Peanut

Arachis hypogaea

1. Identification and origin

Arachis hypogaea L. is an annual legume of the Fabaceae family, known as the peanut. It is native to South America, where it was domesticated thousands of years ago. The species has a unique characteristic: after fertilisation, the gynophore elongates and buries the ovary in the soil, where the fruit develops underground.

2. Economic importance

The peanut is a crop of great global economic importance, used for direct consumption, the production of edible oil, peanut butter, flours and industrial products. The seeds are rich in high-quality proteins and lipids. The crop is relevant in tropical and subtropical regions, being widely cultivated in South America, Africa, India, China and southern Europe.

3. Botanical characterisation

Annual herbaceous plant, of low habit and creeping or semi-erect growth. The leaves are compound, with four opposite leaflets. The flowers are yellow and arise in the leaf axils. After fertilisation, the gynophore curves and buries the ovary in the soil, where the fruit (pod) forms, containing 1–4 seeds. Reproduction is by seed.

4. Soil and climate requirements

It prefers warm climates, with optimum temperatures between 25–30 °C. It needs good light and a long frost-free period. It requires light, sandy or sandy-loam soils, well drained and with a pH between 5.5–7.0. Compact soils hinder penetration of the gynophore and reduce productivity. Regular irrigation increases the number and size of the pods, but waterlogging should be avoided.

5. Main pests

• Noctuid caterpillars: Helicoverpa armigera and other species attack leaves and young pods.
• Thrips: Frankliniella schultzei and Thrips palmi cause silvering and reduction of the photosynthetic area.
• Mites (Tetranychidae): cause discolouration and loss of vigour.
• Nematodes: Meloidogyne arenaria and M. hapla cause root galls.
• Weevils and soil beetles: damage to roots and underground pods.

6. Main diseases

• Early leaf spot: Cercospora arachidicola causes circular leaf lesions.
• Late leaf spot: Cercosporidium personatum causes severe necrosis.
• Root rots: Rhizoctonia solani, Sclerotium rolfsii and Pythium spp.
• Powdery mildew: Erysiphe polygoni forms white mycelium on leaves.
• Aflatoxins: produced by Aspergillus flavus and A. parasiticus under conditions of high humidity, especially post-harvest.

7. General crop management

It includes the use of certified seeds, sowing in light and well-prepared soils, weed control, monitoring of pests and diseases, and crop rotation with cereals or other non-legumes. Regular irrigation, without waterlogging, improves productivity. Harvesting should be carried out when most of the pods show adequate maturity. Rapid and correct drying is essential to prevent contamination by aflatoxins.

Bibliographic references

• EPPO Global Database – Arachis hypogaea.
• CABI – Crop Factsheets – Arachis hypogaea.
• FAO – Technical documents on oilseed legumes.
• Sanders, T. H. et al. (1995). Peanut quality and handling. American Peanut Research and Education Society.
• Stalker, H. T., & Wilson, R. F. (2016). Peanut: Genetics, Processing and Utilization. AOCS Press.
• Kays, S. J. (2011). Cultivated Vegetables of the World. Wageningen Academic Publishers.