PEANUT GROWTH & DEVELOPMENT

IntroductionIntroductionArachis hypogaea L.

Fabaceae (Legume) family– is in the pea family, is not a nut

Native of South America– center of origin near Bolivia, Uruguay, and Paraguay

Four market types– Virginia (VA, NC, SC)– Runner (GA, AL, FL, MS)– Spanish (TX, OK)– Valencia (NM)

Two subspecies• hypogaea

– Do not flower on main stem

– Mature later

– Have higher water requirement

– Alternate branching pattern

– Larger seed

• fastigiata– Produce flowers on main stem

– Have sequential branching

– Mature earlier

– Lower water requirement

– Smaller seed

PEANUT MARKET TYPES

Runner (hypogaea subspecies)– grown primarily in Southeast

Virginia (hypogaea subspecies)– grown primarily in Virginia and North Carolina

Spanish (fastigiata subspecies)– grown primarily in Texas and Oklahoma

Valencia (fastigiata subspecies)– grown in primarily in New Mexico

Planted Acres of Selected U.S. Crops

Crops 2005 2006

Corn 81,759,000 78,561,000

Soybean 72,032,000 75,565,000

Wheat 57,229,000 57,344,000

Cotton 14,245,400 15,281,000

Sunflower 2,709,000 1,984,000

Peanut 1,657,000 1,242,000

Source: USDA – National Agricultural Statistics Service

Planted Acres2005 2006

Georgia 755,000 580,000

Texas 265,000 155,000

Alabama 225,000 160,000

Florida 160,000 130,000

North Carolina 97,000 85,000

South Carolina 63,000 60,000

Oklahoma 35,000 23,000

Virginia 23,000 17,000

New Mexico 19,000 16,000

Mississippi 15,000 16,000

USA total 1,657,000 1,242,000

PEANUT SEED

Made up of two

cotyledons & embryo

Embryo– plumule

– hypocotyl

– primary root

Planting Depth – 2.5”

1.5” of Moisture

Place Seed into Good Moisture

At germination and emergence, the hypocotyl and primary root are known collectively asthe radicle.

Peanut plants are in a vegetative growth stage forthe first 35 - 40 days after planting.

The peanut plant is very deep rooted.Roots can be found several feet deep.

Nitrogen fixing nodules on peanut root – This is NOT nematode damage!

A peanut leaf is made up of four leaflets.

Peanut plants will begin to “lap” about mid season providing complete canopy coverage

About 35 days after planting, the peanut plantbegins its reproductive stage with the onset ofblooms.

The peanut flower is a perfect flower, with bothmale and female parts present in the sameflower.

At the base of the peanut flower are theovaries.

Pollen grains shed inthe petals and attach tothe stigma. The firstpollen grains thatmature and travel downthe pollen tube, fertilize the ovaries.

a• The fertilized

ovary is referred to as a peg.

• The peg grows toward the soil surface and pushes 1 to 3 “ into the soil.

• The tip of the peg takes in water and nutrients, and swells to become the peanut pod.

Pegs entering the soil

Peanut blooms

Peanut pegs and pods below ground

Reproductive Growth Stages of PeanutGrowth stages of peanutK. J. Boote, Peanut Science 9:35-40

Beginning podBeginning peg

R2 R3R1

Beginning bloom

R4

R7

R5 R6

Beginning seed

Beginning maturity

Full pod Full seed

Heat or pests can damage pegs

The basal kernel developsfirst and faster than theapical kernel.

Basal kernel

Apical kernel

Cross section of peanut podat maturity. The embryo isvisible.

Affect of Seed Calcium on Percent Germination of Peanut Seed

40

50

60

70

80

90

100

100 200 300 400 500 600 700

Seed Ca, ppm

Ger

min

atio

n %

Source: D.L. Hartzog and J.F. Adams, Auburn University

Y = -43.6 + 0.668x – 8.06 x 10-4x2

Plateau = 95%R2 = 0.68

Irrigated Peanut Acres in Georgia*Irrigated Peanut Acres in Georgia*

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

1970 1975 1977 1980 1986 1989 1992 1995 1998 2000 2004

Irrigated Acres Planted Acres

*Based on survey by UGA Biological and Agricultural Engineering Department

7

17

51

56 54 54

53 58 58

36

56

Weekly Water Use by PeanutWeekly Water Use by Peanut

0.070.10.2

0.30.35

0.6

0.80.9

1.1

1.5

1.751.9

22.1

21.9

1.75

1.25

1

0.8

0

0.5

1

1.5

2

2.5

4 8 12 16 20

Weeks After Planting

Inches

Peak ET = .30 inches/day

Plant PeanutsMay 1

BloomInitiation

13 weeksJune - AugustTotal Water = 18.85

Irrigation Management

Critical water stage is 40 –110 DAP

DO NOT allow stress in last 30 days

Use scheduling system, i.e., Irrigator Pro

The seed is attached to the inner hull layer by the funiculus.The funiculus functions as an umbilical cord, transportingwater and nutrients to the kernel.

University of GeorgiaUniversity of Georgia

PEANUTPEANUT

Research and ExtensionResearch and Extension

PEANUTPEANUT

Maturity DeterminationAnd Harvest

Maturity DeterminationAnd Harvest

PEANUT HARVESTPEANUT HARVEST

The Good Ol’ Days???

Factors Affecting Peanut Maturity

Weather Too hot – hastens Too cool – slows Too cold – shuts down

Pest pressure Diseases – defoliation by leaf

spot, weakened vines, weak peg stems

Insects – defoliation by foliage feeders, chew peg stems

Fertility N def Mn def

Hull-Scrape Maturity Profile

Based on color change of mesocarp

Exocarp can be removed by knife or pod blaster

Color change goes from lighter (immature) to darker (mature): white, light yellow, dark yellow, orange, brown, black

Hull Scrape Maturity Profile

Peanut Wet Pod Blaster

Improper Digging Causes Yield Loss

Peanut Digger-Shaker-Inverter

Peanut Digger-Shaker-Inverter

Properly Dug and Inverted

Pods should be up off the ground

Allow about 3 days for windrow curing

DO NOT dig just ahead of rain event

Ideal conditions for curing include: low humidity, clear days, slight breezes

Combining“Pickin’ Peanuts”

Farmers Stock Peanut Transportation &

Handling

Post Harvest Practices to Reduce Risk of Aflatoxin in Farmer Stock

Peanuts

Level peanuts in trailer Dry to 10% moisture or less immediately following harvest

Follow proper curing and storage recommendationsMaintain safe moisture levels during and handling and storage