Morphological adaptation of Lolium rigidum Gaudin to different conditions of the Mediterranean semi-arid environment.

A field evaluation, aimed at comparing several morphological traits of one cultivar ("Wimmera") and a Sardinian genotype ("Nurra") of annua l ryegrass, was carried out in Northern Sardinia. The two accessions were compared over two years in a field experiment, following the UPOV rules for the identification of new cultivars. The distinctness of "Nurra" for flag leaf, tiller, spike and spikelet length was clearly demonstrated. AIso, some "Nurra" plant adjustments in water-limited environmental conditions in late spring (elongation of spikelets and awns, late heading, increase of awn presence, higher fertility) seem to be an adaptive response of a drought-tolerant morphotype. The results of this experiment contribute to the agronomie valorisation of "Nurra" ryegrass as a valid drought-tolerant materia l suitable for introduction into the semi-arid pasture seed market.