Several selection procedures for obtaining alfalfa cultivars resistant to the stem nematode, Ditylenchus dipsaci, were carried out under field and greenhouse conditions. Field selection gave origin to the breeding line SIN UC F1 which showed significant increase in resistance in relation to its parent cultivars. The same germplasm was inoculated with 200 nematodes/plant. In one generation a 63% increase in resistance was obtained. Two cycles of recurrent selection in the greenhouse did not achieve yield increments in field evaluations.
