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Ohio State University Extension

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Corn Growth and Development

Additional topics on corn growth and development:

Hybrid Selection 

Grain Quality 
Maturity Date of Planting
Days to Maturity Rating System Seeding Depth 
Growing Degree Day (GDD) Maturity Rating System Row Width
Yield Potential and Stability  Plant Populations and Seeding Rates
Stalk Quality and Lodging Making Replant Decisions
 Disease Resistance and Tolerance  

Introduction to Corn Growth and Development:

A key step in high yield corn production is monitoring fields and troubleshooting yield-limiting factors throughout the growing season. Corn growers who understand how the corn plant responds to various cultural practices and environmental conditions at different stages of development are able to use management practices more efficiently and, thus, obtain higher yields and profits. Knowledge of growth and development also helps in troubleshooting problems related to abnormal growth caused by pest problems or inappropriate cultural practices. A helpful resource with information for diagnosing problems related to pests and environmental stresses during the growing season is the Corn, Soybean, Wheat and Alfalfa Guide, Ohio State University Extension Bulletin 827. 

Table 4-3 describes two of the most widely used staging systems for corn development. Extension agronomists use the Leaf Collar Method throughout the United States; crop insurance adjusters, however, use the Horizontal Leaf Method to assess hail and other weather-related plant damage. Table 4-4 shows a timeline relating corn growth and development to normal heat unit (growing degree day) accumulation during the growing season. 

Table 4-3: Growth Staging Systems for Corn. 

 
 

Field Corn Developmental Stages, Based on the Leaf Collar Method:

Vegetative Stages

Reproductive stages

VE

Emergence

R1

Silking

V1

1-leaf collar

R2

Blister

V2

2-leaf collar

R3

Milk

V3

3-leaf collar

R4

Dough

V(n)

nth-node

R5

Dent

VT

Tasseling

R6

Physiological maturity

 

Leaf Collar Method 

Start with first oval-shaped leaf as V1. Field defined as being at a given stage when at least 50 percent of plants show collars. 

Horizontal Leaf Method 

Growth staging system used by hail adjusters for hail damage assessment (Table 4-5).

  1. Identify uppermost leaf that is 40 to 50 percent exposed and whose tip is below the horizontal. 
  2. Typically, a horizontal leaf growth stage will be one to two leaf stages greater than the collar method. 

Table 4-4: A Timeline for Corn Growth and Development. 

 

Growth Stage*

 

Approx. GDDs

 

Cum. GDDs**

 

Comments

-

Planting

0

0

Seed planted

VE

Emergence

100

100

Coleoptile emerges through soil surface; seminal roots established.

V3

3-leaf collar

246

346

Growing point below soil surface; nodal roots forming.

V6

6-leaf collar

246

592

Growing point at or above soil surface; primary ear shoot initiated; nodal roots dominant now; tassel initiated; # of kernel rows around ear determined V6-8.

V9

9-leaf collar

246

838

Rapid growth underway; brace roots may be present at soil surface.

V12

12-leaf collar

182

1020

Lower 3-4 leaves may not be present due to stalk expansion and subsequent decomposition.

V15

15-leaf collar

150

1170

Kernel # per row determined.

V18

18-leaf collar

150

1320

Silk elongation is most progressed on uppermost ear.

V19

19-leaf collar

50

1370

Tassel near full size.

VT

Tasseling

50

1420

Last tassel branch visible; pollen may be shed on main branch of tassel before all branches of the tassel are fully extended.

 

R1

 

Silking

 

-

 

1420

One or more silks extending outside husk leaves; silks may be visible before tasselcompletely extended. A single plant can release ½ million or more pollen grains per day; silks receptive to pollen for about 10 days.

R2

Blister

266

1686

Occurs 10-14 days after R1; stress conditions, including drought can cause kernels to abort at R2-3.

R3

Milk

81

1767

Occurs 18-22 days after R1; “roasting ear” stage; kernel color changes from white/ clear to orange/yellow.

R4

Dough

214

1981

Occurs 24-28 days after R1; less risk of kernel abortion from stress.

R5

Dent

343

2324

Occurs 35-42 days after R1; stress can reduce kernel weight but not kernel # per ear.

