The genus Arachis L. (Fabaceae) in Rio Grande do Sul state, southern Brazil

Abstract

Genus Arachis L., from SouthAmerica, has several of its species being exclusive to Brazil. Two of them, A .burkartii and A. villosa, are restricted to Rio Grandedo Sul state, in the southernmost region of the country. The peanut plant (A. hypogaea) is traditionally grown in the state.Considering its yield, the peanut crop is under-cultivated in Rio Grande do Sul, mainly due to the susceptibility of its cultivarsto many diseases and pests. The main limiting factor to peanut breeding is the species narrow genetic base. As characterizingthe diversity of wild Arachis species is essential to achieve proper peanut breeding, taxonomic classification plays a major rolein providing a basis for the subsequent processes. Two other exclusively Brazilian species, A. pintoi and A. repens, have beenincreasingly grown in the state for ornamental, foraging, and erosion-control purposes. We aimed to consolidate knowledge ontwo Arachis species native to Rio Grande do Sul as well as to update knowledge on the three species grown in the state. Thiswork is the result of several decades of research on Arachis species from Rio Grande do Sul, which was performed by conductingexpeditions to rescue wild and cultivated germplasm and by reviewing herborized specimens from national and internationalherbaria. We analyzed 153 exsiccates and reviewed the germplasm database of the Brazilian Agricultural Research Corporation,focusing on samples collected at Rio Grande do Sul. We provide a dichotomous key that allows for distinguishing between theArachis species occurring in Rio Grande do Sul.