Several morphological and agronomic traits and the genetic diversity of nine Dactylis glomerata L. populations collected throughout Sicily (semi-arid Mediterranean environment) were evaluated for two successive years. Significant differences were recorded for morphological traits (plant height, leaf length, leaf width). In relation to the measurement of summer dormancy, the results suggest the expression of different levels of dormancy (completely dormant, semi-dormant, and non-dormant). For biomass yield, some Sicilian populations (SD63 and SD56) characterised by low levels of summer dormancy show production levels similar to the summer-active control varieties (Medly and Porto). However, SD46, with a much higher level of dormancy, gave biomass yield higher than the summer-dormant control variety (Kasbah). The genetic diversity evaluated by fAFLP analysis confirms the observed morphological and agronomic variability.