Vine Cuttings Technique for Evaluating the Reaction of Dioscorea rotundata Varieties to Root-Knot Nematodes

Abstract

Root-knot nematodes (Meloidogyne spp.) contribute to low productivity and post harvest losses of white yam (Dioscorea rotundata). This study evaluated yam cultivars for resistance to Meloidogyne spp. using plants generated from single node vine cuttings. Forty accessions of D. rotundata were selected for the study and laid out in a randomized complete block design with 10 plants per replicate, three replicates and two treatments (Meloidogyne-inoculated and uninoculated). Vines were planted in vertically hanging bags and inoculated four weeks after with 500 eggs of Meloidogyne spp. Plants were harvested sixteen weeks after inoculation and data were collected on weight of tubers, nematode populations in tubers and soil, and nematode damage to tubers. Vine survival was up to 60%, although inoculated vines had lower rates of survival. All the surviving vines produced tubers of various sizes which differed between the control inoculated tubers. Based on galling index (damage) and reproductive factor, five accessions were designated as resistant with the remaining accessions being susceptible. The use of vine-cuttings was found to be effective for screening yam varieties for resistance to Meloidogyne spp.