Transcript Corn Growth Stages

Corn Growth Stages
Chad Lee, Ph.D.
Grain Crops Extension Specialist
University of Kentucky
Grain Crops Extension,
University of Kentucky
All growth stages presented here are based on…
How a Corn Plant Develops, Special Report No. 48
Iowa State University Press
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Extension Distribution Center
119 Printing and Publications Building
Iowa State University
Ames, Iowa 50011-3171
Telephone: (515) 294-5247
Fax: (515) 294-2945
http://www.extension.iastate.edu/pubs/Order.html
The material in this presentation comes from Iowa
State Special Report No. 48. This is an excellent
resource for any producer or agronomist.
Grain Crops Extension,
University of Kentucky
http://maize.agron.iastate.edu/corngrows.html#stages
Grain Crops Extension,
University of Kentucky
Vegetative Stages
Reproductive Stages
VE emergence
R1 silking
V1 first leaf
R2 blister
V2 second leaf
R3 milk
V3 third leaf
R4 dough
V(n) nth leaf
R5 dent
VT tasseling
R6 physiological maturity
* When staging a field of corn, each specific V or R
stage is defined only when 50 percent or more of the
plants in the field are in or beyond that stage.
http://maize.agron.iastate.edu/corngrows.html
Grain Crops Extension,
University of Kentucky
Grain Crops Extension,
University of Kentucky
VE
Development of
Nodal Roots
How a Corn Plant Develops, Special Report No. 48, Iowa State University, 1998
Grain Crops Extension,
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V3
Grain Crops Extension,
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V3
Growing point
is below the
soil surface.
Frosts on the
surface will not
kill the plants.
Freezing soil
temps will kill
the plant.
Flooding can
kill plants.
Root hairs begin to
form on Nodal
Roots.
Seminal Root
growth has
basically stopped.
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V6
Tassel
development
has started.
Ear shoot
formation has
also started.
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V6:
Typically when lower leaves begin to tear off of stalk.
To be certain about V-stages beyond
V6:
Split the entire stalk (from the tip to the
roots) in half with a knife.
The first five nodes will be clustered
near the bottom of the stalk and the 6th
node will be very close to the soil line.
Count nodes above the 6th node to
determine how many nodes are present.
The total number of nodes equals the Vstage of the plant.
For example 7 nodes = V7 corn.
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V6
Ear shoot.
Growing point is
above the ground.
Nodal Root System
is the primary root
system for
nutrients and
water.
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V6
Premature Tassel
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V9
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V9
Growth rate rapidly increases. Greater demand for nutrients and water.
Ear shoot.
Ear shoot.
Growing point.
Ear shoot.
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V12
Both kernel size and kernel number are being determined.
Any limits on water or nutrients at this phase will drastically
impact yields.
Earlier maturing hybrids will pass through this phase faster
than later maturing hybrids.
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About 10-12
days from
silking.
V15
Entering the
most critical
stage for yield
determination.
The plant is
most sensitive
to water and/or
nutrient stress
at this stage.
Irrigation- the 4
weeks around
silking are the
most critical.
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V15
Ear shoots near the top of the plant are
starting to out-grow ear shoots lower on
the plant.
Lower part of plant
Upper part of plant
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V18
Grain Crops Extension,
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V18
Lower part of plant
Upper part of plant
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V18
Lower part of plant
Upper part of plant
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VT - Tassle
Occurs when
last branch of
tassel is visible
but before silks
emerge.
Most
susceptible to
hail damage at
this stage.
Complete leaf
loss at VT will
result in little to
no yield.
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VT
Grain Crops Extension,
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Pollen shed
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R1 - Silking
Silks starting to emerge.
N uptake is rapid.
P uptake is rapid.
K uptake is nearly complete.
Watch for corn borer feeding.
Moisture is needed for pollination.
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R1 - Silking
Cob material
Premature kernel
Two to three days are required for all silks on an ear to be pollinated.
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R2 - Blister
Ear size is nearly complete.
Fertilized silks are starting to dry
out.
An miniature corn plant has
started to develop within the
premature kernel.
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R3 - Milk
Kernels are becoming yellow on the outside.
Silks are dry.
Kernels are at 80% moisture.
Stress becomes less of a factor as kernels start to dry down.
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R4 - Dough
Fluid in the kernel is becoming a consistency similar to dough. (70% moisture)
Almost ½ of the dry weight has been accumulated.
Five embryonic leaves have formed in the kernel.
These will be the first five leaves of a new plant as it emerges next year.
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R5 - Dent
Most of the kernels have dented on the top.
Most kernels are about 55% moisture at the start of R5.
A starch layer has formed and begins to progress down the kernel.
A frost will stop dry matter accumulation and reduce yields.
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R6 – Physiological Maturity
Blacklayer
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R6 – Physiological Maturity
Kernel is about 30 – 35%
moisture.
Kernels need to be at 13 to
15 % moisture for safe
storage.
Grain Crops Extension,
University of Kentucky
Vegetative Stages
Reproductive Stages
VE emergence
R1 silking
V1 first leaf
R2 blister
V2 second leaf
R3 milk
V3 third leaf
R4 dough
V(n) nth leaf
R5 dent
VT tasseling
R6 physiological maturity
* When staging a field of corn, each specific V or R
stage is defined only when 50 percent or more of the
plants in the field are in or beyond that stage.
http://maize.agron.iastate.edu/corngrows.html
Grain Crops Extension,
University of Kentucky
Grain Crops Extension,
University of Kentucky