Expression of Resistance to Meloidogyne incognita in Kenaf Cultivars (Hibiscus cannibinus) under Field Conditions

Field studies were conducted in 2003 and 2004 to investigate the reaction of 10 varieties of kenaf to natural infestation of Meloidogyne incognita. Ten weeks after planting, ten randomly selected plants per variety were assessed for root galling. Plants were carefully uprooted soil adhering to roots was washed off under a gentle stream of tap water and roots then were observed using a stereo microscope. Eggs were extracted from the roots with sodium hypochlorite. The reproduction factor (Pf / Pi) was calculated. Data were collected on plant height, stem girth, days to maturity, number of seeds and seed yield and the final figures of these parameters were analyzed by of variance and mean separation by Duncan's Multiple Range Test. Gall index and nematode reproduction factor varied significantly among the kenaf varieties. AU 64 recorded the tallest height of 2.2 m followed by Ex-Funtua, Ifeken 100 and G 45 whereas the lowest height was recorded for Ifeken 400 and Cuba 108. Days to maturity ranged from 120 to 135 days. Based on gall index ratings, AU64, Ex-Shika, Ex-Giwa, G 45 and the local variety were susceptible to M. incognita. Tianung 1 and Cuba 108 were very susceptible, whereas Ifeken 100 and 400 were resistant. Based on reproduction factor, AU 64, Ex-Shika, Ex-Giwa, G 45, Ex-Funtua and the local variety supported greater nematode reproduction, were good host to root-knot nematode, Tianung 1 and Cuba 108 were very susceptible while Ifeken 100 and Ifeken 400 were poor host to M. incognita.