Allelopathic potential of Avena sativa L. (oat) var. Argentina: bioassay-guided isolation of allelochemicals

The term allelopathy, first introduced by Molisch in 1937, refers to chemical interactions among plants, including those mediated by microorganisms [1]. Allelopathy may be further defined as an important mechanism of plant interference mediated by the addition of plant–produced secondary products to the rhizosphere [2]. During the last 30 years, the potential implications of allelopathy for agriculture, like insect, pest and weed management, have been described and discussed in detail [3]. Chemicals with allelopathic potential are present in nearly all plants and their respective tissues, including leaves, stems, roots, flowers, seeds, bark, and buds. These phytotoxins may be released into the environment in sufficient quantities to affect the growth of neighboring plants [4]. Nearly every class of secondary products or metabolites has been implicated in allelopathic interference [3]. In the literature is reported that oats are resistant to a number of important crop diseases and are grown in crop rotation to limit build up of pathogens [5]. In this work we investigated the allelopathic potential of Avena sativa L. (oat) var. Argentina by bioassay-guided isolation of allelochemicals, after field experiments. They indicated the allelophatic activity of this plant against several weed species. Aerial parts of oat were extracted and fractionated on the basis of phytotoxic activity on lettuce seeds. The active fraction was successively analyzed by LC-PDA-ESI-MS/MS analysis leading to identification of compounds with allelophatic propriety, corresponding to a flavonoid mixture of isoorientin 2-O-glucoside, vitexin 2”-O-arabinoside and isovitexin 2”-O-arabinoside.