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Corn Growth Stages. Chad Lee, Ph.D. Grain Crops Extension Specialist University of Kentucky. All growth stages presented here are based on…. How a Corn Plant Develops, Special Report No. 48 Iowa State University Press $2.00 - PowerPoint PPT Presentation
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Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
Corn Growth StagesCorn Growth Stages
Chad Lee, Ph.D.Chad Lee, Ph.D.
Grain Crops Extension SpecialistGrain Crops Extension Specialist
University of KentuckyUniversity of Kentucky
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
How a Corn Plant Develops, Special Report No. 48How a Corn Plant Develops, Special Report No. 48Iowa State University PressIowa State University Press$2.00$2.00
Extension Distribution CenterExtension Distribution Center119 Printing and Publications Building119 Printing and Publications BuildingIowa State UniversityIowa State UniversityAmes, Iowa 50011-3171 Ames, Iowa 50011-3171
Telephone: (515) 294-5247Telephone: (515) 294-5247Fax: (515) 294-2945Fax: (515) 294-2945
http://www.extension.iastate.edu/pubs/Order.htmlhttp://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.
All growth stages presented here are based on…
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
http://maize.agron.iastate.edu/corngrows.html#stages
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
Vegetative StagesVegetative Stages Reproductive StagesReproductive Stages
VE emergenceVE emergence R1 silkingR1 silking
V1 first leafV1 first leaf R2 blisterR2 blister
V2 second leafV2 second leaf R3 milkR3 milk
V3 third leafV3 third leaf R4 doughR4 dough
V(n) nth leafV(n) nth leaf R5 dentR5 dent
VT tasselingVT tasseling R6 physiological maturityR6 physiological maturity
* When staging a field of corn, each specific V or R * When staging a field of corn, each specific V or R stage is defined only when 50 percent or more of the stage is defined only when 50 percent or more of the plants in the field are in or beyond that stage. plants in the field are in or beyond that stage.
http://maize.agron.iastate.edu/corngrows.html
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
VEVE
How a Corn Plant Develops, Special Report No. 48, Iowa State University, 1998
Development of Nodal Roots
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V3V3
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V3V3
Root hairs begin to form on Nodal Roots.
Seminal Root growth has basically stopped.
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.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V6V6
Tassel development has started.
Ear shoot formation has also started.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
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 V-stage of the plant.
For example 7 nodes = V7 corn.
V6:V6: Typically when lower leaves begin to tear off of stalk. Typically when lower leaves begin to tear off of stalk.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V6V6
Nodal Root System is the primary root system for nutrients and water.
Growing point is above the ground.
Ear shoot.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V6V6Premature Tassel
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V9V9
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V9V9Growth rate rapidly increases. Greater demand for nutrients and water.
Ear shoot.
Ear shoot.
Ear shoot.
Growing point.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V12V12
Both kernel size and kernel number are being determined.Both kernel size and kernel number are being determined.
Any limits on water or nutrients at this phase will drastically Any limits on water or nutrients at this phase will drastically impact yields.impact yields.
Earlier maturing hybrids will pass through this phase faster Earlier maturing hybrids will pass through this phase faster than later maturing hybrids.than later maturing hybrids.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V15V15About 10-12 days from silking. 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.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V15V15
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
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V18V18
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V18V18
Lower part of plant Upper part of plant
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
V18V18
Lower part of plant Upper part of plant
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
VT - TassleVT - 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.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
VTVT
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
Pollen shedPollen shed
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R1 - SilkingR1 - Silking
Silks starting to emerge.N uptake is rapid.N uptake is rapid.
P uptake is rapid.P uptake is rapid.
K uptake is nearly complete.K uptake is nearly complete.
Watch for corn borer feeding.Watch for corn borer feeding.
Moisture is needed for pollination.Moisture is needed for pollination.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R1 - SilkingR1 - Silking
Cob materialPremature kernel
Two to three days are required for all silks on an ear to be pollinated.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R2 - BlisterR2 - BlisterAn miniature corn plant has started to develop within the premature kernel.
Ear size is nearly complete.Fertilized silks are starting to dry out.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R3 - MilkR3 - MilkKernels are becoming yellow on the outside.Kernels are becoming yellow on the outside.Silks are dry. Silks are dry. Kernels are at 80% moisture.Kernels are at 80% moisture.Stress becomes less of a factor as kernels start to dry down.Stress becomes less of a factor as kernels start to dry down.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R4 - DoughR4 - DoughFluid in the kernel is becoming a consistency similar to dough. (70% moisture)Fluid in the kernel is becoming a consistency similar to dough. (70% moisture)Almost ½ of the dry weight has been accumulated.Almost ½ of the dry weight has been accumulated.Five embryonic leaves have formed in the kernel. Five embryonic leaves have formed in the kernel. These will be the first five leaves of a new plant as it emerges next year.These will be the first five leaves of a new plant as it emerges next year.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R5 - DentR5 - DentMost of the kernels have dented on the top. Most of the kernels have dented on the top. Most kernels are about 55% moisture at the start of R5.Most kernels are about 55% moisture at the start of R5.A starch layer has formed and begins to progress down the kernel.A starch layer has formed and begins to progress down the kernel.A frost will stop dry matter accumulation and reduce yields.A frost will stop dry matter accumulation and reduce yields.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R6 – Physiological MaturityR6 – Physiological Maturity
Blacklayer
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
R6 – Physiological MaturityR6 – Physiological Maturity
Kernel is about 30 – 35% Kernel is about 30 – 35% moisture.moisture.
Kernels need to be at 13 to Kernels need to be at 13 to 15 % moisture for safe 15 % moisture for safe storage.storage.
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky
Vegetative StagesVegetative Stages Reproductive StagesReproductive Stages
VE emergenceVE emergence R1 silkingR1 silking
V1 first leafV1 first leaf R2 blisterR2 blister
V2 second leafV2 second leaf R3 milkR3 milk
V3 third leafV3 third leaf R4 doughR4 dough
V(n) nth leafV(n) nth leaf R5 dentR5 dent
VT tasselingVT tasseling R6 physiological maturityR6 physiological maturity
* When staging a field of corn, each specific V or R * When staging a field of corn, each specific V or R stage is defined only when 50 percent or more of the stage is defined only when 50 percent or more of the plants in the field are in or beyond that stage. plants in the field are in or beyond that stage.
http://maize.agron.iastate.edu/corngrows.html
Grain Crops Extension, Grain Crops Extension, University of KentuckyUniversity of Kentucky