The myrtle (Myrtus communis L.) case, from a wild shrub to a new fruit crop

Myrtle is an aromatic shrub spontaneously growing in the Mediterranean region. The edible fruits of this plant are widely used to produce a typical liqueur by hydroalcoholic infusion. The myrtle liqueur industry was completely based on the supply of the fruit harvest from wild plants with a consequent risk of selective pressure on the spontaneous species, low quality standardization and difficulties to assure every year an increasing quantity of raw material. In order to avoid the erosion of natural genetic resources a domestication process of the species was carried out starting in 1995. A mass selection of about 130 mother plants was the first step of a research completely performed on the Sardinia island, where the myrtle is a part of the Mediterranean maquis. Accessions were described for the main plant characters and morphology following a special descriptor list and only the pure clonal lines obtained by agamic propagation (softwood cuttings) were planted in a repository located in the experimental farm of the University of Sassari in Oristano (Central Western Sardinia). Yield quantity, plant vigor, rooting ability and resistance to nursery management were the main characters evaluated in the first stage of selection. The field observation of candidate selections produced a list of about 40 cultivars completely described and newly tested for fruit production and quality in different localities. Cultivars were compared also for fruit chemical composition and quality of the corresponding liqueurs, as well as for tolerance to the main transplant pathogens and phytoplasms. In vitro propagation of the better cultivars was the strategy adopted to provide nurseries of a great number of plants of few cultivars in the space of 4-5 years. The result was the plantation of about 200 ha that today may mitigate the effects of the harvest of wild fruits with a better quality standardization and yield security, with respect to seasonal meteoric events.