Screening of okra (Abelmoschus species) genotype for resistance to root-knot nematodes (Meloidogyne species)

Okra has significant area under cultivation in Africa and Asia, despite it has been considered as a minor crop and not much attention has been given to okra improvement in international research program. Niger produced during 2008, 2794 t of okra in 5288 ha with mean productivity of 0.39 t.ha-1. This poor average productivity is far below than the mean productivity of East Africa (6.2 t.ha-1) and North (8.8 t.ha-1). Non-availability of varieties resistant to local biotic stresses is one of the major reasons for such a low productivity. Root-knot nematode disease is one of the constraints of commercial okra cultivation in region and cause of poor productivity. Durable host plant resistance/tolerance is considered as better option than the management tactic solely based on insecticide spray alone. The major objective of this study initited by AVRDC is to screening okra germplasm against root knot nematode in order to identify resistant lines. A total of 48 lines belonging to two species (A. esculentus and A. caillei) originated from different countries were screened following the protocol developed during this study. The results showed that after five weeks of inoculation, infestation of nematode is very fatal for susceptible okra genotypes. Cluster analysis using various parameters revealed that groups GI, GV and GII represented lines which are showing less gall index and poor reproduction rate of nematode, whereas GIII and GIV represented lines with more gall index with higher reproduction rate. The lines showing reaction towards resistance can be used in the breeding program.