Groundnut / Peanut (Arachis hypogaea) 

Importance of Groundnut

• Major oilseed crop of India and world.
• Known as “King of Oilseeds” due to high oil content.
• Provides edible oil, food, fodder, and industrial raw material.
• Groundnut cake is rich in nitrogen (7–8%) → excellent cattle feed.
• Improves soil fertility through biological nitrogen fixation.
• Important crop for rainfed farming systems.

Botanical & General Facts

• Botanical name: Arachis hypogaea
• Family: Fabaceae (Leguminosae)
• Chromosome number: 2n = 40
• Origin: South America (Brazil region)
• Pollination: Self-pollinated
• Crop type: Legume and oilseed

Meaning of Name

• Arachis → Legume
• hypogaea → Below ground
• Refers to underground pod development.

Morphology

• Root: Well-developed tap root with nodules. Fixes atmospheric nitrogen
• Stem: Herbaceous, branched, Growth habit varies with type
• Leaves: Tetrafoliate (four leaflets), Sensitive to light
• Flower: Yellow papilionaceous, 8–10 stamens forming monadelphous bundle
• Fruit (Pod): Develops underground, Contains 1–4 seeds

Unique Feature — Pegging Mechanism

• After fertilization, gynophore (peg) elongates downward.
• Pushes ovary into soil.
• Pod develops only underground.
• Horizontal positioning occurs inside soil.
• This is the most distinctive characteristic of groundnut.

Nutritional Quality

• Oil content: 44–50%
• Protein: ~25%
• Shelling percentage: ~70%
• Rich in B-group vitamins (except B12)
• Protein biological value comparable to casein

Types of Groundnut (Growth Habit)

• Bunch / Spanish type: Early maturity, Erect growth, No dormancy, Suitable for irrigated areas
• Spreading / Virginia type: Late maturity, Prostrate growth, Higher yield potential

Climate Requirement

• Tropical and subtropical crop
• Optimum temperature: 25–30°C
• Requires warm climate during growth
• Dry weather at maturity
• Sensitive to frost and waterlogging.

Soil Requirement

• Best soil: Sandy loam to loam
• Requires well-drained soil for peg penetration
• Ideal pH: 6.0–7.5
• Heavy clay soils reduce pod formation.

Cropping Seasons in India

• Kharif → Major season (rainfed)
• Rabi → Irrigated areas
• Summer → Limited regions

Physiological Features

• Short-day plant
• C3 plant
• Photosensitive leaves show nyctinasty (sleep movement)

Economic Uses

• Edible oil production
• Peanut butter
• Confectionery products
• Animal feed
• Soil improvement

Key Concept Insights

• Pegging requires loose soil → hence sandy soils preferred.
• Oil accumulation increases during pod filling stage.
• Rabi crop yields more due to less disease pressure.

High Yield Exam Facts

• Groundnut is a self-pollinated oilseed legume.
• Pods develop underground.
• Peg is called gynophore.
• Oil content about 45%.
• Bunch types have no dormancy.

Seed Rate, Spacing & Plant Population

Bunch / Erect type (Kharif)

• Seed rate: 100–120 kg/ha
• Plant population: 3.33 lakh/ha
• Spacing: 30 × 10 cm

Spreading type (Kharif)

• Seed rate: 80–100 kg/ha
• Plant population: 2.22 lakh/ha
• Spacing: 30 × 15 cm

Rabi bunch type

• Seed rate: 125–140 kg/ha (25% higher)
• Plant population: 4.44 lakh/ha
• Spacing: 22.5 × 10 cm or 30 × 7.5 cm
• Higher seed rate in rabi due to slow growth under cool conditions.

Land Preparation

• Requires fine, loose seedbed for peg penetration.
• 1 deep ploughing + 2–3 harrowings.
• Good leveling ensures uniform irrigation.

Nutrient Management

Typical recommendation:

• Nitrogen → 20 kg/ha
• Phosphorus → 40–60 kg P₂O₅/ha
• Potassium → 40 kg K₂O/ha
• Gypsum → 500 kg/ha at flowering (for calcium)
• Calcium is essential for pod development.

Irrigation Management

Critical stages

• Flowering → 35–40 DAS
• Pegging → 55 DAS
• Pod development → 65–70 DAS
• Avoid waterlogging to prevent pod rot.

Weed Management

Critical period → 15–45 DAS

Control methods: Hand weeding at 20–25 DAS, Pendimethalin pre-emergence

Varieties

Kharif Varieties

• Bunch / Spanish: Jyoti, Kadiri, Kisan, TMV-11, TMV-12
• Semi-spreading: TMV-10, Kadiri-2, Kadiri-3, BP-1, BP-2
• Spreading / Virginia runner: Type-28, Type-64, Chandra, M-13, Punjab-1, TMV-1, TMV-3

Rabi Varieties: ICGS-11, ICGS-44. Yield potential: 35–55 q/ha (highest)

Aflatoxin Problem

• Caused by fungus Aspergillus flavus.
• Occurs during storage under high moisture.
• Leads to serious health hazards.
• Prevent by proper drying and storage.

Harvesting & Post Harvest

• Harvest when leaves turn yellow and pods mature.
• Dry pods to 8–10% moisture.
• Proper curing improves quality.

Yield: Kharif → 15–20 q/ha, Rabi → Higher yield due to better management

Important Institutions & Missions

• Technology Mission on Oilseeds (1986) → Boost oilseed production
• TEMPO → Expanded mission including pulses
• SOPA → Soybean industry development
• ITC → Sunflower hybrid promotion
• MAHYCO → Hybrid seed development

High Yield Exam Facts

• Oil content → 44–50%
• Pegging is unique feature
• Critical stages → Flowering, Pegging, Pod development
• Bunch types → No dormancy
• Aflatoxin caused by Aspergillus flavus
• Highest yield varieties → ICGS-11, ICGS-44