Abstract

The available International Centre for Potato (C.I.P.)-introduced sweetpotato varieties were field- grown and screened for their resistance to natural populations of root-knot nematodes in the National Root Crops Research Institute farm fields at Umudike. Results showed that Accession33 (Naspot 5); accession 36 (K134); accession 39 (Santo Amaro) and accession 5(CIP breeding line) were resistant while most of the other accessions were susceptible and a few, hypersusceptible. In addition, significant results were obtained for saleable tuber yield and the highest root yielder was found to be accession 50 (Cemsa, (476g)), followed by accession 4 (one of the CIP breeding lines). It was also observed that most of the orange fleshed accessions were susceptible while those that appeared resistant were poor root yielders. With the appearance of some sources of resistance in some accessions, it is expected that further breeding work will be carried on in order to develop more resistant sweetpotato varieties. Keywords: Sweetpotato, resistance, field screening, root-knot nematode, Meloidogyne sp.