Purple Corn Syndrome
Purple Corn Genetics
Impact on Crop
• Purple corn syndrome commonly shows up in corn fields
every year, typically following periods of low temperatures.
• Testing of corn plants that exhibit genetic purpling at the
seedling stage has shown no evidence of adverse effects on
metabolism, growth, or yield.
• Purple seedling color results from the expression of
anthocyanin pigment formation.
• Most corn hybrids contain five of the eight genes required to
produce the purple color.
• The other three genes are only present in certain hybrids,
and some of these genes are cold sensitive.
• Hybrids that develop the purple pigment when exposed to
cold temperatures have been found to contain as much
chlorophyll (the green pigment) as hybrids that remain green
when grown under the same cool conditions.
Purple corn as a result of genetic tendency for this trait. The hybrid
on the left out-yielded the hybrid on the right by 8 bu/acre.
This cross section of corn leaf tissue illustrates the
accumulation of anthocyanin pigments. Notice the purple
pigmentation is produced in the top layer of cells and does
not affect the chlorophyll content in the plant..
Phosphorus Deficiencies
• Phosphorus deficiency symptoms can be manifested as an
accumulation of purple pigments in leaves.
Cold Conditions Trigger Purple Corn
• Phosphorus level, as determined by soil tests and an
examination of the fertility programs used, may determine
whether phosphorus is likely deficient.
• Nighttime air temperatures in the 40’s, when day
temperatures are in the 60’s, are often adequate to trigger
purpling.
• These temperature sensitive genes are only expressed in the
seedlings prior to the 6-leaf stage of growth, which coincides
with the period most likely to have low temperatures.
• Corn normally outgrows the purpling condition by the time it is
12 inches tall. This can occur quickly if the weather warms up
and corn grows rapidly, or it can be slow if the weather
remains cool, retarding both root and shoot growth in the
seedling.
• Slower growth is caused by the cool temperatures, not the
purple pigment.
DuPont Pioneer Agronomy Sciences
®,
™,
SM
• If sufficient levels of phosphorus are already present, adding
extra phosphorus will not turn purple seedlings green.
Some genetics are more
prone to development of
purple color under cool
spring conditions. Plants
outgrow genetic purpling
with no adverse effect
on yield.
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Uneven Purpling
Corn seedling showing purple color due to phosphorus
deficiency. This likely resulted from phosphorus tie-up in
high pH soil as well as sugar beets as the previous crop.
• If purpling is not uniform it may indicate soil fertility problems
or inhibited root development.
• Since the inhibited root system may not take up enough
phosphorus for normal growth, plant sugars accumulate in
the plant and it "shows" the purple color.
• If plants are beyond the seedling stage (more than 6 to 8
leaves) and purpling is observed, then phosphorous
deficiency is likely.
• Phosphorus level, as determined by soil tests and an
examination of the fertility programs used, may determine
whether phosphorus is likely deficient.
• If sufficient levels of phosphorus are already present, adding
extra phosphorus will not turn purple seedlings green.
Root Development Inhibition Causes:
• Cool soil and night temperatures
Genetic Purpling vs Phosphorus
Deficiency
How can growers tell the difference between genetic
purpling and symptoms of phosphorus deficiency?
• First, examine the color of plants over the entire field. If the
purple color is uniform through the field, the cause is
probably genetic.
• If purpling is quite erratic, this may indicate that phosphorus
is limiting to plants in those areas.
• If plants are beyond the seedling stage (more than six to
eight leaves) and purpling is observed, then phosphorus
deficiency is likely.
• Soil conditions, either dry cool soils or wet poorly
drained soils
• Shallow planting
• Soil compaction
• Seed slot compaction or ‘smearing’
• Low phosphorus availability (especially on low or high
pH soils)
• Insect or nematode damage
• Seedling diseases
• Herbicide overlaps or over-applications
• Fertilizer injury
Purpling of early season corn.
Purple corn due to environmental conditions. Cold weather causes
the accumulation of anthocyanin pigment leading to purple color.
Authors: Nanticha Lutt and Mark Jeschke
The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture
and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual r esults may vary.