Selection of rosemary (Rosmarinus officinalis L.) cultivars to optimize biomass yield

Rosmarinus officinalis L. (Labiatae) is a typical shrub of the Mediterranean maquis. In spite of its multiple ornamental and aromatic uses, and the great interest in its cultivation, only a few cultivars or clones have been well characterized. Our breeding program has focused on optimizing biomass yield and improving the quality of cultivated rosemary. In a preliminary phase (1996-1997), 31 mother plants were identified and described in situ throughout Sardinia; spring-shoot samples were then evaluated in laboratory. In a second phase (1996-2000), cuttings of selected clones were planted in a repository at the Experimental Station of the University of Sassari, in central-western Sardinia. In this paper, morphological, biometric, qualitative and phenological characters of fifteen rosemary selections of the repository are reported. Selections tended to produce flowers, fruit and new shoots in various periods of the year. Selections showed a high variability for spring-shoot length, leaf length and width, essential oil content of leaves, and percentage of leaf weight in relation to total shoot fresh weight. Clones with higher leaf/wood ratio and higher essential oil content were considered more suitable for the optimization of biomass yield.