastate.edu/ipm/icm/2006/5-8/purplecorn.html. Mallarino, A., Sawyer, J.E., Creswell,
J., and Tidman, M. 2000. Soil testing and available phosphorus. IC-484(22). Integrated Crop Management. Iowa State University. www. ipm.iastate.edu/ipm/icm/2000/9-18-2000/availablep.html. Nielsen, R.L. (Bob). 2012. Prevalent purple plants perennially
puzzle producers. Corny News Network Articles. Purdue University. www.agry.purdue.edu/ext/corn/news/timeless/PurpleCorn.html. Nafziger, E. 2013. Purple and yellow corn plants. The Bulletin. University of Illinois. http://bulletin.ipm.illinois.edu/?p=1191.
Web sources verified 5/20/15. For additional agronomic information, please contact your local seed representative. Individual results may vary, and performance may vary from location to location and from year to
year. This publication was developed in partnership with Technology, Development & Agronomy by Monsanto.
Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather
conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Channel ®
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