Introduction • Arachis 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 Source: USDA – National Agricultural Statistics Service
PEANUT SEED • Made up of two cotyledons & embryo • Embryo • plumule • hypocotyl • primary root
Place Seed into Good Moisture Planting Depth – 2.5” 1.5” of Moisture
At germination and emergence, the hypocotyl and primary root are known collectively as the radicle.
Peanut plants are in a vegetative growth stage for the 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!
Peanut plants will begin to “lap” about mid season providing complete canopy coverage
About 35 days after planting, the peanut plant begins its reproductive stage with the onset of blooms. The peanut flower is a perfect flower, with both male and female parts present in the same flower.
At the base of the peanut flower are the ovaries. Pollen grains shed in the petals and attach to the stigma. The first pollen grains that mature and travel down the 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.
Peanut blooms Peanut pegs and pods below ground
R1 R2 R3 Beginning bloom Beginning peg Beginning pod R4 R5 R6 Full pod Beginning seed Full seed R7 Reproductive Growth Stages of Peanut Growth stages of peanut K. J. Boote, Peanut Science 9:35-40 Beginning maturity
The basal kernel develops first and faster than the apical kernel. Basal kernel Apical kernel Cross section of peanut pod at maturity. The embryo is visible.
Affect of Seed Calcium on Percent Germination of Peanut Seed Y = -43.6 + 0.668x – 8.06 x 10-4x2 Plateau = 95% R2 = 0.68 Source: D.L. Hartzog and J.F. Adams, Auburn University
Irrigated Peanut Acres in Georgia* 56 54 54 56 53 58 58 51 36 17 7 *Based on survey by UGA Biological and Agricultural Engineering Department
Weekly Water Use by Peanut Peak ET = .30 inches/day Plant Peanuts May 1 Bloom Initiation 13 weeks June - August Total 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, transporting water and nutrients to the kernel.
University of Georgia PEANUT Research and Extension
PEANUT Maturity Determination And Harvest
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