Radiation‐Induced Resistance to Root‐Knot Nematodes in Korean Lespedeza1

Abstract

Eighty‐three cultivars and strains of annual lespedeza, Lespedeza stipulacea Maxim. and L. striata (Thunb.) H. & A., 77 of which were irradiated L. stipulacea strains, were evaluated for resistance to two of the most prevalent forms of root‐knot nematodes (Meloidogyne incognita “A” and M. incognita “B”).‘Climax,’ ‘Kobe,’ ‘Korean,’ ‘Summit,’ and strain 29a were scored as susceptible, and ‘Rowan’ was scored as moderately resistant to each of these two forms of root‐knot nematodes. Seventeen percent of the 77 irradiated strains originating from strain 29a were scored as highly resistant to M. incognita “A”, 12% were scored as highly resistant to M. incognita “B”, and 9% were scored as highly resistant to both of these forms of root‐knot nematodes. In this study, 57% of the irradiated L. stipulacea strains had a significantly higher level of resistance to M. incognita “A” and 65% had a significantly higher level of resistance to M. incognita “B” than the check strain 29a. Approximately5 0% of the irradiated strains also were scored as either equal or superior in resistance to both M. incognita “A” and M. incognita “B” in comparison with the moderately resistant cultivar Rowan. Thus, through the use of irradiation, a new source of L. stipulacea germ plasm with a high level of resistance to these two forms of root‐knot nematodes is now available for improvemenotf this species.