Host suitability and response of different vegetable genotypes to Meloidogyne incognita race 2 and Meloidogyne javanica in South Africa

Abstract

The host suitability of 20 locally available genotypes of Capsicum, 10 of Daucus carota, 7 of Beta vulgaris- and 3 of Spinacea oleracea were assessed in separate greenhouse studies for resistance to Meloidogyne incognita race 2 and M. javanica, respectively. Substantial variation existed amongst the vegetable genotypes in the greenhouse screenings with regard to their host status to the respective root-knot nematode species. None of the genotypes of D. carota, B. vulgaris and S. oleracea showed resistance to the nematode species tested. However, resistance to M. incognita race 2 was identified in Capsicum genotype “Tobasco”, which was subsequently verified in a follow-up microplot trial using a range of initial population densities together with a susceptible Capsicum genotype “Paprika”. Reproduction factors of the nematodes were used as the main criterion to evaluate resistance. In the microplot trial, genotype “Tobasco” showed resistance at the lower inoculum levels but not at the higher nematode population levels. The need exists for more frequent and extensive screenings of the various vegetable genotypes in order to provide small-scale farmers with better options for improved and sustainable yields.

Keywords:

• initial densities
• resistance
• root-knot nematode screening
• susceptibility
• vegetable genotypes

Acknowledgements

The authors are thankful to Charles Arries and Thuli Selabela form the Nematology Department of the ARC–ITSC for providing technical assistance.