R5

Dent –1/2 milk line

 

 

Occurs about 10 days after R5; 90% of total kernel dry matter accumulated.

 

R6

 

“Black Layer”

 

327

 

2650

Occurs 55-65 days after R1; physiological maturity—kernels have achieved their maximum dry weight and are safe from frost; kernel moisture averages 30% but can range from 25-40% grain moisture.

*Based on leaf collar method as defined by Abendroth, et al. (2011), Corn Growth and Development, PMR 1009 Iowa State Univ. Extension, Ames, IA. 

**Approximate growing degree days (GDDs) between growth stages and cumulative GDDs since planting according to Nielsen, RL. 2011. Predicting Corn Grain Maturity Dates for Delayed Plantings. Corny News Network, Purdue Extension. [online] kingcorn.org/news/timeless/RStagePrediction. html and Nielsen, R.L. 2016. Grain Fill Stages in Corn. Corny News Network, Purdue Extension. [online] kingcorn.org/news/timeless/GrainFill.html. 

Table 4-5 lists estimated yield loss resulting from varying amounts of leaf area destruction for several stages of development. Although this table was developed to determine yield losses resulting from hail damage, it can also be used to help assess losses resulting from other defoliation injuries (such as wind, frost, insect feeding, herbicide damage, and foliar nitrogen “burn”). The most common damage from hail is loss of leaf area, although stalk breakage and bruising of the stalk and ear may also be severe. Note that the largest yield losses result from defoliation damage that occurs during the late vegetative stages and the reproductive stages (silking and tasseling). Defoliation at early growth stages does not affect yield the same way as it does at later growth stages because much of the plant’s total leaf area is not yet exposed. Extensive defoliation of plants in the 10-leaf growth stage (or V8, eight-leaf collar stage) does not result in a large yield loss because only 25 percent of the leaf area is exposed and the plant can easily recover from early damage. On the other hand, severe damage to plants during tasseling results in a large yield loss because, by that time, 100 percent of the leaf area has been exposed and cannot be replaced. 

Table 4-5: Effect of Corn Leaf Area Loss at Various Growth Stages on Corn Yield*. 

Percent Leaf Area Destroyed

Growth stage**

10

20

40

60

80

100

Percent Yield Loss

7 leaf (V5)

0

0

0

4

6

9

10 leaf (V8)

0

0

4

8

11

16

13 leaf (V11)

0

1

6

13

22

34

16 leaf (V14)

1

3

11

23

40

61

Tasseled (VT/R1)

3

7

21

42

68

100

Late milk (R2)

1

3

10

21

35

50

Dent (R4)

0

0

3

10

17

24

*Adapted from Corn Loss Instructions, NCIS publication No. 6102, Rev. 2013 

**Based on horizontal leaf method for staging plant growth (V/R-stage is shown in parentheses – the horizontal leaf stage is approximately two- leaf stages greater than leaf collar method). 

Early killing frost in the fall may damage immature corn and reduce yield. The effect of frost damage to corn depends on the severity of defoliation, stalk damage, and stage of growth (see Chapter 1, Figure 1-4, for the median fall frost dates). Tables 4-6 and 4-7 provide yield loss and moisture estimates resulting from premature plant death (defoliation) during grainfill. 

Table 4-6: Yield Loss in Corn as a Result of Plant Defoliation at Three Kernel Development Stages. 

 

Kernel Development Stage

 

Percent Grain Yield Reduction

Soft dough (R4)

34-36

Full dent (R5)

22-31

Late dent (late R5)

4-8

Source: Afuakwa, J.J., and R.K. Crookston. 1984. Using the kernel milkline to visually monitor grain maturity in maize. Crop Science 24: 687-691. 

Table 4-7: Whole Plant and Kernel Moisture of Corn at Four Kernel Development Stages.

 

Kernel Development Stage

Kernel

Whole Plant

Percent moisture

Soft dough

62

>75

Full dent

55

70

Late dent

40

61

Physiological maturity (black layer*)

32

53

*Black layer―indicates end of kernel growth and maximum kernel dry weight (physiological maturity).

Source: Afuakwa, J.J., and R.K. Crookston. 1984. Using the kernel milkline to visually monitor grain maturity in maize. Crop Science 24: 687-691.