Efficient Evaluation of Resistance to Three Root-knot Nematode Species in Selected Sweetpotato Cultivars

Abstract

Five sweetpotato [ Ipomoea batatas (L.) Lam.] cultivars (`Beauregard', `Excel', `Jewel', `Hernandez', and `Porto Rico') were evaluated for resistance to three root-knot nematode species: Meloidogyne arenaria (Neal) Chitwood (race 2), M. incognita (Kofoid & White) Chitwood (race 3), and M. javanica (Treub) Chitwood. Resistance screening efficiency was assessed in both 400-cm 3 square pots and 150-cm 3 Conetainers™. Nematode infection was assessed as the percentage of root system galled, percentage of root system necrosis, and the number of nematode eggs produced per gram of root tissue. Means of these dependent variables were not different ( P ≤ 0.05) between container types, with Conetainers™ being more efficient to use. Root necrosis was not related to nematode infection, but was significant among cultivars ( P = 0.0005). The resistance responses of the cultivars differed depending on the nematode species. All five cultivars were resistant to M. arenaria race 2. `Hernandez', `Excel', and `Jewel' were also resistant to M. incognita race 3 and M. javanica .