This document provides information about the growth stages of corn and how water needs vary throughout the growth cycle. It discusses the key growth stages from emergence to maturity, what is visually occurring at each stage, and the number of days after sowing (DAS). Various graphs and tables show how leaf area index, photosynthesis, yield components, and water use rates change during the growing season. Stress during different stages, such as tasseling, can significantly impact yield through effects on grain weight, number of grains per cob, and other factors. Overall water needs peak during tasseling and pollination but decline as the plant reaches full maturity.

1. Drip Irrigated CornDrip Irrigated Corn

2. R2R2 R3R3 R4R4 R5R5 R6R6
VEVE V1V1 V3V3 V7V7 V10V10 VTVT R1R1 R6R6
Corn – Growing CycleCorn – Growing Cycle

3. Corn – Crop Growth StagesCorn – Crop Growth Stages
StageStage DASDAS FeaturesFeatures
VEVE 55 TheThe coleoptile emerges from the soil surfacecoleoptile emerges from the soil surface
V1V1 99 The collar of the first leaf is visibleThe collar of the first leaf is visible
V2V2 1212 The collar of the second leaf is visibleThe collar of the second leaf is visible
VnVn The collar of leaf number 'n' is visible. 'n' = final leaf no. (16-23)The collar of leaf number 'n' is visible. 'n' = final leaf no. (16-23)
VTVT 5555 The last branch of the tassel is completely visibleThe last branch of the tassel is completely visible
R0R0 5757 Anthesis or male flowering. Pollen shed beginsAnthesis or male flowering. Pollen shed begins
R1R1 5959 Silks are visible.Silks are visible.
R2R2 7171 Blister stage. Kernels are filled with clear fluid.Blister stage. Kernels are filled with clear fluid.
R3R3 8080 Milk stage. kernels are filled with a white,milky fluidMilk stage. kernels are filled with a white,milky fluid
R4R4 9090 Dough stage. Kernels are filled with a white paste.Dough stage. Kernels are filled with a white paste.
R5R5 102102 Dent stage. The grains are dented.Dent stage. The grains are dented.
R6R6 112112 Physiological maturity. Grain moisture is usually about 35%.Physiological maturity. Grain moisture is usually about 35%.

4. ♦ ♦
))Boedhram et.al., 2001Boedhram et.al., 2001((
150150 170170 190190 210210 230230 250250 270270
V1V1 V5V5
V8V8 V12V12 R1R1 R3R3 R5R5 R7R7
00
11
22
33
44
55
Day of year & PhenologyDay of year & Phenology
LeafAreaIndexLeafAreaIndex
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Seasonal course of leaf area index for irrigated andSeasonal course of leaf area index for irrigated and
non-irrigated corn )N applied @ 135 kg/ha(non-irrigated corn )N applied @ 135 kg/ha(
IrrigatedIrrigated
Non-irrigatedNon-irrigated

5. (Source: Stewart et.al., 2003)(Source: Stewart et.al., 2003)
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■ RdRd
Rd x LfyRd x Lfy
P 3079P 3079
LfyLfy
YuYu 5YuYu 5
P 3861P 3861
TMF 94TMF 94
00 11 22 33 44 55
00
1010
2020
3030
4040CanopyPhotosynthesisCanopyPhotosynthesis
))g/mg/m22
/day/day((
Leaf Area IndexLeaf Area Index
Corn Canopy Photosynthate Production per dayCorn Canopy Photosynthate Production per day
as a function of Leaf area indexas a function of Leaf area index
Y = 47.42 – exp )– 0.8148xY = 47.42 – exp )– 0.8148x((

6. 00 2020 4040 6060 8080 100100 00 1010 2020 3030 4040
2525
3030
2020
1515
1010
55
00 00
1010
2020
3030
4040
5050
6060
%%Leaf area lossLeaf area loss Days of continuous stressDays of continuous stress
%%CornYieldReductionCornYieldReduction
Yield loss emergence to V8Yield loss emergence to V8 Yield loss V8 to TasselingYield loss V8 to Tasseling
Corn Yield Reduction due to )a( leaf area lossCorn Yield Reduction due to )a( leaf area loss
and )b( moisture stressand )b( moisture stress
))aa(( ))bb((

7. ))Source: Atteya, 2003Source: Atteya, 2003((
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00
5050
100100
150150
200200
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300300
00
55
1010
1515
2020
2525
3030
StomatalconductanceStomatalconductance
))mmol/mmmol/m22
/sec/sec((
PhotosyntheticratePhotosyntheticrate
))mmol/mmmol/m22
/sec/sec((TT11 TT22 TT33 TT44 TT11 TT22 TT33 TT44
TT11 == ControlControl
TT22 == Stress at vegetative stageStress at vegetative stage
TT33 == Stress at Tasseling stageStress at Tasseling stage
TT44 == Stress at Vegetative + Tasseling stageStress at Vegetative + Tasseling stage
Effect of moisture stress at various growth stages on stomatalEffect of moisture stress at various growth stages on stomatal
conductance and Photosynthetic rate of cornconductance and Photosynthetic rate of corn

8. Control
Stressed
Control
Stressed
0
5
10
15
20
25
30
100-GrainWeight)g(
Ve geta tive Ta sse ling
Stress Period
Control
Stressed
Control
Stressed
0
20
40
60
80
100
120
140
160
No.ofGrainsPer
Cob
Ve ge ta tive Ta sse ling
Stress Period
Effect of Moisture Stress at Vegetative & TasselEffect of Moisture Stress at Vegetative & Tassel
Emergence stages on Yield ComponentsEmergence stages on Yield Components
))Source: Atteya, 2003Source: Atteya, 2003((

9. 9
Growth stage Percent yield loss per day of stress
(min-ave-max)
%
Seedling to 4 leaf --------------------
4 leaf to 8 leaf --------------------
8 to 12 leaf --------------------
12 leaf to 16 leaf 2.1- 3 -3.7
16 leaf to tasseling 2.5- 3.2 -4.0
Pollination (R1) 3.0- 6.8 -8.0
Blister (R2) 3.0- 4.2 -6.0
Milk (R3) 3.0- 4.2 -5.8
Dough (R4 3.0- 4.0 -5.0
Dent (R5) 2.5- 3.0 -4.0
Maturity (R6) 0.0

10. Seasonal water use of corn. The red line
represents the reference ET (ETo) based on
environmental conditions. The blue line takes
into account the growth stage of the crop.

11. StageStage Emergence &Emergence &
EstablishmentEstablishment
VegetativeVegetative Tasseling &Tasseling &
PollinationPollination
KernelKernel
developmentdevelopment
FullFull
MaturityMaturity
KcKc 0.30.3 0.3-1.20.3-1.2 1.201.20 0.830.83 0.500.50
ETo (mETo (m33
/day/day(( 3.363.36 4-64-6 6.06.0 5.55.5 5.05.0
ETc (mETc (m33
/day/day(( 1.01.0 1.2-7.21.2-7.2 7.27.2 4.64.6 2.52.5