Root-Knot Nematode Resistance in Pearl Millet From West and East Africa

Resistance to Meloidogyne incognita is important to provide stability to pearl millet production and to reduce nematode populations that can damage crops grown in rotation with pearl millet. The objectives of this study were to determine whether resistance to M. incognita exists in pearl millet from West and East Africa, and to determine if heterogeneity for resistance exists within selected cultivars. Resistance was assessed as nematode egg production per gram of root in greenhouse trials. Seventeen pearl millet cultivars of diverse origin were evaluated as bulk (S 0 ) populations. All African cultivars expressed some level of resistance. P3Kollo was among the least resistant of the African cultivars, Zongo and Gwagwa were intermediate, and SoSat-C88 was among the most resistant. Thirty selfed (S 1 ) progeny selections from SoSat-C88, Gwagwa, Zongo, and P3Kollo were evaluated for heterogeneity of resistance within cultivar. Reactions were verified in 13 S 2 progeny of each of the four cultivars. In S 1 evaluations, each of these cultivars was heterogeneous for resistance. Progeny reaction varied from highly resistant to highly susceptible. Patterns of apparent segregation of resistance varied among the four cultivars. Discreet resistant and susceptible phenotypes were identified in Zongo progeny, and it was estimated that two dominant genes for resistance segregated in this cultivar. Averaged across progenies, egg production on the four cultivars was less (P ≤ 0.001) than on the susceptible hybrid HGM-100, but was not different from resistant hybrid TifGrain 102. Reproduction of M. incognita on the S 2 progeny tended to confirm the results from inoculations of S 1 progeny. Heritability of nematode reproduction (standardized as the ratio of the value to HGM-100) determined by parent-offspring regression was 0.54. Realized heritability determined by divergent selection was 0.87.