Abstract

Meloidogyne incognita race 2 and Meloidogyne javanica are widely distributed in South Africa where they cause enormous crop yield losses. Host-status of commercial maize (Zea mays L.) genotypes to the two nematode species was investigated under greenhouse conditions. Thirty-two maize genotypes, for each nematode species were arranged in a randomised complete block design, with six replicates. The experiments were conducted in summer and repeated in autumn. Fifty-six days after inoculating each treatment with 10 000 juveniles, reproductive factors and penetration indices (PIs) were subjected to analysis of variance and means separation achieved using Duncan’s multiple-range test. Reproductive factors suggested that three open-pollinated varieties, namely: OBATAMPA, QPM-SR and QS-OBA were non-host to both M. incognita race 2 and M. javanica in all trials. Certain hybrids and OPVs were also non-hosts to the two nematode species, although the result was not consistent throughout all the trials. Penetration indices suggested that OBATAMPA had post-infectional non-host status, whereas QPM-SR and QS-OBA had pre-infectional non-host status. In conclusion, results of this study demonstrated that non-host status to M. incognita race 2 and M. javanica existed in certain maize genotypes that are commercially available in South Africa. Also, in some of the genotypes, the non-host status was introgressible.

Key words: Penetration index, pre-infectional resistance, post-infectional resistance, reproductive factors.