Selection for resistance to the root-lesion nematode in alfalfa

A study was conducted to evaluate response of alfalfa (Medicago sativa L.) to selection for resistance to the root-lesion nematode (Pratylenchus penetrans (Cobb) Filipjev and Sch.-Stek.) under growth-room facilities. Six hundred plants of the cultivar Vernal were inoculated with root-lesion nematodes. Counts were made 13–14 wk later of the number of nematodes g −1 root. Selections were made for relatively low counts (resistant) and high counts (susceptible). Selections were self-pollinated, and the S 1 progeny of nine plants (five resistant and four susceptible) were evaluated. The S 1 progenies from both types of selections had similar counts. The S 2 progenies of resistant S 1 parents, however, had lower counts than those of susceptible parents. The F 1 crosses generally reacted as expected on the basis of the S 2 parents. Results of this study suggest that progress can be made in breeding for resistance to the root-lesion nematode in alfalfa.Key words: Nematode, Pratylenchus penetrans, alfalfa, selection