Host-status of sweet potato cultivars to South Africa root-knot nematodes

Abstract

Globally, most of the crop-related developmental projects collapsed due to the existence of aggressive plant-parasitic nematodes. Intensive South African biofortification efforts using exotic and local sweet potato (Ipomoea batatas) cultivars have hardly considered the inclusion of nematode resistance in plant breeding, despite the withdrawal of most nematicides from agrochemical markets. The objective of this study was to screen 12 selected biofortification sweet potato cultivars for host-status to South Africa tropical root-knot (Meloidogyne species) nematodes. Three exotic orange-fleshed, three local orange-fleshed and six cream-fleshed cultivars were used in three separate experiments of M. javanica and races 2 and 4 of M. incognita. In each experiment, 6000 eggs and second-stage juveniles/plant were used for inoculation, with nematode assessment performed at 56 days after inoculation. All tested biofortification exotic (except for cv. ‘W-119’) and local cultivars were hosts to Meloidogyne species and races, whereas three non-biofortication local cultivars, namely, ‘Bosbok’, ‘Blesbok’ and ‘Mvuvhelo’ were non-hosts. In conclusion, the findings suggested the likelihood of the existence of non-host-status in certain exotic and local sweet potato cultivars for use in plant breeding programmes against South African Meloidogyne species and races.

Keywords

• biofortified sweet potato
• host-status
• nematode resistance
• reproductive potential
• resistant hosts