Field Evaluation of Twelve Clones of Oregano Grown in the Main Production Areas of Argentina : Identification of Quantitative Trait with the Highest Discriminant Value

In Argentina, oregano (Origanum spp.) is one of the most important aromatic species. Leaves and flowering tops are used as seasoning, targeting the retail consumer, industrial and less to export. Local production has low-average yields due to the variability of cultivated material, the vegetative propagation methods used, and the lack of knowledge and adaptive experimentation on advanced cultivation practices. Clones of oregano grown in the country were collected in order to characterize the germplasm used in Argentina. Twelve oregano clones, sanitized by meristems culture and micropropagated in vitro, were field evaluated in three different growing locations. Regardless of growing site, the quantitative variables with more discriminating value were essential oils yield, internode length, length of the longest branch, fresh weight, dry weight of leaf and stem, leaf/stem ratio, and leaf area. Based on the quantitative traits, oregano clones can be classified into four groups. From the observations based on botanical characteristics, it was determined that the evaluated clones belong to three different taxa: Origanum vulgare ssp. vulgare, Origanum vulgare ssp. hirtum, and Origanum x majoricum (hybrid). Within each group, the clones belong to the same taxon.