Instituto de Botánica del Nordeste (CONICET-UNNE, Fac. de Ciencias Agrarias) and Facultad de Ciencias Exactas y Naturales y Agrimensura,Universidad Nacional del Nordeste, Corrientes, Argentina. *Corresponding author: [email protected]; [email protected]

Arachis hypogaea (v.n. ‘‘peanut’’, ‘‘groundnut’’) is a cultigen that has become the third most important grain legume crop of the world (Duke 1981) because of its multiple use as human food, vegetable oil, feedstock and ground cover (Wynne and Halward 1989). This species is adapted to a wide ecological range of tropical and subtropical regions and is cultivated under diverse agricultural production systems in Asia, Africa and the Americas (Holbrook and Isleib 2001).