Reaction of kenaf and roselle grown in the burdekin river irrigation area to root-knot nematodes

Abstract

Experiments in pots and in the field showed that root-knot nematode (Meloidogyne javanica) could cause severe damage to kenaf (Hibiscus cannabinus) in the heavy, cracking, clay soils of the Burdekin River Irrigation Area in north Queensland. However, galls on field-grown plants were never observed more than 40 cm from the point of inoculation, suggesting that the texture of these soils limited the capacity of nematodes to spread laterally. Four lines of kenaf that were reputed to be resistant to root-knot nematodes and five lines of roselle (Hibiscus sabdariffa) with good growth characteristics were evaluated against Australian populations of M. javanica and M. incognita in both glasshouse and field experiments. All kenaf accessions were susceptible to root-knot nematodes in the glasshouse but three accessions showed significantly less galling than the standard kenaf cultivars in the field, suggesting that they had a limited degree of field resistance. In the glasshouse, all roselle lines were resistant to root-knot nematode and this resistance was maintained in the field. However, dry matter production from roselle was much less than that of kenaf in both root-knot nematode-free and rootknot nematode-infested sites.